Repro 1 Flashcards
1
Q
What is a free martian
A
- Heifer calve born to male twin - MOST ARE INSTERILE
○ Shorter vagina (not conclusive as can be other reasons) - Male calf generally has normal fertility
2
Q
What is male and female external genitalia, gonads and internal accessory structures
A
MALE external - penis and scrotum Gonads - testis internal accessory - epididymis, vas deferens, accessory sex glands FEMALES external - clitoris, labia gonads - ovary internal - uterine tubes, uterus
3
Q
What are the two main ducts that are precursors for male and female reproductive tracts
A
Indifferent stage - gonad (what called when don’t know sex)
2 ducts
1. Mesonephric duct - wolffian ducts - blue line
- Remains in the male to form the epididymis, vas deferens (efferent ducts), seminal vesicles and ejaculatory ducts
2. Paramesonephric duct - mullerian duct - red line
- Remains in the female to form the vagina, uterus, fallopian tubes
4
Q
What occurs with the male embryology
A
Sex determining region from the Y chromosome leads to the TDF formation -> development of the testes
- Sertoli cells -> present in the testes secrete AMH (anti-mullerian hormone) resulting in the regression of the Mullerian ducts
- Leydig cells -> produce the hormones - testosterone resulting in the development of the mesonephric duct -> male duct system
5
Q
What occurs with female embryology
A
- No AMH therefore no testosterone therefore no development Mesonephric duct - wolffian ducts as need testosterone therefore regress
○ Sometimes there are remnants of these ducts - Nothing suppressing the formation of the Paramesonephric duct - mullerian ducts therefore growth here
6
Q
What leads to a male XX (genotypically female but phenotypically male) and what reproductive organs present
A
- Internal male organs
- Genitalia can be ambiguous
○ Sometimes have a large clitoris - CAUSE -> Although XX but have SRY gene -> sex-determining region on the X chromosome
○ Breeding soundness exam in mares, hard time falling pregnant, need to karyotype the horse
7
Q
Female XO and Male YO what results
A
Female XO - turners syndrome in male - No SRY gene so look like female - Not lethal Male YO - Lethal mutation
8
Q
Female - XXX what results in
A
- Not lethal mutation
- Often fertile so generally don’t know
- Generally taller
9
Q
Male -XXY what is it called, what results
A
Klinefelter’s syndrome
- Most are infertile
- Cat with tricoloured male most likely to have this syndrome
○ To get these tortishell generally need two X chromosomes
10
Q
what is Androgen Insensitivity Syndrome and the 3 types
A
XY so have testes, with androgens that cannot act
- Partial or complete inability of cells to respond to androgens.
○ Complete AIS: XY individual looks like a normal female
§ Infertile
○ Partial AIS: genitalia partially masculinized
○ Mild AIS: genitalia masculinized (only diagnosed in males)
§ Some feminie features
§ Infertile -> cannot produce sperm
11
Q
What is the cause of 1) phenotypical male, gonadal female 2) phenoypical female, gonadal male
A
1) Phenotypical male, gonadal female -> commonly: androgen/progesterone administration in gestation
2) Phenotypical female, gonadal male -> commonly: Persistent Muellerian Duct syndrome
12
Q
what makes a true hermaphrodites
A
- Tissue of both ovary and testes within the gonads
○ Histological diagnosis - Some animals are true hermaphrodites
13
Q
What are the characteristic of ovaries in terms of size, appearance and areas
A
- Relatively small, oval to round, firm organs
- Nodular in appearance due to protrusion of follicles and corpora lutea from the surface
○ expect for horse -> ovaries look like kidneys (inside out) - Attached border at hilum (medial), free border opposite this, a cranial or tubal pole and a caudal or uterine pole
14
Q
Where is are the ovaries located in the horse, dog, cat and the ruminants and pigs
A
Horse, dog, cat
- Located in sublumbar region caudal to the kidneys
Ruminants and pigs
- Located close or at the pelvic inlet having undergone caudal migration
○ Similar to descent of the male gonads
- Uterine horns generally adopt a coiled shape (ruminants) or convoluted (sow)
15
Q
What are the 4 main structures of the ovaries and describe the 1st two
A
1) surface epithelium - continuous with the ovarian mesentery
2) tunica albuginea - surrounds the cortex as a thin layer of dense connective tissues
3) cortex
4) medulla
16
Q
Describe the cortex of ovaries and the structures within
A
dense stromal tissue of plump fibroblast-like cells and connective tissue
a. Stromal tissue
b. Follicles - fluid filled spheres that contain oocytes, in various stages of development, produce oestrogen that causes signs of oestrus or heat, promote conditions favouring fertilization and support of the ovum and zygote
c. Corpora lutea - endocrine cells which produce progesterone to support pregnancy
