Lecture on Spermatogenesis

Overview

The lecture covers the process of transforming a stem cell into a mature sperm.
Key terms: spermatogonia, spermatocytes, spermatids, spermatozoa, spermatogenesis, and spermogenesis.

Primordial Germ Cell (PGC): Originates the cells that produce sperm.
Bilaminar Disk & EPI Blasts: Involved in PGC migration to the yolk sac.
Migration: Around week 4-5, PGCs migrate to the genital ridge near T10 (thoracic region).
Development: Genital ridge differentiates into gonads; male development focuses on medullary sex cords.

Structure: Testes contain 250 lobules, each with 1-4 seminiferous tubules.
Development: Involves duct systems like the vas deferens.
Cell Types: Sertoli cells (support cells) and Leydig cells (located in interstitial areas).

Stages:
- Stem Cell: Replicates to maintain sperm production.
- Type A Spermatogonia: Divides into dark and pale types.
- Type B Spermatogonia: Prepares for meiosis.
- Primary Spermatocyte: Undergoes meiosis I to form secondary spermatocytes.
- Secondary Spermatocyte: Undergoes meiosis II to form spermatids.
Mature Sperm Formation (Spermiogenesis):
- Golgi Phase: Acrosome forms.
- Tail Formation: Flagella development.
- Mitochondria Concentration: Energy production.
- Release: Spermatozoa detach and are transported.

Hormonal Changes: FSH and LH influence sertoli and Leydig cells.
Sertoli Cell Function:
- Support and nourish developing sperm.
- Secrete hormones like inhibin and androgen-binding protein.
- Facilitate sperm transport.

The lecture detailed the full process from stem cell development in the embryo to the formation of mature sperm.
Highlighted the role of the seminiferous tubules, sertoli cells, and hormonal influences in spermatogenesis.