male reproductive physiology Flashcards
why do the testicles lie outside of the body
the temperature required for sperm production is lower than that of the body (1-2 degrees lower than the abdominal cavity in the scrotum)
path of sperms following production
produced in the testes
pass through the epididymis
travel through the vas deferens to the seminal vesicles
secretions from the prostate gland and seminal vesicles are added to the sperm
exit the body through the urethra
what is the role of the epididymis
storage site for sperm
sperm stay there for ~3mths while they mature
structure of the testes
divided into several lobules
seminiferous tubules are within the lobules
testes are surrounded by a fibrous capsule
what is the name for the fibrous capsule covering the testis
tunica albuginea
penetrates into the structure of the testis and divides it into several lobules
what is the site of sperm production
seminiferous tubules in the testis
where do the sperm travel after they have been produced in the seminiferous tubules
rete testis
this is where all the outflow of the seminiferous tubules merge and lead into the head of the epididymis
what are the 3 parts of the epididymis
head
body
tail
where does the vas deferens emerge
tail of the epididymis
what are the 3 types of cells within the seminiferous tubule and what are their functions
germ cells - produce sperm
sertoli/sustentacular cells - support sperm producing cells, produce inhibin
interstitial (Leydig) cells - surround the seminiferouos tubules and produce testosterone
what are the 2 main functions of the testis
sperm production - avg time from production to ejaculation = 64 days
testosterone production - male 2y sexual characters, controls spermatogenesis
endocrine control of testicular function
reproductive hormones
GnRH from hypothalamus
gonadotropins - FSH and LH from ant pituitary
testosterone from testicles
interaction of hormones on testes
hypothalamus releases GnRH
acts on ant pituitary to release FSH + LH
FSH - Sertoli cells facilitate Spermatogenesis
LH - Leydig cells, +ve feedback on spermatogenesis
sertoli cells release inhibin - -ve feedback on ant pituitary
Leydig cells produce testosterone - -ve feedback on ant pituitary and hypothalamus
define spermatogenesis
sperm production from the priomordial germ cells in the seminiferous tubules
length of avg cycle of spermatogenesis
64 days
germ cells pass through different developmental stages
mature sperm cells are produces
what are the 2 distinct phases in spermatogenesis
spermatocytogenesis
spermiogenesis
what is spermatocytogenesis
clonal expansion and maturation through mitotic and meiotic processes
what is spermiogenesis
differentiation into mature sperm cells
when does spermatogenesis begin
starts at puberty
continues lifelong
steps of spermatocytogenesis
CLONAL EXPANSION spermatogonia A mitosis spermatogonia B MATURATION spermatocyte I meiosis I spermatocyte II meiosis II spermatid DIFFERENTIATION spermatid sperm
chromosomal division during spermatogenesis
mitosis - spermatogonium –> 1y spermatocyte, duplication, diploid chromosomes (46)
meiosis 1 - 1y spermatocyte —> 2y, 2 cells w/ haploid chromosome number
meiosis 2 - 2y spermatocyte –> spermatid, 2 cells w/ haploid chromosome
spermiogenesis - maturation of spermatids into functional sperm cells
what factors affect spermatogenesis
medical
lifestyle
combination
can ultimately affect male fertility
medical factors affecting spermatogenesis
pretesticular - problem with the hormonal control
testicular - problem at the site of production
pretesticular medical factors affecting spermatogenesis
functional - XS weight loss/gain, stress intracranial tumours, cysts, bleed prolactinoma medications - opiates, external testosterone, steroid (body building) genetic - Kallmann's syndrome
testicular medical factors affecting spermatogenesis
surgery - orchidectomy, orchidopexy STI mumps orchitis testicular trauma or torsion radio/chemotherapy genetic - Klinefelter's (46 XXY), Y chromosome microdeletion, CF
lifestyle factors affecting spermatogenesis
effect from mother during pregnancy - irreversible
effects from father’s sperm - reversible
smoking - heavily impacts production and functional capacity of sperm
obesity
occupational and environmental chemical exposure
steps to reduce the impact of factors affecting fertility (5)
improve lifestyle - normal BMI, stop smoking, alcohol in recommended limits
healthy diet, exercise, adjustments to occupational exposure
optimise underlying medical condition
stop medications/switch to alternative pregnancy compatible medications
reduce STI risk and treat promptly
fertility preservation - sperm freezing prior to surgery or cancer treatment
define oligospermia
low sperm count
past fertility - things that could affect sperm count
puberty - delayed
previous children/fertility
personal/FHx of genetic problems
previous fertility treatment
things that could affect sperm count - androgen deficiency symptoms
infrequent shaving
unable to grow beard
low libido
erection/ejaculation difficulty
things that could affect sperm count - medical problems current/past
systemic disease
malignancy
prolactinoma
things that could affect sperm count - genitourinary hx
STI mumps orchitis testicular trauma/torsion undescended testis recurrent UTI
things that could affect sperm count - past surgery
inguinal hernia repair
orchidopexy
orchidectomy
things that could affect sperm count - medications
high dose steroid
testosterone replacement
supplements:
body building products - exogenous steroids
things that could affect sperm count - occupation
exposure to chemicals, heavy metals, radiation
things that could affect sperm count - lifestyle
sedentary food habits smoking obesity alcohol recreational drug use
examination/investigations for low sperm count
BMI genital examination USS testis hormonal profile genetic test
why is it important to palpate the vas deferens
may discover absent vas deferens which is a feature of CF
genital examination for low sperm count
external genitalia, testicular size, palpation of vas deferens, inguinal hernia, varicocele
hormonal profile for low sperm count
FSH
LH
testosterone
prolactin
genetic test for low sperm count
karyotype
Y chromosome microdeletion
hypogonadotropic hypogonadism in men
low FSH, LH, prolactin, testosterone
hypothalamus or pituitary cause
prolactinoma and fertility
high prolatcin
low sperm count
hypergonadotropic hypogonadism in men
high FSH, LH
low testosterone
testicular cause
things to look for in US of testes
testicular volume
hydrocele
varicocele
cancer
