Description:
<jats:p> The upper portion of the rat kidney pelvis has specialized anatomic structures referred to as fornices. Fornices have a role in urine concentration. Spontaneous lesions including mineralization, epithelial hyperplasia, and inflammatory cell infiltration may occur in the area of the fornices. However, little information regarding specific historical control data or the spontaneous development of these findings in male and female fornices is known. Understanding spontaneous age-related lesions in the area of the fornices versus other portions of the kidney pelvis may be relevant in the identification of test article–induced changes. A retrospective study was conducted of male and female Sprague-Dawley rat kidney fornices over several time points to determine the incidence and severity of mineralization, epithelial hyperplasia, and inflammatory cell infiltration. Based on this investigation, these lesions appeared to increase over time and, in general, occurred earlier and with a greater incidence in females. Regarding those chemicals that may result in lesions of the kidney pelvis, it may be important for pathologists to separately diagnose lesions of the fornices from other portions of the kidney pelvis to help differentiate between any spontaneous age-related and induced changes. </jats:p>