Neurotropic attraction: facts and fiction

Traumatic lesions to the spinal cord of adult individuals will cause degeneration of the severed distal axons, retraction of the severed proximal axons, scar formation in the damaged area, and eventually regenerative signs, which will occur along the retracted proximal axons. Growth cone-like appendages appear and regenerating axons enter the scar tissue. Within the relatively unstructured scar tissue the growth cones appear to lose their sense of direction, as well as their motive force, and progress ceases. The regenerative effort does not result in the establishment of any connection.Biomedical Reviews 1995; 4: 95-102

Chemically defined culture media: rational recipes or witches' brew?

A rational approach to study cells, tissues or even organs is to isolate them from the body and bring them into a controlled, and therefore reproducible, environment. In vivo, cells are surrounded by the extracellular matrix, and the body fluids nourish them. In vitro, these fluids are replaced by culture media. In the early days of tissue culture, tissue was cultured in a drop of clotted lymph. The early-day natural nutrient media have gradually become replaced by media of a more defined composition, culminating in the advent of completely defined culture media.Biomedical Reviews 1996; 6: 111-119