The article discusses the inhumanity of alcohol and other experiments on pregnant mice in biological education. Use of "indicator" animals with known microbiological status. Animals are placed in the same environment as the population being tested and periodically sacrificed and examined. Naked (athymic) mice are excellent indicators because they are immunodeficient and especially susceptible to pathogens. But these mice are not suitable for detecting changes in serological titer, which may indicate the presence of viruses, since there is no antigenic response in nude mice. To determine the serological titer, it is necessary to use animals with the appropriate immune status.