The 2 primitive duct systems?
- The wolffian
- The mullerian
All early embryos have both
What happens in males?
The wolffian ducts progress
Mullerian ducts degenerate
What are the importance of the foetal testes?
Secrete both testosteron and mullerian inhibiting factors
Development into male or females depends upon these hormones
Stimulates by human chorionic gonadotrophin from placenta
Mullerian inhibiting factors?
Induces regression of mullerian ducts
Detailed diagram on the pathway to be female or male?
Development of the gonads?
Route of sperm
What does the testes do?
What does the scrotum do?
Sac of skin in which testes are suspended in
Secrete semen to suspend and sustain sperm
Transfer sperm to female
What percentage of testicular mass consists of highly coiled seminiferous tubules?
Where does the testes develop?
In adominal cavity of foetus
When do the testes drop into scrotal sac ?
Just before birth
Sometimes more slowly-before puberty
Individual has reached adulthood and testes have not descended
Why do the testes have to descend?
Lower body temp outside the body
Produced in Leydig cells
5 types of effects of testerone
- Before birth
- On sex-specific tissues- puberty
- On other reproductive events-sex drive
- On secondary sexual characteristics
- Nonreproductive events-anabolic hormone
Effects of testosterone on events before birth (testosterone)?
Masculinises the reproductive tract and external genitalia.
Promotes descent of the testes into the scrotum
Effects on sex-specific tissues (testosterone)?
Leydig cells secrete testerone again at puberty.
Promotes growth and maturation of the reproductive system.
Causes testes to enlarge- capable of spermatogenesis
Other reproductive effects of testosterone?
Develops libido at puberty
Can maintain it for life.
Controls GnH secretion
Effects on secondary sexual characteristics (testosterone)?
Induces male pattern of hair growth.
Enlarges larynx & thickens vocal cords.
Causes male body shape
Non reproductive events (testosterone)?
Anabolic- promotes protein and bone growth/development.
Thats why males are more muscular than females
Induces oil secretion
Sperm produced in seminiferous tubules in testes
2 types of cells used in spermatogenesis?
Sertoli cells- support spermatogenesis
Diagram of spermatogenesis?
ADD ADDITIONAL SHEET
Name the 3 stages of spermatogenesis?
- Mitotic proliferation
- Meiotic division
Divides 3 times before forming primary spermatocytes (46 chromosomes)
1st meiotic divison: each primary spermatocyte divides into 2 haploids (secondary spermatocytes)
2nd meiotic divison: secondary spermatocytes divide to form 2 single-strande spermatids.
When is testosterone required for spermatogenesis
During mitosis and meiosis stages
Spermatides converted to spermatozoa.
FSH is required for this process
Structure of the sperm?
Acrosome contains enzymes for penetration of ovum.
Nucleus: contains genetic material
Tail: for motility
How many days does spermogenesis take?
Name the 6 roles of the sertoli cells?
- Form a blood-testes barrier (tight junctions to protect the pserm from antibody attack)
- Provide nutrients for the developing cell
- Phagocytosis (removes unneeded compounds)
- Secrete seminiferous tubule fluid (used to carry cell along pressure gradients)
- Secrete androgen binding protein (binds testosterone for sperm production)
- Secrete inhibitin (regulates FSH)
What do the sertoli cells secrete?
Mullerian inhibiting factor (MIF)
Name the 2 gonadotropic hormones that control the testes?
Both produced by the anterior pituitary
LH (acts on leydig cells- regulates testosterone secretion)
FSH (acts on sertoli cells to enhance spermatogenesis)
Both are stimulated for secretion by GnRH
What does the testis do?
Produce sperm and secrete testosterone.
Located in the scrotum
Epididymis and ductus deferens?
Serve as the sperms exit route from the testis.
The site for maturation of the sperm for motility and fertility.
Concentrate and store the sperm before release
Supply fructose to nourish the ejaculated sperm.
Serete prostaglandins that stimulate motility to help transport the sperm within the male and female.
Provide the bulk of the semen.
Provide precursors for the clotting of semen
What does the prostate gland do?
Secretes an alkaline fluid that neurtralises the acidic vaginal secretions.
Triggers clotting of the semen to keep the sperm in the vagina.
What does the bulbourethral gland do?
Secrete mucus for lubrication
What happens in the hormonal sense during puberty?
Androgen secretion from the adrenal cortex. This stimulates testicular enlargement and public hair growth.
Tests mature and produce androgen and sperm triggered by FSH and LH. What triggers GnRH production is not clear
2nd sexual characterisitics that occur during puberty?
Appear due to the testosterone and metabolites.
Growth of larynx- deepening of voice
Increased bone mass- increasing mass and strenth
Thickened skin- increased and thickened hair.
