Quantitative analysis of the striate cortex in the mutant microphthalmic rat

A quantitative analysis of the striate cortex of the mutant microphthalmic rat was conducted to determine whether or not transneuronal changes of the visual cortex were induced following the loss of eyes. The area of the striate cortex in the microphthalmic rat was approximately 60% of that in the normal rat. As for the thickness of each layer of the striate cortex, many layers of microphthalmia tended to be thin in comparison with the normal animal, except for layers I and III: the thickness of layers II, IV, V, and VI was about 74, 62, 82, and 82% of normal values, respectively. There was fractically no difference between the number of neurons of each layer of the microphthalmic and the normal striate cortex per unit (10(4) microns2), except for layer IV, in which the density had increased to 117% of the normal value. In many layers, the neurons of the microphthalmic striate cortex were smaller than normal and they had narrow neuroplasmic space. Our study demonstrated that the striate cortex of the microphthalmic rat underwent quantitative and morphometric transneuronal changes. Especially striking changes of the striate cortex were found in the inner granular layer with a reduction in thickness and a diminution of cell size.

Laminar origin of the tecto-thalamic projections in the albino rat

Cells of origin of the tecto-LP (lateroposterior nucleus of the thalamus) projection and the tecto-LGNd (dorsal nucleus of the lateral geniculate body) projection were studied in the albino rat by means of retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). Tecto-LGNd neurons with small spindle form were located in the stratum griseum superficiale of the superior colliculus (SC), whereas tecto-LP neurons with polygonal shape were found in the stratum opticum of the SC.

Quantitative analysis of the lateral geniculate nucleus in the mutant microphthalmic rat

A quantitative analysis of the lateral geniculate nucleus was carried out in the mutant microphthalmic rat. In the dorsal lateral geniculate nucleus (LGNd) of the microphthalmic rat we found the total volume and neuronal population were reduced by 45 and 68% of normal values, respectively. The size of normal LGNd neurons was 8 to 20 microns and that of mutant LGNd cells from 6 to 16 microns. Neurons of the normal LGNd were medium-size and round or oval, and their cell bodies were filled with Nissl substance. Microphthalmic LGNd neurons, on the other hand, had narrow cytoplasmic spaces with few Nissl granules, and pale cell nuclei. In the microphthalmic rat, the lateral part of the ventral lateral geniculate nucleus (LGNvl) also showed a marked reduction in the total volume and neuronal population which were 42 and 76% of normal values, respectively. The size of normal LGNvl neurons was 8 to 20 microns and that of the microphthalmic neurons from 6 to 16 microns. These findings suggested that a marked reduction in the size of the LGNd and LGNvl in the mutant can be attributed to a decrease in neuronal population to a diminution of cell size.

New suspension of operating microscope and chair

We developed a new operating microscope system consisting of magnetically locked suspension for the microscope, an operating chair that makes synchronous coaxial rotation with the microscopy, and has a cryostat and electric coagulator built into its back, and a slit lamp with brighter illumination. The new operating microscope system, which permits a wider range of motion and a clearer view of the operative field than conventional microscopes, has proved useful in such surgical procedures as the running suture in corneal transplantation, loop fixation in intraocular lens implantation, preparation of an intrascleral pocket in detachment surgery, open sky vitrectomy, and decompression of the optic canal.

Ovulation in rabbits following intravenous and intracerebral administration of copper sulphate

The present authors (1965) previously reported that the site of action of copper sulphate in the induction of ovulation might be in the vicinity of the posterior median eminence (PME) in the hypothalamus. The authors have now injected a solution of copper sulphate intravenously into adult female Japanese mongrel rabbits and also infused the solution directly into the PME of the hypothalamus. The 50% effective dose for inducing ovulation in some of the rabbits of the tested group was 0.76 μg/kg of copper sulphate in the PME infusion or 3.0 mg/kg in the intravenous injection. This means that the 50% effective dose of copper sulphate required for infusion into the PME is 1/4000 of the 50% effective dose required by intravenous injection.