Equine Anatomy > Reproductive System > Flashcards

Reproductive System Flashcards

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1
Q

What is the function of the female reproductive system?

A

-Pregnancy
-Delivery of foal
-Hormone production
-Protection from infection

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2
Q

How is the mare reproductive system protected from infection?

A

Vulva positioned vertically and to the pelvic floor and the lips form a seal so feces/air cannot enter the repro tract. The collapsed walls of the vagina also prevent contamination. Finally, a tight cervix prevents contamination.

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3
Q

Why is it a problem when the vulva is tilted to far?

A

Pneumovagina can occur and contaminate the vagina/uterus

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4
Q

vestibule

A

caudal portion of the vagina

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5
Q

urethral orifice

A

opening through which urine is expelled for mares; located on the floor of the vestibule

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6
Q

transverse fold

A

separates the vestibule and vaginal vault of the vagina

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7
Q

vaginal vault

A

cranial portion of the vagina

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8
Q

What changes in the mare repro system can result in urovagina?

A

-Transverse fold loses function, making it easier for urine to get into the vaginal vault
-uterus sinks ventral to pelvic brim, making it harder for urine to be expelled by gravity
-poor vulva conformation (tilted more horizontal) can make it harder for urine to escape the vulva

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9
Q

cervix

A

muscular constriction between the uterus and vagina

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10
Q

What are the functions of the cervix?

A
  1. during pregnancy, tight/white/mucus plug to prevent contamination of the fetus
  2. during estrus/foaling, melted/soft/pink to make it easier for sperm to reach the ampulla or for foal to exit repro tract
  3. during diestrus, tight/white to prevent contamination of possible fetus
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11
Q

uterus

A

hollow, muscular organ

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12
Q

what are the 2 parts of the uterus?

A

uterine horns and uterine body

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13
Q

what is the function of the uterus?

A

where the foal occupies/grows during pregnancy

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14
Q

what are the 3 uterine layers?

A
  1. perimetrium- outermost layer
  2. myometrium- muscular layer needing for foaling/cleaning out uterus
  3. endometrium- contains immune cells to clean uterus from sperm cells/debris
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15
Q

What are the 3 parts of the oviduct?

A
  1. isthmus
  2. ampulla
  3. infundibulum
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16
Q

oviduct

A

passageway from ovary to the uterus

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17
Q

what section of the oviduct is the site of fertilization?

A

ampulla

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18
Q

what is the function of the infundibulum?

A

collects the egg

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19
Q

what is the function of the isthmus?

A

stores sperm prior to fertilization; sperm can live from 6-12 hours to days

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20
Q

ovaries

A

found under the ilium wings; keeps genetic material of the mare, matures eggs, and releases hormones

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21
Q

what are the ovaries suspended by?

A

broad ligament

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22
Q

How are a mare’s ovaries different a cow’s?

A

Mare: from outermost to innermost, tunica albuginea, medulla, cortex; follicle migrates to ovulation fossa and can only ovulate there

Cow: from outermost to innermost, tunica albuginea, cortex, medulla; can ovulate anywhere on the ovary

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23
Q

Why can a mare’s follicles not be visibly seen like in a cow?

A

The mare’s cortex layer is the innermost layer, so the follicles growing in the layer cannot be seen from the outside. The cow’s cortex layer is the outermost layer, so the follicles growing can be seen.

