Ultrastructure of the midgut endocrine cells in Melipona quadrifasciata anthidioides (Hymenoptera, Apidae)

Abstract

In this study we describe the ultrastructure of the endocrine cells observed in the midgut of M. quadrifasciata anthidioides. This bee has two types of endocrine cells, which are numerous on the posterior midgut region. Cells of the closed type are smaller and have irregular secretory granules with lower electrondensity than those of the open cell type. The open cell type has elongated mitochondria mainly on the basal area, where most of the secretory granules are also found. Besides the secretion granules and mitochondria, endocrine cells in this species have well-developed autophagic vacuoles and Golgi complex elements.Key words: insect midgut, endocrine cells, ultrastructure, secretory granules, stingless bee. RESUMO Ultra-estrutura das células enteroendócrinas do intestino médio deMelipona quadrifasciata anthidioides (Hymenoptera, Apidae)Neste estudo descrevemos a ultra-estrutura das células enteroendócrinas observadas no intestino médio de M. quadrifasciata anthidioides, abelha na qual ocorrem dois tipos de células enteroendócrinas, concentradas na região posterior do intestino médio. As células do tipo fechado são menores e possuem grânulos de secreção menos eletrodensos e menos regulares do que as células do tipo aberto. As células do tipo aberto possuem ainda longas mitocôndrias concentradas principalmente na região basal, onde também se concentra a maior parte dos grânulos de secreção. Além dos grânulos de secreção e das mitocôndrias, as células endócrinas nessa espécie possuem grandes vacúolos autofágicos e elementos do complexo de Golgi bem desenvolvidos.Palavras-chave: intestino médio, células enteroendócrinas, ultra-estrutura, grânulos de secreção, abelhas sem ferrão.

Mitochondria in the midgut epithelial cells of sugarcane borer parasitized by Cotesia flavipes (Cameron, 1891)

“…Few works show the morphology of endocrine cells, but some of them present different endocrine cell types along the insect midgut, with regard to the form, localisation and morphology, besides electron-density of granules. In this manner ten types were described in Aeshna cyanea (Müller, 1764) (Odonata, Anisoptera) (Andries, 1976), six types in Periplaneta americana (Linnaeus, 1758) (Dictyoptera, Blattidae) (Nishiitsutsuji-Uwo and Endo, 1981) and two types in Melipona quadrifasciata anthidioides Lepeletier, 1836 (Hymenoptera, Apidae) (Neves et al, 2003). The variability of mitochondria observed in cells visualised along the midgut of D. saccharalis larvae may be related to the pres- ence of different endocrine cell types that could not be identified due to a reduced number of these cells in midgut epithelium, as already described in other species of insects (Montuenga et al, 1989).…”

Serotype Differences and Lack of Biofilm Formation Characterize Yersinia pseudotuberculosis Infection of the Xenopsylla cheopis Flea Vector of Yersinia pestis

“…In contrast, the cuticle lining of the flea proventriculus is composed primarily of chitin filaments embedded in a complex, highly sclerotized protein matrix (19,28). The nature of this protein matrix has not been determined for fleas, but the cuticle lining the proventriculus of bees contains abundant cysteine-rich proteins that confer an overall acidic character (32).…”

Midgut epithelial endocrine cells are a rich source of the neuropeptides APSGFLGMRamide (Cancer borealis tachykinin-related peptide Ia) and GYRKPPFNGSIFamide (Gly1-SIFamide) in the crabs Cancer borealis, Cancer magister and Cancer productus

“…In C. magister, as well as in the lobsters Homarus americanus and Homarus gammarus, the putative endocrine cells were identified throughout the midgut proper, as well as in its associated caeca (Mykles, 1979). In terms of their ultrastructure, these cells were found to be essentially identical to their insect counterparts (Reinhardt, 1976;Hecker, 1977;Endo and Nishiitsutsuji-Uwo, 1982;Brown et al, 1985;Leite and Evangelista, 2001;Neves et al, 2003). Specifically, in C. magister they exhibited a slightly enlarged basal region, which contains the nucleus, an extensive rough endoplasmic reticulum and Golgi complex, as well as a A. E. Christie and others slender apical extension that projects toward the midgut lumen (Mykles, 1979).…”