Table Of Content

0–2 weeks EMBRYONIC DISC FERTILIZATION DORSAL VIEW Oropharyngeal membrane Not sensitive usually High rate of lethality Epiblast may occur Hypoblast Primitive streak DORSAL ASPECT OF EMBRYO Oropharyngeal 3–8 weeks membrane Period of greatest sensitivity Prenotochordal cells Primitive Each organ system will node also have a period of Primitive peak sensitivity streak Toes FETAL MEMBRANES 9–38 weeks IN THIRD MONTH Decreasing sensitivity Period of functional maturation RISK OF BIRTH DEFECTS BEING INDUCED k s Ri g n si a n e o ncr uriti I art P 0 3 5 8 38 Embryonic Period Fetal Period WEEKS GESTATION SSaaddlleerr__FFMM..iinndddd ii 88//2255//22001111 1122::5544::2200 PPMM Day 1 Fertilization Day 2 Two-cell stage Day 3 Morula Day 4 Early blastocyst Day 8 Fertilization Day 9 Trophoblast with Day 10-11 Embryo in uterus 10-11 days after ovulation lTaroclapuchuonnbaaaelsetic Enlavregsesde blslood Maturation of follicleOvulation Cluoterpuums Coof rppruesg nluatenucym Implanted embryo Implantation begins Gland Compact layer Cytotro- Spongy Epiblasts Hypoblast phoblast Ysoalck Blaaysearl layer Fibrin coagulum Emxoecmoberlaonmeic Day 15 Laterality Day 16 Gastrulation: Day 17 Epiblast forms Day 18 Trilaminar established Formation of germ layers germ layers embryonic disc Primitive NFGodFa8l Neural node Psritmreiativke Ectoderm Mesoderm Lefty2 tube PITX2 Lefty 1 N(SoHtoHc,h To)rd Primitive Nodal Snail node Endoderm N(FoGdFe8) Psritmreiativke mIensvoadgeinrmat icneglls Notochord Day 22 Neural tube Day 23 Neural tube zippers Day 24-25 Villus formation continues in the placenta closure begins Anterior Neural fold neuropore Syncytiotrophoblast Mesoderm core Villous capillary Pbuelrgiceardial Pbuelrgiceardial Otic placode Somite Cut edge Cytotrophoblast Cut edge of amnion A Primary B Secondary C Tertiary of amnion Posterior villus villus villus neuropore Day 29 Arm and leg buds Day 30 Developing face Day 31 Gut development Day 32 Embryo in chorionic cavity Villi Fprroomntionneanscael Lung bud Ocyutotebrlast Nasal shell placode Foregut Mpraoxmililnaeryn ce Cplhaoterionic Mandibular arch Midgut Chorionic cavity Cloaca Hindgut Decidua capsularis Day 36 Physiological Day 37 Developing face Day 38 Muscle Day 39 Endodermal umbilical hernia development derivatives Omcycoitpoimtaels Parhcahr ymnugsecalels Phpaoruycnhgeesal LMpparretooedmmriaaiinlnl ennenaancssceaaell Eye Cemryviotcoalmes C1 IVIIIII Emyuescles ppMrMrooamamnxdiininlilbeaeunrnylccaeer Nasgorolaocvreimal Thoracicmyotomes T1 I bUlraindadreyr Day 43 Limb cartilages Day 44 Developing face Day 45 Conotruncal and Day 46 and digital rays ventricular septa Decidua basalis Decidua Chorion parietalis frondosum Pubis Aorta Pulmonary valves Tibia Right Chcoarvioitynic Acmanviiotytic artrium Yolk sac Fibula Femur Ilium Eye Troicriufiscpeid cDapescuidlaurais Uctaevriintye Nasolacrimal Tarsal cartilages groove Philtrum Clhaoervieon Interventricular septum SSaaddlleerr__FFMM..iinndddd iiii 88//2255//22001111 1122::5544::2211 PPMM Day 5 Late blastocyst Day 6-7 Events during first week: Uterine Fertilization to implantation epithelium Uterine stroma 30 hours Time of 4 3 days repDlicNaAtion 3 5 6 Tropho- Corpus luteum blast 7 4 days Development Blacsatvoictyyst cells 41/2-5 days Week 1 8 12-24 hours 2 Outer cell mass Emblbarsyto- F1imPbrreiaovulatMoryyo fmolelitcrlieum 51/29-6 days or trophoblast Perimetrium Endometrium Day 12 Fertilization Day 13 Uteroplacental Day 14 Embryonic disc: circulation begins dorsal view Primary villi Bucco- pharyngeal Cut edge membrane Acmanviiotytic of amnion Development Yolk sac Week 2 CChhcpooalarrviitoioteynniicc Psritmreiativke HypoblastEpiblast oWfs yaaoclllk Yolk sac Extraembryonic mesoderm Day 19 CNS induction Day 20 Neurulation: Day 21 Transverse section Neural folds elevate through somite region Cut edge oNf eaumrnailon NoCfe uautm reandl igfooenld Inmteersmoeddeiramte Somite plate Development gNreouorvael Week 3 Somite Body Primitive cavity node Primitive Primitive streak streak Day 26 Pharyngeal arches Day 27 Day 28 Neurulation present Approx. Age No. of complete nAeunrtoeprioorre 1pshtaa arrcynhndeg 2senadl (Da2y0s) Som1-i4tes plLaecnosde Otic placode 21 4-7 22 7-10 Development 23 10-13 Limb Week 4 24 13-17 ridge 25 17-20 26 20-23 27 23-26 28 26-29 Posterior 30 34-35 neuropore Day 33 Umbilical ring Day 34 Optic cup and lens Day 35 Branchial arches placode and clefts Amnion Chorionic cavity Meckel's Yolk sac cartilage Forebrain Consntaelckting Phacrlyenftgeal Development Week 5 Mandibular arch Lens placode Optic cup Hyoid arch Day 40 Auricular hillocks