Anatomy of Intestine in Domestic Animals

Gross, histological and

developmental  Anatomy of

intestine in domestic animals

TOPICS TO BE DISCUSSED

1.

Gross Anatomy

2.

Histology

3.

Embryology

Gastrointestinal tract

Rima oris to anus

1.Oral cavity- 

tongue,teeth,salivary glands,hard

palat and soft palat

2.Pharynx

3. Esophagus

4.Stomach

5.Intestine

6.Liver

7.Pancrease

8.Spleen

Introduction

•

The intestine plays an important role in the digestion and

absorption of various nutrients.

•

Small intestine : chemical digestion and absorption.

•

Large intestine: absorption of water and excretion.

•

Intestinal juice- 

‘Succus entericus’- 

is derived from the

intestinal glands/ crypts of lieberkuhn  and duodenal glands.

•

Intestinal juice contains hormones, digestive enzymes, mucus

substances to neutralize hydrochloric acid coming from the

stomach.

•

The mucus secreted by the goblet cells  lubricates and

protects the mucosa.

(Frandson, 1986, Getty 2012)

Intestine :

The part of alimentary canal which extend from 

‘

pylorus of stomach to anus’. 

It consist

of two parts:

Proximal part- small lumen – Small intestine

          Distal part -wider lumen- Large intestine

Small intestine: 

Part of the gastrointestinal tract between the stomach and large

intestine.

    3- distinct regions –duodenum, jejunum, and ileum.

The first part duodenum is attached by a short fold, the 

Mesoduodenum

, while

remainder is attached by 

Mesentery 

and is divided into jejunum and ileum. The line

of demarcation is arbitrarily set at the free edge of the 

ileocecal fold

. The

duodenum is initimately related postionally with liver to which it is connected by

Hepatoduodenal ligament

. Duodenum also receives bile duct and pancreatic duct.

large intestine:

Extend from the termination of ileum to anus. It is divided into

cecum, colon, and rectum.



Cecum

 is a blind sac with an opening into beginning of the colon.



Colon

 begins at cecocolic orifice to rectum at pelvic inlet. There is no

line of demarcation between colon and rectum; the 

plane of pelvic

inlet may be demarcation line.



Rectum

 is extends from pelvic inlet to anus.



Anus

- terminal part , below root of tail

Gross Anatomy: Ruminants

Topography

: lies entirely to 

right side 

of median plane chiefly in contact

with right face of rumen and attached to sub lumber region by

common mesentery.

Small intestine:

•

Convoluted tube extend from pylorus to ileo-cecal orifice.

        Biometry:

•

Average length: 39-42 meters

•

Duodinum- about 1.2 meters

•

Jejunum- about  38-40 meters 

(longest segment

)

•

Ileum-  about: 0.8 meters

•

Average Diameter: 5-6 cm

•

The jejunum was the longest and widest segment of small intestine.

Duodinum

Three parts:

1.Cranial part- 

form

 ‘

Ansa

sigmoidea’

 S

-shaped curve on

visceral surface of liver.

2. Descending part: 

 goes up to

almost tubercoxae and form

caudal

/

illiac flexor

. Passing

right to left around root of

mesentery

.

.

 3. Ascending part: 

extend

forward  and terminate at

duodenojejunal flexor which

lies on 

left side of cranial

mesenteric artery

.

-

Bile duct opens in 2

nd

curve of ansa sigmoidea,

50-60 cm 

from pyloric end.

-

Pancreatic duct opens 80-

90 cm from pylorus 

or 30

cm

 further back from bile

duct.

-

In 

sheep/ goat 

bile and

pancreatic duct join

together and open into

duodenum about 

25-40/20

cm 

from pylorus.

Jejunum



Arranged in numerous very

close coils, ‘

U’ shaped tubular

loops

/ festoons by

attachment of mesentery.



Lies chiefly in space

bounded medially by right

face of ventral sac of rumen

and  right abdominal wall,

dorsally by large intestine and

anteriorly by omasum and

abomasum

Terminal part of jejunum

leave the edges of mesentery

and runs forward between

cecum and colon.

Line of demarcation 

between

cecum and colon is 

opening

of ileum into cecum.

Ileum

Large Intestine :

10-11 meters

Avg diameter- 15 cm

Lies between layers of common

mesentery in the

 dorsal part of

the right half of the abdominal

cavity.

