Origin of yolk granules and their development in the snail, Physa acuta.
D000818:Animals; D003461:Crystallography; D003594:Cytoplasmic Granules / Q000648:ultrastructure*; D005260:Female; D006056:Golgi Apparatus / Q000502:physiology; D008854:Microscopy, Electron; D008954:Models, Biological; D010063:Ovum / Q000648:ultrastructure*; D012908:Snails / Q000648:ultrastructure*