Histology of the Male reproductive system Flashcards
what does sperm and androgen production in the male repro tract?
Testes
what does sperm transport in the male repro tract?
Epididymis
Ductus deferens
Ejaculatory duct
Urethra
What does semen production and sperm nutrient source in the male repro tract?
Seminal vesicle
Prostate gland
Bulbourethral glands
what does copulatory organ with erectile tract in the male repro tract?
Penis
Characteristics and components of the testes?
Paired organs located in the scrotum, posteriorly associated with the epididymis
Dense CT capsule, the tunica albuginea that thickens posteriorly to form the mediastinum testis
also contains the tunica vaginalis which is derived from the peritoneum
- outer parietal layer lining the scrotum
- inner visceral layer covering the tunica albuginea
Characteristics and cell types of the seminiferous tubules
Septa creae 250-300 lobules containing 1-4 convoluted seminiferous tubules lined with seminiferous epithelium
- Sertoli cells
- Spermatogenic cells
Tubules surrounded by CT and 3-5 layers of peritubular myoid cells (help with contraction)
Interstitial cells of leydig found in between seminiferous tubules
Characteristics of Intersitial cells of Leydig
Present in between tubules close to blood vessels and lymphatic channels
Steroid producing cells containing lipid droplets, mitochondria, and a well developed sER
-Testosterone
Accompanied by myoid cells and fibroblasts
what two cells make up the Seminiferous epithelium and what are their characteristics
Sertoli cells:
- columnar cells with extensive processes that surround spermatogenic cells and occupy the spaces between them
- organize tubules and extend full thickness of epithelium
- cyclops nucleus
Spermatogenic cells:
- replicate and differentiate into mature sperm
- spermatogonia (most immature) rest on basal lamina
- spermatids (most mature) are attached to apical portion of sertoli cell, near tubule lumen
What is the function of the sertoli cells and how do they communicate?
Nurse cells with crypts supporting 30-50 germ cells
Function in:
- exchange/transport of metabolites and nutritive factors into lumen
- exocrine and endocrine secretion
- phagocytose residual bodies and effete spermatogenic cells
Bound by tight junctions to form the sertoli cell to sertoli cell junctional complex and establishes the blood-testis-barrier
two types of spermatogonia?
Spermatogonia: clonally divide (mitosis) located near the base ment membrane
Type A spermatogonia: generate copies of itsself and or differentiates into type B spermatogonia
Type B spermatogonia enter the meiotic prophase as primary spermatocytes
What are spermatocytes
Two meiotic divisions and inside blood testes barrier
primary spermatocytes go to secondary spermatocytes and then finally to spermatids as they move towards the lumen of the seminiferous tubule
what are the seminiferous compartments ad how do the sepermatocytes move throughout?
Sertoli-sertoli junctional complex divides epithelium into the basal and ad(luminal) compartments
- basal is below the blood testes barrier
- adluminal is above the blood testes barrer
Spermatogonia and early primary spermatocytes are restricted to basal compartmetn
Mature spermatocytes and spermatids are restricted to the adluminal side
Early spermatocytes must pass through junctional complex and move from basal to the adluminal compartment
complexes establish the blood testes barrier to help isolate the haploid cells from systematic circulation
- secondary spermatocytes
- spermatids
- sperm
process of spermatogenesis in the seminiferous tubules and when is the spermatid released from the seminiferous tubules?
Spermatids undergo spermatogenesis
- Round spermatids (early) are housed in niches of sertoli cells
- elongated (late) spermatids: housed in apical crypts of sertoli cells
Mature spermatids are released via spermiation:
- intercellular bridges leave residual bodies and lost and mature spermatids are lost
- spermatozoa are fully formed but not yet functional
- sperm are released into lumen and propelled to the epididymal duct
Structure of the sperm
Mature sperm are comprised of a head, neck, and tail
Head contains a flattened and elongated nucleus
-partially capped by the acrosome which contains hydrolytic enzymes
Tail is subdivided into 3 pieces:
- Middle piece, containing mitochondria
- principle piece: longest segment
- end piece
What is the sperm transport pathway?
