Question

In which stage of meiosis, chromosomes appear thick and short and located near the periphery of the nucleus?

Answer 1

Meiosis in Greek meiosis means "lessening". It is a type of cell division of germ cells in sexually-reproducing organisms used to produce the gametes, such as sperm or egg cells. It involves two rounds of division which ultimately result in four cells with only one copy of each chromosome (haploid).

Complete Answer:
Meiosis takes place through two processes meiosis I and meiosis II. These are further divided into Karyokinesis I and Cytokinesis I and Karyokinesis II and Cytokinesis II respectively. Meiosis I separates replicated homologous chromosomes (each made up of two sister chromatids), into two daughter cells. Thus, the chromosome number is reduced by half by half. During meiosis II, the sister chromatids decouple and the resultant daughter chromosomes are segregated into four daughter cells.
Since meiosis involves two rounds of chromosome segregation, the cell undergoes prophase twice, i.e., prophase I and prophase II. Prophase I is the most complex phase in all of meiosis since homologous chromosomes form pairs and exchange genetic information. It is divided into five phases: leptotene, zygotene, pachytene, diplotene, and diakinesis.
In the leptotene stage (from the Greek for "delicate"), chromosomes begin to condense. In the second phase of prophase I, zygotene (from the Greek for "conjugation"), all maternally and paternally derived chromosomes find their homologous partner. In the pachytene stage, recombination nodules facilitate genetic exchange between the non-sister chromatids of the synaptonemal complex in an event known as crossing-over or genetic recombination. During the diplotene stage (from Greek words meaning "two threads"), the synaptonemal complex disassembles and homologous chromosomes separate from one another a little.
In the fifth and final phase of prophase I, diakinesis (from the Greek for "double movement"), full chromatin condensation occurs and all four sister chromatids can be seen in bivalents. This is the first point in meiosis where all the four parts of the tetrads are actually visible. Sites of crossing over can be seen entangled together, effectively overlapping. Thus, chiasmata is clearly visible. The chromosomes appear thick and short and are located near the periphery of the nucleus.

Note:
In prophase II, we see the disappearance of the nucleoli and the nuclear envelope as well as the shortening and thickening of the chromatids. Centrosomes move to the polar region and arrange spindle fibres for the second meiotic division. Interphase is the stage before meiosis I which is then followed by meiosis II. In some species, cells enter a resting phase known as interkinesis in between meiosis I and meiosis II.