Figure 5. Glomerular development in Tnc −/− mice.

Coronal sections of Tnc+/+ and Tnc−/− medial olfactory bulb stained for the synaptic marker Vglut2 (green), the marker of OSN axons Ncam (red) and the nuclear marker DAPI (blue) at E17 (A, B), PND0 (C, D), PND2 (E, F) and PND4 (G, H). (A) In wildtypes at E17, VGlut2 staining is observed to be in a layer at the interface of the olfactory nerve layer (ONL) and the (DZ). Hemi-circular synaptic thickenings were observed in this layer (arrowheads) which are the immature glomeruli, or protoglomeruli, that are still fused and not separated from the ONL. (B) In null mice at E17, VGlut2 staining is also observed to be in a layer at the interface of the ONL and DZ, but considerably less dense than controls (c.f. panel A). Protoglomeruli were rarely, if ever observed. Some thickening in the layer of VGlut2 staining were occasionally observed (open arrowheads) however they were not hemi-circular and did not protrude into the DZ (c.f. arrowheads in panel A). (C) In wildtypes at PND0, glomeruli are discrete neuropil, separated from the ONL and forming their own layer, the glomerular layer (GL). (D). In null mice at PND0, glomeruli do not appear like the discrete structures seen in wildtypes. Rather, they have a more diffuse, “shaggy” appearance and are not separated from the underlying nerve layer. These structures also appear larger than control glomeruli. (E) In wildtypes at PND2, glomeruli appear to contain a high density of synapses. (F) In null mice at PND2, glomeruli appear more developed as compared to PND0. They appear more densely innervated (less “shaggy”) and separated from the ONL into a distinct GL. (G) In wildtypes at PND4, glomeruli appear to have increased in size as compared to PND2 (c.f. panel E). (H). In null mice at PND4 glomeruli appear indistinguishable from controls.

Scale bar = 100μm