小麂、黑麂、赤麂精母细胞联会复合体的比较研究

本工作以界面铺张——硝酸银染色技术,对小麂(Muntiacus reeuesi)、黑麂(M.crinifrons)和赤麂(M.muntjak)的精母细胞联会复合体(Syna ptonemal complex,SC)进行亚显微结构的比较研究。结果表明: 1.SC的平均相对长度和臂比指数同有丝分裂细胞相应染色体的数值有很好的一致性。根据SC的相对长度和臂比指数绘制了三种麂的SC组型图。雄性黑麂减数分裂前期形成一个复杂的易位多价体,意味着其核型的演化过程涉及两次染色体易位和一次臂间倒位。 2.在减数分裂前期,性染色体的形态和行为同常染色体的有明显差异,如性染色体嗜银性较强,配对延迟等。XY的配对起始于早粗线期,在中粗线期,Y的全长均同X配对;XY-SC开始解体于晚粗线期。 3.在粗线期,X染色体未配对区域出现自身折叠,形成“发夹”状结构。这种“发夹”结构的形成,可能是在性染色体的进化过程中,X染色体通过不对称易位得到的重复片段在减数分裂前期同源配对的一种细胞学表现。

Comparative Studies on Synaptonemal Complexes in Spermatocytes of Chinese muntjac Muntiacus reevesi,Black muntjac M.crinifrons and Indian muntjac M.muntjak

Surface-spread and silver-stained preparation of spermatocytes of three species of muntjac have been analyzed by electron microscopy.Evidence is presented that autosomal SCs decrease in length from early to late pachytene.The relative lengths and centromeric indexes of each SC are in accordance with those of corresponding mitotic chromosome.Diploid chromosome number of Chinese muntjac M.reevesi is 46 in both sexes,of Indian muntjac M.munijak is 6 in the female,7 in the male,and of Black muntjac M.crinifrons is 8 in the female,9 in the male.A multivalem at pachytene of Black muntjac implies that two translocations and an inversion have occurred during the karyotypic evolution of the animal.Six types of the XY bivalent have been described morphologically.Pairing of the XY starts at early pachytene.At mid-pachytene almost whole Y pairs with X.The XY-SC gradually disappears during late pachytene.The presence of a hair-pinlike structure of the X chromosome suggests that the X chromosome should contain a duplicated segment as a result of an unbalanced translocation between original X and Y chromosome.