meiosissel

Meiosissel is a term used in some texts to describe a cell that is undergoing meiosis or is programmed to enter meiosis. More common terms are meiocyte or sporocyte. These cells are typically diploid germ cells found in the reproductive tissues of many organisms, including animals (testes and ovaries) and plants (anthers and ovules), where they give rise to haploid gametes or spores.

Meiosis comprises two consecutive divisions, meiosis I and meiosis II, following DNA replication in S phase. During meiosis I, homologous chromosomes pair and undergo recombination through crossing over during prophase I (synapsis). This genetic exchange between nonsister chromatids increases genetic diversity. Homologous chromosomes then disjoin and are pulled to opposite poles in anaphase I, producing two haploid cells by telophase I. In meiosis II, a second round of division separates sister chromatids, resulting in four haploid cells.

In males, meiosis leads to four equal sperm; in females, cytokinesis is asymmetric and often yields one functional gamete and polar bodies, depending on species. The resulting haploid products carry different combinations of alleles, contributing to genetic variation in offspring.

Meiosis is tightly regulated by meiosis-specific proteins and cyclin-dependent kinases. It typically begins in germ cells after appropriate developmental cues and, in many animals, includes arrest of oocytes at prophase I until puberty or fertilization.

Errors in meiosis, such as nondisjunction, can produce aneuploid progeny and are a major cause of developmental disorders. Overall, meiosissel denotes a cell stage critical for sexual reproduction and genetic diversification of populations.