d. Corpora albicans
e. Atretic follicles
17
Q
Describe the medulla of the ovaries and the structures within
A
loose connective tissue containing vessels and nerves
a. Hilus -> where vessels and nerves enter and where the ovary attaches to its mesentery (mesovarium)
b. Vessels and nerves
c. Mesovarium -> how ovary attaches to the mesentery
18
Q
What is the function of the uterine tube and the 4 components
A
- Collect and conduct the ova to the uterus and generally the site of fertilization of the oocyte
1) infundibulum
2) ostium - leads into ampulla
3) Ampulla - tube
4) isthmus
19
Q
Describe the function and structure of the infundibulum and isthmus of the oviduct
A
Infundibulum - catches the ovum and leads to the abdominal opening of the tube - ostium
- Free margin of is irregular and forms processes called fimbriae which extend towards the ovary
○ They become active and motile at ovulation and move close to the ovary and catch and sweep the ova
Isthmus - tube that follows on from the ampulla
- Ends at the uterotubal junction with the uterine opening that may be located on small papilla that projects into the uterine lumen
- Uterotubal junction -> where AI tries to place the sperm for horses
20
Q
What are the 3 parts of the uterus
A
1) horn -> 2 therefore bicornuate
2) body
3) cervix - internal uterine orifice, cervial canal, external uterine orifice
21
Q
Uterine horns where begin, located, shape, site of what and what structures does it contain
A
- 2 horns begin at the uterotubal junctions and converge caudally to meet the uterine body
- Located within the abdomen
- Length and shape varies between species
- Site of IMPLANTATION
- Luminal surface possess varying orders of folds (pigs) or rows of small mounds (caruncles - ruminants)
Caruncles look like tentacle suckers -> provide attachment for the foetal membranes and therefore are only really developed and visible after the animal has given birth before
22
Q
Uterine body what is it, where positioned, ligament above and site of what
A
- Simple, relatively short muscular tube in domestic animals
- Positioned between the two horns cranially and cervix caudally
○ Intracorneal ligament -> between the horns - Site of SEMEN DEPOSITIONS in dog, pig and horse
23
Q
Cervix what is it, comprised of, special structures, lumen called and what lead into
A
- Thick walled terminal portion of the uterus located between uterine body and vagina
- Wall comprises of smooth muscle and dense fibrous tissue
○ Acts as a sphincter or valve regulating access to the uterus from the vagina
○ Easily palpated in large domestic species - Interdigitating cervix in many species - NOT ALL (not horse)
○ Harder to get into the bovine vagina - Lumen called the cervical canal opening to the uterine body being the internal uterine orifice and to the vagina the external uterine orifice
- Most distal part projects into the vaginal lumen as vaginal portion of the cervix
24
Q
Vagina what is it, where located, site of what and the 3 structures/areas
A
- Cranial portion of copulating organ
- Midline pelvic floor ventral to rectum
- Site of SEMEN DEPOSITION in ruminants
1. vaginal fornix
2. hymen
3. external urethral orifice
25
what is the site of semen deposition in the different species
- Site of SEMEN DEPOSITIONS in dog, pig and horse
| - Site of SEMEN DEPOSITION in ruminants
26
Describe the 3 components of the vagina
1. vaginal fornix
- Cranial end of the vagina
- Annular recess around vaginal portion of cervix
2. hymen
- Caudal end of the vagina
- Tissue on the roof - present in some mares
- Poorly developed in domestic species
3. external urethral orifice
- Demarcates the border of the vestibule
27
Vestibule what is it, where does it extend, located and the 6 main structures/areas
- Short terminal portion of the tubular genitalia that is shared with the urinary system
- Extends from the vagina to the vulva
- Caudal to the ischiatic arch and inclines ventrally
1. urethral opening
2. major and minor vestibular glands
3. constrictor vesticuli muscles
4. erectile tissue (vesticular bulb)
5. clitoris
6. clitoral fossa
28
what are some structures at the urethral opening for different species and what major and minor vesitcu.ar glands function as and which animals present in
1. urethral opening
- Hummock (bitch) - mount of tissue
- Suburethral diverticulum (cow, sow)
○ Both make catheterisation difficult
○ Should place hand on if want to go to vagina
2. major and minor vestibular glands
- Produce mucus that provide lubrication for the tract in preparation for copulation and parturition
○ Mucus production is most pronounced during oestrus
- Major -> found in cow, cat and some sheep
Minor -> dog, pig, horse and some sheep
29
what are the contrictor vesticuli muscles, ereticle tissue and the clitoris within the vestibule
constrictor vestibuli muscles
- Homolog to bulbospongioosus m.
