Serous Membrane
Definition
Synonym : - Serosa
Smooth membrane consisting of two layers of epithelial cells (as membranes), which secrete serous fluid.
The inner layer covers organs in bodily cavities and is called the visceral membrane;
A connective tissue
Outer layer of epithelial cells called the parietal layer which covers the body caivities (thoracid and abdominopelvic cavities)
Locations
Around the heart and lining the mediastinum - the pericardium
Lining the thoracic cavity and surrounding the lungs is referred to as the pleura
The one lining the abdominopelvic cavity and the viscera - peritoneum.
Visceral and parietal layers
Each serous membrane is composed of a secretory epithelial layer and a connective tissue layer underneath.
The epithelial layer, known as mesothelium, consists of a single layer of avascular flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid.
These cells are bound tightly to the underlying connective tissue.
The connective tissue layer provides the blood vessels and nerves for the overlying secretory cells, and also serves as the binding layer which allows the whole serous membrane to adhere to organs and other structures.
Development
From mesoderm of the embryo
The lateral plate mesoderm forms two layers bounding a cavity known as the intraembryonic coelom - splanchnopleure and somatopleure.
The splanchnopleure in contact with visceral organs within the body.
The somatopleure in contact with the body wall.
The intraembronic coelom which is covered with serous membrane derived from the splanchnopleure is divided and demarcated by the folding and development of the embryo and forms the serous cavities of the thorax and abdomen
