Male Infertility Flashcards
What determines sex of an individual?
the X and Y chromosomes - the Y chromosome will have the sex determining region
What effect does the Y chromosome have?
Y chromosome will cause development of the testis from the bipotential gland. The foetal testis will secrete testosterone and Mullerian Inhibiting Factor which will support the development of the Wollfian tract and the degradation of the Mullerian reproductive tract
Which tracts are developed in males and females?
Males - wollfian
Females - mullerian
What happens in the absence of the Y chromosome?
There is a lack of stimulus from testicular hormones (testosterone and mullerian inhibiting factor) so will develop internal female genital tract
Dihydrotestosterone will cause what?
presence and absence
The development of the genital tubercle and genital swelling (presence)
Regression of the genital tubercle to form the clitoris (absence)
When will external genitalia start to differentiate and when can it be seen on scan?
from 9 weeks
seen on scan at 16 weeks
What is the difference in function of testosterone and dihydrotestosterone?
Testosterone - produced by the testis and will cause increased expression of the Wolffian duct system (internal genitalia)
Dihydrotestosterone (converted from testosterone) will affect the external genitalia development
What is androgen insensitivity syndrome?
This is an X-linked disorder where the patient is phenotypically male (46XY) but there is insensitivity to androgens (testosterone).
What does androgen insensitivity syndrome cause?
As there is genetic insensitivity to androgen there will be no maturation of the Wolffian tract and the testis will not descend. Will also be phenotypically female as no dihydrotestosterone sensitivity to develop external genitalia.
There will be inhibition of the Mullerian ducts though so no ovaries or uterus.
How will androgen insensitivity syndrome tend to present?
Around puberty - will have primary amenorrhoea and lack of pubic hair
Vagina will be short, no ovaries or uterus
What forms the spermatic cord?
Vas deferens, pampiniform plexus, lymphatics and testicular artery
In which muscle bulk of the penis is the urethra located?
Corpus Spongiosum
What are the 3 muscle bulks in the penis?
Corpus spongiosum and 2 corpus cavernosum
Why is it important that the testis descend?
When does this happen?
there is a more ideal temperature in the scrotal sac for spermatogenesis (if delayed descent then can have impaired spermatogenesis and fertility problems) Before birth (androgen dependent)
What can be done in the scrotal sac to keep the testis at the optimum temperature?
contraction of the dartos muscle to raise and lower testis - this is a reflex
What is cryptorchidism?
This is when a person reaches adulthood but their testes have failed to descend.
What are the complications of cryptorchidism?
This is becoming increasingly common, it can cause infertility (although if unilateral then usually fertile), can increase risk of testicular germ cell cancer
What should be done to decrease risk of testicular germ cell cancer?
Orchidopexy - surgical movement of a testicle into the sac if <14 years old
If adult then consider and orchidectomy to remove undescended testicle.
What are the functions of the testis and where do these occur?
Spermatogenesis = seminiferous tubules (extension of the epididymis) around sertoli cells
Production of testosterone = leydig cells
What is the acrosome?
This is a covering on the head of the sperm that contains enzymes for penetrating the ovum surface
Discuss the roles of Sertoli cells
These are cells that are dedicated to supporting spermatogenesis and have many functions:
- Form a blood-testes barrier to protect cells from antibody attack
- provide nutrients to growing cells
- secrete seminiferous fluid to aid transport to the epididymis
- secretes androgen binding globulin to bind testosterone and ensure high concentration of testosterone (required for development)
- secretes inhibin and actin hormones to regulate spermatogenesis and FSH secretion
- phagocytoses cytoplasm excess and defective cells
What do FSH and LH stimulate in the male?
FSH = sertoli cells and spermatogenesis LH = leydig cells and production of testosterone
What will decrease secretion of LH and FSH?
LH is decreased by testosterone concentrations feeding back and suppressing GnRH release from hypothalamus and directly suppresses LH release from pituitary
FSH is decreased by inhibin hormone and increased by activin (released by sertoli cells)
What is GnRH?
Gonadotrophin releasing hormone is a decapeptide that is released from the hypothalamus in bursts every 2-3 hours starting from the age of about 8-12 years and continuing through adulthood