| MCP | maximum closure pressure; maximum contraction pattern; malanocortin receptor; melphalan, cyclophosph... |
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| MF | magnetic field; meat free; medium frequency; megafarad; membrane filler; merthiolate-formaldehyde [s... |
| MI | first meiotic metaphase; maturation index; medical illustrator; medical informatics; medical inspect... |
| MTOC | microtubule organizing center; mitotic organizing center |
| NUMA | nuclear mitotic apparatus |
| anterior primary division | <anatomy, nerve> The larger, anterolaterally-directed major terminal branch (with the dorsal primary ramus) of all 31 pairs of mixed spinal nerves, formed at the intervertebral foramen. Most ventral primary rami, especially those involved in the innervation of the limbs, participate in the formation of the major nerve plexuses (cervical, brachial, and lumbosacral) and lose their identities. Most in the thoracic region, however, remain separate from adjacent rami to become the intercostal and subcostal nerves. Ventral primary rami provide innervation to the anterolateral body wall and trunk. Nomina Anatomica lists ventral primary rami as "rami ventrales" for each group of spinal nerves: 1) cervical (nervorum cervicalium ), 2) thoracic (nervorum thoracicorum ), 3) lumbar (nervorum lumbalium ), 4) sacral (nervorum sacralium )m, and 5) coccygeal (nervi coccygei ). Synonym: ramus ventralis nervi spinalis, anterior primary division. (05 Mar 2000) |
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| reduction division | The first cell division in meiosis, the process by which germ cells are formed. A unique event in which the chromosome number is reduced from diploid (46 chromosomes) to haploid (23 chromosomes). Also called first meiotic division or first meiosis. (12 Dec 1998) |
| Remak's nuclear division | <cell biology> An unusual form of nuclear division, in which the nucleus simply constricts, rather like a cell without chromosome condensation or spindle formation. Partitioning of daughter chromosomes is haphazard. Observed in some Protozoa. (18 Nov 1997) |
| cell division | The separation of one cell into two daughter cells, involving both nuclear division (mitosis) and subsequent cytoplasmic division (cytokinesis). (18 Nov 1997) |
| cell division cycle gene | Genes which control the yeast cell cycle. There are around 50 different genes which do this. (09 Oct 1997) |
| cell division cycle mutant | A yeast cell which has cell division cycle genes that have mutated to become sensitive to temperature, at certain temperatures (usually high ones), various parts of the normal yeast cell cycle become abnormal, and in some strains the yeast cell does not survive at all. (09 Oct 1997) |
| cell division phases | The stages which a cell undergoes when dividing. There are four successive phases: prophase, metaphase, anaphase, and telephase. (12 Dec 1998) |
| meiotic division | A specialised form of nuclear division in which there two successive nuclear divisions (meiosis I and II) without any chromosome replication between them. Each division can be divided into 4 phases similar to those of mitosis pro, meta, ana and telophase). Meiosis reduces the starting number of 4n chromosomes in the parent cell to n in each of the 4 daughter cells. Each cell receives only one of each homologous chromosome pair, with the maternal and paternal chromosomes being distributed randomly between the cells. This is vital for the segregation of genes. During the prophase of meiosis I (classically divided into stages: Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis), homologous chromosomes pair to form bivalents, thus allowing crossing over, the physical exchange of chromatid segments. This results in the recombination of genes. Meiosis occurs during the formation of gametes in animals, which are thus haploid and fertilization gives a diploid egg. In plants meiosis leads to the formation of the spore by the sporophyte generation. (18 Nov 1997) |
| cleavage division | The rapid mitotic division of the zygote with decrease in size of individual cells or blastomeres and the formation of a morula. See: cleavage. (05 Mar 2000) |
| multiplicative division | Reproduction by simultaneous division of a mother cell into a number of daughter cells. If the process occurs without fertilization of the mother cell, or encystment, the daughter cells are called merozoites; if they develop within a cyst, and usually after fertilization, they are called sporozoites. (05 Mar 2000) |
| conjugate division | The nuclear division of both haploid nuclei in a dikaryon at the same time (in a dikaryon which has two nuclei). The term is relevant to the biology of fungus. (09 Oct 1997) |
| posterior primary division | <anatomy, nerve> The smaller, posteriorly-directed major terminal branch (with the ventral primary ramus) of all 31 pairs of mixed spinal nerves, formed at the intervertebral foramen and turning abruptly posteriorly to divide into lateral and medial branches, both of which will supply the deep (true) muscles of the back. The medial branch (rami medialis ) of the dorsal primary ramus also supplies articular branches to the zygopophyseal joints and the periosteum of the vertebral arch. In the neck and upper back, the medial branch continues through the deep and superficial back muscles to supply overlying skin; in the lower back, the lateral branch does this. Nomina Anatomica lists dorsal primary rami as "rami dorsales" for each group of spinal nerves: 1) cervical (nervorum cervicalium ), 2) thoracic (nervorum thoracicorum ), 3) lumbar (nervorum lumbalium ), 4) sacral (nervorum sacralium ), and 5) coccygeal (nervi coccygei ). Synonym: ramus dorsalis nervorum spinalium, ramus dorsalis, rami posteriores nervorum spinalium, dorsal branch, posterior primary division. (05 Mar 2000) |
| second meiotic division | The second of two consecutive divisions of the nucleus of an eukaryotic cell during the process of meiosis. It includes the following stages of meiosis: prophase II, metaphase II, anaphase II, and telophase II. (09 Oct 1997) |
| direct nuclear division | <cell biology> An unusual form of nuclear division, in which the nucleus simply constricts, rather like a cell without chromosome condensation or spindle formation. Partitioning of daughter chromosomes is haphazard. Observed in some Protozoa. (18 Nov 1997) |
| division | 1. The act of dividing. 2. <zoology> A rank that if treated as a division of a genus or subgenus is deemed to be of subgeneric rank for the purposes of nomenclature. 3. A taxon at the rank of division. The second highest taxonomic classification for the kingdoms Plantae (plants) and Fungi, between kingdom level and class level. (09 Jan 1998) |