Microfilaria of Mansonella streptocerca fixed in 2% formalin and stained with hematoxylin. Microfilariae of M. streptocerca are unsheathed and measure 180 to 240 micrometers. The tail is been into a hook-like shape, and the nuclei extend to the end of the tail. Microfilariae are found in skin and do not circulate in the blood.