Abnormal Intestinal Anatomy in Late-stage Human Fetuses: Three Case Series.

OBJECTIVE: We reported three cases of fetuses with abnormal intestinal anatomy found during our recent study of the transverse mesocolon using 20 late-stage fetuses. CASES: The first case (CRL: 328 mm) appeared to have a duodenum and transverse colon trapped in Winslow's foramen (foramen epiploicum) and the duodenum superior portion elongated rightward. The second case (CRL: 264 mm) had a transverse colon inserted deeply into a space between the right kidney and duodenum. The third case (CRL: 276 mm) had a descending colon that ran inferiorly through a deep space between the left kidney and duodenum. Each case had a greater omentum that was shifted leftward, but this is usual. These 3 abnormalities were not evident in the anterior view during dissection of the liver, stomach, jejunum, and ileum. With underdeveloped pancreatic ducts due to unknown reason other than the internal hernia, the first case seemed to be fatal after birth. However, the second and third cases could have recovered after birth because there was no evidence of definite malrotation and because of loose attachments of the intestines to surrounding structures. CONCLUSIONS: The intestinal morphologies described here could cause some sort of symptoms, such as abdominal pain, whose cause might be difficult to determine.

Anatomy of the Transverse Mesocolon Based on Embryology for Laparoscopic Complete Mesocolic Excision of Right-Sided Colon Cancer.

BACKGROUND: To treat colon cancer via complete mesocolic excision (CME) with central vascular ligation (CVL), dissection along the embryologic fusion planes is required. However, this surgery is difficult, especially for right-sided colon cancer, because the anatomy and embryology of the transverse mesocolon are not familiar to gastrointestinal surgeons. METHODS: In this video article, the anatomic details of the transverse mesocolon based on embryology are illustrated with a focus on the venous anatomy. Dissection of the transverse mesocolon along the embryologic planes using a cranial approach during laparoscopic right hemicolectomy also is presented. RESULTS: During the development of the primitive gastrointestinal tract, the transverse mesocolon locates between the terminal portion of the midgut and the beginning of the hindgut. After 270° counterclockwise rotation of the primary intestinal loop, the transverse mesocolon fuses with the frontal surface of the duodenum and pancreas. Simultaneously, the greater omentum hangs down from the greater curvature of the stomach in front of the transverse colon and fuses with the transverse mesocolon. Moreover, the drainage vein of the right colon sometimes joins the right gastroepiploic vein, and the gastrocolic trunk is formed. Anatomic complexity of the transverse mesocolon is caused by rotation and fusion of the gastrointestinal tract during embryologic development. CONCLUSIONS: Knowledge concerning these embryologic peculiarities of the transverse mesocolon should be useful in the performance of laparoscopic CME with CVL for right-sided colon cancer.

The development of large intestine during the fetal period.

OBJECTIVE: The aim of this study is to determine the colon types, developmental change of the colon morphology during the fetal period. METHODS: The study was realised on 131 human fetuses (male 69, female 62) ages between 10 and 40 weeks, which have no external pathology and anomalies. The colon types were evaluated in two parts. As the first part, the colon part between the ileal orifice and sigmoid colon was typed. The sigmoid colon was typed as the second part. The macroscopic diameters of parts of the colon and the thicknesses of wall layers of ascending and descending colons were measured under the light microscope. RESULTS: For the proximal part of the colon, there were seven types of colon, and there were five types for the sigmoid colon. For the first part, transverse type colon was a rare type during the fetal period (3%). The oblique type colon was observed mostly in the first and second trimester during the fetal period. Adult type colon was the most common type in the third trimester and full-term groups. The pendulous type colon was observed mostly in the third trimester. The development of the haustra and tenia coli in the first trimester was quite slow, but later the development increased more and more, and during the full-term period, the haustra and tenia coli could be seen clearly. CONCLUSION: The percentage distribution of the colon types between the trimesters was significant. It was observed that the maturation of haustra and tenia coli started from the ascending colon and progressed towards the sigmoid colon. The thickness of the tunica mucosa layer both in the ascending and in descending colon part increased considerably in the middle of the second trimester.