Histology of Male Genital System (215 PSL) PDF

HISTOLOGY 215 PSL MALE GENITAL SYSTEM 21 5 P S L  Lecture Objectives  Describe the histological structure?  Its relation to function and some clinical problems? It is formed of: 1. Testis. 2. Epididymis. 3. Vas deferens. 4. Seminal vesicle. 5. Prostate. 6. Penis.  Male...

HISTOLOGY 215 PSL MALE GENITAL SYSTEM 21 5 P S L  Lecture Objectives  Describe the histological structure?  Its relation to function and some clinical problems? It is formed of: 1. Testis. 2. Epididymis. 3. Vas deferens. 4. Seminal vesicle. 5. Prostate. 6. Penis.  Male genital system It comprises: 1. Primary genital organs: two testes. 2. Genital ducts :intra testicular and extra testicular genital ducts. 3. Accessory genital glands: the seminal vesicle, the prostate, the bulbo urethral glands of Cowper and the glands of Littre. 4. External genitalia :the penis and the scrotum. Testis The testis is a compound tubular mixed gland. The Coverings of The Testis I- The scrotum: outside the body to maintain the testis at subnormal temperature essential for the production of the spermatozoa. The wall of the scrotum is formed of: 1- Thin skin with no hypodermis. 2- Dartos muscle: smooth muscle fibers. 3- Spermatic fascia: is a thin layer of areolar C.T. II-The tunica vaginalis: Is a pouch of peritoneum , formed of simple squamous mesothelium. It is formed of two layers: a- Visceral layer, covering the testis. b- Parietal layer lining the scrotum. Structure of the testis: Each testis is formed of: 1-Stroma of C.T. 2-Parenchyma of exocrine and endocrine cells. Stroma of the testis: a) The tunica albuginea: a capsule of dense collagenous CT b) The tunica vasculosa: areolar C.T. rich in blood capillaries. c) The connective tissue septa : divide the testis into about 250 compartments. Each testicular lobule contains 1-4 convoluted seminiferous tubules. Parenchyma of the testis: consists of: I- Seminiferous tubules: The exocrine parts produce spermatozoa. II- Interstitial cells of Leydig: The endocrine part produce testosterone hormone. Seminiferous tubules  Are highly convoluted tubules.  The epithelium lining of seminiferous tubules consists of : 1- Spermatogenic cells. 2- Sertoli cells.  SPERMATOGENIC CELLS Spermatogenesis: SPERMATOGONIA SPERMATOZOA Spermatocytogenesis: Spermatogonia Primary Spermatocytes: Meiosis SPERMATID Spermiogenesis: Spermatids spermatozoa 1- Spermatogonia 1-Type A dark spermatogonia: (dark chromatin) Divide to give active type A pale spermatogonia (pale chromatin ). Divide to give another type A pale types and type B. Spermatogonia. Type B Spermatogonia: divide by mitosis to give primary spermatocytes. 2- Primary spermatocytes The largest cells, arranged in two or three layers. Nuclei contains 46 chromosome. Enter the first meiotic division at puberty giving secondary spermatocytes.  Histology 232ANAT ِِMale Genital system 3- Secondary spermatocytes: Nuclei :contain 23 chromosomes;enter the second meiotic division (So they are rarely seen in sections) giving two spermatids each containing 23 chromosomes). 4- Spermatids: Occupy the center of the seminiferous tubules. Are the smallest spermatogenic cells. Do not divide but undergo a process of differentiation called spermiogenesis or metamorphosis which results in the transformation of spermatids into spermatozoa. During division of the spermatogonia, the resulting cells do not separate completely but remain attached by cytoplasmic bridges results in formation of syncytium of cells. Spermatids SPERMIOGENESIS sperms Spermiogenesis: Includes formation of: 1. Acrosomal head cap. 2. Formation of a flagellum. 3. Migration of mitochondria. 4. Formation of the head of spermatozoon. Structure of a mature sperm 1) Head: formed of nucleus contains 23 chromosomes. The anterior 2/3 is covered by the acrosome which is rich in hydrolytic enzymes. 2) Neck: connecting the head to the middle piece. 3) Middle piece: between the neck and the principal piece and contain mitochondria. 4) Tail: Contain axoneme.  SERTOLI CELLS Tall pyramidal cells, present between the spermatogenic cells. Bases are resting on the basement membrane. Apices are reaching the lumina where the spermatozoa are attached to them. Nucleus are large, oval, pale & basally located. Cytoplasm :pale acidophilic containing lipid droplets. Function of Sertoli cells: 1-The lateral borders are bound together with tight junctions (blood testis barrier) - Barrier divides the tubules into luminal and basal parts that selects nutrients, hormones and minerals needed for growth and differentiation of spermatocytes to pass through this barrier. - It protects developing spermatocytes from foreign blood antigens and autoimmune response. 2-Phagocytosis of cytoplasm after spermiogenesis. 3-Secretion of a fructose rich medium (nourishes spermatozoa). 4-They secrete androgen – binding protein ( promotes the action of testosterone hormone). 5-Synthesis and secretion of inhibin (inhibits the release of FSH).  BLOOD TESTIS BARRIER Protect developing gametes from immune system. How ?  