Primitive atrium

Primitive atrium is a term used in embryology to refer to the initial stage of the development of the atrium in the heart. The primitive atrium is a part of the primitive heart tube, which is the earliest stage of heart development in the embryo. The primitive atrium later gives rise to the two atria of the adult heart.

Etymology

The term "primitive atrium" comes from the Latin "primitivus", meaning first or original, and "atrium", which in anatomical terms refers to a chamber or cavity. In this context, it refers to the first, or original, stage of the atrium in heart development.

Development

The primitive atrium forms during the third week of embryonic development. It originates from the cranial part of the primitive heart tube, which itself is derived from the mesoderm layer of the embryo. The primitive atrium initially forms as a single chamber, but it soon divides into the right and left atria.

Related terms

• Primitive ventricle: The initial stage of the development of the ventricle in the heart.
• Primitive heart tube: The earliest stage of heart development in the embryo, from which the primitive atrium originates.
• Atrium (heart): The two upper chambers of the heart, which receive blood from the veins and pump it to the ventricles.

See also

• Heart development
• Embryology
• Cardiac anatomy

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