Question

a. How can you differentiate between the serosa and the mucosa under the microscope? b. How is the muscularis of the stomach unlike the muscularis of the other regions of the GI tract. c. What is the main histological difference between the mucosa and the submucosa?

Answer 1

The gastro-intestinal tract consist of 4 layers:-

Mucosa

Submucosa

Muscularis propria

Serosa

(From inwards to outwards)

( a)Mucosa is a lining epithelium which includes glandular tissue, an underlying layer of loose connective tissue called the lamina propria, which provides vascular support for the epithelium, and often contains mucosal glands.

It mainly consists of plasma cells and lymphoid follicles.

Whereas serosa is the outermost layer of loose connective tissue which is covered by the visceral peritoneum. They mainly contains blood vessels, lymphatics and nerves.

(b) The muscularis in the stomach differs from that of other GI tract in that it has three layers of muscle instead of two. The three layers of smooth muscle consist of the outer longitudinal, the middle circular, and the inner oblique muscles.

The inner oblique layer of the stomach aids in digestion by grinding the food together with digestive juices.

(c) Submucosa is a loose connective tissue layer with larger blood vessels, lymphatics, nerves, and can contain mucous secreting glands whereas mucosa contains plasma cells and lymphatic follicles.