Urinary and Reproductive System Histology

Urinary and Reproductive System Histology

Urinary and Reproductive System Histology

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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.
Tubule SegmentEpitheliumKey Feature(s)Primary Function(s)
Proximal Convoluted (PCT)Simple CuboidalProminent brush border (microvilli)Bulk reabsorption (glucose, amino acids, Na+, H₂O, HCO₃⁻)
Loop of Henle (LOH)Simple Squamous (thin limbs)-Urine concentration (countercurrent multiplier)
Distal Convoluted (DCT)Simple CuboidalMacula densa (part of Juxtaglomerular App.)Fine-tuning ions (Na+, K+, Ca²⁺); PTH action
Collecting Duct (CD)Simple CuboidalPrincipal cells; Intercalated cellsADH-regulated H₂O reabsorption; K⁺ & acid-base balance

Diagram of nephron and blood vessels

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:

      StructureEpitheliumKey Feature(s)
      EpididymisPseudostrat. columnar + stereociliaSperm maturation & storage
      Vas DeferensPseudostrat. columnarThick muscular wall (3 layers)
      Seminal VesiclesPseudostrat. columnarFructose-rich fluid, ~70% semen volume
      ProstateGlandular (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.

Ovarian Follicle Development Diagram

⭐ 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.

Practice Questions: Urinary and Reproductive System Histology

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Renin is secreted from which of the following?

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Flashcards: Urinary and Reproductive System Histology

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Which of the following parts of a nephron is lined by squamous epithelium?_____

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Which of the following parts of a nephron is lined by squamous epithelium?_____

Thin segment of loop of Henle

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