Male Reproductive Endocrinology

Question 1

How long does it take for a spermatogonia to become a mature sperm?

Answer 1

64 days

Question 2

When, in the lifetime of a male, does spermatogenesis start and end?

Answer 2

Starts at puberty ends at death

Question 3

Where does spermatogenesis take place?

Answer 3

Testis

Question 4

Which cells exist in the interstitial of the testis, between the tubules, and what is the function of these cells?

Answer 4

Leydig cells - produce testosterone

Question 5

Where in the testis do sertoli cells exist?

Answer 5

In the periphery of the tubules

Question 6

Describe the mitosis stage of spermatogenesis?

Answer 6

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

Question 7

What are the products of meiosis one and two during spermatogenesis?

Answer 7

Meiosis one produces primary spermatocytes

Meiosis two produces secondary spermatocytes

Question 8

What changes occur in the differentiation of spermatids to spermatozoa?

Answer 8

Elongation of cell
Development of tail
Formation of acrosome
Cytoplasmic remodelling - large portion of cytoplasm is lost

Question 9

During differentiation to form a spermatozoa, a residual body of cytoplasm is lost from the cell. What happens to this residual body?

Answer 9

It is phagocytosed by sertoli cells

Question 10

Where in the tubule of the testis do the immature spermatogonia exist as compared to the mature spermatozoa?

Answer 10

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

Question 11

What is the purpose of the acrosome of a spermatozoa?

Answer 11

To contain enzymes to allow penetration of the ovum

Question 12

What cell organelle is particular prevalent in The midpiece of a spermatozoa?

Answer 12

Mitochondria

Question 13

Describe the role of the hypothalamus/anterior pituitary/gonadal axis in the control of spermatogenesis?

Answer 13

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

Question 14

How does exposure to phthalates effect males?

Answer 14

Males exposed to phthalate in foetal stage sae major reduction in testosterone production, abnormal testis development and decreased germ cell numbers with delayed differentiation

Question 15

What four symptoms comprise testicular dysgenesis syndrome?

Answer 15

Crytorchidism
Hypospadias
Infertility
Germ cell cancers

Question 16

How do anabolic steroids affect the male reproductive system?

Answer 16

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

Question 17

What affect do phytoestrogens have om the reproductive system?

Answer 17

Oestrogenic effect
Affects male sex behaviour if exposed in development
Reduced fertility

Question 18

Diesthylstilbestrol is a synthetic oestrogen which was used to block spontaneous abortion and promote foetal growth. Why was this drug later banned?

Answer 18

It had a negative effect on reproductive development and lead to increased incidence in vaginal cancers in the children

Question 19

What are endocrine disruptors?

Answer 19

Exogenous substances which disrupt normal endocrine function

Question 20

How might endocrine disrupters exert their effect on the body?

Answer 20

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

Question 21

Which enzyme converts testosterone to dihydrotestosterone?

Answer 21

5 alpha reductase

Question 22

What is the role of androgen binding protein in spermatogenesis?

Answer 22

It binds to and concentrates testosterone and dihydrotestosterone in the testes