The connective tissues have mesodermal origin.
They are morphologically characterized by having several types of cells immersed in a large amount of extracellular material, amorphous substance or matrix, which is synthesized by the tissue cells themselves.
The matrix is an amorphous, gelatinous and transparent looking mass. It consists mainly of water and glycoproteins and a fibrous part of protein nature, the connective fibers.
The connective cells are of various types. The main ones are presented below.
Metabolically active cell, containing long and thin cytoplasmic extensions. Synthesizes collagen and matrix substances (intercellular substance).
Egg cell, which may contain long cytoplasmic extensions and numerous lysosomes. Responsible for phagocytosis and pinocytosis of particles foreign or not to the organism. Removes cellular debris and promotes the first fight against invading microorganisms of our organism. Active in the process of physiological involution of some organs or structure. This is the case of the uterus that, after delivery, suffers a reduction in volume.
Large globular cell, without prolongation and full of granules that make it difficult to see the nucleus. The granules are comprised of heparin (anticoagulant substance) and histamine (substance involved in allergy processes). This last substance is released in times of penetration of certain antigens in the body and their contact with mast cells, triggering the consequent allergic reaction.
Ovoid cell, rich in rough endoplasmic reticulum (or granular). Little in the normal range, but abundant in places subject to the penetration of bacteria, such as the intestines, skin and places where there are chronic infections. Producer of all antibodies in the fight against microorganisms. It originates in connective tissue from the differentiation of cells known as B lymphocytes.
The different types of connective tissue are widely distributed throughout the body, and may perform space-filling functions between organs, support function, defense function and nutrition function.
The classification of these tissues is based on the composition of their cells and the relative proportion between extracellular matrix elements. The main types of connective tissues are: loose, dense, adipose, reticular or hematopoietic, cartilaginous and bony.