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The growing or extending of one part, such as the upper hemisphere of a blastula, over and around another part, such as the lower hemisphere, in embryogenesis.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a method of gastrulation by which cells of the embryo’s animal hemisphere spread through its vegetal hemisphere, the future entoderm (in animals with meroblastic ova, the yolk).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In screening the morphological development of haploid and diploid embryos; assembly of cell cycle, axis, epiboly at 12nd hour; general body shape, eyes, notocord and death cells at time between 24th-30th hour; hearth beat, blood cells, pectoral fins and newly death cells at time between 48th-54th and swimming movement and embryo death at time between72nd -78th hour were observed [2].
The beginning of gastrula marks the end of the blastula stage, and it is followed by epiboly, defined as the movement of the yolk syncytial layer and blastodisc around the yolk cell.
With the cleavage proceeding and embryonic development, the amount of transcript was slightly increased without significant difference until 30% epiboly stage or sphere stage, and then strongly increased to the peak at 27-somite stage, then gradually decreased until 1DAH (day after hatched).
The compounds were added to embryos at 50% epiboly stage (6 h post fertilization).
In these screening assays, we found that static exposure of zebrafish embryos from 5.25 hr postfertilization (hpf) (50% epiboly) to 96 hpf to TCEP, TCPP, or V6 at concentrations as high as 50 [micro]M resulted in no significant effects on embryonic survival or development.
At midblastula, cells of the blastoderm become mobile and spread over the yolk in the process known as epiboly. Gastrulation begins dorsally with involution of deep blastoderm cells to form an outer epiblast and inner hypoblast.
This toxic effect may be due to the blockade of DNA synthesis elicited by organophosphonc pesticides causing diminished number of blastodermic cells at the time of epiboly, thus hindering the start of invagination.
Important developmental processes observed included cleavage, formation of a blastula, epiboly, gastrulation, neurulation, organogenesis, and hatching.
Several mutations even disrupted epiboly, the very first cellular move- ments of the embryo.
4C): the germ ring became distinct and epiboly proceeded until the germ ring was in center of the egg.
Gastrulation occurs by emboly, epiboly, or some combination of the two (Casteel, 1904; Thompson, 1958; Gohar and Soliman, 1967a, b; Soliman, 1978).
2003), and embryos were allowed to recover in system water at 28.5[degrees]C to 50% epiboly (5--6 hr) before use in exposure studies.