Toxicological and pharmacological effects arise when chemicals interact
with biophysiological functions in discrete cell types. There is a
continuing need to screen novel compounds for their potential
therapeutic effects, and once these have been "discovered" to understand
their molecular actions, as the basis of using such compounds safely and
for rational drug design. Pharmacology now uses all of the sophisticated
molecular research techniques that are available for the development of
safer and more efficacious drugs. Histochemistry has been usefully
applied to developing new drugs (and assessing chemical safley) and is
potentially cost effective. The need to test novel substances for their
potential adverse effects has raised many questions. Toxicological
pathology has moved away from the cataloging of lesions towards
understanding the basis of the events that underly cell injury,
especially for those secondary consequences of chemical injury that lead
to malignancy and chronic disease. The focal nature of toxicologic
lesions de- mands the use of microtechniques to provide data to help
understand these questions. Histochemistry is under-utilized, but offers
one of the key ap- proaches necessary to address the problem of
understanding interactions between a cell population and a chemical, the
modulation of cellular biochem- istryor the presence of a lesion in a
test animal can be rationalised in terms of species differences that
have no relevance to man as opposed to those that are of clinical
significance or represent a warning of dire consequences to man.
