Embryology of the Gonads PDF
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This document, likely for a biology class, describes the embryological processes of gonadal development, including sexual differentiation and descent of the testes and ovaries. It covers the factors influencing these developments, like the presence of sex chromosomes and hormones.
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07/01/24 Embryology of the gonads: Learning objective: understand the process of sexual differentiation including chromosomal sex determination. Learning objective: describe the embryonic development of the ovary and the testes. Learning objective: appreciate the process of descent of the testes. Go...
07/01/24 Embryology of the gonads: Learning objective: understand the process of sexual differentiation including chromosomal sex determination. Learning objective: describe the embryonic development of the ovary and the testes. Learning objective: appreciate the process of descent of the testes. Gonads: Form in the intraembryonic coelom. Just the to show where intra embryoniccoelomis Sexual differentiation: XX ( female ) or XY ( male ). Gonadal differentiated determined by the presence or absence of testis determining region factor/ sex determining region on Y ( SRY ) chromosome. from the g testis Testosterone and antimullerian hormone: internal/external anatomy and gonad descent. develops Testosterone: brain sex. Derivation of the gonads: Gonads derive from 3 origins: Mesenchyme mesoderm of 1. coelom glining Mesothelium ( mesodermal epithelium ) lining the posterior abdominal wall. mesoderm a 2. Underlying mesenchyme ( embryonic connective tissue). 3. Primordial germ cells ( earliest undifferentiated sex cells which will become sperm or oocytes ). Gonads: 0-6 weeks, bipotential. They can become testes or ovaries. 6 weeks- gonadal ridge forms and germ cells. Sex determining region on Y: Testes: Walls of the seminiferous tubules composed of: Spermatogonia- the primordial sperm cells derived from primordial germ cells. Sertoli cells- which constitute most of the seminiferous epithelium in the foetal testes. Seminiferous tubules remain solid until puberty, when lumina begin to develop. Week 8- Leydig cells in bet ween the seminiferous tubules secrete testosterone. Testosterone production is stimulated by human chorionic gonadotropin. Sertoli cells in the tubules produced antimullerian hormone, which continues until puberty. Ovary: Slower development than testes. Primordial germ cells become primordial follicles consisting of am oogonium. The follicles are surrounded by a layer of follicular cells derived from the surface epithelium. Active mitosis produces many oogonia during fetal life. No oogonia form postnatally. Descent of the testes: same as lecture previous
