Lipid transport through the enterocytes of larval Aeshna cyanea (Insecta, Odonata)

The larval enterocytes of A. cyanea absorb lipid after luminal lipolysis in morphologically invisible form by direct membrane transport, presumably molecular diffusion. The lipolytic products are utilized for resynthesis of di- and triglyceride which become visible in the form of lipid droplets in the groundplasm. The putative site of lipid synthesis is the apical ER which locally forms highly ordered complexes. Lipid transport occurs in the form of matrix lipid so that the enterocytes of dragonfly larvae resemble in this respect the lipid-secreting mammocytes rather than the lipid-absorbing mammalian enterocytes. Lipid release involves partial lipolysis and direct membrane transport, possibly including membrane delamination, again in contrast to exocytosis in mammalian enterocytes and apocrine extrusion in mammocytes, which are both indirect membrane transport mechanisms.