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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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-1-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-2-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-5-ping.png)
- 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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-6-ping.png)
- 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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-3-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-4-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-9-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-7-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-10-ping.png)
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 <p>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</p>](https://digitalhistology.org/wp-content/uploads/2017/10/Or.Dig_.Tub_.LgI-13-8-ping.png)
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