Development of GFAP-positive cells and reactive changes associated with cystic lesions in HTX rat brain.

HTX rat, a congenital hydrocephalic strain, develops ventricular dilatation and cystic cavities in the cerebral white matter after birth. To investigate the reactive changes in glial cells around these cavities, immunohistochemical staining for glial fibrillary acidic protein (GFAP), a specific marker protein of astrocytes, and bromodeoxyuridine (BrdU), a thymidine analogue, was carried out on 107 Wistar and HTX rat brains from birth to postnatal day (P) 26. Animals were divided into three groups: Group A, Wistar rats as normal controls; Group B, HTX rats with a normal structure or only mild ventricular dilatation without any lesion in the white matter; and Group C, HTX rats with severe ventricular dilatation and cyst formation in the white matter. Group B rats showed similar development of GFAP-positive (GFAP+) cells to that in Group A rats, both morphologically and quantitatively. On the other hand, Group C rats showed definite structural changes in GFAP+ cells around the cystic cavities from P5. These included enriched cytoplasm and thickened cell processes with increased GFAP expression, and enveloped most cyst walls from P10. However, quantitative examination of the percentage of GFAP+ cells in Group C rats showed a similar developmental profile to those in Group A and B rats. Furthermore, the labeling index of BrdU-positive cells, indicating S-phase cells, in the white matter in Group C rats showed a similar decreasing pattern to that in Group A and B rats from P1 to P26.(ABSTRACT TRUNCATED AT 250 WORDS)

Histopathology of cystic cavities in the cerebral white matter of HTX rats with inherited hydrocephalus.

To investigate the mechanism of cystic cavity formation in the cerebral white matter of the HTX rat, a strain with inherited hydrocephalus, the authors carried out a histopathological study of the brain in pups from birth to postnatal day (P) 26. Cystic cavities were formed in the cerebral white matter on the lateral side of the basal ganglia of all HTX rats with moderate to severe ventricular dilatation and, additionally, in the white matter beneath the paramedian cortex in advanced cases at P10-26. In the initial stage of cyst formation, disarrangement of the ependymal cell layer and spongy alteration of the white matter took place in pups between P1 and P7. The ependymal disarrangement involved disruption and flattening of the ependymal cells, which were often devoid of microvilli, cilia and intercellular junctional complexes. The spongy state was due to expansion of the extracellular space and multiple microcyst formation with fluid accumulation in the early stage, and large cystic cavities in the advanced stage. The cerebrospinal fluid (CSF) in the ventricle communicated with the fluid in the cystic cavities via the disarranged ependymal cell layer. The ependymal damage was more prominent at the lateral wall of the posterior horn than at the anterior horn of the lateral ventricles. These cavities were demarcated by reactive glial cells in the advanced stage. However, the cavities enlarged in accordance with progressive dilatation of the lateral ventricles during postnatal development.(ABSTRACT TRUNCATED AT 250 WORDS)

[Emulsifiers which reduce the latency of the development of colonic cancer--sodium lauryl sulfate and methylazoxymethanol].

The effect of emulsifier (nonionic surfactant) on the production of adenocarcinoma by methylazoxymethanol acetate in the large intestine of rats was studied. Following emulsifier, sodium lauryl sulfate administration, many cases of undifferentiated adenocarcinoma consisting of anaplastic glandular cells were induced in the experimental groups. Lymphatic invasion by cancer cells was found in 3 cases and metastasized to other organs in 6 cases. On the contrary, the control group (administered methylazoxymethanol acetate only) revealed well-differentiated adenocarcinoma in many cases. This fact may be due to an emulsifier used as a vehicle for the chemical, and the emulsifier might activate the character of promotion to carcinogenisity as a secondary agent. By virtue of the strong penetrating property of the emulsifier, colonial carcinogenesis seems to be enhanced.