Orofacial clefts. A theoretical basis for their prevention and treatment.

Abstract

In spite of the existing huge number of data on palate development as well as the incidence, experimental induction and clinical treatment of orofacial clefts, no unitary concept has been made available that would make possible their sorting out, further interpretation and extrapolation. The aim of this monograph has been to provide firm grounds for managing the data within categories consistent with the general principles of teratogenesis reformulated and extended upon the theory of morphogenetic systems, and, upon this basis, to evaluate the present chances of preventing the origin of orofacial clefts. Chapter 1 introduces the problem of birth defects that possess some distinct features in common with the recognised prime problems of present medicine, that is neoplastic and cardiovascular diseases. Orofacial clefts represent a substantial component of the human birth-defect spectrum that is a mere remnant of the original volume of teratogenesis estimated as affecting about 35% of human embryos. The merciful process of prenatal extinction of abnormal conceptuses, or terathanasia, reduces this eminent figure by approximately one order of magnitude. Basing upon the prevalence of clefts in embryos and infants we may say that the prenatal extinction of individuals with orofacial clefts lies somewhere between 70-90%. Chapter 2 deals with the history of recognising and formulating the general principles of teratology that go back to Isidore Geoffroy Saint-Hilaire. Estimating the contribution of the great personalities such as Dareste, Schwalbe, and J. G. Wilson, the chapter enumerates and describes the ten principles of teratogenesis as having arisen from the known rules extended and reformulated by the original theory of morphogenetic systems. In their sum, the principles constitute a deductive system defining teratogenesis at several levels of bioorganisation, capable of predicting the large-scale effects of environmental impact on animal and human reproduction. Chapter 3 presents the orofacial clefts in the light of the theory of morphogenetic systems. Palatal morphogenesis is accomplished under the conditions of extraordinary spatial complexity and extends over a relatively long period of development. Several morphogenetic subsystems may be distinguished, namely the morphogenetic subsystem (smgs) of facial outgrowths, the smgs of palatal shelves, the smgs of the glossomandibular complex and, eventually, the smgs of the axial cervical region, acting at different phases of palatal development.(ABSTRACT TRUNCATED AT 400 WORDS)