| 释义 |
blastula Embryol.|ˈblæstjʊlə|
[mod.L., f. Gr. βλαστός sprout + dim. suffix (see -ule). Cf. blastule.]
An embryo, typically composed of cells arranged in a sphere enclosing the blastocœle. Hence blastuˈlation, the formation of the blastula.
1887A. C. Haddon Introd. Study Embryol. ii. 21 The result of segmentation is the formation of a multicellular body, usually enclosing a central cavity—‘Segmentation cavity’ or ‘Blastocœl’. The body itself is variously called ‘Blastula’ or ‘Blastosphere’. Ibid. ii. 50 Segmentation..of Sponges..results in the formation of a hollow blastula. 1889Cent. Dict., Blastulation. 1893Tuckey Hatschek's Amphioxus 43 An equal segmentation leading to a blastula without any well-defined main axis. 1924E. W. Macbride Stud. Heredity iii. 70 When the [sea-urchin's] egg has divided into about 1000 cells these form a little hollow balloon or vesicle known as the blastula. 1931J. Needham Chem. Embryol. II. iii. iv. 642 Vles concluded that blastulation involves a change of some kind in the metabolism of the embryo. 1962D. Nichols Echinoderms x. 120 The resulting blastula is oval, hollow and ciliated all over. |