Rectum
- dilated distal portion of alimentary cana;
- similar to large intestine in having straight glands, many goblet cells
- distinguished from rest of alimentary tract by transvers rectal folds
Anal Canal
- anal glands ectend into submucosa and muscularis externa
- stratified columnar epithelium becomes stratified squamous in distal portion
- submucosa contains ramifications of superior rectal artery, venous plexus
- longitudinal muscle forms one sheet
- muscularis mucosae diasappears at rectoanal margin
- circular layer of muscularis externa thickens to become internal anal sphincter
|