Comparative morphogenesis of the urinary system in humans and laboratory mice

Abstract

In press

Background. The organs and structures of the urinary system in humans and mammals undergo similar stages of ontogeny. However, the laboratory mouse, as a model for morphological research, does not always accurately replicate changes in the human body; therefore, improving the methodology of comparative studies remains highly relevant.

Aim. To conduct a comparative analysis of the developmental origins and chronological sequence of topographic-anatomical transformations within the structures and organs of the urinary system in humans and laboratory mice.

Materials and Methods. Serial histological sections of 18 human embryos and 20 laboratory mouse embryos were examined microscopically. The developmental stages of both species were determined using the Carnegie Staging (CS) system. Statistical analysis was not performed because the study was descriptive. The study was conducted within the framework of the research with state registration No. 0126U003125.

Research Ethics. The study was conducted in compliance with the General Ethical Principles of Animal Experiments (Ukraine, 2001) and the World Medical Association Declaration of Helsinki (1964–2024). The Biomedical Ethics Committee of Bukovinian State Medical University (Protocol No.7 of May 19, 2026) found no violations of bioethical norms during the study.

Results. At stage CS13, the cranial border of the mesonephros in both human and laboratory mouse embryos is located at the T1/T2 level; due to mesonephric regression by stage CS19 it is visualized at the L4/L5 level. The caudal border of the mesonephros in human embryos was located at the S1–S3 level throughout its development, whereas in laboratory mouse embryos at stages CS9–CS19 it showed a tendency toward caudal growth until it reached the S1–S3 level. In humans, at stages CS12–CS19, well-developed glomeruli are visualized in the middle portion of the mesonephros, and the tubules penetrating from the mesonephric duct exhibit a more complex, branched structure than those in the laboratory mouse.

Conclusions. The mesonephroi of humans and laboratory mice displayed similar patterns regarding the initiation and development of the cranial portion of the mesonephros. However, while the caudal portion in human embryos had stable initiation boundaries, in mouse embryos at stages CS9–CS10 this boundary was located more cranially, and due to progressive growth by stage CS19, the topography of the caudal border reached the S1–S3 level.

Keywords: theoretical medicine, anatomy, embryology, mesonephros, metanephros, embryogenesis.