title: B lymphopoiesis in mammalian ontogeny: earliest sites of B lymphopoiesis and microenvironmental factors.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002454:Cell Differentiation; D004622:Embryo, Mammalian / Q000276:immunology*; D005260:Female; D008099:Liver / Q000196:embryology; D051379:Mice; D011247:Pregnancy