Spermatogenesis begins after puberty. So, the newly formed germ cells have a different chromosome number and different surface membrane receptors. So, consider foreign cells by immune system.  If no barrier an immune response would mounted against newly formed germ cells. MEDICAL APPLICATION  Failure of descent of the testes into the scrotum (cryptorchidism [Gr. kryptos, hidden, + orchis, testis]) maintains the testes at the core body temperature which inhibits spermatogenesis. Malnutrition, alcoholism, and the action of certain classes of drugs lead to alterations in spermatogonia, with a resulting decrease in production of spermatozoa. Immotile cilia syndrome in men is characterized by immotile spermatozoa and consequent infertility. This disorder usually coincides with chronic respiratory infections because of impaired motility of the ciliary axonemes of respiratory epithelial cells.  INTERSTITIAL CELL OF LEYDIG After puberty, appear in the C.T. between the seminiferous tubules. Are present singly or in groups. Are rounded or polygonal. Function:  Secrete testosterone hormone which is responsible for the development of the male secondary sexual characteristics at puberty.  Genital ducts 1. Intratesticular tubules: 1. Tubuli recti, 2. Rete testis and 3. Vasa efferentia 2. Extratesticular tubules: 1. Epididymis, 2. Vas deferens and 3. Ejaculatory ducts. Epididymis - Is lined with pseudostratified columnar ciliated epithelium and these cilia are immotile. - Its wall is formed of circular smooth muscles. - Its function is: 1. Absorption of testicular fluid, 2. Secretion of special proteins, 3. Phagocytosis of residual bodies and 4. It is the site of maturation of sperms  Vas Deferens - Opens into urethra by the ejaculatory duct. - Is formed of: 1. Mucosa: irregular, slightly folded and formed of pseudostratified columnar epithelium with stereocilia and corium of loose C.T. 2- Musculosa is a thick and dominant feature formed of three layers of smooth muscle, inner longitudinal, middle circular and outer longitudinal. 3-Adventitia: thin layer of loose connective tissue. Spermatic Cord - It is composed of: 1. Vas deferens. 2. Testicular artery and vein, nerve fibers. 3. Pampiniform plexus of veins. 4. Crermasteric muscle (involuntary& striated).  Seminal vesicles  Are two highly tortuous tubes.  The duct of each unites with terminal end of vas deferens to form ejaculatory duct.  It is formed of: 1. Mucosa is highly folded that lined by columnar or pseudostratified columnar epithelium. 2. Musculosa is formed of inner circular and outer longitudinal layers. 3. Adventitia is made of thin fibroelastic C. T. Secretions contain: fructose, other simple sugars, amino acids, ascorbic acids, prostaglandins.  Prostate - Is a single compound tubulo-acinar gland. - It is formed of:  Connective tissue stroma:capsule, trabeculae and reticular network.  Parenchyma: prostatic acini are lined by secretory epithelium of cuboidal, columnar or pseudostratified columnar ( depends on the activity of the gland). - The prostatic acini are distributed as follows :  Mucosal,  Submucosal  Main prostatic acini.  Prostatic concretions are calcified bodies of glycoprotein which are present in old age.  Secretions: citric acid, fibronalysin, serine protease (PSA). Clinical NOTE: if increased, can be early sign of prostatic cancer. One reason stems from the anatomical differences in the growth of prostate tissue. Benign neoplasm of the prostate grows in an area referred to as the transition zone of the prostate. Conversely, prostate cancer predominately grows in the central and peripheral zones of the prostate. Bulbourethral glands -Are tubulo-alveolar mucous glands which open into the beginning of urethra. - Its covering epithelium varies from simple cuboidal to simple columnar.  Its function is to lubricate the penile urethra.  Penis - Is covered by skin with no subcutaneous fat. - The erectile tissue is formed of: two dorsal corpora cavernosa and one ventral corpous spongiosum. - Each corpus is formed of blood spaces (vascular spaces). - It is surrounded by smooth muscle fibers and covered by a dense C.T., the tunica albuginea. - Cavernous (penile) urethra passes through the corpus spongiosum is lined with stratified columnar epith. - Glans penis is an enlargement at the terminal end of the penis and covered by a fold of skin. Clinical note: - Arterial or neural insufficiency to tissue of the penis can lead to erectile dysfunction which can be treated effectively in many cases with compounds like sildenafil, which enhance and prolong the effect of nitous oxide on the smooth muscle. Urethra - In males: it is formed of three regions : Prostatic part (lined by transitional epithelium). Membranous part (lined with pseudostratified columnar epithelium). Penile part (lined with stratified columnar and stratified squamous at its end). -In females: it is lined from inside outwards by transitional, pseudostratified columnar and stratified squamous at its external opening.