spermatogenesis and male infertility Flashcards
chromosomal make up of oocyte
22 + x
chromosomal make up of sperm
22 + y
what are the 2 primitive genital tracts
wolffian ducts (becomes vas deferens) mullerian ducts (becomes fallopian tube) every zygote starts with these - one degenerates depending on chromosomal makeup
what chromosome has the sex determining region
Y - causes testes to grow from bipotential gonad
what do foetal testes secrete
testosterone
mullerian inhibiting factors
what is androgen sensitivity syndrome
x linked recessive condition where there is congenital sensitivity to androgens (testes develop but do not descend)
presentation of androgen sensitivity syndrome
external female genetalia
presents at puberty - primary amenorrhoea and short vagina
what do undescended testes have a risk of turning into
testicular germ cell cancer
what age should undescended testes be removed before (to reduce cancer risk)
under 14
where does spermatogenesis occur
seminiferous tubules
what cells in the testes produce testosterone
leydig
why do sertoli cells form a blood-testes barrier
to prevent sperm from anti-body attack
other roles of sertoli cells
provide nutrients for developing sperm destroys defective sperm through phagocytosis
secrete seminiferous fluid
secrete androgen binding globulin
secrete inhibin and activing
role of androgen binding globulin
binds to testosterone to ensure there is a constantly high level in the lumen (testosterone essential for spermatogenesis)
action of inhibin
inhibits FSH production from anterior pituitary
action of activing
stimulates FSH production
action of FSH on sertoli cells
signals sertoli cells to produce androgen binding globulin
what controls LH and FSH release
GnRH from hypothalamus
what does LH do in males
binds to leydig cells (stimulate testosterone)
what does testosterone become before binding to androgen binding globulin
dihydrotestosterone
what type of hormone is testosterone
steroid
roles of testosterone
secondary sex characteristics
sperm production
maculinises reproductive tract in utero
what part of oocyte does sperm bind to
zona pellucida - docking
what happens after sperm has bound to oocyte
acrosome exocytosis - enzymes released to break down zona pelluicida
hypermotility of sperm to allow penetration
why is fructose present in semen
provides energy to sperm
why are prostaglandins present in semen
stimulate motility of sperm
why is semen alkaline
protect sperm against acidic vaginal environment
what is erection
blood fills cavernous cavernosa
what is emission
contraction of accessory sex glands and vas deferens - semen expelled through urethra
what is ejaculation
contraction of smooth muscles of urethra and erectile muscles
erection is sympathetic/parasympathetic
parasympathetic
ejaculation is sympathetic/parasympathetic
sympathetic
causes of male infertility
idiopathic (most common)
obstructive
non-obstructive
endocrine disorders
normal testicular volume for prepubertal males
1-3mls
normal testicular volume for adults
12-25 mls
if under what testicular volume, patient is unlikely to be fertile
<5mls
life style changes to improve male fertility
frequent intercourse (2-3x per week) <4u alcohol/day smoking cessation BMI<30 avoid tight fitting underwear less prolonged hot baths/shower use
