| 释义 |
placentation|plæsənˈteɪʃən|
[a. F. placentation, f. placenta: see -ation.]
1. Zool. The formation and disposition of the placenta in the uterus.
1871Trans. R. Soc. Edin. XXVI. 486 Of the mammals, the placentation of which most commonly comes under observation, the sow and the mare also offer well-known examples of the diffused form of placenta. 1880Huxley in Times 25 Dec. 4/1 The non-prehensile pes would separate it from the former, and the placentation from the latter group. 1971J. Z. Young Introd. Study Man xxx. 423 The sexual cycle and placentation of lemurs are interestingly different from those of other primates.
2. Bot. The disposition or arrangement of the placenta or placentas in the ovary.
1760J. Lee Introd. Bot. iii. xi. (1765) 197 By Placentation is meant the Disposition of the Cotyledons at the Time when the Seed is beginning to grow. 1848Lindley Introd. Bot. (ed. 4) I. 389 The placentation of Water-lilies..Broom⁓rapes..and Butomads, is equally at variance with the central theory. 1872Darwin Orig. Spec. (ed. 6) I. vii. 174 Instances of both marginal and free central placentation. |