Final answer:
Two examples of a positive feedback mechanism involving oxytocin are labor contractions and milk ejection, both of which involve cycles of intensifying oxytocin release in response to the physiological demands of childbirth and nursing respectively.
Step-by-step explanation:
Two examples of a positive feedback mechanism involving oxytocin are labor contractions and milk ejection. During childbirth, the hormone oxytocin causes the uterine wall muscles to contract. As contractions increase, more oxytocin is released from the pituitary gland, which in turn causes contractions to intensify. This cycle continues until the birth of the child. Similarly, oxytocin is involved in the milk ejection reflex during nursing. As a baby suckles, oxytocin is released, causing the mammary glands to release milk, which encourages more suckling and the release of more oxytocin in a positive feedback loop.