Connective Tissue Proper:

Adipose tissue is fat cells it has many cells together, so in a sense it is a connective tissue, but it can also occur by itself
Adipocyte is a fat cell, also called “Reticulocyte”
There are white fats and brown fats

Two main types of connective tissue:
loose and dense.

We will be discussing:
Fixed cells and Wandering cells

Fixed cells:
Fibroblast- fusoform cells with elongated nuclei. Totipotent. Responsible for producing collagen
Adipocytes- Are large cells that Just want to be filled with lipids
Nucleus is all the way out to the cell membrane, pushed against the cell wall
You can see how much fat you are taking on based on the size of this cell

Wandering cells:
Cells that go in and out of the the connective tissue.

Macrophage- "trash collector" - Helps keep connective tissue clean.
Lymphocytes - little is known about function
Plasma cells- have a “clockface” heterochromatin.
Mast cell- involved in immune response and histamine release.
Eosinophils- stain bright red - little is known about function
Monocytes

Types of fibers:
Collagen- most common.
Colorless strands.
.5 microns.
Eosinophilic in H&E stains.
Unbranched, solid strands.
Randomly oriented in LCT.
In living condition is birefringent.
There are parallel microfibers running down the length of the collagen.
16 different types.
Elastic fibers- very thin
elongate fibers, high in elasticity.
4-5 microns in diameter.
Very difficult to see if not stained.
Stained with orcein.
“argyophilic”, which means “silver-loving”.
much thinner and more elastic than collagen
Wavy end, that looks like a split end.
Fibrillin coat around them with elastin core.
Found in Loose Connective Tissue.
Found in the lining of blood vessels, fused together into thicker sections.
Reticular fibers- about the same diameter of elastic fibers.
Not in a long strip, but found in a network, with little extensions.
Coated with reticulin.
Type of collagen found in the spleen, lymph nodes.
Found in spongy organs mostly.
Argyophilic.
Completely surrounds and supports cells.
Found in Loose Connective Tissue.

Loose Connective Tissue:
Widespread.
Found throughout the body.
Occupies spaces around muscles.
Seen best in villi in the intestinal tract.
A lot less fibers, very loosely arranged, not fused together.
Lamina propria is the specific name for the Loose Connective Tissue within the core of the villi in the intestine.
In umbilical cord, specifically called “wharton’s jelly”.

Dense connective tissue:
Differs from loose connective tissue in that there are more fibers, but relatively few cells.
Found in two forms:
irregular and regular.

Dense irregular:
Fibers are very parabolic.
Best place to look is in the dermis of the skin.
You can see the nuclei and fibroblasts that are producing collagen.

Dense regular:
Fibers oriented in a parallel fashion, very close to one another.
Found in tendons and ligaments, places where you need strength.