Accessory nuclei in the oocytes of the cockoo wasp, Chrysis ignita (Hymenoptera: Aculeata).

In the oocytes of Chrysis ignita, accessory nuclei (AN) arise before yolk formation, during advanced previtellogenesis. Two categories of AN, small (SAN) and large (LAN) can be distinguished at this stage of development. Both AN categories contain two dense, morphologically distinct inclusions (termed A and B) immersed in a translucent matrix. AN are exclusively located in the cortical (peripheral) ooplasm. Moreover, LAN are asymmetrically distributed also along the antero-posterior axis of the oocyte, and occur preferentially in the anterior pole periplasm. In contrast, the distribution of SAN is uniform throughout the periplasm.