[Differentiation of oocytes and trophocytes in insect ovaries with different ovariole structures]

Early stages of differentiation of the oocytes and nurse cells are comparatively studied in the polytrophic ovarioles in larvae, pupae and imago of the butterfly Laspeyresia pomonella and in the telotrophic ovarioles in larvae and imago of the bug Eurigaster integriceps. In L. pomonella, the oocytes and trophocytes, being the descendants of one oogonial cell, pass synchroniously through early stages of meiotic prophase up to the pachyten. After the pachyten chromosomes of the future trophocytes transform into diakinetic bivalents, whereas in the oocyte nucleus chromosomes retain their pachyten stage appearance. In the fifth instar larva of E. integriceps, two zones may be seen in the germarium of the telotrophic ovariole: the apical trophocyte zone and the distal oocyte zone. The oocytes develop up to the zygotene("bouquet") stage. As to the future trophocytes, they miss zygotene and reach directly diakinesis. Thus,the earlier divergence in the development ways of oocytes and trophocytes is observed in the telotrophic ovarioles, since the trophocyeres pass themeiotic stages more quickly then oocytes. The supposition is advanced that the quicker development of the nurse cells in the bug's ovarioles takes place due to missing the synaptonemal complex formation. The patterns of similarity and distinction between the telotrophic ovarioles in Coleoptera, on the one hand, and the polytrophic ovarioles of the butterfly L. pomonella and telotrophic ovarioles of the bug E. integricept, on the other hand, are discussed.