Transcription
D shape tube with dorsal mesome. Okay, you see here in the border between, in the territory between foregut and midgut, the liver bud emerges from the foregut and enters into the septum transversum. Yeah, a mesodermal septum that is related to the C3, C4, and C5 somites and makes the central tendon of the diaphragm. Have a look here, have a look here.
[Music]
The developing dome grows rapidly, forming a C-shaped loop that projects ventrally and makes a duodenal loop. With rotation of the stomach 90 degrees clockwise, this duodeno goes to the posterior abdominal wall and becomes retroperitoneal. In the development of the peritoneal cavity and peritoneal folds and mesentery, if two layers of peritoneum attached together, these two layers disappear. Okay, is it clear with this rotation of the dome? Dome attached to the posterior abdominal wall, and these two layers attached together and disappear, and the dome becomes intra-retroperitoneal and intraperitoneal organ becomes secondarily retroperitoneal during the fifth and sixth weeks.
The lumen of the duodenum, similar to other parts of the digestive tract, becomes solid. Proliferation of the cells makes it solid and then makes recanalization. This solidation and recanalization make the wall of the duodenum and other parts of the small intestine larger and thicker. Okay, proliferation, solidation, and recanalization make the wall of the small intestine larger and thicker. Okay, and the lumen becomes elongated. Duodenal atresia is not common, but there is duodenal stenosis or duodenal atresia in the duodenum that makes vomiting with bile. Vomiting with bile. This is not projectile, but in pyloric stenosis, there is projectile vomiting. Here it is not projectile, projectile, just it has bile, contains bile, bile.
The liver, gallbladder, and biliary tract arise as a ventral outgrowth. The liver bud or hepatic diverticulum from the distal part of the foregut. Early in the fourth week, the liver diverticulum or hepatic diverticulum or hepatic bud or liver bud extends into the septum transversum, a mass of splanchnic mesoderm there, separating the pericardial and peritoneal cavities. I told all of these. Liver bud rapidly and divides into two parts as it grows between the layers of ventral mesogastrium or mesentery of the dilated portion of the foregut. Here, a part of this liver after enlargement, after the development, attached to the diaphragm and makes the bare area of the liver. Bare area of the liver. You see here, the proliferating endodermal and mesodermal cells form intervening cords, hepatocytes, hepatic cords, and sinusoids. Hepatic sinusoids. And between them, there are there are sinusoids. The fibrous connective tissue and hematopoietic tissue and Kupffer cells, macrophages of the liver. Yeah, or mesoderm of the septum transversum. If I ask you, what is the origin of hepatocytes? You answer me: endoderm of the duodenum and liver bud. Endoderm of the duodenum and liver bud. If I ask you, what's the origin of Kupffer cells in the liver, or connective tissue in the liver, or hematopoietic cells in the liver? You answer me: septum transversum mesenchyme of the transverse septum.
Development of the liver from the fifth to the tenth week makes an enlargement in the ventral mesogastrium and divides the ventral mesogastrium into two parts. A part between the liver and the anterior abdominal wall that is called the falciform ligament, and the inferior border of the falciform ligament contains the umbilical vein that after birth, this umbilical vein becomes ligamentum teres hepatis. And a part between the liver and the lesser curvature of the stomach that is called the lesser omentum. In the inferior free border of the lesser omentum, there are three structures that after the second rotation of the stomach, this free border becomes the right free border of the lesser omentum. It contains the hepatic artery proper, common bile duct, and portal vein.
Hematopoiesis, formation of the various types of blood cells, begins in the liver during the sixth week. One of the most important functions of the liver is hematopoiesis. From the sixth week to the tenth week, by the ninth week, the liver accounts for approximately 10% of the total weight of the fetus, but in adults, there is just 2%. Yeah, I told you in anatomy, the liver is a large organ that makes 2% of the body weight. Yeah, similar to the brain. Bile formation by hepatic cells begins during the twelfth week. It's very important. I will ask you this. This slide, I will ask you. Okay, this is very, very important that you know bile formation occurs at the twelfth week. Twelfth week is which month? Tenth week. Yeah, this is the third month.