- Constricts around bulbus glandis (penis) of canine during copulation
4. erectile tissue (vesticular bulb)
- Cavernous tissue - monolog to penile bulb
- Wall that contains extensive venous plexuses
5. clitoris
- Homolog to penis
- Erectile tissue in mare and bitch
- Glands of the clitoris is at the caudal tip of the body and only exposed part of the organ
30
Vulva what is it and describe the 4 structures within
- Single layer of tissue External opening of the female reproductive tract
1. Labia - 2
○ External opening of the female reproductive tract
2. Commissures
○ Labia meet dorsally at the dorsal commissure and ventrally at the ventral commissure
§ Ventral generally rounded and raised above the surrounding skin
□ In the mare it is rounded and encloses with clitoris
3. Constrictor vulvae
○ Contains fat and muscle bundles which are similar to the constrictor vestibuli in vestibule
4. Skin/integument
○ Covered with sebaceous and sweat glands and generally covering of fine hair
31
What is the main ligament of the female reproductive tract and the 3 parts
Broad ligament composed of 3 parts
1. Mesovarium
2. Mesosalpinx
3. Mesometrium
32
Mesovarium location and the 2 ligaments within
- Most cranial part that supports the ovary
- Attaches at the hilus and brings in vessels and nerves
- Cranial free boarder is thickened to form suspensory ligament
- Another thickening called the proper ligament between the uterine pole of the ovary to the cranial tip of the ipsilateral uterine horn
33
Mesosalpinx function, what does it form, how and species differences
- Supports and encloses the uterine tube
- Forms the ovarian bursa
○ Medial wall mesovarium and lateral wall mesosalpinx
○ Too small for ovary in mare to complete enclosure in carnivores
§ Opening is ventral in pig and ruminants and medial in carnivores
34
Mesometrium what does it suspend, and what other ligamnet is formed
- Suspends the uterine horns, body and cervix and is continuous with the perimetrium of the uterus (outer serosal covering)
- Carries the vessels and nerves to the uterus
- Cranial free border on either side carriers the round ligament of the uterus through the inguinal canal into the vaginal process
○ May be seen in carnivores, horse and cow
35
What are the 3 main blood vessels of the female reproductive tract
1. Ovarian artery
2. Uterine artery
3. Vaginal artery
36
Ovarian artery where does that arise and run
- Arises from aorta and runs within the mesovarium to give rise to ovarian branch, uterine and uterine tube branch
37
Uterine artery where does it run and arise from in the different species, the function and what special feature in ruminants and pigs
- Runs within the mesometrium and gives rise to branches that run cranially and caudally
○ Internal iliac via umbilical artery -> ruminants and pigs
○ External iliac -> in the horse
○ Absent in carnivores
- When present provides major supply to the uterus
- In large ruminants and pig a palpable turbulence (fremitus) can be felt in these vessels during pregnancy
38
Vaginal artery where run and arise from in different species
- Most caudal of the main blood vessels and also gives rise to cranial and caudal branches
○ Internal pudendal -> horse and carnivore
○ Internal iliac -> ruminants and pigs
39
Veins of the female reproductive tract what is the main one and what occurs in pigs and ruminants
- Satellite to the arteries
- Largest is the ovarian vein
- Pigs and ruminants -> veins form plexiform structures that come into close contact with ovarian a. similar to testicular vessels in male
○ Involved in endocrine signalling to the ovary from uterus
40
What is the general steps in the reproductive cycle and what occurs if pregnant or if not pregnant
1) Follicles in ovary grow, rupture and cervix opens ready for copulation
- Tract prepares for transport of spermatozoa and fertilisation of the ova
2) Ovulation -> release of occyte around oestrus
3) Corpora lutea form from ruptured follicles
4) Uterine vasculature increases and uterine mucosa prepares to support conceptus
NO PREGNANCY
- Degeneration and a new set of follicles begin to mature, uterus returns to resting state
PREGNANCY
Corpus lutea in the ovary are retained and uterine changes (mucosal to vascular), formation of the placenta to nourish the conceptus
41
what are the 6 main components of the male reproductive tract and the structures within
1. Gonads (paired) - testes: production of spermatozoa and hormones
2. Gonadal ducts (paired) - epididymis & ductus deferens: transport, maturation & storage of spermatozoa
3. Urethra (single) - continuation of duct - shared with urinary system
4. Accessory glands (paired / lobed)
○ production of bulk of ejaculate (semen) and medium to assist transport, deposition and fertilisation
a. ampullae
b. vesicular glands
c. prostate gland
d. bulbourethral glands
5. Copulatory organ (single) - penis: facilitates deposition of semen into female tract
6. Ancillary components - skin derivatives
a. scrotum: accommodates testes
b. prepuce: accommodates penis
42
Testis what is it (shape and feel), location in different species and the main external features
- Firm round to oval organ
- Location and orientation
○ Most external due to thermoregulation
○ Between the thighs and vertical -> ruminants
○ Between the thighs and horizontal -> horse
○ Close to the anus and oblique -> pigs
External features
- Crania and caudal poles
- Epididymal (attached) border/mesorchium (bring blood vessel down)
- Free border
- Lateral and medial surfaces
43
Describe the 8 internal features of the testis
1. Tunica vaginalis (visceral) -> SEROSAL
2. Tunica albuginea -> dense irregular fibrous connective tissue, may contain smooth muscle and inelastic
○ Contains a vascular layer which carriers major branches of the testicular vessels
3. Testicular vessels -> visible beneath the testicular capsule
4. Septa and lobules -> septa arise from inner surface of capsule and converge towards the centre dividing the parenchyma into lobules
5. Seminiferous tubules - sperm producing tissue - MAIN PORTION
6. Interstitial endocrine cells -> within the lobules, produce androgens - testosterone
7. Mediastinum -> where the trabeculae converge, can be central, displaced, defined to one pole etc.
8. Retes testis -> within the mediastinum within a network of canals which connect to germinal or seminiferous tubules that form loops.
