Trophectoderm

In addition to Na+, K+-ATPase (see above), the Na+-independent GLUT2 glucose cotransporter is localized on trophectoderm basolateral membranes (Aghayan et al., 1992).

The embryo is mostly derived from the descendants of the inner cell mass, whereas the external cells, the trophoblasts or trophectoderm, produce no embryonic structures (Gardner 1983; Hogan et al. 1994).

In some cases, the fusion of the trophectoderms of two early embryos by the interaction of their cells inside the same zona pellucida can explain the fact that the two embryos share certain extraembryonic tissues.