Male Reproductive Physiology

Question 1

What is included in the male reproductive organs?

Answer 1

Testes, epididymis, ductus deferens, prostate gland, bulbourethral gland and penis

Question 2

Describe the normal process of ejaculation

Answer 2

Sperm are created in testes
Sperm travels through vas deferens to urethra
Seminal vesicles and prostate crate semen - carried along with sperm in urethra

Question 3

Describe the structure of the testes

Answer 3

Tunica albuginea - fibrous capsule
Seminiferous tubules - lobules
Head, body and tail of epididymis
Vas deferens

Question 4

What are the three types of cells within the seminiferous tubules?

Answer 4

Germ cells
Sertoli/ sustentacular cells
Interstitial (Leydig) cells

Question 5

What do germ cells produce in males?

Answer 5

Sperm

Question 6

What do sertoli/ sustentacular cells produce?

Answer 6

Support sperm producing cells
Produce inhibin

Question 7

What do interstitial (Leydig) cells produce?

Answer 7

Testosterone

Question 8

What are the function of testes?

Answer 8

Sperm production
Testosterone production

Question 9

What is the average time from production of sperm to ejaculation?

Answer 9

64 days - average cycle is 3 months
Millions of viable sperm are produced per day

Question 10

What does testosterone production control?

Answer 10

Spermatogenesis

Question 11

What are the reproductive hormones involved in the endocrine control of testicular function?

Answer 11

GnRH produced from hypothalamus
Gonadotrophins - FSH and LH from anterior pituitary
Testosterone from testes

Question 12

What is the role of FSH on the testes?

Answer 12

Sperm cells facilitate spermatogenesis

Question 13

What is the role of LH on the testes?

Answer 13

Leydig cells to produce testosterone

Question 14

Describe the negative feedback effects in endocrine control of testes

Answer 14

Testosterone and inhibin inhibit secretion of GnRH by the hypothalamus
LH and FSH inhibits by the pituitary

Question 15

What are the 2 stages of spermatogenesis?

Answer 15

Spermatocytogenesis
Spermiogenesis

Question 16

When does the process of spermatogenesis start?

Answer 16

Starts at puberty and is lifelong

Question 17

Describe spermatocytogenesis

Answer 17

Clonal expansion and maturation through mitotic and meiotic process

Question 18

Describe spermiogenesis

Answer 18

Differentiation into mature sperm cells

Question 19

What processes are involved in the clonal expansion and maturation of spermatocytogenesis?

Answer 19

1 mitotic and 2 meiotic divisions
Leads to spermatids being produced

Question 20

What is the end result of spermiogenesis?

Answer 20

Sperm which is capable for fertilisation as has acquired functional capacity

Question 21

Describe the first mitotic division during spermatogenesis

Answer 21

Spermatogonium to primary spermatocyte which has diploid chromosome number - 46

Question 22

Describe the first meiotic division during spermatogenesis

Answer 22

Primary spermatocyte to secondary spermatocyte - 2 cells with haploid chromosome number - 23

Question 23

Describe the second meiotic division during spermatogenesis

Answer 23

Secondary spermatocyte to spermatid, 2 cells with haploid chromosome number - 23

Question 24

What are the factors affecting spermatogenesis?

Answer 24

Medical, lifestyle or both can lead to male infertility

Question 25

What are the 2 types of medical factors affecting spermatogenesis?

Answer 25

Pretesticular - problem with the hormonal control Testicular - problem at the site of production

Question 26

What can cause pretesticular medical factors affecting spermatogenesis?

Answer 26

Functional - weight loss or gain Intracranial tumours, cysts or bleeds Prolactinoma Medications - opiates, external testosterone and steroids Genetic - Kallmann's syndrome

Question 27

What can cause testicular medical factors affecting spermatogenesis?

Answer 27

Surgery - orchidectomy and orchidopexy STI Mumps orchitis Testicular trauma or torsion RT or chemo Genetic - Klinefelter's and Y chromosome microdeletion

Question 28

What are some environmental/ lifestyle factors affecting spermatogenesis?

Answer 28

Traffic/ diesel exhaust Occupational and chemical exposures Sedentary position Reduced testosterone and increased oestradiol Obesity and smoking

Question 29

What are maternal factors affecting spermatogenesis?

Answer 29

Mother factors are irreversible Obesity, persistent organic pollutants, diesel, smoking, use of cosmetics

Question 30

What are some steps to recue the impact of factors affecting fertility?

Answer 30

Improve lifestyle - BMI, smoking, alcohol, diet, occupation Optimise underlying medical condition Stop medications Reduce STI risk Fertility preservation

Question 31

What is the normal sperm count?

Answer 31

More than 15 million/ ml Motility is more than 32% of sample

Question 32

What are clues for pretesticular causes affecting spermatogenesis?

Answer 32

Systemic illness, chemo, prolactinoma, Kallmann's, medication/ steroid use, extreme exercise and weight gain/ loss

Question 33

What are clues for testicular causes affecting spermatogenesis?

Answer 33

STI, testes trauma or torsion, surgery, varicocele and genetic

Question 34

What are clues for lifestyle affecting spermatogenesis?

Answer 34

Heat, smoking, BMI, excessive alcohol, recreational drug use, occupation exposure to chemical, heavy metal and radiation

Question 35

What are some investigations used for male infertility?

Answer 35

BMI, genetic exam, USS testes, hormonal profile and genetic test

Question 36

What can be seen in examination for male infertility?

Answer 36

High BMI Small testes, varicocele, surgical scar Absence of vas deferens in CF

Question 37

What can be seen in hormonal profile for male infertility?

Answer 37

Low FSH, LH, prolactin and testosterone from hypothalamus or pituitary cause - hypogonadotropic hypogonadism High prolactin Testicular cause - high FSH, LH but low testosterone

Question 38

What can genetic tests show in male infertility?

Answer 38

Abnormal karyotype, CF and microdeletion

Question 39

What can be shown on USS testes in male infertility?

Answer 39

Testicular volume, hydrocele, varicocele and cancer