Gross, histological and developmental Anatomy of intestine in domestic animals - PowerPoint Presentation

1. Gross, histological and developmental Anatomy of intestine in domestic animals

2. TOPICS TO BE DISCUSSED Gross AnatomyHistology Embryology

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4. Gastrointestinal tract Rima oris to anus1.Oral cavity- tongue,teeth,salivary glands,hard palat and soft palat2.Pharynx 3. Esophagus 4.Stomach 5.Intestine 6.Liver7.Pancrease 8.Spleen

5. IntroductionThe 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)

6.   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.

7.  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 

8. Gross Anatomy: RuminantsTopography: 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 metersJejunum- about 38-40 meters (longest segment)Ileum- about: 0.8 metersAverage Diameter: 5-6 cm The jejunum was the longest and widest segment of small intestine.

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10. 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.

11. Bile duct opens in 2nd 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.

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13. 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

14. 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

15. 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 inlet2 orifices- ileocaecal –small, caecocolic- large Caecum is directely continuous infront with colon.it usually near ventral end of last rib.

16. Colon 10 meter in length, 12 cm in diameter which diminishes in course of proximal loop up to 5 cm largest part of Large IntestineFrom 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 partTransverse part Descending part

17. A. Ascending colon :a.Proximal loop: runs Cranially-Caudally -Cranially -Ventrallyb.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 abdomenc. 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.ABCArteryabc

18. Descending

19. 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 4th coccygeal vertebrae)Have 02 sphincter- 1. sphincter ani internus-smooth muscle 2. sphincter ani externus-skeleton muscle

20. Intestine of Horse Small intestine22-24 meter long, (7.5-10 cm) Duodenum- about 1m Jejunum- about 20 mIleum - about 1 mLocation -Lies in Dorsal part of left half of abdomen, coils reach to floor and pelvic cavity. Duodenum Horse shoe shape3 parts- 1. Cranial- shape curve 2.Descending- fixed with right dorsal colon 3.Ascending- fixed with base of caecum-concavity of 2nd curve have hepeto-pancreatic ampulla/ diverticulum duodeni/opening of bile and pancreatic duct (cm from pylorus)S

21. Jejunum and ileum- No distinction between two(Last meter is the ileum) -Numerous coils intermingled with small colonLarge intestineCharacterised by bands and sacculationsCaecumIt is very big comma shaped cul-de-sac situated from right iliac and sub-lumber region to abdominal floor caudal to xyphoid cartilage03 parts- base,body and apexHave both ileocaecal and cecocolic orifice in lesser curvature of base situated 5-7.5 cm apart. In between the two Intervening fold is presentBoth opening also have sphincter ilei and sphincter caeci

22. 04 longitudinal bands (Teniae ceci) and 04 rows of sacculation (Haustra ceci)

23. CaecumRight side

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25. Colon of horse02 partsGreat colon (Ascending part)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 flexuresRight ventral Left ventral Left dorsalRight dorsal

26. Right ventral From the base of caecum (at last rib) up to xyphoid cartilage, than it bends sharply to right side form sternal flexure2. Left ventral- passes caudally up pelvic inlet and bends dorsally to form- pelvic flexure3.Left dorsal- passes dorsally or lateral to left ventral and reach up to diaphragm and bends to form Diaphragmatic flexure4.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.

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28. Small colon- from termination of large colon to rectum.Lies in space between stomach and pelvic inlet, dorsal to left part of great colonMingled with small intestine but easily distinguished by 02 rows of bands and sacculationsAttach to sub lumbar muscle by mesocolon and to termination of duodenum by duodinocolic fold of peritoneumArranged in coils

29. 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 cmRectum: as oxApplied: at pelvic flexure chances of obstruction of dry faecal material /indigestion causes colic

30. intestine- DogDuodenum- Retrograde/1st partfrom pylorus passes caudally and somewhat dorsally to visceral surface of liver,near pelvis turn medially (illiac flexure)and passes cranially.Recurrent/2nd partFrom illiac flexure passes cranially and bends ventrally to join jejunum.Bile duct and smaller pancreatic ducts open- 5-8 cm from pylorusLarger pancreatic duct opens 2.5-5 cm further from bile duct or 7.5-13 cm from pylorus

31. Jejunum-6-8 coils between liver and stomachIleum-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 colonCaecum- cork screw shape bands and sacculation absentCaecum

