[Seasonal transformations in the lampbrush chromosomes and the morphogenesis of the karyosphere capsule in Rana temporaria oocytes detectable by an analysis of the isolated nuclear structures].

A study was made of the seasonal changes in lampbrush chromosomes, accompanying structures and the karyosphere capsule, isolated from diplotene oocytes of Rana temporaria of stages 3-6 of oogenesis, as classified by Dumont (1972). The frogs were collected from their hibernation sites. The formation of fibrillar material of the karyosphere capsule was followed from stage to stage. Isolation of nuclei by hand, and dispersal of their content was carried out as described by Callan (Callan, 1986; Callan et al., 1987). A modified Miller's method (Miller, Beatty, 1969) was used for the ultrastructural analysis. The examination of lampbrush chromosomes shows that they change from season to season (summer, autumn, winter), reaching the maximum size in summer (Fig. 2). In autumn their transcriptional activity decreases, although their size remains unchanged. In this period each transcription unit of lateral loops contains about IO RNP-fibrils per 1 mkm, whereas in summer their number is 20 per 1 mkm (Fig. 4, 5). A large number (about 100 per each bivalent) of spheroidal granules about 1.8 mkm in diameter appear around the autumn bivalent (Fig. 3). They constantly accompany the chromosomes and therefore are called satellites. In winter, the satellites are of variable diameter (0.8-5.3 mkm) and still bound to lateral loops of chromosomes. The loops are notably reduced, and the association of the satellites shortened, to aggregate into knots.(ABSTRACT TRUNCATED AT 250 WORDS)