Histology of the Male Genital System (2)

The Male Genital System The male genital system consists of: 1. Primary sex organ: two testes. 2. Accessory sex organs: accessory glands and excretory ducts. Accessory glands: seminal vesicle, prostate, bulbo-urethral galnds. Excretory ducts: tubuli recti, rete testis, ductuli efferentes, epididymis, vas deferens, ampulla of vas deferens, ejaculatory duct and urethra. The male genital system consists of: 1. Primary sex organ: two testes. 2. Accessory sex organs: accessory glands and excretory ducts. Accessory glands: seminal vesicle, prostate, bulbo-urethral galnds. Excretory ducts: tubuli recti, rete testis, ductuli efferentes, epididymis, vas deferens, ampulla of vas deferens, ejaculatory duct and urethra.

The Testis

The test is a compound tubular mixed gland formed of stroma and parenchyma The stroma (capsule, septa and reticular connective tissue). The capsule has 3 coats: 1. Tunica vaginalis (parietal and visceral layers) lined with simple squamous epith. 2. Tunica albugenia: condensed collagenous fibers, thickened posteriorly to form the mediastinum testis. 3. Tunica vasculosa: areolar connective Tissue rich in blood capillaries. The test is a compound tubular mixed gland formed of stroma and parenchyma The stroma (capsule, septa and reticular connective tissue). The capsule has 3 coats: 1. Tunica vaginalis (parietal and visceral layers) lined with simple squamous epith. 2. Tunica albugenia: condensed collagenous fibers, thickened posteriorly to form the mediastinum testis. 3. Tunica vasculosa: areolar connective Tissue rich in blood capillaries.

The Testis From the mediastinum testis, incomplete septa arise and extends to the deep surface of the tunica albuginea and divide the testis into 250 compartments or lobules. Each testicular lobule contains 1-4 highly convoluted seminiferous tubules. From the mediastinum testis, incomplete septa arise and extends to the deep surface of the tunica albuginea and divide the testis into 250 compartments or lobules. Each testicular lobule contains 1-4 highly convoluted seminiferous tubules.

Parenchyma of The Testis It divides into exocrine part which produces sperms (seminiferous tubules) and endocrine part which secretes testosterone (interstitial cells of Leydig). Seminiferous tubule is 50 cm in length, 200 micron in diameter, having clear basement membrane surounded by reticular connective tissue and smooth muscle fibers. The seminiferous tubule is lined with two types of cells: 1. Spermatogenic cells: stratified and produce sperms. 2. Sertoli cells: Unilaminar supporting, protective and nutritive cells. It divides into exocrine part which produces sperms (seminiferous tubules) and endocrine part which secretes testosterone (interstitial cells of Leydig). Seminiferous tubule is 50 cm in length, 200 micron in diameter, having clear basement membrane surounded by reticular connective tissue and smooth muscle fibers. The seminiferous tubule is lined with two types of cells: 1. Spermatogenic cells: stratified and produce sperms. 2. Sertoli cells: Unilaminar supporting, protective and nutritive cells.

(1) Spermatogia Spermatogonia: rest on the basement membrane, small cells with small nuclei. At puberty, they divide to give two subtypes of spermatogonia: A. Type A spermatogonia: with fine chromatin granules that stain lightly, some of them remains as stem cells and other redivide to give Type B spermatogonia. B. Type B spermatogonia: larger cells with coarse chromatin granules which stain darkly. They divide to give the primary spermatocytes. Spermatogonia: rest on the basement membrane, small cells with small nuclei. At puberty, they divide to give two subtypes of spermatogonia: A. Type A spermatogonia: with fine chromatin granules that stain lightly, some of them remains as stem cells and other redivide to give Type B spermatogonia. B. Type B spermatogonia: larger cells with coarse chromatin granules which stain darkly. They divide to give the primary spermatocytes.

(2) Primary Spermatocytes Primary spermatocytes are the largest of all spermatogenic cells. Each cell has 23 pairs of chromosomes. Each cell contains coiled chromosomes in their its large nucleus. Each cell undergoes its first meiotic division giving rise to smaller cells called secondary spermatocytes. Primary spermatocytes are the largest of all spermatogenic cells. Each cell has 23 pairs of chromosomes. Each cell contains coiled chromosomes in their its large nucleus. Each cell undergoes its first meiotic division giving rise to smaller cells called secondary spermatocytes.

