A little picture is worth a million words. Chinese proverb Prenatal
human development is an extremely complicated process related to
genetics, biochemistry, anatomy, and physiology. There are no
developmental changes, either chemical or morphologic, without
simultaneous changes in molecular organization. The astonishing buildup
ofbiostructures always precedes their proper function. The development
of an embryo is genetically coded and is based on interactions related
to the selective switching on and off of genes. Interactions are
cell-to-cell mediated, mediated by extracellular fluids, or mediated by
special pathways. Every substance involved in developmental is to be
recognized by its target. interactions, before triggering a metabolic or
a morphogenic event, Complex physical and immunologic recognitions are
involved in the process of differentiation. Small pieces of evidence are
collected to create a mosaic picture elucidating the development. This
picture is fascinating and represents the biggest biological puzzle: the
puzzle of development. There is no doubt that analysis of human prenatal
development is a basis for understanding normal and pathologic
relationships between structure and function. Today, there are
approximately 2000 different inborn congenital anomalies and syndromes.
This book attempts to present a complete realistic account of human
morphogenesis, the differentiation of structures, using direct
photographs of normal specimens obtained from legal medical abortions of
unwanted pregnancies. Emphasis has been placed on contemporary
techniques: histochemistry and scanning electron microscopy. The text is
as simple as possible; meticulous detailed anatomic descriptions have
been omitted.
