Premium
Growth and maturation in the parthenogenetic and sexual eggs of Moina macrocopa
Author(s) -
Allen Ezra,
Banta A. M.
Publication year - 1929
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1050480106
Subject(s) - biology , parthenogenesis , germinal vesicle , ploidy , prophase , meiosis , zoology , nucleolus organizer region , metaphase , microbiology and biotechnology , chromosome , genetics , embryo , nucleolus , cytoplasm , gene
From a study of over 1000 mothers, the female chromosome number appears to be 2N = 22; N = 11. The male number has not been exactly determined, but is presumably not haploid. Only one maturation division occurs in the parthenogenetic egg, and the authors have seen only one in the sexual egg. During the growth stages of the eggs, the chromatin is totally obscured by a large amount of deeply staining nucleolar material which exhibits several phases. Ultimately, this material is apparently absorbed into the ooplasm. Just before the egg is laid, the ovoid chromosomes, in late prophase or in metaphase, are seen in a germinal vesicle situated always at one side of the egg. The maturation division occurs immediately after egg laying. A degenerate body, hitherto undescribed, is noted in the ripe parthenogenetic egg, situated at the pole opposite the germinal vesicle. It is believed to arise by reorganization of nucleolar substance. The body in the sexual egg desribed by Weismann and Ishikawa ('91) as the Paracopulationzelle is noted and its interpretation by these authors questioned, but, for lack of sufficient evidence, no counter‐explanation is offered. The possible relation between experimental sex control and the time of maturation division in the parathenogenetic egg is discussed.