Hematoxylin & Eosin

Different types of connective tissue stained with hematoxylin & eosin (H&E). H&E stains collagen (pink/red) and muscle (pink).

• Adipose Tissue - a specialized, loose connective tissue that contains large numbers of adipocytes. The cells are empty because lipids are extracted during specimen preparation. It also contains small amounts of collagen fibers stained pink/red.
• Loose Connective Tissue - mesentery is an example of loose connective tissue. Mesentery is folds of connective tissue that attach organs to the walls of the abdomen. It is composed of collagen fibers interspersed with adipocytes, blood vessels and nerves.
• Dense Connective Tissue - fascia lata is an example of dense connective tissue. The fascia lata is connective tissue that encloses thigh muscles. Collagen fibers are located to the left and muscle fibers to the right and both are stained pink/red. (Azan can be used to distinguish collagen from muscle fibers.)
• Elastic Connective Tissue - the ligamentum nuchae is an example of elastic connective tissue. The ligamentum nuchae is a ligament at the back of the neck. Dense regular connective tissue with both collagen and elastic fibers. These are difficult to distinguish from each other with H&E. (Verhoeff stain can be used to identify elastic fibers.)
• Embryonic Connective Tissue - the umbilical cord is an example of embryonic connective tissue. The umbilical cord connects the developing fetus and the placenta. The bluish-pink color is from ground substance (blue) and sparse collagen fibers (pink). The collagen and muscle of blood vessels is stained pink. (Azan can be used to distinguish collagen from muscle fibers.)

Azan

Different types of connective tissues stained with azan. Azan stains collagen (blue) and muscle (red).

• Adipose Tissue - a specialized, loose connective tissue that contains large numbers of adipocytes. The cells are empty because lipids are extracted during specimen preparation. IT also contains small amounts of collagen fibers stained blue.
• Loose Connective Tissue - mesentery is an example of loose connective tissue. Mesentery is folds of connective tissue that attach organs to the walls of the abdomen. It is composed of collagen fibers interspersed with adipocytes, blood vessels and nerves.
• Dense Connective Tissue - fascia lata is an example of dense connective tissue. The fascia lata is connective tissue that encloses thigh muscles. Collagen fibers are located to the left are stained blue and muscle fibers to the right are stained red.
• Elastic Connective Tissue - the ligamentum nuchae is an example of elastic connective tissue. The ligamentum nuchae is a ligament at the back of the neck. It is dense regular connective tissue with both collagen and elastic fibers. The collagen fibers are stained blue and the elastic fibers appear red in this specimen. (Verhoeff stain can be used to distinguish elastic fibers.)
• Embryonic Connective Tissue - the umbilical cord is an example of embryonic connective tissue. The umbilical cord connects the developing fetus and the placenta. The bluish color is from the sparse collagen fibers. The muscle of the blood vessels is stained red.

Verhoeff Stain

Different types of connective tissue stained with Verhoeff stain. It intensely stains elastic fibers (black) and lightly stains collagen (red).

Elastic connective tissue is the only specimen that contains significant amounts of elastic fibers.

• Elastic Connective Tissue - the ligamentum nuchae is an example of elastic connective tissue. The ligamentum nuchae is a ligament at the back of the neck. It is dense regular connective tissue with both collagen and elastic fibers. The abundant, compact masses of elastic fibers are intensely stained black.