Structure and development of the telotrophic ovariole in ensign scale insects (Hemiptera, Coccomorpha: Ortheziidae)

The paired ovaries of young larva of the 3rd instar of Orthezia urticae are filled with numerous germ cell clusters that can be regarded as ovariole anlagen. Germ cells (cystocytes) belonging to one cluster form a rosette, in the centre of which a polyfusome occurs. Staining with rhodamine-phalloidin has revealed that polyfusomes contain numerous microfilaments. The number of cystocytes per cluster is not stable and varies considerably. The ovaries of older larva become elongated with numerous young ovarioles protruding into the body cavity. The ovarioles are not subdivided into the tropharium and vitellarium. In this stage germ cells differentiate into oocytes and trophocytes (nurse cells). The ovaries of adult females are composed of about 20 (Newsteadia floccosa) or 30 (O. urticae) ovarioles. Their trophic chambers contain trophocytes and arrested oocytes. In the vitellarium, at the given moment, only one oocyte develops. It has been observed that after maturation of the first egg the arrested oocytes may develop.