Figure 7.2 Sea urchin S. purpuratus embryogenesis.
發(fā)布日期：2006-04-15 來(lái)源：- 作者：448 x 496 像素
核心提示：a) 60-cell embryo undergoing rapid cell division. Cell fates have
been determined for many of these cells as shown by the color
code for future ectoderm, mesoderm, and endoderm layers.
Cells not yet committed to one of the three layers appear whit