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24
Q

Graafian follicle

A

accumulates fluid until ovulation; preovulatory follicle; active during follicular phase; the most dominant follicle

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25
Corpus hemorrhagicum (CH)
bloody; occurs right after ovulation; where the follicle ruptured to release the oocyte
26
Corpus luteum (CL)
produces progesterone and keeps the mare out of estrus; if pregnant, it supports the pregnancy; active during luteal phase
27
Corpus Albicans (CA)
white, mostly a scar; where the CL has regressed; forms when the CL regresses when the mare is not pregnant
28
What does it mean by a mare being seasonally polyestrous?
the mares are in season several times during the warm months of the year; they are regulated by changes in day length, i.e. summer months are longer days than winter months
29
Define natural breeding season.
During the summer months; rhythmic cycling of hormones
30
Define anestrous.
during the winter months; the mare is not cycling
31
Define transition period.
hormones and cycles are unpredictable; ovulation failure; during the fall and spring seasons; hard to breed mare during this time
32
estrous
period of predictable, rhythmic cycling of hormones during the summer
33
anestrous
period where the mare is not cycling during the winter
34
What is the difference between estrous and estrus?
Estrous = 21 day cycle of mares, which includes estrus and diestrus Estrus = sexual receptivity of the mare to the stallion; lasts ~4-7 days; is during the follicular phase where a Graafian follicle is developing and preparing to ovulate
35
What are signs of estrus in mares?
squatting, alert ears, tail raised in relaxed motion and held to one side, frequent urination in small amounts, winking, and sexual receptivity to the stallion
36
What are signs of diestrus in mares?
agitated, twitching of the tail, ears pinned, may bite/strike/kick the stallion, forcefully squirt urine; does not want to be bred
37
estrogen
released by follicles; occurs during estrus and causes signs of heat
38
What hormone does melatonin block?
GNRH, or gonadotropin releasing hormone
39
GNRH
levels increase when melatonin is blocked; released from the hypothalamus, causing the release of the gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland
40
Where are FSH and LH released from? What causes them to be released?
released from the anterior pituitary gland; released by GNRH
41
FSH
follicle-stimulating hormone; causes follicles to grow on the ovary; released from anterior pituitary gland
42
LH
luteinizing hormone; causes follicles to ovulate; released from anterior pituitary gland
43
progesterone
P4; maintains mare's pregnancy or keeps mare out of estrus; released by CL on the ovary
44
prostaglandin F2 alpha
PGF2a; released at the end of diestrus by the uterus IF the mare is NOT pregnant; causes regression of the CL and restarts the estrus cycle
45
what structure produces estrogen?
Graafian follicle
46
what structure produces progesterone?
CL
47
during what phase is melatonin produced?
anestrus
48
where is melatonin released from?
the pineal gland
49
List the pathway that an ovum would pass through before being born.
Ovaries, Infundibulum, ampulla, isthmus, uterus (uterine horn, uterine body), cervix, vagina (vaginal vault, transverse fold, vestibule), vulva
50
What are the 3 parts of the testis?
1. seminiferous tubules 2. rete testis 3. efferent ducts
51
What are the 3 parts of the epididymis?
1. caput 2. corpus 3. cauda
52
What are the 4 accessory sex glands in stallions?
1. ampulla 2. seminal vesicles/vesicular glans 3. prostate gland 4. bulbourethral gland
53
what are the 2 portions of the male urethra?
pelvic and penile
54
what are the 3 parts of the penis?
1. root 2. body 3. glans penis
55
What are the 2 functions of the male gonad?
spermatozoa and testosterone production
56
What are the layers of the scrotum?
a. skin b. tunica dartos c. tunica vaginalis - parietal layer d. space e. tunica vaginalis - visceral layer f. tunica albuginea
57
What 3 structures are part of the spermatic cord that anchors the testes to the abdomen?
a. pampiniform plexus b. ductus deferens c. cremaster muscle
58
What structures are involved in thermoregulation of the testicle? How do they contribute?
1. skin - sweat glands to cool down 2. tunica dartos - shrivel to warm 3. cremaster muscle - pushes testes closer to abdomen to warm 4. pampiniform plexus - counter-current mechanism
59
Explain the countercurrent mechanism in the testes.
