| 释义 |
placode Embryol.|ˈplækəʊd|
[ad. G. plakode (C. von Kupffer 1894, in Sitzungsber. der k. bayerischen Akad. der Wissensch. zu München (Math.-phys. Classe) XXIV. 57), f. Gr. πλακώδης laminated, flaky.]
A localized thickening of the ectoderm in a vertebrate embryo which contributes to the formation of a sensory organ or ganglial tissue.
1909Bailey & Miller Text-bk. Embryol. xvi. 459 In the case of the special sense organs there is an interesting tendency on the part of portions of the neural tube, either evaginations (optic vesicles, olfactory bulbs), or ganglia, to fuse with ectodermal thickenings (placodes) at the site of the future sense organs. 1927W. Shumway Vertebr. Embryol. vii. 186 Of the three sensory placodes, olfactory, optic, and otic, the optic placode is incorporated and invaginates with the neural plate so that the eye appears to originate from the brain. 1960Jrnl. Compar. Neurol. CXIV. 11/1 It now seems well established that the placodes provide a distinct cellular contribution to the developing ganglia of the V, VII, IX and X nerves in mammals, just as has long been accepted in fish and amphibians. 1977Proc. R. Soc. Med. LXX. 809/1 The otic placode appears at 21–24 days (Fig 10), and sinks below the surface as a vesicle which lies in undifferentiated mesenchyme. |