Liver cords differentiate from the fetal parenchyma. Liver cells and form the lining of the bile ducts. Hematopoietic cells, Kupffer cells, connective tissue cells are derived from mesoderm of the septum transversum. The small caudal part of the hepatic diverticulum or liver diverticulum or liver bud becomes the gallbladder. Becomes the gallbladder, and the stalk of the diverticulum forms the cystic duct. This is the gallbladder, and here is the cystic duct. Both of them originate from originate from the liver diverticulum, liver bud. Yeah, these are endodermal. Initially, the extra-extrahepatic biliary apparatus is occluded with epithelial cells, epithelial cells, but is later canalized, similar to the duodenum. I told you, yeah. In some cases, in some abnormalities, maybe canalized. Canalization of these biliary ducts will be abnormal and makes some congenital malformations. The stalk of the diverticulum connecting the hepatic and cystic duct to the duodenum becomes the common bile duct. This is the common bile duct. Initially, this duct attached to the ventral aspect of the duodenal loop. Over as the duodenum grows and rotates, the entrance of the common bile duct is carried to the dorsal aspect of the duodenum. At first, this opening is anterior to the duodenum, but after rotation, goes to the dorsal part. The bile entering the duodenum through the common bile duct after the third week gives meconium. Meconium is the intestinal discharge of the fetus. Meconium, green intestinal discharge of the fetus.
I told you the umbilical vein is located in the free border of the falciform ligament and after birth becomes ligamentum teres hepatis. You see here, this is ligamentum teres hepatis. This is the umbilical vein, and after birth becomes ligamentum teres hepatis. Or I said, after development of the liver in the septum transversum and descending of the liver into the abdomen, the liver becomes intraperitoneal, and all parts of the liver are covered by peritoneum except the bare area, except a posterior part of the liver that is attached to the diaphragm and makes the bare area. A part of a part of the ventral mesogastrium that is located between the anterior surface of the liver and the anterior abdominal wall is called the falciform ligament. And in the inferior free border of the falciform ligament, there is the left umbilical vein. After birth, this left umbilical vein becomes ligamentum teres hepatis or round ligament of the liver. Is it clear? Left umbilical vein becomes ligamentum teres hepatis in the free inferior border of the falciform ligament. The left side, the right side. I told you in the circulatory system, there are two umbilical veins, but the right umbilical vein is obliterated and obliterated and disappears, and just the left one is functional. Yeah. In the umbilical cord, there are two arteries and one vein. Two arteries and one vein. Is it clear? Yeah, yeah, yeah, yeah. That left umbilical vein from the inferior border of the falciform ligament goes to the inferior border of the liver and is connected to the inferior vena cava by a venous duct, ductus venosus. Yeah, ductus venosus. And this ductus venosus after birth becomes ligamentum venosum. Ligamentum venosum. Between ligamentum teres and inferior vena cava. Is it clear? Okay. This is the bare area of the liver. Bare area of the liver is a posterior part of the liver that is attached to the diaphragm and it doesn't have peritoneum. Yeah, I told you the liver is a large intraperitoneal organ without without peritoneum. And the posterior surface and the posterior. Yes. And the fundus of the gallbladder is the same. Yeah, yeah, it's the same.
