serosa
Meaning of serosa: Serosa is the smooth outer covering of many internal organs, formed by the same tissue that lines the chest and abdominal cavities.
Definition of serosa
Serosa is the outer, smooth surface layer covering many organs located within the chest and abdominal cavities, such as the stomach, intestines, and the surface of the heart and lungs. It is formed from the same tissue as the serous membrane that lines the surrounding body cavity, since the membrane folds back to cover the organ itself.
This outer layer secretes a small amount of thin, watery fluid that keeps its surface moist and allows the organ to move smoothly against the cavity wall or against neighboring organs, reducing friction during normal movements such as breathing, heartbeat, or digestion.
Because the serosa forms the outermost layer of these organs, it is often the layer examined to determine whether disease, such as inflammation or a tumor, has extended completely through the organ's wall to its outer surface, information that can affect how a condition is staged or understood.
Also known as
Used in a sentence
Pathology confirmed that the tumor had extended through the bowel wall to involve the serosa.
Good to know
Involvement of the serosa is often specifically assessed when staging a tumor, since disease reaching this outermost layer generally carries different implications than disease confined to the deeper layers of an organ's wall.
Word origin
Where “serosa” comes from
Formed from Latin serum, meaning whey or watery fluid, combined with the suffix -osa, meaning full of or characterized by.