Amnion



Amnion (Greek amnos = lamb, amnion = "sheep's membrane") is the internal fetal envelope delimiting the cavity filled with amniotic fluid. It consists of ectoderm and  extraembryonic mesoderm (extraembryonic mesoderm subsequently differentiates into mesenchyme and the latter into the fibrous layer). By enlarging the amniotic cavity, the amnion envelopes the germinal shaft and ductus omphaloentericus, connects them together and helps the primitive umbilical cord to form. In the third of its development (end of the third month), it fuses with the chorion and forms a chorioamnion.

Related articles

 * Placenta
 * The first week of embryo development
 * Portal: Embryological preparations
 * Prenatal period
 * Embryonic envelopes and placenta

External references

 * Amnion (english wikipedia)