Meiosis and early embryology of Blissus leucopterus hirtus montandon (heteroptera: Lygaeidae)

Abstract

At the time of oviposition, maturation is under way, and is completed after 2 hr of development. Early cleavage is synchronous, but the synchrony breaks down before blastoderm formation. Invasion of the peripheral cytoplasm by cleavage nuclei is accomplished between 12 and 18 hr of development. The embryonic rudiment forms on the ventral surface of the egg, and appears to be split and divergent anteriorly with the head lobes as lateral plates that are positioned over the surface of the yolk. Anatrepsis begins when the germ cells and the posterior end of the embryonic rudiment are drawn into the posterior end of the egg. This process, when completed, causes the embryo to be reversed in polarity. As anatrepsis ends, the inner layer is formed by the proliferation of cells from the germ band. Segmentation begins in the inner layer in the gnathal and thoracic areas. Segmentation of the ectoderm in the gnathal and thoracic areas is followed by segmentation in the abdomen. Soon, appendages appear, and the neuroblasts proliferate from the ectoderm in the thoracic region. Proliferation of neuroblasts in the abdomen occurs later.