Abstract
The juxtaglomerular apparatus (JGA) is a specialized renal structure essential for the regulation of systemic blood pressure and glomerular filtration rate through the renin-angiotensin-aldosterone system (RAAS). It consists primarily of three cellular components: juxtaglomerular (granular) cells, macula densa, and extraglomerular mesangial (lacis) cells. with the aim of understanding the influence of environmental and physiological conditions on renal regulatory architecture. A total of 12 adult rats were used 6 wild rats captured from natural environments and 6 laboratory rats maintained under controlled conditions. Following euthanasia, kidneys were excised, fixed in 10% formalin. Tissue sections were stained using (H&E) for general morphology and Masson’s trichrome for highlighting connective tissue components. Microscopic examination was conducted using light microscopy, focusing on the cortex, where JGA structures are typically located at vascular pole adjacent to glomeruli. Results showed that wild rats exhibited a significantly higher density of JGA structures compared to laboratory rats. In addition, the wild group displayed a more cellular and structurally complex macula densa region, with an increased number of juxtaglomerular cells suggesting elevated secretory activity. These differences are likely attributed to environmental and physiological adaptations. Wild rats are exposed to variable hydration, physical activity, stress, and dietary conditions that may stimulate more frequent activation of the RAAS, thereby reinforcing the development and activity of the JGA. Conversely, laboratory rats live in a controlled environment with consistent food and water availability, minimal stress, and regulated temperature, potentially reducing the physiological demand on renal regulatory systems and leading to less pronounced JGA features. Histological findings were further supported by the architectural differences observed in Masson’s trichrome-stained sections, which showed more developed periglomerular connective tissue around the JGA in wild rats. These structural variations may reflect long-term adaptation to environmental stimuli.