(3) Secondary Spermatocytes Secondary spermatocytes are the daughter cells of primary spermatocytes. They are small cells with small nuclei having granular chromatin, and live for a short time. Each cell has haploid number of chromosomes (23 only). They enter quickly to the second meiotic division to form spermatids. Secondary spermatocytes are the daughter cells of primary spermatocytes. They are small cells with small nuclei having granular chromatin, and live for a short time. Each cell has haploid number of chromosomes (23 only). They enter quickly to the second meiotic division to form spermatids.

(4) Spermatids Spermatids are very small cells with deeply stained elongated nuclei. They are present in the center of the seminiferous tubule near Sertoli cells. They have haploid number of chromosomes (23) and haploid DNA contents. Each spermatid undergoes a process of spermiogenesis to be transformed into spermatozoon. Spermatids are very small cells with deeply stained elongated nuclei. They are present in the center of the seminiferous tubule near Sertoli cells. They have haploid number of chromosomes (23) and haploid DNA contents. Each spermatid undergoes a process of spermiogenesis to be transformed into spermatozoon.

(5) Mature sperm A Sperm is a highly motile body that consists of: 1) The head: pyriform in shape, formed mainly of the nucleus. Its anterior 2/3 is covered by acrosomal cap which is rich in hydrolytic enzymes that dissolve the zona pellucida of the ovum to facilitaate fertilization. 2) The tail: which is subdivided into four parts: 1.The neck: containing the centrioles. 2.The middle piece: containing the mitochondria. 3.The principal piece: containing outer fibrous sheath. 4.The end piece: central axoneme surounded by plasmalemma. A Sperm is a highly motile body that consists of: 1) The head: pyriform in shape, formed mainly of the nucleus. Its anterior 2/3 is covered by acrosomal cap which is rich in hydrolytic enzymes that dissolve the zona pellucida of the ovum to facilitaate fertilization. 2) The tail: which is subdivided into four parts: 1.The neck: containing the centrioles. 2.The middle piece: containing the mitochondria. 3.The principal piece: containing outer fibrous sheath. 4.The end piece: central axoneme surounded by plasmalemma.

DefinitionsDefinitions Spermatogenesis: formation of sperms from spermatogonic cells. It divides into 3 phases: 1. Spermatocytogenesis: spermatogonia (2n chromosomes and 2n DNA) give primary spermatocytes (2n chromosomes and 2n DNA). 2. Meiosis: which subdivides into: 1.First meiotic division: primary spermatocytes (2n chromosomes and 4n DNA) give secondary spermatocytes (n chromosomes and 2n DNA). 2.Second meiotic division: secondary spermatocytes give spermatids (n chromosomes and n DNA). 3. Spermiogenesis: differentiation of spermatids into mature sperms Spermatogenesis: formation of sperms from spermatogonic cells. It divides into 3 phases: 1. Spermatocytogenesis: spermatogonia (2n chromosomes and 2n DNA) give primary spermatocytes (2n chromosomes and 2n DNA). 2. Meiosis: which subdivides into: 1.First meiotic division: primary spermatocytes (2n chromosomes and 4n DNA) give secondary spermatocytes (n chromosomes and 2n DNA). 2.Second meiotic division: secondary spermatocytes give spermatids (n chromosomes and n DNA). 3. Spermiogenesis: differentiation of spermatids into mature sperms

SpermiogenesisSpermiogenesis Spermiogenesis: differentiation of spermatids into mature sperms: 1. Formation of the acrosomal cap. 2. Elongation, condensation and flattening of the nucleus. 3. Changes in the centrioles and fomation of the flagellum. 4. Arrangement of the mitochondria as a spiral structure around the first part of the tail. 5. Discharge of the cytoplasm and other organelles of no use by the sperm. Spermiogenesis: differentiation of spermatids into mature sperms: 1. Formation of the acrosomal cap. 2. Elongation, condensation and flattening of the nucleus. 3. Changes in the centrioles and fomation of the flagellum. 4. Arrangement of the mitochondria as a spiral structure around the first part of the tail. 5. Discharge of the cytoplasm and other organelles of no use by the sperm.

