Fine structure of the fat body of the female of Calliphora erythrocephala during the first egg-maturation cycle.

Abstract

During the first egg-maturation period (6 days at 25° C) the adult fat body of the female of Calliphora goes through sequential changes correlated with the development of the oocytes. The first two days represent a growth and differentiation phase. Free ribosomes and rough endoplasmic reticulum (RER) gradually increase in quantity. Golgi complexes consisting of clusters of vesicles and vacuoles appear to bud off from cisternae of the RER. Dense bodies possibly arise by sequestration from Golgi complexes. Content of acid phosphatase shows the dense bodies to be lysosomes. Many contain crystalloids. Glycogen is first seen as a network, in which gamma-elements appear; later alpha-particles occur. Lipid droplets are abundant. Lipid droplets break down where they border upon glycogen. In four-day old females the fat body is in a phase of production. Golgi complexes concentrate protein secretion granules believed to represent yolk protein. Then follows a phase of regression characterized by the formation of cytosegresomes and by an accumulation of lipid. In mature females a remodeling of the fat cell begins, evidenced by a renewed formation of free ribosomes, RER, and probably dense bodies resembling those of the one-day old female.