FIB-SEM imaging of calbindin GSSP-labeled Purkinje cells. (A-B) A single
block-face image from an FIB-imaged stack, showing a fragment of the
Purkinje cell layer (S, Purkinje cell soma) with GSSP-positive areas in
somata of Purkinje cells (white box) and in dendrites (dds; black box).
(B) Higher magnification images of areas highlighted in 3A. Top,
fragment of a body of a Purkinje cell showing calbindin immunolabeling
as distinct round deposits that are darker than any elements of cellular
ultrastructure, white arrowheads. Bottom, fragment of a dendrite of a
Purkinje cell, rotated image. Note the highly contrasted, regularly
shaped deposits corresponding to calbindin immunoreactivity. (C-D) The
size and density of GSSP particles allows to easily follow and segment
immunopositive structures. Individual GSSP particles shown in yellow and
manual segmentation of a Purkinje cell dendritic segment in purple (dd).
Dendrite indicates the same dendrite in 3A, 3B (bottom), 3C, and 3D.
Imaging was performed using a ZEISS Auriga Crossbeam FIB-SEM. Scale bar
= 200 µm. Abbreviations: FIB-SEM, focused ion beam–scanning electron
microscopy; GSSP, gold-substituted silver peroxidase.