| 释义 |
‖ pronucleus Biol.|prəʊˈnjuːklɪəs|
[mod.L. (E. van Beneden), f. Gr. πρό, pro-2 + nucleus.]
A primitive or prior nucleus; in Zool. the nucleus of a spermatozoön or of an ovule, before these unite to form the definitive nucleus of the fertilized ovum; in Bot. the nucleus of a gamete, which, by coalescing with another of the opposite sex, forms the germ nucleus.
1880Athenæum 25 Dec. 868/3 In this egg,..shortly before impregnation, a clear nucleus is formed, round which the protoplasm of the egg becomes radiately striated. This is known as the female pronucleus. 1882Vines Sachs' Bot. 524 One of these is the nucleus of the oosphere, and may be termed the ‘female pronucleus’; the other appears to have passed into the oosphere from the pollen-tube, and is the ‘male pronucleus’ (spermakern). These two nuclei coalesce to form the definitive nucleus of the oospore. 1888Rolleston & Jackson Anim. Life Introd. 25 The two pronuclei approach each other, and the granules of the surrounding protoplasm are arranged round each of them, so as to form a star or aster with a pronucleus as a centre. |