Textbook of Clinical Embryology VS-Prelims.indd i VS-Prelims.indd i 6/21/2012 3:46:17 PM 6/21/2012 3:46:17 PM “This page intentionally left blank" Textbook of Clinical Embryology Vishram Singh, ms Professor & Head, Department of Anatomy, Professor-in-Charge, Medical Education Unit, Additional Senior Superintendent of Examination, Santosh Medical College, Santosh University, Ghaziabad, NCR, Delhi. Examiner in National and International Universities; Member, Academic Council, Santosh University; Member, Editorial Board, Indian Journal of Otology; Vice President, Anatomical Society of India; Medicolegal Advisor, ICPS, India; Consulting Editor, ABI, North Carolina, USA. Formerly at: GSVM Medical College, Kanpur; King George Medical College, Lucknow; Al-Arab Medical University, Benghazi (Libya); All India Institute of Medical Sciences, New Delhi. ELSEVIER A division of Reed Elsevier India Private Limited VS-Prelims.indd iii VS-Prelims.indd iii 6/21/2012 3:46:17 PM 6/21/2012 3:46:17 PM Textbook of Clinical Embryology, 1e Vishram Singh ELSEVIER A division of Reed Elsevier India Private Limited Mosby, Saunders, Churchill Livingstone, Butterworth-Heinemann and Hanley & Belfus are the Health Science imprints of Elsevier. © 2012 Elsevier All rights are reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher. ISBN: 978-81-312-3048-0 Medical knowledge is constantly changing. As new information becomes available, changes in treatment, procedures, equipment and the use of drugs become necessary. The authors, editors, contributors and the publisher have, as far as it is possible, taken care to ensure that the information given in this text is accurate and up-to-date. However, readers are strongly advised to confirm that the information, especially with regard to drug dose/usage, complies with current legislation and standards of practice. Published by Elsevier, a division of Reed Elsevier India Private Limited. Registered Office: 305, Rohit House, 3, Tolstoy Marg, New Delhi 110 001. Corporate Office: 14th Floor, Building No. 10B, DLF Cyber City, Phase-II, Gurgaon 122002, Haryana, India. Senior Commissioning Editor: Shukti Mukherjee Managing Editor: Shabina Nasim Development Editor: Goldy Bhatnagar Copy Editors: Richa Srivastava and Shrayosee Dutta Manager – Publishing Operations: Sunil Kumar Manager – Production: NC Pant Cover Designer: Raman Kumar Typeset by Olympus Premedia Pvt. Ltd. ( formerly Olympus Infotech Pvt. Ltd.), Chennai, India. www.olympus.co.in Printed and bound at Ajanta Offset, New Delhi. VS-Prelims.indd iv VS-Prelims.indd iv 6/21/2012 3:46:18 PM 6/21/2012 3:46:18 PM Dedicated to the Sacred Memory of My Parents VS-Prelims.indd v VS-Prelims.indd v 6/21/2012 3:46:18 PM 6/21/2012 3:46:18 PM “This page intentionally left blank" Textbook of Clinical Embryology has been carefully planned for the first year medical and dental students. It follows the revised anatomy curriculum of the Medical Council of India. Following the current trends of clinically oriented study of Anatomy, I have adopted a parallel approach of imparting basic embryological knowledge to students and simultaneously providing them its applied aspects. To help students score high in examinations the text is written in simple language. It is arranged in easily under- standable small sections. While embryological details of little clinical relevance, phylogenetic discussions, and comparative analogies have been either omitted or described in brief, all clinically important topics are described in detail. Because of increasingly significant role of molecular biology and genetics in embryology and study of birth defects, the basic molecular and genetic principles are discussed throughout the text. In addition, a separate chapter on medical genetics has been added. The tables and flowcharts given in the book summarize important and complex information into digestible knowledge capsules. Multiple choice questions have been given chapter-by-chapter at the end of the book to test the level of understanding and memory recall of the students. The numerous simple four-color illustrations and clinical photographs further assist in fast comprehension and retention of complicated information. All the illustrations are drawn by the author himself to ensure accuracy. Throughout the preparation of this book one thing I have kept in mind is that thorough knowledge of embryology is required by Clinicians, especially Gynecologists, Pediatricians, and Pediatric Surgeons for physical examination, prenatal diagnostic tests, and surgical procedures. Therefore, embryological events relevant to prenatal diagnostic and surgical procedures are clinically correlated throughout the text. Further, patient-oriented problems and their embryological and genetic basis are presented at the end of each chapter for problem-based learning so that the students could use their embryological knowledge in clinical situations. Moreover, keeping in mind the relevance of embryological knowledge in day-to-day clinical practice, a separate chapter on developmental events during the entire period of gestation and their application in clinical practice is given at the end of the book. I pay my heartfelt tribute to all the authors of various embryology books, especially Developing Human: Clinically Oriented Embryology, 8th edition by Keith L Moore and TVN Persaud, which I have consulted during the preparation of this book. From Developing Human and few other books, some photographs have been used in this book after obtaining due permission from concerned authorities (please refer to page 331 for Figure Credits). As a teacher, I have tried my best to make the book easy to understand and interesting to read. For further improve- ment of this book, I would greatly welcome comments and suggestions from the readers. All these comments and suggestions can be e-mailed at