Term Name:	parietal yolk sac
Synonyms:	primary yolk sac
Definition:	tissue that consists of two cellular layers (parietal endoderm and trophoblast) separated by a relatively thick nonvascular basement membrane (Reichert's membrane), and acts as a protective layer to supports and facilitates transport of nutrients between the uterine tissue and the yolk sac cavity.
Ontology:	Uberon Ontology [UBERON:0008853]