Male reproductive system-Histology

Question

Answer

What are the main components of the male reproductive system?

The testes, genital ducts, accessory glands, and penis.

What are the two major functions of the testes?

Production of spermatozoa and secretion of male reproductive hormones, mainly testosterone.

What substances combine to form semen?

Spermatozoa plus secretions from the genital ducts and accessory glands.

What is the tunica albuginea?

A capsule of dense connective tissue surrounding the testis.

Where is the tunica albuginea thickened?

On the posterior side of the testis, where it forms the mediastinum testis.

What is the function of the fibrous septa extending from the tunica albuginea?

They divide the testis into approximately 250 testicular lobules.

What is found inside each testicular lobule?

Usually one to four seminiferous tubules surrounded by interstitial loose connective tissue.

What structures are present in the interstitial connective tissue of the testis?

Blood vessels, lymphatic vessels, nerves, and endocrine interstitial cells.

What are Leydig cells?

Endocrine interstitial cells that secrete testicular androgens, especially testosterone.

What is the function of seminiferous tubules?

They produce the male reproductive cells, spermatozoa.

What type of epithelium lines a seminiferous tubule?

A specialized stratified epithelium called the germinal or seminiferous epithelium.

What two major cell populations make up the seminiferous epithelium?

Sertoli cells and proliferative cells of the spermatogenic lineage.

What is the function of myoid cells around seminiferous tubules?

They produce peristaltic waves that help move spermatozoa and testicular fluid.

When does spermatogenesis begin?

At puberty.

In what direction does spermatogenesis progress within a seminiferous tubule?

From the basal region toward the lumen.

What are spermatogonia?

Diploid stem or progenitor cells located near the basal lamina that initiate the spermatogenic lineage.

How are spermatogonia identified histologically?

They have small, dark, ovoid nuclei and are located in the most basal part of the seminiferous epithelium.

What happens to primary spermatocytes?

They enter and undergo meiosis I.

How are primary spermatocytes recognized histologically?

They are the largest germ cells and have relatively large euchromatic nuclei.

How many chromosomes are present in a primary spermatocyte?

Primary spermatocytes are diploid and contain 46 chromosomes.

What happens to secondary spermatocytes?

They enter meiosis II.

Why are secondary spermatocytes rarely seen in histological sections?

They are short-lived because they rapidly proceed through meiosis II.

How many chromosomes do secondary spermatocytes contain?

They are haploid and contain 23 chromosomes.

What are spermatids?

Haploid cells produced after meiosis II that later differentiate into spermatozoa.

How many chromosomes are present in spermatids?

They contain 23 chromosomes.

What is spermiogenesis?

The final differentiation stage in which spermatids become mature spermatozoa.

Does spermiogenesis involve further cell division?

No. It involves cellular remodeling and differentiation without further division.

What major changes occur during spermiogenesis?

The acrosome forms, the flagellum develops, excess cytoplasm is removed, and the nucleus becomes condensed.

Where are mature spermatozoa released?

Into the lumen of the seminiferous tubule.

What is the axonemal microtubule arrangement in the sperm flagellum?

A 9+2 arrangement.

What are the four structural regions of a mature spermatozoon?

The head, neck, middle piece, and tail.

What does the sperm head contain?

A highly condensed nucleus covered by an acrosomal cap.

What is the function of the acrosomal cap?

It contains enzymes needed for penetration of the ovum.

What is the function of the sperm neck?

It connects the head to the tail and organizes the axoneme.

What is found in the sperm middle piece?

A mitochondrial sheath that supplies energy for sperm movement.

What is the primary function of the sperm tail?

Propulsion and movement of the spermatozoon.

What is the general shape of a Sertoli cell?

It is a tall columnar or pyramidal cell.

How are Sertoli cells positioned within the seminiferous epithelium?

They extend from the basal lamina all the way to the lumen and envelop developing germ cells.

What is the appearance of the Sertoli-cell nucleus?

It is elongated, pale, and triangular, with a clear nucleolus.

What membrane specializations are present in Sertoli cells?

Lateral and apical membrane infoldings that help surround and support germ cells.

Which hormone receptor is present on Sertoli cells?

Receptors for follicle-stimulating hormone.

How does follicle-stimulating hormone affect Sertoli cells?

It stimulates Sertoli-cell activity and promotes spermatogenesis.

What is the blood-testis barrier?

A barrier formed by tight occluding junctions between adjacent Sertoli cells.

What are the two compartments created by the blood-testis barrier?

A basal compartment and an adluminal compartment.

Which cells are located in the basal compartment?

Spermatogonia.

Which cells move into the adluminal compartment?

Newly formed spermatocytes and later stages of developing germ cells.

Why is the blood-testis barrier important?

It isolates developing germ cells from the bloodstream and helps protect them from immune reactions.

How do Sertoli cells support spermatogenesis physically?

They surround, organize, and provide structural support for developing germ cells.

What is the phagocytic role of Sertoli cells?

They phagocytize residual bodies discarded during the final stage of spermiogenesis.

What is testicular fluid?

A Sertoli-cell secretion that carries initially nonmotile sperm toward the epididymis.

What is androgen-binding protein?

