what is the SRY gene?
Sex determining region located on the Y chromosome
- present in males
- abscent in females
what does presence of the SRY gene cause?
-causes primodial germ cells to differentiate into steroli and leydig cells
once induced what do leydig cells produce? what affect does it have?
-production of testosterone
causes the wolffian duct to differentiate into
- epididymis
- vas deferens
- seminal vesicles
- ejaculatory duct
conversion of testosterone to dihydrotestosterone in target tissues cause
-development of penis, scrotum and prostate
once induced what do steroli cells produce? what effect does it have?
produces MIF (mullerian inhibiting factor)
causes the mullerian duct to degenerate
What happens in the absence of SRY cause?
causes primordial germ cells to differentiate into the fetal ovaries
Once induced what do the presence of fetal ovaries cause?
absence of MIF
-mullerian duct differentiates into uterus, fallopian tubes and inner vagina
absence of testosterone
- wolfian duct degenerates
- development of out vagina and external genetial
what physiological changes take place at menopause?
- weight gain
- heavy night sweats
- heart palpitations
- headaches
- hot flushes
- skin tingles, itching, dryness and thinning
- joint stiffness and soreness
- back pain
- urinary incontinence
- urgency
- vaginal dryness and painful intercourse
- a whole onslaught of psychological changes
describe the process of oogenesis.
- all germ cells (oognia) undergo mitosis and become primary oocytes
- primary oocytes start meiosis 1 but become in a state of meiotic arrest after DNA replication
- LH surges in puberty causes primary ooctye to finish meiosis 1 and become a secondary oocyte in meotic arrest and the 1st polar body
- if the oocyte is fertilised it completes secondary meiosis and generates a secondary polar body
describe the process of spermatogenesis.
- mitosis of germ cells gives A & B spermatogonium
- B spermatogonium passes through the BTB and becomes a primary spermatocyte
- primary spermatocyte undergoes meiosis 1 giving a haploid chromosome number becoming a secondary spermatocyte
- spermatocyte undergoes meiosis to giving rise to a spermatids
where does spermatogenesis take place?
in the seminiferrous tubules
what happens to A spermatogonia after mitosis of a germ cell? why?
- it remains as a spermatogomiun and continues normal mitosis
- so all germ cells aren’t lost and the process of spermatogensis can carry on taking place
describe the process of spermiogensis.
where does it take place?
- takes place on the appical side of steroli cells
- spermatids lose excess cytoplasm to become lighter
- sprouts tail - stereocilla
when differentiated steroli cell cytoplasm moves to release sperm into the lumen
what three physiological changes occur at puberty?
- increase hypothalamic secretions
- increase levels of LH, FSH and sex steroids
- Increase levels of growth hormone
what physical changes take place at puberty for girls?
- 1st sign = breast development
- public and axillary hair growth
- growth spurt
- menarche (first menstruation 2,5 years after the start of puberty)
- acne, body odor and mood changes
what physical changes take place at puberty for boys?
- 1st sign testicular enlargement
- pubic, axillary and facial hair growth
- growth spurt
- spermatogensis starts
- acne, body odor and mood changes
what forms the blood testes barrier?
tight junctions between steroli cells
