ABSTRACT

Bone is composed of mineral and mineral ions, water and an organic matrix. Although the relative proportions of mineral, water, and matrix molecules of bone vary among types, species, and development ages of bone, the overall chemical composition of bone is amazingly constant (Table 1). Most of the macromolecules and mineral in bone occur extracellularly. It is the interaction of the cells with the extracellular matrix, as well as the interactions of all of the extracellular matrix components, which enable bone to perform its unique functions, providing mechanical strength and maintaining calcium and phosphorus homeostasis. The Composition of Various Bones Calculated from Published Data

Source

Age

Type

%H2O

Percent of dry wt

Mineral

Collagen

GAG

Lipid

Cow

calf

periosteal

*

54.0 a

22.2 a

0.38 a

*

cancellous

*

52.0 a

19.4 a

0.52 a

1.7 b

cortical

*

63.0 b

16.9 b

*

0.6 b

adult

cortical

9.1 c

76.4 c

21.5 c

0.20 c

1.03 c

Human

fetal

cortical

*

70.8 d

18.3 d

0.53 d

*

2—13 yr

cortical

*

73.7 d

17.7 d

0.4l d

*

adult

cortical

7.3 e

67.2 e

21.2 e

0.34 d

1.6 f

membranous

15.2 e

67.4 e

21.1 e

0.28 e

*

Rat

weanling

cortical

*

68.4 f

19.0 f

0.5 f

1.2 f

cancellous

*

54.5 f

21.0 f

0.4 f

2.8 f

adult

cortical

12.0 f

69.0 g

20.0 g

0.61 f

2.5 g

cancellous

*

54.0 g

15.7 g

0.69 f

3.2 g

Glycosaminoglycan.

Not determined.

Reference 57.

Reference 52.

Reference 58.

Reference 59.

Reference 60.

Unpublished data.

Reference 53.