and physiologic fluid flow conditions taking place inside the body. Multi-compartmental perfused systems New testing platforms are now developed to solve problems related to cellular interactions. These new platforms are much more complex based on multi-compartmental perfused systems. The main objective of these systems is to reproduce in vivo mechanisms more reliably by providing cell culture environment close to the in vivo situation. Each compartment in the system represent a specific organ of the living organism and thus each compartment has a specific characteristics and criteria. Each compartment in these systems are connected by tubes and pumps through which the fluid flows thus mimicking the blood flow in the in vivo situation. The draw back behind the use of these perfused systems is that, the adverse effects ( influence of both the biological and non-biological components of the system on the fate of the chemical under study) are more compared to the static systems. In order to reduce the effect of non-biological components of the system, all the compartments are made of glass and the connecting tubes are made up of teflon. A number of kinetic models have been proposed to take care of these non-specific bindings taking place in these in vitro systems. To improve the biological difficulties arising from the use of different culture in vitro conditions, the traditional models used in flasks or micro-well plates has to be modified. With parallel development in micro-technologies and tissue engineering, these problems are solved using new pertinent tools called "micro-fluidic biochips". References Toxicology Alternatives to animal testing