Found in the pampiniform plexus, there are a net of veins containing cooled blood coming from the testis surrounding warmer blood coming from the body. This cooler blood helps cool down the warmer blood coming from the body.
60
What part of the testis conduct spermatogenesis? What cells are within the seminiferous tubules?
seminiferous tubules Sertoli cells
61
What part of the testis conduct testosterone production? What cells are within this part?
Interstitial tissue Leydig cells
62
What hormone stimulates Sertoli cells to support sperm cells?
FSH, or follicle stimulating hormone
63
What hormone stimulates Leydig cells to produce testosterone?
LH or luteinizing hormone
64
Sertoli cells
support spermatogenesis and produce estrogen
65
What is the function of the hemato-testicular barrier?
prevents blood/ immune system from reaching sperm cells
66
What is the function of the caput and corpus of the epididymis?
sperm cell maturation
67
What is the function of the efferent ducts?
connect testes to epididymis and reabsorb testicular fluid
68
What is the function of the cauda of the epididymis?
storage of mature/fertile spermatozoa
69
What does cryptorchid mean? Why is it a problem?
one or both testes remains in the abdominal cavity after failing to descend; unilateral is where one fails and bilateral is where both fail to descend The Sertoli cells die because the body cavity is too hot/sperm not produced. The horse will still produce testosterone, causing behavioral issues.
70
Ductus deferens
connects cauda of epididymis to ampulla
71
Ampulla
paired dilation of the ductus deferens; only accessory sex gland that sperm actually travels through; provides activation fluid for sperm
72
What are the 4 accessory sex glands in stallions?
a. ampulla b. vesicular glands/seminal vesicles c. prostate gland d. bulbourethral glands/Cowper's glands
73
Vesicular glands/seminal vesicles
adds nutrients/energy to sperm; provides the gel that seals the cervix
74
Prostate
provide pH buffers/lubrication that cleans/protects sperm
75
bulbourethral glands
lubricate/neutralize the urethra
76
Where do the vesicular glands/prostate/bulbourethral glands enter the reproductive tract?
openings in dorsal urethra
77
What muscles connect the root of the penis to the ischium? What is their function?
ischiocavenousus muscles; provides stability and blocks blood from coming backwards to keep the stallion erect
78
Corpus cavernosum
area of the penis that initially becomes engorged with blood to cause erection
79
Corpus spongiosum
surrounds urethra; stabilizes urethra and keeps erection from compressing it; tip of the penis is surrounded by this tissue; becomes engorged later to keep stallion locked in the mare
80
Bulbospongiosum
rhythmically contracts like a wave to push urine/semen out of the urethra
81
What four structures make up the body of the penis?
corpus cavernosum, urethra, corpus spongiosum, bulbospongiosum
82
retractor penis muscle
keeps penis inside shaft when not erect; relaxes during erection
83
glans penis
tip of the penis where corpus spongiosum covers corpus cavernosum and ends
84
urethral process
end of urethra where urine/semen exit stallion
85
preputial folds
contain glands that produce smegma
86
GnRH produced by the hypothalamus in stallions causes what two hormones to be released from the anterior pituitary?
FSH, follicle stimulating hormone, and LH, luteinizing hormone
87
What does FSH cause in stallions?
acts on Sertoli cells to increase spermatogenesis
88
What does LH cause in stallions?
acts on Leydig cells to increase testosterone and estrogen production
89
What does inhibin inhibit in stallions? What is it released by?
released by Sertoli cells and acts on anterior pituitary to inhibit FSH production, thereby inhibiting spermatogenesis; negative feedback mechanism
90
What does testosterone/estrogen act on for negative feedback? What cells release these hormoness?
released by Leydig cells and acts on anterior pituitary to inhibit LH and acts on hypothalamus to inhibit GnRH
91
What does testosterone do?
responsible for secondary sexual characteristics, sexual arousal, erection/ejaculation, development/function of accessory sex glands, and body growth
92
List the pathway of sperm through the stallion reproductive tract.
1. testis (seminiferous tubules, rete testis, efferent ducts) 2. Epididymis (caput, corpus, cauda) 3. ductus deferens 4. ampulla 5. urethra (pelvic and penile) 6. urethral process
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