|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
THE DETERMINATION OF THE AUDITORY PLACODE IN THE CHICK
1 Strangeways Research Laboratory and Sub-Department of Experimental Zoology, Cambridge
1. The presumptive ear ectoderm, removed from its normal site and transplanted to the amnio-cardiac vesicle, does not develop into an otic placode unless it comes from an embryo with more than nine pairs of somites.
2. The ectoderm which grows over the place from which the presumptive ear ectoderm is removed is induced to form an otic placode, the size of the placode being smaller the older the embryo at the time of operation.
3. If the wall of the neural tube, including the neural crest, is removed from the region of the ear in embryos younger than the nine-somite stage, an ear may nevertheless be formed. Since the ear ectoderm at this stage is not capable of differentiating when isolated, this result shows that inducing agencies other than the neural material are active at this stage. In some of the operated embryos, the acoustico-facialis ganglion was completely lacking, so this structure cannot be the sole organizer of the ear, as Szepsenwol suggested.
4. If both the wall of the neural tube and the presumptive ear ectoderm are removed, no ear is formed even in stages younger than the nine-somite stage, so that it appears that the non-neural inducing agents are more effective when working on presumptive ectoderm of this age than when working on non-presumptive ectoderm. This suggests that the ear ectoderm is beginning to be determined some time before it acquires the capacity for independent differentiation.
5. The wall of the neural tube, from the ear region, can induce a small ear when grafted under the ectoderm of the anterior part of the head.
6. The evidence suggests that the induction of the ear in normal development is due to the combined action of several structures, of which the wall of the neural tube, and the tissues derived from it (ganglia), is one but not the only one.
Submitted on November 10, 1936
This article has been cited by other articles:
|
|
 |
|
  D. Liu, H. Chu, L. Maves, Y.-L. Yan, P. A. Morcos, J. H. Postlethwait, and M. Westerfield Fgf3 and Fgf8 dependent and independent transcription factors are required for otic placode specification Development, May 15, 2003; 130(10): 2213 - 2224. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S.-J. Kwak, B. T. Phillips, R. Heck, and B. B. Riley An expanded domain of fgf3 expression in the hindbrain of zebrafish valentino mutants results in mis-patterning of the otic vesicle Development, March 13, 2003; 129(22): 5279 - 5287. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. S. Solomon, T. Kudoh, I. B. Dawid, and A. Fritz Zebrafish foxi1 mediates otic placode formation and jaw development Development, March 1, 2003; 130(5): 929 - 940. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. S. Solomon and A. Fritz Concerted action of two dlx paralogs in sensory placode formation Development, January 7, 2002; 129(13): 3127 - 3136. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Groves and M Bronner-Fraser Competence, specification and commitment in otic placode induction Development, January 8, 2000; 127(16): 3489 - 3499. [Abstract] [PDF]
|
|
|
|
|
|
H Herbrand, S Guthrie, T Hadrys, S Hoffmann, H. Arnold, S Rinkwitz-Brandt, and E Bober Two regulatory genes, cNkx5-1 and cPax2, show different responses to local signals during otic placode and vesicle formation in the chick embryo Development, January 2, 1998; 125(4): 645 - 654. [Abstract] [PDF]
|
|
|
|
|
|
M. Stark, J Sechrist, M Bronner-Fraser, and C Marcelle Neural tube-ectoderm interactions are required for trigeminal placode formation Development, January 11, 1997; 124(21): 4287 - 4295. [Abstract] [PDF]
|
|
|
|
|
|
K. Vogel and A. Davies Heterotopic transplantation of presumptive placodal ectoderm changes the fate of sensory neuron precursors Development, January 9, 1993; 119(1): 263 - 276. [Abstract] [PDF]
|
|
