| Abstrakt: |
The epidermal cells, a derivative of ectoderm during embryogenesis of insects, contribute to the distinct cuticular pattern and form of the different stages that appear during their ontogeny. The type of cuticular products is the result of gene expression of the individual epidermal cells that lie immediately underneath these outgrowths (1). In hemimetabolous insects, the larval epidermal cells (LECs) present at the time of hatching from the egg and their descendants are responsible for the different cuticular patterns seen in the nymph and adult. In contrast, in many holometabolous insects, such as Drosophila, the distinct and different cuticular patterns exhibited by the larva and adult have a dual orgin; that of the larva is derived from the LEC and that of the adult is derived from the imaginal discs (2). The prospective integument of the adult head, thorax, genitalia, and analia is derived from imaginal discs (3-5). Each of the adult abdominal segments is derived mainly from three pairs of diploid histoblast nests (i.e., a pair of anterior dorsal [ADN], posterior dorsal [PDN] and ventral [VN] nests), located among the polytene LEC of the abdominal segments of the larva (see Fig. 1, Fig. 2 A-C, and 3 A,B). In addition, there is a pair of inconspicuous spiracular nests (SN) in each of the abdominal segments; during metamorphosis these nests (see Fig. 3 C) develop into the paired spiracles on the lateral sides of the adult abdominal segment (3,6-9). [ABSTRACT FROM AUTHOR] |
