GENERAL HISTOLOGY

Detailed explanation-1: -This immature bone is later replaced by secondary or lamellar bone (mature). Secondary bone is further classified as two types: trabecular bone (also called cancellous or spongy bone) and compact bone (also called dense or cortical bone).

Detailed explanation-2: -Mature lamellar bone exists as cortical (also called compact) or trabecular (cancellous, spongy) bone.

Detailed explanation-3: -A lamellar unit is composed of five sublayers. Each sublayer is an array of aligned mineralized collagen fibrils. The orientations of these arrays differ in each sublayer with respect to both collagen fibril axes and crystal layers, such that a complex rotated plywood-like structure is formed.

Detailed explanation-4: -Lamellar bone makes up the compact or cortical bone in the skeleton, such as the long bones of the legs and arms.