Proctodeum
Encyclopedia
A proctodeum is the back ectodermal
part of an alimentary canal. It is created during embryogenesis
by a folding of the outer body wall. It will form the lower part of the anal canal
, below the pectinate line
, which will be lined by stratified squamous non-keratinized
(zona hemorrhagica) and stratified squamous keratinized
(zona cutanea) epithelium. The junction between them is Hilton's white line
.
Germ layer
A germ layer, occasionally referred to as a germinal epithelium, is a group of cells, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sponges produce two or three primary tissue layers...
part of an alimentary canal. It is created during embryogenesis
Embryogenesis
Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...
by a folding of the outer body wall. It will form the lower part of the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....
, below the pectinate line
Pectinate line
The pectinate line is a line which divides the upper 2/3s and lower 1/3 of the anal canal. Developmentally, this line represents the hindgut-proctodeum junction....
, which will be lined by stratified squamous non-keratinized
Stratified squamous epithelium
A stratified squamous epithelium consists of squamous epithelial cells arranged in layers upon a basement membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity...
(zona hemorrhagica) and stratified squamous keratinized
Stratified squamous epithelium
A stratified squamous epithelium consists of squamous epithelial cells arranged in layers upon a basement membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity...
(zona cutanea) epithelium. The junction between them is Hilton's white line
Hilton's white line
Hilton's white line is a boundary in the anal canal.Below it, lymphatic drainage is to the superficial inguinal nodes.A landmark for the intermuscular border between internal and external anal sphincter muscles...
.
External links
- http://trc.ucdavis.edu/mjguinan/apc100/modules/Reproductive/bird/overview0/overview.html
- http://www.embryology.ch/francais/sdigestive/gesicht08.html