Morphometric, quantitative, and three-dimensional analysis of the heart muscle fibers of old rats: Transmission electron microscopy and high-resolution scanning electron microscopy methods

This research investigated the morphological, morphometric, and ultrastructural cardiomyocyte characteristics of male Wistar rats at 18 months of age. the animals were euthanized using an overdose of anesthesia (ketamine and xylazine, 150/10 mg/kg) and perfused transcardially, after which samples were collected for light microscopy, transmission electron microscopy, and high-resolution scanning electron microscopy. the results showed that cardiomyocyte arrangement was disposed parallel between the mitochondria and the A-, I-, and H-bands and their M- and Z-lines from the sarcomere. the sarcomere junction areas had intercalated disks, a specific structure of heart muscle. the ultrastructural analysis revealed several mitochondria of various sizes and shapes intermingled between the blood capillaries and their endothelial cells; some red cells inside vessels are noted. the muscle cell sarcolemma could be observed associated with the described structures. the cardiomyocytes of old rats presented an average sarcomere length of 2.071 +/- 0.09 mu m, a mitochondrial volume density (Vv) of 0.3383, a mitochondrial average area of 0.537 +/- 0.278 mu m2, a mitochondrial average length of 1.024 +/- 0.352 mu m, an average mitochondrial cristae thickness of 0.038 +/- 0.09 mu m and a ratio of mitochondrial greater length/lesser length of 1.929 +/- 0.965. of the observed mitochondrial shapes, 23.4% were rounded, 45.3% were elongated, and 31.1% had irregular profiles. in this study, we analyzed the morphology and morphometry of cardiomyocytes in old rats, focusing on mitochondria. These data are important for researchers who focus the changes in cardiac tissue, especially changes owing to pathologies and drug administration that may or may not be correlated with aging. Microsc. Res. Tech., 2013. (C) 2012 Wiley Periodicals, Inc.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The Faculty of Medicine, Fukuoka UniversityUniv São Paulo, Dept Surg, Fac Vet Med & Anim Sci, BR-05508900 São Paulo, BrazilUniv São Paulo, Dept Anat, Inst Biomed Sci, BR-05508900 São Paulo, BrazilFed Univ Para, Inst Biol Sci, Lab Invest Neurodegenerat & Infect, Univ Hosp Joao de Barros Barreto, BR-66059 Belem, Para, BrazilFukuoka Univ, Sch Med, Dept Anat, Fukuoka 81401, JapanUniversidade Federal de São Paulo, Dept Morphol & Genet, São Paulo, BrazilUniv São Paulo, Fac Dent, Dept Morphol Stomatol & Physiol, BR-14049 Ribeirao Preto, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, São Paulo, BrazilWeb of Scienc