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

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

Previous surgical methods often severed these connections, which disrupted the natural regulation of the digestive process. By maintaining the vagus nerve—which plays a critical role in stimulating peristalsis and controlling digestion—Pavlov was able to observe how the stomach responded to various stimuli under conditions that closely mimicked a healthy, intact system. This precision was essential to his groundbreaking research, which ultimately earned him the Nobel Prize in 1904.132