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Endre Dobó
anatomical features:> Kerkring s valves (plicae circulares Kerkringi)
> approx. 1-cm-tall circular folds(cf. gastric rugae [folds], semilunar folds)
histological features:> intestinal villi (villi intestinales)
> approx. 1-mm-tall finger-like projections of themucous membrane into the lumen
Remarks: the microvilli are not considered to be specific feature, becausemicrovilli are present in another organs as well: e.g. ductus epididymidis, gallblader, kidney
functions> molecular breakdown of food> absorptions of small molecules
surface enlargement of small intestine> Kerkring s folds / valves (~ 1 cm)> intestinal villi (~ 1 mm)> microvilli (~ 1 µm)
> tunica mucosa (mucous membrane)
> lamina epithelialis mucosae
> lamina propria mucosae
> lamina muscularis mucosae
> tela submucosa
> tunica muscularis
> stratum circulare
> stratum longitudinale
> tela subserosa
> tunica serosa (serous membrane)
> lamina propria serosae
> lamina epithelialis serosae
in the retroperitoneal duodenum the serousa is replaced with adventia (!)
> the Kerkring s valve is formedby the relatively short longitudinalm. layer of the tunica muscularis
> in its core there is telatelasubmucosasubmucosa
lamina muscularis mucosae
telatela submucosasubmucosa
tunica muscularis
tunica serosa
inte
stin
alvi
lliin
test
inal
glan
ds(c
rypt
sof
Lieb
erku
hn)
lam
ina
prop
riam
ucos
ae
lam
ina
mus
cula
rism
ucos
ae
goblet cells
blood capillary
smooth muscle
enterocytes sloughing off
lymphatic capillary (lacteal)
smooth muscle
intraepithelial lymphocytes
enterocytes
striated border
enteroendocrine cells
lymphocytes
smooth musclegoblet cells
mitotic figures
Paneth cells
lamina muscularis mucosae
duodenum jejunum ileum
intestinal villi
intestinal glands
(crypts ofLieberkühn)
du
od
enal
du
od
enal
gla
nd
sg
lan
ds
lamina proprialamina proprialamina propria
folliculi lymphatici aggregati(Peyer s patches)
enterocytes
M cells
lymphatic follicle
cryp
tso
fL
ieb
erkü
hn
inte
stin
alvi
lli
gastricpit
gastricgastric
glandgland
stomach large intestinesmall intestine
lamina muscularis mucosae
inte
stin
alvi
lli
inte
stin
alg
lan
ds
inte
stin
alg
lan
d
lamina propria
goblet cell
enteroendo-crine cell
enterocyte
anatomical (macroscopic) features
> taeniae coli
> longitudinal layer of muscularis is split into 3 bands
> absent from the appendix and rectum
> haustra coli (colic sacculations)
> outpocketings between two semilunar folds
> appendices epiploicae / appendices omentales
> serosa-covered appendages contatining adipose tissue
general histological (microscopic) features
> (1) concomitant special properties:
> has intestinal glands (crypts of Lieberkühn)
> lacks intestinal villi
> (2) ratio of goblet cells to enterocytes is much larger in the largeintestine than in the small intestine
histological (microscopic) feature of appendix
> aggregated lymphatic follicles (folliculi lymphatici aggregati)
> are found as a complete ring in the wall of the appendix
(tela subserosa and / or lamina propria mucosae)
ileumappendix
vermiformis
mesentery meso-appendix
the last segment of the rectum
> proximal boundary
> beginning of anal / rectal column of Morgagni
(anorectal line)
(> pelvic diaphragm; levator ani muscle)
> distal boundary
> anus
> portions of anal canal (different covering epithelia)
> zona columnaris
> zonazona intermediaintermedia / / haemorrhoidalishaemorrhoidalis
> zona cutanea
external anal sphincter (striated m.)
middle rectal v.
venous plexus in the submucosa
adipose tissue
anal column
anal sinus
columnariscolumnaris--haemorrhoidalishaemorrhoidalis boundaryboundary
perineal skin
anus, skin
levator ani m. (striated m.)
internal anal sphincter (smooth m.)
longitudinal layer (smooth m.)
circular layer (smooth m.)
inferior rectal v.
haemorrhoidalishaemorrhoidalis--cutaneacutanea boundaryboundary