Caecum:

(0.8m in length and 12 cm in

diameter) 

cylindrical blind sac

goes up to pelvic inlet

2 orifices- 

ileocaecal –small,

caecocolic- large

Caecum is directely continuous

infront with colon.it usually

near ventral end of last rib.

Colon

•

10 meter in 

 length, 12 cm in diameter which diminishes in course of

proximal loop up to 5 cm



largest part 

of Large Intestine



From caecocolic orifice to rectum lies between layers of mesentery

,coiled upon itself in such a manner as to form number of 

elliptical

convulsions.



3 parts

•

Ascending 

(loop part)- longest part

•

Transverse part

•

Descending part

A. Ascending colon :

a.Proximal loop

: runs 

Cranially-

Caudally -Cranially -Ventrally

b.Spiral loop

: 

2 centripital coils

,

a central flexur and 2 centrifugal

coils ( in 

sheep/ goat :3-3)

Form a disc shape situated in

right lateral upper abdomen

c. Distal loop

: terminal portion

of centrifugal part of spiral loop,

continuous with transverse

colon.

B.Transverse colon

: 

Passes from

right to left around 

the cranial

mesenteric artery.

C. Descending colon 

: 

Become

continuous with rectum.

A

B

C

Artery

a

b

c

Descending

Rectum

•

30 cm

•

2 parts:  Cranial – Covered by peritoneum and variable in position

•

               Caudal -  

Retroperitoneal

 and form 

ampulla recti

•

 Wall presents constriction and dilation.

Anus (Anal canal)

•

Terminal part of GIT situated 

below root of tail 

(below about

4

th

 coccygeal vertebrae)

•

Have 02 sphincter- 1. sphincter ani internus-smooth muscle

2. sphincter ani externus-

skeleton muscle

Intestine of Horse

Small intestine

22-24 meter long, (7.5-10 cm)

Duodenum

- about 1m

Jejunum

- about 20 m

Ileum 

- about 1 m

Location 

-Lies in Dorsal part of 

left half

of abdomen, coils reach to floor and

pelvic cavity.

Duodenum

Horse shoe shape

3 parts- 

1. Cranial-   

    shape

curve

  2.Descending-    fixed

with right dorsal colon

               3.Ascending-      fixed

with base of caecum

-concavity of 2

nd

 curve have

hepeto-pancreatic ampulla

/

diverticulum duodeni

/

opening

of bile and pancreatic duct

(cm from pylorus)

S

Jejunum and ileum- 

No distinction

between two(Last meter is the ileum)

     -Numerous coils

intermingled with small colon

Large intestine

Characterised by 

bands and sacculations

Caecum

It is very big comma shaped cul-de-sac

situated 

from right iliac and sub-

lumber region to abdominal floor

caudal to xyphoid cartilage

03 parts- 

base,body and apex

-

Have both 

ileocaecal and cecocolic

orifice 

in lesser curvature of base

situated 5-7.5 cm apart. In between

the two 

Intervening fold

 is present

-

Both opening also have 

sphincter ilei

and sphincter caeci

04 longitudinal

bands (

Teniae

ceci) 

and 04 rows

of sacculation

(

Haustra ceci)

Caecum

Right side

Colon of horse

•

02 parts

1.

Great colon (Ascending part)

2.

Small colon (descending part)

Great colon

Begins from cecocolic orifice (at base of caecum)and

terminate by joining small colon behind the saccus

caecus of stomach.

Have 

04 parts and 03 flexures

1.

Right ventral

2.

Left ventral

3.

Left  dorsal

4.

Right dorsal

1.

Right ventral

From the base of caecum (at last rib)

up to xyphoid cartilage, than it

bends sharply to right side form

sternal flexure

2. Left ventral- 

passes caudally up

pelvic inlet and bends dorsally to

form- 

pelvic flexure

3.Left  dorsal- 

passes dorsally or

lateral to left ventral and

reach up to diaphragm and

bends  to form

Diaphragmatic flexure

4.Right dorsal- 

passes dorsal to

right ventral colon and reach

to base of caecum.

it turn to left and dorsally behind

left sac of stomach, here it

becomes constricted, and

joins small colon below the

left kidney.

•

Small colon- 

from termination of large colon to

rectum.

