Male Reproductive System Flashcards
What does the male reproductive system include?
- testis,
- epididymis,
- ductus deferens,
- accessory glands.
What is the major function of the male reproductive system?
produce semen, consisting of:
- spermatozoa
- androgens (testosterone (male sex hormones))
- facilitate the fertilization process (introduce spermatozoa into the female genital tract)
Where are the testis located?
contained in the scrotum
What is semen made up of?
- spermatozoa cells
- associated secretions
State the histological composition of testis.
- compound tubular glands
- thick tunica albuginea capsule of dense irregular connective tissue
- tunica vaginalis visceral layer covering of the tunica albuginea
What 2 tunics are present in the testis? What are their locations?
- tunica albuginea (the capsule)
- tunica vaginalis (visceral covering of the tunica albuginea)
What type of glands do the testis contain?
compound tubular glands
What is the tunica albuginea made of? Why is it special?
- dense irregular connective tissue (capsule)
- much thicker than usual ‘capsule’
- ‘albuginea’ refers to ‘alba’ the while layer (extra thick)
- branches projecting deeper into the parenchymal organ, dividing it into lobules.
What is a special feature connecting the tunica albuginea with the parenchymal organ? What does this lead to?
- septa of connective tissue
- branches extending from the tunica albuginea
- partially/completely divide the organ up into lobules
- 200-300 individual lobules (“lobuli testis”)
What is present within each of the testicular lobules? What is their main function?
semineferous tubules: associated with sperm cell production
What are semineferous tubules lined with?
complex stratified germinal epithelium:
- spermatogenic cells
- sertoli cells
What do spermatogenic cells give rise to?
spermatozoa
What process occurs within the semineferous tubules?
spermatogenesis
What 2 distinct cell populations does the stratified epithelium of semineferous tubules contain? (Function?)
- spermatogenic cells (directly associated with the development process of sperm cells)
- sertoli cells (helper cells for spermatogonia (sperm cell) development)
Which part of the semineferous tubule contains the most primitive cell type?
deepest layer, adjacent to the basal lamina
least developed cells
What are the different names for sperm cells as they develop?
spermatogonial stem cell
spermatogonium
primary spermatocyte
secondary spermatocyte
early spermatid
sperm
Explain the development of the sperm cell.
primordial germ cell
mitotic divisions
spermatogonial stem cell (2n)
mitotic divisions
primary spermatocyte (2n)
meiosis I
2 secondary spermatocyte (n)
meiosis II
4 early spermatid (n)
differentiation
4 sperm (n)
What is the location of the most advanced and structurally developed cells?
lumen of the semineferous tubule (towards the center)
Which cells are present in fewer number in the testis?
sertoli cells (sustentacular cells)
How do Sertoli cells look?
Nucleus:
- pale
- oval/triangular
- prominent
- occasional cleft-like infoldings
Cell:
- tall
- extend from the basement membrane to the lumen of the tubule
- boundries are indistinct in histological preperations
- lateral and apical invaginations in the cell membrane (ebrace the differenciating spermatogenic cells)
What part of the Sertoli cell embraces the differentiating spermatogenic cell?
the numerous lateral and apical invaginations of the cell membranes
What is the function of Sertoli cells?
provide:
- nutritional requirements (from surrounding rich capillary network)
- enzymes
- growth factors
- hormones (accumulate testosterone, but don’t produce it)
can consume unneeded spermatozoa cells
form the blood-testis barrier which seperates tubules from capillaries by forming tight junctions. cause spermatogenic cells to be sealed off in a protective compartment (isolate cells from blood, ensuring immune system cells do not recognise them and launch an immune response)
Where are Leydig cells found? Another name?
Leydig cells = interstitial cells
- found near semineferoud tubules (between the tubes)
What cells create the blood-testis barrier?
sertoli cells
What is the function of leydig cells?
produce testosterone
How do Leydig cells look?
- round/polyhedral
- large nucleus
little distinguishing features; easy distinguishing due to location
What produces testosterone?
Leydig cells
What happens to the number of spermatogenic and sertoli cells near the terminal segment of a
seminiferous tubule?
- spermatogenic cells decrease
- sertoli cells increase
What is the transitional zone? What is it lined by?
- zone joining a seminiferous tubule to a
straight tubule - lined by sertoli cells
State the histological composition of the straight tubule.
- lined by simple columnar / cuboidal / squamous cells
- continuous with a network of
anastomosing channels that form the rete testis.
State the histological composition of the rete testis.
- simple squamous / cuboidal epithelium
- can be bistratied
cuboidal in the bull. - surrounded by the loose
connective tissue of the
mediastinum testis.
What is an oversimplification which explains what happens to the epithelium layers as they pass through all the compartments?
gradually decrease
What are efferent ductules lined by?
simple columnar/ pseudostratified
epithelium
+ ciliated cells
What is the location of efferent ductules?
lead from: rete testis
pass through: tunica albuginea
join: epididymis duct
When does the difference occur in the epithelium linings?
efferent ductules!
usually pseudostratified epithelium!
What is the duct of the epididymis?
- single, narrow, slightly-coiled tube
- eq: 70m
- bull: 40m
- human: 6m
- structure varies depending on the region.
What is the histological composition of the epididymis duct?
