Morphometric data of normal and neoplastic urinary bladder epithelia have been collected from the Fischer rat
FANFT model. Sequential measurements of volumes, surface areas, and numerical densities of organelles, and where pertinent, cellular compartments have been made during
FANFT carcinogenesis, utilizing standard point and intersection counting methods. The data show that neoplastic transformation of rat bladder epithelium, and progression of
FANFT tumors are associated with increasing volume densities of cells, nuclei, microvilli, rough endoplasmic reticulum, and mitochondria, as well as with decreasing volume densities of the cytoplasmic matrix, fusiform vesicles, Golgi complex, and lysosomes. Surface densities of the plasma membrane (microvillar), nuclei, rough endoplasmic reticulum, as well as mitochondrial outer and inner membranes progressively increase while surface densities of non-microvillar plasma membrane, fusiform vesicles, and Golgi complex decrease with time. Smooth endoplasmic reticulum reaches its maximum volume and surface densities in
tumors present 26 weeks after the initiation of
FANFT feedings (26-F tumors). This may reflect the function of smooth endoplasmic reticulum as the site of detoxification of the
carcinogen, noting that
FANFT is metabolized by microsomal
enzymes, and in this experiment is fed only for 26 weeks. The nuclear/cytoplasmic ratio is 1:4 in normal Fischer rat urothelium, 1:3 in 26-F and 43-F
tumors, which are noninvasive, and 1:2 in 61-F, which are invasive
tumors. The quantitative data correlate well with the changes in degree of differentiation of the
tumors and with their
biological behavior.