Morphogenesis of penis and spongy urethraduring human gestation

Abstract

Background. Every year, approximately 500,000 children in the world are born withcongenital abnormalities of the urinary system and kidneys. Therefore, pediatricians andurologists must understand the normal processes that lead to male sexual differentiation.Objective. The aim of this study was to describe in detail the process that occurs duringmasculinization of the fetus, which leads to the formation of male structures under normalconditions. Methods. Fifty-four fetuses with gestation periods between four and 18 weekswere collected, which were considered normal, did not have any signs of external anatomicabnormalities or any alteration in their development, and were a product of spontaneousabortions and tubal pregnancies. The urogenital sinus region was collected and preparedfor scanning electron microscopy and high-resolution optical microscopy to observe thecellular characteristics of the urogenital fold during external development in male embryos. Results. This work shows the formation of the glans and spongy urethra in a detailed man-ner from the eighth week of embryonic development, carefully describing the role of the labioscrotal folds and the fusion of the walls of the urogenital fold during the subsequent stages of development to form the proximal part of the urinary tract. Conclusion. The for-mation of the penile urethra from the urethral fold and its posterior fusion have a probable role of ectodermal cells, in addition to the endodermal origin established previously.