Sertoli Cells They are pyramidal-shaped cells resting on the basement membrane of the seminiferous tubule and extend till its lumen. They are interposed between the spermatogenic cells. They have pale cytoplasm containing RER, SER, Golgi apparatus, lysosomes, lipid droplets, glycogen granules, microtubules, filaments and mitochondria. They have large, basal, elongated euchromatic nuclei. The basal part of the lateral walls are united by tight junctions which constitute blood-testis barrier. They are pyramidal-shaped cells resting on the basement membrane of the seminiferous tubule and extend till its lumen. They are interposed between the spermatogenic cells. They have pale cytoplasm containing RER, SER, Golgi apparatus, lysosomes, lipid droplets, glycogen granules, microtubules, filaments and mitochondria. They have large, basal, elongated euchromatic nuclei. The basal part of the lateral walls are united by tight junctions which constitute blood-testis barrier.

Blood-testis barrier It is the tight junctions between the basal parts of the Sertoli cells which isolate the spermatogonia from the other spermatogenic cells. This barrier divides the seminiferous tubules into basal compartment (containing spermatogonia) and adluminal compartment (containing spermatocytes, spermatids and sperms). Functions of blood-testis barrier: 1.Selects the nutrients, hormones and other structures needed for the spermatogenic cells. 2.Isolates and protects the spematogenic cells from any damaging materials, antigen or antibodies in the circulating blood. 3.Prevents leakage of testicular fluid and androgen- binding protein secreted by Sertoli cells to the interstitial tissues. It is the tight junctions between the basal parts of the Sertoli cells which isolate the spermatogonia from the other spermatogenic cells. This barrier divides the seminiferous tubules into basal compartment (containing spermatogonia) and adluminal compartment (containing spermatocytes, spermatids and sperms). Functions of blood-testis barrier: 1.Selects the nutrients, hormones and other structures needed for the spermatogenic cells. 2.Isolates and protects the spematogenic cells from any damaging materials, antigen or antibodies in the circulating blood. 3.Prevents leakage of testicular fluid and androgen- binding protein secreted by Sertoli cells to the interstitial tissues.

Functions of Sertoli Cells 1. Support, protection, nutrition, regulation and release of sperms. 2. Phagocytosis of degenerative cells and debris. 3. Secretion of testicular fluid and androgen-binding proteins. 4. Formation of blood-testis barrier. 5. Secretion of small amounts of testosterone. 1. Support, protection, nutrition, regulation and release of sperms. 2. Phagocytosis of degenerative cells and debris. 3. Secretion of testicular fluid and androgen-binding proteins. 4. Formation of blood-testis barrier. 5. Secretion of small amounts of testosterone.

Interstitial cells of Leydig They are mesenchymal cells, rounded or polygonal in shape. They have euchromatic central nuclei and acidophilic cytoplasm. The cytoplasm is rich in SER and lipid droplets. It also contains RER, Golgi apparatus, lysosomes and lipofuscin pigments. They form the endocrine part of the testis because they produce and secrete the testosterone under the control of ICSH (LH) of the anterior lobe of the pituitary gland. They are mesenchymal cells, rounded or polygonal in shape. They have euchromatic central nuclei and acidophilic cytoplasm. The cytoplasm is rich in SER and lipid droplets. It also contains RER, Golgi apparatus, lysosomes and lipofuscin pigments. They form the endocrine part of the testis because they produce and secrete the testosterone under the control of ICSH (LH) of the anterior lobe of the pituitary gland.

Male Genital Ducts. 1. Tubuli recti. 2. Rete testis. 3. Efferent ductules. 4. Epididymis. 5. Vas deferens. 6. Ejaculatory duct. 7. Male urethra. 1. Tubuli recti. 2. Rete testis. 3. Efferent ductules. 4. Epididymis. 5. Vas deferens. 6. Ejaculatory duct. 7. Male urethra.