44
Why is temperature regulation needed in the testis and what are the 3 main ways it occurs
Significance - spermatogenesis and hormone production
Thermoregulation via
1. Scrotal skin and connective tissue - thin and exposed to allow free airflow, abundant sweat glands
2. Cremaster muscles - contract and relax -> alter position of the testis relative to the body influencing the skin exposure
3. Testicular blood vessels - counter-current exchange allows cooling of arterial blood prior to entering the testis
45
Cryptorchidism what is it and issue
undescended testis
| - Can't make viable sperm but can make testosterone
46
Epididymis how long, what are the 3 component and what occurs in each, how attached
- Can be about 7m in the dog and up to 80m in the horse
- Head, body and tail
○ Head first then into the body and then tail
§ Mature in the tail wait for ejaculation
§ Head is attached to the cranial pole of the testis and tail attached to the caudal pole
47
What are the 4 main attachments of the epididymis and where attach from and to
1. Proper ligament of the testis -> attaches the caudal pole of the testis to the tail of the epididymis
2. Ligament of the tail of the epididymis -> anchors the tail of the epididymis to the wall of the scrotum
- Attaches to the scrotum
3. Mesorchium and mesepididymis
○ Mesepididymis -> attaches the testis to the body of the epididymis
4. Testicular bursa
48
What lead into the duct of epididymis and what does it become
- Efferent ductules -> within the head of the epididymis
- Duct of the epididymis -> where the efferent ductules come together to a single duct in the head of the epididymis
○ Convoluted course through body and tail of epididymis until emerge from tail becoming the ductus deferens
49
Where does the ductus deferens run and name the 3 main structures
- From tail of the epididymis through the inguinal canal into abdominal cavity with testicular vessels, passes around the ureter and dorsal to the bladder to enter the genital fold, converge to pass through the prostate gland and open into the urethra at the seminal colliculus
1) ampulla
2) ejaculatory duct
3) mesoductus deferens
50
Describe the 3 main structures of the ductus deferens and what species are they present in
1. Ampulla -> distal expansion of the ductus deferens in the ruminant, horse and dog
○ Generally grossly visible due to mucosal/submucosal glands
2. Ejaculatory duct -> in ruminants and horses the duct of the vesicular gland and ductus deferens both open together before enter the urethra -> this shared terminal area is the ejaculatory area
○ In other species the ducts enter the urethra separately
3. Mesoductus deferens -> mesentery the anchors the ductus deferens to the abdominal wall and becomes attached to the mesorchium -> referred to as the mesofuniculus
51
What is the spermatic cord and the 4 main structures within and surrounding
1. Tunica vaginalis (visceral)
2. Vessels (pampiniform plexus) and nerves
○ Counter current heat exchange
3. Muscles - cremaster muscle -> move the speramtic cord up
4. Ducutus deferens
52
What does the scrotum contain within the two parts and what are the 2 main structures
- Contains testis, epididymis and spermatic cords in an extra-abdominal location
- pair of flash-like cavities with neck and base one either side of midline
○ Narrow neck (containing spermatic cord) and broad base (containing the testis and epididymis)
- Each cavity contains small amount of the fluid
Structures
1. Scrotal septum -> separates the cavities in the midline
2. Scrotal raphe -> outside demarcation of the scrotal septum (shallow trough)
53
What are the 5 layers of the scrotum and describe
1. Skin and tunica dartos
○ Thin skin has many sweat glands, hair covering
○ Underlying connective tissue, elastic fibres and smooth muscle
○ Dartos is continuous with the scrotal septum and accommodates the skin to the testicular surface when testis moves in position
2. External spermatic fascia and scrotal ligament
○ Fibrous connective tissue loosely attached to dartos overlying the scrotal septum
3. Cremaster muscle and creastic fascia
○ Layer of connective tissue
○ Muscle arises from internal abdominal oblique and descends within the neck of the scrotum
4. Internal speramtic fascia
○ Supports the tunica vaginalis
5. Tunica vaginalis (parietal)
- Houses everything from the abdomen
54
what are the 2 main sections of the penis where does each run and the structures within
1) pelvic urethra - from the neck of hte bladder to the ischiatic arch where enters penis
1. urethral crest and colliculus seminalis
2. urethralis muscle
3. erectile/cavernous tissue
4. accessory glands -> ampulla, vesticular glands, prostate, bulbourethral glands
2) Penile (spongiose) urethra - extends the length of the penis
1. corpus spongiosum
2. urethral process
55
What are the 4 accessory glands, location, function and what species important in
1) Ampulla - Ruminants, horses and dogs
- Around the terminal portion of each deferent duct
- Contribute fluid similar to seminal vesicles in the ram and bull
- Stallion secrete gel component to the ejaculate
2) Vesicular glands and ejaculatory ducts
