PHY2011 Final: PHY2011
6 Jun 2018
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à Spermatogonia are located along the basement membrane and are the first developmental stage of
spermatogenesis
à Development of Spermatozoin of spermiogenesis: final stage of spermatogenesis and no cell division occurs
• Occurs when spermatids are embedded in the luminal surface of Sertoli cells
• Spermatoza are released from Sertoli cells (remain non-motile) in process called spermiation
• Its maturation in the epididymis takes 12-21 days
à Sertoli cells play an important role – large with cytoplasm that surrounds the germ cells
Regulation of spermatogenesis and testosterone production
• GnRH are released in pulses (~ every 90 minutes) from the hypothalamus à stimulates the anterior
pituitary to secrete LH and FSH
• Leydig cells respond to LH and produces testosterone
• Sertoli cells respond to FSH and produces inhibin
• Testosterone and inhibin act as negative feedback regulators of GnRH and gonadotrophin (LH & FSH)
secretion from hypothalamus & pituitary gland
• FSH and high levels of testosterone are required for spermatogenesis
Testosterone production
• Interstitial cells lie between the seminiferous tubules
• Leydig cells are responsible for the production of testosterone
• Testosterone is a steroid and is important for spermatogenesis
• Close proximity of Leydig cells to tubules means that a local environment rich in testosterone can prevail
• Testosterone production & secretion is controlled by LH
4. Describe the role of the hypothalamus and pituitary gland in the regulation of testicular steroidogenesis
Steroidogenesis: The biological synthesis of steroids.
• Steroidogenesis in the testis is regulated by a negative feedback mechanism through the hypothalamus-
pituitary-testis axis
• Regulated by androgen
Maturation of sperm in the epididymis
• The epididymis surrounds the posterior edge of the testesandis a series of coiled tubes which:
• Monitor & adjust composition of fluid produced by the seminiferous tubules
• Acts as a recycling centre for damaged sperm
• Stores and protects spermatozoa while facilitating functional maturation
Document Summary
Spermatogonia are located along the basement membrane and are the first developmental stage of spermatogenesis. Its maturation in the epididymis takes 12-21 days. Sertoli cells play an important role large with cytoplasm that surrounds the germ cells. Steroidogenesis: the biological synthesis of steroids: steroidogenesis in the testis is regulated by a negative feedback mechanism through the hypothalamus- pituitary-testis axis, regulated by androgen. They take approximately 12-20 days to move through the epididymis, after which time, they are capable of swimming (cid:0) Immature sperm are stored in the tail of the epididymis for several months (cid:0: sperm are ejaculated from the epididymis in to the vas deferens, list several causes of male infertility, vasectomy, unknown causes, past cryptorchidism. Male infertility: about 1:20 men are sub-fertile. 50% ivf treatments for male factor infertility - intracytoplasmic sperm injection icsi: successful pregnancy now achievable in couples who previously had no prospect of fertility decline in donor insemination.
