Question

Why is the pachytene stage referred to as the tetrad stage?

Answer 1

Meiosis and mitosis are two parts of cell division: they create egg and sperm cells. Where a cell duplicates its contents and forms two identical daughter cells. Cells divide and reproduce in many stages and in mitosis there are four stages- zygotene, diplotene, pachytene and kinesis. The cells tend to multiply in telophase.

Complete answer:
As Pachytene is a stage in meiosis, they pair and the corresponding portions of the chromosomes in this stage are side to side. The chromosomes multiply and contract into pairs. The paired chromatids contract and this stage of paired chromosomes is referred to as tetrad.
Tetrad stage is the number of chromosomes which consists of four chromatids. Pachytene stage is often referred to as tetrad because at the end of prophase I, the chromosome pairs are being held together at the chiasmata.
Because of the four sister chromatids aligning to each other, each pair of homologous chromosomes are visible. In prophase I of meiosis, and metaphase I, the pairs line up and the midway point crosses and cells move towards poles.
Basically, tetrads are homologous chromosomes in pairs, four sister chromatids, which can be seen in prophase I. otherwise the chromosomes do not retain in pairing.

Note:
Pachytene is the stage where the chromosomes are synapsed and fully connected end-to-end by a synaptonemal complex. The synapsed unit of chromosomes is referred to as tetrad. During the meiotic recombination time, DNA repair mechanisms tend to favor template DNA repair over sister chromatids.