Histological Analysis of the Prostate During the Human Fetal Period (12 to 22 Weeks Post-Conception)

The aim of this study was to quantitatively analyze the stromal components of the prostate (collagen, muscle fibers and elastic system fibers) during prostate development in normal human fetuses, in order to establish normal growth patterns.

Twenty-one normal human fetuses, aged between 12- and 22-weeks post-conception (WPC), were studied. The fetuses were divided into three groups: G1, n = 7, 12 to 16 WPC; G2, n = 6, 17 to 19 WPC, and G3, n = 8, 20 to 22 WPC. The samples were fixed in 4% buffered formalin and processed for paraffin embedding for histochemical analysis. Five 5-micrometer-thick sections were taken from each sample and stained using histochemical techniques to identify the prostate stromal components. Histomorphometric analyses were carried out by evaluating the area density of the parameters analyzed, in percentage, using ImageJ software.

The quantitative analysis of collagen fibers (p = 0.0616) and elastic system fibers (p = 0.6049) showed no significant difference between groups. Smooth muscle fibers were higher in G2 (+82.38%) and G3 (+108.81%) when compared to G1, p = 0.0020. Linear regression of the entire fetal period studied (12 to 22 WPC) showed a proportional increase in muscle fibers in relation to gestational age (r2 = 0.3398; p = 0.0056). Linear regression revealed a strong negative correlation between collagen fibers and smooth muscle fibers in G3 (20 to 22 WPC) (r2 = 0.8209; p = 0.0019).

Changes in the stromal components of the prostate are more significant from the end of the second trimester of pregnancy. Collagen fibers and elastic system fibers showed stable growth throughout the fetal period studied. The density of smooth muscle fibers increased about twofold with increasing fetal age.