Scanning electron microscopy of the scabies burrow and its contents, with special reference to the Sarcoptes scabiei egg.

An entire burrow of a female Sarcoptes scabiei (var. hominis) mite was examined by scanning electron microscopy during serial transverse sectioning. The elevated roof and the wall were composed of compacted corneocytes. The floor had a smooth surface except at the anterior end. Here it was made up of nucleated stratum granulosum cells, etched in appearance, presumably having been chewed by the mite. The female mite, the larvae, scybala, and eggs were also examined. The ultrastructure of the eggshell surface revealed it to have a distinctive geometric patterning. Cross-sectioning showed this shell or chorion to be composed of an outer layer of minute, closely packed penta- and hexahedrons resting on a thin inner homogenous layer. The polyhedric surface pattern was exactly replicated in the cement substance which attached the egg to the burrow floor. Observations were made on the embryonic positioning which permitted the larvae to emerge from the eggshells in a uniform manner.