Abstract: 30 healthy (42±4) day-old weaned rex rabbits with the average initial body weight of (711.4±108.8) g were randomly allocated to 3 groups with 5 males and 5 females each group. All rabbits were raised in separated cages. The diets for each group contained same level of crude protein and energy. The diets contained 25% raw soybean, 25% chemically-processed soybean and 25% soybean-meal. The TI concentration (mensurated value) was 6.55, 1.99 and 0.81 mg/g respectively. The experiment lasted for 6 weeks, and at the end of the experiment 3 male rabbits randomly chosen from each group were slaughtered((91±4) day old, average body weight of 1544.2 g±114.8 g))after 4 to 6 hours of fast to take pancreas samples. These samples were fixed in 10% neutral formaldehyde solution, using conventional paraffin slice and HE dye for optical microscope observation. Samples for electronic microscope observation were fixed in 2.5% glutaraldehyde, conventionally resin embedded, very thin sliced, and uranium-plumbum dyed. Optical microscope observation showed the hyperplasia of fibroid connective very thin sliced, and uranium-plumbum dyed. Optical microscope observation showed the hyperplasia of fibroid connective tissue among the pancreas, oedema between lobes, disappearance of part of the gland, cell oedema, and border illegibility of the rabbits fed with 25% raw soybean. Abnormity of pancreas karyon, chondriosome oedema, disappearance of crista, partial membrane rupture, decrease of endoplasmic reticulum, and significantly cutting down or vanishing of particle secretion were discovered by electronical microscope observation in rabbits fed by 25%raw soybean diet. 25% raw soybean did not significantly increase the weight of pancreas, but abnormal changes occurred in histological structures. As for the other 2 groups, the results remained the same that no abnormal changes were found in histological structures. 

Key words: soybean; trypsin inhibitors; Rex rabbits; pancreas; histology