title: Ultrastructural study of yolk formation in Porcellio scaber Latr. (Isopoda).
abstract: Two types of yolk are formed in the developing oocytes of a terrestrial crustacean, Porcellio scaber. The intra-oocytic yolk, arises through autosynthesis, and the extra-oocytic yolk, is derived from micropinocytosis. the so-called disc shaped bodies, which occur in large numbers within the cisternae of a branched system of endoplasmic reticulum, are precursors of the intra-oocytic uolk. Dictyosomes are not involved in yolk formation in this species. Thus, the vitellogenesis of Porcellio scaber occurs in a manner analogues to that described in the aquatic crustaceans, which indicates that environmental factors have relatively little effect on this process.
mesh_terms: D000818:Animals; D003445:Crustacea / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D004530:Egg Yolk; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005260:Female; D008854:Microscopy, Electron; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D009866:Oogenesis; D009940:Organoids / Q000648:ultrastructure; D010063:Ovum / Q000502:physiology*