How long does it take for somatic growth to finish (puberty)?
What hormones induce this growth?
Induced by gonadal sex steroids, growth hormone and insulin-like growth factor.
Pubery last many year: not fully mature until 20-25 yo.
Name the 6 essential role female reproductive system function?
- Production of ova
- Reception of sperm
- transport of sperm and ova to site of fertilisation
- Nourishment of the infant by lactation
What do the ovaries do?
Maturation and release of ova
What does the oviducts (fallopian tubes) do?
Site of fertilisation
What does the uterus do?
Maintains foetus during gestation
Expels foetus at end of gestation
What does the cervix do?
Has a small opening to allow sperm through to uterus
Expands greatly during birth
What does the vagina do?
Receptacle for sperm.
What does the vaginal opening do?
Allow penis in
Allow baby out
What does female external genitalia do?
No physiological involvement in reproduction
Involved in stimulation
Identical meiotic and mitotic division to male sperm production
oogenesis tkes many years
Begins in utero
Suspended for many years
Begins again at puberty
Complete meiosis 2 at fertilisation
What happens during menopause?
Because all the ovums are produced before birth and none are made during your life there is only a limited number of eggs.
Menopause is when there is no eggs left and oogenesis ceases.
Stages of oogonesis?
See additional sheet
Stages of oogenesis?
One oogonium goes through mitosis to produce lots of primary follicles with 46 chromosomes.
Starts mieosis but is suspended in the prophase stage until puberty
What happens in oogenesis?
The primary oocyte enlarges and finishes the first meiosis phase making the first polar body and secondary oocyte.
The secondary oocyte undergoes meiosis 2 but is suspended in the metaphase stage until fertilisation. This produces the mature ovum and a secondary polar body.
What does the polar body contain?
How many are produced?
4 in total are produced.
Contains have the chromosomes but very little cytoplasm.
Ovarian cycle lasts?
28 days averagely
What are the 2 phases of ovarian cycle?
1st half of cycle.
Maturation of egg, ready for ovulation at midcycle
2nd half of cycle
Development of corpus luteum
Induces preparation of reproductive tract for pregnancy
What day averagely does ovulation take place?
What does the corpus luteum do?
keep the levels of progesterone high before the placenta can take over
Primary follicle characteristics?
Before birth, the primary oocyte is surrounded by a single layer of granulosa cells. This strucutre is called a primary follicle
2 million at birth (decrease after each cycle)
Until puberty: all 1st generation follicle degenerates to scar tissue and after puberty 2nd generation follicles develop cyclically.
Oocyte grows and follicle expands.
Becomes differentiated under hormonal influence.
After puberty, about 0.02% will be ovulated the rest will undergo atresia
What is atresia?
Degeneration of some follicles into scar tissue
The luteal phase?
Follicular cells left behind after ovulation undergo luternisation.
Transformation to the corpus luteum
Secretes progesterone and oestrogen
Oestrogen secreted in follicular phase and progesterone secreted in luteral phase. Essentail for preparation of uterine lining for implantation.
After ovulation, corpus luteum grows for 8-9 days.
No fertilisation: will not survive longer than 14 days.
Degeneration of corpus luteum signals start of a new follicular pahse.
What happens to the corpus luteum if fertilisation occurs?
Corpus luteum persists
Produces increasing quantities of progesterone and oestrogen
Hormone control over ovarian cycle?
See additional sheet
What hormones cause the oocyte to mature and eventually the maturation of corpus luteum?
LH and FSH
What causes the maturation of the endometrium?
Estrogen and progesterone.
See additional sheet
What does menstruation mark?
The beginning of both uterine and ovarian cycle
During the first 12 days of the ovarian cycle estrogen does?
It exerts negative feedback on gonadtropin release
Decrease levels of FSH and LH
What does estrogen do during day 12-14 ?
Exerts its positive feedback on the pituitary
Increase levels of FSH and LH
What triggers ovulation
Surge in LH
What are estrogen and progesterone important for?
The maintenance of the uterine lining
Send negative feedback to the anterior pituitary.
What would happen if no progesterone was produced?
The uterine lining sloughs off
what happens when there is a decrease in estrogen and progesteron?
Relieves its neative feedback on the anterior pituitary
GnRH , FSH and LH increase.
New ovarian cycle
Age 6-8 yo.
Adrenal gland secretes androgens.
Eventually cause growth spurt ad public hair stars
Breast development starts
onset of menstrual cycle
Increase FSH and LH from pituitary
Ovaries producing steroids.
What happens to the epiphseal plates during puberty?
Because of estrogen in females and testosterone in males.
FSH levels rise.
Ovarian oestrogen, progesteron and inhibin fall.
Cessation of ovulation and menstruation Hot flushes.