- Vesicular in the horse, firm and lobulated in the boar and bull
- Glands are located within the genital fold lateral to the ductus deferens
- produce seminal fluid that is rich in fructose which serves as an energy source for spermatozoa-> very large in the pig
- NOT PRESENT IN CARNIVORES
3) Prostate - big deal in a dog
- body or compact part and disseminate part
- Produce colourless, slightly acid fluid with high concentration of proteolytic enzymes - zinc and copper
4) Bulbourethral glands - large in horses and ruminants (either side of the urethra)
- Produce sialoprotein -> mucinous gelatinous material
- Small in cats and absent in dogs
56
what is the general function of the accessory glands and what type of glands
- Function is to provide energy for the spermatozoa (fructose), lubrication (mucus) to the reproductive tracts and neutralisation of luminal contents (seminal plasma is initially acidic, neutralisation initiates motility) and a vehicle for spermatozoa
- Generally the glands are compound tubular on compound tubuloalveolar in structure
57
What are the 3 parts of the penis, what within in different species
1. Glans - end of the penis, only has bulbus glandis in the dog
○ Made up of the urethra and spongiosum in horse
○ Tunica albuginea continues to the end in pigs therefore corpus cavernosum continues till the tip when there is only 1. tunica albuginea 2. corpus spongiosum 3. urethra
2. Body - sigmoid flexure only found in ruminants
3. Crura (root)
a. Corpus cavernosum - surrounded by the tunica albuginea and therefore constricted, gets smaller as heads towards the glans of the penis until disappears at the glans in horse or near the tip in pigs
b. Corpus spongiosum - surrounds the urethra and not surrounded by tunica albuginea and therefore not constricted, becomes larger as head towards the glans of the penis, eventually comes back up and surrounds the corpus cavernosum and forms the glans in the horse
58
What are the 2 types of penis and what each contains, which species found in
1) The fibroelastic or fibrous type
□ Contains relatively little erectile tissue with bulk being fibrous and elastic connective tissue
□ Has a S shaped bend or sigmoid flexure
□ In ruminants and pigs
2) musculocavernous or muscular type
□ Contains relatively abundant erectile tissue, the tunica albuginea and septa being less substitutional then above and much smooth muscle present
□ Present in horse and carnivores
59
How large is the glans penis in different species and what is different about the pig and ox penis
- Glans penis is small in pig, ox, cat, large in horse and complex in dog
- Pig and ox have a spiralling twist at free extremity of the penis
60
What are the 3 main muscles of the penis, type of muscle and their function
1) Ischiocavernosus mm. - skeletal muscle surrounding crura of the penis
○ Pumps blood into the corpus cavernosum
○ Positions penis during intromission and coitus
2) Bulbosponsgiosus m - skeletal muscle enveloping corpus spongiosus at bub
○ Pulses during ejaculation to assist in expulsion of semen
3) Retractor penis mm. - smooth muscle that arises from the caudal vertebrae and converge to the anus and run midline along the aspect of the body of the penis
○ Function: retraction of the penis into prepuce following coitus
61
What are the 3 main arteries of the penis what supply and where arise
- Main arterial blood supply branches from the internal pudendal arteries
- Gives rise to 3 branches
1) Artery of the bulb which supplies the corpus spongiosum
2) The deep artery of the penis which supplies the corpus cavernosum
3) Dorsal artery of the penis which courses on the dorsal aspect of the penis of the glans
○ Anastomotic connections to the external pudendal artery in the horse and carnivores
62
What is the prepuce and what are the 6 structures
- Invagination of skin forming a sheath about the free part of the penis on the ventral aspect of the abdomen with opening caudal to the umbilicus
1) Orifice
2) internal & external laminae
3) cavity
4) frenulum
5) preputial muscles (cranial and caudal)
6) preputial diverticulum - only present in the pig
63
What are the internal and external laminae of the prepuce
○ External -> forms external surface and comprises of typical haired skin
○ Reflects at the preputial orifice to become the internal lamina
○ Internal -> lines the preputial cavity and reflects onto free part of the penis to continue as the skin of the penis
- Loosely bound to allow for movement of the penis
64
What is the function of the cranial and caudal preputial muscles and the preputial diverticulum
5) preputial muscles (cranial & caudal) - assist in positioning the prepuce
○ Cranial preputial muscle is the most developed
○ Both attach to the preputial orifice
6) preputial diverticulum -> only present in the pig
○ Small out-pocketing or diverticulum of the cranial roof of the preputial cavity that is incompletely divided
○ Foul smell can accumulate here -> smegma that comprises of desquamated epithelia and urine
65
What are the 4 main functions of the male reperoductive system
1. To produce spermatozoa carrying genetic material
○ Seminal plasma = semen
