File:Stage9 bf2-primordial germ cell region.jpg

Human Embryo (stage 9)

Carnegie Stage 9, week 3, day 20, somites 3-4

Ventrolateral view (cut away from chorion and amniotic sac) showing the embryo and yolk sac.

Green highlighted region shows the hind gut-yolk sac junctional region where primordial germ cells are thought to initially reside before migrating into the genital ridge.

Note also:

1. the relative size of the embryo and the associated extra-embryonic coeloms.
2. the shape of the early folded embryonic disc and rostro-caudal bendings.
3. the relative thicknesses of the embryo and extra-embryonic membranes.
4. the position of the prechordal plate (cardiogenic region) ventral to brain fold.

Page Links: Carnegie stage 9 | Week 3 | Primordial Germ Cell Development | Gastrulation

Carnegie Stages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | About Stages | Timeline

Image Source: Scanning electron micrographs of the Carnegie stages of the early human embryos are reproduced with the permission of Prof Kathy Sulik, from embryos collected by Dr. Vekemans and Tania Attié-Bitach. Images are for educational purposes only and cannot be reproduced electronically or in writing without permission.

Embryonic Development

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Original file name: Stage9day20somites3-4lateralbf2v2.jpg