The basement‐membrane‐like matrix of the mouse EHS tumor: II. Immunohistochemical quantitation of six of its components

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Abstract
The presence of six substances—laminin, type IV collagen, heparan sulfate proteoglycan, ontactin, fibronectin, and the amyloid P component—was investigated immunohistochemically in the matrix of the Engelbreth‐Holm‐Swarm (EHS) mouse tumor after it had been fixed in formaldehyde (with or without a brief preliminary glutaraldehyde fixation), embedded in Lowicryl K4M, and sectioned for processing through the protein A‐gold sequence. Enumeration of the number of gold particles per sequare micrometer of matrix sections demonstrated that the six substances were present in distinct amounts. The results for each substance were fairly consistent throughout the matrix in three experiments. Furthermore, the available evidence indicated that, with the exception of the amyloid P component, the substances were associated with the cord network of the tumor matrix. Finally, the use of a reconstituted basement membrane containing known amounts of laminin, type IV collagen, and heparan sulfate proteoglycan as a standard, led to the conclusion that, in the tumor matrix, the relative content of laminin to type IV collagen to the proteoglycan was in a ratio of 1:0.6:0.03, suggesting molar ratios of approximately 1:1:0.2, respectively.