According to the manner of tissue preparation, immunocytochemical techniques are broadly divided into two groups, nonembedding and embedding techniques. In the nonembedding techniques, there are immunoferritin (Tokuyasu and Singer, 1976) and protein A-gold techniques (Geuze et al., 1981) using ultracryosections, and surface labelling of freeze fracture preparations (Pinto da Silva and Branton, 1970). According to the step by which the immunological reaction is performed, the embedding techniques could be further divided into two groups, pre-embedding and post-embedding techniques. In the former, immunoperoxidase (Nakane and Pierce, 1967) and immunoferritin (Willingham et al., 1981, 1984) were mainly used while, in the latter, the protein A-gold probes were primarily employed (Roth et al., 1978).