Male Reproductive System Flashcards
3 functions of male reproductive system
1 - production of spermatazoa
2 - delivery of semen into the female reproductive tract
3 - production of androgens, chiefly testosterone
What are the 3 layers of the scrotum lining?
Mesothelium
Tunica Albuginea
Tunica Vasculosa
What is the function of the tunica albuginea in the testis?
Tough fibrous capsule
What is the function of the tunica vasculosa in the testis?
Sends septa into the testis to divide it into lobules
Excretory tubules of the testes
Seminiferous tubules connected to the rete testis by straight tubules.
Rete testis carry sperm out of the testis connecting to a series of efferent ductules forming the head of the epididymis
Body and tail of epididymis forms a single coiled tube where sperm mature and are temporarily stored.
Epididymis continuous with vas deferens which takes sperm away from scrotum and along spermatic cord during ejaculation.
What are seminiferous tubules lined by?
Seminiferous epithelium consisting of various germ cells and a support cell called a Sertoli cell
What is seminiferous epithelium bound by?
A basal lamina and lamina propria of connective tissue and myofibroblasts.
What are leydig cells and where are they found?
Found in connective tissue between seminiferous tubules.
Endocrine cells which produce testosterone
What is spermatogenesis?
The process of proliferation and maturation that transforms diploid spermatagonia into haploid spermatazoa.
What is the journey of spermatagonia to spermatazoa during spermataogenesis?
Spermatagonia (mitosis) Primary Spermatocytes (meiosis 1 - slow process) Secondary spermatocytes (meiosis 2 - rapid process) Spermatids (spermiogenesis) Spermatozoa
What is the structure of sertoli cells?
They extend from the basal lamina to the lumen of their tubule.
Their cytoplasm ramifies and surrounds all of the developing cells.
5 functions of sertoli cells
1 - secrete factors that regulate spermatogenesis and spermiogenesis
2 - secrete factors that control Leydig cells
3 - secrete tubular fluid
4 - phagocytose discarded spermatid cytoplasm
5 - divide the tubule epithelium into two compartments via tight junctions
What does the basal compartment contain?
spermatagonia and early primary spermatocytes
What does the adluminal compartment contain?
All other developing cells (not spermatagonia or primary spermatocytes)
What is spermiogenesis?
The maturation of the spermatid into a spermatozoa
Key steps of spermiogenesis
1 - production of acrosomal cap from acrosomal vesicle. Has enzymes that allow penetration of corona radiata and zona pellucida during fertilisation.
2 - elongation of nucleus and centriole to form flagellum
3 - release of excess cytoplasm (residual body) which is phagocytosed by sertoli cell
What is spermiation?
Release of the spermatazoa by sertoli cells into the lumen
How do spermatozoa get to the rete testis and epididymis?
Because they are immotile and incapable of fertilisation at spermiation, they are swept into the rete testis and epididymis by fluid flow and peristalsis.
They become fertile and motile during their passage through the epididymis.
What do Leydig cells respond to?
LH from the pituitary gland releasing testosterone which acts locally on seminiferous tubules and enters circulation
What are the rete testis lined by?
Simple cuboidal ciliated epithelium
What are the efferent ducts lined by?
Ciliated epithelium that varies from cuboidal to pseudostratified columnar - gives surface of tubules a “scalloped” appearance
What happens in the efferent ducts?
Most of the fluid that comes from the testis is absorbed here
What is the epididymis lined by?
Pseudostratified columnar epithelium with stereocilia
What happens in the epididymis?
Sperm are stored for about a week and mature, becoming motile and capable of fertilisation
What are the vas deferens lined by?
Pseudostratified columnar epithelium with stereocilia
What happens in the vas deferens?
3 layers of smooth muscle innervated by sympathetic nervous system producing strong peristalsis during ejaculation
What is most of the ejaculate derived from?
Seminal vesicles and prostate gland
What do the bulbourethral glands contribute?
A clear fluid that is released before ejaculation which helps lubricate the urethra.
What are the 3 segments of the urethra?
Prostatic urethra
Membranous urethra
Penile urethra
What are the seminal vesicles?
A sac with a complex array of folds lined by pseudostratified columnar epithelium with smooth muscle surrounding the folds
What does the duct from the seminal vesicle join and then form?
Joins the vas deferens to form the ejaculatory duct which pierces the prostate gland and empties into the urethra
Structure of the prostate
Surrounded by a thin fibromuscular capsule and defined by fibromuscular septa forming spaces lined by heterogeneous secretory epithelium.
What passes through the prostate and where?
Urethra and ejaculatory ducts pass through fibrous stromal tissue at the centre of the gland
What does the prostate gland produce?
A watery fluid that makes up about a third of the ejaculate
What are the three zones of the prostate?
Transitional zone - around urethra
Central zone - posterior to transitional zone
Peripheral zone - lateral to other zones, makes up most of gland
What is the structure of the penis?
Richly vascularised subcutaneous layer Fibrocollagenous capsule (tunica albuginea) containing 3 erectile columns - 2 corpora cavernosa and corpus spongiosum which has urethra running through
Why does the spongiosum have less erectile function than the cavernosa?
Contains more connective tissue which aids passage of semen through the urethra
What is the penile urethra lined by?
Stratified columnar epithelium, changing to non-keratinised stratified squamous near the tip
Structure of erectile tissue
Consists of blood sinuses surrounded by fibromuscular tissue containing smooth muscle
What are the blood sinuses in erectile tissue supplied by?
Helicine arteries which are spiral in shape
What does parasympathetic stimulation of the penis lead to?
Dilation of the helicine arteries which causes the sinuses to become engorged with blood and press on the veins, restricting venous outflow