•

Lies in space between stomach and pelvic inlet,

dorsal to left part of great colon

•

Mingled with small intestine but easily

distinguished by 

02 rows of bands and

sacculations

•

Attach to sub lumbar muscle by mesocolon and to

termination of duodenum by duodinocolic fold of

peritoneum

•

Arranged in coils

Caliber of colon:

•

Great colon- 

at its origin about 

5-7.5

 cm- Soon

increase to 20-25 cm for ventral parts- beyond

pelvic flexure diameter reduced to about 8-9 cm

.-

towards the diaphragmatic flexure the caliber

rapidly increases, and reaches its maximum in last

part (Right dorsal)- 

50 cm

. This succeeded by a

funnel shaped terminal contraction.

•

Small colon- 

diameter about 

7.5-10

 cm

•

Rectum: as ox

•

Applied: 

at 

pelvic flexure 

chances of obstruction of

dry faecal material /indigestion causes colic

intestine- Dog

•

Duodenum-

Retrograde/1

st

 part

•

from pylorus passes caudally

and somewhat dorsally to

visceral surface of liver,near

pelvis turn medially (illiac

flexure)and passes cranially.

Recurrent/2

nd

 part

From illiac flexure passes

cranially and bends ventrally

to  join jejunum.

Bile duct and smaller pancreatic

ducts open- 5-8 cm from

pylorus

Larger pancreatic duct 

opens

2.5-5 cm further from bile

duct or 7.5-13 cm from

pylorus

•

Jejunum-

6-8 coils between liver and

stomach

Ileum-

Ileum 

opens into colon 

at ileal

opening and there is ileal

papilla/

ileocolic valve

-Ileum communicate only with

colon.

-ileocolic and caecocolic orifices

close and caecum present as a

diverticulum of colon

Caecum-

cork screw shape

bands and sacculation absent

Caecum

Caecum

Stomach

Rectum

Colon of dog

•

bands and sacculation absent

•

03 parts

•

1. Ascending- cranially go up to pylorus

•

2. Transverse – short

•

3.Descending- up to ventral surface of left kidney

Rectum of dog

•

anal glands 

present

•

02 lateral anal sacs present which contains dirty gray, fatty

substance and unpleasant odour

•

Skin which lines these pouches contains 

coils glands

•

Further caudally skin contains large 

sebacious Circumanal

glands

•

Rectum almost completely covered by peritoneum

Pig

•

Small intestine:

•

Duodenum: cranial,descending and ascending

•

Opening of bile duct 2.5 cm from pylorus and pancreatic

duct- 10 cm

•

Caecum

- 

cylindrical shape

03 longitudinal muscular bands (teniae)

03 rows of sacculations (haustra)

Opening of ileum and colon apart.

Franulum ilei- 

a fold of mucous membrane passes each side of

ileo-caecal opening

Colon

•

lies chiefly to left of median

plane caudal to stomach

•

03 parts

•

1. 

Ascending colon- 

arrange in 3

close, 

double spiral coils in

relation with floor of abdomen,

ventrally runs cranially up to

stomach and turns left as

•

2. 

Transverse colon- 

which

passes caudally as

•

3. Descending colon- 

reach to

pelvic inlet

•

02 teniae and haustra present in

ascending colon

Ox

Horse

Dog

Pig

Species differentiation: Small  intestine

Small  intestine

 Large intestine

Large intestine- cecum:

Large intestine- colon :

Large intestine- colon and rectum 

:

Ox

Horse

Dog

Pig

Attachments :ox

Duodenum: 

Cranial part 

of duodenum- 

lesser omentum

•

Descending 

part and caudal flexure attach dorsally to 

mesoduodenum

 and

descending part attached ventrally to superficial wall of omental bursa.

•

Ascending

 part attached to descending colon by 

duodenocolic ligament 

and to

proximal and distal loop of ascending colon by adhesions around root of

mesentery.

Jejunum: 

Usually lies in supraomental recess 

(mesenteries)

Ileum : 

Cranial part is adherent to cecum.

Cecum : 

Cranial 2/3

rd

 adherent to right side of mesentery. Dorsally to proximal

loop of colon by 

cecocolic fold

, ventrally to ileum by 

ileocecal fold.

Colon 

:   Spiral loop lies in 

between layers of mesentery

. The proximal and distal

loop and cranial part of descending colon adherent to cranial part of cecum

and ascending duodenum in a fat filled mass around root of mesentery.

Rectum: A short 

mesorectum

 near sacral promontary.

Attachments :Horse

Duodenum/ fixed part :  

by 

mesoduodenum

, cranial part to liver and descending

part to right dorsal colon, base of cecum, right kidney and sublumbar muscles.

