Egg development from oviposition to first hatching and release of a morula-like structure.

<p><b>A</b>. Egg of <i>A. ervi</i> in the first hours after oviposition. <b>B</b>. Cellularisation occurs after limited syncytial cleavages, cell membranes are visible through the chorion (arrows in B). <b>C</b>. Folding processes of serosa cells beneath the egg chorion. <b>D</b>. Chorion rupture and embryo emergence from the chorion in the host hemocoel within the 24 h after oviposition (first hatching). <b>E</b>. Morula-like structure, about 24 h after hatching in the blastocoels. It is formed by the primordium (<b>pr</b>) surrounded by a monolayer of large cells, serosa cells (<b>sc</b>) forming the serosa membrane (Scale bars 25 µm for all panels). Abbreviations: pr, primordium; sc, serosa cells.