Why did Ivan Pavlov preserve the vagal nerve supply in his miniature stomach operation?

Ivan Pavlov preserved the vagal nerve supply in his miniature stomach operation to ensure that the isolated pouch remained physiologically functional, allowing him to study gastrointestinal secretions in a normal animal over its entire life span.12

By maintaining the connection to the vagus nerve—which plays a critical role in stimulating peristalsis and regulating secretions in the digestive tract—Pavlov was able to observe how the stomach responded to stimuli while isolated from ingested food. This precise surgical technique was essential for his groundbreaking research on the physiology of digestion, for which he was awarded the Nobel Prize in 1904.132