A comparative study of fat body at different developmental stages in Bombyx mori (L.): Histological and ultrastructural aspects

The fat body, originating from mesodermal tissue of coelomic cavities during embryogenesis, can be found throughout the insect's body. In some insects, the fat body has two types (peripheral and perivisceral fat bodies) according to its location. In the fat body, trophocytes are known to be the basic cell type. Other fat body cells differentiating from the trophocytes are urocytes, mycetocytes, chromatocytes and haemoglobin cells. The study aimed to demonstrate the general structure and cell types of the fat body during the postembryonic developmental stages of Bombyx mori (L.). With Haematoxylin–Eosin staining, there is a single type of fat body throughout the larval stages but during Pp and P0 stages it consists of perivisceral and peripheral fat bodies. We also observed that the compact structure of the fat body at the beginning of the larval stage began to loosen as it transformed into the pupal stage. In the adult stage, it was reorganized during the metamorphosis and it didn't show both fat bodies distinction. At this stage, the fat body appeared in a loose, lace‐like structure. We determined that B. mori fat body only consists of trophocytes and also among them; the fat body associated cells, oenocytes are detected.