Résumé
Meshed pigmented iris epithelium along with neural retina of tadpoles of the frog Euphlyctis cyanophlyctis were found to undergo dedifferentiation and subsequently transdifferentiate into lens in culture medium. During lag period, depigmentation (dedifferentiation) occurred in many cells. When culture became confluent 3-4 weeks after seeding tiny lens like structures differentiated from foci of cultured pigmented iris epithelium cells. The percentage of lens formation was higher in vitamin A treated cases. The culture system appears to be a suitable for investigating the changes occurred during trans-differentiation of pigmented epithelial cells into lens.
Sujets)
Animaux , Transdifférenciation cellulaire/effets des médicaments et des substances chimiques , Iris/cytologie , Iris/effets des médicaments et des substances chimiques , Larve/cytologie , Larve/croissance et développement , Cristallin/cytologie , Cristallin/effets des médicaments et des substances chimiques , Cristallin/croissance et développement , Épithélium pigmentaire de l'oeil/cytologie , Épithélium pigmentaire de l'oeil/effets des médicaments et des substances chimiques , Ranidae/anatomie et histologie , Ranidae/croissance et développement , Techniques de culture de tissus , Rétinol/pharmacologieRésumé
Emblica officinalis (Amla) accelerated cell proliferation and dedifferentiation of pigmented epithelial cells of dorsal iris and consequently induced lens regeneration in R. cyanophlyctis. Further it enhanced the percentage of lens regeneration not only in young tadpoles but also is adult frogs. Lens regeneration ability declined with the age of animals in both control as well as treated groups.
Sujets)
Vieillissement/effets des médicaments et des substances chimiques , Animaux , Cristallin/effets des médicaments et des substances chimiques , Cristallin/croissance et développement , Phyllanthus emblica/composition chimique , Extraits de plantes/usage thérapeutique , Ranidae , Régénération/effets des médicaments et des substances chimiques , Résultat thérapeutiqueRésumé
Median third eye was found to develop from transplanted pineal gland of external gill stage tadpoles in the recipient 5 toe stage tadpoles of Bufo melanostictus. Pineal gland along with a bit part of brain tissue of the donor external gill stage tadpole was cut out and transplanted into a pit made between two lateral eyes of 5 toe stage recipient tadpoles. Half of the operated tadpoles were treated with vitamin A (15 IU/ml.) for 15 days. Median "third eye" was found to develop in the both untreated and vitamin A treated tadpoles. However, vitamin A increased the percentage of the development of median eyes. Morphological and histological study revealed that newly transformed median eyes were similar to that of normal functional eyes. A stalk like structure developed which connects the median eye to the brain. The median third eye could not develop when pineal gland of 5 toe stage mature tadpole was transplanted into the tadpole of the same age.