Ch. 6— Alternatives to Animal Use in Research • 139 
example, can be used to perform analyses inside 
ducts and blood vessels with little discomfort and 
no permanent damage to the animal. Continued 
developments in analytical instrumentation, in- 
cluding noninvasive imaging techniques such as 
magnetic resonance imaging, will likely ameliorate 
the degree of experimental insult faced by research 
animals. 
In vitro technology has affected virtually every 
field of biomedical research. This technology en- 
tails the maintenance of organs, tissues, and cells 
outside of the body and may affect research ani- 
mal use in two important ways. First, when or- 
gans, tissues, or cells are removed from animals 
and cultured, experiments may be conducted with 
fewer animals than would be necessary in whole- 
animal experiments and, of course, without pain. 
Cells from one animal, for example, may be divided 
among a dozen experimental cultures and a dozen 
control cultures, replacing 24 animals that might 
be used in a comparable whole -animal experiment. 
Second, when cells proliferate in culture, com- 
mercially available cell lines can completely elimi- 
nate animal use in some experiments. Such cell 
cultures are derived directly from preexisting cell 
cultures— not animals . Researchers have used, for 
example, a monkey kidney cell line to study the 
metabolic effects of general anesthetics. 
In vitro experiments are not equivalent to whole - 
animal experiments. In in-vitro systems, as orga- 
nization is disrupted or lost, the in vitro system 
has less and less of the kind of interactions that 
characterize cells in the body . This can be an advan- 
tage and a disadvantage. Interactions may cause 
extraneous phenomena that obscure the process 
under study. Conversely, the absence of interac- 
tions may produce results that are at variance with 
what actually occurs in the live animal. Conclu- 
sions drawn from in vitro studies must eventually 
be validated by comparison with results of whole- 
animal experiments. 
In some areas of biomedical research, inver- 
tebrates and micro-organisms can be used, and 
even plant parts can yield information about ani- 
mal systems. Structures within plant and animal 
cells, when removed from the cells, are essentially 
indistinguishable in both appearance and function. 
Cell biologists, for example, use yeast cells as a 
source of mitochondria— the energy -generating 
structures present in all plant and animal cells. 
Hard and fast distinctions between biomedical 
and behavioral research are difficult to sustain. 
Nevertheless, it is apparent that there is even less 
potential for replacement of animals in behavioral 
than in biomedical research. In vitro techniques 
and nonliving systems are not viable alternatives 
to the use of animals in behavioral research. 
Invertebrates are used extensively in behavioral 
research. Octopuses and squid are studied because 
of their highly developed brains. In addition, the 
discovery of learning and memory in single-cell 
organisms has challenged the widely held assump- 
tion that these phenomena are properties of the 
interactions of nerve cells rather than of individ- 
ual cells, and has opened new avenues of research 
with nonanimal methods. 
Computer simulation is a valuable tool in bio- 
medical and behavioral research, but it does not 
stand as a replacement for animal use. The devel- 
opment of new and more sophisticated computer 
simulations in biomedical and behavioral research 
is predicated on data derived from animals. In- 
creased use of computer simulation may have the 
paradoxical effect of leading to an increase in the 
number of animals used in experimentation, as 
more hypotheses and experimental questions are 
generated more rapidly. 
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