Considerations on some cytological and ultrastructural observations on fat cells ofDaphnia(Crustacea, Cladocera)

Abstract
The fat cells of females of Daphnia obtusa have a well developed rough endoplasmic reticulum, free ribosomes and small Golgi complexes. When the ovaries contain growing parthenogenetic oocytes, the fat cells show few scattered glycogen granules, whereas they show abundant glycogen when the ovaries contain one vitellogenic amphigonic oocyte. The latter case could be explained by the fact that the fat cells synthesize little vitellogenin since the yolk of amphigonic oocytes is mostly endogenous.