In addition to the liver bud or hepatic diverticulum, two buds that are called dorsal pancreatic and ventral pancreatic buds are located in the ventral mesogastrium and dorsal mesogastrium. Day 26. Yeah, there are two buds. Anterior pancreatic bud in the ventral mesogastrium and posterior pancreatic bud in the dorsal mesogastrium. You see here, after rotation of the stomach and duodenum. Okay. Anterior pancreatic bud and common bile duct go to the right and dorsal to the dorsal pancreatic bud and attach to the dorsal pancreatic bud. You see here, this rotation. Ventral pancreatic bud, ventral pancreatic bud. After this rotation, makes the inferior part of the head of the pancreas, cross, and uncinate process. And the dorsal pancreatic bud makes the superior part of the head, neck, trunk, and tail of the pancreas. You see here, each pancreatic bud has one duct, one tube that opens to the duodenum. Yeah, this is this is the dorsal pancreatic duct and this is the ventral pancreatic duct. Yeah, after this rotation of the ventral pancreatic bud and attachment to the dorsal pancreatic bud, you see here, the main part of the dorsal pancreatic duct attached to the ventral pancreatic duct and makes Wirsung or main pancreatic duct. Wirsung's duct or main pancreatic duct that opens to the papilla major. Major. And this proximal part of the dorsal pancreatic duct becomes Santorini's accessory pancreatic duct. Yeah, that opens into the papilla minor. Two centimeters superior to the major pancreatic papilla. Yeah, this is rotation of the ventral pancreatic bud and attachment to the dorsal pancreatic bud and with rotation of the duodenum, the pancreas, similar to the duodenum, becomes retroperitoneal. Yeah. At first, the dorsal pancreatic bud is located in the dorsal mesoduodenum. Yeah, but after rotation, the pancreas, similar to the duodenum, becomes retroperitoneal. They are at first intraperitoneal, but then become retroperitoneal. This is a secondary retroperitoneal organ. Pancreas is a secondary retroperitoneal organ, not primary. Aorta, inferior vena cava, kidneys, they are primary. But duodenum, pancreas, and ascending colon and descending colon are secondary retroperitoneal organs. You see here, Wirsung's main pancreatic duct and Santorini's accessory pancreatic duct. Here, if you remember, I told you pancreas has two parts. If I ask you, which organ is exocrine and endocrine together? You answer me: pancreas. Pancreas. If I ask you, which cell has endocrine and exocrine function? Yes, acini. Okay, okay, very good. Very good. Or pancreatic acini are from endo- from pancreatic buds. And between them, there are Langerhans islets. Professor Al is the most famous and very, very intelligent subspecialist in the digestive tract and digestive system. Sorry, Professor Adam. It's very hard for me. I very difficult for me. It's very difficult when you talk about medicine and structures of the body in this class because Professor I and Professor Al and Professor Shafy are very intelligent about medicine and medical teaching and medical education. Sorry. No, just now mention that like anatomy in the basic science is very important in the clinic because he's a gastroenterologist and he every day visits patients of like problems in liver, problems in pancreas. And just now he mentioned that after you go to the hospital, you will understand that this anatomy and like details, each organ is like the location of very important. Please just pay attention. Thank you. Thank you so much.
Okay, similar to the liver, connective tissue of the of the pancreas is formed by splanchnic mesoderm. Splanchnic mesoderm or mesoderm. Insulin secretion begins during the early fetal period at 10 weeks, and glucagon, somatostatin, and beta and insulin are secreted at after fifth weeks. Ventral pancreatic bud has two parts. Listen carefully. Ventral pancreatic bud has two parts, right and left part. Okay, these two parts attach together and rotate and attach to the dorsal pancreatic bud. This is the normal condition. If these two parts separate and turn around the duodenum and then attach to the dorsal pancreatic bud, in this condition, there is an abnormality that is called annular pancreas. Annular pancreas. You see here that makes stenosis of the duodenum. Stenosis of the duodenum. Yeah, this is annular pancreas, one of the congenital malformations of the duodenum and pancreas. Cause of this, many factors such as genetic factors. Genetic factors. If Dr. Al, do you have any com- I think genetic factors and another environmental factors. There are, you know that in congenital malformations, there are genetic factors and environmental factors and other environmental factors such as infections, such as parasites, and toxins make some congenital malformations. Need some surgery, and we need surgery. Yeah, yeah. In the first stage, you should use surgery for removing for removing this part. Remove. Yeah, for removing this part.
