| germ cell | Cell specialised to produce haploid gametes. The germ cell line is often formed very early in embryonic development. (18 Nov 1997) |
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| germ cell tumour | A type of brain tumour. (12 Dec 1998) |
| primordial germ cell | The most primitive undifferentiated sex cell, found initially outside the gonad. Synonym: gonocyte. (05 Mar 2000) |
| neoplasms, germ cell and embryonal | Neoplasms composed of primordial germ cells of embryonic gonads or of elements of the germ layers of the embryo. The concept does not refer to neoplasms located in the gonads or present in an embryo or foetus. (12 Dec 1998) |
| mixed cell leukaemia | Term infrequently used as a designation for granulocytic leukaemia, thereby emphasizing the occurrence of different types of cells in the myeloid series (i.e., neutrophilic, eosinophilic, and basophilic granulocytes), in contrast to the comparatively monotonous pattern observed in lymphocytic and monocytic leukaemia. (05 Mar 2000) |
| lymphoma, mixed-cell | Malignant lymphoma characterised by the presence of a mixed population of cells, with the smaller cells resembling lymphocytes and the larger ones histiocytes. It usually presents in a nodular (follicular) pattern, but may evolve into a diffuse pattern. (12 Dec 1998) |
| lymphoma, mixed-cell, diffuse | A heterogeneous group of intermediate-grade lymphomas of mixed cellular composition. Although they have not been extensively studied, it appears that they are predominantly B-cell diseases. (12 Dec 1998) |
| lymphoma, mixed-cell, follicular | A low-grade malignant lymphoma of follicular pattern in which there is no clear preponderance of one cell type (small or large) over another. The large cells, cleaved or noncleaved, are often 2-3 times larger in diameter than normal lymphocytes. (12 Dec 1998) |
| germ | 1. <biology> That which is to develop a new individual; as, the germ of a foetus, of a plant or flower, and the like; the earliest form under which an organism appears. "In the entire process in which a new being originates . Two distinct classes of action participate; namely, the act of generation by which the germ is produced; and the act of development, by which that germ is evolved into the complete organism." (Carpenter) 2. That from which anything springs; origin; first principle; as, the germ of civil liberty. <biology> Disease germ, the theory that living organisms can be produced only by the evolution or development of living germs or seeds. See Biogenesis, and Abiogenesis. As applied to the origin of disease, the theory claims that the zymotic diseases are due to the rapid development and multiplication of various bacteria, the germs or spores of which are either contained in the organism itself, or transferred through the air or water. See Fermentation theory. Origin: F. Germe, fr. L. Germen, germinis, sprout, but, germ. Cf. Germen, Germane. Source: Websters Dictionary (01 Mar 1998) |
| germ cells | The reproductive cells in multicellular organisms. (12 Dec 1998) |
| germ-free animal | An animal which has no microorganisms whatsoever living in or on it. An animal which was born and raised in an isolated environment with no microorganisms in it, such as within a germ-free isolator. (09 Oct 1997) |
| germ-free isolator | A chamber which has absolutely no microorganisms whatsoever living in it, where a germ-free animal can be born and raised. An artificial barrier surrounding a living facility for germ-free animals, which keeps out all microorganisms. (09 Oct 1997) |
| germ-free life | Animals not contaminated by or associated with any foreign organisms. (12 Dec 1998) |
| germ layer | <embryology> A layer of cells produced during the process of gastrulation during the early development of the animal embryo, which is distinct from other such layers of cells, as an early step of cell differentiation. The three types of germ layers are the endoderm, ectoderm, and mesoderm. Diploblastic organisms (e.g. Coelenterates) have two layers, ectoderm and endoderm, triploblastic organisms (all higher animal groups) have mesoderm between these two layers. Germ layers become distinguishable during late blastula/early gastrula stages of embryogenesis and each gives rise to a characteristic set of tissues, the ectoderm to external epithelia and to the nervous system for example: although some tissues contain elements derived from two layers. (18 Nov 1997) |
| germ layers | The three layers of cells comprising the early embryo. (12 Dec 1998) |