Anisotropy of apple parenchyma

Parenchyma of a range of apple varieties was either sectioned in a cryotome and observed under a light microscope, or freeze dried and viewed under a scanning electron microscope. The morphology of the material varied according to the direction from which it was viewed. This phenomenon, known as anisotropy, increased from the outside to the inside of the cortex. The periphery consisted of radially flattened or spherical cells (50 μ dia) with spherical intercellular spaces. Towards the interior the cells increased in size (300 μ dia) and were radially elongated, organised into radial columns. In between these columns were radially elongated spaces up to 3 mm long and 100–200 μ wide. The aspect ratio of the intercellular spaces increased almost linearly from outside to inside (1 to 9, depending on variety). The volume fraction of the cells similarly increased.