Simple Squamous

Appear flat, single layer of cells, sparse cytoplasm, diffusion easy, protection not critical, found in lung air sacs, blood vessels, kidney glomeruli, etc. 

Looks like floor tiles or fried eggs!

Simple Cuboidal

Appear tall as wide, single layer of cube-like cells, round & central nuclei stain dark, found in kidneys and glands where absorption and secretion are important

Simple Columnar

Single layer of tall cells, round to oval nuclei in “stripes”, some cells have cilia, may have goblet cells that secrete mucus, function in absorption, secrete mucus if cilia present (lungs), non-ciliated found in GI. 

Pseudo-Stratified Columnar

Cells vary in height, ALL cells rest on basement membrane, only tallest cells reach free surface, nuclei at different levels, NOT many layers of cells – only 1 layer (pseudo prefix).

Secretes or absorbs substances, cilia sweeps mucus that line the respiratory tract and moves dust AWAY from the lungs.

Stratified Squamous

Many cell layers, high abrasive “dry” areas like skin  (keratinized) or moist linings of esophagus (non-keratinized). 

Basal layers cuboidal or columnar and reproducing. Surface cells are “dead” and appear flat (squamous shape). Basal cells are actively mitotic, producing new cells that get pushed upward into the overlying layers. As these cells are pushed up, they become flatter and longer (just as if you were to squash something), taking on the typical squamous shape.

When the cells reach the top, they are sloughed off and replaced by cells from below.

Transitional

Forms lining of urinary bladder, which stretches as it fills. Cells at basal layer are cuboidal or columnar, and apical cells vary in shape depending on stretch.

When urinary bladder is distended with urine, domelike apical cells flatten and look squamous to permit a greater volume of urine to be stored. 

Stratified Cuboidal

A rare tissue found in mammary, salivary and sweat glands, often has 2 layers of cuboidal cells.

Adipose

Consists of ADIPOCYTES (large amount of lipids).

•White fat stores nutrients and makes ATP.

•Brown fat has many mitochondria that heat blood. Specialized around neck, kidneys &

  axillae. Babies have only brown fat and cannot yet shiver to make heat.

•Consists of LARGE CELLS (fat is 90% of cell) & LITTLE MATRIX.

•Serves to INSULATE, PROTECT & STORE ENERGY, especially in subcutaneous areas.

Dense Regular

• Has protein fibers in ECM that are oriented in 1 direction

• Has collagen fibers (white appearance)

• Form structures such as tendons and ligaments

• Resist stretching

Dense Irregular

Protein fibers are mesh-like and are Randomly Oriented.

Direction of the fibers is at Right Angles.

Sheets of connective tissue have Strength In All Directions instead of just one (like

  dense/regular).

Examples are the Dermis, surrounding organs, and walls of arteries.

Reticular

Network of fibers in a loose ground substance, supports white blood cells, mast cells, macrophages, found in lymph nodes, bone marrow, spleen.

Elastic

Has many elastic fibers (has the ability to return to original shape) and a few collagen fibers (strong and flexible, but inelastic). Found in arteries (like aorta of heart), vertebral ligaments, or walls of bronchial tubes. 

   TRACHEA & BRONCHI, TIP OF NOSE,

     intervertebral discs, pubic symphysis, knee, jaw

Resembles paint brush strokes!