| mitotic division | <cell biology> A method of indirect division of a cell, consisting of a complex of various processes, by means of which the two daughter nuclei normally receive identical complements of the number of chromosomes characteristic of the somatic cells of the species. Mitosis, the process by which the body grows and replaces cells, is divided into four phases. 1. Prophase: formation of paired chromosomes, disappearance of nuclear membrane, appearance of the achromatic spindle, formation of polar bodies. 2. Metaphase: arrangement of chromosomes in the equatorial plane of the central spindle to form the monaster. Chromosomes separate into exactly similar halves. 3. Anaphase: the two groups of daughter chromosomes separate and move along the fibres of the central spindle, each toward one of the asters, forming the diaster. 4. Telophase: the daughter chromosomes resolve themselves into a reticulum and the daughter nuclei are formed, the cytoplasm divides, forming two complete daughter cells. NOTE: the term mitosis is used interchangeably with cell division, but strictly speaking it refers to nuclear division, whereas cytokinesis refers to division of the cytoplasm. In some cells, as in many fungi and the fertilized eggs of many insects, nuclear division occurs within the cell unaccompanied by division of the cytoplasm and formation of daughter cells. (13 Nov 1997) |
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| mitotic figure | The microscopic appearance of a cell undergoing mitosis; a cell of which the chromosomes are visible by the light microscope. (05 Mar 2000) |
| mitotic index | <cell biology, molecular biology> The fraction of cells in a sample that are in mitosis. It is a measure of the relative length of the mitotic phase of the cell cycle. (18 Nov 1997) |
| mitotic nondisjunction | Failure of the two members of a chromosome pair to separate (disjoin) during mitosis so that both go to one daughter cell and none to the other. (12 Dec 1998) |
| mitotic period | The period of the cell cycle in which all phases of mitosis occur. Synonym: M phase. (05 Mar 2000) |
| mitotic rate | The proportion of cells in a tissue that are undergoing mitosis, expressed as a mitotic index or, roughly, as the number of cells in mitosis in each microscopic high-power field in tissue sections. (05 Mar 2000) |
| mitotic recombination | <genetics, molecular biology> Somatic crossing over. Crossing over can occur between homologous chromosomes during mitosis, but is very rare because the chromosomes do not normally pair. When it occurs it can lead to new combinations of previously linked genes. Although infrequent, mitotic recombination has been utilised for genetic analysis in Aspergillus and in studies on developmental compartments in Drosophila where the frequency of mitotic recombination can be increased by X irradiation. (18 Nov 1997) |
| mitotic segregation | <genetics> Mitotic recombination. (18 Nov 1997) |
| mitotic shake off method | <cell biology, procedure> A method of collecting cells in mitosis, so that the chromosomes can be examined and the karyotype determined. Many cultured cells round up during mitosis and so become less firmly attached to the culture substratum. Cells in mitosis thus can be removed into suspension by gentle shaking of the culture vessel, leaving the nonmitotic cells still attached. The number of cells that are in mitosis is usually increased by using a drug, such as colcemid that blocks mitosis at metaphase. (18 Nov 1997) |
| mitotic spindle | See: spindle and mitosis. (18 Nov 1997) |
| mitotic spindle apparatus | An organelle consisting of three components: 1) the astral microtubules, which form around each centrosome and extend to the periphery; 2) the polar microtubules which extend from one spindle pole to the equator; and 3) the kinetochore microtubules, which connect the centromeres of the various chromosomes to either centrosome. (12 Dec 1998) |
| mitoxantrone | <chemical> An anthracenedione antineoplastic agent. It is particularly effective against advanced breast cancer, acute leukaemia, and malignant lymphoma. It has mild side effects, especially with respect to nausea, vomiting, hair loss, and cardiotoxicity. Pharmacological action: analgesics, antineoplastic agent. Chemical name: 9,10-Anthracenedione, 1,4-dihydroxy-5,8-bis((2-((2-hydroxyethyl)amino)ethyl)amino)- (12 Dec 1998) |
| mitoxantrone hydrochloride | 1,4-Dihydro-5,8-bis[[2-[2-hydroxyethyl)-amino]ethyl]anthraquinone dihydrochloride;a synthetic anti-neoplastic used intravenously in the initial therapy for acute nonlymphocytic leukaemia in adults. (05 Mar 2000) |
| mitral | Pertaining to a miter; resembling a miter; as, the mitral valve between the left auricle and left ventricle of the heart. Origin: Cf. F. Mitral. See Miter. Source: Websters Dictionary (01 Mar 1998) |
| mitral area | The region of the chest over the apex of the heart, where the sounds, normal or pathologic, produced at the mitral valves are usually heard most distinctly. (05 Mar 2000) |