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Embryogenesis of the phrenic nerve and diaphragm in the fetal rat
Author(s) -
Allan Douglas W.,
Greer John J.
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19970616)382:4<459::aid-cne3>3.0.co;2-1
Subject(s) - phrenic nerve , biology , spinal cord , diaphragm (acoustics) , anatomy , myogenesis , myocyte , embryogenesis , cord , embryonic stem cell , neuroscience , embryo , respiratory system , microbiology and biotechnology , medicine , loudspeaker , biochemistry , physics , surgery , gene , acoustics
The embryogenesis of the mammalian phrenic nerve and diaphragm continues to be poorly understood. The purpose of this study was to reexamine this general issue and resolve some long‐standing controversies. Specifically, we examined 1) the migratory path and the initial target for phrenic axons; 2) the relationship between the phrenic nerve and the primordial diaphragm during descent from the cervical to the thoracic spinal cord levels; and 3) the nature of the interaction between the progression of phrenic nerve intramuscular branching, myoblast and/or myogenic cell migration, and diaphragmatic myotube formation. We demonstrate that a leading group of “pioneering” phrenic axons migrate along a well‐defined track of neural cell adhesion molecule (NCAM)‐expressing and low‐affinity nerve growth factor (p75) receptor‐expressing cells to reach the primordial diaphragm, the pleuroperitoneal fold, at embryonic day (E) 13. During the next day of development, the phrenic nerve and the primordial diaphragm descend together toward the level of the thoracic spinal cord. By E14.5, intramuscular branching has commenced. There is a tight spatiotemporal correlation between the outgrowth of intramuscular phrenic nerve branches, the distribution of myoblasts and/or myogenic cells, and the formation of myotubes within the developing diaphragm, implicating intimate mutual regulation. J. Comp. Neurol. 382:459‐468, 1997. © 1997 Wiley‐Liss Inc.