Mucus production of choledochal epithelial cells due to bile stagnation in the rat.

Mucus secretion is increased by various causative agents of inflammation in the mucosa. Although mucus production of the choledochal epithelial cells (except goblet cells) has never been noted in the rat in normal physiological conditions, it is seen as an inflammatory reaction in animals with choledochoenterostomy, which brings bacteria and active digestive enzymes into the common bile duct through regurgitation of intestinal contents. It is known that stagnant bile alone can cause inflammation in the mucosa of the gallbladder in patients with aseptic acalculous cholecystitis. In this study, aseptic bile stagnation was caused by choledochal dilation made by detaching the common bile duct from the hepatoduodenal ligament in five rats, and histological changes of the choledochal epithelium were observed by light and transmission electron microscopy 17 months after the operative procedure to determine whether stagnant bile could cause mucus production in choledochal epithelial cells. Mucus production was noted in two rats by light microscopy and in all the rats by transmission electron microscopy, and so it was demonstrated that stagnant bile could give rise to this phenomenon in the rat choledochal epithelium.

Ultrastructural study on hyperplastic epithelium of rat common bile duct after choledochoenterostomy.

Hyperplasia of the choledochal epithelium occurs in rats after choledochoenterostomy. It is tubular or papillary and not like small intestinal mucosa in rats with choledochojejunostomy. It is, however, like large intestinal mucosa in rats with choledochocolonostomy. We investigated the ultrastructure of the hyperplastic epithelium in the two experimental groups of rats in this study. The main constituent cells of the hyperplasia of both the groups were like the principal cells of the control, but differed in that they had long microvilli and contained an aggregation of mucus droplets and an increased number of lysosomes. These findings were not seen in the control. The microvilli were sparse in the choledochojejunostomy group, but were dense in the choledochocolonostomy group. These findings suggest that the main function of the epithelium may be cytoprotection in the choledochojejunostomy group and both resorption and cytoprotection in the choledochocolonostomy group.

Long-term observations on morphological changes of choledochal epithelium after choledochoenterostomy in rats.

Morphological changes of the common bile duct were observed macroscopically and microscopically 20 months after choledochojejunostomy and choledochocolonostomy in rats. The common bile ducts were remarkably dilated in all rats of both experimental models. Choledochal stones consisting of fatty acid calcium and calcium bilirubinate were seen in two of six rats with choledochojejunostomy and two of five rats with choledochocolonostomy. The main pathological change observed in both the groups was remarkable hyperplasia of the choledochal epithelium. Only one rat with choledochojejunostomy revealed normal epithelium with choledochal stone formation. Intestinal metaplasia was seen in two rats with choledochojejunostomy and all with choledochocolonostomy. Squamous pseudostratification of the epithelium indicating atypism was observed in two rats with choledochojejunostomy. Sialomucin producing cells and sulfomucin producing cells were seen in the hyperplastic portion of the epithelium. No malignant alteration of the epithelium was detected. These findings indicate that long-lasting exposure to digestive enzymes and bacteria causes epithelial hyperplasia and further exposure to digestive enzymes plays a major role in appearance of the epithelial atypism. Carcinogenesis of the choledochal epithelium under such an environment will need much more time to be established.

Changes in arterioles of the human gastric mucosa with atrophic gastritis.

Arteriolar changes in the gastric mucosa of 18 patients with atrophic gastritis and of 13 control subjects without atrophic gastritis were investigated using electron microscopy. Irregularly configured smooth muscle cell atrophy with lysosomes and interstitial deposition of highly electron dense material were found in mucosal arterioles of the patients with atrophic gastritis. These findings were similar to the findings seen in patients with hypertension, and animals with experimentally-induced hypertension. Similar, but mild, changes were also noted in mucosal arterioles of control subjects. However, such findings were more common in the aged. These results suggest that the arteriolar changes in the gastric mucosa represent fundamental factors causing atrophic gastritis.

Study on changes in basal lamina width of mucosal epithelium and of capillary in the lamina propria of murine stomach in advance of age.

Correlation between advance of age and changes of basal lamina width of mucosal epithelium and capillary was estimated in both the fundic gland and the pyloric gland, respectively, by electron-microscopic morphometry, using C57BL/6N mice. In basal lamina width of mucosal epithelium, no change was found in both the glands throughout life. In basal lamina width of mucosal capillary, change related to aging was not found in the fundic gland, but in the pyloric gland; it increased in the old mice. This fact is considered to be related to physiological and anatomical differences of microcirculation between the two glands.

Pineal synaptic ribbons in blinded rats.

