Labeling of structural elements at the ventral plasma membrane of fibroblasts with the immunogold technique.

We investigated the organization of two structural elements (microfilaments and clathrin coated structures) at the ventral plasma membrane in fibroblasts. The methods employed included exposure of the inner face of the ventral plasma membrane by lysis-squirting, labeling the exposed structures with specific antibodies conjugated with colloidal gold, and platinum-carbon replica techniques. The results demonstrate that this regimen combines good ultrastructural preservation with unambiguous identification of structural elements associated with the plasma membrane. This method is therefore reliable and can be generally used to explore in detail the ultrastructural organization of the plasma membrane.