MORPHOLOGY AND FUNCTION OF INSECT FAT BODY CELLS: A REVIEW

Abstract

INTRODUCTION
The tissue that occupy the spaces among the insect organs, is generally named fat body and is compose by cells of mesodermal origin, sometimes containing, also, ectodermic cells. The mesodermal cells are the trophocytes and its derivates, and the ectodermal, the oenocytes. The proportion of the two cells in this tissue varies according to the phase of the life of the insect. During most of the life of the insect the cells of mesodermal origin, the trophocytes, are predominant and the oenocytes frequently are met disperse among them. In many cases the trophocytes acquire specialized functions and receive specific designations as: urocytes, chromatocytes or mycetocytes. The designation adipocyte is sometimes found in the literature for the main fat body cell. This name is improper since this cell is not a simple deposit of fat but have a much more complex metabolism and storage also proteins and sugars. The term trophocyte, indicative of nutrients storage cell is also restrictive in relation to their effective functions, because beyond the storage function it has others variable functions along the life of the insects, secreting substances for exportation, besides detoxification and excretory functions (KILBY, 1963; ISAC; BOWENS, 1982). The denomination adopted in this work is trophocyte, however, it should be pointed out that other cells receive from some authors the same denomination, as the nurse cells present in the insect meroistic ovaries.