Figure 1
From: Zebrafish crypt neurons project to a single, identified mediodorsal glomerulus
TrkA-like immunoreactivity co-localizes with S100-like immunoreactivity and crypt neuron morphology.
(a) TrkA-like immunoreactivity (green) is seen in a sparse population of ovoid cells in horizontal sections of olfactory epithelium (fixed); the inset shows another TrkA-labeled neuron at higher magnification. (b) Enlargement of several TrkA-labeled cells from another section showing the typical ovoid shape of crypt neurons; the inset shows another TrkA-labeled neuron at 1000× magnification, enabling visualization of the initial axon segment. (c) Double labeling with anti-S100 antibody (red) and anti-TrkA antibody (green) in fixed tissue shows TrkA labeling restricted to a subset of cells with S100-like immunoreactivity. Note the difference in morphology between double-labelled cell (yellow) and TrkA-/S100+ cells (red). (d) In fresh-frozen tissue S100-like immunoreactivity and TrkA-like immunoreactivity label the same, sparse population of globose cells. (e) Quantification of overlap between S100 and TrkA-staining, values given are mean +/− SEM. TrkA-positive cells show nearly complete overlap with S100-positive cells in fresh-frozen tissue (p = 0.2, Student's t-test, two-sided, unpaired), where S100 label is specific for crypt neurons6, but constitute only a minority of S100-positive cells in fixed tissue (p < 10−12, Student's t-test, two-sided, unpaired), in which S100 antibody labels many more cells besides crypt neurons6. (f, g) The ratio of vertical to horizontal diameter, ‘diameter ratio (v/h)’, was measured for TrkA- and S100-labeled cells under standard histological conditions (‘fixed’) and in fresh frozen tissue (‘fresh’). (f) histogram, (g) empirical cumulative distribution function (ECDF) of the unbinned distributions. Note the extreme similarity of the distribution for TrkA in both conditions with the distribution for S100 in fresh-frozen tissue and the drastic difference (p < 10−6, Kolmogorov-Smirnov test, cf. SI Table 1) to the distribution of S100-labeled cells under standard histological conditions (‘fixed’). (h), (i) The relative height of labeled cells within the olfactory lamella was compared for TrkA- and S100-labeled cells under standard histological conditions, i.e. in fixed tissue. (h) histogram, (i) empirical cumulative distribution function (ECDF) of the unbinned distributions. The difference between distributions was highly significant (Kolmogorov-Smirnov test, p < 0.0002). Scale bars 80 μm for (a) and 10 μm for (b–d), respectively.
