Based on histology

-  Compact bone - Spongy bone

Based on maturity

-  Mature/ lamellar bone          -Immature/woven bone

Based on manner of development

-  Cartilage bone        -        Membrane bone

lamellar Bone

When we examine the structure of any bone of an adult, we find that it is made up of layers or lamellae (Fig1).

Fig 1 : How lamellae constitute bone (Schematic representation)

This kind of bone is called lamellar bone. Each lamellus is a thin plate of bone consisting of collagen fibres and mineral salts that are deposited in a gelatinous ground substance. Even the smallest piece of bone is made up of several lamellae placed over one another. Between adjoining lamellae we see small flattened spaces or lacunae. Each lacuna contains one osteocyte. Spreading out from each lacuna there are fine canals or canaliculi that communicate with those from other lacunae (Fig. 2).

Fig 2 : Relationship of osteocytes to bone lamellae (Schematic representation)

The canaliculi are occupied by delicate cytoplasmic processes of osteocytes. The lamellar appearance (Fig. 1) of bone depends mainly on the arrangement of collagen fibres. The fibres of one lamellus run parallel to each other; but those of adjoining lamellae run at varying angles to each other. T he ground substance of a lamellus is continuous with that of adjoining lamellae .

Woven Bone

In contrast to mature bone, newly formed bone does not have a lamellar structure. The collagen fibres are present in bundles that appear to run randomly in different directions, interlacing with each other. Because of the interlacing of fibre bundles this kind of bone is called woven bone. All newly formed bone is woven bone. It is later replaced by lamellar bone.