Why did Ivan Pavlov resign from the Military Medical Academy in 1924?

In 1924, the renowned physiologist Ivan Pavlov resigned from his chair at the Military Medical Academy in Leningrad as a principled protest against the institution's discriminatory policies.

The academy had begun expelling students who were the sons of priests. Pavlov, who was himself the son of a priest, stood against this injustice by declaring, "I also am the son of a priest, and if you expel the others I will go too!" His resignation serves as a testament to his character as a bold, vehement nonconformist who fearlessly defended his beliefs and stood against the unfair treatment of others, regardless of the political climate of the Soviet Union at the time.1