SEX STEROID INDUCTION OF GALLSTONES IN THE MALE SYRIAN-HAMSTER

Light (LM), transmission (TEM) and scanning (SEM) electron microscopic techniques were used to characterize morphologic changes induced in t he gallbladder of Syrian hamsters following a one-month estradiol (E) and estradiol + medroxyprogesterone (E+MP) treatment. The TEM results were correlated with the SEM findings. Compared to control (C), E-trea ted surface epithelial cells contain abundant RER, enlarged Golgi, mul tivesicular (foamy-heterophagosomes) bodies or lipofuscin inclusions. A 10-day E treatment showed large vesicles develop and, after longer E treatment, they could coalesce and create some of the large multivesi cular bodies. Interestingly, E+MP epithelia are characterized by disti nct bulging apices where a large number of apical granules accumulate, and contain an anionic mucous core. After a 4-week E+MP treatment, ev en though all the hamsters were fed a diet with trace cholesterol, sig nificant increase in hamster liver weight, serum level of cholesterol and HDL were measured and, correspondingly, gallstones were found excl usively in E+MP-treated hamsters. Our results showed that not only doe s the Syrian hamster provide an appropriate model to study experimenta l lithogenesis without manipulating the diet. In addition, MP appears to induce morphologic changes associated with the formation of gallsto nes.