If you remember, I told you the midgut begins at the level of the liver. The diverticulum or liver bud. Yeah, and the end of the midgut in the adults is right 2/3 and left 1/3 of the transverse colon. Yeah, at first, the midgut has a connection with the yolk sac by the vitelline duct. I told you at first, at the first of this session, at the beginning of this session, I told you there is a connection between midgut and vitelline duct. Yeah, or vitelline stalk. Here, midgut makes a loop. Makes a loop, and the superior mesenteric artery is located in the dorsal mesentery as the axis of this loop. Okay, this is the superior mesenteric artery. This is the celiac artery. Celiac trunk. And this is the superior mesenteric artery as the axis of this loop. There are two, there are two rotations in the midgut around the axis of the midgut, around the superior mesenteric artery. At first, you see here, here is the ileum, here is the ileum, and this part is the beginning part of the large intestine here, and here is another parts of the large intestine, colon. Yeah, at first, there is a 90-degree rotation. 90-degree rotation of this loop around the superior mesenteric artery. This rotation is clockwise or counterclockwise? Which one? Similar to the stomach, is it clockwise or no? Counterclockwise. Which one? Counterclockwise. Yeah, around the superior mesenteric artery. At first, 90-degree rotation. You see here, I told this. Yeah, yeah. You see here, counterclockwise. You see here, this is the superior limb, upper limb, and here is the lower limb. Upper limbs make the jejunum, ileum, cecum, and appendix. And the lower limb makes the ascending colon and transverse colon, right 2/3 of the transverse colon. First rotation is 90 degrees. Upper limb goes to the right side. Have a look here. Upper limb goes to the right side. Okay, and goes to the right side. And in the second counterclockwise rotation, that it is 180 degrees, this upper limb goes to the left side, and the ileum goes to the left side. After this rotation, and the ileum enters into the abdominal cavity. At first, at the end, this part, this inferior part goes to the abdominal cavity at the sixth week. This formation and growth of the midgut makes physiological herniation of the midgut. This midgut goes to the umbilical cord and makes physiological herniation, umbilical hernia. At the tenth week, after the second rotation of the stomach, the midgut returns to the abdominal cavity. Based on this, we tell physiological umbilical hernia. Is there? Is there pathological umbilical hernia? Yes, where? Around the umbilicus. Yeah. In the adults, after birth, maybe small intestine goes to the umbilical sac, umbilical hernia, and makes hernial sac and makes pathological umbilical hernia. But in this condition, this is physiological umbilical hernia. Rotation of the stomach and rotation of the stomach and duodenum are in the same time together. But rotation of the rotation of the midgut begins at the sixth week, after rotation of the stomach and duodenum, at the sixth week, and ends at the tenth week. Umbilical herniation begins at the sixth week with the first 90-degree rotation of the midgut, and then the second one at the tenth week. You see here, during the tenth week, the intestine returns to the abdomen. This is the reduction of the midgut hernia. You see here, at first, the cecum and ileum go to the go to the abdominal cavity, and at the end, the colon enters into into the abdomen. Yeah. At first, the cecum is located under the right lobe of the liver, and there isn't ascending colon. Okay, there isn't ascending colon. But with descending of the cecum from near the near to the liver to the right iliac fossa, ascending colon developed. Ascending colon developed here. Okay, in some cases, maybe you see cecum under the right lobe of the liver in adults. It's possible because descending of the cecum not. Are you see here, this counterclockwise 270-degree rotation of the midgut makes the duodenum posterior to the transverse colon. If this rotation is clockwise, 90 degrees clockwise. Yeah, this is an abnormality, congenital malformation. Duodenum goes anterior to the transverse colon. Yeah, this clockwise rotation makes congenital abnormality. Second bud is formed at the sixth week and then descends and makes ascending colon. And the end part of the second makes appendix vermiform, becomes very small and becomes appendix vermiform that you see here. I told this. Okay, after these rotations. Thank you so much. Thank you for answering good for my questions. Smells very good. Very, very good. Thank you. Thank you. You say yes, yes. He says we we are good students. And you don't say yes. I don't know. It's up to you. It's good day today. Students, we are students. He says, yeah, I know. I know. From. Thank you. Okay.
