Ultrastructure of Mansonella ozzardi microfilaria, with a comparison of the South American (simuliid-transmitted) and the Caribbean (culicoid-transmitted) forms.

Ultrastructural studies conducted to elucidate and compare the microanatomy of the South American (simuliid-transmitted) and the Caribbean (culicoid-transmitted) microfilariae of Mansonella ozzardi revealed that these microfilariae are essentially identical. The only difference detected was the larger central body of the Colombian microfilariae. Although the microanatomy of M. ozzardi microfilaria is essentially the same as that of other microfilariae, some of the subtle differences noted between M. ozzardi and other microfilariae include: amphids of unequal lengths, a large nucleus located approximately 30 microns from the anterior end, and an esophagus which appears to be less developed than that of Loa loa and Brugia spp. The microfilaria has a small cephalic hook, intracellular bacteriae in the hypodermal cells, and crystalloid inclusions which are most prominent in the R-1 cell and are also present in the hypodermal and esophageal cells. These crystalloids appear to be unique to M. ozzardi microfilariae.