from The Century Dictionary and Cyclopedia
- n. In embryology, a disk-gastrula; that special form of metagastrula or kinogenetic gastrula which results from discoidal egg-cleavage, or discoidal segmentation of the vitellus.
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From the discogastrula of the former was evolved the distinctive epigastrula of the latter.
In contrast to the two chief forms of gastrula we considered previously, we give the name of discoid gastrula (discogastrula, Figure 1.54) to this third principal type.
Richard Semon in 1894, there could be little doubt, in view of the great size of their food-yelk, that their ovum-segmentation was discoid, and led to the formation of a sickle-mouthed discogastrula, as in the case of the reptiles and birds.
We shall return to this discogastrula in Chapter 1.9.
(From Duval.) ud primitive gut, vl, hl fore and hind lips of the primitive mouth; ak, ik outer and inner germinal layers; vr fore-border of the discogastrula.)
Discoid gastrula (discogastrula) of a bony fish. e ectoderm, i entoderm, w border-swelling or primitive mouth, n albuminous globule of the nutritive yelk, f fat-globule of same, c external membrane (ovolemma), d partition between entoderm and ectoderm (earlier the segmentation-cavity).)
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