After returning the midgut into the abdomen, some parts attached to the posterior abdominal wall and become retroperitoneal, such as ascending colon and descending colon. And some parts, such as transverse colon and sigmoid colon, become intraperitoneal. Yeah, become intraperitoneal with mesentery. I told you when two layers of peritoneum attached together in the embryonic period, these two layers disappear. I don't know why. You should ask Allah. You should ask God. Why? I don't know. I told very, very good thinking about creation. The human, human creation is a very, very regular and. Nasam. No, nasam. Yeah, it has a very interesting system in the creation of all parts of the human body. In 2 to 4% of people, a small portion of the vitelline duct between the ileum, between the ileum and the vitelline yolk sac, a remnant of the vitelline duct remains and makes the ileal diverticulum or Meckel's diverticulum. In the normal condition, the vitelline duct should disappear. The vitelline duct should disappear completely. If a part of the vitelline duct remains in the ileum, makes the ileal diverticulum. In 2 to 4% of the people, you see Meckel's diverticulum or ileal diverticulum. About 40 to 60, in some books written 80 cm from the ileocecal valve, there is a diverticulum that is called ileal diverticulum or Meckel's diverticulum. You see here, this is Meckel's diverticulum. Here, in some cases, maybe this vitelline duct becomes fibrous, becomes fibrous tissue that makes volvulus of the small intestine around this. In some cases, maybe this proximal part of the vitelline duct disappears and becomes fibrous, and the distal part becomes umbilical sinus. Umbilical sinus. In some cases, there is an open vitelline duct, open vitelline duct that is called umbilical fistula. Thank you. Yes. Umbilical. Okay. And there are vitelline cysts. In some cases, this is multiple vitelline cysts. And vitelline fistula is related to the disappearing of the vitelline duct. Is it clear? You see here, Meckel's diverticulum or ileal diverticulum. Here is ileal diverticulum with fibrous cord. And this is fistula vitelline fistula. Here is vitelline cyst. And here is the volvulus of the diverticulum. And this is fibrous band.
Another congenital malformation in the midgut is omphalocele. If you remember, I told you at the sixth week. Yeah, sixth week, midgut has a counterclockwise rotation of 90 degrees and goes to the umbilical cord and makes umbilical hernia. This is physiological umbilical hernia. And in the tenth week, after 180 degrees counterclockwise rotation of the midgut. Okay, this midgut returns to the abdomen, the abdominal cavity. Yeah, I told you, if the first stage, making umbilical hernia occurs, and the second stage doesn't occur, the umbilical cord contains the jejunum and ileum and all parts of the midgut. This abnormality is called omphalocele. You can treat this case or you can treat this case or not. Yeah, yeah, with surgery. With surgery. But it's very, very difficult. You have in Iraq, the best one of the pediatric surgeons, pediatric surgeon Dr. Sultan in the Naf. It's very good. Yeah, Dr. Sultan. Do you know who is? Okay. In the Naf. Do you know? Yeah, it's a very, very good surgeon. The best. What you have? You have very good pediatric surgeons in Iraq. I know. But this is a very difficult. [Music] Surgery. Please, please be quiet. Be quiet. This is outside of the body in the umbilical cord. You should return this to the abdominal [Music] cavity. What? Very good question. It's a very good question. Omphalocele is a congenital malformation that the midgut goes outside in the umbilical cord and doesn't return to the abdominal cavity. If if this midgut loops goes outside and enters inside of the abdominal cavity, and after this, some parts of midgut goes to the umbilical cord, this is pathological umbilical hernia. This is umbilical hernia. This is not omphalocele. Omphalocele means going out and doesn't return to the abdominal cavity. Okay. If return to the abdominal cavity and then goes out, this is umbilical hernia. Good question. Thank you. Read this. Read this. What's the reason of this duodenum goes anterior to the transverse colon? Why instead of 270 degrees counterclockwise rotation of the midgut, there is 90 degrees clockwise rotation? In this condition, the upper limb goes to the left, and the inferior part or lower limb goes to the right. But there is a congenital malformation that the duodenum goes anterior to the transverse colon, and it's not retroperitoneal location. It hasn't. It doesn't have retroperitoneal location. It's very [Music] important. Do you need rest? Yes or no? I have a I have a suggestion for you. Continue. Yeah, I have a suggestion for you. Hindgut is very easy and small, very small. Okay, if you agree, we continue this part and then we finish the class. It's better, I think. Do you agree? Okay. Thank you. Your class today is very good. Thank you. [Laughter] Thank you. Okay.
