Apoptosis and proliferation in developing, mature, and regressing epibranchial placodes

Epibranchial placodes and rhombencephalic neural crest provide precursor cells for the geniculate, petrosal, and nodose ganglia. In chick embryos and in Tupaia belangeri, apoptosis in rhombomeres 3 and 5 helps to select premigratory precursor cells and to segregate crest cell streams derived from th...

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Bibliographic Details
Published in:Developmental biology 2005-02, Vol.278 (1), p.86-102
Main Authors: Washausen, Stefan, Obermayer, Bastian, Brunnett, Guido, Kuhn, Hans-Jürg, Knabe, Wolfgang
Format: Article
Language:English
Subjects:
3-D reconstruction
Animals
Apoptosis
Cell Proliferation
Cranial nerves
Development
Ectoderm - cytology
Epibranchial placodes
Hindbrain
Image Processing, Computer-Assisted
Mammal
Morphogenesis
Nervous System - cytology
Nervous System - embryology
Neural crest
Neural Crest - cytology
Neural Crest - embryology
Proliferation
Tupaia - anatomy & histology
Tupaia - embryology
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Summary:Epibranchial placodes and rhombencephalic neural crest provide precursor cells for the geniculate, petrosal, and nodose ganglia. In chick embryos and in Tupaia belangeri, apoptosis in rhombomeres 3 and 5 helps to select premigratory precursor cells and to segregate crest cell streams derived from the even-numbered rhombomeres. Much less is known about the patterns and functions of apoptosis in epibranchial placodes. We found that, in Tupaia belangeri, combined anlagen of the otic placode and epibranchial placode 1 transiently share a primordial low grade thickening with post-otic epibranchial placodes. Three-dimensional reconstructions reveal complementary, spatially, and temporally regulated apoptotic and proliferative events that demarcate the otic placode and epibranchial placode 1, and help to individualize three pairs of epibranchial placodes in a rostrocaudal sequence. Later, rostrocaudal waves of proliferation and apoptosis extend from dorsal to ventral parts of the placodes, paralleled by the dorsoventral progression of precursor cell delamination. These findings suggest a role for apoptosis during the process of neuroblast generation in the epibranchial placodes. Finally, apoptosis eliminates remnants of the placodes in the presence of late invading macrophages.
ISSN:0012-1606
1095-564X
DOI:10.1016/j.ydbio.2004.10.016