The Mouse Adult Gross Anatomy Ontology and Mammalian Phenotype Ontology are downloaded weekly from the Mouse Genome Informatics databases at Jackson Laboratories (ftp://ftp.informatics.jax.org/pub/reports/index.html). For more information about these ontologies, see the MGI Publications Page at http://www.informatics.jax.org/mgihome/other/publications.shtml.
a heart with 3 atria, is in which either the left or right atrium is divided into 2 parts by a fold of tissue, a membrane, or a fibromuscular band that may vary significantly in size and shape, appearing similar to a diaphragm or funnel-shaped, bandlike, entirely intact (imperforate) or contain 1 or more openings (fenestrations) ranging from small, restrictive-type to large and widely open