黑斑蛙的减数分裂研究

本文研究了黑斑蛙的减数分裂,发现其性染色体所形成的性二价体主要呈末端与末端联接,浓缩期占79.6％,中期Ⅰ占75％,这进一步证明黑斑蛙确实存在XY型性别决定机制,这种XY型性染色体虽形态相同,但已发生了质的分化,可能是同型异质。黑斑蛙的性染色体并不形成性泡,少数二价体有中间交叉。

Studies in Meiosis of Rana nigromaculata

The sex chromosomes in Rana nigromaculaia belong to XX/XY type.The chromosome pair No.9 was probably the sex chromosomes that are homomorphic in morphology but exist heteromorphically in DNA replication pattern.How will the sex chromosomes of XX/XY type behave in meiosis? This article made a study on meiosis of Rana vigromaculata.We discovered that the sex bivalents were mainly end to end associated that were 79.6 per cent in diakinesis and were 75 per cent in first meiotic metaphase.This fact fully proved that sex chromosome in Rana nigromaculata indeed was XX/XY type; meanwhile it was demonstrated that the sex chromosomes of XX/XY type had differentiated in quality although the sex chromosomes of XX/XY type were homomorphic.They are probably homomorphic in morphology but they are probably variant in quality.Besides,the sex chromosomes in Rana nigromaculata did not form a sex vesicle in first meiotic prophase.A few diakinesis bivalents presented interstitial chiasmata.