4.1.1 POJA-La0267+4108. Intermediate zone of the anal canal (human)
4.1.1 POJA-La0267+4108
Title: Intermediate zone of the anal canal (human)
Description: Stain: (A) Hematoxylin-eosin; (B) Scheme.
The intermediate zone (2) is a transition zone between the colorectal mucosa (1) and the skin epidermis, i.e. a transition from non-keratinizing simple epithelium with goblet cells to a non-keratinizing multilayered squamous epithelium towards the keratinizing epidermis epithelium.
The lamina propria tissue in (2) is richly vascularized and comprises the convoluted haemorhoidal arterio-venous anastomoses or plexus which usually have a thin wall.
(4) Inner smooth muscle layer forming part of the sphincter that is illustrated more elaborately in figure (B).
(5) Musculus sphincter ani internus.
(6) Outer longitudinal muscle layer.
(7) Striated musculus sphincter ani externus. Note that the colorectal mucosa is folded into many crypts, but no villi (no resorption activity).
Anal sinuses are observed beyond the intermediate zone (8).
Keywords/Mesh: colon, rectum, anal canal, skin, haemorrhoid plexus, histology, POJA collection
Title: Intermediate zone of the anal canal (human)
Description: Stain: (A) Hematoxylin-eosin; (B) Scheme.
The intermediate zone (2) is a transition zone between the colorectal mucosa (1) and the skin epidermis, i.e. a transition from non-keratinizing simple epithelium with goblet cells to a non-keratinizing multilayered squamous epithelium towards the keratinizing epidermis epithelium.
The lamina propria tissue in (2) is richly vascularized and comprises the convoluted haemorhoidal arterio-venous anastomoses or plexus which usually have a thin wall.
(4) Inner smooth muscle layer forming part of the sphincter that is illustrated more elaborately in figure (B).
(5) Musculus sphincter ani internus.
(6) Outer longitudinal muscle layer.
(7) Striated musculus sphincter ani externus. Note that the colorectal mucosa is folded into many crypts, but no villi (no resorption activity).
Anal sinuses are observed beyond the intermediate zone (8).
Keywords/Mesh: colon, rectum, anal canal, skin, haemorrhoid plexus, histology, POJA collection