[Cytology of egg maturation in the silkworm (Bombyx mori L.) in artificial parthenogenesis]

The orientation of bivalentss in the first meiotic metaphase was studied on the squash preparations and sections of eggs in Bombyx mori L., Antheraea pernyi Guèr and Carpocapsa pomonella L. The reduction fissure of bivalents separating the homologous chromosomes lies in the plane of spindle equator; the equation fissure separating the sister chromatids is parallel to the long spindle axis. Complicated rearrangements are observed in the nuclei of the silkworm eggs stimulated to ameiotic parthenogenesis by the high temperature dissociation of bivalents, full destruction of spindle, formation of a new spindle and metaphase plate. The latter includes univalent chromosomes involved in the equation division. As a result, two genetically identical pronuclei with the somatic set of chromosomes are formed.