Department of Biology
Higley Hall
Kenyon College
Gambier, Ohio 43022
740-427-5383
"It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life."
Lewis Wolpert (1986)
During gastrulation, cell movements result in a massive reorganization of the embryo from a simple spherical ball of cells, the blastula, into a multi-layered organism. During gastrulation, many of the cells at or near the surface of the embryo move to a new, more interior location.
The primary germ layers (endoderm, mesoderm, and ectoderm) are formed and organized in their proper locations during gastrulation. Endoderm, the most internal germ layer, forms the lining of the gut and other internal organs. Ectoderm, the most exterior germ layer, forms skin, brain, the nervous system, and other external tissues. Mesoderm, the the middle germ layer, forms muscle, the skeletal system, and the circulatory system.
The primary germ layers (endoderm, mesoderm, and ectoderm) are formed and organized in their proper locations during gastrulation. Endoderm, the most internal germ layer, forms the lining of the gut and other internal organs. Ectoderm, the most exterior germ layer, forms skin, brain, the nervous system, and other external tissues. Mesoderm, the the middle germ layer, forms muscle, the skeletal system, and the circulatory system.
This fate map diagram of a Xenopus blastula shows cells whose fate is to become ectoderm in blue and green, cells whose fate is to become mesoderm in red, and cells whose fate is to become endoderm in yellow. Notice that the cells that will become endoderm are NOT internal!
Read more at http://biology.kenyon.edu/courses/biol114/Chap14/Chapter_14.html
