Post on 29-Jan-2016
CONNECTIVE TISSUE
Origin of connective tissue cells
LOOSE CONNECTIVE TISSUE
• Characterized by loosely arranged fibers and an abundance of cells
• The primary location is :• beneath those epithelia that cover the body
surfaces and line the internal surfaces of the body
• In association with the epithelium of glands• surrounds the small vessels
Loose connective tissue (scheme)
Light micrograph of loose C.T.
Connective tissue cells can be categorized as fixed and wandering
Fixed cell population Wandering cell population
- Fibroblasts - Lymphocytes- Myofibroblasts - Plasma cells- Macrophages - Neutrophils- Mast cells - Eosinophils- Adipose cells - Basophils- Reticular cells - Monocytes- Undifferentiated stem cells
E.M. of fibroblast portion with the adjusting collagen fibers
E.M. of a macrophage surrounded with collagen fibers
L.M. of macrophages in liver (von Kupffer cells)
Specific names of different location macrophages (macrophage
system)• Monocytes (blood)• Macrophages-histiocytes (connective tissue)• Dust cells (lung alveoli)• Kupffer cells (liver)• Langerhans cells (skin)• Hofbauer cells (placenta)• Osteoclasts (bone)• Microglia (brain)• Dendritic cells (lymphoid organs)• Microfold (M) cells (intestine)
E.M. of a mast cell
Physiologically active substances secreted by mast cells
E.M. of adipocytes on different stages of maturation
Plasma cell schematic representation
NON-CELLULAR COMPONENTS OF CONNECTIVE TISSUE
Fibers• Collagen fibers – forms the most abundant fibers of
connective tissue • Reticular fibers – provide a supporting framework for
the cellular constituents of lymphoid organs mostly• Elastic fibers – provide tissues with the ability to
respond to stretch and distension
Ground substance – consists largely of highly hydrated proteoglycans, of hyaluronic acid, and GAG (chodroitin-sulphate, heparan-sulphate, dermatan-sulphate, keratan-sulphate)
CLASSIFICATION OF CONNECTIVE TISSUES
DENSE CONNECTIVE TISSUE
• DENSE IRREGULAR CONNECTIVE TISSUE is characterized by an abundance of fibers and few cells. It forms the reticular or deep layer of the dermis
• DENSE REGULAR CONNECTIVE TISSUE is characterized by ordered and densely packed arrays of fibers and cells. It is the main functional component of tendons, ligaments, aponevroses
L.M. of a tendon, cross section