Figure 8. Ca²⁺ transients in and characteristics of Dogiel Type II neurons.

High power imaging (×40 and 60 objective) of Ca²⁺ activity in Dogiel Type II neurons. A, local stimulation (puffs of nitrogen applied to the mucosa) evoked a brief Ca²⁺ transient in two neurons (N1 and N2) that appeared to have Dogiel Type II morphology. These responses were mimicked in the processes (S1, S2 and S3) that ramified throughout the ganglia and appeared to emanate from these neurons. B, most mitotracker +ve neurons (left hand panel) appeared to also contain calbindin (right hand panel). Neurons were considered positive for either mitotracker or calbindin if they had an average pixel intensity greater than 150 (8-bit scale). Mitotracker +ve and calbindin +ve neurons had a similar area and shape and were longer and wider than neurons that were considered to be negative for these labels. White arrows indicate mitotracker stained neurons and calbindin +ve neurons; open arrows indicate mitotracker stained neurons but calbindin −ve neurons. C, analysis of the average intensities of calbindin +ve versus mitotracker +ve labelled neurons reveals that positive neurons are readily identifiable, and, given the two labels, are statistically more likely to be either co-labelled or negative for both substances. Dotted line respresents the threshold for a labelled neuron. D, analysis of the size of calbindin +ve, mitotracker +ve, and −/− neurons demonstrates that neurons that label positive for either or both substances have significantly larger average soma areas (558 μm², to 462 μm², to 165 μm², respectively), height (35 μm, to 30 μm, to 16 μm, respectively), and width (24 μm, to 22 μm, to 13 μm, respectively).