- reproductive system

Anatomy of Male Reproductive Tract

  • Primary Structures:

    • Testis: Site of sperm production and testosterone secretion.

    • Epididymis: Divided into Head (caput), Body (corpus), and Tail (cauda); sperm gain motility and are stored here.

    • Vas Deferens: Transports sperm from epididymis to ejaculatory duct.

  • Accessory Glands:

    • Seminal Vesicles: Produce alkaline fluid rich in fructose and prostaglandins.

    • Prostate Gland: Secretes slightly acidic fluid containing citrate and enzymes (e.g., PSA).

    • Bulbourethral Gland: Secretes mucus to neutralize acidic urine in urethra.

Key Testicular Cell Types

  • Sertoli Cells: "Nurse cells" that form the Blood-Testis Barrier (BTB) and provide nutritional support.

  • Leydig Cells: Located between tubules; secrete testosterone in response to LH.

Spermatogenesis

  • Spermatogonium (2n): Stem cells that undergo mitosis.

  • Primary Spermatocyte (2n): Enters Meiosis I.

  • Secondary Spermatocyte (n): Completes Meiosis II to produce spermatids.

  • Spermatids (n): Undergo spermiogenesis to become mature sperm.

  • Mature Sperm (n): Process takes approximately 64-72 days.

Structure of Spermatozoa

  • Head: Contains haploid nucleus.

    • Acrosome: Contains enzymes (hyaluronidase and acrosin) to penetrate the zona pellucida.

  • Midpiece: Packed with mitochondria that provide ATP.

  • Tail: 9+2 microtubule arrangement for propulsion.

Epididymis

  • Epithelium: Pseudostratified columnar with stereocilia.

  • Principal Cells: Secrete molecules for sperm maturation.

  • Basal Cells: Stem cells for the epithelium.

Anatomy of Female Reproductive Tract

  • Ovaries: Site of oogenesis and steroidogenesis (estrogen and progesterone).

  • Fallopian Tubes:

    • Fimbriae: Sweep oocyte into tube.

    • Ampulla: Most common site of fertilization.

  • Uterus Layers:

    • Myometrium: Smooth muscle; responsible for contractions during labor.

    • Endometrium: Inner lining.

      • Stratum Functionalis: Thickens and is shed during menstruation.

      • Stratum Basalis: Regenerates the functionalis.

Oogenesis and Follicular Development

  • Oogenesis Timing: Begins before birth (arrested in Prophase I), resumes at puberty; Meiosis II completed only if fertilization occurs.

  • Follicle Stages:

    • Primordial Follicle: Single layer of squamous granulosa cells.

    • Primary Follicle: Granulosa cells become cuboidal; Zona Pellucida forms.

    • Secondary Follicle: Fluid-filled spaces (antrum) appear.

    • Graafian Follicle: Mature follicle ready for ovulation.

  • Corpus Luteum: Forms after ovulation; secretes progesterone to maintain endometrium.

Endometrial Phases of Menstrual Cycle

  • Proliferative Phase: Driven by estrogen; regeneration of stratum functionalis.

  • Secretory Phase: Driven by progesterone; glands secrete glycogen-rich fluid.

  • Menstrual Phase: Triggered by progesterone withdrawal; tissue sloughing.

Cervix Histology

  • Endocervix: Simple columnar epithelium; secretes mucus.

  • Ectocervix: Stratified squamous epithelium.

  • Transformation Zone: Where two epithelial types meet; primary site for cervical cancer screening (Pap smears).