Male Histology- Lecture 4

Question 1

Mediastinum testis

Answer 1

Loose CT surrounds the rete testis, which produces testicular fluid.

Question 1

Rete Testis

Answer 1

Network of randomly anastomized tubules in the mediastinum, lined by simple cuboidal epithelium.

Question 1

Ductus epididymis function

Answer 1

Resorption of fluid and androgen binding protein. Sperm maturation. Sperm storage in tail of epididymis (maintenance of sperm viability).

Question 2

Adventitial cells

Answer 2

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.

Question 2

Straight tubules

Answer 2

The straightened end of the seminiferous tubules. Lined by simple epithelium (low cuboidal).

Question 2

Sperm maturation in the ductus epididymus

Answer 2

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.

Question 3

Sertoli cells (sustentacular cells)

Answer 3

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.

Question 4

Efferent ductules

Answer 4

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

Question 5

Ductus deferens

Answer 5

Transport sperm from the epididymis in anticipation of ejaculation.

Question 6

Vesicular Glands (Seminal Vesicles)

Answer 6

• 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

Question 7

Bulbourethral (Cowper’s)

Answer 7

• 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.

Question 8

Accessory Glands

Answer 8

Vesicular (seminal vesicles) Prostate Bulbourethral (Cowper’s)

Question 9

Interstitial tissue

Answer 9

Surrounding the seminiferous tubules. found in the testi lobules , contain leydig cells and blood vessels.

Question 10

Seminiferous epithelium of seminiferous tubules

Answer 10

Developing germ cells located here. Spermatogonia and primary spermatocytes are diploid, early spermatid and late spermatid are haploid.

Question 11

Ductus epididymis histology

Answer 11

Pseudostratified columnar epithelium.

Question 12

Tunica albuginea

Answer 12

Dense irregular CT, smooth muscle in stallions, stratum vasculare. connective tissue septa divide testis into lobules.

Question 13

Urethra

Answer 13

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

Question 15

Septa

Answer 15

From the tunica albuginea. Divides the testis into lobules, and provides a way for blood vessels to travel in the interstitial tissue.

Question 16

Penile urethra

Answer 16

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

Question 17

Pelvic urethra

Answer 17

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

Question 18

Penis

Answer 18

• 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.

Question 20

Testis function

Answer 20

Exocrine: sperm (holocrine secretion) Endrocrine: male sex hormones

Question 21

Leydig/ interstitial cells

Answer 21

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.

Question 22

Bulbourethral (Cowper’s) Gland

Answer 22

• 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

Question 24

Sertoli cells synthesize…

Answer 24

MIF- mullerian inhibitory factor. Androgen binding protein- to trap testosterone. Inhibin- inhibits FSH secretion by the pituitary. Gonadocrinins- inhibit leydig cells.

Question 26

Intertubular and peritubular capillaries

Answer 26

Surround seminiferous tubules. Responsible for transporting hormones, and nutrients for spermatogenesis.

Question 27

Prostate Gland

Answer 27

Body of prostate wraps around pelvic urethra. Disseminate portion is embedded in the lamina propria/ submucosa of pelvic urethra. • Stallion has only body; some ruminants have only disseminate portion. • Compound tubuloalveolar tissue. • Cuboidal or columnar epithelium. • Connective tissue capsule contains smooth muscle. • Secretes proteins and lipids. • Comprises 4-60% of ejaculate, depending on species.

Question 28

Blood-testis barrier

Answer 28

Tight junctions formed by sertoli cells. Divides seminiferous tubules into basal and apical compartments; protects spermatocytes and spermatids for meiosis and maturation.

Question 29

Vas deferens

Answer 29

Contains the Ductus Deferens. Transports sperm from the epididymis in anticipation of ejaculation, thick tunica muscularis.

Question 30

Ampullary glands

Answer 30

• Located where the ductus deferens enters the urethra. • Present in stallion, ruminants, dog. • Absent in boar, cat. • Contributes to the seminal fluid. • Glycogen and lipids secreted. • Branched tubuloalveolar glands. • Rich in glycogen and lipid droplets which are added to the seminal fluid.