This book investigates the foundational principles and techniques of genetic manipulation in early mammalian embryos. Rudolf Jaenisch, a pioneer in the field, draws upon his extensive research to detail the methods and implications of altering the genetic makeup of embryos. The work explores the scientific rationale behind these interventions, the experimental approaches used, and the early understanding of how such modifications could impact development and heredity. It serves as a critical early reference for the nascent field of transgenesis in mammals.

This seminal work is recognized as a foundational text in the field of mammalian transgenesis. It provides an authoritative account of the pioneering research conducted by Rudolf Jaenisch, detailing the experimental methodologies and early insights into genetic manipulation of embryos. The book is essential for understanding the historical development of genetic engineering in developmental biology and its initial scientific and ethical ramifications.