Development of the Human Kidney: Morphological Events

Here we will report the main known morphological steps of human nephrogenesis, with a particular attention to the process of epithelial–mesenchymal transition, the complex process originating with an undifferentiated metanephric mesenchymal cell and ending with the origin of the mature proximal nephron, and with its fusion with the collecting tubule. We will try to communicate our present view on the sequence of morphological events regulating human kidney development, and will analyze the multiple cell types until now known to be involved as characters of renal development, defining the known factors that propel these cells during their differentiation from a mesenchymal cell towards the multiple complex epithelial structures of the mature kidney. Sure that what we are here reporting is only a part of the story and that, in the next future, the application of immunohistochemistry and of molecular biology to the study of the developing human kidney will add new data, including new cell types or new differential stages of previously known renal cells, to the complex picture of the human nephrogenesis, with possible relevant consequences on the growth of regenerative renal medicine.