Date Published: August 29, 2014
Publisher: Public Library of Science
Author(s): Carla B. M. Gallo, Waldemar S. Costa, Angelica Furriel, Ana L. Bastos, Francisco J. B. Sampaio, Miklos S. Kellermayer.
The penile erectile tissue has a complex microscopic anatomy with important functions in the mechanism of penile erection. The knowledge of such structures is necessary for understanding the normal physiology of the adult penis. Therefore, it is important to know the changes of these penile structures during fetal development. This study aims to analyze the development of the main components of the erectile tissue, such as collagen, smooth muscle fibers and elastic system fibers, in human fetuses.
We studied the penises of 56 human fetuses aged 13 to 36 weeks post-conception (WPC). We used histochemical and immunohistochemical staining, as well as morphometric techniques to analyze the collagen, smooth muscle fibers and elastic system fibers in the corpus cavernosum and in the corpus spongiosum. These elements were identified and quantified as percentage by using the Image J software (NIH, Bethesda, USA). From 13 to 36 WPC, in the corpus cavernosum, the amount of collagen, smooth muscle fibers and elastic system fibers varied from 19.88% to 36.60%, from 4.39% to 29.76% and from 1.91% to 8.92%, respectively. In the corpus spongiosum, the amount of collagen, smooth muscle fibers and elastic system fibers varied from 34.65% to 45.89%, from 0.60% to 11.90% and from 3.22% to 11.93%, respectively.
We found strong correlation between the elements analyzed with fetal age, both in corpus cavernosum and corpus spongiosum. The growth rate of these elements was more intense during the second trimester (13 to 24 WPC) of gestation, both in corpus cavernosum and in corpus spongiosum. There is greater proportional amount of collagen in the corpus spongiosum than in corpus cavernosum during all fetal period. In the corpus spongiosum, there is about four times more collagen than smooth muscle fibers and elastic system fibers, during all fetal period studied.
While formed by only 2 types of non-stromal cells; smooth muscle cells and endothelial cells, the erectile tissue of the penis (corpus cavernosum and corpus spongiosum) has a complex microscopic anatomy, forming a network of sinusoidal spaces. The erectile tissue of the human penis is composed of elastic fibers, collagen fibers, smooth muscles, arteries and veins, and has important functions in the mechanism of penile erection –. The trabeculae of the erectile tissue are major penile structures involved in erection and are formed by the extracellular matrix and smooth muscle fibers. These elements give support to nerves, sinusoids, arteries and endothelium , . Histochemical and immunohistochemical analyses, of which some were associated with morphometry, have characterized structural components in the erectile tissue of adult penis , ,  and also, in preliminary works , , these techniques have been used to investigate erectile tissue in human fetal penis.
This research was performed at Urogenital Research Unit, State University of Rio de Janeiro. The Ethics Committee of Pedro Ernesto University Hospital (State University of Rio de Janeiro) approved the project and waived the need of informed consent.
Previous studies from our group, in various organs of the urogenital system, including the penis, over the past 25 years, showed the importance of establishing growth patterns in normal human fetuses , , –. In addition, we studied the urogenital system in fetuses with congenital anomalies, as prune-belly syndrome and anencephaly, and compared these results with normal fetuses, with the view to possible use of anencephalic, for example, as potential donors of tissues and organs –.
We found strong correlation between collagen, smooth muscle fibers and elastic system fibers growth with the fetal age, both in corpus cavernosum and in corpus spongiosum. The growth rate of all elements analyzed was more intense during the second trimester (13 to 24 WPC) of gestation when compared to the third trimester (25 to 36 WPC), both in corpus cavernosum and in corpus spongiosum.