| BLLD | British Library Lending Division |
|---|---|
| BSDLB | block in anterosuperior division of left branch |
| CDK | cell division kinase; climatic droplet keratopathy; cyclin-dependent kinase |
| CHSD | Children's Health Services Division |
| DAC | derived air concentration; digital-to-analog converter; disaster assistance center; Division of Ambu... |
| cell division phases | The stages which a cell undergoes when dividing. There are four successive phases: prophase, metaphase, anaphase, and telephase. (12 Dec 1998) |
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| 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) |
| 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) |
| 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) |
| 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) |
| division septum | <cell biology> The cell wall that forms between daughter cells at the end of mitosis in plant cells or just before separation in bacteria. (18 Nov 1997) |
| equatorial division | Nuclear division in which each chromosome divides equally. (05 Mar 2000) |
| first meiotic division | The first of two consecutive divisions of the nucleus of an eukaryotic cell during the process of meiosis. It includes the following stages of meiosis: prophase I, metaphase I, anaphase I, and telophase I. (09 Oct 1997) |
| receptors, cytoplasmic and nuclear | Proteins in the cytoplasm or nucleus that specifically bind signalling molecules and trigger changes which influence the behaviour of cells. The major groups are the steroid hormone receptors, which usually are found in the cytoplasm, and the thyroid hormone receptors, which usually are found in the nucleus. Receptors, unlike enzymes, generally do not catalyze chemical changes in their ligands. (12 Dec 1998) |
| Pelger-Huet nuclear anomaly | Congenital inhibition of lobulation in the nuclei of neutrophilic leukocytes; most cells present band or bilobulate appearance, and only an occasional cell is trilobed; it is not associated with disease, but may be confused with leukocyte "shift to left"; autosomal dominant inheritance. (05 Mar 2000) |
| ribonucleoproteins, small nuclear | Highly conserved nuclear RNA-protein complexes that function in RNA processing in the nucleus, including pre-mRNA splicing and pre-mRNA 3'-end processing in the nucleoplasm. The u3 snrnp is localised in the nucleolus, where it aligns into base pairs with the 28s rrna precursor in a still unidentified region and functions in pre-rrna processing. The u7 snrnp aligns into base pairs with a conserved sequence in the 3'-end of histone pre-mRNA and is an essential cofactor for the cleavage that creates the mature nonadenylated 3'-end. (12 Dec 1998) |