Reference

Hinton, H. E.,ed. 1981. Biology of insect eggs. Vols. 1-3. Pergamon, Oxford.

Embryology

Just prior to fertilization, insect eggs are composed mostly of yolk and small islands of cytoplasm surrounding the female nucleus on one edge. When the egg is laid, the nucleus is usually in the metaphase of the first meiotic division, in which state it receives the sperm, one of which unites with the oocyte after meiosis is complete. The nucleus then migrates to the center of the egg and begins to divide mitotically. The resulting cells move to the periphery and form the blastoderm, or early embryo, which later lodges on one side of the egg. The germ layers and embryonic membranes soon develop, and determination of segmentation and the primary organs and tissues ensues. The appendages appear, and after a time, the perfect body of the first juvenile stage is complete. This stage takes different forms depending on the evolutionary level of the group. Fairly similar embryological steps are followed by other terrestrial arthropods (Johannsen and Butt 1941). A major exception are the springtails (Collembola), whose eggs undergo holoblastic cleavage.

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