Dense Regular Connective Tissue: Dense Connective Tissue
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Dense regular connective tissue is composed almost exclusively of tightly packed collagen (white) fibers. There may be a few elastic fibers interspersed in the ground substance. The predominant cell type is the fibroblast. Tendons and ligaments are composed of dense connective tissue. It functions to anchor muscles to bone and bone to bone. It has to be strong, not too elastic and it must withstand tensile forces. The parallel arrangement of fibers gives this tissue a lot of strength typically in one direction.
The photomicrograph to the right is an example of dense regular connective tissue. The pink fibers are thick bands of collagen. The arrows are pointing to the nuclei of fibroblasts squeezed in between the fibers.
Dense Elastic Connective Tissue: Dense Connective Tissue
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This dense connective tissue contains a large amount of elastic fibers. This allows the tissue to stretch and recoil. Dense regular connective tissue tends to be 'brittle' and dense elastic tissue tends to be more elastic. This tissue is associated with large arteries close to the heart that undergo routine expansion, ligaments of the vertebral column and with the air passageways of the lungs.
The photomicrograph to the right is a section from an elastic artery. Notice all of the dark blue staining elastic fibers.
Dense Irregular Connective Tissue: Dense Connective Tissue
This tissue is composed primarily of collagen fibers, a few elastic fibers and a few fibroblasts. The composition of dense irregular is much like dense regular; it is the arrangement of the fibers that distinguishes these two tissue types. In dense irregular connective tissue, the collagen fibers appear to be haphazardly arranged, not like the neat, parallel arrangement seen in dense regular tissue. Because the fibers extend in various directions, this tissue can withstand stress in multiple directions. This is the tissue found in joint capsules, sclera of the eye, dermis of the skin and submucosa of the digestive tract.
