Dense irregular CT: This type of CT varies in the density and arrangement of collagen fibers,

• Ranging from a very sparse amount of collagen (loose or areolar CT) to
• Heavy, wavy masses of collagen (dense irregular CT).
• The stroma or packaging material around secretory units or other functional components in organs usually much collagen and is referred to as dense irregular CT.

Examine slide 45, most of which is CT, and notice the gradations in the amount of pink-staining collagen in different regions. Examine the CT in dermis of the skin in slides 36, 51, 89 and 5, which have different stains, noting again the different densities of CT.

Clinical note: Following injury to any tissue or organ, connective tissue proper is the usual site of the inflammatory response, a process that involves all the cells of the tissue. The events of wound healing mainly involve cells and fibers of the connective tissue and the formation of scars involves excessive or otherwise abnormal production of new fibroblasts and collagen during this process.

What is the difference in collagen staining in the two common stains?

Examine the ultrastructural appearance of fibroblasts and collagen fibers in Fig. 5-8.

What are the distinguishing characteristics of fibroblasts actively making collagen?.

Dense regular connective tissue.