11.11 Histology of the Male Reproductive System Flashcards
What surrounds the testes?
Does this layer simply surround the testes?
A thick layer of connective tissue called the tunica albuginea
The tunica albuginea has internal extensions that act like septa and run into the testes to divide it up into ~250 incomplete compartments
What structures lie in the compartments of the testes?
Within each space are seminiferous tubules that are curled up within spaces (usually 1-4 tubules) each of which is about 50 cm long
How do the many seminiferous tubules coalese into the single ductal structure of the male reproductive system?
Seminiferous tubules all drain into smaller ducts called the rete testis. These ducts then drain into efferent ductules to epididymis
Describe the epithelium of the seminiferous tubules
- Stratified epithelium
- Tunica (lamina) propria lacks fibroblasts but contains myoid cells (contractile smooth muscle like cells)
- Myoid cells are not true smooth muscle cells but capable of contraction forming a wall outside epithelium
- Tunica propria also contains Leydig cells (large steroid secreting cells)
What is the function of the seminiferous tubule?
- Stratified epithelium is site of spermatogenesis
- Spermatozoa in different stages of maturation gives the stratified appearance.
- Spermatogonia are stem cells that divide to produce spermatocytes that undergo meiosis and mature as sperm
- Sertoli cells are support cells for this process
- Extend the length of the epithelium to anchor the spermatozoa
- have arms that extend out to other developing spermatozoa
What is the significance of the contractile ability of the tunica propria (myoid cells)?
Tunica propria can contract to provide peristaltic movement of fluid containing sperm down seminiferous tubule.
This fluid comes from epithelium (sertoli cells mainly)
What is the major source of testosterone in the testis?
Leydig cells
These are active for first 5 months of fetal life and are then inactive until puberty
Describe the interchange between the seminiferous tubule and the rete testes
The final part of the seminiferous tubule is straight (tubuli recti) and lined with Sertoli cells only and finally simple cuboidal epithelium
The tubuli recti connect to the rete testis, an interconnected set of channels lined with ciliated cuboidal cells
What is the next step of the semen through the reproductive system after it has passaged through the rete testis
Rete Testis is the interchange where all seminiferous tubules join to collective ducts.
Then sperm is directed out the top of testes through efferent ductules (about 20 of them) into the epididymis lying on the flank of the testes
What two structures are derived from the mesonephric (Wolffian) duct?
(ie. the remnant duct of renal embryonic origin that has been repurposed)
Epididymis and ductus defferens
Around 20 surviving mesonephric tubules (efferent ductules) connect rete testis to single coiled ductus epididymis
Describe the structure of the epididymis
- Both the efferent ductules and epididymis are lined with ciliated pseudostratified columnar epithelium
- Epithelium surrounded by smooth muscle
- Epididymis is 4-6 m long and highly coiled
- Consists of head (connected to the ductules), body and tail (to the vas deferens)
What is the function of the epididymis?
- Maturation of sperm
- Includes decapacitation, the inhibition of the ability of the sperm to fertilise an egg (reversed in vagina). Inhibitory factors secreted by epididymis
- Enzyme system required for fertilisation are not required during transport (one shot system). Want to save this
- Capacitation (reversal) doesn’t occur until sperm enter the vagina
- Epididymis also absorbs most testicular fluid around sperm and clean up debris
Describe the path of the vas deferens (ductus deferens) from the testes to the prostate gland
Becomes known as the vas deferens once the coiling structure of the epididymis tube becomes straight.
- Runs into the abdomen via inguinal canal (as part of spermatic cord)
- Passes over the lip of the pelvis and descends to prostate at base of bladder
- Through the prostate it becomes known as the ejaculatory duct
- They join with the urethra within the prostate gland
Describe the structure of the wall of the vas deferens
- Irregular lumen shape
- Lined with ciliated pseudostratified columnar epithelium
-
Thick smooth muscle coat (except in ejaculatory duct)
- Critical for ejaculation by contraction of smooth muscle to get the system moving
Where are the seminal vesicles located?
On ductus deferens near the prostate (contribute to the vas deferens just before the entrance into the prostate gland)
Describe the structure and location of the prostate gland
- Largest accessory sex gland (“a walnut”)
- On anterior rectal wall, inferior to bladder
- On the base of the bladder where the urethra exits (built around the urethra)
- 30-50 tubuloalveolar glands opening into urethra and prostatic sinuses
- Packaged together in a connective tissue sheath all emptying into the urethra
Describe the histology of the prostate gland
- Lobular appearance divided by connective tissue
- Centrally located urethra (U)
- Inferior paired ejaculatory ducts (ED)
- Branching prostatic (urethral) sinuses
- Main prostatic glands (M) drain into urethra via long ducts (dotted line)
- Submucosal glands (SG) drain via prostatic sinuses
- Tiny mucosal glands open directly into urethra
In pathology, it is often useful to describe the prostate in terms of zones, especially for accessing the health of the urethra and gland.
What are the 4 zones of the prostate?
- Central zone – surrounds ejaculatory ducts
- Peripheral zone – surrounds central zone
- Transitional zone – surrounds prostatic urethra
- Periurethral zone – immediately adjacent to urethra
What kind of epithelium is in the prostate gland?
Epithelium is heterogenous (columnar or cuboidal, pseudostratified)
- Separated by connective tissue containing abundant smooth muscle - to aid in squeezing out contents
- Wall to wall glands (white space are lumens) which all eventually coalese to drain into the urethra
What are prostatic concentrations?
- Lumen of prostatic glands can contain prostatic concretions (more common with age)
- These are non-pathological accumulations of protein, calcium phosphate, cholesterol and cellular debris
- It occurs with normal aging - due to the ppt of salts etc involved in secretions
- Rarely cause issues
The penis becomes erect by a hydraulic mechanism (engorgment with blood flow).
What are the 3 structures that enable this to work?
Three separate masses of erectile tissue inflated with blood
- corpora cavernosa x2
- corpus spongiosum
Describe the location of the cavernous tissue
- The corpus spongiousm lies in the ventral most part of the penis. This is a mass of open vascular tissue surrounding the urethra.
- Dorsal to (often surrounding) the urethra are the two corpus cavernousa
Desribe penile histology
- Cavernous tissue contains many potential vascular spaces
- SINUSES that have potential to fill with blood
- Spaces surrounded by smooth muscle and connective tissue
- Smooth muscle are active and contracted squeezes shut so no blood flow through it but under right stmiuli, SMC relaxes and inflates erectile tissue with blood flow.
What is known about the anatomy of the clitoris?
External clitoris is the glans sitting at the head. The body runs backwards and a shaft to the pelvis and it splits. One branch on either side. (looks like cavernous tissue of the penis)
Erectile tissue that is unique: 2 masses of erectile tissue on the flanks of the vagina deep to the labia minor = buls of the clitoris). not attached to it but are separate
Describe the histology of the clitoris
Describe function
- Body of clitoris has bilateral cavernous tissue (= c. cavernosum?) surrounded by tunica albuginea
- Crus of clitoris extends inferiorly along pelvis
Function:
- Clitoral erection assumed to be same basis as penile erection
- Should be affected by same drugs
- Role of the bulbs of the clitoris uncertain, no male homologue