The Tubuli Recti They have narrow diameter and are lined by simple columnar epithelium. They connect the sminiferous tubules with the rete testis. They have narrow diameter and are lined by simple columnar epithelium. They connect the sminiferous tubules with the rete testis. The Rete Testis They are located in the mediastinum testis and forms a network of anastomosing channels surrounded by vascular bed. They are lined by cuboidal epithelium. They are located in the mediastinum testis and forms a network of anastomosing channels surrounded by vascular bed. They are lined by cuboidal epithelium.

Efferent Ductules They connect the rete testis to the head of the epididymis. They are lined by two types of cells: 1. Low columnar non-ciliated cells (for absorption of testicular fluid). 2. High columnar ciliated cells (for moving the non-motile sperms toward the epididymis). The cells rest on basement membrane which is surrounded by connective tissue containing elastic fibers and smooth muscle fibers. The lumen of the efferent ductules appears as festooned because of the alternating tall and short columnar epithelial cells. They connect the rete testis to the head of the epididymis. They are lined by two types of cells: 1. Low columnar non-ciliated cells (for absorption of testicular fluid). 2. High columnar ciliated cells (for moving the non-motile sperms toward the epididymis). The cells rest on basement membrane which is surrounded by connective tissue containing elastic fibers and smooth muscle fibers. The lumen of the efferent ductules appears as festooned because of the alternating tall and short columnar epithelial cells.

EpididymisEpididymis It is a highly coiled 6 m. tube lined with pseudostratified ciliated columnar epithelium. The cilia are non-motile (stereocilia). The epithelium rests on basement membrane surrounded by vascular connective tissue containing smooth muscle fibers and elastic fibers. Its functins are absorption of the testicular fluid, storage and maturation of the sperms and propulsion of the sperms during ejaculation. It is a highly coiled 6 m. tube lined with pseudostratified ciliated columnar epithelium. The cilia are non-motile (stereocilia). The epithelium rests on basement membrane surrounded by vascular connective tissue containing smooth muscle fibers and elastic fibers. Its functins are absorption of the testicular fluid, storage and maturation of the sperms and propulsion of the sperms during ejaculation.

Vas deferens It is a 45 cm tube with a narrow lumen and thick muscular wall which is formed of: 1. Mucosa: lined with pseudostratified ciliated columnar epithelium and lamina propria rich in elastic fibers. 2. Musculosa: inner and outer longitudinal layers and middle circular layer of smooth muscle fibers. 3. Adventitia: of loose connective tissue with elastic fibers. The muscle fibers contract forcibly during ejaculation of sperms. It is a 45 cm tube with a narrow lumen and thick muscular wall which is formed of: 1. Mucosa: lined with pseudostratified ciliated columnar epithelium and lamina propria rich in elastic fibers. 2. Musculosa: inner and outer longitudinal layers and middle circular layer of smooth muscle fibers. 3. Adventitia: of loose connective tissue with elastic fibers. The muscle fibers contract forcibly during ejaculation of sperms.

Seminal Vesicle They are two highly coiled tubes (5-7 cm) embedded in smooth muscle and connective tissue. Each gland has three layers: Mucosa: highly folded, lined by pseudostratified columnar epithelium and lamina propria of connective tissue containing elastic fibers. Musculosa: inner circular and outer longitudinal. Adventitia: areolar connective tissue and elastic fibers. They are two highly coiled tubes (5-7 cm) embedded in smooth muscle and connective tissue. Each gland has three layers: Mucosa: highly folded, lined by pseudostratified columnar epithelium and lamina propria of connective tissue containing elastic fibers. Musculosa: inner circular and outer longitudinal. Adventitia: areolar connective tissue and elastic fibers.

Function of Seminal Vesicle It secretes yellow viscous nutrient secretion containing: fructose, ascorbic acid (vitamin C), citric acid and prostaglandins which: 1. Shares in formation of the fluid medium of the semen. 2. Important for the sperm metabolism and nutrition. 3. Prostaglandins help in the effectiveness of sperms inside the female reproductive tracts. It secretes yellow viscous nutrient secretion containing: fructose, ascorbic acid (vitamin C), citric acid and prostaglandins which: 1. Shares in formation of the fluid medium of the semen. 2. Important for the sperm metabolism and nutrition. 3. Prostaglandins help in the effectiveness of sperms inside the female reproductive tracts.