Straight tubules Rete testis Efferent ductules Epididymis ductus deferens Ejaculatory duct
Location, epithelium, support tissues and function: Seminiferous vesicle
Location: Testicular lobules
Epithelium: Spermatogenic, with setoli cells and germ cells
Support tissues: myoid cells and loose CT
Function: Produce sperm
Location, epithelium, support tissues and function: Straight tubules
LOcation:
-Periphery of the mediastinum testis
Epithelium:
- proximal= sertoli cells only
- distal = simple cuboidal
Support tissues:
-Connective tissue
Function:
-Convey sperm into rete testis
Location, epithelium, support tissues and function: Rete testis
Location:
-In mediastinum testis
Epithelium: Simple cuboidal with microvilla and single cilla
Support tissues:
-Dense irregular CT, highly vascular
Functions:
-Collects sperm from seminiferous tubules
Location, epithelium, support tissues and function: Efferent ductules
Location: From rete testis to the head of the epididymis
Epithelium: Alternating patches of simple, cuboidal nonciliated and simple columnar ciliated
support tissues:
-thin circular layer of smooth muscle and vascular loose CT tissue
Functions:
-Convey sperm into the epididymis
Location, epithelium, support tissues and function: Epididymal duct
LOcation: Head, body, and tail of epididymis
epithelium:
-Pseudostratified columnar with fewer stereocilla
Support tissues:
-Cicular smooth muscle initially with inner and outer longitudinal layers in the tail
functions:
- sperm maturation and short term storage
- expels sperm at ejaculation
Location, epithelium, support tissues and function: Ductus deferens
Location: Extends from epididymis to ejaculatory ducts in prostate gland
epithelium: pseudostratified and simple colimnar
Support tissues:
- Fibroelastic lamina propria
- inner longitudinal, middle circular, outer longitudinal layers of smooth muscle
Function: Carries sperm from the epididymis to the ejaculatory ducts
Location, epithelium, support tissues and function: Ejaculatory ducts
Location: Ductus deferens, ducts of the seminal vesicles that come together located in the prostate
epithelium: Pseudostratified and simple columnar
support tissues:
- Fibroelastic tissue
- smooth muscle
function:
- mix sperm and seminal fluid
- deliver semen to urethra
- prostatic secretion is added here
Characteristics of the epididymis
Highly elongated and coiled duct where sperm mature in the head, body and tail
Pseudostratified columnar with long stereocilla
- principle cells: columnar cells extending from lumen to basal lamina with stereocilla
- stems cells of principle cells
THin circular layer of smooth muscle cells
in tail region have additional inner and outer longitudinal smooth muscle layers
Sperm maturation consists in acquiring forward motility
mature sperm are stored in tail
Characteristics of the Ductus Deferens
A 45 cm long muscular tube lined with pseudostratified columnar epithelia with sparse seterocilla
-supported by CT lamina propria and elastic fibers
Muscular wall:
- inner and outer longitudinal layers
- middle circular layer
- external layer consists of loose CT and adipocytes
Ampulla: dilated portion that leads directly into prostate gland
-distal ends receive the ducts of the seminal vesicle forming the ejaculatory duct
What are the 4 male accessory glands?
seminal vesicles (2x)
Prostate gland
Bulbourethral glands (2x)
Urethral glands
Characteristics of the seminal vesicles
Alkaline secretion rich in fructose and prostaglandins
- contribute to semen (70%)
- excretory duct penetrates the prostate after joining the ductus deferens where they form the ejaculatory duct
Histology:
- External CT capsule
- Highly folded mucosa lined by pseudostratified colimnar epithelium
- inner circular and outer longitudinal smooth muscle
Characteristics of the prostate gland and its various zones
collection of 30-50 tubuloacinar glands that are embedded in a dense fibromuscular stroma, CT capsile
Zones around the urethra:
-Transitional zone (5%): surrounds the superior urethra, contains periurethral mucosal glands
- Central zone (25%): posterior to transition zone, encircles ejaculatory ducts and contains periurethral submucosal glands with longer ducts
- Peripheral (70%) makes up bulk of gland, contains main glands with still longer ducts
individual glads converge but all empty into the prostatic urethra which is the end site of prostatic ducts (prostate secretions) and ejaculatory ducts (semen and secretions from seminal vesicles
histology of prostate gland and function
Glands lined by simple columnar or pseudostratified epithelium
-lumen contains corpora amylacea which contains concretions rich in glycoproteins and Ca deposits
Prostate produces a ZN-rich alakline fluid that neutralizes acidic environment of the vagina
provides nutrients and transports sperm and liquefies the semen
Characteristics of Bulbourethral glands
Clear mucus like secretion that is a makor component to the preseminal fluid
-lubricates the penile urethra and neutralizes traces of acidic urine
Compound tubuloalveolar glands under the control of testosterone
-lined with simple columnar epithelium
Characteristics of the Penis
Consists of cylindrical, columnar masses of erectile tissue
- R/L corpora cavernosa
- ventral corpus spongiosum contains penile urethra
All three erectile tissues comprised of irregular, interconnected vascular sinuses with fibrocollagenous stroma
GLans penis is the distal tip of the corpus spongiosum
Corpora cavernosa are each surrounded by a dense fibroelastic layer, the tunica albuginea
How does the erectile tissue work?
Erection involves blood filling the cavernous spaces of erectile tissues, controlled by ANS in the vascular walls
Parasympathetics relax trabecular smooth muscle and diate the helicane arteries that increases blood flow filling of the cavernous spaces
Enlargement compresses dorsal veins against tunica albuginea and blocks the venous outflow and produces rigidity in erectile tissues
At ejaculation the sympathetics constrict the helicane arteries and trabecular muscle which causes the decrease of blood flow into spaces allowing the veins to drain most of the blood