I don't know. It's related to you. You up to you. Good, good. Where is the territory border between midgut and hindgut? Right 2/3, right 2/3, and left 1/3 of the transverse colon. Yeah. At the end of the hindgut, at the end of the hindgut, there is a dilated and extended. What happened? At the end of the hindgut, there is an extended part that is called cloaca or cloaca. You see cloaca? Yeah, you see where? Hand. Hand. Do you know what's the hand? What's the meaning of shish? What's the meaning of shish? No, no. Yeah, yeah, yeah, yeah, yeah, yeah. Chicken. In the shish. Chicken is chicken is small hand and big hand. Do you know what hand? What's a hand? Chicken. Where is Dr. Abdullah? Where [Music] is? Where is Dr. Zahra? Chicken. Mother of. Mother of the chicken. What's the name of mother of the chicken? I will ask. I will ask for we as possible. Just [Music].
Is it clear? No. Listen. Be quiet. Be quiet. The end of the hindgut, similar to the end part of the digestive system of the judge. The judge. Okay, there is an extended part that is called cloaca. Cloaca. At the end of the cloaca, the endoderm of the cloaca attaches to the ectoderm and makes the cloacal membrane. Cloacal membrane. Is it clear? Cloacal membrane is here. One mesodermal septum, one mesodermal septum that is called urorectal septum. The endoderm and divides the cloaca into two parts. Okay, this septum that is called urorectal septum descends and attaches to the cloacal membrane and divides the cloaca into two parts. Anterior part is called urogenital sinus, that anteriorly is attached to the urogenital sinus, and posterior part is called anorectal canal. Posterior part is called anorectal canal. And anterior part of the cloaca is called urogenital sinus. Is it clear? Yeah. Urogenital sinus makes the urinary bladder and urethra. And anorectal canal makes the rectum and anal canal. Cloaca is an endoderm-lined cavity covered at its ventral boundary by the surface ectoderm. Surface ectoderm. This area that endoderm of the cloaca attaches to the ectoderm of the body makes the cloacal membrane. Here is the cloacal membrane. Here is the cloaca and urorectal septum. Okay, divides the cloaca into two parts. Anterior or genital and posterior anoral parts. At the eighth week, at the eighth week, the urorectal septum descends and attaches to the cloacal membrane and makes the perineal body. Yeah, here the perineal body. Is it clear? At the sixth week, the urorectal septum descends, and at the eighth week, attaches to the cloacal membrane and divides the cloaca into the urogenital sinus and anorectal canal. You see here, this is the urorectal septum that divides the cloaca into urogenital sinus and anorectal canal. You see here, and makes the perineal body here. Urogenital sinus develops into the urinary bladder and urethra. And the anorectal canal makes the inferior part of the rectum and the upper 2/3 of the anal canal. If you remember, I told you the upper 2/3 of the anal canal has endodermal origin, and the lower 1/3 has ectodermal origin. The epithelium of these two parts are different. On the upper 2/3, this is simple columnar. Simple columnar. And in the lower 1/3, there is stratified squamous epithelium. Yeah. Between the two parts, there is the pectinate line. If you remember, on the upper 2/3, there are anal columns, and between them, anal sinuses, and inferior to the anal columns, there is the pectinate line. Yeah. You imagine this is the posterior part of the cloaca that is called the anorectal canal. This is endodermal. This is endodermal. And this is ectodermal. After reaching the urorectal septum into the cloacal membrane, cloacal membrane makes here makes the perineal body. Yeah, this area is called perineal body. And divides into urogenital septum and anal membrane. This is this is anal anal membrane. Okay, invagination of this area produces makes the anal. You imagine this is the endodermal part, part, and