Figure 3. Morphological and immunohistochemical comparison of Mn- and vehicle-exposed olfactory bulbs.

Images from a horizontal section showing the posterior part of two olfactory bulbs where they become adjacent along the midline (represented by the dashed line). The upper bulb in each image is ipsilateral to the intranasal vehicle instillation (Veh), while the lower bulb is ipsilateral to the intranasal 200 μg MnCl₂ instillation (Mn). Anterior is to the left and the vertex of the “V” shape is the midline of the mouse in all images. Rows A and B are all images from the same section, in which the green indicates spH fluorescence from ORN axons, blue indicates cell nuclei labeled with the nucleic acid stain DAPI, and red indicates AlexaFluor568 fluorescence from immunolabeled tyrosine hydroxylase. Rows C and D are images from a different section from the same mouse using the same colors except that red indicates AlexaFluor568 fluorescence from immunolabeled calbdindin-d28k. Rows B and D display the three possible color merged images from rows A and C, respectively, for comparison. No differences were observed between Mn-exposed and vehicle-exposed bulbs using any of these indicators. Note that while these images show a limited field of view of the medial edge of each bulb for display purposes, data quantification was performed across the entire bulb.