Final answer:
The amygdala is not part of Papez's circuit, which includes the mammillary body, fornix, cingulate gyrus, and hippocampus, all involved in emotions and memory.
Step-by-step explanation:
The structure that is not part of Papez's circuit is A. Amygdala. Papez's circuit is a model proposed by James Papez in 1937, which includes the Mammillary body, Fornix, Cingulate gyrus, and Hippocampus as key structures involved in the control of emotions. The amygdala, while involved in emotional processing and a part of the limbic system, is not traditionally included in Papez's circuit. The correct structures forming Papez's circuit are related to emotional expression and memory formation.