HUMAN EMBRYOLOGY

the process encompassing the period from the formation of an embryo, through the development of a fetus, to birth. The human body, like that of most animals, develops from a single cell produced by the union of a male sex cell and a female sex cell. Human development follows closely the basic vertebrate pattern, and it departs only in certain details from the type specifically characteristic of mammals. A prenatal period, in which most of the developmental advances occur, is followed by a long postnatal period. Only at about the age of 25 are the last progressive changes completed. Additional reading Overviews of the topic are provided by Manuel Hernndez (M. Hernndez Rodrguez) and Jess Argente (eds.), Human Growth: Basic and Clinical Aspects (1992), conference proceedings; Frank Falkner and J.M. Tanner (eds.), Human Growth, 3 vol. (197879), with vol. 1 and 3 in a 2nd ed. (1986); and Esmail Meisami and Paola S. Timiras (eds.), Handbook of Human Growth and Developmental Biology, 3 vol. in 7 (198890).Explorations of human embryology in particular include Stephen G. Gilbert, Pictorial Human Embryology (1989), an atlas containing colourful line illustrations of histological sections and stages of human embryos, for the health professional and the general reader; Keith L. Moore and T.V.N. Persaud, The Developing Human: Clinically Oriented Embryology, 5th ed. (1993); Jan Langman, Langman's Medical Embryology, 7th ed. by T.W. Sadler (1995), a concise presentation; and Jan S. Zagon and Theodore A. Slotkin (eds.), Maternal Substance Abuse and the Developing Nervous System (1992), describing the effects of maternal drug consumption on fetal, neonatal infant, and subsequent adult nervous systems.