Formation of male gametes

Question 1

How long does it take to make spermatozoa?

Answer 1

64-74 days

Question 2

What are Leydig cells?

Answer 2

Interstitial cells in the testes. They secrete androgens (testosterone) in response to LH

Question 3

What are sertoli cells?

Answer 3

columnar epithelium that make up the seminiferous tubules. They support spermatogenesis (blood testis barrier and bind androgrens) and suppress mullerian ducts during embryogenesis

Question 4

What is the function of sertoli cells?

Answer 4

They support spermatogenesis by protecting developing gametes from the blood (blood testis barrier), secreting androgen binding protein to bind testosterone, produce inhibin in response to androgens to suppress FSH, excreting the waste developing sperms and during 8th or 9th week of embryology they secrete anti-mullerian hormone to suppress female mullerian ducts

Question 5

What is the rete testis?

Answer 5

An anastomising network of seminiferous tubules - fluid is absorbed, sperm become concentrated

Question 6

What is the function of the epididymus?

Answer 6

Site of sperm maturation, storage prior to ejaculation, recycles damaged spermatozoa, adjusts and monitors fluid composition

Question 7

What is cryptoorchidism?

Answer 7

Undescended testis (the testes descend in the 7th month of life into the scrotum), if the testis does not descend then the temperature is too warm and the germ cells degenerate and die, never forming spermatozoa. The leydig cells will however continue to produce testoterone.

Question 8

What are spermatogonia?

Answer 8

Stem cells (or germ cells), diploid cells (type a and type b) - type b matures to form primary spermatocytes, divide by mitosis

Question 9

What is the difference between a primary and secondary spermatocyte?

Answer 9

Primary spermatocytes are mature spermatogonia, when the primary spermatocyte undergoes its first meiotic division (prophase lasts 22days) it is called a secondary spermatocyte

Question 10

What is a spermatid?

Answer 10

A haploid sperm cell formed from the second meiotic division of a secondary spermatocyte - spermatids go on to form spermatozoa

Question 11

Where does spermatogenesis occur?

Answer 11

In the seminiferous tubules

Question 12

Describe the stages of spermatogenesis

Answer 12

spermatogonia (diploid germ cells), undergo mitosis, mature to primary spermatocytes, which undergo meiosis 1 to form secondary spermatocytes, which undergo mitosis 2 to form spermatids (haploid cells) which mature into spermatozoa

Question 13

Normal speed of a spermatozoon

Answer 13

1-4mm/min

Question 14

Describe the stimulating hormones involved in spermatogenesis

Answer 14

GnRH released by the hypothalamus stimulates the anterior pituitary gland to release LH and FSH.
LH stimulates the leydig cells to form and secrete testosterone.
Testosterone is essential for growth and division of spermatogonia
FSH stimulates the sertoli cells to produce androgen binding receptors AND stimulates spermatogenesis causing the primary spermatocytes to undergo meiosis 1.

Question 15

Describe the negative feedback mechanisms involved in spermatogenesis

Answer 15

Inhibin released by the sertoli cells in response to androgrens has negative feedback on hypothalamus and anterior pituitary gland
Testosterone (produced by the leydig cells) also has a negative feedback on the hypothalamus and ant. pituitary gland

Question 16

Life expectancy of sperm in the female genital tract

Answer 16

Maximum 1-2days

Question 17

pH required for sperm to be mobile

Answer 17

Sperm a mobile in alkaline conditions (6-6.5)

Question 18

Normal pH of the vagina

Answer 18

3.5-4.0 (acidic)

Question 19

Describe the anatomy of male erectile tissue

Answer 19

Two corpus cavernosum, superior to the corpos spongiosum (singular), which carries the urethra

Question 20

What is the physiology of a male erection?

Answer 20

stimulation (physical/psychic) causes parasympathetic stimulation of the penis (S2-4 pelvic splanchnic nerve), resulting in increased arterial flow in the erectile tissue. The corpus cavernosa swell and the tunica albuginea surrounding prevent the blood from draining. The corpus spongiosum protects the urethra from being compressed during an erection

Question 21

What is the physiology of male ejaculation?

Answer 21

Sympathetic fibers (T11-L2- hypogastric and S2-S4 pudendal) stimulate emission- vas deferens contracts and sperm enter the urethra stimulating fluid secretion - feedback to spinal nerves s2-s4 in pudendal nerve to stimulate ejaculation (contraction of erectile tissue)

Question 22

Define androgen

Answer 22

Any hormone that has masculinising effects

Question 23

What are the precursors of androgens?

Answer 23

cholesterol or acetyl-coenzyme A

Question 24

What stages in life is testosterone produced in males?

Answer 24

During pregnancy (stimulated by HCG) at approx 7th week of life from genital ridge and later the testes, in the first 2 months after birth, from puberty (age 13), dropping after age 50

Question 25

When do the testes descend into the scrotum?

Answer 25

In the last 2-3 months of gestation -stimulated by testosterone

Question 26

How is testosterone converted to dihydrotestosterone?

Answer 26

5 alpha reductase enzyme

Question 27

What is the hyatid morgagni?

Answer 27

remnant of the mullerian duct

Question 28

In embryology, what is the process of male sex differentiation

Answer 28

Y chromosome has sex differentiating gene - causes sertoli and leydig cells to form in the gonads - leydig cells produce testosterone in response to HCG from the placenta and sertoli cells produce mullerian inhibiting factor which causes the mullerian tract (paramesonephric tract) to degenerate. The wolfian (mesonephric tracts) remain and form the epididymis, vas deferens and seminal vesicles, testosterone causes the formation of external male genitalia

Question 29

Which ducts in embryology form male reproductive organs?

Answer 29

wolffian or mesonephric ducts

Question 30

Which ducts in embryology form female reproductive organs?

Answer 30

mullerian or paramesonephric ducts

Question 31

What causes the mullerian duct to degenerate?

Answer 31

mullerian inhibiting factor produced by the sertoli cells

Question 32

What is the function of the gubernaculum?

Answer 32

To guide the gonads from the abdomen into the pelvis

Question 33

What do the remnants of the gubernaculum form in males?

Answer 33

Scrotal ligaments

Question 34

What do the remnants of the gubernaculum form in females?

Answer 34

round and ovarian ligaments

Question 35

What do the mullerian ducts form?

Answer 35

uterus, fallopian tubes, upper 1/3 of the vagina

Question 36

In embryology, what does the urogenital sinus form in males?

Answer 36

prostate/bulbourethral glands/urinary bladder

Question 37

In embryology, what does the urogenital sinus form in females?

Answer 37

lower 1/3 of the vagina, urinary bladder, urethra, urethral and paraurethral glands

Question 38

In embryology, what is the ureteric bud and what does in arise from?

Answer 38

In both males and females, it arises from the mesonephron (wolfian duct) and grows to forms the ureters, renal pelvis, collecting tubules, calices

Question 39

When does gonadal differentiation occur?

Answer 39

6-7weeks gestation

Question 40

What is the composition of the spermatozoa tail?

Answer 40

2 central axial filaments (beta fibres) and 9 peripheral axial filaments (alpha fibres)