Male Reproductive Endocrinology Flashcards
How long does it take for a spermatogonia to become a mature sperm?
64 days
When, in the lifetime of a male, does spermatogenesis start and end?
Starts at puberty ends at death
Where does spermatogenesis take place?
Testis
Which cells exist in the interstitial of the testis, between the tubules, and what is the function of these cells?
Leydig cells - produce testosterone
Where in the testis do sertoli cells exist?
In the periphery of the tubules
Describe the mitosis stage of spermatogenesis?
A dark a spermatogonia divides to form another dark a cell which will remain as a stem cell and a pale a cell which will become a b spermatogonia which then becomes a primary spermocyte
What are the products of meiosis one and two during spermatogenesis?
Meiosis one produces primary spermatocytes
Meiosis two produces secondary spermatocytes
What changes occur in the differentiation of spermatids to spermatozoa?
Elongation of cell
Development of tail
Formation of acrosome
Cytoplasmic remodelling - large portion of cytoplasm is lost
During differentiation to form a spermatozoa, a residual body of cytoplasm is lost from the cell. What happens to this residual body?
It is phagocytosed by sertoli cells
Where in the tubule of the testis do the immature spermatogonia exist as compared to the mature spermatozoa?
The least mature cells exist on the peripheral edge of the tubule with the cells becoming more mature until you eventually reach the spermatozoa on the luminal surface
What is the purpose of the acrosome of a spermatozoa?
To contain enzymes to allow penetration of the ovum
What cell organelle is particular prevalent in The midpiece of a spermatozoa?
Mitochondria
Describe the role of the hypothalamus/anterior pituitary/gonadal axis in the control of spermatogenesis?
GnRH from hypothalamus stimulates the release of LH and FSH from anterior pituitary. These stimulate leydig cells to produce testosterone and this testosterone alongside FSH stimulates sertoli cells to promote spermatogenesis. Once spermatogenesis reaches sufficient levels, sertoli cells produce inhibin which limits FSH production and decreases spermatogenesis
How does exposure to phthalates effect males?
Males exposed to phthalate in foetal stage sae major reduction in testosterone production, abnormal testis development and decreased germ cell numbers with delayed differentiation
What four symptoms comprise testicular dysgenesis syndrome?
Crytorchidism
Hypospadias
Infertility
Germ cell cancers
How do anabolic steroids affect the male reproductive system?
These have a mild testosterone like effect so if taken in large amounts can have a negative feedback effect on the hypothalamus resulting in reduced secretion of GnRH and thus reduced secretion of FSH and LH leading to testis atrophy and sterility
What affect do phytoestrogens have om the reproductive system?
Oestrogenic effect
Affects male sex behaviour if exposed in development
Reduced fertility
Diesthylstilbestrol is a synthetic oestrogen which was used to block spontaneous abortion and promote foetal growth. Why was this drug later banned?
It had a negative effect on reproductive development and lead to increased incidence in vaginal cancers in the children
What are endocrine disruptors?
Exogenous substances which disrupt normal endocrine function
How might endocrine disrupters exert their effect on the body?
By acting as agonist to promote too much hormone activity or inappropriate hormone activity
Acting as antagonists to prevent normal hormone action
Interfering with normal metabolism to prevent to synthesis or breakdown of natural hormones
Which enzyme converts testosterone to dihydrotestosterone?
5 alpha reductase
What is the role of androgen binding protein in spermatogenesis?
It binds to and concentrates testosterone and dihydrotestosterone in the testes
