Physiology - Basic Reproductive System (Male)

Question 1

What kind of cells are sperm cells produced from?

Answer 1

Primordial germ cells

Question 2

What is the length of the average spermatogenesis cycle?

Answer 2

64 days

Question 3

What are the 2 distinct phases in sperm development (spermatogenesis)?

Answer 3

• Spermatocytogenesis - Clonal expansion and maturation through mitotic and meiotic process
• Spermiogenesis - Differentiation into mature sperm cells

Question 4

What does the process of sperm production begin and end?

Answer 4

Process starts at puberty and continues lifelong

Question 5

What are the names used to describe the cells at each stage of production?

Answer 5

• Spermatogonia A
• Spermatogonia B
• Spermatocyte I
• Spermatocye II
• Spermatid
• Sperm

Question 6

What are the names used to describe the cells at each stage of production?

Answer 6

• Spermatogonia A
• Spermatogonia B
• Spermatocyte I
• Spermatocye II
• Spermatid
• Sperm

Question 7

How many mitotic divisions are there in sperm production?

Answer 7

1

Question 8

What occurs in the mitotic division stage?

Answer 8

Spermatogonium to primary spermatocyte-duplication, diploid chromosomes number

Question 9

How many meiotic divisions are there in sperm production?

Answer 9

2

Question 10

What occurs in the first meiotic division?

Answer 10

Primary spermatocyte to secondary spermatocyte, two cells with haploid chromosome number

Question 11

What occurs in the second meiotic division?

Answer 11

Secondary spermatocyte to spermatid, two cells with haploid chromosome number

Question 12

What is spermatogenesis?

Answer 12

Maturation of spermatids into functional sperm

Question 13

What factors can affect spermatogenesis?

Answer 13

• Medical
• Lifestyle
• Combination

Question 14

What are the 2 kinds of medical factors affecting spermatogenesis?

Answer 14

• Pretesticular - Problem with the hormonal control

* Testicular - Problem at the site of production

Question 15

What are pretesticular medical factors affecting spermatogenesis?

Answer 15

• Functional - excessive weight loss, gain
• Intracranial tumours, cysts, bleed
• Prolactinoma
• Medications - opiates, external testosterone, steroids (body building)
• Genetic - Kallmann’s syndrome

Question 16

What are testicular medical factors affecting spermatogenesis?

Answer 16

• Surgery - orchidectomy, orchidopexy
• STI
• Mumps orchitis
• Testicular trauma or torsion
• Radiotherapy or chemotherapy
• Genetic - Klinefelter’s (46 XXY), Y-chromosome microdeletion

Question 17

What are the lifestyle/environmental factors affecting spermatogenesis?

Answer 17

THESE ARE REVERSIBLE IN MEN
•Smoking
•Obesity
•Traffic/diesel exhaust
•Chemical exposure
•Sedentary position - heat exposure

Question 18

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

Answer 18

• Improve lifestyle- normal BMI, stop smoking, alcohol in recommended limits, healthy diet, exercise, adjustments to occupational exposure
• Optimise underlying medical condition
• Stop medications or switch to alternative pregnancy compatible medications
• Reduce STI risk and treat promptly if diagnosed.
• Fertility preservation - sperm freezing prior to surgery or cancer treatment

Question 19

What are the 3 types of cells present in the seminiferous tubules?

Answer 19

• Germ cells - produce sperm
• Sertoli/sustentacular cells - support sperm producing cell, PRODUCE INHIBIN
• Interstitial (Leydig) cells - produce testosterone

Question 20

What are the 2 main functions of the testes?

Answer 20

• Sperm production

* Testosterone production

Question 21

What is the role of testosterone?

Answer 21

• Male secondary sexual characters

* Controls spermatogenesis

Question 22

Which reproduction hormones are involved in the control of testicular function and where are they released from?

Answer 22

• GnRH - Gonadotrophin releasing hormone, produced from hypothalamus
• Gonadotrophins - FSH and LH, released from anterior pituitary
• Testosterone - released from testicles

Question 23

How do LH and FSH from the pituitary affect the testes?

Answer 23

They stimulate spermatogenesis and testosterone secretion by the testes
INTERACTION OF HORMONES

Question 24

What is the action of testosterone and inhibin on other hormones?

Answer 24

They inhibit the secretion of GnRH by th hypothalamus and LH & FSH by the pituitary

Question 25

What are some examinations/investigations used to assess male reproductive health?

Answer 25

* BMI * Genital examination - external genitalia, testicular size, palpation of vas deferens, inguinal hernia, varicocoele * USS testis * Hormonal profile - FSH, LH, Testosterone, Prolactin * Genetic test - Karyotype, Y-chromosome microdeletion

Question 26

What are some pretesticular causes of infertility?

Answer 26

* Systemic illness, local malignancy * Chemoradiotherapy, prolactinoma, Kallman’s(GnRH deficiency, genetic), * Steroid/testosterone/medication use * Extreme exercise, weight gain or loss (functional hypothalamic)

Question 27

What are some testicular causes of infertility?

Answer 27

* STI * Testes trauma or torsion * Surgery - orchidopexy, orchidectomy, inguinal hernia repair * Varicocoele * Genetic - Klinefelter, cystic fibrosis, Kartangener’s syndrome

Question 28

What are some lifestyle causes of infertility?

Answer 28

* Heat affecting testicles * Smoking * High BMI * Excessive alcohol * Recreational drug use * Occupation - exposure to chemicals/ heavy metal/radiation

Question 29

How may a clinical examination suggest male infertility?

Answer 29

* High BMI * Small testicles, varicocoele, surgical scar- testicular cause * Absence of vas deferens - cystic fibrosis

Question 30

How may a hormonal profile indicate male infertility?

Answer 30

* Low FSH, LH, Prolactin, testoserone- Hypothalamus or Pituitary cause (hypogonadotropic hypogonadism) * High Prolactin - Prolactinoma * High FSH, LH but low testosterone - Testicular cause (hypergonadotropic hypogonadism)

Question 31

How may a testes USS indicate male infertility?

Answer 31

* Testicular volume * Hydrocoele * Varicocoele * Cancer