Cytoarchitecture of the ovarioles in scale insects (Hemiptera, Coccinea)

Telotrophic ovarioles of scale insects are subdivided into tropharia (=trophic chambers) and vitellaria that contain single developing oocytes. Tropharium encloses trophocytes (=nurse cells) and arrested oocytes. The central area of the tropharium, termed the trophic core, is devoid of cells. Both trophocytes and oocytes are connected to the trophic core: trophocytes by cytoplasmic processes, oocytes by means of nutritive cords. The trophic core, processes and nutritive cords are filled with bundles of microtubules. The trophocytes contain large lobated nuclei with giant nucleoli. Fluorescent labelling with DAPI has shown that trophocyte nuclei are characterized by high contents of DNA. In the cortical cytoplasm of trophocytes, numerous microfilaments are present. The developing oocyte is surrounded by a simple follicular epithelium. The cortical cytoplasm of follicular cells contains numerous microtubules and microfilaments.