IMAGINAL DEVELOPMENT OF INTEGUMENT IN DESERT LOCUST, SCHISTOCERCA-GREGARIA-FORSK .4. STEPS IN MORPHOGENESIS OF GLANDULAR UNITS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 66  (3) , 145-161
Abstract
In the gregarious male S. gregaria Forsk., imaginal molting (mitosis, apolysis, new cuticle synthesis and ecdysis) is associated with the differentiation of numerous glandular units. These units, involved in sex pheromone secretion, are composed only of a basal glandular cell and an apical duct cell at that time. Each glandular unit originates from an isogenic group of cells of which the 4 elements (tetrad) are disposed on 2 levels. At each level a principal and an accessory cell may be recognized. The lower accessory, or ciliary cell, shows at apolysis a strong cytoplasmic protrusion and a typical ciliary formation. This formation associated with a diplosome goes through the duct cell and ends up in the exuvial space. It makes a inner mold; arranged around it are epicuticular materials, characteristic of the duct wall; then it disappears. The strong cytoplasmic protrusion retracts, allowing a glandular reservoir to form. A glandular cell may be recognized at an early stage owing to its RER [rough endoplasmic reticulum] development. The upper accessory cell strengthens the duct cell and secretes junctional cuticle between the duct and general cuticle. Accessory cells, after the imaginal molt, do not degenerate but acquire epithelial cell characteristics. The duct has a dual origin: the receptive part is secreted by the ciliary cell and the vector part by the duct cell. The organization and stages of morphogenesis of the glandular unit are discussed and compared to those of other apterygote or pterygote insects.

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