Fig. 1.

Granule cell filled with biocytin in vivo. The cell was first developed for biocytin and photographed, and the image was fused with the cresyl violet-stained image of the same section. Arrow indicates mossy fiber;white arrowheads indicate local collaterals in the hilar region. m, Molecular layer; g, granule cell layer; h, hilus; CA3, pyramidal layer of CA3c. Top inset, Current–voltage responses of the granule cell to hyperpolarizing (−0.8, −0.6, and −0.4 nA) and depolarizing (0.7 and 0.8 nA) current steps. Bottom inset, High magnification of a mossy terminal (arrow) in the hilar region. Double arrowhead indicates filopodial extension; white arrowheads indicate small en passant and drumstick-like boutons. Scale bar, 10 μm.