Primary cell cultures

The cell types used in cell culture fall into two categories generally referred to as either a primary cultured or a cell line.

Primary cell cultures
Primary cultures are cells derived directly from tissues following enzymatic dissociation or from tissue fragments referred to as explain. These are usually the cells of preference, since it is argued that primary cultures retain their characteristics and reflect the true activity of the cell type in vivo. The disadvantage in using primary culture, is that isolation can be labor intensive and may produce a heterogeneous population of cells. Moreover primary cultures have a relatively limited life span and can be used over only a limited period of time in culture.
Primary cultures can be obtained from many different tissues and the source from the endothelium of blood vessels are referred to as endothelial cells whilst those isolated from teh medial layer of the blood vessels and other similar tissues are smooth muscle cells. Although both can be obtained from the same vessels, endothelial cells are different in morphology and function, generally growing as a single monolayer characterised by a cobble-stoned morphology. Smooth muscle cells on the other hand are elongated, with spindle-like projections at either end and grow in layers even when maintained in culture. In addition to these cell types there are several other widely used primary cultures derived from a diverse range of tissues, including fibroblasts from connective tissue, lymphocytes from blood, neurones from nervous tissues and hepatocytes from liver tissue.