The manner by wchich the osteocytes are organized in the bone results into two types of bone tissue.
a) Non-lamellar bone, also called primary, or immature bone;
b) Lamellar bone, also known as secondary, or mature bone.
The immature bone is always the first to form in the body, such as during fetal life, during bone growth, bone remodeling, healing of bone fractures. In adults, it exists only in few places in the body, one example being the dental alveoli that hold the teeth.
The mature bone normally replaces the immature bone and is the predominant type in adults.
Main differences between these types:
Immature or non-lamellar bone: the collagen fibers of the extracellular matrix are arranged in many directions, and the osteocytes are not regularly arranged lacking a specific organization. It contains more cells per volume than the lamellar bone.
Mature or lamellar bone: the collagen fibers are organized in sheets called bone lamellae. Within each sheet, the collagen fibers are arranged parallel to each other. In adjacent lamellae the direction of its collagen fibers maintain an angle in relation to the collagen fibers of their neighboring lamellae. The osteocytes have an organized distribution, betveen the lamellae.
More information on lamellar and non-lamellar bone will be presented in the following pages.
