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Images in Cardiovascular Medicine
Connective Tissue Skeleton of the Human Heart
A Demonstration by Cell-Maceration Scanning Electron
Microscope Method
Marcos A. Rossi, MD; Monica A. Abreu, BS; Lı́gia B. Santoro, BS
T
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he stroma of the heart maintains the structure of the
myocardium, determining tissue tensile strength and stiffness.1 In addition, it contributes to ventricular function
through the transmission of myocyte-generated force to the
atrial and ventricular chambers and to the relengthening of
myocytes in diastole.2 The three-dimensional configuration
of cardiac collagen has been determined by scanning electron
microscopy3-5: the epimysium envelops the entire cardiac
muscle; the perimysium, which is an extension of the
epimysium, serves to enwrap groups of myocytes; and the
endomysium, as final arborization of the perimysium, supports and connects individual cells. The endomysial weave
envelops each individual myocyte and is connected to
adjacent myocytes by lateral struts.
Because this knowledge was obtained through studies on
whole fixed myocardial tissue without removal of its nonfibrous elements, we attempted to dissolve the cellular elements and leave behind a noncollapsed matrix, aiming for a
better three-dimensional view. For this, we used a modification of the NaOH maceration technique reported by
Ohtani.6 This method was reported to be able to remove
cellular elements much more effectively than any other
method. Small fragments, 103533 mm in size, of the
anterior wall at the midventricular region were obtained
from three human hearts, weighing between 300 and 350 g,
without any pathological changes. All samples were fixed in
10% neutral formalin. After being rinsed in distilled water,
the specimens were immersed in a 10% NaOH solution for
4 to 6 days at room temperature and then rinsed in distilled
water until they became transparent. Then they were immersed in 1% tannic acid for 4 hours. Subsequently, the
specimens were rinsed in distilled water overnight, rinsed,
post-fixed in 1% osmium tetroxide for 2 hours, dehydrated in
graded concentrations of ethanol, sectioned transversely or
longitudinally with a very sharp, clean blade under a dissecting microscope, freeze-dried, coated with gold, and observed
under a Zeiss 940-A scanning electron microscope.
The figure clearly shows, for the first time, the threedimensional architecture of collagen fibrils in human myo-
Connective tissue skeleton of human heart sectioned transversely. Its organization is quite similar to a honeycomb. The
perimysium (P) envelops groups of myocytes. The endomysium, as final arborization of the perimysium, supports and
connects individual cells. The endomysial weave (W) envelops
each individual myocyte and is connected to adjacent myocytes by lateral struts (s) presenting branches of variable size
and extension. The range of length and diameter of these
struts is very wide. Collagen struts also connect myocytes to
interstitial microvessels (thin arrow) or perimysium (thick
arrow). A, Bar520 mm; magnification 31415; B, bar510 mm,
magnification 32830.
From the Department of Pathology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
Correspondence to Professor Marcos A. Rossi, Department of Pathology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, 140049-900
Ribeirão Preto, SP, Brazil.
E-mail [email protected]
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas
Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke’s Episcopal Hospital and Texas Heart Institute, 6720
Bertner Ave, MC1-267, Houston, TX 77030.
(Circulation. 1998;97:934-935.)
© 1998 American Heart Association, Inc.
934
Rossi et al
cardium after digestion of the cellular elements. This is
expected to contribute further to the understanding of the
morphology of the connective tissue skeleton of the heart.
Acknowledgment
Professor Rossi is Senior Investigator of the Conselho Nacional de
Desenvolvimento Cientı́fico e Tecnológico (CNPq).
References
1. Weber KT, Brilla CG, Janicki JS. Myocardial fibrosis: functional significance
and regulatory factors. Cardiovasc Res. 1993;27:341-348.
935
2. Robinson TF, Factor SM, Sonnenblick EH. The heart as a suction pump.
Sci Am. 1986;254:84-91.
3. Caulfield JB, Borg TK. The collagen network of the heart. Lab Invest.
1979;40:364-372.
4. Robinson TF, Cohen-Gould L, Factor SM. Skeletal framework of mammalian heart muscle: arrangements of inter and peri-cellular connective
tissue structure. Lab Invest. 1983;49:482-498.
5. Robinson TF, Factor SM, Capasso JM, Wittenberg BA, Blumenfeld
OO, Seifter S. Morphology, composition, and function of struts between cardiac myocytes of rat and hamster. Cell Tissue Res. 1987;249:
247-255.
6. Ohtani O. Three-dimensional organization of the connective tissue fibers of
the human pancreas: a scanning electron microscopic study of NaOH treated
tissue. Arch Histol Jpn. 1987;50:557-566.
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Connective Tissue Skeleton of the Human Heart: A Demonstration by Cell-Maceration
Scanning Electron Microscope Method
Marcos A. Rossi, Monica A. Abreu and Lígia B. Santoro
Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017
Circulation. 1998;97:934-935
doi: 10.1161/01.CIR.97.9.934
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1998 American Heart Association, Inc. All rights reserved.
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