Morphometric indices of kidney structure formation in Wistar rats during different ontogenetic stages

Introduction. Studying kidneys is crucial, since they are key organs of the urinary system and serve a vital function in maintaining homeostasis. Animal studies play an important role in modeling kidney diseases and evaluating new therapeutic approaches, including medicines. In preclinical research, kidney morphometry serves as a key tool. While Wistar rats are commonly used in such studies, existing data primarily focus on the functional differences between strains, with limited information on morphological features. This research aimed to analyze key micromorphometric parameters of Wistar rats kidneys across different ontogenetic stages and both sexes to establish reference values for normal renal structures. Materials and methods. The study was performed on 120 male and 120 female outbred Wistar rats aged 3, 6, and 12 months and divided into groups of 40 animals. We recorded absolute and relative organ weights and performed micromorphometric analysis of the kidneys using ImageJ/Fiji software (NIH, USA) with the corresponding plug-ins adhering to the standardized renal morphometry protocols. Results. Most of the studied morphological and micromorphometric parameters undergo age-related changes: a decrease in organ mass, the proportion of renal parenchyma, and the number of nephrons and an increase in the area of nephrons and tubules. We also revealed sex differences. Conclusion. We established specific values for a number of morphometric renal parameters of Wistar rats of both sexes, detected sex differences, and identified how these values change over time. The obtained data can be used in further research. Keywords: rat, kidney, morphometry, ontogenesis