32. CaecumStomachRectum

33. Colon of dog bands and sacculation absent03 parts 1. Ascending- cranially go up to pylorus2. Transverse – short3.Descending- up to ventral surface of left kidney Rectum of dog anal glands present02 lateral anal sacs present which contains dirty gray, fatty substance and unpleasant odourSkin which lines these pouches contains coils glandsFurther caudally skin contains large sebacious Circumanal glandsRectum almost completely covered by peritoneum

34. Pig Small intestine:Duodenum: cranial,descending and ascendingOpening of bile duct 2.5 cm from pylorus and pancreatic duct- 10 cmCaecum- 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

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36. Colon lies chiefly to left of median plane caudal to stomach 03 parts1. Ascending colon- arrange in 3 close, double spiral coils in relation with floor of abdomen, ventrally runs cranially up to stomach and turns left as2. Transverse colon- which passes caudally as 3. Descending colon- reach to pelvic inlet02 teniae and haustra present in ascending colon

37. Ox Horse Dog Pig

38. Species differentiation: Small intestineOxHorse Dog Pig Size 40 to 42 meter long, (5 cm diameter)22-24 meter long, (7.5-10 cm) 1.8-4.8 m, (2.5 cm)16-21 meter,( 4 cm) Duodenum- 1 mJejunum- 40 mIleum -1 mDuodenum- 1m Jejunum- 20mIleum -1 mDuodenum-0.2-0.6 mJejunum &Ileum- 1.6-4.2 mDuodenum-0.7-0.95 mJejunum &Ileum- 15-20mPosition Right half of abdomen with few coils caudal and ventral to rumen. ventral to large intestine. Duodenum is often highest part of tube in right flank.Dorsal part of left half of abdomen, coils reach to floor and pelvic cavity. Duodenum mainly in right costal regionWhen stomach empty , lies ventrally and caudally (right flank)but forced more caudally when stomach full. Duodenum as cow.Mesenteric part above the colon and to right of cecum. Against dorsal right flank and caudal abdominal floor. Duodenum as cow.

39. Small intestineOxHorse Dog Pig Bile duct and pancreatic duct SeparateCommon , diverticulum duodeni/ Ampulla of vater/ hepatopancreatic ampullaSeparateSeparateIleocolic valve is present.Absent AbsentPresent Absent

40. Large intestineOxHorse Dog Pig Size 10-11 meter long7.5 -8.0 meter long60-75 cm4-4.5 meter CecumLengthDiameter0.8 m 12cm1.25 m 20-25cm12.5 – 15 cm 2.5-4 cm20-30 cm7.5-10cmShape Cylindrical with rounded free extremityComma shaped with 4 longitudinal bands. One extremity rounded(base)and pointed(apex) Cork Screw and coiledCylindrical and sacculated with 3 longitudinal bands. Extremity roundedPosition Extend along flank from near ventral end of last rib to the pelvic inletBase extend from 15th rib to tuber coxae on right of median plane. Longitudinal axis extends ventrally over right flank to xiphoid region.On right midway between flank and median plane, dorsal to umblical regionVertical position in left or right flank, reaching abdominal floor between umblicus and pubis

41. Large intestine- cecum:OxHorse Dog Pig Opening sColon and cecum continuous. Ileum joins obliquely.Ileum and large colon enter at lesser curvature of base. Opening are 5 cm apartIleum and colon continuous and cecum joins obliquely.As cow

42. Large intestine- colon :OxHorse Dog Pig Length-Diameter-10 m 7.5cmLarge colon 3-3.7 m , 3-3.5 Small colon 20-25cm,7.7-10 cm40-50 cm 2.5 cm3.5-4 m5 cmPosition In dorsal abdominal cavity, to right of median plane with small intestines. Coiled part in lower right flankLarge colon: mainly in ventral abdominal cavity as dorsal and ventral coils. Extends from sternum to pelvic brim.Small colon:Dorsal to large colon and mingled with small intestine.Short ascending part lies along right flank, with long descending part on left of median plane extending to pelvic cavityOn each side of median plane, mainly to left caudal to the stomach. Coiled part in ventral part of abdominal cavity, dorsal to umblicus

43. Large intestine- colon and rectum :OxHorse Dog Pig Specific characterTubular, no bands and sacculation. Part is coiled . 3parts Ascending,transv-erse and descending.Rectum:Ampulla recti presentSacculated with longitudinal bands, 1-4 on large colon 1-2 on small colon. Great colon- 4 parts/ 3 flexures No bands,Short and like shepherd’s crook. 3parts :Ascending,transverse and descendingCoiled like ox but colon have 2 bands and 2 sacculationsRectum:Ampulla recti present

44. Ox Horse Dog Pig

45. Attachments :ox Duodenum: Cranial part of duodenum- lesser omentumDescending 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 2/3rd 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.

