Development Animation - Heart Atrial Septation
Terms
atrial septation - Term describing the complex developmental formation of the interatrial septum, the wall between the right and left atria of the heart. In humans, this septation process begins in week 5 of development with the septum primum, a membranous extension on the dorso-cranial wall growing downward towards endocardial cushions. An opening remains as the foramen primum (ostium primum). The septum primum fuses with endocardial cushion, but cranially had begun to degenerate forming foramen secundum (ostium secundum). A later forming septum secundum on the ventro-cranial wall grows downward, but does not fuse with endocardial cushion, the remaining opening is the foramen ovale. Abnormalities of this process are called Atrial Septal Defects (ASD), a group of common (1% of cardiac) congenital anomalies occurring in a number of different forms and more often in females. The process of separating the ventricles is called ventricular septation.
ostium primum - (primary opening, first opening) In early heart development during atrial septation, the initial septum primum is incomplete leaving this initial opening between the left and right atria. Later the septum primum begins to degenerate forming a second opening, the ostium secundum.
ostium secundum - (secondary opening, second opening) In early heart development during atrial septation, the initial septum primum begins to degenerate forming this second opening between the developing left and right atria.
septum primum - (primary septum) In early heart development in the atrial wall a superior region in the midline extends downward, forming the initial incomplete separation (septation) of the right and left atria leaving an opening the ostium primum. This initial structure partially breaks down forming the ostium secundum and later fuses with the septum secundum. Note that complete functional and anatomical separation of the right and left atria occurs after birth with activation of the pulmonary system.
septum secundum - (secondary septum) In early heart development, atrial septation is completed by an atrial wall growth to the right of the initial septum primum. Note that complete functional and anatomical separation of the right and left atria occurs after birth with activation of the pulmonary system.
Source: UNSW Embryology Thanks to the late Prof William Larsen for allowing permission to use animations based on images from his textbook. (More? movie technical information)
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Cite this page: Hill, M.A. (2024, June 15) Embryology Development Animation - Heart Atrial Septation. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Development_Animation_-_Heart_Atrial_Septation
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G