Insoluble d-glucan-glycosaminoglycan complexes formed in aqueous ethanol solution

Disappearance of the cartilage interlacunar network during histological dehydration

The interlacunar network connects adjacent chondrocytes in rapidly growing cartilage and with anionic dyes stains more intensely than the surrounding matrix. The network is seen in fresh-frozen sections and sections treated with a variety of fixatives, dehydration agents and embedding media. The network is not seen after using such common dehydrating fluids as ethanol and acetone. Polyanionic glycosaminoglycans (GAG) are abundant in the cartilage matrix and it has been suggested that the network is an artifact caused by a rearrangement of the matrix GAG during histological processing. Extraction of GAG from neonatal rat cartilage with guanidine hydrochloride removes stainable extracellular matrix but not the interlacunar network. However, after extraction of GAG and immersion of the cartilage in either 50% or 100% aqueous ethanol or acetone, the network was no longer visible. The network apparently is not an artifact formed by soluble matrix GAG, but a real structure which is extracted, collapsed or otherwise destroyed during dehydration in ethanol or acetone.