Division of prokaryotes is not called mitosis .why?

The DNA of prokaryotes is not enclosed within a membrane, and is instead localized to a region called the nucleoid. This DNA acts as the prokaryote’s only chromosome, so the process of DNA replication is much quicker. After DNA replication, the original chromosome and its copy seperate. A cleavage furrow forms between the cell, the cell eventually pinches in half, and two identical daughter cells, each with an identical chromosome, are formed.

Explanation:

Note. You will find the image with the highlighted structure as an  

          attached file. You will also find a second file showing the location of

          these structures in a scheme.

Peyer's patches

Explanation:

Peyer's patches are anatomical regions located under the mucosa of the gastrointestinal tract, specifically in the lamina propria of the small intestine. These patches are nodules or cumulus of lymphatic tissue and other accessory cells, representing a huge part of the mucosa´s immunity system.

Peyer's patches belong to the group of lymphoid tissue associated with the intestine, composed of lymphoid follicles distributed along the gastrointestinal tract.

A lymphoid follicle is a cumulus or aggregate of lymphoid cells that do not have a well-defined structure nor organization. In general, these follicles are isolated from each other in the intestine. But in the terminal ileum (The last portion of the thin intestine) they get so close that they might form a plaque.  The Peyer´s patches are formed principally by lymphocytes B that synthesize immunoglobulin A, which has an important role in immunity.