Cellular Development of Some Human Organs Before Birth

Abstract

. (1972). Archives of Disease in Childhood, 47, 652. Cellular development of some human organs before birth. The total amount of DNA and the protein/DNA ratio have been measured in the kidneys, heart, liver, and gastrocnemius muscles of 56 human fetuses and newborn infants of 13-42 weeks' gestational age. The total amount of DNA in each organ approximately doubled every week up to the 25th; thereafter the rate of increase was slower. The protein/DNA ratio in each organ increased rapidly in the last 10 weeks of intrauterine life. Before 30 weeks there was some increase in the protein/DNA ratio in the kidneys, heart, and gastrocnemius muscles, but no significant change in the liver. In 5 small-for-dates infants the protein/DNA ratio was normal, whereas the total DNA tended to be low.The cellular growth of the brain of the human fetus (Winick, 1968;Dobbing and Sands, 1970;Dobbing, 1970), and of the placenta (Winick, Coscia, and Noble, 1967), have been investigated systematically by chemical means, but other organs have been neglected. This paper reports observations on the growth of the human kidneys, heart, liver, and gastrocnemius muscles before birth. Total DNA was used as an index of the number of cells in the internal organs and the protein/DNA ratio as an index of the mean cell size. The quantity of DNA was taken to indicate the number of nuclei in the gastrocnemii, and the protein/DNA ratio the relation between cytoplasm and nucleus. Materials and MethodsOrgans from 28 fetuses delivered by hysterotomy for the therapeutic termination of pregnancy, and from 28 fresh stillborn and livebom infants who died within the first week of life were collected. All the fetuses were normal on clinical judgment. Infants with major congenital abnormalities or rhesus incompatability were excluded. Five of the liveborn infants were small for their gestational age, and this was presumably due to nutritional deprivation before birth. Specimens were also collected from 5 adults, 2 men and 3 women, aged 39 to 75 years, for comparison.The kidneys, heart, liver, and gastrocnemii were collected within one hour of death from the fetuses, weighed to the nearest mg, wrapped in plastic film ('Snapwrap'), frozen in liquid nitrogen, and stored at -20°C until analysed. The same organs were collected from the liveborn infants and adults at necropsy (which was usually performed within 24 hours of death), weighed, and portions were then treated similarly.The frozen organs were reweighed and were then thawed sufficiently to be homogenized, but the gastrocnemii were ground to a powder in liquid nitrogen. Portions of all the thawed, homogenized tissues were taken for determination of protein and DNA. Protein was precipitated from one sample with 10%/ trichloroacetic acid, and nitrogen was determined on the precipitate by the micro-Kjeldahl method (Chibnall, Rees, and Williams, 1943 Fig. 1-4 show the total DNA and the protein/ DNA ratios (mg protein/mg DNA) in the gastrocnemii, kidneys, heart, and liver plotted against gestational age. A semilogar...

Relationships between Maternal and Fetal Liver Copper, Iron, Manganese, and Zinc Concentrations and Fetal Development in California Holstein Dairy Cows

“…14,15 Human fetuses obtained after therapeutic abortion had similar liver Mn concentrations (n = 30; 0.0236 µmoles Mn/g wet weight; 1.3 µg/g) as bovine fetuses in this and the Canadian study. 14,15,51,52 Similarly, women had equivalent hepatic Mn (0.0328 µmoles Mn/g wet weight; 1.8 µg/g) as did pregnant Canadian cows, but these concentrations were half that of cows in this study. 51,52 Similar to bovine fetuses in the present study, human fetal hepatic Mn did not change through gestation.…”

“…14,15,51,52 Similarly, women had equivalent hepatic Mn (0.0328 µmoles Mn/g wet weight; 1.8 µg/g) as did pregnant Canadian cows, but these concentrations were half that of cows in this study. 51,52 Similar to bovine fetuses in the present study, human fetal hepatic Mn did not change through gestation. 51,52 Fetal hepatic Mn concentrations in stillborn infants and neonatal infants dying within 24 hours of birth were similar to adult values.…”

Early adiposity rebound in childhood and risk of Type 2 diabetes in adult life

“…One possible explanation for the association between small body size at birth, early adiposity rebound and later Type 2 diabetes is that there are persisting alterations in body composition [4]. Babies that are small and thin at birth lack muscle, a deficiency which will persist as the critical period for muscle growth occurs in utero and there is little cell replication after birth [17]. If they develop a high body mass during childhood they can have a disproportionately high fat mass in relation to lean body mass, which will lead to insulin resistance [12,18,19].…”

* The developmental origins of well-being

“…Rapid weight gain may lead to an unfavourable body composition. Babies that are small and thin at birth lack muscle, a deficiency that will persist because the critical period for muscle growth occurs in utero and there is little cell replication after birth (Widdowson et al 1972). If they develop a high body mass during later childhood they may have a disproportionately high fat mass in relation to lean body mass, which will lead to insulin resistance .…”