A Sertoli-cell secretion that concentrates testosterone within the seminiferous tubules.

Which hormone promotes androgen-binding protein production?

Follicle-stimulating hormone.

What is inhibin?

A Sertoli-cell hormone that inhibits follicle-stimulating hormone secretion.

How could inhibin reduce male fertility?

By suppressing follicle-stimulating hormone, it can inhibit spermatogenesis.

What is the role of anti-Müllerian hormone from Sertoli cells?

It causes regression of the embryonic Müllerian ducts.

How do Sertoli cells nourish developing germ cells?

They provide nutrients obtained from nearby capillaries because the germ cells are separated from the blood supply by the blood-testis barrier.

What are Leydig cells like after puberty?

They are rounded or polygonal cells with central nuclei and eosinophilic cytoplasm containing small lipid droplets.

Where is testosterone synthesized within Leydig cells?

By enzymes located in the mitochondria and smooth endoplasmic reticulum.

Which other steroid-producing cells have similar organelles to Leydig cells?

Adrenal cortical cells.

Which hormone stimulates testosterone secretion by Leydig cells?

Luteinizing hormone.

What is the main function of the epididymis?

It stores sperm and allows them to acquire motility and fertilizing ability.

What sperm changes occur in the epididymis?

Sperm acquire motility, zona pellucida protein receptors, acrosomal maturation, and the ability to fertilize.

What type of epithelium lines the epididymis?

Pseudostratified columnar epithelium.

What are the two main epithelial cell types in the epididymis?

Small rounded basal cells and tall principal cells.

What are stereocilia in the epididymis?

Long, branched, irregular microvilli on principal cells.

What are the functions of epididymal epithelial cells?

They absorb water and participate in uptake and digestion of residual bodies.

What is the function of the epididymal muscularis?

Its circular smooth muscle contracts peristaltically to move sperm along the duct.

What are the main histological features of the vas deferens?

A narrow lumen, longitudinal mucosal folds, pseudostratified columnar epithelium with sparse stereocilia, and a very thick muscular wall.

How is the muscularis of the vas deferens arranged?

Inner longitudinal, middle circular, and outer longitudinal smooth-muscle layers.

What is the function of the vas deferens muscularis during ejaculation?

It produces strong peristaltic contractions that propel sperm toward the ejaculatory duct.

What type of autonomic innervation does the vas deferens receive?

Sympathetic innervation.

What is the basic structural arrangement of a seminal vesicle?

Each seminal vesicle consists of one highly coiled tube approximately 15 cm long.

What does the mucosa of the seminal vesicle look like?

It contains thin, branched, anastomosing folds that create a complex honeycomb-like appearance.

What type of epithelium lines the seminal vesicle?

Variable simple columnar or pseudostratified columnar secretory epithelium.

How is the seminal-vesicle muscularis arranged?

As inner circular and outer longitudinal smooth-muscle layers.

What are the major components of seminal-vesicle secretion?

Protein, fructose, vitamin C, and alkaline fluid.

Why is fructose in seminal-vesicle secretion important?

It provides a source of nutrition and energy for sperm.

How many branched tubuloalveolar glands make up the prostate?

Approximately 30 to 50 glands.

What surrounds the prostate glands?

A dense fibromuscular stroma enclosed by a capsule.

How are prostatic glands arranged around the urethra?

In concentric inner mucosal, intermediate submucosal, and outer peripheral groups.

What percentage of the prostate is made up of mucosal glands?

Approximately 5 percent.

What percentage of the prostate is made up of submucosal glands?

Approximately 25 percent.

What percentage of the prostate is made up of the peripheral main glands?

Approximately 70 percent.

Which prostatic zone is the most common site of inflammation and carcinoma?

The peripheral zone.

Where do the ducts of the prostate empty?

Directly into the prostatic urethra.

What epithelial types may occur in the prostate glandular epithelium?

Simple or pseudostratified columnar, low cuboidal, or squamous epithelium.

What is the character of prostatic secretion?

It is a thin, milky, alkaline secretion with a characteristic odor.

Which enzyme is abundant in prostatic secretion?

Acid phosphatase.

What happens to the mucosal and submucosal prostatic glands with age?

They may enlarge after age 40 and compress the urethra.

What symptoms can result from enlargement of the mucosal and submucosal prostate glands?

Pressure on the urethra and difficulty with urination, a condition called senile prostate.

How can prostatic carcinoma be detected biochemically?

By detecting elevated acid phosphatase levels in the plasma.

What are prostatic concretions?

Corpora amylacea formed by condensation of secretory material within prostatic acini.

What happens to prostatic concretions with advancing age?

They become more numerous and may undergo calcification.

What are the three cylindrical masses of erectile tissue in the penis?

Two dorsal corpora cavernosa and one ventral corpus spongiosum.

What structure is surrounded by the corpus spongiosum?

The penile urethra.

What does the corpus spongiosum form at its distal end?

The glans penis.

What epithelium mainly lines the penile urethra?

Stratified columnar epithelium with areas of pseudostratified columnar epithelium.

What type of epithelium covers the glans?

Stratified squamous epithelium continuous with the thin epidermis of the glans.

What are the glands of Littre?

Small mucus-secreting urethral glands distributed along the penile urethra.