This image shows the
mucosa at the anorectal junction (ARJ) boundary
between the anus and the rectum. The rectal mucosa (RM)
(to the left of the red arrow) is similar to that of the colon, consisting
of: (1) a simple columnar epithelium rich in goblet cells with mostly unstained
cytoplasm covering the surface as well as the lumen of tubular intestinal
glands, the crypts of Lieberkuhn (Cr); (2) a
lamina
propria (LP) of loose connective tissue; and (3) a muscularis
mucosae (MM) of smooth muscle cells. The anal
mucosa (AM) consists of a nonkeratinizing stratified squamous epithelium
supported by a lamina
propria (LP) of loose connective tissue.
Aggregations of lymphoid
cells (LC) may be present in the connective tissue of both the rectal
and anal mucosae.
