Home›Glossary›YGlossaryyolkSubstance in an animal egg consisting of protein and fat that nourishes the developing embryo.Used in 112 species profilesAmatitlania nigrofasciataAncistrus ranunculusAncistrus sp.Ancistrus triradiatusAnomalochromis thomasiAphyocharax anisitsiAll 112 →