Cryostat tissue printing: an improved method for histochemical and immunocytochemical localization in soft tissues.

A modification of a previously described tissue print technique has been developed in which soft tissues are frozen and sectioned in a cryostat prior to direct collection on nitrocellulose or nylon membranes. The inexpensive embedding technique described here allows accurate orientation of specimens prior to mounting, and mounted material may be stored easily after initial sectioning for future reexamination. Standard hand tissue prints of soft specimens exhibit tissue distortion and uneven delivery of material to the membrane, which limits resolution and makes interpretation difficult. Cryostat sections retain tissue fragments in their original arrangement relative to each other during printing and deliver a consistent and quantitative amount of material from all parts of the specimen. The cryostat tissue print technique is applied here to immature floral buds, demonstrating the tissue-level histochemical localization of beta-glucuronidase in transgenic plants and immunolocalization of a novel protein present only in mutant plants. This modified technique is applicable for examining both plant and animal tissues.