RESUMO
The male mucus gland is present in all species of bees, exception for meliponines. In bees, the function of themucus glands is not certain so far and its contribution to form the female espermatecal fluid is not assured.With the aim to contribute to the knowledge of the mucus gland in bees we carried out a histochemical studyof the gland in mature, adult males of Bombus morio, focusing on the histochemical nature of the secretion.The males were collected around the forest fragments into UFSCar, Campus Sorocaba. The glands werefixed and analysed under routine microscopy and for histochemistry techniques: Periodic Acid Schiff (PAS),Bromophenol Blue (BB), Sudan Black (SB) and Critical Electrolyte Concentration (CEC) variant. The resultsshowed that the mucus gland is constituted by a pair of large, thick tubular structures, which presented theirdistal portion more dilated and corn shaped. The glandular cells are columnar and in the apical portion presentseveral apocrine vesicles being released into the gland lumen. The histochemistry showed that gland secretionis very complex and contains protein (BB), neutral polysaccharide (PAS), as well as lipid (SB). The luminalgland secretion presents a background of homogenous content, presenting little dark dots stained by alltechniques used for this work. The investigation of the nucleolar activity (CEC) showed that the mucus glandepithelium is evolved in protein synthesis, presenting nucleoli developed and much RNA in the cytoplasm.