M. Weichselbaum et Mp. Sparrow, A confocal microscopic study of the formation of ganglia in the airways offetal pig lung, AM J RESP C, 21(5), 1999, pp. 607-620
Citations number
36
Categorie Soggetti
da verificare
Journal title
AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY
Fetal airway smooth muscle contracts to neural stimulation from early gesta
tion. This study aimed to document the development of the nerves and gangli
a within the bronchial tree of the fetal pig lung as the structural correla
tes for this function. The formation of these structures during lung develo
pment (pseudoglandular stage, canalicular stage, and saccular stage) was fo
llowed through to the postnatal period, using antibodies to protein gene pr
oduct 9.5, a nonspecific nerve marker; synaptic vesicle protein 2, a marker
of synaptic vesicle membranes; and neurofilament, a marker of filaments in
the neuronal cytoskeleton. Glial cells were stained for glial fibrillary a
cidic protein (GFAP) and S-100, and the airway smooth muscle for a-actin. W
hole mounts of the bronchial tree were imaged using confocal microscopy. Th
e formation of ganglia commences in the pseudoglandular stage with patches
of neuroblasts in the wall of the epithelial tubules. These ganglionic prec
ursors are supplied with an abundance of nerve trunks and fibers that arise
from the vagus and extend to the growing tips of the airways. These trunks
show profiles of Schwann cells. As the airways grow, the ganglionic precur
sors condense at the nerve junctions. Nerve bundles in trunks and neurons i
n ganglia become increasingly enveloped by GFAP-positive sheaths. From midt
erm onward (canalicular stage), ganglia contain cholinergic neurons. In the
third trimester (saccular stage) and postnatally, ganglia further increase
in size and contain mainly nerve fibers in the center. Thus, neural tissue
is a dominant feature of the primordial lung, which is enveloped by nerves
and ganglia through gestation into postnatal life.