P rogress through meiosis Molecular interadions Leptotene 细线期 Condensed 八八八Each chromosome has chrom osomes replicated,and consists of become visible,often 2 sister chromatids attached to nuclear envelope 八八NN八八 NN元八八 ae.g. Euk减 Zygotene 合线期 Initiation Chromosomes begin pairing in lim ited 八风 数分裂时的 region or regions 八NN八NN 八八八风八闪 染色单体之 间的交换 P achytene 粗线期 八N八八Strand exchange Synaptonem al complexextends 八八NN Single strands exchange 细菌的 along entire length of paired chromosomes 八N入N 转化，转 风穴N八N 导，接合， Diplotene Chromosomes 代NN Assimilation 噬菌体重组 Region of exchanged separate,but are held strands is extended together by chiasmata VAVAV Diakinesis 冬变期 Chromosomes NM八 Resolution condense,detach 八八入N from envelope; chiasmata remain.All N人风N 4 chromatids become NNN不N visible.细线期 合线期 粗线期 双线期 终变期 ◘ e.g. Euk. 减 数分裂时的 染色单体之 间的交换 细菌的 转化， 转 导，接合， 噬菌体重组