Cryo-scanning electron microscopy studies of pits in Pinus wallichiana and Mallotus japonicus.

摘要

Pits of a softwood (Pinus wallichiana) and a hardwood (Mallotus japonicus) were studied by Cryo-scanning electron microscopy (Cryo-SEM). The samples were chemically untreated and fully hydrated during freezing. Tori of P. wallichiana were frequently aspirated. It is not clear whether torus aspiration was caused by the freezing process or other factors during preparation. Aspirated tori had a turgid appearance. Off-center aspirated tori which did not completely cover the pit pore could be detected. The margo strands were usually quite large and fanned out into fibrillar structures at the pit border. Pit membranes of M. japonicus had a very granular appearance. No fibrillar structures, different layers or pores could be detected. The granular structures may have developed from a continuous layer covering the pit membrane during freezing. Cryo-SEM is discussed as a further suitable tool for obtaining novel information about the native state of pit membranes. Future studies are needed to validate whether all observed features represent characteristics of the native state.