Male reproductive system

• Male Reproductive system


  Gonads - produce male germ cells<|>Penis - copulatory organ<|>Set of tubes and tubules which transmit the male germ cells from the testes to the penis
• Accessory glands


  • Seminal vesicle
  • Prostate gland
  • Bulbourethral glands
• Testes


  Compound-tubular glands lodged in the scrotum
• Scrotum


  Pendulous bag of skin with a thin wall, composed of skin, incomplete layer of smooth muscle (Dartos muscle), and subcutaneous tissue
• Testicular capsule layers


  • Tunica vaginalis - outer
  • Tunica albuginea - composed of dense fibrous tissue
  • Tunica vasculosa - contains a network of blood vessels
• Mediastinum testis


  Thickened portion of capsule on the posterior border of each testis
• Septuli testis


  Fibrous partitions that divide the testis into numerous pyramidal compartments, Testicular Lobules
• Seminiferous tubules


  Wall is made up of outer capsule of fibroelastic connective tissue, germinal or seminiferous epithelium, and thin basement membrane
• Lining epithelium of seminiferous tubules

  • Supporting cells (Sustentacular cells/ Sertoli cells)
  • Spermatogenic of Germ cells
• Sertoli cells


  Tall, columnar in shape, rest on basement membrane, cytoplasm has well developed SER, secretory function
• Functions of Sertoli Cells

  • Provide mechanical support and protection to the developing germ cells
  • Provide nutrition for the developing germ cells
  • Play an active role in the release of spermatozoa
  • Phagocytosis of cellular fragments
  • Formation of blood-testis permeability barrier
• Spermatogenic cells


  Form the bulk of the epithelium, give rise to mature spermatozoa by Spermatogenesis
• Spermatogenesis


  1. Spermatocytogenesis - Mitosis of spermatogonia to become spermatocytes

  2. Meiosis - Maturation-division of spermatocytes, chromosome number is reduced by half, produces spermatids

  3. Spermiogenesis - Spermatids are transformed into spermatozoa
• Spermatogonia


  Located beneath the basement membrane of the seminiferous tubules, contain a round, dark-staining nucleus
• Types of Spermatogonia


  • Type A Spermatogonia - Nucleus: oval, fine chromatin granules, Nucleolus: lie close to the nuclear membrane, Cytoplasm: pale staining, homogenous, undergo mitotic divisions
  • Type B Spermatogonia - Nucleus: spherical, coarse chromatin, Nucleolus: centrally located, Cytoplasm: dark-staining, give rise to Primary Spermatocytes
• Primary Spermatocytes


  Biggest of the spermatogenic cells, located at the peripheral, middle, or near the lumen, seen in various stages of prophase (mitotic prophase is prolonged), Nucleus: plenty of mitotic figures
• Secondary Spermatocytes


  Smaller than Primary Spermatocytes, Nucleus: homogenous, immediately undergo the second Meiotic division, transformed to Spermatids, carry a Haploid number of chromosomes
• Spermatids


  Spherical or polygonal, Nucleus: small, dark staining with fine granular chromatin, undergo Spermiogenesis, transformed into Mature Germ cells
• Spermatozoa


  Mature sperm cells, actively motile, consists of head and tail, quiescent in seminiferous tubules and ducts of the testis, become active by the secretion of the accessory glands, production begins at puberty, continuous throughout life, but diminishes with age
• Interstitial Cells of Leydig


  Large cells, Nucleus: pale, spherical, oval, acidophilic, found scattered between seminiferous tubules, secrete Testosterone
• Tubuli Recti


  Lined by Simple Cuboidal Epithelium
• Rete Testis


  Lined by Simple Cuboidal Epithelium
• Efferent Ductules


  Lined by alternating groups of tall columnar cells with cilia and low columnar cells without cilia
• Ductus Epididymis


