The developmental effect of calcitonin on the interocular distance in early Xenopus embryos.

Treatment of early Xenopus embryos with calcitonin produces synophthalmia by the fifth day of development. In all except the highest dose, the normal interocular distance is acquired by the seventh day and, in the latter group, by the fourteenth day. Because calcitonin is a hypocalcaemic hormone known to inhibit the ruffled borders of osteoclasts in culture, it may interfere with the cell movements of gastrulation, possibly by affecting an ion pump, or the transport of cations across cellular membranes, because the role of calcium ions in cell aggregation and disaggregation has been known for a long time. Alteration of the normal cell movements of gastrulation may result in faulty induction of the overlying neural plate and, in consequent, synophthalmia. Re-assertion of the normal interocular distance by the end of the experiment may indicate that this feature is almost entirely under genetic control and is very little influenced, except in the earliest stages of development, by environmental conditions.