Open AccessComparison of the histology and stiffness of ventricles in Anura of different habitats
Author(s) -
Megumi Ito,
Yoshihiro Ujihara,
Shukei Sugita,
Masanori Nakamura
Publication year - 2021
Publication title -
journal of biological physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.318
H-Index - 46
eISSN - 1573-0689
pISSN - 0092-0606
DOI - 10.1007/s10867-021-09579-4
Subject(s) - biology , sarcomere , cardiac ventricle , histology , vertebrate , anatomy , xenopus , left ventricles , zoology , habitat , amphibian , extant taxon , ecology , evolutionary biology , microbiology and biotechnology , myocyte , medicine , genetics , ventricle , gene
Vertebrate hearts have undergone marked morphological and structural changes to adapt to different environments and lifestyles as part of the evolutionary process. Amphibians were the first vertebrates to migrate to land. Transition from aquatic to terrestrial environments required the ability to circulate blood against the force of gravity. In this study, we investigated the passive mechanical properties and histology of the ventricles of three species of Anura (frogs and toads) from different habitats, Xenopus laevis (aquatic), Pelophylax nigromaculatus (semiaquatic), and Bufo japonicus formosus (terrestrial). Pressure-loading tests demonstrated stiffer ventricles of P. nigromaculatus and B. j. formosus compared X. laevis ventricles. Histological analysis revealed a remarkable difference in the structure of cardiac tissue: thickening of the compact myocardium layer of P. nigromaculatus and B. j. formosus and enrichment of the collagen fibers of B. j. formosus. The amount of collagen fibers differed among the species, as quantitatively confirmed by second-harmonic generation light microscopy. No significant difference was observed in cardiomyocytes isolated from each animal, and the sarcomere length was almost the same. The results indicate that the ventricles of Anura stiffen during adaptation to life on land.