Variants of the structure of the urinary system organs in human fetuses

Aim: To find out the features of individual anatomical variability of the urinary system organs in the fetal period of human ontogenesis.

Materials and Methods: 102 human fetuses with a parieto-calcaneal length (PCL) of 160.0-480.0 mm (4-10 months of gestation) were studied. A complex of morphological research methods was applied, which included anthropometry, morphometry, injection of blood vessels with dyes for visualization of blood vessels of macrospecimens, preparation of macrospecimens, and statistical analysis.

Results: Our material revealed a number of variants of the shape and structure of the ureters, in particular, doubling of the renal pelvis and ureters - 4 observations. The reasons for this may be impaired morphogenesis of the metanephros at the end of the 6th - beginning of the 7th week of intrauterine development. Bends of the proximal part of the ureter, megaureter were observed in 2 cases, polymegacolix, megacolix - in 2 cases. Aberrant renal vessels were detected in 8 specimens. The reasons for their occurrence may be impaired angiogenesis at the end of the 6th week of prenatal development.

Conclusions: 1. Variants of the structure and topography, as well as malformations of the upper urinary tract, were detected in 15.7% of 102 studied fetal specimens. 2. The ratio of detected variants and anomalies of the structure and topography in female fetuses prevailed over those in male fetuses in the ratio of 5:3. 3. Extreme forms of anatomical variability of the structure of renal vessels and their syntopy with the renal pelvis and ureter in all observations were a potential danger of vasorenal conflicts, which would subsequently lead to hydronephrotic transformation of the kidney.