Figure 4.

Photomicrographs of the cuticle of female Onchocerca volvulus and Dracunculus medinensis. A, Portion of female Onchocerca volvulus worm removed from case seen in Figure 1. The nature of the cuticle, especially the external ridges and underlying striae, are clearly evident, including one stria under each ridge and one stria between adjacent ridges. Scale bar = 25 μm. B, Portion of D. medinensis female cuticle showing the four-fold greater thickness, and smooth surface devoid of external ridges or internal striae. Scale bar = 50 μm. This figure appears in color at www.ajtmh.org.