Lactation (or the production of mother’s milk) is caused by changes in estradiol levels after birth and the suckling of the newborn. The hypothalamus signals the anterior pituitary glands, which result in the production of milk in the mammary glands. The milk is released from the mammary glands when the suckling stimulates the secretion of oxytocin from the posterior pituitary gland.
As the seed of a fruit develops in its fertilization process, the ovary walls thicken in order to protect it more effectively. Fruits protect dormant seeds and aid in their dispersal. Some fruits are fleshy (tomatoes, plums, grapes) while others are dry (cereal grains).