MALE

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• MALE
• REPRODUCTIVE SYSTEM

Annabell C. Segarra, Ph.D.
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TESTES

• Extraabdominal location
• Can be divided functionally into
• Seminiferous tubules gamete production
• Interstitium synthesis of hormones

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Seminiferous tubules

• Coiled mass of loops which begin and end at the
  tubulus rectus.
• Compose the bulk of the testes
• There are about 250 tubules per testes
• They contain the germ cells and Sertoli cells

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Germ cells

• At puberty the quiescent gonocytes give rise to
  spermatogonia
• Spermatogonia undergo incomplete cytokinesis
• Spermatogonia spermatocytes
• spermatids sperm
• Spermatogenic activity is cyclical.
• In humans, spermatogenesis takes about 65 days

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Sertoli cells

• Line the basement membrane of the tubule.
• Bipolar cells rich in Golgi elements (secretion).
• They form tight junctions among themselves.
• They contain receptors for FSH and testosterone.

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Sertoli cells functions

• Their function is similar to the nurse cells or
  follicular cells in the female provide
  nourishment and protection to the germ cells.

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Sertoli cells functions

• Blood testis barrier
• Formed by tight junctions between adjacent
  Sertoli cells during puberty.
• It separates the tubule into two compartments
• Exterior (basal) - Spermatogonia
• Interior (adluminal) - Remaining spermatocytes
  and spermatids
• As a result, luminal fluid composition is
  different from interstitial fluid.

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Sertoli cells functions

• Blood testis barrier
• Prevents the body from recognizing haploid cells
  as non-self.
• Regulates movement of peptide hormones (inhibin
  and gonadotropins).
• Provides a low resistance pathway for electrical
  coupling between cells.
• Maintenance of an ionic and molecular gradient.
• Promotes meiosis

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Sertoli cells functions

• Secretion of tubular fluid
• Assists in the movement of sperm from tubules to
  epididymus.
• Provides gametes with necessary substances such
  as metal binding proteins, plasminogen activators
  and growth factors.
• Regulated by FSH

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Sertoli cells functions

• Synthesis of Androgen Binding Protein
• ABP binds testosterone and DHT
• It increases androgen concentration in the tubule
  and avoids fluctuations in androgen
  concentration.
• It is the main carrier of androgens to the
  epididymus.

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Sertoli cells functions

• Secretion of hormones
• Estrogen (immature rats)
• Mullerian inhibiting hormone (MIH)
• Secreted during fetal and early neonatal life
• Synthesis of inhibin
• Regulates FSH secretion
• It is essential for initial maturation of
  spermatids during puberty.

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Sertoli cells functions

• Germ cell movement
• Movement of germ cells from basement membrane to
  lumen.
• Phagocytosis
• Damaged germ cells and residual cytoplasm.
• Nutrition
• Synchronization between Leydig cell and tubule
  secretion.

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Hormonal regulation of Sertoli cells

• FSH
• Sertoli cells contain many FSH receptors.
• FSH increases protein synthesis (ABP, aromatase,
  inhibin), regulates lipid metabolism, stimulates
  glucose uptake and lactase production, increases
  cell surface glycoproteins, increases Sertoli
  proliferation during fetal and neonatal life.
• Its effects are mediated via cAMP

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Hormonal regulation of Sertoli cells

• Insulin
• Stimulates secretion of ABP and transferrin
• Glucagon
• Increases aromatization of testosterone
• Androgen
• Stimulates secretion of ABP in immature rats

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Leydig cells

• Also known as interstitial cells because of their
  location
• Usually located surrounding blood vessels
• They contain LH but not FSH receptors
• They are the main source of androgens
• They secrete 20 of estrogens
• Fetal Leydig cells degenerate shortly after
  birth adult Leydig cells redifferentiate from
  connective tissue during puberty.

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Leydig cells

• Synthesis of testosterone
• It is the main steroid secreted by Leydig cells.
• Synthesis occurs in the mitocondria and smooth ER
• It is stimulated by LH and hCG

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Peritubular myoid cells

• They surround the seminiferous tubules
  externally.
• They secrete regulatory factors
• May assist sperm transport into epididymus by
  inducing contraction of semiferous tubules.
• Testosterone stimulates proliferation and
  differentiation of these cells.

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Male accessory glands

• Seminal vesicle
• Secretes about 60 of the semen.
• Secretion is yellowish, viscous and alkaline.
• It is the main contributor of prostaglandins,
  coagulating factors, and fructose.
• Prostate
• Secretes about one third of the semen.
• Secretion is milky, usually acidic (pH 6.5).
• Contains enzymes necessary for sperm activation
  and provides polyamines such as spermine.

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Male accessory glands

• Bulbourethral glands (Cowper)
• Secretes a mucous solution involved mainly in
  lubrication and to neutralize the acidic pH of
  the urethra.