The human body louse egg--correlative study of anatomy by SEM and light microscopy

SEM and correlative light microscopy of the developing egg of the human body louse reveals a complicated aeropyle system within the operculum important for gaseous exchange. With SEM the opened nit shows three new structures: one, latch-like; a second, ellipsoid with spikes; and a third, pad-like with two parallel rows of pores. They are part of the surface membranes covering the developing embryo. The relationship of the pad-like structure to the ellipsoid structure with spikes is seen by tilting the specimen. The light microscopy findings help to understand the relationship of these structures, which to separate at the time of hatching. A theoretical model is proposed for the hatching mechanism. The latch consists of a clasp on a stalk which may act as a hinged lock when the operculum opens outward. The ellipsoid with spikes and pad appears to separate when the vitelline membrane is ruptured at the time of hatching.