The male reproductive system Flashcards
What are the different parts of the urethra
- Prostatic urethra
- Membranous urethra
- Spongy urethra (penile)
What does the spongy urethra go through
Corpus spongiosum
Function of testes
Production and temporary storage of sperm
Synthesis and secretion of: testosterone, oestrogen, action, inhibin, oxytocin
What are the layers of the testes
Skin
Dartos muscle
Tunica vaginalis
What is the role of the tunica albuginea
Splits testes into fibrous lobules (each of which contain 1-4 coiled seminiferous tubules)
What are the 2 compartments in the seminiferous tubules
Tubular and extra-tubular (endocrine)
Where do Leydig cells lie
In interstitial spaces between seminiferous tubules
What receptors are on Leydig cells and what does this do
LH receptors, LH stimulation leads to synthesis of testosterone and oxytocin which enter tubules and neighbouring blood vessels
What do Sertoli cells do
Have cytoplasmic extensions which help form a meshwork with tight junctions between adjacenct cells. This is the Blood-testis Barrier. Tight junctions form a fence between the basal and adlumenal spaces
What reside in the basal compartment
Stem cells of spermatogonia
What happens in the adlumenal compartment
Upon release of spermatogonium, spermatocytes underrates undergo spermatogenesis
What happens in luminal compartment
Spermatids are found on luminal surface. Fully formed Spermatozoa are found in lumen of seminiferous tubules
What is movement like in tight junctions
Only unidirectional movement of germ cells are allowed through the tight junctions. Tight junctions are open transiently and allow spermatogonia to enter the adlumenal compartment. Spermatozoa or spermatocytes cannot leak back out to basal compartment
What else do Sertoli cells do
Actively secrete molecules and nutrients into the adlumenal compartment for developing sperm
What is spermiogenesis
Packaging of chromosomes for effective delivery to the oocyte. Formation of head, neck and tail, loss of cytoplasm
Process of spermatogenesis
1) formation of acrosome close to nucleus. Has enzymes needed for fertilisation and also creates polarity of cell
2) Nuclear elongation. Anterior pole has acrosome, posterior pole has developing flagella to make tail
3) cytoplasm migrates to posterior part of cell, Excess cytoplasm pinched off so head contains nucleus only
4) mitochondria in neck
How is spermatogenesis stimulated
High levels of testosterone needed
- LH stimulates Leydig cells to produce testosterone which binds to receptors on Sertolili cells
- Testosterone induces receptors for FSH on Sertoli cells
- FSH from pituitary now stimulates Sertoli cells to produce androgen binding protein which binds and carries testosterone in testicular fluid to the entire ductal system
0 Sertoli cells also produce inhibin which is part of a negative feedback loop. It inhibits FSH production by pituitary gland
In absence of FSH, and LH spermatogenesis does not occur
What are rete testis
Network of channels into which fluid and spermatozoa form seminiferous tubules empty
What are rete testes lined with
Simple cuboidal or low columnar epithelial cells
What is the epithelium in the epididymis
Tall columnar epithelium with asymmetric modified microvilli, Important for absorption.
Function of epididymis
Absorption of fluid which concentrates sperm and phagocytosis
Secretion of glycoproteins, silica acid, defensin, glycerolphosphocholine (for maturation of spermatozoa)
Whatveins surround testicular artery
Pampiniform plexus. important for lymph drainage.
Protects vas deferens from overheating by being good at heat exchange
Layers of vas deferens
3 muscle layers. A fibre-elastic lamina propria and inner epithelium
What is vasectomy
Ligation of vas deferens. Does not cause fluid accumulation. Sperm build up and are removed by phagocytosis
