| 释义 |
blastula
blas·tu·la B0316600 (blăs′chə-lə)n. pl. blas·tu·las or blas·tu·lae (-lē′) An early embryonic form produced by cleavage of a fertilized ovum and consisting of a spherical layer of cells surrounding a fluid-filled cavity. Also called blastosphere.
[New Latin : from Greek blastos, bud + Latin -ula, feminine diminutive suff.]
blas′tu·lar adj.blas′tu·la′tion (-lā′shən) n.blastula (ˈblæstjʊlə) n, pl -las or -lae (-liː) (Biology) an early form of an animal embryo that develops from a morula, consisting of a sphere of cells with a central cavity. Also called: blastosphere [C19: New Latin; see blasto-] ˈblastular adjblas•tu•la (ˈblæs tʃə lə)
n., pl. -las, -lae (-ˌli) the early developmental stage of an animal, following the morula stage and consisting of a single spherical layer of cells enclosing a hollow, central cavity. Compare blastocyst. [1885–90; < Greek blast(ós) bud, sprout + New Latin -ula -ule] blas′tu•lar, adj. blas`tu•la′tion (-ˈleɪ ʃən) n. blas·tu·la (blăs′chə-lə) Plural blastulas or blastulae (blăs′chə-lē′) An embryo at the stage immediately following the division of the fertilized egg cell, consisting of a ball-shaped layer of cells around a fluid-filled cavity. Compare gastrula.Thesaurus| Noun | 1. |  blastula - early stage of an embryo produced by cleavage of an ovum; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occursblastosphereconceptus, fertilized egg, embryo - an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval lifeblastocele, blastocoel, blastocoele, cleavage cavity, segmentation cavity - the fluid-filled cavity inside a blastulablastocyst, blastodermic vessicle - the blastula of a placental mammal in which some differentiation of cells has occurredtrophoblast - the membrane that forms the wall of the blastocyst in early development; aids implantation in the uterine wall; "after implantation of the blastocyst in the uterine wall the trophoblast divides into two layers, the chorion and the placenta" |
TranslationsBlastula
blastula[′blas·chə·lə] (embryology) A hollow sphere of cells characteristic of the early metazoan embryo. Blastula a stage in the development of the embryo of multicellular animals culminating in cleavage. The structure of the embryo in the blastula stage depends on the structure of the egg and type of cleavage. Radial cleavage (echinoderms, lancelets, amphibians, sturgeon) gives rise to a coeloblastula, a spherical embryo with a cavity, or blastocoel, which is filled with a fluid differing in chemical composition from the medium surrounding the embryo. The blastocoel is sometimes in the center of the blastula but is generally shifted to the animal (upper) part of the embryo. The blastular wall, the blastoderm, consists of one, several, or many rows of cells. In animals with the spiral type of cleavage (most mollusks and some worms, for example), the blastula is formed without a cavity, a sterroblastula. Animals with incomplete (partial) discoidal cleavage (bony fishes, sharks, reptiles, birds) form a discoblastula whose cavity is reduced; the upper wall consists of many rows of cells while the lower uncleaved wall contains the yolk. Partial superficial cleavage (some arthropods) gives rise to a blastula in which the cavity is filled with yolk. Cleavage of eggs in mammals and man ends in the formation of blastocysts rather than blastulas. blastula
blastula [blas´tu-lah] (pl. blas´tulae) (L.) the usually spherical body produced by cleavage of a fertilized ovum (zygote), consisting of a single layer of cells (blastoderm) surrounding a fluid-filled cavity (blastocoele); it follows the morula stage.blas·tu·la (blas'tū-lă), An early stage of an embryo formed by the rearrangement of the blastomeres of the morula to form a hollow sphere. [G. blastos, germ] blastula (blăs′chə-lə)n. pl. blastu·las or blastu·lae (-lē′) An early embryonic form produced by cleavage of a fertilized ovum and consisting of a spherical layer of cells surrounding a fluid-filled cavity. Also called blastosphere.
blas′tu·lar adj.blas′tu·la′tion (-lā′shən) n.blastula A hollow sphere formed during the early embryonic development of higher animals—which follows the morular stage of embryogenesis—in which dividing cells line up on the outside and are bathed by fluid within the adjacent cavity (blastocoele). In animals where cleavage involves the whole egg, the blastula consists of a ball of cells with a hollow centre.blas·tu·la (blas'chŭ-lă) An early stage of an embryo formed by the rearrangement of the blastomeres of the morula to form a hollow sphere. [G. blastos, germ] Fig. 70 Blastula . Formulation of the blastula by cell cleavage. blastula or blastophere a stage in the development of an embryo, where the embryo consists of a hollow ball of cells with a central cavity (a MORULA) formed by a process of CLEAVAGE. Invagination (in-pushing of the ball at one side) of cells into the blastula gives rise to the GASTRULA. See ARCHENTERON (Fig. 44).blastula
Related to blastula: gastrulation, archenteronSynonyms for blastulanoun early stage of an embryo produced by cleavage of an ovumSynonymsRelated Words- conceptus
- fertilized egg
- embryo
- blastocele
- blastocoel
- blastocoele
- cleavage cavity
- segmentation cavity
- blastocyst
- blastodermic vessicle
- trophoblast
|