progesterone

n. a hormone, secreted mainly by the corpus luteum in the ovary, that stimulates the proliferation of the endometrium (lining) of the uterus required for implantation of an embryo. If implantation occurs, progesterone continues to be secreted—first by the corpus luteum and then by the placenta—maintaining the pregnant uterus and preventing further release of egg cells from the ovary. It also stimulates development of milk-secreting cells in the breasts.

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Psychology term of the day

November 18th 2024

ambiguous figure

a visual stimulus that can be interpreted in more than one way, such as an embedded figure or a reversible figure. A well-known example is the young girl–old woman image, in which the black-and-white drawing sometimes appears to be of a young girl and sometimes of an old lady. This phenomenon is not restricted to the visual: An ambiguous stimulus is one of any sensory modality that can have multiple interpretations.