Urinary and Reproductive System Histology

Kidney Histology - Bean Scene Investigation

• Glomerulus: Site of blood filtration.
  • Filtration Barrier: Composed of:
    • Fenestrated capillary endothelium.
    • Glomerular Basement Membrane (GBM).
    • Podocyte foot processes with slit diaphragms.
  • Key Cells:
    • Podocytes: Visceral epithelial cells.
    • Mesangial cells: Intraglomerular; provide structural support, phagocytosis, and regulate GFR.

Lower Urinary Tract & Male Genital System - Pipes & Procreation

• Lower Urinary Tract (LUT):
  • Ureter, Bladder, Urethra: Lined by transitional epithelium (urothelium); muscularis externa for peristalsis/expulsion.
• Male Genital System:

  • Testis:

    • Seminiferous tubules: Site of spermatogenesis.
    • Sertoli cells: Support, form blood-testis barrier, secrete Androgen Binding Protein (ABP), Inhibin.
    • Leydig cells (interstitial): Produce testosterone.

  • Duct System & Glands Table:

    Structure	Epithelium	Key Feature(s)
    Epididymis	Pseudostrat. columnar + stereocilia	Sperm maturation & storage
    Vas Deferens	Pseudostrat. columnar	Thick muscular wall (3 layers)
    Seminal Vesicles	Pseudostrat. columnar	Fructose-rich fluid, ~70% semen volume
    Prostate	Glandular (variable)	Corpora amylacea, PSA, fibrinolysin

  • 📌 Mnemonic (Sperm Path): SEVEN UP (Seminiferous tubules, Epididymis, Vas deferens, Ejaculatory duct, Nothing, Urethra, Penis).

⭐ Exam Favourite: Sertoli cells form the blood-testis barrier and produce Androgen Binding Protein (ABP).

Ovary & Uterine Histology - Femme Histo Focus

• Ovary:
  • Follicular Development:
    • Primordial: Oocyte, single layer squamous follicular cells.
    • Primary: Cuboidal granulosa cells, zona pellucida (ZP). Theca folliculi begins.
    • Secondary (Antral): Antrum forms; stratified granulosa. Theca interna (steroidogenic) & externa.
    • Graafian: Large antrum, cumulus oophorus, corona radiata.
  • Corpus Luteum: Post-ovulation; Granulosa lutein (progesterone), Theca lutein (estrogen).
  • Corpus Albicans: Regressed CL; fibrous scar.

• Uterine Tube (Salpinx):
  • Mucosa: Ciliated columnar cells (transport); Peg cells (secretory, nutritive).
• Uterus:
  • Endometrium:
    • Stratum Basalis: Deep, regenerative.
    • Stratum Functionalis: Superficial, sheds. Cyclical changes:
      • Proliferative (Estrogen): Straight glands. Thickness ~2-5 mm.
      • Secretory (Progesterone): Coiled, "saw-tooth" glands. Thickness ~10-14 mm.
      • Menstrual: Functionalis shed.
  • Myometrium: Smooth muscle.

⭐ The corpus luteum is crucial for progesterone secretion, maintaining early pregnancy.

Cervix, Vagina & Placenta - Final Femme Frontier

• Cervix: Connects uterus to vagina.
  • Endocervix: Simple columnar epithelium (mucus-secreting).
  • Ectocervix: Stratified squamous non-keratinized epithelium.
  • Transformation Zone (TZ): Junction of endo- and ectocervix; squamous metaplasia site.

    ⭐ The transformation zone of the cervix is the most common site for development of cervical intraepithelial neoplasia (CIN) and cancer.

• Vagina: Elastic, muscular tube.
  • Epithelium: Stratified squamous non-keratinized, rich in glycogen (estrogen-stimulated).
  • Glycogen → lactic acid (Döderlein bacilli) → acidic pH. No glands.
• Placenta: Fetal-maternal exchange organ.
  • Chorionic Villi: Functional units.
    • Layers:
      • Syncytiotrophoblast (outer): Multinucleated; produces hCG, hPL.
      • Cytotrophoblast (inner): Mononucleated, mitotically active progenitors.
    • Stroma: Contains Hofbauer cells (macrophages) and fetal capillaries.

High‑Yield Points - ⚡ Biggest Takeaways

• Podocytes with foot processes and filtration slits are crucial for glomerular filtration.
• Juxtaglomerular apparatus (JGA), with macula densa and JG cells (renin), regulates BP and GFR.
• Proximal Convoluted Tubule (PCT) is characterized by a brush border for extensive reabsorption.
• Transitional epithelium (urothelium) lines the urinary bladder and ureters, allowing for distension.
• Sertoli cells in seminiferous tubules support spermatogenesis and form the blood-testis barrier.
• Leydig cells, found in the testicular interstitium, are responsible for testosterone production.
• The corpus luteum in the ovary secretes progesterone and estrogen post-ovulation.