Proportions of OLM and HS cells in somatostatin-positive interneurons of CA1 str. oriens.

A1-3: Confocal laser-scanning microscope image of a Cre-dependent AAV-eYFP tracer injection site in the CA1 str. oriens of a Chrna2-Cre mouse. The section was double-labeled for somatostatin and eYFP, and 49.1%, 42%, and 37.9% of somatostatin-positive cells were eYFP-positive OLM cells in 3 mice, respectively. B1-3: Confocal laser-scanning microscope image from CA1 str. oriens in a mouse with FluoSpheres-injection into the medial septum. Yellow-green fluorescent microbeads were retrogradely transported into the somata of HS cells, whereas somatostatin was labeled by immunocytochemistry; 9.5%, 8.1%, and 7.5% of somatostatin-positive cells were tracer-containing HS cells in 3 mice, respectively. Yellow arrowheads indicate double-labeled cells, whereas red arrowheads show somatostatin-positive cells that did not contain tracer. Scale bar: 50 μm.

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