HISTOLOGY - SPECIAL JUNCTIONS

• Three special types of connective tissue are cartilage, bones, and blood
• Cartilage and bones are under special types of dense regular connective tissue
• Blood is under loose connective tissue
• Cartilage and bone can also be referred to as organs because they are made up of tissues, associated with blood vessels, and are lines with connective tissue
• Main cells of cartilages are chondrocytes
• Main cells of bones are osteocytes
• Cartilage is also known as gristle
• Hyaline cartilage is the most abundant type of cartilage
• Hyaline cartilage forms the majority of the skeleton of the fetus
• Hyaline cartilage define as glistening, smooth, pearly white appearance in fresh tissues
• Chondrocytes and Osteocytes are group of cells inside the lacunae
• Daughter cells of chondrocytes are called isogenous cells
• Cartilage matrix consists of an amorphous ground substance and extracellular fibers
• Ground substance are made up of proteoglycans same as connective tissue proper
• The ground substance is blue in h&e staining
• Extracellualar fibers are mostly made up of collagen type ii fibers
• Elastic cartilage is yellowish in fresh tissue
• Elastic cartilage is found in the external meatus of the ears, auditory tubes, epiglottis, some parts of the larynx
• Fibrous cartilage can withstand greater stress than hyaline and elastic cartilage
• Fibrous cartilage appears white in fresh specimens
• Perichondrium is a special type of dense irregular connective tissue
• Chondrogenic layer has cells called osteoprogenitor cells and chondroblasts
• Chondrogenic potency refers to the ability to form cartilage
• Perichondrium consists of a fibrous layer and a chondrogenic layer that adheres to the cartilage
• Chondroblasts SYNTHESIZE THE CONSTITUENTS OF CARTILAGE MATRIX AND THE PRECURSORS OF EXTRACELLULAR FIBERS.
• CHONDROBLASTS ACQUIRE LACUNAE AND TRANSFORM INTO CHONDROCYTES
• Long bones confined to the extremities
• Long bones has so call body or shaft which is hollow
• Long bones has 2 ends namely the proximal and distal epiphyses which are covered by articular cartilage
• Short bones are cuboidal, seen in the wrist and ankle
• Flat bones can be seen at sternum, bones of the skull, scapulae
• Irregular bone are found in the vertebrae, hip bones, bones of the skull that are not flat
• Sesamoid bones are bones that develop in tendons that rub bony surfaces and can be found in patella or knee cap
• Two forms of bone tissue are compact and spongy
• Compact bones appears solid
• Spongy bones has numerous cavities or spaces
• Bones have an inner region that is made up of spongy bone
• Long bones contain paranasal sinuses or medullary cavities
• Periosteum is the external surface of the bone
• Endosteum is the internal surface of the bone