A quantitative immunocytochemical approach to the analysis of type I cells in the cat carotid body.

Digital image analysis of immunostained semithin plastic sections indicates that experimentally induced changes in levels of transmitter-related reaction product in single cells fails to support the concept of clearly defined subsets of type I cells in the carotid body. This objective approach to the quantitation of staining product on a cell-by-cell basis appears to indicate that the observed changes are related to global shifts in the expression of a given neuronal marker throughout a single population of highly labile chemoreceptor elements.