Stereological estimates of nuclear volume in normal mucosa and carcinoma in situ of the human urinary bladder.

The nuclear volume of the epithelial cells in the human urinary bladder mucosa has been estimated using point sampled intercepts in vertical sections (local vertical windows). The study included 27 specimens: ten from normal bladder mucosa, five from inflamed mucosa, seven from mucosa with flat grade II lesions and five from mucosa with flat grade III lesions. After standard fixation, embedding, sectioning and haematoxylin-eosin staining an unbiased estimate of the mean volume of nuclei sampled with a chance proportion to the volume = vV = pi/3 x (l0)3 was calculated using a frame for orientating the linear test probe in vertical sections. Here l0 is the length of the intercept through a test point hitting a nucleus measured in a random direction through the test point. The weighted mean nuclear volume of bladder mucosa with grade II and grade III lesions (537 microns 3 and 494 microns 3 respectively) was significantly larger than the weighted mean nuclear volume of normal (133 microns 3) and inflamed bladder mucosa (182 microns 3). This simple and fast estimation of nuclear volume seems to provide objective data useful in discriminating between neoplastic and non-neoplastic lesions of the bladder mucosa.