Histological Variations of Jejunal and Ileal Mucosa on Days 8 and 15 after Hypophysectomy in Rat: Morphometrical Analysis in Light and Electron Microscopy

Publisher Website
Google Scholar
Abstract
Variations of the intestinal mucosa were studied in male adult Wistar rats on day 8 and day 15 after hypophysectomy. All results were compared with those obtained in pair-fed control rats. Morphological variations were observed at two intestinal levels (high part [hp] and low part [lp] of the jejunoileum) both with morphometrical analysis (villous area, microvillous area, enterocytes, goblet and Paneth cell number, mitotic index...), in light or electron microscopy and with histochemical techniques (proteins, polysaccharides, nucleic acids). Levels of the main intestinal hydrolysis were also measured by means of biochemical assays. Atrophy of the intestinal mucosa was confirmed, but atrophy produced not only a reduction of the villous area (hp = –30%p < 0.01, lp = –22%p < 0.05 on day 8, hp = –25 %p < 0.05 lp = –36% p < 0.01 on day 15) but also a significant decrease of the microvillous area (hp ≈ –39% p < 0.001, lp = –14% p < 0.05 on day 8, hp = –24% p < 0.02, lp = –30% p < 0.05 on day 15) in accordance with a significant decrease of brush border enzyme levels. The atrophy was generalized but concerned mainly the high part of the small intestine and could be attributed mostly to a significant decrease of glandular mitosis (hp = –57% p < 0.01, lp = –77% p < 0.001 on day 8, hp = –74% p < 0.01, lp = -75% p < 0.001 on day 15) without apparent modification of cell extrusion at the top of intestinal villi. Hypophysectomy affected the different cell types of the villous intestinal epithelium in different ways. Absorbing cells were the more reduced in number. Defects of maturation of goblet cells were noted. On the other hand, hypertrophy (p < 0.001) and hyperplasia (p < 0.001) of Paneth cells were observed with a significant decrease of the lytic activity. These apparent discrepancies can be attributed to important cytological variations and partial mucoid transformation of the secretory component of Paneth cells (observed both by histochemical and electron microscopic observation). Cytological variations after hypophysectomy seem to be induced early, since no significant differences could be observed between days 8 and 15 for most of the parameters tested. Direct or indirect (local relay) effect of pituitary function is discussed.