this is the ectodermal part, and this is the anal pit. Okay. Anal membrane closed these two parts. And there isn't any entrance or passage between them. After removing this, this anal membrane disappears, and the anal canal opens to the outside. Is it clear? Yeah. Upper 2/3 has endodermal origin from the cloaca, and lower 1/3 has ectodermal origin from the anal pit. Yeah. The ectoderm makes stratified squamous epithelium, similar to the skin, and the endoderm makes simple columnar epithelium. Is it clear? Yes. This part is called the pectinate line. Yeah, pectinate line. Inferior to the pectinate line, there is a transition zone. Thank you. There is a transition zone with non-keratinized stratified squamous epithelium. Between the transition zone and the keratinized stratified squamous epithelium, there is a white line of Hilton. Hilton's white line. Here is the anal pit, and this is the anal canal with upper 2/3 endodermal origin and lower 1/3 ectodermal origin. You see here. Okay, here is the pectinate line, and this area is the transition zone, and this area is the white line of Hilton. Yeah, this transition zone is covered by is lined by non-keratinized stratified epithelium. Yeah, I will ask you, which part of the anal canal is lined by non-keratinized stratified epithelium? I will ask you, transition zone. I will ask you, I tell you now. Okay. It's not important. Do you understand? It's very important. I will ask you. Superior 2/3 of the anal canal is formed by hindgut, and blood supply of the hindgut is from the inferior mesenteric artery. Inferior mesenteric artery, and the superior rectal artery is the end branch of the inferior mesenteric artery. Yeah, because the origin of the anal pit and inferior 1/3 of the anal canal is from ectoderm. This part is supplied by inferior rectal arteries, that these arteries are branches of internal pudendal arteries, and internal pudendal arteries related to the internal branches of the internal iliac arteries. I told you megacolon or Hirschsprung's disease is intestinal obstruction. In megacolon, results from impaired innervation and the loss of smooth muscle tone. Tone of the muscle. All muscles in your body, all muscles have one hemic contraction. Your muscles have um, how can I tell you? Proprioception. Yeah, yeah. It's related to the proprioception. Yeah, yeah. In the nervous system, we will talk about proprioception. We have three, we have three types of senses. We have three types of sensory impulses conveying. Exteroception. Exceptive means from outside of the body. How are you? Are you? When I ask him, how are you? He hears my sound. He sees my hand. Yeah. Okay. If I come here and I ask, how are you, Ahmed? Ahmed, yes. Yeah. How are you, Ahmed? By touching him. Yeah. This is exteroception. You see, you hear, you touch. This is exteroception. Another type of sensation is interoception. Okay. Internal organs. You are hungry. Yeah. Now you're hungry. Yeah. If you don't have breakfast, you don't eat breakfast. You are hungry now. Yeah. This is interoception. Some of you tell me, what's the meaning of this? I will go to WC. He knows he needs urination. Yeah. This is interoception. If I tell you, close your eyes. Close your eyes and tell me, what's the position of your right elbow? Your left knee? Can you tell me? Yes. Yes. Okay. Without touching, without seeing, without vision, you understand what's the location and position of your body. This is proprioception. Yeah. There are three types of sensations: exteroception, interoception, and proprioception. Okay. [Music] Yeah. Okay. In megacolon, the developmental explanation is the failure of the neural crest cells to migrate into the colon to form the motor ganglia of the enteric plexus. There isn't motor innervation or the [Music] colon. I will tell next session, next semester, Inshallah. You know. Okay. Okay. Very good. Very good. The vagus nerve and spinal pelvic splanchnic