Left Ventricular Morphology of the Giraffe Heart Examined by Stereological Methods
Article first published online: 19 FEB 2013
Copyright © 2013 Wiley Periodicals, Inc.
The Anatomical Record
Volume 296, Issue 4, pages 611–621, April 2013
How to Cite
Østergaard, K. H., Baandrup, U. T., Wang, T., Bertelsen, M. F., Andersen, J. B., Smerup, M. and Nyengaard, J. R. (2013), Left Ventricular Morphology of the Giraffe Heart Examined by Stereological Methods. Anat Rec, 296: 611–621. doi: 10.1002/ar.22672
- Issue published online: 18 MAR 2013
- Article first published online: 19 FEB 2013
- Manuscript Accepted: 7 JAN 2013
- Manuscript Received: 23 MAY 2012
- Lundbeck Foundation
- The Danish Heart Association
- Aase and Ejnar Danielsen Foundation, Villum Foundation
- The Danish Research Council and the faculties of Health Science
The giraffe heart has a relative mass similar to other mammals, but generates twice the blood pressure to overcome the gravitational challenge of perfusing the cerebral circulation. To provide insight as to how the giraffe left ventricle (LV) is structurally adapted to tackle such a high afterload, we performed a quantitative structural study of the LV myocardium in young and adult giraffe hearts. Tissue samples were collected from young and adult giraffe LV. Design-based stereology was used to obtain unbiased estimates of numbers and sizes of cardiomyocytes, nuclei and capillaries. The numerical density of myocyte nuclei was 120 × 103 mm−3 in the adult and 504 × 103 mm−3 in the young LV. The total number (N) of myocyte nuclei was 1.3 × 1011 in the adult LV and 4.9 × 1010 in the young LV. In the adult LV the volume per myocyte was 39.5 × 103 µm3 and the number of nuclei per myocyte was 4.2. The numerical density of myocytes was 24.1 × 106 cm−3 and the capillary volume fraction of the adult giraffe ventricle was 0.054. The significantly higher total number of myocyte nuclei in the adult LV, the high density of myocyte nuclei in the LV, and the number of nuclei per myocyte (which was unusually high compared to other mammalian, including human data), all suggest the presence of myocyte proliferation during growth of the animal to increase wall thickness and normalize LV wall tension as the neck lengthens and the need for higher blood pressure ensues. Anat Rec, 296:611–621, 2013. © 2013 Wiley Periodicals, Inc.