Characterization of fat body cells at different developmental stages of Culex pipiens

The fat body, originates from mesoderm, has many metabolic functions which changes as the embryonic development of the insect progresses. It plays an important role in the intermediate metabolism and in the metabolism of proteins, lipids and carbohydrates. It has roles in synthesis, absorption and storage of nutrients from hemolymph. It is also responsible for the production of immunological system components, antibacterial compounds and blood clotting proteins. The most common type of fat body cells are trophocytes (the basic cells of the fat body) and oenocytes are found associated with the fat body. In this study, it is aimed at determining the cell types contained in the fat body of Culex pipiens at different developmental stages as well as identifying the molecules such as carbohydrate, protein and lipid contained in each of these cells. Knowing the regional distribution of the fat body cells and the concentration of its content at each developmental stage is important in understanding the process related to its physiology and it may help in fighting against the pest C. pipiens, which is a vector species for many contagious diseases observed in humans and other species. To achieve our goal, we have employed different histochemical techniques (fixatives and staining methods) for staining C. pipiens preparates of different developmental stages and analyzed the structure of the fat body, its distribution, its cell types and the macromolecular contents of the cells. We only observed trophocytes and oenocytes as fat body components in C. pipiens. The trophocytes had all the three macromolecules (lipids, proteins, carbohydrates) in the cytoplasm varying in concentration between the different regions and different stages. The oenocytes were observed below the integument as well as between the muscles in the larvae of Culex pipiens. They were present either as single cells or in clusters and also varied in size. Their cytoplasm was stained strongly for proteins when bromophenol blue staining was applied, but it was rather heterogeneous due to the lipid inclusions. On the contrary, oenocytes were not observed among the adult C. pipiens preparations.