Development Integumentary System (skin And Appendages)

FETUS Essential elements of embryology

16th Edition

ABEDUR RAHMAN MBBS (DMC), M Phil (DU) Editorial Assistant Dr. Farzana Iqbal

Published by

Afrazul Haque Bhelejan Thakurgaon On behalf of Fetus Publications First published………. September, 1991. Second Edition………. September, 1993. Third Edition………. February, 1995. Fourth Edition………. September, 995. Fifth Edition……….January, 1997 Sixth Edition………. May, 1998 Seventh Edition……….March, 2000 Eighth Edition……….August, 2000 Ninth Edition………. May, 2002 Tenth Edition………. October, 2003 Eleventh Edition………. April, 2004 Twelfth Edition………. December, 2004 Thirteenth Edition………. February, 2006 Fourteenth Edition……….October, 2006 Fifteenth edition ……….January, 2008 Sixteenth edition ……….November, 2008

© MD. ABEDUR RAHMAN AII rights reserved. No part of this book may be reproduced or transmitted in any form or by any means without the written permission of the author.

Cover Design: Abedur Rahman Price: Taka Three hundred and Twenty (320/-) only. For all kinds of correspondence: DR MD ABEDUR RAHMAN Phone: +88 01819-050041 e-mail: [email protected]

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Dedicated to My father for the uncompromising principle that guided his life.

ACKNOWLEDGEMENTS Integumentary System

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FETUS I remember  Dr. A. Hye Fakir EX-Head of the department of anatomy, BSMMU.  Dr. Habibur Rahman. EX Head of the department of anatomy, SBMC  Dr. Shahid-UlIah EX-Head of the department of anatomy, RPMC  Dr. Kazi Rafiqul Haque Head of the department of anatomy, USTC. Chittogong  Late Dr. S.S. Banik. Ex-Associate Professor of anatomy, SSMC.  Dr. Motahar Hossain. Ex-Head of the department of anatomy, DMC.  Dr. Manjar-e-Shamim. Professor & head of the department of anatomy, BSMMU.  Dr. Shamim Ara Head of the department of anatomy, DMC  Dr. Shafiq Haider Asst prof. of anatomy, CMC. for their good wishes to this publication

 Dr. Nazrul Islam 

Principal, Dinajpur Medical College Dr. Rubaiual Morshed Ex Asst. Professor, Pediatric Surgery, DMCH for their kind efforts in revising this book.

I am also grateful to Alauddin (SOMC) and other students who made constructive criticism to make the book more helpful for the students. I want to acknowledge my students Juthy (K-63, DMC) and Sristi (K-63, DMC) for their whole hearted co-operation in editing this 16th edition of the book; Ilias (K-62, DMC), Juwel (K-63, DMC), Pritom (K-63, DMC), Fauzia (NUB) for their constructive criticism for making necessary correction of in this edition. I am also grateful to the doctors and students of different institutions and medical colleges who made constructive criticism to make the book more helpful for the embryology student.

Forewords Integumentary System

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Excellent one

I have gone through the book and found that the author has been succeeded in presenting the essential elements of embryology in an excellent manner. The elements served here are authentic. I hope that this humble presentation will serve its purposes well. My best wishes go to the author.

Prof. Dr. Md. Nazrul Islam MBBS, M. Phil (DU), MS (Glasgow). MHPED (Australia) Principal, Dinajpur Medical College Ex Vice president, BMA

Really charmed to find the simplicity

I have gone through the book Fetus by Dr. Abedur Rahman with interest & have been really charmed to find the simplicity of its presentation & diagrams which depict the wide subject of embryology into the small space of this handy volume. Student can peep into the memory of the whole aspect of embryology through this book instantaneously and comfortably even at rest or in leisure like the cow which enjoys the taste of food by cutting its jaw while at rest. I wish the promising young author & his book a glorious success in the days to come.

Integumentary System

Dr. Kazi Rafiqul Huq Head, dept. of Anatomy USTC, Chittogong.

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AUTHOR’S SAYINGS “The history of man for nine months preceding his birth would, probably, be far more interesting, and contain Integumentary System

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events of greater moment than all three score and ten years that follow it.” --- Samuel Taylor Coleridge It is now well proved that ‘Fetus’ is the most read embryology book in our country. The last 15 editions of the book have proven that it is unique in its field. In this edition, I have tried my best to make it more useful for the students making necessary changes elsewhere. New to this edition Development of different organs at a glance  Answers of all first professional SAQ  Some new information  Some figures and information are modified. All praises for the Almighty. Thanks to all the anatomy teachers and students – past, present, and future.

November 2008

Rahman

Integumentary System

Dr Md Abedur

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Contents Part-1: Introduction

1. Introduction to embryology 2. Reproduction and Development 3. Some basic concepts in embryology 4. Some historical elements on embryology

1 3 8 12

Part-2: General Embryology

5. Gametogenesis: Conversion of germ cells into male & female 6. 7. 8. 9. 10. 11. 12. 13.

gamete Female reproductive cycles and ovulation Pre-embryonic period – I: Fertilization, cleavage and implantation Pre-embryonic period-II: Formation of germ layers (Gastrulation) Embryonic period: Derivatives of germ layers Fetal period Some facts concerning the fetus Fetal membranes and placenta Congenital malformations Developmental genetics

21 34 68 90 115 123 127 155 159

Part-3: Systemic Embryology

14. Cardiovascular system 15. Digestive system 16. Respiratory system 17. Diaphragm and septum transversum18. Urogenital system 19. Head neck and ear 20. Nervous system 21. Skeletal system 22. muscular system 23. Integumentary system Glossary

165 190 231 237 241 279 304 325 329 332 339

Fetus 2 contents SAQ in Embryology Development of Different organ at a Glance

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Look for the other books by the same author 1. D”P evW †cÖmvi: cÖwZKvi I cÖwZ‡iva 2. Medical Genetics 3. Research methodology 4. How to Write a thesis 5. Essentials of Biostatistics

Sample chapter Integumentary System

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Integumentary System

Questions for written examination (1) Give the developments of skin (2.) Give the development of mammary gland Introduction Skin & all its appendages (nail, hair, sebaceous, sweat & mammary gland) develop from surface ectoderm except dermis & melanocytes. Integumentary System

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FETUS Development of Skin Skin develops as follows— 1. Epidermis with nails and hairs - from surface ectoderm. This is at first single layered. By proliferation it gives rise to typical stratified sq. epithelium 2. Melanocytes-From neural crest 3. Dermis — from underlying mesenchyme which comes from dermatome of the somites.

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Fig.: Derivation of components of the skin.

Viva Q.; How do you explain the supply of nail beds by palmer and plantar nerves? Ans. developmentally nails are thickening of epidermis and are found initially on the palmar and plantar aspects of the palm & sole. It is their gradual migration to the dorsal aspect which explains such nerve supply.

Development of mammary gland (breast) Milk  line

An ectodermal ridge extending from axilla to the groin on each side of the body is called milk line. From a small part of this milk line breast develops through following sequence of events.

1. Thickened masses of epidermal cells project into dermis 2. Branching occurs in it and branches are canalized. Proximal ends of the branches form lactiferous duct and distal end proliferates to form secretory elements.

Figure: A and B sections through the (developing mammary) gland at the third and eight months, respectively. C diagram showing the positions of accessory nipples (broken line indicates position of mammary line).

Developmental Anomalies of Breast

Common anomalies of breast are (a) Amastia (absence of breast). (b) PoIymastia (Multiple breast), (c) Athelia (absence of one or both nipples). (d) Polythelia (Supernumerary nipples) (e) Gynaecomastia (occurrence of female breasts in the male)