Xenbase Image ID: 83519

Fig. 8. Cardiomyocytes retain an immature appearance after AGN 194301 treatment. Control embryos at stage 31 (A), stage 35 (B), stage 39 (C), and an AGN-194301-treated embryo (D) fixed at the same time as control sibling shown in C were immunolabeled and analyzed by confocal microscopy (10 RA antagonist embryos were analyzed; this embryo represents the trend seen). The black and white inset represents a compilation of all the optical sections of a z-series (60–70 4 μm sections) taken through the embryos as viewed with the muscle marker cardiac troponin I. The colored micrograph represents an optical thick section that is a subset of the inset (10 consecutive sections). Red = cardiac troponin I; green = F-22, flectin. The normal stage 31 embryo (A) shows the heart region after the left and right fields have fused but prior to tube closure. The troponin I staining reveals large columnar muscle cells characteristic of the stage. There is some flectin staining apparent on the basal side of the mesoderm as well as faint intracellular staining in the muscle cells of the left heart field in this particular subset of sections. At stage 35 (B), the heart has fused to form a tube and is beginning to undergo S-shaped looping. The muscle cells have lost their columnar appearance, and muscle striations are visible. Flectin is distributed in a subset of muscle cells as well as both the basal and apical surface of the endocardium. The normal stage 39 embryo heart (C) is viewed just prior to trabeculation; the striations more evident. The majority of the flectin staining is seen in the ECM. The 1 μM AGN-194301-treated embryos have unfused heart fields. They have not formed tubes but as they develop do not remain as flat sheets. The muscle cells have the columnar appearance of a less mature stage 31 embryo. The flectin staining has a temporal characteristic more similar to stage 39 with the majority of the localization in the ECM. Image published in: Collop AH et al. (2006) Copyright © 2006. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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