Changes in the weight of internal organs in the fetal ontogenesis.

The purpose of this work was the investigation of the development of the weight of brain, heart, lungs, liver, spleen, kidneys, adrenal glands and thymus, and the developmental relations occurring between them in human fetuses and newborns. The material covering 1908 individuals of both sexes (632 fetuses and 1276 newborns) was collected in the Department of Pathological Anatomy in Poznań. During clinical autopsies the weight of organs was determined exactly to 0.1 g and the body weight exactly to 5 g. The age of the individuals was determined on the basis of the mean conception time (14-15 day after the beginning of the last menses) and it ranged from 17 to 43 weeks of gestation. The material was divided into 7 developmental periods. The first 6 periods cover the moon months successively from the 5th to the 10th and the last period covers the three final weeks (41-43). The problems were analysed on the basis of a comprehensive statistical analysis and the obtained results of the significant statistical dependences between the organs were confronted with the biological changes of the investigated features taking place in the period of fetal ontogenesis.