Fat body cells or throphocytes of individuals during beginning of pupation (pre-pupae) of Apis mellifera were collected and studied by routine and cytochemical preparations for transmission electron microscopy (TEM). The results showed that the trophocytes present large reserves of lipids, proteins, and glycogen. Imidazole osmium treatment revealed that lipids are deposited as droplets in the cytoplasm and also within protein granules. Thiery's reaction showed the presence of glycogen inside protein granules. An acid phosphatase reaction was performed to verify the role of this enzyme in the mobilization of stored reserves during metamorphosis. Positive reaction for acid phosphatase was detected at larger protein granules, at the periphery of the large lipid droplets, and free in the cytoplasm. The contents of protein, lipid and glycogen are stored in the trophocytes at larval phase to be used during metamorphosis. The acid phosphatase present in the products stored might be responsible for their metabolization, while acid phosphatase free in cytoplasm might actuates in the trophocytes histolysis that occurs during metamorphosis for energy production.
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