Q.Write about Pachytene and Diplotene of Prophase I

Meiosis (Greek meioum, 'to reduce') is the specialised nuclear division confined to the reproductive organs that produces gametes with half the parent cell's chromosome number, and it is unique for involving synapsis, crossing over, and reduction division. It comprises two successive divisions. Meiosis I is the reductional division: in prophase I - the longest, most complex stage, with five substages (leptotene, zygotene, pachytene, diplotene, diakinesis) - homologous chromosomes pair up by synapsis to form bivalents/tetrads, and crossing over between non-sister chromatids is initiated at pachytene and marked by chiasmata visible from diplotene onward; metaphase I aligns whole bivalents at the equator with random (independent-assortment) orientation; anaphase I separates whole homologous chromosomes (not sister chromatids) to opposite poles, the actual point of chromosome-number reduction; telophase I forms two haploid daughter nuclei, briefly separated from meiosis II by interkinesis (no …