Distribution of laminin, collagen type IV, collagen type I, and fibronectin in chicken cardiac jelly/basement membrane.

Light microscopic immunolabeling studies were designed to identify and locate structural components within the cell-free extracellular matrix which lies between the embryonic endocardial and myocardial tubes. Affinity-purified antibodies were used to examine stage 15-22 embryonic chicken hearts. Specimens were immunolabeled by using three different methodologies: 1) postembedding labeling of 10 microns cryostat sections, 2) preembedding labeling (en bloc) of whole hearts, and 3) postembedding labeling of ethanol/acetic acid-fixed paraffin sections. Our results establish the spatial distribution of collagen type I and demonstrate for the first time the presence of collagen type IV and laminin in the myocardial-basement-membrane/cardiac jelly.