Related Experiment Videos
Electron microscopic study of retinas of macular mice
1Department of Ophthalmology, Nagasaki University School of Medicine, Japan.
Background:
Menkes' disease may be due to a lack or deficiency of copper in various organs. The macular mouse is known as a model for Menkes' disease. We examined melanin granules in the retinal pigment epithelium and the activity of cytochrome oxidase, a copper-containing enzyme, in the retinas of macular mice by electron microscopy.
Methods:
In the retinas of hemizygote macular mice we demonstrated cytochemically (oxidative polymerization of diaminobenzidine to an osmophilic reaction product) the activity of cytochrome oxidase. The distribution of melanin granules in the retinal pigment epithelium related to the activity of another copper-containing enzyme, tyrosinase was also studied. Stereological methods were applied to obtain quantitative data.
Results:
In the retinal photoreceptor inner segments of the macular mouse, the mitochondria were more numerous than in normal litermates and they appeared swollen. There were fewer melanin granules in the retinal pigment epithelium of macular mice than in that of normal littermates. The cytochrome oxidase activity was significantly lower in the macular mice than in the controls.
Conclusion:
Macular mice have lower activity of cytochrome oxidase and fewer melanin granules than do normal mice. Both changes may be related to copper deficiency. These results correspond to the retinal changes seen in patients with Menkes' disease.
Insights
Macular mice, a model for Menkes' disease, exhibit reduced cytochrome oxidase activity and fewer melanin granules, indicating potential copper deficiency and mirroring human retinal conditions.
Area of Science:
- Ophthalmology
- Neuroscience
- Genetics
Background:
- Menkes' disease is a genetic disorder characterized by copper deficiency, affecting various organs.
- The macular mouse serves as a relevant animal model for studying Menkes' disease.
- Copper is essential for the function of copper-containing enzymes like cytochrome oxidase and tyrosinase.
Purpose of the Study:
- To investigate retinal changes in macular mice, a model for Menkes' disease.
- To examine melanin granule distribution in the retinal pigment epithelium and cytochrome oxidase activity in macular mouse retinas.
- To correlate observed retinal alterations with potential copper deficiency.
Main Methods:
- Cytochemical analysis using diaminobenzidine to detect cytochrome oxidase activity in macular mouse retinas.
- Study of melanin granule distribution in the retinal pigment epithelium, linked to tyrosinase activity.
- Application of stereological methods for quantitative analysis of retinal tissues.
Main Results:
- Macular mice showed significantly lower cytochrome oxidase activity compared to normal littermates.
- A reduction in melanin granules was observed in the retinal pigment epithelium of macular mice.
- Mitochondria in the retinal photoreceptor inner segments of macular mice were more numerous and swollen.
Conclusions:
- Macular mice exhibit decreased cytochrome oxidase activity and fewer melanin granules, consistent with copper deficiency.
- These findings in the macular mouse model correlate with retinal pathology observed in human Menkes' disease patients.
- The study highlights the utility of the macular mouse in understanding the retinal manifestations of copper metabolism disorders.