Male Histology- Lecture 4 Flashcards
Mediastinum testis
Loose CT surrounds the rete testis, which produces testicular fluid.
Rete Testis
Network of randomly anastomized tubules in the mediastinum, lined by simple cuboidal epithelium.
Ductus epididymis function
Resorption of fluid and androgen binding protein. Sperm maturation. Sperm storage in tail of epididymis (maintenance of sperm viability).
Adventitial cells
One or more layers of cells that are around the seminiferous tubules. Sometimes the innermost layer often modified into myoid cells- squamous cells that contract rhythmically.
Straight tubules
The straightened end of the seminiferous tubules. Lined by simple epithelium (low cuboidal).
Sperm maturation in the ductus epididymus
Migration and loss of cytoplasmic droplet. Acquire fertilizing capacity. Acquire ability to swim. Decapacitation factor coats sperm. Transport time from head, body, tail is 10-15 days.
Sertoli cells (sustentacular cells)
Give nutritive support to developing sperm. Provide proper microenvironment for developing sperm cells. Aid in the release of spermatids into lumen. Sertoli cells are resistant to toxins. Synthesize Mullerian inhibitory Factor (MIF), which causes regression of Mullerian ducts. They form tight junctions that create a blood-testis barrier.
Efferent ductules
Scalloped epithelium- tall ciliated cells, short absorptive cells, secretory cells. Smooth muscle in thin circular layers. Connect the rete testis with the initial section of the epididymis
Ductus deferens
Transport sperm from the epididymis in anticipation of ejaculation.
Vesicular Glands (Seminal Vesicles)
• Compound tubuloacinar leading to the ductus deferens. • Pseudostratified columnar epithelium. • Tunica muscularis present. • Secrete lipids (cholesterol, triglycerides, phospholipids) and glycogen. • Comprises 7-30% of ejaculate, depending on species. • Mucosa of parenchyma and ducts is pseudostratified or simple columnar epithelium • Septa consist of connective tissue and smooth muscle strands
Bulbourethral (Cowper’s)
• Ejaculate contains spermatozoa from epidydimis and seminal fluid from accessory glands. • Ampullae and vesicular glands empty into ductus deferens; prostate and bulbourethral glands empty into urethra. • Ampullae absent in cat, boar. • Vesicular glands absent in carnivores. • Bulbourethral gland absent in dogs.
Accessory Glands
Vesicular (seminal vesicles) Prostate Bulbourethral (Cowper’s)
Interstitial tissue
Surrounding the seminiferous tubules. found in the testi lobules , contain leydig cells and blood vessels.
Seminiferous epithelium of seminiferous tubules
Developing germ cells located here. Spermatogonia and primary spermatocytes are diploid, early spermatid and late spermatid are haploid.
Ductus epididymis histology
Pseudostratified columnar epithelium.
Tunica albuginea
Dense irregular CT, smooth muscle in stallions, stratum vasculare. connective tissue septa divide testis into lobules.
Urethra
By location, has pelvic and penile regions • By structure, has three portions: • prostatic from bladder to prostate • membranous from prostate to bulb • spongiose from bulb distally • Mucosal folds flatten during erection or urination • Tunica muscularis is smooth muscle near bladder, skeletal muscle more distally
Septa
From the tunica albuginea. Divides the testis into lobules, and provides a way for blood vessels to travel in the interstitial tissue.
Penile urethra
Mucosa: • mostly lined by transitional epithelium, but variable • becomes stratified squamous at the urethral opening • Contains mucous glands in horses and pigs Submucosa: • corpus spongiosum - erectile vascular sinuses Muscularis: • sparse smooth muscle
Pelvic urethra
Mucosa: • mucous glands in horses and cats mostly transitional epithelium (similar to bladder). • longitudinal folds. Submucosa: • stratum cavernosum - erectile tissue containing thin-walled veins; analogous to corpus spongiosum of penile urethra. Muscularis: • inner is longitudinal/middle is circular/outer is longitudinal smooth muscle; • striated urethral muscle replaces middle circular layer at prostate
Penis
• Vascular in stallion (cavernous tissue abundant) • Fibroelastic in ruminants, boar (connective tissue predominates). • Dog and cat are intermediate • Erection involves relaxation of smooth muscle in the helicine arteries, leading to increased blood flow into cavernous tissue, compressing veins and reducing outflow.
Testis function
Exocrine: sperm (holocrine secretion) Endrocrine: male sex hormones
Leydig/ interstitial cells
Located in the interstitial region that surrounds the seminiferous tubules. They secrete testosterone. Appear polyhedral, with a large spherical nucleus and have pink cytoplasm. Have foamy cytoplasm due to steroid production.
Bulbourethral (Cowper’s) Gland
• Compound tubular in boar, cat, deer. • Tubuloalveolar in stallion, bull, ram. • Absent in dogs. • Tall columnar epithelium. • Connective tissue capsule contains smooth muscle. • Secretes mucous and glycogen. • Comprises 15-30% of ejaculate, depending on species. • Fibroelastic capsule contains some striated muscle; trabeculae contain smooth and striated muscle
