[On the origin of islands and septa of the human placenta (author's transl)]

The maternal or foetal origin of septa and islands of the human placenta was examined by counting the sex chromatin in their nuclei (Barr bodies); the origin of the septa was, in addition, determined by counts of the Y-chromatin previously stained with quinacrine fluorescence. Histological investigations were made on preparations stained after Masson-Goldner (trichrom). The results showed that in most cases the upper parts of the septa are exclusively composed of trophoblastic cells, whereas the lower third is preponderantly composed of decidual elements. Purely trophoblastic septa are rare. Islands are trophoblastic. Islands in which both cell types are present, or decidual islands appear to be very rare.