Recto-anal junction
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Rectum
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Anus
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
- Apocrine sweat gland
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
- Hair follicle
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Recto-anal junction
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Anal canal
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Muscularis externa inner layer
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Internal anal sphincter
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
Muscularis externa outer layer
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
External anal sphincter
The epithelium changes abruptly at the junction of the rectum (simple columnar) with the anal canal (stratified squamous moist); a more gradual transition occurs between the anal canal and anus. The inner circular layer of the muscularis externa thickens terminally as the internal anal sphincter. The outer longitudinal band blends with the adventitia. The external anal sphincter is composed of skeletal muscle. 40x
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