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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.



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).

References in periodicals archive ?
Epiboly starts with the deep layer cells radially intercalating and the yolk cell "doming," which was recorded by Andrade-Talmelli et al.
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).
In order to evaluate the role of VPA in zebrafish notochord formation, the wild type zebrafish embryos were treated with various concentrations of VPA (20 to 40 -M from 50% epiboly stage for 18 h.
At approximately 13 hours postfertilization, epiboly began, and involution marked the start of gastrulation.
Gastrulation requires the migration of blastodermic cells over the yolk in the process of epiboly (Fig.
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.
Gastrulation occurs by emboly, epiboly, or some combination of the two (Casteel, 1904; Thompson, 1958; Gohar and Soliman, 1967a, b; Soliman, 1978).
5[degrees]C to 50% epiboly (5--6 hr) before use in exposure studies.
Immediately preceding injection, dead embryos or embryos that had completed epiboly were replaced, and the well water covering the embryos was replaced with a sterile saline solution.
As epiboly proceeds, the cells that express gastropod Hb-like protein most intensely line the leading edge of the ectoderm as shown in I.
1992); however, to ensure that spontaneous egg activation was not erroneously interpreted as fertilization, only embryos that progressed to the epiboly stage of development (about 24 h after fertilization) were deemed fertilized.