- pseudostratfied columnar epithelium,
- tall columnar lining cells (princuipal cells)
- contains stereocilia (microvilia)
- basal cells (renew the principal cell population)
- layer of circular smooth muscle (contraction: movement of sperm from the head to the tail)
- lumen: filled with spermatozoa cells (undergoing the final maturation step)
What muscle enables the movement of sperm? What direction?
- dunctus of epididymis
- circular smooth muscle cells
- duct head to the duct tail
Where is the epididymis thickest/thinnest?
- thickest: head region
- thinnest: tail region
What is the location of the vas deferens? Different name?
vas deferens = ductus deferens
- duct of the epididymis –> urethra
What cells are present in all epitheliums?
basal cells: regenerate the principal cell population
State the histological composition of the vad deferens.
- lined by pseudostratified columnar epithelium
- some cells with stereocilia (become simple columnar distally)
folded lamina propria:
- allows the duct to expand during ejaculation
smooth muscle tissue:
- minor 2 layers: inner circular and outer longitudinal
- major 3 layers: inner & outer longitudinal and middle circular layer
- contracts upon sympatic nervous system stimulation
- outer layer – adventitia/serosa
What are the 2 parts of the penis?
- body
- glans penis
What do both of the penis regions contain?
- penile urethra
- erectile tissue
What 3 major bodies does the penic contain?
2 corpus caverosus (additional masses of erectile tissue)
1 corpus spongiosum (+urethra in the center)
What is the corpus spongiosum also known as?
corpus cavernosum of the urethra (as opposed to the corpus cavernosum of the penis)
What is each corpus cavernosum enclosed by?
- tunica albuginia (dense regular connective tissue)
- elastic fibers
not covered entirely! covered individually!
Explain the composition of the penis tunic.
- rum & su: thick
- eq: + smooth muscle
- extends inward forming a network of trabeculae (b/w spongy erectile tissue)
contains cavernous spaces:
- lined by endothelium (spaces may be filled with blood)
- surrounded by various
proportions of smooth muscle
- recieve blood supply
Where do cavernous spaces recieve their blood supply from?
groups of helicine arteries
What is teh best developed part of the penis in dogs and horses? What does it contain?
- glans penis (expanded, distal part of the penis)
- contains erectile tissue (continuous with corpus sponguosum)
What does the urethra carry?
both urine and semen
What are the two parts of the urethra?
- pelvic urethra
- penile urethra
State the composition of the pelvic urethra.
- lined by transitional epithelium
- may become stratified columnar / cuboidal distally.
State the composition of the penile urethra. Where is it located?
- location: ventral region of the penis,
lined by a mixture of transitional, stratified cuboidal, stratified columnar, or simple columnar epithelium.
What do male accessory glands include?
- glands of the ampulla,
- seminal vesicles,
- the bulbourethral glands,
- prostate gland.
What are male accessory glands composed of? Histological structure?
- tubular or tubuloacinar secretory units
- often have vesicular dilations
- pseudostratified secretory epithelium
What does the vas deferens form near its junction with the urethea?
ampulla
What is the lamina propria and submucosa of teh ampulla filled with?
glandular secretory units
Where is the ampulla absent? Where is it nor well developed?
absent: cat
not well developed: su
State the species differences of seminal vesicles? Different name?
car: absent
eq: true vesicular outpocketings in the form of
bladderlike sacs with wide central lumens into which the glands open
su, rum: compact glands with a lobulated surface
seminal vesicles = vesicular glands
State the histological composition of seminal vesicles.
vesicles consist of:
- outer layer of connective tissue
- layer of smooth muscles
lumen:
- lines by psudostratified epithelium
- highly folded (giving a honeycomb appearance)
What is a major distinctive feature of the prostate gland?
honeycomb appearance
Where are bulbourethral glands present? Other name? What do they secrete?
- secrete mucous
- bulbourethral glands = cowper’s glands
- all domestic animals exept dogs!
State the histological composition of bulbourethral glands.
- columnar pseudostratified epithelium
- tall cells
- pale cells
- possess basally displaced nuclei
What is a distinctive feature of bulbourethral glands?
- large cells
- tall cell
- pale cells
Where does the bulbourethral gland secrete its secrete? When? What is the function?
- where: amnial urethra
- time: just before ejaculation
- function: lubricate the urethra.
What type of gland is the prostate gland?
seromucous gland - exception dog: entirely serous.
State the histological composition of the prostate gland.
- partially/completely surrounds the pelvic urethra
- encapsulated
- large trabeculae (from the capsule)
- lobulated (around 50 glands)
secretory tubules, alveoli, and intraglandular ducts:
- lined by a simple cuboidal/columnar or pseudostratified epithelium
- occasional basal cells.
-
simple epithelium –> stratified columnar / transitional
epithelium (duct terminal portions)
What is the major source of energy for spermatozoa cells? Where is most of it located?
fructose!
present in viscous fluid (secreted by seminal vesicles)
How rich is the seminal fluid in the fructose secrete?
can reach up to 85% of the total fluid
What is the largest, most important male accessory gland?
prostate gland
What is a distinctive feature of the protate gland?
- highly folded inner surface and end parts
- muscle cells present in stroma (around gland end part)
- secretory unita are surrounded by fibro-muscular stroma (fibro-connetive tissue, muscular-muscle) which contracts to enable ejaculation
