The amnion epithelium cells of 3 human embryos (30 mm, 150 mm, 170 mm CR) and 2 newborn infante were investigated. Silver impregnation of the cell borders and the Feulgen stain of the nuclei were combined on whole mount preparations of the amnia. The DNA-content was determined histophotometrically. The nuclear area and the cytoplasmic area were determined by drawings and planimetry. The nuclei can be grouped into diploid, tetraploid and octoploid classes according to their DNA-content. When the DNA-content of the nucleus doubles, the nuclear area increases but does not double. The factor of increase lies between 1.3 and 1.85. By estimating the volume of the nuclei from the area, this factor of increase still remains below 2. The cytoplasmic area, which in the amnion epithelium is proportional to the cytoplasmic volume, increases at about the same rate as the nuclear area increases with each doubling of the nuclear DNA-content. The nucleocytoplasmic ratio is quite constant within 1 preparation. It is considerably smaller in the youngest embryo (30 mm CR1) than in all other cases, mainly because of the larger cell size at this stage.