Fig. 2.

Retrograde labeling identifies commissural GCs. A) Experimental design (also see main text). B) Confocal images show retrogradely labeled, EGFP+ cells in GC layer (GCL) in the left hippocampus after ipsilateral saline or KA injection. Note the (i) presence of retrogradely labeled mossy cells (which also project to the contralateral hippocampus) and their axons in the inner molecular layer after saline injection and (ii) lack of mossy cells and axons and GCL dispersion (these are known effects of KA) after KA injection; retrogradely labeled CA3 pyramidal cells (which also project to the contralateral hippocampus) are visible in both images. C and D) Confocal image and morphological reconstruction of retrogradely labeled commissural GCs after saline (cell S1 is also shown in B, left) and KA injection (cell KA1–8 are also shown in B, right), respectively. E) Plot shows the number of retrogradely labeled commissural GCs in the ipsilateral (with respect to saline or KA injection) left hippocampus. Each data point represents the total number of commissural GCs detected in one animal. Data represent mean ± SEM (Mann–Whitney test). F) Plot shows the septo-temporal distribution of retrogradely labeled commissural GCs after ipsilateral saline and KA injection. For averaging, individual distributions were aligned to the ipsilateral (saline and KA) injection sites.