Distribution of prolactin receptor in frog (Rana ridibunda) dorsal skin during hibernation.

The role of prolactin in the regulation of frog skin functions is still unclear particularly during environmental changes. In this study, prolactin receptor (PRLR) was detected in active and hibernating frog dorsal skin using immunohistochemical method. PRLR immunoreactivity in active frogs was observed in the epidermis, in the secretory epithelium of granular glands and the secretory channel cells of the glands. Myoepithelial cells of granular glands that started accumulating secretory material or those with a full lumen were PRLR immunoreactive, while some myoepithelial cells of empty granular glands were negative for PRLR. In hibernating frogs, this immunoreactivity was observed in the same regions; however, immunoreactivity was more intense than that in active frogs. PCNA was employed for detection of proliferative activity of PRL in the dorsal skin, and immunoreactivity was detected in the nuclei of a few epidermis cells and in the duct of glands of active frogs. The number of immunoreactive nuclei in these regions increased in hibernating and in prolactin injected groups. We conclude that prolactin provides morphological and functional integrity of skin stimulating the proliferation and regulating the function of granular glands and plays an important role in the adaptation of amphibians to the long winter period.

Kestel: an early bronze age source of tin ore in the taurus mountains, Turkey.

An ancient mine located at Kestel on the outskirts of Nigde, in the Taurus Mountains of south central Turkey, has been dated by radiocarbon and pottery type to the third millennium B.C. Archeological soundings in the mine located cassiterite (tin oxide) in the detritus of ancient mining activity. Cassiterite is also present in veins and, as placer deposits, in streams nearby. Since tin is used with copper in order to form bronze but is thinly distributed in the earth's crust, the presence of tin ore at Kestel offers a source for the much sought after tin of the Bronze Age. The discovery of an ancient mine containing cassiterite sheds light on this question, but also greatly complicates the accepted picture of regional economic patterns in the highland resource areas of Anatolia and of interregional metal exchange in the formative periods of urbanization and metal use in the eastern Mediterranean.