Male Genital System PDF

1. Two Testes Components 2. Genital ducts Intratesticular Tubuli Recti (Straight Tubules) Rete Testis Efferent ductules Extratesticular Ductus Epididymis Ductus (Vas) Deferens Ejaculatory Duct 3. Accessory Glands Prostate, Seminal vesicles, Bulbourethral...

1. Two Testes Components 2. Genital ducts Intratesticular Tubuli Recti (Straight Tubules) Rete Testis Efferent ductules Extratesticular Ductus Epididymis Ductus (Vas) Deferens Ejaculatory Duct 3. Accessory Glands Prostate, Seminal vesicles, Bulbourethral glands of Cowper glands of Littre 4. External genitalia Scrotum Penis  The male reproductive system 1. The dual function of the testis is to produce spermatozoa and hormones. 2. The genital ducts and accessory glands produce secretions that, aided by smooth muscle contractions, conduct spermatozoa toward the exterior.  Spermatozoa and the secretions of the genital ducts and accessory glands make up the semen.  Testosterone is the main hormone produced in the testes, both testosterone and one of its metabolites, dihydrotestosterone, are necessary for the physiology of men.  Cryptorchidism: Descend of the testis is sometimes obstructed resulting in cryptorchidism or undescended testis. It may lead to irreversible histological changes in the testis approximately at 2 years of age. So, undescended testis requires surgical correction before these histological changes becomes irreversible 1. Testes A. Stroma (CT component): 1. Each testis is surrounded A.tunica vaginalis B.Tunica albuginea is thickened on the posterior surface of the testis to form the mediastinum testis C. Tunica vasculosa (highly vascular) 2. Septa From which incomplete fibrous septa penetrate the gland, dividing it into about 250 pyramidal compartments called the testicular lobules 3. Reticular network B. Parenchyma (Epithelial Tissue component): 1. The exocrine portion is composed of: A.Seminiferous tubules (Secretory part): produce sperm B.Conducting part: intratesticular ducts (Tubuli recti &Rete testes) 2. The endocrine portion (Leydig cells) Secrete testosterone H  A. Seminiferous Tubules Highly convoluted tubules 150-250 µm in diameter and 30-70 cm long. Each tubule has a well-developed basal lamina Surrounded by a connective tissue containing Type I collagen fibers & Fibroblasts Smooth muscle cells called myoid cells Lined with complex stratified epithelium Spermatogenic cells Supporting or Sertoli cells In-between the tubules: Interstitial (Leydig) cells occupy much of the space between the seminiferous tubules.  I. Spermatogenic Cells Formed of stratified germinal (seminiferous) epithelium 1. Spermatogonia 2. Primary spermatocytes (46d chromosomes) 3. Secondary spermatocytes (23d chromosomes) 4. Spermatids (s chromosomes)  1. Spermatogonia 1-Dark type–A spermatogonia Undifferentiated stem cells Dark stained oval nuclei. They divide to form pale type-A cells and dark type-A cells 2-Pale type -A spermatogonia Similar to dark type-A cells but with pale- stained oval nuclei They give pale type-A cells and type-B spermatogonia 3-Type-B spermatogonia Similar to pale type A cells round pale nucleus They give rise to primary spermatocytes that migrate toward the lumen Before puberty testes contain only Spermatogonia  2. Primary Spermatocytes The Largest cells of the seminiferous epithelium. Have round, large, vesicular nuclei contain 46d chromosomes. Start the first meiotic division By the end of the first meiotic division every primary spermatocyte forms 2 secondary spermatocytes having 23 d chromosomes.  3. Secondary Spermatocytes Site: difficult to be seen in the section. Size: smaller than primary spermatocytes. Nucleus:  23 d-chromosome (with either X or Y chromosome). Changes: second meiosis to produce: spermatids (each having 23 s- chromosome).  4. Spermatids Site: attached to the apex of Sertoli cells. Size: the smallest (9 µm). Shape: elongated cells. Nucleus:  23 s-chromosome (with either X or Y s chromosomes). Changes: undergo spermiogenesis to form mature spermatozoa.  Spermatogenesis It takes about 64 days Divided into : A. Spermatocytogenesis  Mitosis.  Meiosis. B. Spermiogenesis. A. Spermatocytogenesis  B. Spermiogenesis Is the final stage of production of spermatozoa. Definition: Morphological changes in spermatids to produce mature spermatozoon (sperm). No division. Spermatids transformed into spermatozoa Divided into 4 phases: 1. Golgi phase 2. Cap phase 3. Acrosomal phase 4. Maturation phase  B. Spermiogenesis 1. Golgi phase Small proacrosomal vesicles from the Golgi apparatus coalesce as a single membrane-limited acrosomal cap close to one end of the nucleus The centrioles migrate to opposite end of the nucleus and one acts as a organizing the axoneme of the flagellum. 2. Cap phase The acrosomal cap spreads over about half of the condensing nucleus. It contains hydrolytic enzymes. 3. Acrosome phase Nuclei become more elongated and very highly condensed. The acrosomal cap spreads over about 2/3 of the nucleus. Mitochondria aggregate around the flagellum proximal region to form a thickened middle piece. 4. Maturation phase Unneeded cytoplasm is shed as a residual body. Mature but not yet functional sperm. Spermatozoa Normal sperm count is 80-120 million/ml About 20% of sperms may be morphologically abnormal Sperm length about 65 um It is formed of 1. Head 2. Neck 3. Tail a. Middle piece b. Principle piece c. End piece  Spermatozoa 1. Head The nucleus densely-packed. Acrosome covered its anterior two- thirds. 