Day 41 Atrial septum Day 42 Digit formation formed Areas of cell death Septum secundum Septum primum Auricular hillocks LA RA Development Week 6 123654 RV LV Interventricular septum Day 47 External genitalia Day 48 Facial prominences Day 49 Digits present, Genital fused eyelids forming tubercle Genital swelling Development Urfeotlhdral LMpparretooedmmriaaiinlnl ennenaancssceaaell Eye Week 7 prMomaxinilleanryce pMroamndinibeunlcaer Nasgorolaocvreimal Anal fold SSaaddlleerr__FFMM..iinndddd iiiiii 88//2255//22001111 1122::5544::2233 PPMM SSaaddlleerr__FFMM..iinndddd iivv 88//2255//22001111 1122::5544::2255 PPMM SSaaddlleerr__FFMM..iinndddd vv 88//2255//22001111 1122::5544::2255 PPMM Acquisitions Editor: Crystal Taylor Product Manager: Stacey Sebring Marketing Manager: Joy Fisher-Williams Designer: Holly Reid McLaughlin Compositor: SPi Global Copyright © 2012 Lippincott Williams & Wilkins, a Wolters Kluwer business. 351 West Camden Street Two Commerce Square Baltimore, MD 21201 2001 Market Street Philadelphia, PA 19103 Printed in China All rights reserved. This book is protected by copyright. No part of this book may be reproduced or transmitted in any form or by any means, including as photocopies or scanned-in or other electronic copies, or utilized by any information storage and retrieval system without written permission from the copyright owner, except for brief quotations embodied in critical articles and reviews. Materials appearing in this book prepared by individuals as part of their offi cial duties as U.S. government employees are not covered by the above-mentioned copyright. To request permission, please contact Lippincott Williams & Wilkins at Two Commerce Square, 2001 Market Street, Philadelphia, PA 19103, via email at [email protected], or via website at lww.com (products and services). Library of Congress Cataloging-in-Publication Data Sadler, T. W. (Thomas W.) Langman’s medical embryology. — 12th ed. / T.W. Sadler. p. ; cm. Medical embryology Includes index. ISBN 978-1-4511-1342-6 1. Embryology, Human—Textbooks. 2. Abnormalities, Human—Textbooks. I. Langman, Jan. Medical embryology. II. Title. III. Title: Medical embryology. [DNLM: 1. Embryology. 2. Congenital Abnormalities. QS 604] QM601.L35 2012 612.6'4—dc23 2011025451 DISCLAIMER Care has been taken to confi rm the accuracy of the information present and to describe generally accepted practices. However, the authors, editors, and publisher are not responsible for errors or omissions or for any consequences from application of the information in this book and make no warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of the publication. Application of this information in a particular situation remains the professional responsibility of the practitioner; the clinical treatments described and recommended may not be considered absolute and universal recommendations. The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with the current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant fl ow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new or infrequently employed drug. Some drugs and medical devices presented in this publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings. It is the responsibility of the health care provider to ascer- tain the FDA status of each drug or device planned for use in their clinical practice. To purchase additional copies of this book, call our customer service department at (800) 638-3030 or fax orders to (301) 223-2320. International customers should call (301) 223-2300. Visit Lippincott Williams & Wilkins on the Internet: http://www.lww.com. Lippincott Williams & Wilkins customer service representatives are available from 8:30 am to 6:00 pm, EST. 9 8 7 6 5 4 3 2 1 SSaaddlleerr__FFMM..iinndddd vvii 88//2255//22001111 1122::5544::2288 PPMM Dedication For each and every child and to Dr. Tom Kwasigroch for his wonderful friendship, excellence in teaching, and dedication to his students. Special thanks: To Drs. David Weaver and Roger Stevenson for all of their help with the clinical material, including providing many of the clinical fi gures. To Dr. Sonja Rasmussen for her help in reviewing all of the clinical correlations and for her expert editorial assistance. SSaaddlleerr__FFMM..iinndddd vviiii 88//2255//22001111 1122::5544::2288 PPMM P R E F A C E Every student will be affected by pregnancy, Genetics: Because of the increasingly important either their mother’s, since what happens in roll of genetics and molecular biology in embryol- the womb does not, necessarily, stay in the ogy and the study of birth defects, basic