nerves cannot synapse within the plexus to effect contraction of the colon and feces accumulates. This is Hirschsprung's disease or megacolon. This is a summary of all things I told you about embryology of the digestive system. Embryology of the digestive system, as Dr. Al told, as Dr. Al mentioned, is very, very important and difficult. Okay. The endoderm of the primordial gut gives rise to the epithelial lining of the digestive tract, except for the cranial and caudal parts, which are derived from ectoderm, stomodeum, and cloacal membrane. The muscular and connective tissue components of the digestive tract are derived from splanchnic mesoderm surrounding the primitive gut or primordial gut. The foregut gives rise to the pharynx, lower respiratory system, esophagus, stomach, proximal part of the duodenum, pancreas, liver, and biliary tracts. Because the trachea and esophagus have a common origin from the foregut, incomplete partitioning by the tracheoesophageal septum results in stenosis or atresia that I told about this with or without fistulas between them. Hepatic diverticulum or diverticulum or liver bud. The primordium of the liver, gallbladder, and biliary tracts is an outgrowth of the endodermal epithelial lining of the foregut. Epithelial liver cords develop from the hepatic diverticulum and grow into the septum transversum. Connective tissue, Kupffer cells, and hematopoietic cells are from mesenchyme of the septum transversum. Between the layers of the ventral mesentery derived from the septum transversum, primordial cells differentiate into hepatic tissue and lining of the ducts of the biliary system. The pancreas develops from pancreatic buds, ventral and dorsal pancreatic buds, that they are endodermal. When the duodenum rotates to the right, the ventral pancreatic bud moves dorsal and fuses with the dorsal pancreatic bud. The ventral pancreatic bud forms the most part of the head and of the pancreas and uncinate process. The dorsal pancreatic bud forms the remainder remainder of the pancreas. I told the midgut gives rise to the duodenum, inferior part of the duodenum, jejunum, ileum, cecum, appendix, ascending colon, and right two-thirds, right 2/3 of the transverse colon. Midgut forms a U-shaped umbilical loop of intestine that herniates into the umbilical cord during the sixth week, because there is the room of the abdomen is small. While in the umbilical cord, the midgut loop rotates counterclockwise 90 degrees. During the tenth week, the intestine returns to the abdomen, rotating further 180 degrees. And the hindgut gives rise to the left 1/3 of the transverse colon, descending colon, sigmoid colon, rectum, and superior part of the superior 2/3 of the anal canal. The inferior part of the anal canal develops from the anal pit. The caudal part of the hindgut divides the cloaca into the urogenital sinus and rectum. What's the problem? Urogenital sinus gives rise to the urinary bladder and urethra, and rectum and superior part of the anal canal are separated from the exterior by the epithelial plug. This mass of epithelial cells breaks down by the end of the eighth week. Most anal defects result from the abnormal partitioning of the cloaca. This is persistent cloaca. This is very important. Persistent cloaca. You see here, urinary bladder, urethra, and vagina, and anus come to one area, similar to the judge. Similar to hand. This is anal stenosis. Anal pit. Anal pit. Have a look here. What's the problem? There is anal pit stenosis because canalization of the anal pit is not complete. Is anal stenosis? Persistent anal pit. There isn't an opening in the anal canal, and here is the anal pit. And anoperineal fistula. Opening of the anal canal into the perineum instead of the anus. There is some fistula that you see here. And here is rectal atresia and anal canal atresia. Okay. Thank you. Inshallah, at 1 o'clock, we have a practical class. Which class? Yeah, yeah.