Animal Tissues - Connective Tissue Proper

Connective tissues are grouped by NCERT into loose, dense and specialised forms, and a distinctive specialised category is the fluid connective tissue. Blood is a fluid connective tissue in which formed elements, namely erythrocytes, leucocytes and platelets, remain suspended in a liquid extracellular matrix called plasma, and it circulates to transport gases, nutrients and wastes; lymph is the related fluid that drains tissue spaces. Tendon is a dense regular connective tissue made largely of collagen fibres that attaches skeletal muscle to bone, so it is solid and fibrous, not fluid. Ligament is also a dense regular connective tissue, rich in elastic fibres, that connects bone to bone, again lacking a liquid matrix. Hyaline cartilage is a specialised supportive tissue with a firm chondrin matrix, not a circulating fluid. As stated in NCERT Class 11, Chapter 7 (Structural Organisation in Animals), blood is a fluid connective tissue with a plasma matrix. A consistency check confirms that only a circulating tissue with a liquid matrix fits the description, identifying blood and lymph.