Dense Connective Tissue Proper
Dense CT is characterized by abundant collagen fibers arranged in large bundles, with a predominance of type I collagen. You’ll find relatively fewer cells and less ground substance in these specimens. Dense CT can be described further as “irregular” (DICT) or “regular” (DRCT), depending on fiber arrangement.

Dense irregular CT
Dense irregular CT consists of collagen fibers arranged in bundles that are oriented in various directions; this arrangement provides significant strength to resist stress and shearing forces in multiple directions. You will find it in the submucosa of gastrointestinal and respiratory tracts, the reticular dermis of skin, and the outer surface or “capsule” of some organs (don’t worry at this point about terminology related to specific anatomical areas – it will be described in later modules). The stroma or packaging material around secretory units and supporting epithelia also usually contain dense irregular CT.

Identify dense irregular CT in slides of adrenal gland, testis and bone

Dense regular CT
In contrast to dense irregular CT, dense regular CT consists of ordered arrays of collagen fibers (mostly type I) and very little ground substance. Specialized fibroblasts (tendinocytes) are typically seen aligned with the orientation of the fibers. The parallel arrangement and dense packing of fibers provide maximum strength for structures such as tendons, ligaments, and aponeuroses.

• Identify this tissue type in slides of tendon: longitudinal section and cross section.
• Examine the more active fibroblasts in this region, noting their characteristic features
• Note the regular parallel arrangement of the collagen fibers and relative absence of other cells besides fibroblasts
• The relatively low density of cells and blood vessels among the collagen bundles in tendon helps increase the tensile strength of this tissue but also contributes to its extremely slow rate of healing after injury.

Clinical note: Without an adequate supply of vitamin C, as in the nutritional deficiency scurvy, collagen I and II do not polymerize properly, leading to the following signs Slow wound healing Distension of blood vessels Ease of bruising Loosening of the teeth and bleeding gums Now, let’s review various types of specialized CT.