that part of an ovum which undergoes division to form an embryo; = formative yolk n. at formative, adj. n.additions.
| 单词 | θ18938 |
| 释义 | the world > life > biology > biological processes > procreation or reproduction > reproductive substances or cells > [noun] > ovum or ootid > yolk > types of yolk (4) germ yolk1849 that part of an ovum which undergoes division to form an embryo; = formative yolk n. at formative, adj. n.additions. archiblast1876 The formative yolk in an ovum, which constitutes the germ; also applied to the epiblast. (In both uses distinguished from parablast, n. 2.) parablast1876 Embryology. Esp. in the terminology of W. His: a layer of cells that gives rise to the blood vessels and connective tissue of the embryo (embryonic… tropholecithus1879 (Haeckel's name for) the part of the yolk of a meroblastic ovum which serves a purely nutritive function; cf. morpholecithus, n. |
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