Home›Glossary›YGlossaryyolkEdit this pageSubstance in an animal egg consisting of protein and fat that nourishes the developing embryo.Used in 114 species profilesAmatitlania nigrofasciataAncistrus ranunculusAncistrus sp.Ancistrus triradiatusAnomalochromis thomasiAphyocharax anisitsiAll 114 →