2. Place semen into female reproductive tract
3. Achieve EFFICIENCY in these process -> high fertility
4. Meet artificial insemination requirements
66
List 6 influences of male reproduction
1. Genetics -> characteristics relating to reproduction often highly heritable
2. Age -> puberty, sexual maturity, old age
3. Nutrition -> underfeeding, good feeding, overfeeding
4. Social interactions, rearing
5. Environmental factors -> pollutants, predators
6. Management -> time of joining, length of joining, handling at mating, male to female ratios, artificial insemination (sperm per dose, handling semen)
67
What is the sex center and what determined by
- The site of libido and sexual arousal
- Efficiency determined by:
○ Genetics
○ Learning
○ Testosterone
- Libido can be: absent-low-moderate-high
68
List 4 sexually stimulating things in the environment
1. Other mounting (sense of sight) -> sense arousal
2. Pheromones (sense of smell)
3. Bull touches/rubs/licks cow (sense of touch)
4. Cow stands still
69
What is libido, what does it lead to, how occur
- The desire to mate/severe
- Leads to courtship behaviour, followed by erection, mounting, intromission
- Male sexual behaviour patterns imprinted on the brain in foetal/neonatal life
- Testosterone in the adult evokes the imprinted pattern
- Testosterone threshold
- Stallion shows more courtship than the bull
70
List 5 factors that affect libido
1. Testosterone threshold
2. Previous experience, training
3. Management
4. Sexual stimulation/environment prior to mating
5. Pain often adversely affects ability/inclination to severe
71
List 6 things that affect reproductive efficency in general
1. Age
- Puberty - onset then increase in efficiency
- Sexual maturity - plateau
- Old age - decline in efficiency
2. Breed
- Genetic constitution has a strong influence on sexual behaviour and testicular size
3. Season
- Reproductive efficiency absent or reduced during the non-breeding season in horses, sheep, goats
4. Climate
- Especially un-adapted animals in tropical countries
5. Nutrition
- Poorly fed animals less efficient
- Increased dietary protein increases ram sperm production
- Obesity may inhibit libido and testicular function
6. Management
- Where and when males grouped with females
- Male: female ratios
- Dominant vs subordinate males
- Fighting between males
72
What are the 6 main hormones involved in reproduction
1. Follicle stimulating hormone (FSH)
2. Luteinising hormone (LH)
3. Thyroid stimulating hormone (TSH)
4. Growth hormone
5. Prolactin
6. Adrenocorticotropic hormone (ACTH)
73
What is important with pineal gland in terms of breeding and what producers
Pineal gland
- Receives input re-daylight - rhythms
- Important for seasonal breeders -> horse, rams, hamsters, goats
- Synthesise and secretion of melatonin is dramatically affected by light exposure to eyes
○ Increase to a peak at night time - darkness
Melatonin
- Melatonin is anti-gonadotrophic (except in short day breeders)
○ Gonads are activated during distinct breeding season -> longer days
74
Spermatogenesis what is it, how long does it take in a bull and what controls it
- Series of events manifested by morphological changes during development of spermatogonia into spermatozoa
- This process takes 50d in bull
Control of spermatogenesis
- FSH acts to stimulate the Sertoli cells (fSh)
- LH acts on the Leydig/interstitial cells > testosterone
- Testosterone -> initiates spermatogenesis in conjunction with FSH, aids in the maintaining Spermatogenesis, sperm transport and mating behaviour
- Spermatogenesis continue with a mix of FSH, LH, Testosterone and Oestrogen with Inhibin (Sertoli cells)
75
What are the 3 phases of spermatogenesis
1) Spermatocytogenesis -> spermatogonia give rise to spermatocytes
2) Meiosis -> spermatocytes give rise to spermatids
3) Spermiogenesis -> spermatids transform into spermatozoa
76
What are the 6 steps in spermatogenesis
1) Proliferation of the gonocytes which are descendants of the primordial germ cells
2) Division of spermatogonia that line the seminiferous tubule near the basement membrane
3) Mitotic divisions of spermatogonia with the resulting cells either stay in the "resting pool" while the others proliferate several times undergoing stages 1 to 5 of division and differentiation
4) After the final division the resulting cells are called primary spermatocyte
END OF SPERMATOCYTOGENESIS
5) Primary spermatocytes then undergo the first two division that constitute meiosis
○ The first meiotic division produce two secondary spermatocytes
6) Division of the secondary spermatocytes complete meiosis and produces the spermatids
77
sertoli cells where found, what is their main function
- Found within the seminiferous tubules
- Have tight junctions that open at specfic times and allow the progression of spermatocytes to the abluminal compartment where meiosis occurs creating a spermatid
○ Important in spermiogenesis
- At certain times the cytoplasm of the spermatid is actively pinched off by the Sertoli cells and the spermatozoa are shed into the lumen of the tubules
Functions:
- Nurse cells for spermatids
- Spermination of the spermatid
