Tissue distortion in three-dimensional reconstruction of wax or plastic embedded microscopic structures

Three-dimensional reconstruction at the light microscopic level depends on obtaining reliable serial sections without "distortion" i.e., expansion and compression during section preparation. We have studied the extent of such distortion in serial sections from paraffin and resin embedded blocks of brain, kidney, liver and lung, using an IBAS 2000 Image Analyser. We found that, taking the uncut block as 100%, the section area, perimeter and minimum diameter varied by no more than 8%, except for the lung sections which varied up to 14%. There was no progressive compression due to knife bluntening. Resin sections also varied up to 8% (16% for lungs) but in addition creasing was a problem. We conclude that, provided the serial sectioning is carefully standardised for block shape and orientation, floating out temperature and time, serial paraffin sections are more suitable for three dimensional reconstruction than resin sections.