holoblastic

[hol-uh-blas-tik, hoh-luh-]

adjective

Embryology.

1. (of certain eggs) undergoing total cleavage, resulting in equal blastomeres.

holoblastic

/ ˌhɒləˈblæstɪk /

adjective

1. embryol of or showing cleavage of the entire zygote into blastomeres, as in eggs with little yolk Compare meroblastic

Other Word Forms

• holoblastically adverb

Word History and Origins

Origin of holoblastic¹

1870–75; holoblast ( holo- + -blast ) + -ic

Example Sentences

Holoblastic, hol-o-blas′tik, adj. undergoing segmentation throughout the entire mass, as the ova of mammals.

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Broadly speaking, they fall first into two groups: the older cyclostoma, the earliest fishes, most of the amphibia, and the viviparous mammals, have holoblastic ova—that is to say, ova with total, unequal segmentation; while the younger cyclostoma, most of the fishes, the cephalopods, reptiles, birds, and monotremes, have meroblastic ova, or ova with partial discoid segmentation.

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Although the mass of the food-yelk may be very large in the ova of the discoblastic vertebrates, nevertheless in every case a blastula is developed from the morula, as in the holoblastic ova.

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