THE EMBRYOLOGY OF LYTTA VIRIDANA LE CONTE (COLEOPTERA: MELOIDAE): I. MATURATION, FERTILIZATION, AND CLEAVAGE

Abstract

This paper describes the embryonic development of Lytta viridana from oviposition to the formation of the blastema. The egg has the features commonly found in an insect egg. Bilateral symmetry is shown by the shape of the egg, variation in thickness of the vitelline membrane, and distribution of the yolk components. In the newly laid egg the vitelline membrane is porous. This is believed to be the first record of this phenomenon in insects. During cell division chromatin elimination occurs along the spindle to the equatorial plane. It is especially marked in the first meiotic division, but continues into late cleavage. During the first 4 hours the periplasm flows first forward to the cephalic region and then caudad along the central axis. The belief is expressed that this movement is associated with the prefusion movements of the sperm and fertilization. Fertilization occurs at about 3 hours. During the first 14 hours of development, marked morphogenetic movements of the deutoplasm occur.