Optimized Method for the Use of Polyethylene Glycol as Embedding Medium for Histological Studies

BACKGROUND: Polyethylene glycol (PEG) is a water-soluble polymer that can be used as tissue embedding medium for obtaining histological sections. It has been previously reported, that PEG provides good preservation of tissue morphological characteristics comparable to that of epoxy resins, and the resulting slices can be used for immunohistochemical studies. Several methods of using PEG in histological studies have been described in literature, but they are disorganized and generally difficult to reproduce. AIM: To evaluate tissue morphological characteristics and immunoreactivity in histological sections embedded in PEG. METHODS: We investigated the possibility and results of transferring collectible (archived) samples of murine (Mus musculus) and weatherfish (Misgurnus fossilis) embryos through PEG 1000 and PEG 1500, as well as the peculiarities of sectioning, sample spreading, mounting on slides, and staining. RESULTS: We compared the morphological characteristics of histological sections transferred through and embedded in PEG and paraffin wax. The advantages and disadvantages of using PEG for histological embedding were characterized. Immunohistochemical staining of sections using specific antibodies combined with chromogenic and fluorescent detection systems was performed. CONCLUSION: It has been demonstrated that PEG provides preservation of structural features of cells and intercellular substance, also having a sparing effect on protein epitopes in tissues.