- Cell Biology. part of the process of gamete formation, consisting of chromosome conjugation and two cell divisions, in the course of which the diploid chromosome number becomes reduced to the haploid.Compare mitosis.
- expressive understatement, especially litotes.
noun plural -ses (-ˌsiːz)
- a type of cell division in which a nucleus divides into four daughter nuclei, each containing half the chromosome number of the parent nucleus: occurs in all sexually reproducing organisms in which haploid gametes or spores are producedCompare mitosis See also prophase (def. 2)
- rhetoric another word for litotes
n.“division of a cell nucleus,” 1905, from Greek meiosis “a lessening,” from meioun “to lessen,” from meion “less,” from PIE root *mei- “small” (see minus). Earlier (1580s) it was a rhetorical term, a figure of speech “weak or negative expression used for a positive and forcible one, so that it may be made all the more emphatic,” as when one says “not bad” meaning “very good” or “don’t mind if I do” meaning “I really would like to,” or this example from “Mark Twain”: “YOUNG AUTHOR.” — Yes Agassiz does recommend authors to eat fish, because the phosphorus in it makes brains. So far you are correct. But I cannot help you to a decision about the amount you need to eat,–at least, not with certainty. If the specimen composition you send is about your fair usual average, I should judge that perhaps a couple of whales would be all you would want for the present. Not the largest kind, but simply good, middling-sized whales. Related: meiotic; meiotically. n. pl. mei•o•ses (-sēz′)
- The special process of cell division in sexually reproducing organisms that results in the formation of gametes, consisting of two nuclear divisions in rapid succession that in turn result in the formation of four gametocytes, each containing half the number of chromosomes that is found in somatic cells.
- The process in cell division in sexually reproducing organisms that reduces the number of chromosomes from diploid to haploid (half the original number). Meiosis involves two consecutive divisions of the nucleus and leads to the production of reproductive cells (gametes) in animals and to the formation of spores in plants, fungi, and most algae (the haploid spores grow into organisms that produce gametes by mitosis). Meiosis begins when the chromosomes, which have already duplicated, condense along the center of the nucleus, and pairs of homologous chromosomes undergo crossing over, whereby some of their genetic material is exchanged. The pairs of chromosomes then separate and move to opposite ends of the cell, and the cell itself divides into two cells. In the second stage, each of these two cells also divides into two cells. Meiosis thus produces four cells, each of which contain half the number of chromosomes as the original cell. Some or all of the four cells may become functional gametes or spores. Compare mitosis.
Division of cells in which four “daughter” cells are produced from one “parent” cell, each with half the genes of the parent. Meiosis is a key process in sexual reproduction. In the ovaries and testes, meiosis produces a great variety of sex cells (sperm and ova), because the genes of the parent cell can be split in many different ways. The sex cells combine in fertilization to produce a new individual with the full number of genes — half from each parent. Because the sex cells come in such variety, and come from two parents, there is an enormous number of possible forms for the offspring. (See chromosomes, genetics, and mitosis.)