Structural components and characteristics of Reichert's membrane, an extra-embryonic basement membrane

This paper presents an analysis of mouse and rat Reichert's membrane, a thick basement membrane formed between the trophoblast and parietal endoderm cells of early mammalian embryos. When analyzed by polyacrylamide gel electrophoresis. Reichert's membranes from rat and mouse conceptuses appear simple and consist primarily of collagen and 4 noncollagenous glycoproteins of approximate Mr = 415,000, 245,000, 170,000, and 50,000. The proteins at 415,000 and 245,000 are similar in molecular weight to laminin and are immunoprecipitated by anti-laminin antiserum. The protein at 170,000 is co-precipitated with laminin and represents a novel form of a laminin-like protein, whereas the protein at 50,000 is unrelated to laminin. Using metabolic labeling experiments, it is shown that parietal endoderm cells synthesize these components and incorporate them into the matrix in organ cultures but do not degrade Reichert's membrane in the conditions used over a 6-day culture period. Evidence is presented that the high molecular weight collagenase-sensitive proteins (greater than 420,000) observed on polyacrylamide gel electrophoresis are due to lysyl oxidase-derived cross-links between Reichert's membrane components.