4. Specialised Connective Tissues
These include Cartilage, Bone and Blood; and since cartilage precedes
bone in development, the process of Ossification will be outlined
(Lecture 4).
All three of the specialised CTs differ from CT Proper in that they have a
greater proportion of extracellular matrix; in cartilage and bone the
matrix is solid.
4.1 Cartilage
Develops from mesenchyme. Provides good support while retaining
flexibility. Uniquely among connective tissues, it lacks blood vessels and
nerves. There are three types of cartilage.
a) Hyaline Cartilage. The commonest type of cartilage. Cartilage cells
(chondrocytes) occupy spaces (lacunae; singular, lacuna) in the matrix
which is slightly basophilic due to high content of glycoproteins. The
chondrocytes shrink in preparation and are vacuolated (due to the
presence of unstained glycogen and lipid). Collagen fibres form a fine
feltwork but are not visible with normal staining methods.
Locations — larynx, trachea, bronchi, articular surfaces of joints.
b) Elastic Cartilage contains a large proportion of elastic fibres (demonstrable
by special staining methods) for greater flexibility.
Location — external ear.
c) Fibrocartilage. (See above, Section 3.2c)
Location — tendinous insertions; vertebral disc.