Changes in synaptic transmission but not odorant detection in the olfactory system of newborn <i>Dmxl2-</i>knockout mice.

(A) EOG peak amplitudes in response to various odorants were recorded at P0 in newborn HTZ (black dots) and KO (red dots) pups. No significant differences were found, demonstrating the ability of the olfactory mucosa of newborn Dmxl2 KO mice to detect odorants (Fisher-Pitman permutation test). (B) Cumulative traces of HTZ (black) and KO (red) EOG responses to hexanal diluted 1:10 in mineral oil. (C) Immunodetection of c-Fos in HTZ and KO olfactory bulbs after odorant stimulation. C-Fos-positive neurons (white arrowheads) were more abundant in HTZ than in KO olfactory bulbs (gl: glomerular cell layer; pe: plexiform external cell layer; mi: mitral cell layer). (D) Quantification of c-Fos activation and neuron density (DAPI signal) in the olfactory bulb. Specific c-Fos (left panel) and DAPI (right panel) signals were defined on the basis of the size and shape of the area stained. These signals are reported relative to the area of the plexiform external region and glomerular cell layers. Median values were plotted, and statistical analyses were performed with Fisher-Pitman two-sample exact permutation tests (pValue<0.05). Significant differences are indicated by an asterisk (pValue = 0.023).