It is the most numerous and important cell in loose connective tissue and can synthesize proteins.

When the function is active, the cell body is larger and has many processes; the nucleus is large, oval, lightly colored, and the nucleolus is obvious; the cytoplasm is rich and weakly basophilic.

Rich in rough endoplasmic reticulum and well-developed Golgi complex

The synthesized protein is continuously secreted out of the cell through exocytosis, so there are no obvious secretory granules in the cytoplasm.

Fibroblasts synthesize and secrete collagen and elastin, and form an amorphous matrix

Synthesize secreted proteoglycans, etc., to form the matrix

Synthesize biologically active substances and participate in various processes

Continuous secretion of protein - no storage - no obvious particles

Fibroblasts (reserve army of fibroblasts)

A type of immune cell widely present in the body, derived from monocytes in the blood

Various forms, changing with functional status

The nucleus is small, round or kidney-shaped, deeply colored, and the cytoplasm is rich, mostly eosinophilic, and may contain phagosomes, foreign particles, and vacuoles.

There are many wrinkles, microvilli and a few spherical ridges on the cell surface

The cytoplasm contains a large number of lysosomes, phagosomes, phagophore vacuoles and residual bodies

There are more microfilaments and microtubules inside the cells and pseudopodia

When macrophages in a resting state are stimulated by bacterial products, inflammatory denatured proteins and other substances, the cells extend pseudopods and move along the concentration gradient of these chemicals toward high-concentration sites, where they gather to produce and release these chemicals. parts of the body and are therefore called migrating activated cells. This characteristic of cells is called chemotaxis, and these chemicals are called chemokines. Chemotaxis is the prerequisite for macrophages to function.

Phagocytosis

Antigen presentation

Secretion function: can synthesize and secrete hundreds of biologically active substances

Mainly distributed in the connective tissue or lymphoid tissue of the spleen, lymph nodes, digestive tract, respiratory tract and other mucous membranes, as well as in chronic inflammation sites

The cells are larger, round or oval; the nucleus is small, round, and centered; the cytoplasm is filled with thick basophilic secretory granules, which can be stained purple by aldehyde-fuchsin.

It is often distributed along small blood vessels and lymphatic vessels, and is more common in the dermis of the skin, mucous membranes of the respiratory tract and digestive tract.

secretory granules

Exist singly or in groups

Cell body is large, often spherical or polygonal

The cytoplasm contains a large lipid droplet

In HE-stained specimens, lipid droplets are dissolved and cells appear vacuolated.

Can synthesize and store fat and participate in lipid metabolism

are stem cells

It is mostly distributed around small blood vessels and looks like fibroblasts.

Can differentiate into fibroblasts, vascular endothelial cells, smooth muscle cells, etc., and participate in the repair of connective tissue and small blood vessels

Exercising immune defense function

The biggest amount

Collagen fibers in HE-stained sections were eosinophilic, varied in thickness, wavy, branched, and intertwined into a network.

Collagen fibers are often found in bundles

High toughness and strong tensile strength

Contains less collagen fibers, but is widely distributed

In HE-stained sections, elastic fibers are light red (aldehyde-fuchsin staining stains elastic fibers purple) and are difficult to distinguish from collagen fibers.

Elastic fibers are thin, with a smooth surface. The ends are often curled, may have branches, and are interwoven into a network.

Made of elastin, microfibrils

It is elastic, making loose connective tissue both elastic and tough, which helps the organs and tissues to maintain a relatively constant shape and position while also having a certain degree of variability.

Many branches, intertwined into a network

Mainly composed of type III collagen, the surface is coated with glycoprotein, and appears light red like collagen fibers in HE stained sections.

Because they appear black in silver-stained sections, they are also called argyrophilic fibers.

Mainly found in reticular tissue, also distributed in the reticular plate of basement membrane, acini, around capillaries, etc.

Aminoglycan

protein

A large number of proteoglycan aggregates form a molecular sieve with many micropores, allowing water, nutrients, metabolites, hormone gas molecules, etc. to pass through Macromolecular substances and bacteria that are larger than the pores are blocked, making the matrix a defensive barrier that limits the spread of bacteria and other harmful substances. Hemolytic streptococci and cancer cells can spread or metastasize because they can produce hyaluronidase and destroy the matrix structure.

The molecular surface has binding sites for a variety of cells, collagen and proteoglycans, so it is a medium for organically connecting these three components.

In the capillary arterial segment, an aqueous solution containing small molecules such as electrolytes, simple sugars, and gas molecules dissolved passes through the capillary wall and penetrates into the matrix to become tissue fluid.

Make up the body fluid environment that cells need to survive