genetic and womb, or by someone else’s. As health care pro- molecular principles are discussed. The fi rst chapter fessionals you will often encounter women of provides an introduction to molecular pathways and childbearing age who may be pregnant, or you defi nes key terms in genetics and molecular biology. may have children of your own, or maybe it is Then, throughout the text, major signaling path- a friend who is pregnant. In any case, pregnancy ways and genes that regulate embryological devel- and childbirth are relevant to all of us, and unfor- opment are identifi ed and discussed. tunately, these processes often culminate in nega- Extensive Art Program: Nearly 400 illustra- tive outcomes. For example, 50% of all embryos tions are used to enhance understanding of the text, are spontaneously aborted. Further more, prema- including four-color line drawings, scanning elec- turity and birth defects are the leading causes of tron micrographs, and clinical pictures. Additional infant mortality and major contributors to dis- color pictures of clinical cases have been added to abilities. Fortunately, new strategies can improve enhance the clinical correlate sections. pregnancy outcomes, and health care professionals Summary: At the end of each chapter is a sum- have a major role to play in implementing these mary that serves as a concise review of the key points initiatives. However, a basic knowledge of embry- described in detail throughout the chapter. Key terms ology is essential to the success of these strategies, are highlighted and defi ned in these summaries. and with this knowledge, every health care profes- Problems to Solve: Problems related to the sional can play a role in providing healthier babies. key elements of each chapter are provided to To accomplish its goal of providing a basic assist the student in assessing their understanding understanding of embryology and its clinical rel- of the material. Detailed answers are provided in evance, Langman’s Medical Embryology retains its an appendix at the back of the book. unique approach of combining an economy of Glossary: A glossary of key terms is located text with excellent diagrams and clinical images. in the back of the book and has been expanded It stresses the clinical importance of the subject extensively. by providing numerous clinical examples that thePoint Web site: This site for students and result from abnormal embryological events. The instructors provides the full text of the book and following pedagogic features and updates in the its fi gures online; an interactive question bank of 12th edition help facilitate student learning. USMLE board-type questions; and Simbryo ani- Organization of Material: Langman’s Medical mations that demonstrate normal embryologi- Embryology is organized into two parts. The fi rst cal events and the origins of some birth defects. provides an overview of early development from Simbryo offers six vector art animation modules to gametogenesis through the embryonic period. illustrate the complex, three-dimensional aspects Also included in this section are chapters on pla- of embryology. Modules include an overview of cental and fetal development as well as prenatal the normal stages of early embryogenesis, plus diagnosis and birth defects. The second part of development of the head and neck and the geni- the text provides a description of the fundamental tourinary, cardiovascular, and pulmonary systems. processes of embryogenesis for each organ system. Teaching aids for instructors will also be pro- Clinical Correlates: In addition to describ- vided in the form of an image bank and a series of ing normal events, each chapter contains clinical lectures on the major topics in embryology pre- correlates that appear in highlighted boxes. This sented in PowerPoint with accompanying notes. material is designed to demonstrate the clinical I hope you fi nd this edition of Langman’s relevance of embryology and the importance Medical Embryology to be an excellent resource for of understanding key developmental events as a learning embryology and its clinical signifi cance. fi rst step to improving birth outcomes and hav- Together the textbook and online site, thePoint, ing healthier babies. Clinical pictures and case are designed to provide a user-friendly and inno- descriptions are used to provide this information vative approach to understanding the subject. and this material has been increased and updated T.W. Sadler in this edition. Twin Bridges, MT viii SSaaddlleerr__FFMM..iinndddd vviiiiii 88//2255//22001111 1122::5544::2288 PPMM