Chamber-Specific Morphometry and Quantitative Cardiac Histology in the Broad-Snouted Caiman (Caiman latirostris)

Quantitative cardiac morphology remains poorly documented in crocodilians. Hearts from four commercially reared male Caiman latirostris were examined by gross morphometry, histology, stereology, reticulin staining and Masson's trichrome. Relative heart mass averaged 0.125% of body mass. The left ventricular wall was numerically thicker than the right. Cardiomyocyte volume density and cross-sectional area varied among chambers, whereas collagen-positive area was greater in the right ventricle. Pulmonary arterial walls were markedly thinner than the systemic aortae, and the left pulmonary arterial wall was thicker than the right. These findings extend quantitative cardiac reference data for this species.