Ultrastructural features of the midgut of Rhinocricus padbergi (Diplopoda: spiroboida)

The midgut epithelium of the milipede Rhinocricus padbergi has been reported to be stratified or pseudostratified, and there is evidence that this region of the intestine is lined by a single layer of absorptive epithelial cells interspersed with smaller regenerative cells. In this work, transmission electron microscopy was used to study the structure and organization of the midgut of R. padbergi. The midgut was lined by a pseudostratified epithelium in which all of the cells were in contact with the basement membrane but did not necessarily reach the apical surface. The epithelium contained three cells types, namely, absorptive cells with apical microvilli that gave the midgut epithelium a "brush border" appearance, secretory cells that were interspersed with the absorptive cells and probably served to lubricate the epithelial surface, and regenerative cells located in the basal region of the epithelium. This organization of the gut cells in R. padbergi was similar to that of other arthropodes.

Ultrastructural features of the fat body and oenocytes of Rhinocricus padbergi Verhoeff (Diplopoda, Spirobolida)

The fat body of the diplopod Rhinocricus padbergi is located in two preferential areas of its body: a) immediately below the tegument, denominated parietal, and b) filling the body cavity, close to the viscera, mainly the ovaries and alimentary canal, denominated perivisceral. Ultrastructurally, its cells, the adipocytes, presented varied morphology and contained organelles indicating that they are cells that mainly produce and store lipids and proteins. The presence of cells similar to the oenocytes found in insects was observed for the first time in diplopods, associated to the fat body of R. padbergi. Our observations suggest that this tissue probably maintains activity cycles, since the presence of cells undergoing apoptosis was detected.