Ultrasound biomicroscopy in the diagnosis of persistent hypotony after vitrectomy.

PURPOSE: To describe a case of persistent hypotony after an otherwise successful vitreous surgery for epiretinal membrane, in which ciliochoroidal detachment was detected by ultrasound biomicroscopy but not by ophthalmoscopy. METHOD: We used ultrasound biomicroscopy to determine the cause of persistent postoperative hypotony. RESULTS: Ultrasound biomicroscopy clearly disclosed ciliochoroidal detachment. In an attempt to resolve ciliochoroidal detachment, we performed vitrectomy and fluid-gas exchange combined with diathermy around the sites of sclerotomy. Postoperatively, the regression of ciliochoroidal detachment was confirmed by ultrasound biomicroscopy. CONCLUSIONS: Using ultrasound biomicroscopy, we were able to visualize ciliochoroidal detachment and its regression clearly, which we had not observed during ophthalmoscopy.

Plasticity and rigidity of differentiation of brain vesicles studied in quail-chick chimeras.

Transplantation of a piece of the alar plate of the prosencephalon or of the rhombencephalon of quail embryos into the roof of the mesencephalon of chick embryos was carried out at 7-10 somite stage. Results obtained were: the transplanted alar plate of the prosencephalon differentiated into tissue closely resembling the tectum when the transplants were integrated into the host mesencephalon; in all the cases, the alar plate of the rhombencephalon did not differentiate into tectum-like structure, but into rhombencephalic descendants. We conclude that the alar plate of the prosencephalon at 7-10 stage is not definitively determined and may retain an ability to differentiate into the optic tectum, whereas the prospective fate of the rhombencephalon has already been determined at 7-10 stage.

Origin of the irideal striated muscle in birds.

The aim of the present study was to elucidate the origin of the striated muscle cells in the avian iris. For this purpose we adopted interspecific transplantation between quail and chick embryos because quail cells can be used as biological markers in this system. We transplanted isotopically and isochronically (6- to 7-somite stage) a fragment of a dorsal part of the quail neural anlage into a chick embryo at the level corresponding to the posterior prosencephalon and the mesencephalon on the right-hand side. In the chimaeric embryo, the iris epithelium comprised host chick cells, while most of the stromal cells of the iris on the operated side possessed the quail nuclear marker. At 19 days after the operation, the striated muscle cells had differentiated in the chimaeric embryo. These cells, as well as connective tissue cells and the Schwann cells of the iris of the chimaera, were shown to possess typical quail nuclei by light and transmission electron microscopy. From these findings, we conclude that the striated muscle cells originate from the neural crest.