46. 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.

47. Vessels and NerveSmall 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 arteryDescending part- cranial and caudal pancreatoduodenal arteryAscending part- branch of cranial mesenteric artery from left side and from middle colic arteryJejunum – 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.

48. 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 loopCecal 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 supplyThe 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.

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50. Histology

51. 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

52. Small intestine

53. 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 cellsPaneth cellsEnteroendocrine cellsGoblet cells

54. 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 cell.They present throughout glandular region of gastric mucosa and continuing into small and large intestine.

55. 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.

56. Lamina propriaForm 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.

57. 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

58. 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..

59. Gut- Associated lymphatic Tissue(GALT):Includes: (Trautmann and Fiebiger, 1957)Solitary and Aggregated lymphatic nodules( Peyer’s patches)Intra and interepithelial lymphocytesDiffusely arranged lymphocyte in lamina propriaPlasma cellsMacrophages

60. 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: Band like,16-38 in no., starts 20-50 cm from pylorus and last long one is continued in cecum.

61. 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.

62. Tunica muscularis:Inner circular, outer longitudinalThickest in horseMyenteric plexus between 2 muscle layersTunica serosa: layer of loose connective tissue covered by Mesothelium

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64. Duodenum jejunum ileum

65. 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 smoothLonger less coiled, simple tubular intestinal glands with many goblet cells.Absence of paneth cellsAbsence of plicae circularis but longitudinal folds are presentIncrease number of solitary lymphatic nodules.

66. Cecum : In ruminant, dog and pig- lymphatic nodules numerous around the ileal ostium. In horse and cat concentrated near the apex of cecum.

67. 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 smoothIncrease goblet cellsIn cattle & horse: Rectal wall thicker than colonIn carnivores: outer logitudinal layer of tunica muscularis is thickned.

68. :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 foundAnal 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.

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70. 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 )

71. 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.

72. 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)

73. Intestine is formed from that portion of foregut which is caudal to developing stomach and from entire midgut and hindgutForegut – Mouth, pharynx, esophagus, stomach, liver, pancreas and Descending duodenumMid gut- Ascending duodenum, jejunum, ileum, cecum, ascending colon and transverse colonHind gut- Descending colon and rectum (K.S.Roy 2009, Mcgeady et al 2006, Arey, 1954)

74. 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-

75. Rotation Herniation and coilingRe-entry and placement Completion These changes occurs in 3rd to 4th weak of gestation in ruminants, pig and dog1. Rotation:Midgut loop occupies a position in extra- embryonic coelom. it Rotate clockwise , viewed dorso-ventrally. Cranial mesenteric artery act as axis.Initial rotation 1800 Mcgeady et al (2006) Arey, (1954)

76. 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 intestineMcgeady et al (2006)Arey, (1954)

77. 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 2700. Mcgeady et al (2006) Arey, (1954)

78. CompletionThe 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 carnivoresCoiled ascending colon in ruminantsCone-shaped arrangement in pigEnlarged cecum and dorsal ,ventral components of ascending colon in horse

79. HistogenesisVilli begins to appears at 8th weaks.Intestinal glands arise as tubular outgrowth of epithelium at end of 3rd 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 5th 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 11th weakMeconeum begins to collect in intestine after 3rd months. (Arey, 1954)

80. 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.

81. References Frandson R.D., Lee Wilke W. and Fails A.D.(1986). Anatomy and physiology of Farm Animals. 7th 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. 5th 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. 6th Edition, W.B. Saunders Company.Dellmann & Eurell J A (1996). Textbook of Veterinary Histology. 5th Edition, Willium & Wilkins Publication.Eurell J A & Frappier B L (2006). Textbook of Veterinary Histology. 6th 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.

82. 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 intestineand 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 goat” Ind. J. Vet. Anat.12 (1): 23-26.

83. Thanks

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