Jejunum and ileum /mesenteric part:  

by mesentery to dorsal abdominal wall.

Ileocecal fold 

attaches ileum to lesser curvature of cecum.

.

Cecum :  

Base attach dorsally by connective tissue and peritoneum on ventral

surface of pancrease and right kidney.

 Body 

attached dorsolaterally to first

part of colon by 

cecocolic fold. Apex is free

.

Colon 

: Right ventral part of great colon attached to lesser curvature of cecum by

2 layers of peritoneum, which form 

cecocolic fold

. Right parts and left parts

are united by peritoneum on either side.  The transverse colon attached by

peritoneum to pancrease dorsally and base of cecum laterally.

Small colon attach to sublumber region by

mesocolon 

and to termination of

duodenum by narrow duodenocolic fold.

Rectum

:

 Mesorectum 

, continuation of mesocolon.

Vessels and Nerve

Small intestine: 

(beginning of duodenum is supplied by branches of 

Celiac

artery.

 Other portion is supplied 

by Cranial mesenteric artery

).

Cranial part of duodenum- right gastric and right gastroepiploic artery

Descending part- cranial and caudal pancreatoduodenal artery

Ascending part- branch of cranial mesenteric artery from left side and from

middle colic artery

Jejunum – jejunal arteries (branches of cranial mesenteric artery). In ox a

collateral branch 

originates from concave surface of cranial mesenteric

artery and passes obliquely across the mesentery to rejoin the cranial

mesenteric artery. 

Collateral branch absent in sheep and goat.

Ileum – 2 arteries: ramus ilei mesenterialis come from ileocolic artery and

ramus ilei antimesenterialis  is termination of cecal artery. Both of which

anastomose with terminal branches of cranial mesenteric artery.

Veins 

of small intestine are generally satellites of arteries but gastroduodinal

and caudal mesenteric vein are branches of portal vein which extends

from liver to terminal branches, the cranial and caudal mesenteric veins.

Large intestine

:

(

cranial and caudal mesenteric arteries)

Small middle colic artery arise from cranial surface of cranial mesenteric artery

and supply transverse and descending colon.

The ileocolic/ileocecocolic artery is a large trunk that gives colic branch which

supply proximal, distal and coiled loop

Cecal artery runs in ileocecal fold, supplies the cecum and ileum.

Branches of ileocolic vein are satellites of branches of ileocolic artery. The caudal

mesenteric vein gives off middle colic and left colic veins.

Rectum:

cranial rectal artery from caudal mesenteric artery  

and by several short

middle rectal branches from 

urogenital artery. 

The anal canal supplied by

terminal branches of cranial and middle rectal artery.

 Nerve supply

The intestine gets 

sympathetic fibres 

from celiac, cranial mesenteric and caudal

mesenteric ganglions and 

parasympathetic fibres from vagus 

and pelvic

splanchnic nerves. Rectum also innervated by caudal rectal nerve

.

Histology

General structural pattern of tubular organs

1. Tunica Mucosa

a. Lamina Epithelialis

b. Lamina Propria

c. Lamina Muscularis

     2. Tunica Submucosa

3. Tunica Muscularis

4. Tunica Serosa

Small intestine

Tunica mucosa:



Mucosal folds 

(plicae circularis

present)  

(Banks,1981)



Villi

 (finger like projection) are

most characterstic feature.



Microvilli

 are present



Simple columnar epithelium 

with

numerous goblet cells.

Number of goblet cells dicrease at

the tip of villi.



Intestinal gland (crypts of

leiberkuhn) 

throughout intestine

Simple tubular type

, opens

between villi

     Lined by 

5 cell types

:

1. Epithelial columnar cells

2. Undifferentiated cells

3.

Paneth cells

4.

Enteroendocrine cells

5.

Goblet cells

Undifferentiated cells

: Multiply

,differentiate and migrate into villus

giving rise to columnar absorptive cells

and goblet cell.

Paneth cells /acidophilic granular cells:

Pyramidal shape 

at base with

acidophilic granules

. Produces

peptidases and lysozyme.

Enteroendocrinecells: 

Secretes

gastrin,

secretin, cholicystokinin and gastric

inhibitory polypeptide.

Difficult identification in 

H&E

. Many

cells affinity to 

silver stain 

so known as

Argentaffin/ argyrophilic cells 

and

some demonstrated with potassium

dichromate solution so called

enterochromaffine cel

l.

