Basement membrane alterations after treatment with trypsin, hyaluronidase or collagenase

A transplantable rodent tumor producing multiple layers of basement membrane was used to study the effects of trypsin, hyaluronidase and collagenase on basement membranes. Treatment with trypsin resulted in an increase in the distance between adjacent lamellae and a loss of granular structures. Treatment with hyaluronidase separated basement membrane layers only in the outer lamellae, whereas collagenase resulted in extensively folded sheets which consisted predominantly of granules. From these findings it may be concluded that the granular structures represent the morphological equivalent of glycoproteins which are interlinked by a collagenous filamentous network. Hence, the BM represents a functional unit of proteoglycans, glycoproteins and collagen.