ON THE 3-DIMENSIONAL RECONSTRUCTION OF TH E INTERCELLULAR SYSTEM IN APPLE FRUIT

The intercellular system in plants provides for the gas exchange of th e cells, and it forms an internal atmosphere in the tissue. The invest igations aimed to demonstrate by three-dimensional reconstruction of s erial sections how the intercellular system of apple fruits is interco nnected and if there is a direct contact over stomata and/or lenticell s to the surface and the external atmosphere of the fruit. Therefore, plastic embedded material of hypodermis, cortex and core was sectioned at 5 mum, stained with hematoxylin and chrysoidin, and processed to p ermanent slides. By digital image processing the serial sections were used for three-dimensional reconstruction of the structure of the inte rcellular system in different tissue areas and under lenticells. The t hree-dimensional reconstructions revealed that the intercellulars form a system which is interconnected, especially in the cortex area. In t he core area the frequency of connections is not as high since the per centage of intercellular volume is lower in this area. In the hypoderm is the intercellular spaces end at the latest at the epidermal cells, i.e. they have no direct contact to the fruit surface. But these space s have again connection to the intercellular system of the cortex. How ever, under lenticells a direct connection between fruit surface and c ortex could be reconstructed. The investigations confirmed the hypothe sis that the intercellulars of apple fruit form an interconnected syst em. Furthermore a direct connection of the intercellular system over t he lenticells to the external atmosphere of the fruit could be demonst rated.