Effect of histologic preparation on the cross-sectional area of arterial rings

Histometric studies are useful for correlating mechanical properties of tissues with morphological characteristics. However, fixation and embedding can cause volume changes and may cause tissue distortion. This study examined 24 rings of unpressurized arteries fixed with formalin, glutaraldehyde, or McDowell's solution and then embedded in paraffin or glycol methacrylate. A ring of each artery was also studied in the fresh state. The tissues were projected at 22X magnification and cross-sectional areas were measured. The dimensions of the fixed rings were compared with that of the fresh tissue. Results showed that embedding with paraffin produced 19-25% shrinkage with all three fixatives, whereas embedding with glycol methacrylate produced 4 to 13% volume expansion with the three fixatives. The least volume expansion occurred with McDowell's solution fixation (4%) and glutaraldehyde fixation (8%). These findings suggest that, when performing histometric studies, one should consider using glycol methacrylate for embedding in order to cause the least volume change.