Electron miscroscopy and histochemical studies on four Egyptian helminthes eggs of medical importance

By SEM the Fasciola gigantica egg is ovoid with a small knob like operculum, while the egg of Heterophyes heterophytes is broad oval with the operculum more tapering. The egg shell of fertilized Ascaris lumbricoides has interconnected ridges and peak-like projections, while the egg of Enterobius vermicularis is flattened with a thicker margin at the curved side. By TEM, Fasciola egg shell consists of fine reticulum fibrils of three layers. The outer lipoprotein of perivitelline membrane beneath which 2 membranes separated by inclusions, middle of protein globules and inner lipoprotein layer with minute electron-dense granules of melanin or polymer origin, in some parts of the shell giving the egg its brown coloration. The Heterophyes egg shell is more or less similar to that of Fasciola but lacking the minute electron-dense granules. The egg shell of Ascaris has outer ulterine layer with three consecutive layers, basal lipoprotein layer and the inner lipid or ascaroside layer which is the most resistant layer. The Enterobius egg shell consists of five layers, external uterine, internal uterine, vitelline, chitinous and lipid layer. Histochemically, Fasciola egg shell consists of nine amino-acids, and that of Heterophyes consists of ten amino acids. In Ascaris, the lipid layer characteristically consists 25% protein and 75% lipid. The histochemical examination of Enterobius as a detailed example, showed different degrees of reactions with mercuric bromophenol blue, diazotization coupling, Sakaguchi reaction, Sudan black and Mallory's triple stain. Temperature showed marked effect on eggs survival. Eggs of Fasciola and Heterophyes withstand more low temperatures but those of Ascaris and Enterobius withstand more high ones. There are marked correlations between the egg shell constitution, histochemical compositions on one hand and water permeability and egg dryness on the other hand. The results were photographed and discussed.