They present 

throughout

 glandular

region of gastric mucosa and

continuing into small and large

intestine.

In lining of GIT , 

Zonula Occludens

(tight junction) / junctional complexes

seals off the upper part of epithelium

which 

Prevent leakage of material

from the lumen into subepithelial

space and prevent contents diffusing

into lamina propria without going

through cells.

Lamina propria

Form the 

core of villi 

and surrounds

the intestinal glands.

A single lymphatic capillary; 

lacteal 

is

located in the centre of lamina propria

with in the villus.

A 

single arteriole 

courses into the

villus.

Villi act as pumping stations 

for

moving blood and lymph into general

circulation.

Lamina muscularis : 

inner circular

outer longitudinal smooth muscle,

thin and 

incomplete except dog.

Submucosa:

Brunner’s gland/ Submucosal gland/

duodenal glands:

Branched Tubuloalveolar.

Duct perforate the muscularis mucosa

and mucous membrane.

Nature 

: 

Mucous

 in 

ruminants and 

dog

Serous

 in 

horse and pig

Mixed

 in 

cat

-Secretory product lubricates the surface

epithelium and provide 

protection

 from

acidic gastric chyme.

They are confined to 

proximal portion of

duodenum

 (60-70cm in sheep and 20-

25cm in goat) or

 close to pylorus in dog,

in pig extend 3-5 meter from pylorus.

In

horse they extend well into the

jejunum

( first 6-7 m) . 

first 4-4.5 m in ox

Submucosal gland don't extend full

length of duodenum in sheep/ goat

and carnivores, 

whereas in cattle,

horse and pig extend into jejunum

.

Peyer's patches often considered an

identifying feature of ileum.

Submucous plexus/Meissner's plexus

The nerves of this plexus are derived

from the 

myenteric plexus 

which itself

is derived from the plexuses of

Parasympathetic Nerves

. Branches

from the 

myenteric plexus 

perforate

the circular muscle fibres 

to form the

submucous plexus

. Ganglia from the

plexus extend into the muscularis

mucosae and to the mucous

membrane.

.

Gut- Associated lymphatic

Tissue(GALT):

Includes:

(Trautmann and Fiebiger,

1957)

1.

Solitary and Aggregated lymphatic

nodules

( Peyer’s patches)

2.

Intra and interepithelial

lymphocytes

3.

Diffusely arranged lymphocyte in

lamina propria

4.

Plasma cells

5.

Macrophages

Solitary and Aggregated lymphatic

nodules(peyer’s patches)

Solitary lymphatic nodules 

are present

in 

whole GIT 

but 

aggregated 

lymphatic

nodules occurs 

only in small intestine

(more conspicuous in ileum)

In ruminants 

peyer’s patches 

large

 and

distinct. No. 

18-40

 in adult cattle. The

patches near ileocecal junction may

extend into large intestine.

In horse: 

begins 1 meter from pylorus. No.

100 to 200  

and larger ones occur in

terminal parts, where one patch may

have 17-38 cm x 5-25 cm in

dimension

.

Dog: 

Elliptical

 in outline but last one is

band like, no. About 

20

, begins in

duodenum and  reach up to ileum. 10-

40 cm in young dog.

Pig:  

B

and like,16-38

 in no., starts 20-50 cm

from pylorus and last long one is

continued in cecum.

Largest in cattle and most numerous in

horses.

The  

follicle /nodule- associated

epithelium 

covering the

dome(elevated region overlying

lymphatic nodules) 

lacks goblet cells

but includes 

M- cells 

that have

numerous microfolds of their luminal

surface.

M-cell

- typically enfold groups of

lymphocytes and occasionally

surround macrophages and dendritic

cells.

Nickel et al, 1973

mentioned  that  the 

lymphocytes

 present

in large number in lamina propria and

between the epithelial cells, 

were the first

line of defence 

against microorganisms

entering the intestinal wall.

Tunica muscularis

:

Inner circular, outer

longitudinal

Thickest in horse

Myenteric plexus 

between 2

muscle layers

Tunica serosa:

layer of loose connective

tissue covered by

Mesothelium

   Duodenum                        jejunum                                  ileum

Large intestine:

Site for microbial action on ingesta,

absorption of water, vitamin 

and

electrolyte and 

secretion of mucus

.

Characterized by:

Absence of villi

/ mucosa is smooth

Longer less coiled, simple tubular

intestinal glands with many goblet

cells.

