Villagómez D A
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala.
Hereditas. 1993;118(1):87-99. doi: 10.1111/j.1601-5223.1993.t01-3-00087.x.
Synaptonemal complex analysis, by electron microscopy of spread spermatocytes after phosphotungstic acid staining, made possible description of the chromosomal synaptic patterns and the synaptonemal complex karyotype of the pig (Sus scrofa domestica). The autosomal synaptic pattern in conjunction with the sex chromosome morphology and pairing behaviour can serve as a reference for the meiotic cell progression from the zygotene stage to the pachytene. The autosomes started terminal synapsis at early zygotene (Z1) and at mid-zygotene (Z2) some of the small bivalents were completely paired. The extension of pairing between the X and the Y chromosome, and the differentiation of their axes, disclosed seven types of sex bivalent (Types 0-VI). The Type 0 sex bivalent occurred in late zygotene (Z3), at which the X and Y axes began terminal synapsis by their short arms. Each one of the pachytene substages, early, mid-, and late, included two sex bivalent types. By early pachytene (P1-P2) the entire Y chromosome was paired with the X axis. Subsequently, progressive desynapsis and differentiation of the sex chromosome axes defined the mid- (P3-P4) and late pachytene substages (P5-P6). At mid-pachytene, the unpaired XY segments were associated end-to-end and showed differing degrees of complexity (thickening, splitting, despiralization and strandedness). These axial complexities were replaced at late pachytene by fine excrescences along the sex chromosome axes, which still formed a short SC stretch. Additionally, an attempt to construct an SC karyotype for the pig is presented. There was general agreement between the autosomal SC karyotype and the autosomal somatic karyotype when comparisons were made, considering the relative lengths and arm ratios of individual chromosome pairs.
通过对经磷钨酸染色的伸展精母细胞进行电子显微镜观察来分析联会复合体，使得描述猪（家猪）的染色体联会模式和联会复合体核型成为可能。常染色体联会模式与性染色体形态及配对行为相结合，可作为减数分裂细胞从偶线期到粗线期进程的参考。常染色体在偶线期早期（Z1）开始末端联会，在偶线期中期（Z2）一些小的二价体完全配对。X和Y染色体之间配对的延伸及其轴的分化，揭示了七种性二价体类型（0 - VI型）。0型性二价体出现在偶线期晚期（Z3），此时X和Y轴通过其短臂开始末端联会。粗线期的每个亚阶段，即早期、中期和晚期，都包括两种性二价体类型。在粗线期早期（P1 - P2），整个Y染色体与X轴配对。随后，性染色体轴的逐渐解联会和分化定义了粗线期中期（P3 - P4）和晚期亚阶段（P5 - P6）。在粗线期中期，未配对的XY片段端对端相连，显示出不同程度的复杂性（增厚、分裂、解螺旋和绞合）。这些轴的复杂性在粗线期晚期被沿性染色体轴的精细突出物所取代，这些突出物仍形成一段短的联会复合体片段。此外，还尝试构建猪的联会复合体核型。在比较时，考虑到各个染色体对的相对长度和臂比，常染色体联会复合体核型与常染色体体细胞核型之间总体一致。
