Adaptive behavioral reactions of reaching in rats following discrete somatosensorimotor cortex lesions.

To test the effects of lesions of forelimb somatosensorimotor subareas on the reaching behavior, the rats were trained to reach for food pellets in a horizontal tube and through a grid. Reaching attempts were monitored by continual movement recording using magnetic induction and reaching success was quantitatively evaluated. In rats with bilateral lesions centered over the forelimb motor subarea (FMCL), reaches with the preferred forepaw were accompanied by reaching attempts with the nonpreferred forelimb. The latter declined over the recording period but larger residual movements were still observed at the end. Relative to control group, the performance of rats with FMCL was significantly decreased in both reaching tasks, however the reaching success into tube was significantly lower than through a grid. Rats with lesions centered over forelimb cutaneous representation (FCRL) showed signs of tactile deficit. Chosen reaching tactic represented an attempt to compensate for the tactile deficit. No reaches with the nonpreferred forepaw were observed. Relative to controls, the reaching success in rats with FCRL was decreased by the same amount in both reaching tasks. When reaching into the tube, the rats with FCRL performed significantly better than rats with FMCL over the whole recording period; when reaching through the grid no statistical difference in performance was observed between groups though the rats with FMCL performed better than the rats with FCRL. The discrete somatosensorimotor cortex lesions did not only result in different direct reaching deficits and performance, but also resulted in different behavioral reactions.

The function of the cerebrospinal fluid space and its expansion.

In addition to its nutritive and protective effects, the basic function of the cerebrospinal fluid space resides in dynamic equilibration of pressure fluctuations caused by volume changes in three compartments contained within the rigid skull cavity: brain tissue, blood and cerebrospinal fluid. An increase in volume in one of them brings about a compliant withdrawal in volume in the other two. The degree of cerebrospinal fluid compliance can be expressed by means of the pressure/volume index which is directly proportional to this compliance. On the other hand an expansion of fluid space which forces the brain to withdraw its tissue, brings about the dilatation of brain ventricles. The degree of their dilatation depends on the effective pressure of cerebrospinal fluid which counteracts with the resistance of brain venous collectors. The blood in the venous network of the brain and cerebral extracellular fluid play a reversible role in cerebral mass restoration and reduction. These facts explain the reason why, from the physical point of view, the brain is considered to represent a viscous and elastic spongious matter. (Ref. 21.)

Method of determining topometric values of some structures of the human spinal cord.

A method of measuring the cross-section areas of some structures of the human spinal cord is described for the purpose of obtaining the coordinate values by means of simultaneously photographing the transverse section of the spinal cord, together with a microscopic objective square raster. The obtained coordinate values have been processed by means of a computer and represent the statistical model map of some structures of the human spinal cord. By means of the present method, the classic anatomical and topometrical figure of the spinal cord is converted to a coordinate system that may be defined mathematically.

Topometry of normal intrahepatic bile ducts.

This paper focuses on practical problems which may also prove to be of theoretical importance, by presenting a method of establishing an exact topometry of the intrahepatic bile ducts. Measurements were made on corrosive casts of the intrahepatic bile ducts from 13 human livers. On the basis of the topometric results presented it is possible to construct an adequate model by means of plastic tubes and to use it for the study of bile flow.

Histopathology of mammary tumours in female rats treated with 1-methyl-1-nitrosourea.

OBJECTIVE: To induce, evaluate and classify advanced stages of mammary gland tumours induced by MNU. METHODS: Female Sprague-Dawley rats were injected intraperitoneally with 1-methyl-1-nitrosourea (MNU; 50 mg.kg-1) on the day 33, 40, 47, 54 and 61 of age in the first experiment and on 50th and 113th day in the second experiment. On the 117th day (first experiment) and on the 153rd day of age (second experiment) the rats were sacrificed by decapitation and their mammary glands were evaluated both macroscopically and microscopically for the presence of grossly detectable mammary tumours. Mammary tumours were classified according to Russo et al. (1990). RESULTS AND CONCLUSIONS: The final incidence of palpable carcinomas was ranging from 60 % to 76 %. All microscopically evaluated tumours were malignant. Among the total number of lesions classified the percentage of invasive tumours ranged from 35 % to 44 %. No metastases were observed in other organs in MNU treated animals.