To study the effects of bilateral ophthalmectomy on the circadian rhythm of the pineal gland, the number of the synaptic ribbons and ribbon fields in the pineal gland of female rats were determined by electron microscopy. In a preliminary experiment, the pineal gland was taken from rats at 15 days, and 1, 2, 3, 4, and 6 months after bilateral ophthalmectomy. It was found that the numbers of both synaptic ribbons and ribbon fields decreased markedly and reached a minimum at 1 month postoperatively, but recovered completely after 4 months. In the main experiment, the number of these intracellular elements was counted in both control and enucleated animals killed at 4 h intervals between 02:00 h and 22:00 h at either 1 month or 6 months after operation. All animals were kept under a lighting regimen of 12 h of illumination (06:00 to 18:00) and 12 h of darkness (18:00 to 06:00). After 1 month, a remarkable decrease in the number of both the synaptic ribbons and ribbon fields was again noted but the circadian rhythm still remained. Complete quantitative and qualitative recovery in the circadian rhythm was obtained 6 months later.

Glomerular lesions in multiple myeloma.

An autopsy case of multiple myeloma (IgG, lambda type), clinically characterized by decreased glomerular filtration rate, is reported with particular emphasis on changes in the glomeruli of kidneys. Histologically, the glomeruli revealed slight increase in mesangial matrix and focal thickening of tuft capillary wall. Electron-microscopically, deposits were observed in a subendothelial location in the glomerular capillary walls, and inclusions were noted in the cytoplasm of the visceral epithelial cells. Histoimmunofluorescent study of the kidney demonstrated intense focal and slight diffuse positivity against labelled antisera of anti-IgG and anti-lambda type of light chain on the capillary wall of the glomerular tufts. Other immunoglobulins were not demonstrable in capillary walls. These findings represent the intraglomerular deposition of paraprotein of multiple myeloma without amyloidosis.

A morphological study of the circadian cycle of the pineal gland of the rat.

To seek a morphological expression of circadian rhythm, we investigated cytologically pineal glands taken from rats every 2 to 4 h under a lighting regime of 12 h of illumination (6:00 to 18:00) and 12h of darkness. The changes in the number of synaptic ribbons and ribbon fields was observed by electron microscopy. The number of these intracellular elements was greatest at 2:00 and lowest at 14:00, the difference being statistically significant. There were no significant local differences in numbers with respect to the part of the pineal gland examined. The data are similar to those of Vollrath from the pineal gland of a guinea pig, and seem to confirm a circadian function in the pineal gland in mammals.

Synaptic ribbon in the human pinealocyte.

An electron microscopic study of a pineal gland which had been obtained from a 3-year-old girl at autopsy revealed the presence of synaptic ribbon in it. Namely, in some parenchymal cells observed, synaptic ribbons, each of which was ca. 700 nm in length and with synaptic vesicles of up to 60 nm in diameter gathering on the surface, were found in the cytoplasmic area adjacent to the cell membrane. The substructure of the synaptic ribbon, i.e., parallel striae running inside along the longitudinal direction, was definitely observed. There is a hypothesis which has been almost accepted that the mammalian pinealocyte is homologous to the photoreceptor cell of the pineal organ in lower animals, and one of the morphological evidences which supports this speculation is the presence of sensory cell elements in both. Since, this kind of work has been hardly done with human materials, the above finding may offer a meaningful information which discloses a part of the real function of the pineal gland in man.

Virus-like particles in human pinealoma.

Virus-like particles were seen in the tumour cells of a pinealoma in a male of 18 years. The particles were dense, spherical or hexagonal in shape, and 100-130 nm in size. They were found in the cytoplasm, but not in the nucleus. They occurred in aggregates or in isolation. They tended to form rows or circles. These particles may be viral in nature, and of one of the herpes-, leuro- or arena-groups, especially when judged from their size. However, greater certainty as to their nature is impossible from the morphological evidence.

Morphologic and microspectrophotometric studies on spontaneous melanomas in Xiphophorus helleri.

Melanomas developed in both sexes of a strain of Tuxedo variety of the swordtail (Xiphophorus helleri) at a relative frequency of 10-15%. They did not metastasize. However, the tumor margin had infiltratitive growth and subsequently ulcerated. This feature, together with the histologic and cytologic features and apparent heteroploidy of the tumors, as revealed by their DNA content, indicated that the tumors were indeed neoplastic. Electron microscopic findings on the melanosomes in these melanomas at various stages of development were comparable with those on the Harding-Passey mouse melanoma, which contains granular premelanosomes.