Cover: (Left panel ) Montage of the left distal stem bronchus from a gestational week (GW) 8 (90 g body weight) fetal pig stained with protein gene product (PGP) 9.5 for nerves (green) and -actin for smooth muscle (red ). The numerous ganglia are now more spherical in shape. (Top central panel ) Magnified view of a field of the bronchus shown in the former panel (circled area). A large nerve trunk that is accompanied by blood vessels runs longitudinally along the airway. A ganglion is situated to the right of the trunk, with nerve bundles radiating out over the smooth muscle. These nerve bundles give rise to a dense network of thinner fibers that descend to the airway smooth muscle. (Top right panel ) High-power view of a single optical section through the ganglion shown in the previous panel. The trunk shows dark cellular profiles that are most likely Schwann cells. The vasculature exhibits extensive branching around the ganglion. The neurons on the perimeter of the ganglion show cytoplasmic and nuclear PGP 9.5 immunoreactivity, whereas the cells in the center of the ganglion exhibit staining of a cytoplasmic rim only, with little or no nuclear staining. (Bottom right panel ) High-power view of a single optical section through a ganglion from the distal stem bronchus from a GW 8.5 (110 g body weight) fetal pig, stained with PGP 9.5. The cell bodies are, on average, 11 µm in diameter. Nucleoli can be identified as dark holes of 2 to 3 µm diameter within the nuclear regions of the neurons. The inside of the ganglion shows many dark exclusions that are most likely profiles of blood vessels and satellite cells. The adjacent nerve trunk comprises many folded bundles of fibers that are separated from each other. For more information, see article by Weichselbaum and colleagues 607.
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