*oblast*

n. [ Gr. &unr_; color + -blast. ] An embryonic cell which develops into a pigment cell. [ 1913 Webster ]

n. [ Cnida + -blast. ] (Zool.) One of the cells which, in the Cœlenterata, develop into cnidæ. [ 1913 Webster ]

n. [ Gr. ky`tos hollow vessel + -blast. ] (Biol.) The nucleus of a cell; the germinal or active spot of a cellule, through or in which cell development takes place. [ 1913 Webster ]

n. [ NL., fr. Gr. ky`tos hollow vessel + &unr_;&unr_;&unr_;&unr_; growth. ] (Biol.) See Protoplasm. [ 1913 Webster ]

a. [ Gr. &unr_; doublet + -blast + -ic. ] (Biol.) Characterizing the ovum when it has two primary germinal layers. [ 1913 Webster ]

a. [ Gr. &unr_; disk + &unr_; to grow. ] (Biol.) Applied to a form of egg cleavage seen in osseous fishes, which occurs only in a small disk that separates from the rest of the egg. [ 1913 Webster ]

n. [ Ecto- + Gr. &unr_; bud, germ. ] (Biol.) (a) The outer layer of the blastoderm; the epiblast; the ectoderm. (b) The outer envelope of a cell; the cell wall. Agassiz. [ 1913 Webster ]

n. [ Endo- + -blast. ] (Biol.) Entoblast; endoplast. See Nucleus, [ 1913 Webster ]

a. (Biol.) Relating to the endoblast; as, the endoblastic layer.

n. [ Ento- + -blast. ] (Biol.) The inner germ layer; endoderm. See Nucleolus. [ 1913 Webster ]

n. [ Gr. 'e`ntosthe from within + -blast. ] (Biol.) The granule within the nucleolus or entoblast of a nucleated cell. Agassiz. [ 1913 Webster ]

n. a nucleated cell in bone marrow from which red blood cells develop. [ WordNet 1.5 ]

n. [ See Gonoblastidium. ] (Zool.) A reproductive bud of a hydroid; a simple gonophore. [ 1913 Webster ]

‖n.; pl. Gonoblastidia [ NL., fr. Gr. &unr_; offspring + &unr_; to bud. ] (Zool.) A blastostyle. [ 1913 Webster ]

‖n. pl. [ NL. fr. Gr. gymno`s naked + blasta`nein to sprout. ] (Zool.) The Athecata; -- so called because the medusoid buds are not inclosed in a capsule. [ 1913 Webster ]

a. (Zool.) Of or pertaining to the Gymnoblastea. [ 1913 Webster ]

n. [ Haemato- + -blast. ] (Anat.) One of the very minute, disk-shaped bodies found in blood with the ordinary red corpuscles and white corpuscles; a third kind of blood corpuscle, supposed by some to be an early stage in the development of the red corpuscles; -- called also blood plaque, and blood plate. [ 1913 Webster ]

n. [ Holo + -blast. ] (Biol.) an ovum composed entirely of germinal matter. See Meroblast. [ 1913 Webster ]

a. (Biol.) Undergoing complete segmentation; composed entirely of germinal matter, the whole of the yolk undergoing fission; -- opposed to meroblastic. [ 1913 Webster ]

n. [ Pref. hypo- + -blast. ] (Biol.) The inner or lower layer of the blastoderm; -- called also endoderm, entoderm, and sometimes hypoderm. See Illust. of Blastoderm, Delamination, and Ectoderm. [ 1913 Webster ]

a. (Biol.) Relating to, or connected with, the hypoblast; as, the hypoic sac. [ 1913 Webster ]

n. [ Ideo- + -blast. ] (Bot.) An individual cell, differing greatly from its neighbours in regard to size, structure, or contents. [ 1913 Webster ]

n. [ Gr. me`ros part + -blast. ] (Biol.) An ovum, as that of a mammal, only partially composed of germinal matter, that is, consisting of both a germinal portion and an albuminous or nutritive one; -- opposed to holoblast. [ 1913 Webster ]

a. (Biol.) Consisting only in part of germinal matter; characterized by partial segmentation only; as, meroblastic ova, in which a portion of the yolk only undergoes fission; meroblastic segmentation; -- opposed to holoblastic. [ 1913 Webster ]

n. [ Meso- + -blast. ] (Biol.) (a) The mesoderm. (b) The cell nucleus; mesoplast. [ 1913 Webster ]

a. (Biol.) Relating to the mesoblast; as, the mesoblastic layer. [ 1913 Webster ]

n. [ Nemato- + -blast. ] (Biol.) A spermatocyte or spermoblast. [ 1913 Webster ]

n. [ Odonto- + -blast. ] [ 1913 Webster ]

1. (Anat.) One of the more or less columnar cells on the outer surface of the pulp of a tooth; an odontoplast. They are supposed to be connected with the formation of dentine. [ 1913 Webster ]

2. (Zool.) One of the cells which secrete the chitinous teeth of Mollusca. [ 1913 Webster ]

n. [ Osteo- + -blast. ] (Anat.) One of the protoplasmic cells which occur in the osteogenetic layer of the periosteum, and from or around which the matrix of the bone is developed; an osteoplast. [ 1913 Webster ]

n. [ Gr. &unr_; to wander + -blast. ] (Zool.) Any free-swimming gonophore of a hydroid; a hydroid medusa. [ 1913 Webster ]

n. [ Sarco- + -blast. ] (Zool.) A minute yellowish body present in the interior of certain rhizopods. [ 1913 Webster ]

n. Same as Spermoblast. [ 1913 Webster ]

n. [ Spermo- + -blast. ] (Physiol.) One of the cells formed by the division of the spermospore, each of which is destined to become a spermatozoid; a spermatocyte; a spermatoblast. [ 1913 Webster ]

n. [ Gr. spo`ggos sponge + -blast. ] (Zool.) One of the cells which, in sponges, secrete the spongin, or the material of the horny fibers. [ 1913 Webster ]

n. [ Gr. stato`s standing (i. e., remaining) + -blast. ] (Zool.) One of a peculiar kind of internal buds, or germs, produced in the interior of certain Bryozoa and sponges, especially in the fresh-water species; -- also called winter buds. [ 1913 Webster ]

☞ They are protected by a firm covering, and are usually destined to perpetuate the species during the winter season. They burst open and develop in the spring. In some fresh-water sponges they serve to preserve the species during the dry season. See Illust. under Phylactolaemata. [ 1913 Webster ]