- Separation of the circulatory system from the luminal environment of the tubules (blood-testis barrier)
78
How long does it take to reach puberty in bulls, rams, stallions and dogs/tomcats, and what is necessary
○ 10-12 months bulls
○ 4-6months rams
○ 13-18 months stallion
○ Dogs and Tomcats > 6months
- LH necessary for the development of the Leydig cells responsible for pubertal onset
- Adverse environmental factors (growth rate) delay puberty
- Genetic factors are important
79
What are the important reproductive hormones in the female and where do they come from
1. Hypothalamus: GnRH - act on anterior lobe
2. Pituitary:
○ anterior lobe: LH, FSH, Prolactin
○ posterior lobe: Oxytocin
3. Ovary: Oestrogen, Progesterone, Inhibin, Oxytocin, Relaxin, some Testosterone
4. Uterus: Prostaglandin F2α
5. Placenta: Progestogens, Oestrogens, (equine and human chorionic Gonadotropins only in horses and women, respectively)
80
What are 5 main functions of reproductive hormones
- Release of other hormones
- Stimulation of the ovary (gonadotropins)
- Sexual promoters (steroids)
- Pregnancy maintenance
- Luteolysis (destruction of the CL - corpus leteum)
81
Hypothalamus what sex is it inherently and what occurs in males and females
- Inherently female
○ GnRH surge centre in the male is "eliminated by testosterone that is converted into oestradiol.
○ female foetal ovaries produce oestradiol but still has tonic and surge centre due to:
§ female oestradiol is not able to cross the blood-brain-barrier because it is bound by alphafetoprotein and therefore cannot affect the hypothalamus.
§ In the male, the testosterone is crossing the blood-brain barrier without any problem and is then converted to oestradiol in the brain, so it is not affected by the alphafetoprotein.
82
What occurs before puberty in males and females in terms of hypothalamus and GnRH
- GnRH neurons in the regions of the tonic centre and in the surge centre of the hypothalamus release low amplitude and low frequency pulses of GnRH
○ Not enough oestradiol is produced to create positive feedback on surge centre so just negative feedback on the tonic centre occurs
83
What occurs after puberty in females in terms of hypothalamus and GnRH
- Tonic centre controls basal levels of GnRH and surge centre controls preovulatory GnRH surge
○ Negative feedback isn't as strong on tonic centre which leads to increase GnRH release and more FSH/LH release -> higher levels of oestradiol concentrations
§ Once oestradiol concentrations reach threshold level there is positive feedback on surge centre -> LH surge and ovulation
□ Once start cycling continue regularly for the rest of the life
84
What occurs after puberty in males in terms of the hypothalamus and GnRH release
- No surge centre so just simple negative feedback loop
○ Testosterone -> aromatized to oestradiol
§ oestradiol and remainder of testosterone have negative feedback on GnRH neurons
□ Neurons become less sensitive while puberty approaches
® More GnRH neurons can fire so more LH/FSH are produced
85
What makes up the hypothalamus and how does it communicate with the pituitary system and release hormones
- consists of nerve cell bodies that form the surge center, the tonic center and the paraventricular nucleus (PVN).
○ neurons of the surge and tonic centers produce Gonadotropin releasing hormone (GnRH)
○ Neurons of the PVN produce oxytocin.
- The hypothalamohypophyseal portal system facilitates communication between the hypothalamus and the pituitary.
○ This allows very small quantities of releasing hormone to be deposited into the anterior lobe (AL) of the pituitary, where other hormones are then released as a result, e.g. LH and FSH.
- The posterior lobe (PL) is not connected via the portal system and the hormones (such as oxytocin) are deposited directly through capillaries.
○ GnRH and Oxytocin are so called “neurohormones”.
86
What occurs with GnRH implants
first they lead to display of oestrus (release of LH and FSH, so called “flare effect”) but overtime downregulation (internalization of receptors) occurs and FSH and LH release decreases
○ Cyclicity ceases or, in cases of males, sperm production ceases
§ These effects are generally reversible
87
What are the 6 hormones produced by the ovaries and function of one
1) Oestrogens - oestradiol (main oestrogen)
2) Progestogens - Progesterone (main one)
3) Inhibin - made by growing follicle to inhibit the other via inhibit FSH release
○ Cattle, horses - one dominant follicle generally
○ Others -> if have one dominant follicle won't produce enough inhibin to stop the development of others - species that have litters
4) Oxytocin
5) Relaxin
6) Some testosterone
88
What are the 2 major phases in oestrous
1) Follicular phase: from regression of corpora lutea to ovulation (20% - cattle, Horses - 1 week)
○ Lots of follicles
1. proestrus 2. oestrus
2) Luteal phase: from ovulation until corpora lutea regression (80% - cattle, Horses - 2 weeks)
○ Very yellowing
1. meoestrus 2. dioestrus
89
What is the difference between oestrous and oestrus
- oestrous refers to the adjective (e.g. oestrous cycle) and oestrus refers to the noun.
