A stem-cell derived human embryo model showing blue cells (embryo), yellow cells (yolk sac) and pink cells (placenta). Scientists have grown an entity that closely resembles an early human embryo ...

The periphery of the disc spreads out over the yolk to eventually cover it, forming the yolk sac. Yolk sac is then infiltrated with a system of blood vessels, carrying nutrients from the yolk back to ...

This tissue forms sex cords which will develop into testes if the bird becomes a male or into the ovary if the bird becomes a female. Several thousand cells near the base of the yolk sac become very ...

Lipid utilization from the yolk sac plays a crucial role in embryonic development. Here, Chen et al. generate hsd17b12a mutant zebrafish and discover that a docosahexaenoic acid (DHA)-phosphatidic ...

The Seaside Aquarium has an intriguing dilemma going on in one of its tanks. “Not a skate egg casing this time, folks! This is a swell shark egg casing,” the aquarium posted on Facebook. “When ...