Microscopy image of a PGA at day 8 showing the early tissues supporting the embryo, including the amniotic sac and the yolk sac-like structures, surrounded by (extra-embryonic) mesoderm tissue.

HeX-Embryoid model showing early blood cells (green) that have formed inside of blood vessels (red) surrounded by yolk sac mesoderm cells (blue) that support these tissues. University of Pittsburgh ...

In a longitudinal study published in Scientific Reports, researchers investigate the effect of maternal physical activity on the size and growth of the yolk sac during early pregnancy. To this end, ...

Researchers have developed a new stem cell model of the mature human amniotic sac, which replicates development of the tissues supporting the embryo from two to four weeks after fertilization. This is ...

Gastrulation, the process where an embryo reorganizes itself from a hollow sphere into a multilayered structure, is considered a 'black box' of human development. This is because human embryos are ...

In early pregnancy, the fetal pole is the first stage of embryonic growth visible on an ultrasound. Find out what it means when the fetal pole isn't visible. The fetal pole, which is also called an ...

What Is a Yolk Sac? A yolk sac is a small pouch made from thin membranes. The yolk sac is one of the first things to develop during pregnancy and one of the first things your healthcare provider will ...

These colorful embryonic squid are all feeding off yolk sacs within their eggs. Squid develop directly, which means that the embryos have the same basic body plan as an adult squid. Get a closer view ...

Amniotic fluid is a liquid that surrounds and protects your baby in the womb. When there’s too much amniotic fluid in your womb, though, that condition is called polyhydramnios. It can cause ...