Lecture_9_ANSC2400

Spermatogenesis occurs within the

Seminiferous Tubules

Tubular Compartment (of the Parenchyma), contains

Seminiferous Tubules, Sertoli Cells

Spermatogenesis occurs here

Seminiferous tubules (highly convoluted)

What kind of epithelium is found in Efferent Ducts?

Simple columnar epithelium

Interstitial Compartment

Space in between the tubular compartment (seminiferous tubules). Containing Capillaries, lymph vessels, connective tissue

Exocrine Product of Testes

Sperm

Functions of The Epididymis

Sperm mature, are concentrated, and stored in epididymis

What happens to sperm that are not ejaculated?

Sperm that are not ejaculated and die will breakdown and their components absorbed by the epididymis

Seminiferous tubules contain two types of cells

Spermatogenic cells & Sertoli cells

Spermatic cord

Suspends testes, temperature regulation, houses nerves/vasculature

Where Sperm is stored prior to ejaculation

Tail of Epididymis

4 main parts of the Testes

Testicular capsule Testicular Parenchyma Mediastinum Rete testis

LH stimulates production of

Testosterone & Oxytocin

Endocrine Product of Testes

Testosterone, AMH, Estrogen, Inhibin

Cytoplasmic droplet of sperm are lost in what part of the Male Reproductive Tract

The Epididymis

Microenvironments are seen in which portion of the male repro tract

The epididymis is one tubule, but has different microenvironments

Parenchyma has two compartments:

Tubular Compartment & Interstitial Compartment

Testicular Capsule contains the

Tunica albuginea (and vasculosa), & Visceral Vaginal Tunic

Some mammals that have internal (retroperitoneal) testes

Whales, Birds

Clear Cells function

acidify lumen (keep sperm quiescent) in the epididymis

Secretions in epididymosomes results in

altered sperm function

FSH & Testosterone synergize to produce

androgen binding protein (ABP)

Seminiferous tubules are surrounded by

by a basement membrane, fibro-muscular connective tissue, and myoid (peritubular) cells

The blood-epididymis barrier (BEB) formed by

by tight junctions between epithelial cells

Basal compartment of seminiferous tubule

closest to basement membrane. Has Spermatogonia, Sertoli cells

Adluminal compartment of seminiferous tubule

closest to lumen. Has spermatocytes, spermatids, sperm

Visceral vaginal tunic

closest to testes, covers tunica albuginea and testes

Excurrent duct system

conveys sperm and fluid from testes to urethra

Parietal vaginal tunic Function

covers testes and spermatic cord, innermost layer of scrotum

Leydig cells have receptors for Estrogen that can result in

decrease testosterone

Tunica Albuginea

dense irregular connective tissue and smooth muscle. Lined by simple cuboidal

Projections from Tunica Albuginea results in

divided testis into lobules packed with Seminiferous tubules

Presence of cytoplasmic droplet in ejaculated sperm suggests

dysfunction of epididymis

Tight junctions function in Sertoli cells

establish the blood-testis barrier, protecting germ cells from the immune system

Sertoli cells secrete

estrogen, androgen-binding protein (ABP), anti-mullerian hormone (AMH), Inhibin, fructose-rich nutritive medium, transferrin, sulfated glycoproteins (SGP1, SGP2)

Sulfated Glycoproteins (SGP1 and SGP2) important for

fertility acquisition

Estrogen may regulate

fluid reabsorption in epididymis

Estrogen receptor of Epididymis knocked-out mice resulted in

fluid reabsorption inhibited, epithelial cells reduced numbers organelles associated with endocytosis.

Why are testes kept at a lower Temperature?

for spermatogenesis (most mammals are housed externally in the scrotum)

Leydig cells have receptors for Oxytocin that can result in

increases testosterone (rat)

Tunica vasculosa

is interior to tunica albuginea and houses vasculature

Basal Cell function

monitor lumen pH, regulate clear cells in the epididymis

Vaginal tunics are derived from

peritoneum (serous membrane that covers abdominal cavity)

Accessory Sex Glands

produce components of seminal fluid

Sertoli Cells produce what kind of fluid?

rete fluid

Seminiferous tubules "empty" into

rete testis

Principle Cell (with stereocilia) Function

secretory, absorb fluid, alter fluid content in the epididymis

Seminiferous tubules have what kind of epithelium?

stratified germinal epithelium (layered cells that produce sperm)

Sertoli Cells function

surround, support, protect and nourish spermatogenic cells & act as nurse cells

Number of fertile breedings limited by sperm reserves in the

tail of Epididymis. Increased frequency of ejaculation decreases total sperm in ejaculate

Extragonadal Reserve (EGR) of sperm

total sperm in epididymis, ductus deferens, and ampulla

Epididymal Transit Time (ETT)

Amount of time required for sperm to transport from head to tail of epididymis

What regulates the Epididymis?

Androgens & Estrogen

Seminiferous tubules have 2 compartments

Basal & Adluminal

Interstitial Compartment (of the Parenchyma), contains

Blood vessels, Leydig Cells

Mediastinum

Central connective tissue core that houses Rete Testis. Prevents tubules from collapsing.

Function of non/ciliated in Efferent Ducts

Ciliated (circulate fluid) & non-ciliated (absorptive)

Efferent Ducts function

Convey sperm and tubular (rete) fluid from rete testis to epididymis

Rete testis have what kind of epithelium?

Cuboidal epithelial with cilia for moving & microvilli for absorbing/altering fluid

Excurrent Duct System has three main structures

Efferent Ducts, Epididymis, Ductus Deferens

Inhibin and Estrogen have Negative feedback

FSH

How does FSH stimulate Sertoli cells

FSH stimulates Inhibin and ABP production (T enhances Androgen-Binding Protein)

Epididymis three components

Head (caput), Body (corpus), Tail (Cauda)

Scrotum

Houses testes externally, temperature regulation

Penis

Male copulatory organ

Anti-Mullerian Hormone (AMH) causes regression of

Mullerian (female) ducts

How does Oxytocin assist with sperm movement in seminiferous tubules?

Oxytocin may act on myoid cells surrounding seminiferous tubules to cause contractions and move sperm

Leydig cells

Produce Testosterone & Oxytocin (smooth ER)

Testes

Produce gametes (sperm) and hormones (testosterone, inhibin)

Muscles in Male Tract

Protrusion, erection, ejaculation

Species that descend (external)/ascend (internal) based on breeding season

Rabbit, some rodents

What's the path from Rete Testes to the Ductus Deferens?

Rete Testes --> Efferent Ducts --> Epididymis --> Ductus Deferens