Absence of paneth cells

Absence of plicae circularis 

but

longitudinal folds are present

Increase number of solitary

lymphatic nodules.

Cecum :

In 

ruminant, dog 

and pig-

lymphatic nodules

numerous around 

the ileal

ostium.

In horse and cat

concentrated near the 

apex

of cecum.

Colon:

Number of 

goblet cells increase 

than

small intestine. Intestinal glands may

extends into submucosa.

In 

horse and pig- 

outer longitudinal layer

of tunica muscularis of cecum and colon

forms large, flat, muscle bands

containing numerous 

elastic fibres-

taenia ceci and taenia coli

.

Rectum :

Like cecum and colon mucosa is smooth

Increase goblet cells

In cattle & horse: 

Rectal wall thicker than

colon

In carnivores:  outer logitudinal layer of

tunica muscularis is thickned.

:

Cranial portion is covered by

serosa (peritoneum) 

while

retroperitoneal

 portion by tunica

adventitia.

Near junction with anal canal –

rectal columns.In dog rectal pits

are found

Anal canal

At anorectal junction simple

columner epithelium abruptly

change to non keratinized

stratified sequamousEpithelium

.

Mucosa smooth and 

lacks glands

in ruminants and horses , but in

pig and carnivores 

modified

sweat glands

 , anal glands occupy

propria submucosa.

Embryology

The primary tissue of entire

digestive system is 

Endoderm.

The rapidly expanding embryonic

disc

 begins 

to fold 

into a cylindrical

embryo, its 

Gut- endoderm

participates as a component layer.

The 

primitive, tubular gut

differentiates into alimentary canal

which has 3 chief segments:

Mouth, Pharynx and Digestive

tube

.

The digestive tube includes

Esophagus, Stomach and Intestine

( Mcgeady, 2006, Arey, 1954 )

•

The digestive canal proper consists of:

 (1) An internal tube of 

Endoderm

, which become 

epithelial

 lining

including 

glandular ingrowths

(2) An investing layer of 

Splanchnic Mesoderm 

that specializes into

thick supporting wall 

( lamina propria,submucosa, muscularis

mucosa and serosa ) .

•

The mucosal linning expands 

faster

 than outer wall, so becomes

thrown into folds.

•

Circularly arranged muscle layer of tunica muscularis 

appear first

then longitudinal

.

Development of the primitive

digestive tract commences with the

cranial, caudal and lateral folding 

of

embryonic disc and the

incorporation of dorsal portion of

the primitive yolk sac into the

embryo.



Cranial portion of the tract formed

with in the head fold is termed

foregut



 Part formed with in the caudal

fold is 

hind gut



 Segment between foregut and

hind gut, which is continuous with

the yolk sac is the 

mid gut

.

         McGeady 

et al 

(2006)

•

Intestine is formed from that portion of foregut which is caudal to

developing stomach and from entire midgut  and hindgut

•

Foregut

 – Mouth, pharynx, esophagus, stomach, liver, pancreas

and  

Descending duodenum

•

Mid gut- 

Ascending duodenum, jejunum, ileum, cecum, ascending

colon and transverse colon

•

Hind gut- 

Descending colon and rectum

(K.S.Roy 2009, Mcgeady 

et al 

2006, Arey, 1954)

Initially Intestine is as a

simple tube beginning at

stomach and ending in cloaca.

Mid gut together with its

mesentery elongates forming a

Midgut Loop

, which further

divided into Ascending and

descending.

As loop increase in

length, it outgrows its available

space in abdominal cavity 

and

occupies part of extra-

embryonic coelom called

umblical sac.

During development

following process can be

observed-

1.

Rotation

2.

Herniation  and coiling

3.

Re-entry and placement

4.

Completion

These changes occurs in 

3

rd

to 4

th

 weak

of gestation in

ruminants, pig and dog

1. Rotation:

Midgut loop occupies a

position in extra- embryonic

coelom. it 

Rotate clockwise 

,

viewed dorso-ventrally.

Cranial mesenteric artery

act as axis.

Initial rotation

 180

0

Mcgeady 

et al 

(2006)

          Arey, (1954

)

2. Herniation and coiling



Elongating Intestinal loop can

no longer be contained with in

slower growing abdomen

, it

begins to 

escape into Umblical

Cord.



Duodenum and descending

colon not entering in cord

.