2. Neck Connecting head & middle piece. 3. Tail: A. Middle Piece from outside to inside: Surrounded by circumferentially oriented Mitochondria Nine longitudinally oriented fibrous sheaths Axoneme B. Principal piece C. End piece  Sertoli cells They are elongated pyramidal cells. The nucleus is large, basal and pale with prominent nucleolus Its bases of the Sertoli cells adhere to the basal lamina, and their apical ends frequently extend into the lumen. Lateral pocket in the cell membrane enclose spermatogenic cells. Tight junction between their lateral membranes (Blood testes barrier) As the flagellar tails of the spermatids develop, they appear as tufts extending from its apical ends Functions of Sertoli Cells 1. Supporting & movement of spermatogenic cells. 2. Nutrition Phagocytosis of residual bodies of spermatids 3. Endocrine function: A. Androgen- binding protein (ABP) : stimulate spermatogenesis. B. Inhibin hormone that inhibits the release of FSH: Inhibit spermatogenesis. 4. Formation of Blood Testes Barrier.  Blood Testis Barrier  Continuous tight junctions between Sertoli cells.  Divides the seminiferous tubule into 2 compartments: 1.Outer (basal) compartment: Only spermatogonia. 2.Inner (adluminal) compartment: Primary spermatocytes. Secondary spermatocytes. Spermatids. Mature spermatozoa. Function of Blood Testis Barrier 1. Select passage of nutrients and hormones: needed for differentiation of spermatogenic cells. 2. Isolate and protect spermatocytes and spermatids from damaging substances in the blood stream. 3. Prevents the interaction between developing sperms and the immune system. 4. Maintain high concentration of electrolytes and ABP in the inner compartment. Interstitial cell of Leydig Site: in the interstitial tissue of the testis (between seminiferous tubules). Starts its function just before puberty under influence of LH.  Large cell with active (euchromatic) nucleus and vacuolated cytoplasm.  The cytoplasm is rich in mitochondria, sER and Lipid droplets. Function : Synthesis & secretion of testosterone hormone.  Genital Ducts 1. Intratesticular ducts Tubuli Recti (Straight tubules) Rete Testis Efferent ductules  Genital Ducts 2. Extra-testicular ducts 1. Ductus Epididymis 2. Ductus (Vas) Deferens 3. Ejaculatory Duct 1. Ductus Epididymis 1.Histologically, it consists of: 1. Mucosa: 1. Epithelial lining: Pseudostratified columnar epithelium with stereocilia. 2. Lamina propria : vascular connective tissue. 2. Musculosa: Is organized into three layers:  Inner and outer layers of longitudinal smooth muscle fibers  Middle layer of circular fibers. 3. Adventitia: C.T. invests the musculosa. 2. Ductus (vas) deferens Histologically it consists: 1. Mucosa: Epithelial lining: Pseudostratified columnar epithelium with stereocilia. Lamina propria contains an abundance of elastic fibers. 2. Musculosa: The muscular wall of the vas is very thick. The muscle is organized indistinctly into three layers: Inner and outer layers of longitudinal smooth M. fibers Middle layer of circular Smooth M. fibers. 3. Adventitia: Connective tissue invest the musculosa 3. Ejaculatory Duct Ejaculatory duct is formed by joining Of : The ampulla of vas deference The duct of seminal vesicle. It penetrates the prostate gland to open in prostatic urethra The spermatic cord formed of : 1. Vas deferens 2. Cremasteric muscle 3. Testicular artery and vein 4. Pampiniform plexus of veins 5. Lymphatic vessels and nerves All these structures are surrounding by fascial coverings  Accessory Genital Glands 1. Prostate 2. Seminal vesicle 3. bulbourethral glands of Cowper 4. glands of Littre  1. Prostate The prostate gland is the largest accessory sex gland. It is a single gland lying immediately below the urinary bladder Structure:(compound tubuloalveolar exocrine glands). 1. Stroma: it is a fibromuscular as it contains smooth muscle fibers distributed in all parts of it. Capsule Septa Reticular network 2. Parenchyma: Secretory part. Conducting part.  2. Parenchyma: A. Secretory part: The acini are arranged into 3 concentric zones : 1. Central zone: Small. Beside urethra. 2. Transition zone: larger. Peripheral to mucosal acini. 3. Peripheral zone: The largest. Most peripheral. Depending on the activity of the gland, acinus may be lined with: Pseudo stratified columnar. Simple columnar cells. Simple cubical cells. In old age, the lumen of the acini contains prostatic concretions called corpora amylacea. B. Conducting part: Is formed of branched ducts and the main ducts (12-20) open into the prostatic urethra.  2. Seminal vesicle A pair of simple tubular glands. They are coiled on themselves to form two bodies. Epithelial lining: Pseudostratified columnar epithelium. 3. Bulbourethral Glands Of Cowper They are paired gland located in urogenital diaphragm at the root of penis and opens in membranous urethra. It is a compound mucous tubuloalveolar exocrine gland. Structure: Stroma: as prostate Parenchyma: mucous acini lined by cuboidal or columnar epithelium. 4. Glands Of Littré Multiple paraurethral compound mucous tubuloalveolar exocrine gland located along the full length of the corpus spongiosum. Thank You