Lecture 7 - Male reproduction Flashcards
the gonads are formed from the _______ _____ which are located in the ______ ______ _______ of the embryo
gonadal ridges, upper lumbar region
the testis migrate through the ___________ into the ________
abdomen, scrotum
what is the failure of testes to descend called?
cryptorchidism
- 3% of males, most common defect
true or false, 100% of cryptorchid males are infertile
false
cryptorchidism in humans results in:
arrested spermatogenesis, but does not effect endocrine function
what structure is responsible for ensuring the descent of the testes?
gubernaculum
how does the gubernaculum drag the testis into the scrotum?
as the embryo and the testis grow, the gubernaculum does not, and this drags the testis down to the pelvis
true or false: some animals are permanently cryptorchid and are called monotremes
true, such as the elephant
what is MRKH syndrome?
when the female gubernaculum equivalent stunts development of the mature uterus
how can cryptorchidism be mimicked?
by warming the testis while in the scrotum 4-7ºC higher than currently
how are the testis/scrotum cooled?
- high density of swear glands
- spermatic artery is in close proximity to venous blood vessels, which cool the oxygenated blood coming into the testis
what is the perineal raphe?
marks the division of the testis
does the perineal raphe physically separate the testicles?
no, it is just used as an identifier to see where the separation is
- line runs from anus to ventral penis
what is the cremaster muscle?
muscle that lies under the skin of the scrotum and controls the location of the scrotum in relation to the body
when does the cremaster muscle contract?
when it is cold, to draw testis closer to the body
what is the tunica albuginea?
a tough fibrous sheath that internally covers each testicle
each testicle is divided into ________ of which each contains the _______________ _______.
lobules, seminiferous tubules
how many seminiferous tubules per testicle?
and how much length of tubule per testicle?
approximately 800
80cm long each
= 640m of ST per testicle
the time taken for sperm to be produced from a germ cell is?
constant, the duration of spermatogenesis is fixed, for a given species and does not vary under normal conditions.
how long does spermatogenesis take in humans?
64 days exactly, and a new cycle starts every 16 days
what mechanism allows us to get a constant supply of sperm?
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
describe the general structure of the epididymis
comma shaped organ
- muscular tube with a pseudostratified epithelial lining
describe the function of the epididymis
- site of sperm maturation
- learn to swim and fertilise
how long do sperm spend in the epididymis?
only about 12 days
what are the three regions of the epididymis?
- head (caput)
- body (corpus)
- tail (caudal)
describe the caput of the epididymis
receives sperm from the rete testis.
- sperm here cannot swim or fertilise yet.
- large number of stereocilia
what are stereocilia?
cilia that do not move, but absorb fluid
describe the corpus of the epididymis
the convolutions decrease the the fluid content decreases
describe the caudal of the epididymis
- less stereocilia
- muscularity increased, and moving to three layers (as fluid reduces, more muscle is required to move sperm)
what is the degree of concentration increase of sperm by fluid reabsorption in the epididymis?
100 fold increase in concentration
describe the structure of the vans deferens
45cm long and have three muscular layers
- inner longitudinal layer
- middle circular layer
- outer longitudinal layer
what is the function of the vans deferens?
sperm storage, but must be able to move sperm well also
describe the differences in the vas deferens at the epididymis end in comparison to the prostate end
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
what is the name for the prostate end of the vas deferens that is large, folded and contains crypts for extra storage?
the ampulla
what is the condition called where there is no vans deferens?
congenital absence of the vas deferens
what are the features of CAVD?
- 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
can a man do no nut november?
yes, their excess sperm is lost in the urine
- those bloody men are liars
