A seminar presentation on the embryology of the hindgut

A seminar presentation on the embryology of the hindgut

1. NAME: Ebere Uchenna Emmanuel REG. NO.: 2017/MD/6106 DEPT.: Anatomy COURSE CODE: ANA 441 SUPERVISOR: Dr. Ezemagu EMBRYOLOGY OF THE HINDGUT A Seminar presentation by:

2. OUTLINE 01 02 03 04 05 INTRODUCTION DERIVATIVES OF THE HINDGUT DEVELOPMENT OF THE HINDGUT DEVELOPMENT OF THE HINDGUT CONT’D THE CLOACA 06 THE CLOACA CONT’D 07 08 THE CLOACA CONT’D THE ANAL CANAL 09 CLINICAL CORRELATES 10 CONCLUSION 11 REFERENCES

3. The embryonic endoderm is the source of the epithelial lining of the GI tract and its associated glands and organs. In the 3 rd & 4 th weeks, the ectoderm folds cranially and laterally to form: T he neural plate, then the neural tube in a process called neurulation. Almost simultaneously, the endoderm folds caudally forming the gut tube . 01| INTRODUCTION © Sadler T. W. (2018). Medical Embryology Image showing direction of fold of the Embryo (transverse section)

4. 02| DERIVATIVES OF THE HINDGUT © 2015 TeachMeAnatomy. Image showing the derivatives of the hindgut The left 1/3 rd of the transverse colon; The descending colon; The sigmoid colon; The rectum ; The superior part of the anal canal These developed from the hindgut .

5. The junction between the segment of the TC derived from the midgut and that originating from the hindgut is indicated by change in blood supply from branch of SMA to a branch of IMA . All hindgut derivatives are supplied by the inf. mesenteric artery (artery of the hindgut ). 03| DEVELOPMENT OF THE HINDGUT © 2014 WebMD, LLC. All rights reserved Image showing blood supply to the hindgut

6. The descending colon becomes retroperitoneal as its mesentery fuses with the peritoneum on the left post. a bd. wall. The mesentery of the sigmoid colon is retained . (Moore et al. 2018). 04| DEVELOPMENT OF THE HINDGUT CONT’D © Keith Moore. (2015). The Developing Human Image showing that the descending colon is retroperitoneal

7. The cloaca is the dilatation of the terminal hindgut closed by the cloacal membrane . Terminal portion of the hindgut enters the post. region of the cloaca The allantois enters the ant. region of the cloaca. It receives: The allantois vertically 2 mesonephric ducts on each sides 05| THE CLOACA © Larry C (2013). Netter’s Atlas of Embryology Image showing the hindgut

8. By the 7 th week, urorectal septum fuses with the cloacal membrane, separating the allantois from the hindgut – dividing the cloaca into 2: 1. A dorsal ( narrow ) anorectal canal 2. A ventral (b road) urogenital sinus 06| THE CLOACA CONT’D © Larry C (2013). Netter’s Atlas of Embryology Image showing the hindgut

9. D orsal anorectal canal gives rise to: 1. The rectum 2. The anal canal ( upper half) Ventral urogenital sinus gives rise to: 1. Urinary bladder 2. Urethra 07| THE CLOACA CONT’D © Larry C (2013). Netter’s Atlas of Embryology Image showing the hindgut

10. 08| THE ANAL CANAL © Larry C (2013). Netter’s Atlas of Embryology Image showing the hindgut At the 7 th week, the cloacal membrane ruptures to create: The anal opening for the hindgut The urogenital sinus opening ventrally. By the 9 th week, the anal membrane breaks down: Continuity between the upper and lower parts of the anal canal.

11. 09| CLINICAL CORRELATES Imperforate anus : R esults from failure of rupture of the anal membrane. (Moore et al. 2018 ) Anal stenosis : The anus here is in the normal position, but the anus and anal canal are narrow. ( Sadler T. W., 2018 ). Rectourethral fistula: Abnormalities in the size of the post. region of the cloaca shifts the entrance of the anus ant. © Larry C (2013). Netter’s Atlas of Embryology Abnormal and a normal anal canal (Imperforate anus) Abnormal N ormal

12. 10| CONCLUSION The endoderm gives rise to the derivatives of the hindgut which is the region of the gut from the left 1/3 rd the transverse colon to the upper part of the anal canal; the distal part of the anal canal originating from the ectoderm. The hindgut enters the post. region and the allantois enters the ant. region of the cloaca. Breakdown of the cloacal membrane provides communication to the exterior for the anus and the urogenital sinus.

13. 11| REFERNCES Kadasne , D. K. (2011). Kadasne’s Textbook of Embryology (1 st Edition). New Delhi, Jaypee Brother’s Medical Publishers. PG 221 Chapter 13 Larry C. (2013). Netter’s Atlas of Human Embryology . PG 171 . Lea & Febiger Moore, K. L., Persaud T. (2018). The Developing Human, Clinically Oriented Embryology (8 th Edition). Philadelphia, Saunders Elsevier. PGS 284 – 290 Chapter 11 Sadler T. W. (2018). Medical Embryology (12 th Edition). Lippincott Williams & Wilkins. PGS 228 – 230 Chapter 15 Singh I., Pal G. P. (2010). Human Embryology (8 th Edition). New Delhi. Jaypee Brothers Medical Publishers. PGS 228 – 230 Chapter 15

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