RESUMO
Intestinal closure is the blocking of biopolymers transferred across the small intestine epithelium that coincides with gut maturation. Sixty-one fetuses of D. albiventris, 45 to 55 mm in Crown-Rump length, were studied. Forty-one fetuses were injected subcutaneously with hydrocortisone hemisuccinate (0.4 mg/15.0 g of body weight) daily for 7 days in order to produce intestinal closure (TA). The control group (CA), consisted of twenty fetuses. Seven days after injection several fragments from the duodenum and ileum were prepared for transmission electron microscopic examination. Microvillus lengths and widths were determined from micrographs (final magnification: 100,000 x). The volume of the microvillus was calculated as the volume of the cylinder. Quantitative differences of the microvilli between the treated and control groups taken from duodenum and ileum material were noted. The distribution of the microvilli in the apical part of the enterocytes was more irregular in controls than in the TA group. Quantitatively, microvillus length in the duodenum was more than 50 per cent greater in TA than in CA and more than 30 per cent greater in TA than in CA in the ileum. Consequently, microvilli volume in the duodenum in TA was about 65 per cent greater than in CA and about 33 per cent greater than in CA in the ileum. Microvilli width presented little change and no statistically significant differences were found between TA and CA in either the duodenum or the ileum. These changes in the microvilli of the treated animals most probably indicate improvement in the absorptive function of the epithelium.