In eusocial bees, workers and queens are diploid (2n), whereas males are haploid (n). However, in some species, including the stingless bee Melipona quadrifasciata anthidioides Lepeletier, 1836, 2n males arise from fertilized eggs resulting from the crossing between a queen and her brother. In the present study, we provide a comparative analysis of the digestive and regenerative cells in n and 2n pupae and adult males of M. quadrifasciata anthidioides. In n and 2n pupae and adult males, the number of regenerative cells/nest was similar. In n and 2n pupae, the mean number of digestive cells/midgut area was 2076 ± 0.60, whereas in adults it was 1234 ± 1.42 digestive cells/midgut area. The nuclear area of the digestive cells was also similar in both n and 2n adult males (~154 µm²) and smaller in pupae (~91 µm²); this variation might be a result of DNA amplification in digestive cells during bee development. The results from our current study provide further understanding of the morphological and physiological aspects of the digestive tract of bees and show that the ploidy difference between n and 2n male stages does not affect the number of digestive and regenerative cells in the midgut of M. quadrifasciata anthidioides.

Os sistemas nervoso e endócrino controlam integra-damente os movimentos intestinais, a secreção de suas glândulas e também participam dos processos de digestão e absorção de nutrientes. Portanto, o objetivo central deste estudo foi verificar a existência de uma possível relação entre o número de células nervosas e gânglios dos plexos submucosos e mioentéricos e o número de células endócrinas no intestino delgado de adultos de D. aurita. As técnicas de coloração utilizadas foram Grimelius, Masson-Fontana modificada, imunoperoxidase direta e H-E. As células endócrinas argirófilas, argentafins e imunorreativas à insulina não variaram numericamente entre as regiões inicial, média e final do duodeno, jejuno e íleo (P>0,05), exceto as células argirófilas no jejuno (P<0,05). Nenhuma relação numérica foi verificada entre o número de gânglios nervosos e células endócrinas, e também entre células nervosas e endócrinas. Nós recomendamos o emprego de novas técnicas imunohistoquímicas para confirmar a correlação numérica entre os sistemas nervoso e endócrino no intestino delgado. A morfologia e a distribuição das células endócrinas e dos gânglios nervosos estudados foram similares àqueles encontrados em mamíferos eutérios.

The nervous and endocrine systems jointly control intestinal movements, secretions of their glands and also participate of the processes of nutrient digestion and absorption. Therefore, the central objective of this study was to verify the existence of a possible relationship between the number of nervous cells and ganglia of the submucosal and myenteric plexuses and the number of endocrine cells in the small intestine of adult D. aurita. The utilized staining techniques were Grimelius, modified Masson-Fontana, direct immunoperoxidase and H-E. Argyrophillic, argentaffin and insulin immunoreactive endocrine cells do not numerically vary between the initial, mid and final regions of the duodenum, jejunum and ileum (P>0.05), except for argyrophillic cells in the jejunum (P>0.05). No numerical relationship has yet been verified between the number of nerve ganglia and endocrine cells, and also between nervous and endocrine cells. We recommended the use of new immunohistochemical techniques to confirm the numerical correlation between the nervous and endocrine systems in the small intestine. The morphology and distribution of endocrine cells and the nerve ganglia studied were similar to those encountered in eutherian mammals.

Bees can form all levels of social organization, from solitary to advanced eusocial societies. Although 80% of the species exist as solitary species, most researches emphasize social species. This study focuses on the description of the male reproductive system of the solitary beesThygater analis (Lepeletier) and Melitoma segmentaria (Fabricius) and searches for traits that support behavioral and phylogenetic studies. The reproductive system of males were dissected, fixed in 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer pH 7.2 and post-fixed with 1% osmium tetroxide. The tissue was dissected and included for light microscopy. The species presented similar anatomical traits, including paired testicles, seminal vesicles, deferent ducts, accessory glands and an ejaculatory duct. Each testicle was composed of four follicles. In both species, a testicle and a seminal vesicle were surrounded by a joint capsule, forming a seminal vesicle-testicle complex. The two species presented accessory glands with very distinct morphological traits. The anatomic pattern and the histological traits of the reproductive system of the species studied were similar to those described for other bees. In addition, these traits can be used to differentiate species and allow inferences concerning their reproductive biology.