Epithelial Tissue Characteristics:

Simple Squamous Epithelial Description: Single layer of flat cells. Location: lining of lungs and heart, blood vessels, ventral cavity and at kidney glomeruli. Function: allows passage of materials by diffusion where protection isn’t as important; also aids in secretion

Stratified Squamous Epithelial These keratinized epithelial cells will Be sloughed off. Description: multiple layers of flat cells (basal layer is usually columnar or cuboidal). Location: skin, lining of the cheek. Function: creates a barrier that protects body from abrasion Apical Layer Basal Layer

Simple Cuboidal Description: Single layer of cube-shaped cells. Location: small ducts of glands, kidney tubules, surface of ovary. Function: secretion & absorption Cell is as wide as it is high. One central nucleus

Simple Cuboidal Cells closely packed together and touching one another Lumen: Inside space of Tubular structure Cells closely packed together and touching one another Has a basal surface and apical surface Avascular Sits on a basement membrane (can difficult to see on slide) Apical Surface Nucleus Basal Surface

Non- Ciliated Simple Columnar Description: Single layer of non-ciliated rectangular cells; contain goblet cells and sometimes microvilli. Location: GI tract, ducts, gallbladder Function: secretion and absorption

Nuclei lie near base of cell Goblets secrete mucous at apical surface to lubricate lining of GI, respiratory, reproductive and urinary systems. Microvilli increase surface area for absorption. Simple Columnar Cells Goblet Cell Nucleus Goblet Cell

Pseudostratified Ciliated Columnar Epithelium Description: Appears stratified because nuclei are at varying levels. Location: Ciliated lines airways of upper respiratory tract (trachea). Function: Mucus from Goblets traps foreign particles and are swept away by cilia. Goblet Cells

Goblet Cells secreting mucus Cilia Nuclei at varying levels

Epithelial and Connective 1 1 – pseudostratified columnar epithelial 2- simple cuboidal epithelial 3- hyaline cartilage connective tissue 2 3

Loose Areolar Connective Tissue Description: gel-like matrix with elastic & collagen fibers. Location: lies underneath epithelia, wraps capillaries, and can package organs Function: wraps and cushions organs; plays important role in inflammation and immune response

Loose Areolar Connective Tissue Fibroblast CELLS MATRIX FIBER Elastic Fiber Collagen Fiber (thicker pink ones) Loose Areolar Connective Tissue GROUND SUBSTANCE

Dense Regular Connective Tissue Description: Mostly collagen fibers with fibroblasts between rows. Matrix looks white and shiny. Location: Tendons, ligaments and aponeuroses. Function: Strong attachment!

Dense Regular CT (magnified) Fibroblasts Fibers are mostly Collagen.

Reticular Connective Tissue Reticular Cells Description: Network of interlacing reticular fibers & reticular cells Location: Found in liver, spleen, lymph nodes, & red bone marrow. Function: Acts as a filter in spleen and lymph nodes. Blue staining Reticular fibers

Reticular Connective Tissue Remember that connective tissue is vascular. (Avascular epithelial tissue depends on diffusion of nutrients and waste through blood vessels in CT). Blood vessel: Single layer of Epithelial cells forms vessel tube.

Reticular CT 1 2 1- Reticular cells 2- Blood vessel 3 2 1- Reticular cells 2- Blood vessel 3- Reticular fibers