Application of frozen thin sectioning immunogold staining to the study of the developing neuroepithelial basal lamina

In order to examine the deposition of basal lamina components in the developing neuroepithelium, a technique for frozen thin sectioning and immunogold staining of early embryonic tissue was developed. Different fixatives and buffer systems were evaluated to determine which best retained immunoreactivity and satisfactory ultrastructure of day 9 and 10 mouse embryos. Fixation in sodium phosphate and sodium bicarbonate buffers did not retain antigenicity, and incubations in TBS (trishydroxymethyl-aminomethane buffered saline) in an effort to 'restore' immunoreactivity were similarly unsuccessful. Fixation in sodium cacodylate buffer, however, did retain the antigenicity of basal lamina components; the pattern of type IV collagen and laminin distribution was clearly determined. These results represent the first report of on-grid immunocytochemistry of early embryonic material.