Table 2.06 - Some Human Heart Facts from a Cellular Point of View:

DNA:

Concentration highest at birth, decreases with growth.

At birth - 1/2 in muscle cells, 1/2 in fibroendothelial cell nuclei.

By childhood - 2/5 in muscle cells, 3/5 in fibroendothelial cell nuclei

Adult - less than 1/3 in myocytes, 2/3 in fibroendothelial cell nuclei

Cell Numbers:

Myocyte nuclei double in LV after birth; also in RV but occurs a little later.

Myocyte numbers in human heart 2,000,000,000; at birth 7-9000,000,000, and in childhood 1- 2,000,000,000.

There are an equal number of fibroblasts at birth, later 4-6,000,000,000.

Capillary Density:

4,000 per mm² in infants, 3,342 per mm² in adults

Faster proliferation of capillaries relative to myocytes occurs during postnatal development

Mean intercapillary distance decreases from 31-18 um.