Continue elongation of

herniated small intestine leads

to 

extensive coiling 

as compare

to large intestine

Mcgeady 

et al 

(2006)

Arey, (1954)

Re-entry and placement



When abdominal cavity

increase sufficient size and

liver decline in growth rate

, so

intestine re-enter.



Small intestine first to re-

enter.



The returning coils first fill the

available space on the left

side whereas later coils locate

in right half of abdominal

cavity. This completing a

rotation of 

total 270

0

.

Mcgeady 

et al 

(2006)

                   Arey, (1954)

Completion



The original 

Caecal Bulge 

grows

and make definite blind sac which

demarcate small intestine and large

intestine

.



   The terminal portion of

intestine/ rectum is derived from

subdivision of cloaca 

(

dorsal rectum

and ventral bladder, urogenital sinus

)



Component of large intestine

showing 

simple

 ascending colon in

carnivores



Coiled

 ascending colon in

ruminants



Cone-shaped

 arrangement in 

pig



Enlarged cecum 

and dorsal ,ventral

components of ascending colon in

horse

Histogenesis

•

Villi

 begins to appears at 

8

th

 weaks

.

•

Intestinal glands arise as tubular outgrowth of epithelium at end of 3

rd

month.

•

Intestinal glands 

in large intestine  were observed in buffalo fetus at 

198

days 

of gestation. 

(Singh 

et al 

,2012)

•

Brunner’s glands 

appeared at 

14.2 cm CVR 

stage in goat

.(

Ramkrishna  and

Tiwari ,1979)

•

Lymph nodes and payers patches present at 5

th

 month.

•

Appearance of lymphocyte was initiated from day 99 in lamina propria of

small intestine and 

payer’s patches 

appeared in ileal submucosa at 

106

days old fetus of black Bengal goat 

(Gautam 

et al 

2016)

•

Peristalsis

 observed at 

11

th

 weak

•

Meconeum

 begins to collect in intestine after 

3

rd

 months

.  

(Arey, 1954)

Developmental anomalies

1. 

Imperforate anus

: Incomplete separation of rectum.

2. 

Omphalocoele

: Failure of normal return of intestine.

3. 

Situs inversus: 

Complete reversal of normal course of rotation of

intestine.

References

•

Frandson R.D., Lee Wilke W. and Fails A.D.(1986). Anatomy and

physiology of Farm Animals. 7

th

 Edition. Wiley Blackwell Publication.

•

Nickel R., Schummer A., Seiferle E.and Sack W.O.(1973). The Viscera of

Domestic Mammals. Verlag Paul Berlin Publication.

•

Getty R.(2012). Sisson and Grossman’s The Anatomy of the Domestic

Animals. 5

th

 Edition, East West Press Private Limited.

•

Roy K.S. (2009). Foundation of Veterinary Embryology. Kalyani

Publishers.

•

Arey L.B.(1954). Developmental Anatomy- A Textbook and Laboratory

Manual of Embryology. 6

th

 Edition, W.B. Saunders Company.

•

Dellmann & Eurell J A (1996). Textbook of Veterinary Histology. 5

th

Edition, Willium & Wilkins Publication.

•

Eurell J A & Frappier B L (2006). Textbook of Veterinary Histology. 6

th

 Edition,

Blackwell Publishing.

•

Gautam A.K. and Mishra U.K. (2016). Development of intestinal immunity in

prenatal stages of black bengal goat. Journal of cell & Tissue Research 16: 5527-

5530.

•

McGeady T.A., Quinn P. j., FitzPatrick E.S. and Ryan M.T. (2006).

Veterinary Embryology. Blackwell Publishing

•

Rajesh, R. and R. L. Bhardwaj (2009) “Biometrical studies on the intestine

•

and adjoining lymph nodes of Gaddi sheep” Ind. J. Vet. Anat. 

21 (2): 39-42.

•

Sission S and Grossman J D (1974). The anatomy of the domestic animals

fifth edition, pp 629-41, 718-19 W B Saunders company Philadelphia.

•

Singh O. Roy K.S. Sethi R.S and Kumar A. (2012) Development of large

intestine of buffalo. 

Indian journal of animal sciences

 82(10):83.

Trautmann,A. and Fiebiger. J. (1957).Fundamentals of histology of domestic

animals. Translated and revised by hable, R.E. And Biberstein,E.L. Comstock

Publishing Associates, Ithaca, New York.

•

Ajay, P. and G. Chandra (2000) “Gross anatomical studies on intestine of

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12 (1): 23-26.