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Reproductive Physiology of the Male (Puberty (highly sensitive -ve…
Reproductive Physiology of the Male
Functional anatomy
consists of many individual organs
acting in concert producing spermatozoa
involve neuroendocrine & genital system
2 testes
suspended within scrotum
pivotal organ
functions influenced by neuroendocrine system
interstitial tissue compartment
basal compartment
contain spermatogenia
adluminal compartment
steroidgenesis
production of androgens in Leydig cell
spermatogenesis in seminiferous tubule
temperature dependant
lengthy orchestrated process
diploid stem cells divide by mitosis
to maintain their own number
cyclically produce progeny that undergo meiotic division & differentiation into haploid spermatids
release as spermatozoa
3 major events
spermatocytogenesis
mitotic division of type A spermatogonia
population of stem cell is maintained
type A become type B
meiosis
only during processes of oogenesis & spermatogenesis
spermiogenesis
newly formed spermatids continue to differentiate without dividing forming mature spermatids
formation of acrosome
condensation & elongation of nucleus
formation of flagellum
extensive shedding of cytoplasm
require high local concentrations of androgens within testis
penis
copulatory organ
erection
surrounded by tunica albugenia
Emission
release of spermatozoa & accessory gland fluid into pelvic urethra
sympathetically mediated thoracolumbar reflex contraction
Ejaculation
forceful expulsion of semen from urethra
parasympathetically mediated sacral reflex
Hypothalamic-pituitary-testiscular axis
reproductive system is regulated by hypothalamus, anterior pituitary and testes
hypothalamus
synthesise & secrete GnRH
in pulsatile manner
acts directly on gonadotropic cells in pituitary
synthesise & secrete FSH & LH
LH binds to membrane receptors on Leydig cell
stimulates them to convert cholesterol to testosterone
Puberty
able to produce sufficient numbers of sperm to impregnate female
not same with sexual maturity
results from a continuous process of endocrine changes that are initiated shortly after birth
highly sensitive -ve-feedback mechanism
low level of gonadotropin secretion rapidly decreases when sex steroids are admninstered
Anabolic steroid
androgen derivatives that have been altered to maximize anabolic reaction and minimize androgenic side effects
undesirable side effects
affects pituitary function
leads to long-lasting impairment of testicular endocrine function
may lead to incomplete development of hypothalamic-pituitary-gonadal axis
reduce seminal quality, daily sperm output & production, and testicular size
result from negative-feedback mechanism on Gn release from pituitary