Although the ovality index may be an indicator of stereoscopically obvious horizontal disc tilt, horizontal tilt is more closely related with myopia.

Using 32-cell Xenopus embryos series of extirpation experiments were performed in order to clarify whether or not the dorsal equatorial blastomeres were committed to differentiate to the axial mesodermal structures. First, these blastomeres designated as B1, Bl', Cl and C1' were labeled using the technique of HRP injection or vital staining. They produce descendants which become localized in the organizer region of the early gastrula. These cells form the prechordal plate, notochord, somites, pharyngeal endoderm and neural tube at early neurula stage. The results of extirpation of the medial two or four of these blastomeres show that the entire head lacks or the tissues and organs of the head greatly reduce. This indicates that already at the 32-cell stage they have been committed to autonomously differentiate to form the axial mesodermal tissues of the head and that their roles in the head formation can neither be replaced nor complemented by any other blastomeres surrounding them. It is also shown that the vegetal yolk cells do not seem to play essential roles for development of the axial organs of the head. On the basis of the present results a view of establishment of the organizer of Xenopus eggs is proposed.Since discovery of the organizer by SPEMANN and MANGOLD (1) it has been well established that in amphibians the basic body plan is set up by its peculiar capabilities to autonomously differentiate to the axial mesodermal structures and to induce the neural tissues from the ectoderm. As to anuran Xenopus existence of the organizer is confirmed by SMITH and SLACK (2) who demonstrated formation of the secondary embryo after transplantation of the group of cells from the dorsal marginal zone of an early gastrula to the ventral marginal zone of another embryo.Using explantation techniques NAKAMURA and his cowokers (3, 4) showed that in Xenopus the characteristic features of the organizer are acquired during cleavage stages. In 1970 they reported that the blastomeres localized in the dorsal equatorial region of the 32-cell embryo did not show the self-differentiation ability to form the axial mesodermal tissues but acquired it a little later, at and after the 48-cell stage (3). In 1975 we ( 5 ) repeated the similar explantation experiment using an improved culture technique and found that the mid-dorsal equatorial blastomeres of the 32-cell embryo could autonomously form the notochord and muscle at a high percentage of 75% and 69% respectively. Recently GIMLICH (6, 7) demonstrated in the rescue experiment that the dorsal equatorial cells of the 32-cell embryo could cause partial or complete axis development when they were transplanted to the ultraviolet irradiated recipients which could not form themselves any axial structures. The results of these experiments strongly suggest that the cells situated in the dorsal equatorial 141

No abstract

These results suggest that noradrenaline and forskolin evoked an elevation in [Ca(2+)](cyto) followed by [Ca(2+)](mito), in which H(+) gradient across the inner membrane is responsible for the accumulation of calcium on mitochondria. Moreover, cAMP also plays a role in intracellular and mitochondrial Ca(2+) signalling in cold-acclimated brown adipocytes.