  Highly convoluted tubule, storage of spermatozoa, where spermatozoa undergo final maturation steps required for their ability to fertilize an egg (motility, membrane receptors for zona pellucida proteins, maturation of the acrosome, ability to fertilize), lining epithelium is Pseudostratified Columnar cells with Stereocilia
• Cell types in Ductus Epididymis

  • Principal cells - Tall, columnar cells containing non-motile of long branching microvilli
  • Basal cells - Small, pyramidal cells lodges between the bases of the columnar cells
• Ductus (Vas) Deferens


  Mucosa is lined by Pseudostratified Columnar Epithelium with some stereocilia, thrown into several longitudinal folds, making the lumen narrow and with irregular outline, lamina propria is rich in elastic fiber, muscularis layer is the thickest, made up of inner longitudinal, middle circular, and outer longitudinal layers to propel the seminal fluid during ejaculation, tunica adventitia is loose, fibroelastic connective tissue that blends with the tissues of the spermatic cord
• Spermatic Cord


  Enters the inguinal canal, enclosed by the Cremaster muscle, consists of vas deferens, testicular artery, pampiniform plexus of veins, and autonomic nerves
• Ampulla of the Vas Deferens


  Wider lumen, mucosa is much more folded
• Ejaculatory Ducts


  Formed by the union of the Ampulla of the Vas Deferens and the Excretory ducts of the Seminal vesicle, opens into the Prostatic utricle, lined by Pseudostratified Columnar to Simple Columnar Epithelium
• Seminal Vesicle


  A pair of exocrine glands located behind the urinary bladder, secretes and stores a yellow, viscous, alkaline fluid which nourishes the sperm cells and forms part of the seminal fluid, contents include fructose, citrate, inositol, prostaglandins, fibrinogen, enzymes and other proteins
• Histological features of Seminal Vesicle

  • Mucosa forms a complicated series of primary folds which branch into secondary and tertiary folds, lining epithelium is Pseudostratified Columnar or Simple Columnar epithelium
  • Tunica muscularis has inner circular and outer longitudinal layers of smooth muscles
  • Tunica adventitia is dense collagenous tissue
• Prostate Gland


  Consist of 30-50 branched tubulo-alveolar gland, located below the urinary bladder and surrounding the first part of the urethra, surrounded by a fibroelastic capsule
• Zones of Prostate Gland

  • Transition zone - around the prostatic urethra, contains Mucosal glands
  • Intermediate central zone - contain Submucosal glands
  • Peripheral zone - outermost, largest layer, contain the most numerous Main glands
• Prostate Gland Alveoli


  Lined by Pseudostratified Columnar epithelium, secrete a thin, milky fluid, main source of Acid Phosphatase and Citric Acid of semen, fluid contains various glycoproteins and enzymes
• Bulbourethral (Cowper's) Glands


  Pair of small, compound tubulo-alveolar glands embedded in the urogenital diaphragm, secrete mucous which serves as a lubricant, ducts enter the membranous urethra, lined by Pseudostratified epithelium with enlarged alveoli having flattened cells and empty alveoli having cuboidal or columnar cells
• Penis


  3 cylindrical masses of Erectile Tissue - a pair of Corpora Cavernosa and an unpaired Corpus Spongiosum, the central portion of the corpus spongiosum is occupied by the Penile Urethra, the cavernous bodies are made up of Erectile Tissue consisting of anastomosing blood channels, penile erection occurs when blood flows into and fills the vascular channels
• Glans Penis


  Enlarged distal portion of the penis, forms a conical structure
• Tunica Albuginea


  Binds the 3 cavernous bodies together and forms a capsule around each one, hypodermis (external to the T. albuginea) is loose connective tissue that envelops the penis
• The skin that covers the penis has no hair follicle with limited sweat glands
• Glands of Tyson


  Sebaceous glands found on the undersurface of the prepuce, in uncircumcised penis, the secretion of this gland accumulates and forms a cheesy material called SMEGMA