Template:Cell Division terms

Meiosis | Mitosis

• anaphase - (Greek, ana = up, again) Mitosis term referring to the fourth stage, where the paired chromatids now separate and migrate to spindle poles. This is followed by telophase.

• anaphase A - Mitosis term referring to the part of anaphase during which the chromosomes move.

• anaphase B - Mitosis term referring to the part of anaphase during which the poles of the mitotic spindle move apart.

• meiosis - The cell division that occurs only in production of germ cells (oocyte, spermatozoa) where there is a reduction in the number of chromosomes (diploid to haploid) which is the basis of sexual reproduction. All other non-germ cells in the body divide by mitosis. (More? Meiosis | Spermatozoa Development | Oocyte Development | Week 1)

• meiosis I - (MI) The first part of meiosis resulting in separation of homologous chromosomes, in humans producing two haploid cells (N chromosomes, 23), a reductional division.

• meiosis II - (MII) The second part of meiosis. In male human spermatogenesis, producing of four haploid cells (23 chromosomes, 1N) from the two haploid cells (23 chromosomes, 1N), each of the chromosomes consisting of two sister chromatids produced in meiosis I. In female human oogenesis, only a single haploid cell (23 chromosomes, 1N) is produced. Meiosis II: Prophase II - Metaphase II - Anaphase II - Telophase II.

• meiotic silencing of unsynapsed chromatin - (MSUC) An aneuploidy protective mechanism for subsequent generations, during meiosis where chromosomes are silenced that fail to pair with their homologous partners.

• merotelic kinetochore - Cell division abnormality in chromosomal attachment that occurs when a single kinetochore is attached to microtubules arising from both spindle poles. Normal chromosomal attachment in early mitosis, is by only one of the two sister kinetochores attached to spindle microtubules (monotelic attachment) later sister kinetochores attach to microtubules arising from opposite spindle poles (amphitelic attachment).

• metaphase - mitosis term referring to the third stage where mitotic spindle kinetochore microtubules align chromosomes in one midpoint plane. Metaphase ends when sister kinetochores separate. Originally based on light microscopy of living cells and electron microscopy of fixed and stained cells. A light microscope analysis called a "metaphase spread" was originally used to detect chromosomal abnormalities in cells. Mitosis Phases: prophase - prometaphase - metaphase - anaphase - telophase

• metaphase spread - In mitosis using light microscope analysis originally used to detect chromosomal abnormalities in cells, as chromosomes are only visible during cell division.

• mitosis - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid). In germ cell division (oocyte, spermatozoa) meiosis is a modified form of this division resulting in reduction in genetic content (haploid). Mitosis, division of the nucleus, is followed by cytokinesis the division of the cell cytoplasm and the cytoplasmic contents. cytokinesis overlaps with telophase.

• prometaphase - (Greek, pro = before) mitosis term referring to the second stage, when the nuclear envelope breaks down into vesicles. Microtubules then extend from the centrosomes at the spindle poles (ends) and reach the chromosomes. This is followed by metaphase.

• prophase I - meiosis term refers to the first phase of meiosis I, which together with meiosis II results in the reductive cell division only occurring gametes. Prophase can be further divided into a number of stages: leptotene zygotene, pachytene, diplotene, diakinesis.

• telophase - mitosis term referring to the fifth stage, where the vesicles of the nuclear envelope reform around the daughter cells, the nucleoli reappear and the chromosomes unfold to allow gene expression to begin. This phase overlaps with cytokinesis, the division of the cell cytoplasm.