Tetrad nature of bivalents is very clearly visible in which stage of prophase I of meiosis?

In zygotene the complex formed by a pair of synapsed homologous chromosomes is called a bivalent. This is more clearly visible at the pachytene stage as tetrad because each bivalent shows clear visibility of four. During pachytene, the four chromatids of each bivalent chromosomes become distinct and clearly appears as tetrads.