Larsen's Human Embryology

Citation

Schoenwolf, G. C., Bleyl, S. B., Brauer, P. R., & Francis-West, P. H. (2021). Larsen's Human Embryology (6th ed.). Elsevier.

Chapter Summary

The sixth edition has twenty chapters. The first four follow development week by week from gametes to the four-week embryo; Chapter 5 steps back to the general principles of morphogenesis, Chapter 6 covers the fetal period, and Chapters 7 to 20 take the organ systems one at a time. The publisher says each chapter opens with an overview of its main points and a graphical summary, with key terms in bold, and that the text integrates anatomy and histology with cellular and molecular mechanisms and with congenital anomalies.

Chapter 1: Gametogenesis, Fertilization, and First Week

The starting point of the book: the formation of the gametes, fertilization and the events of the first week of development.

Chapter 2: Second Week: Becoming Bilaminar and Fully Implanting

Development in the second week, when the embryo becomes two-layered and implantation is completed.

Chapter 3: Third Week: Becoming Trilaminar and Establishing Body Axes

The third week, in which the embryo becomes three-layered and the body axes are established.

Chapter 4: Fourth Week: Forming the Embryo

The fourth week, when the embryo itself takes shape. Together with Chapters 1 to 3 it gives the chronological backbone to which later system chapters refer.

Chapter 5: Principles and Mechanisms of Morphogenesis and Dysmorphogenesis

A general chapter on how normal form arises and how abnormal form (dysmorphogenesis) arises, placed after the weekly account and before the organ systems.

Chapter 6: Fetal Development and the Fetus as a Patient

Covers the fetal period and the clinical view of the fetus as a patient.

Chapters 7–8: Development of the Skin and Its Derivatives; Development of the Musculoskeletal System

The first two system chapters deal with the skin and its derivatives and with the musculoskeletal system.

Chapters 9–10: Development of the Central Nervous System; Development of the Peripheral Nervous System

The two nervous-system chapters are split into central and peripheral parts.

Chapter 11: Development of the Respiratory System and Body Cavities

Treats the respiratory system together with the body cavities.

Chapters 12–13: Development of the Heart; Development of the Vasculature

The cardiovascular system is divided into the heart and the vessels.

Chapter 14: Development of the Gastrointestinal Tract

The development of the digestive tract.

Chapters 15–16: Development of the Urinary System; Development of the Reproductive System

The urinary and reproductive systems are given a chapter each.

Chapters 17–20: Development of the Pharyngeal Apparatus and Face; Development of the Ears; Development of the Eyes; Development of the Limbs

The final chapters cover the pharyngeal apparatus and face, the ears, the eyes and the limbs.

Key Concepts

Chapters 1–4: The First Four Weeks

• Bilaminar and trilaminar embryo: the second and third week chapters are organised around the embryo becoming two-layered and then three-layered.
• Body axes: established in the third week.
• Implantation: completed in the second week.

Chapters 5–6: Morphogenesis and the Fetus

• Morphogenesis and dysmorphogenesis: the mechanisms behind normal and abnormal form.
• The fetus as a patient: the fetal period viewed from the clinical side.

Chapters 7–20: Organ Systems

• Organ-system development: skin, musculoskeletal, central and peripheral nervous, respiratory, heart, vasculature, gastrointestinal, urinary, reproductive, pharyngeal apparatus and face, ears, eyes and limbs.
• Clinical and research boxes: the publisher names "Clinical Taster", "Embryology in Practice", "In the Clinic" and "In the Research Lab" sections, which tie development to clinical conditions and to the experiments behind the mechanisms.

Critical Analysis

Strengths

• A clear two-part structure. Chronological chapters first, then one chapter per system, so a reader can follow either the whole embryo through time or a single organ from beginning to end.
• Clinical and experimental material kept visibly separate. Boxed sections mark the clinical applications and the research background, which lets a medical student skip the research boxes while a graduate reader can concentrate on them. Brian R. MacPherson, reviewing the book for Doody's Review Service, wrote that medical students will care little about the "In The Research Lab" boxes but that senior undergraduates and graduate students will find them of interest.
• Learning aids built into each chapter. Chapter overviews, graphical summaries and key terms in bold are described by the publisher, and the enhanced eBook includes narrated animations (50, according to the publisher) and multiple-choice questions. The Doody's review gave the book 4 stars (score 91) and called it a very comprehensive learning tool with many well-done diagrams.
• Both normal and abnormal development. The publisher describes the focus as normal development and congenital anomalies, with the dysmorphogenesis chapter providing the general mechanisms.

Limitations

• Heavy for a first look. It is a full textbook with twenty chapters, so readers who only need the essentials will find it more than they need. The shorter text listed below may serve them better.
• References are selective. The Doody's review notes that each chapter ends with a limited number of suggested readings, which is a starting point rather than a literature survey.
• Scope. The book is about human development; it is not an anatomy atlas or a histology text, so tissue structure and gross anatomy must come from other books.

Where It Fits in the Course

Within this course list, Larsen's is the detailed embryology text. Before We Are Born is a concise, illustrated introduction, derived from the longer textbook The Developing Human, that follows development from fertilisation to birth and explains how birth defects arise. It is the better first read, or a revision text, for anyone who needs the essentials of each stage and system.

The course also lists several histology books. Junqueira's Basic Histology and Wheater's Functional Histology teach normal tissues and organs, and Histology: A Text and Atlas does so with a cell and molecular emphasis; Mills's Histology for Pathologists is a pathologist's reference on normal tissue. Larsen's explains how the tissues and organs described in those books come to exist, so it is useful to read it alongside a histology course, and its system chapters match the organ-by-organ structure of histology texts.

How to Use This Book

The book is aimed at health-related students, including medical students in an embryology or integrated anatomy course, and at graduate students in embryology. Gross anatomy and cell biology are the sensible background; some familiarity with gene regulation and cell signalling helps with the molecular explanations.

A practical plan: read Chapters 1 to 4 first and in order, then Chapter 5, since the weekly chapters provide the chronology that the system chapters build on. After that, read the system chapters in the order your course teaches them. Chapter 20 on the limbs pairs naturally with the musculoskeletal chapter (8). Use the clinical boxes to connect development with congenital anomalies you will meet in paediatrics, and treat the research boxes as optional unless you work in developmental biology. Use the animations and questions with the enhanced eBook for revision.