Full Description
The concept of the foeto-placental unit as an integrated endocrine organ has been defined recently by many in vivo studies at the 17th- 20th week of gestation. A functioning foeto-placental unit is necessary for most of the increased oestrogen production of pregnancy and for the provision of glucocorticoids and aldosterone to the foetus. Neither the foetus nor the placenta alone have the necessary enzyme systems for the synthesis of these groups of steroids. However, when the foetus and placenta function as a unit, all of the enzyme systems are present for the synthesis of these steroids from circulating cholesterol. The placenta, but not the mid-gestation foetal adrenal, can synthesize physiologically significant amounts of pregnenolone from circulating cholesterol. Part of the pregnenolone is converted to progesterone in the placenta by the 3‾-HSD system (absent in the foetus). The progesterone is transferred to the foetus where it is transformed by C-II, C-17, C-18 and C-21 hydroxylases (all absent in the placenta) to cortisol, corticosterone and aldosterone. Pregnenolone transferred from the placenta to the foetus undergoes 171X-hydroxylation, side chain splitting and sulfurylation (absent in the placenta) and is converted to DHAS. The DHAS may undergo 161X-hydroxylation (absent in the placenta) in the foetal liver and be transported to the placenta as 161X-OH-DHAS. There it is subjected to a neutral steroid sulfatase (absent in the foetus) and is converted to oestriol by action of the 3‾-HSD system and the aromatizing enzyme system.
Contents
Session I Role of the Placenta.- Aspects of steroid metabolism in the foetoplacental unit and the newborn infant.- Problems in the pathologic study of the placenta.- Session II Assessment of Foetal Development.- Growth pattern of the normal and the deprived fetus.- The assessment of foetal age by the examination of the central nervous system.- Developmental changes in fetal hemoglobin.- Developmental changes in liver enzyme activities with special reference to the perinatal period of life.- Development of enzymes and absorption processes in the small intestine of human fetus.- Session III Experimental Aspects of Dysmaturity.- Dysmaturity in the experimental animal.- Effects of prematurity and dysmaturity in animals.- Session IV Hereditary and Environmental Aspects of Low Birthweight.- Factors influencing fetal growth.- The regulation of foetal growth.- Session V Adaptation of the Low Birthweight Infant to Extra-Uterine Life.- The metabolic rate in praemature, dysmature and sick infants in relation to environmental temperature.- Glucose control in the newborn infant.- Neuropathological findings in severe neonatal hypoglycaemia with remarks concerning lesions due to hypoxia.- Hyperbilirubinaemia in dysmature versus premature infants.- Session VI Obstetrical and Preventive Aspects of Dysmaturity.- The obstetrician and dysmaturity.- Session VII Developmental Aspects.- Causes of handicap in the low weight infant.- Neurological findings in newborn infants after pre-and paranatal complications.- Closing Session Summing-Up and General Discussion.- Summing-up H. K. A. Visser.- Summing-up by G. J. Kloosterman.- General discussion.- Summing-up by N. C. R. Räihä.- Summing-up by R. Schwartz.- General discussion.- Summing-up by A. Minkowski.- Index of authors.- Index of subjects.
