Distribution of substance P-immunoreactive structures in the developing cat carotid body.

The distribution of substance P immunoreactivity in the cat carotid body was examined at 4 different stages of development. Although substance P-immunoreactive fibers were present in the carotid body from before birth through to adulthood, glomus cells did not display substance P-immunoreactivity until the period between birth and 6 weeks postnatally. The time course of these morphological differences in substance P distribution in the cat carotid body parallel the maturational changes in the hypoxic ventilatory response, suggesting that substance P may play a role in these changes.