| 单词 | vitelline sac |
| 释义 | > as lemmasvitelline sac b. vitelline membrane, vitelline sac, the transparent membrane which surrounds the yolk of an egg; the yolk-sac; the investing membrane of the embryo. ΘΚΠ the world > life > biology > biological processes > procreation or reproduction > reproductive substances or cells > [noun] > ovum or ootid > yolk > sac yolk sac1831 vitelline membrane1845 vitellicle1852 vitelline sac1880 1845 R. B. Todd & W. Bowman Physiol. Anat. I. 48 The first, or the vitelline membrane of the ovum, is the wall of a cell. 1861 J. R. Greene Man. Animal Kingdom II. 15 In addition to these parts, many ova are provided with an outer envelope, known as the yolk-sac or ‘vitelline membrane’. 1880 A. Günther Introd. Study of Fishes 166 Generally the vitelline sac of the embryoes is free. < as lemmas |
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