different maturation time of androecium and gynoecium in the same flower is
Plant reproductive morphology The primary mechanism used by flowering plants to ensure outcrossing involves a genetic mechanism known as self-incompatibility. Various aspects of floral morphology promote allogamy. In plants with bisexual flowers, the anthers and carpels may mature at different times, plants being protandrous (with the anthers maturing first) or protogynous (with the carpels mature first).[citation needed] Monoecious species, with unisexual flowers on the same plant, may produce male and female flowers at different times.[citation needed]
Foramen ovale (heart) The foramen ovale (from Latin, meaning "oval hole") forms in the late fourth week of gestation, as a small passageway between the septum secundum the ostium secundum. Initially the atria are separated from one another by the septum primum except for a small opening below the septum, the ostium primum. As the septum primum grows, the ostium primum narrows and eventually closes. Before it does so, bloodflow from the inferior vena cava wears down a portion of the septum primum, forming the ostium secundum. Some embryologists postulate that the ostium secundum may be formed through programmed cell death.[4]