Lecture 7 - Male reproduction

Question 1

the gonads are formed from the _______ _____ which are located in the ______ ______ _______ of the embryo

Answer 1

gonadal ridges, upper lumbar region

Question 2

the testis migrate through the ___________ into the ________

Answer 2

abdomen, scrotum

Question 3

what is the failure of testes to descend called?

Answer 3

cryptorchidism
- 3% of males, most common defect

Question 4

true or false, 100% of cryptorchid males are infertile

Answer 4

false

Question 5

cryptorchidism in humans results in:

Answer 5

arrested spermatogenesis, but does not effect endocrine function

Question 6

what causes the movement of the testes from the abdomen to the pelvis?

Answer 6

the growth of the embryo relative to the unchanged size of the gubernaculum

Question 7

true or false, the gubernaculum controls the decent of the testes into the scrotum

Answer 7

false, the gubernaculum only drags the testes down to the pelvis as the embryo grows. the decent into the testes is via a different process.

Question 8

true or false: some animals are permanently cryptorchid and are called monotremes

Answer 8

true, such as the elephant

Question 9

what is MRKH syndrome?

Answer 9

when the female gubernaculum equivalent stunts development of the mature uterus

Question 10

how can cryptorchidism be mimicked?

Answer 10

by warming the testis while in the scrotum 4-7ºC higher than currently

Question 11

how are the testis/scrotum cooled?

Answer 11

• high density of swear glands
• spermatic artery is in close proximity to venous blood vessels, which cool the oxygenated blood coming into the testis

Question 12

what is the perineal raphe?

Answer 12

marks the division of the testis

Question 13

does the perineal raphe physically separate the testicles?

Answer 13

no, it is just used as an identifier to see where the separation is
- line runs from anus to ventral penis

Question 14

what is the cremaster muscle?

Answer 14

muscle that lies under the skin of the scrotum and controls the location of the scrotum in relation to the body

Question 15

when does the cremaster muscle contract?

Answer 15

when it is cold, to draw testis closer to the body

Question 16

what is the tunica albuginea?

Answer 16

a tough fibrous sheath that internally covers each testicle

Question 17

each testicle is divided into ________ of which each contains the _______________ _______.

Answer 17

lobules, seminiferous tubules

Question 18

how many seminiferous tubules per testicle?
and how much length of tubule per testicle?

Answer 18

approximately 800
80cm long each
= 640m of ST per testicle

Question 19

the time taken for sperm to be produced from a germ cell is?

Answer 19

constant, the duration of spermatogenesis is fixed, for a given species and does not vary under normal conditions.

Question 20

how long does spermatogenesis take in humans?

Answer 20

64 days exactly, and a new cycle starts every 16 days

Question 21

what mechanism allows us to get a constant supply of sperm?

Answer 21

the spermatogenic wave -> like traffic at a red light. cars at the back must wait for cars at the front to go before they can

Question 22

describe the general structure of the epididymis

Answer 22

comma shaped organ
- muscular tube with a pseudostratified epithelial lining

Question 23

describe the function of the epididymis

Answer 23

• site of sperm maturation
• learn to swim and fertilise

Question 24

how long do sperm spend in the epididymis?

Answer 24

only about 12 days

Question 25

what are the three regions of the epididymis?

Answer 25

- head (caput) - body (corpus) - tail (caudal)

Question 26

describe the caput of the epididymis

Answer 26

receives sperm from the rete testis. - sperm here cannot swim or fertilise yet. - large number of stereocilia

Question 27

what are stereocilia?

Answer 27

cilia that do not move, but absorb fluid

Question 28

describe the corpus of the epididymis

Answer 28

the convolutions decrease the the fluid content decreases

Question 29

describe the caudal of the epididymis

Answer 29

- less stereocilia - muscularity increased, and moving to three layers (as fluid reduces, more muscle is required to move sperm)

Question 30

what is the degree of concentration increase of sperm by fluid reabsorption in the epididymis?

Answer 30

100 fold increase in concentration

Question 31

describe the structure of the vans deferens

Answer 31

45cm long and have three muscular layers - inner longitudinal layer - middle circular layer - outer longitudinal layer

Question 32

what is the function of the vans deferens?

Answer 32

sperm storage, but must be able to move sperm well also

Question 33

describe the differences in the vas deferens at the epididymis end in comparison to the prostate end

Answer 33

the lumen is simple at the epididymal end, and at the prostate end it becomes enlarged and folded with many crypts, which allows for additional storage

Question 34

what is the name for the prostate end of the vas deferens that is large, folded and contains crypts for extra storage?

Answer 34

the ampulla

Question 35

what is the condition called where there is no vans deferens?

Answer 35

congenital absence of the vas deferens

Question 36

what are the features of CAVD?

Answer 36

- 95% of men with cystic fibrosis have it, but also happens in normal men - usually bilateral, both vas are missing - due to genetic mutations probably - patients are usually infertile

Question 37

can a man do no nut november?

Answer 37

yes, their excess sperm is lost in the urine - those bloody men are liars