The embryonic development of the hemipteran insect Rhodnius prolixus was studied by use of contemporary light and electron microscopy. Embryos were staged according to days postoviposition. Eggs laid on day one complete blastoderm formation and anatrepsis, the first phase of blastokinesis, by day 5. The embryo develops in a cephalocaudal orientation which is 180° to the anteroposterior axis of the egg. Subsequent development, prior to the second phase of blastokinesis (katatrepsis), leads to segmentation of the germ band, evagination of appendages, and histogenesis of germ layers. Concomitantly with these events, the amnion undergoes dramatic change. By day 7 the embryo begins a 180° revolution while migrating to the ventral surface of the yolk. This restores its polarity with respect to that of the egg and facilitates hatching. The serosa contracts, pulling the amnion and embryo anteriorly. Eventually the serosa is internalized at a point dorsal to the head and the lateral walls of the embryo grow up and surround the yolk. Development continues until day 15 when the embryo hatches as a first instar larva.
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