At first glance, the individual microfilaria of different genera and species appear to look quite a bit alike. However, with careful attention to the appearance of size, nuclear column, anterior (headspace), posterior (tail), and sheath, a successful identification may be made. The next few pages will discuss the specific anatomical terms and differentiate species based on these attributes.
Numerous atlases and references are available in print and online. (Please refer to the References page at the close of this module for additional information.)
Morphologic examination of blood films (or skin snips) is the preferred method to obtain identification. Useful terminology as applicable to the microfilariae anatomy includes the following:
Anatomy of microfilaria (Seen in the 1919 classic drawing to the right.)
Anterior (A = near the head)
Cephalic space - headspace devoid of nuclei (at the end of the M = mouth cavity)
Posterior (T = tail)
Sheath (Sh)- membrane; the body may (or may not) be enveloped in the sheath