- The term oestrus is commonly referred to as heat.
90
Follicular phase what are the 2 phases within, what occurs and how
1) Proestrus: formation of ovulatory follicles and increasing Oestradiol (E2) secretion
○ Begins when progesterone (P4) declines as a result of luteolysis and terminates at beginning of oestrus.
○ Transition from progesterone dominance to oestrogen dominance.
○ Follicle are recruited
○ Oestrogen also increases the receptors on the follicles to FSH in preparation for the increase in levels
2) Oestrus: sexual receptivity and peak E2 oestradiol secretion (except in the dog….)
○ Characterized by gradual progression to sexual receptivity in response to rising oestrogen levels
End of the phase you get ovulation
91
what are the 4 general events of the follicular phase and what are the 3 things that need to occur for ovulation
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General Four events
1. Gonadotropin release from AL of pituitary
2. Follicular preparation of ovulation
3. Sexual receptivity
4. Ovulation
What needs to occur for ovulation
- Not just surge of oestrogen
- PGE2 -> increase blood flow to ovary and dominant follicle -> hyperaemia -> oedema -> elevated hydrostatic pressure
- Other angiogenic factors as well
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92
Luteal phase what are the 2 phases and what occurs
1) Metoestrus: CL formation and rising progesterone levels - GENERALLY DON'T USE JUST USE DIOESTRUS
○ Period between ovulation and formation of corpora lutea.
○ Cellular and structural remodelling of ovulated follicle is called luteinisation.
2) Dioestrus: longest stage of the cycle; sustained progesterone secretion; ends with luteolysis (destruction of corpus luteum)
○ If recognises that pregnant will not undergo luteolysis
93
What are the 3 general phases of luteal phase and what effects does progesterone have
3 general phases in luteal phase
1) Corpora lutea formation
2) Production of progesterone
Luteolysis
Effects of progesterone
1) Negative feedback on the GnRH neurons -> less LH and FSH
Positive effect on the endometrium (gland secretion increases, contractility decreases) -> cervix closes
94
What occurs when the follicle ruptures
- Fluid leaks out and new cavity formed with blood -> bleeding -> Corpus haemorrhagicum - metoestrus phase
○ Theca interna and granulosa cells fold inwards into corpus and undergo luteinization (transformation into luteal tissue)
○ CL is mixture of large luteal cells (LLC), former granulosa cells, and small luteal cells (SLC), former theca interna cells
§ They are both steroidogenic, hence producing progesterone.
95
what are the 3 requirements for luteolysis
1) Presence of oxytocin receptors on endometrial cells
2) Presence of critical level of ovarian oxytocin
○ Oxytocin stimulates prostaglandin release from endometrium
○ Positive feedback
3) PGF2alpa synthesis by endometrium (within the uterus)
○ Binds to receptors on luteal cells -> Ca channels open -> intracellular Ca concentration increases -> high Ca is thought to cause apoptotic effects
○ Protein-kinase-C is activated which inhibits progesterone synthesis
96
Describe the hormonal changes in prooestrus and oestrus
Prooestrus:
- As P4 drops, FSH and LH increases in response to GnRH
Oestrus:
- Dominant follicles produce oestradiol and inhibin
- Inhibin suppresses FSH secretions
- Large amounts of oestradiol results in GnRH/LH surge
○ FSH doesn't surge at this point because of inhibin suppressing FSH
97
What are the 4 stages of follicle growth and what phase does this occur
Occurs in luteal phase
1) Recruitment: A cohort of follicles are selected and start growing
○ Generally if this is occurring after ovulation the high levels of progesterone will result in the death of those follicles
○ Only once a certain point in dioestrus will follicles survive due to luteolysis and subsequent decrease in progesterone
§ Therefore if give high levels progesterone before atresia occurs in 1st phase and induce luteolysis may result in ovulation before the animal was going to -> can be done
2) Selection: A few undergo atresia and some are selected
3) Dominance: one (in monotocuous species) reaches dominance and starts producing inhibin
4) Atresia: the other undergo atresia because of lack of FSH (due to negative feedback from inhibin)
98
What is the Utero-ovarian countercurrent mechanism made of, what function as and what species found in
- Made of the uterine and ovary artery
- Therefore prostaglandin goes straight from uterine artery (produced in the uterus) to the ovarian artery to be delivered to the ovaries very quickly -> without going through circulation
- Ruminants only!!!
99
What occurs to the lifespan of the CL if 1) removal of whole uterus 2) contralateral horn is removed 3) ipsilateral uterine horn is removed
1) CL stays around for the gestation length -> uterus is needed for luteolysis
2) stays the same, enough uterus to release the prostaglandin
3) it is prolonged bu tnot as long as if remove the whole uterus
