Recent LAMMA studies of physiological cation distributions in retina tissues.

In shock frozen and freeze dried specimens of cat and frog retina distribution patterns of physiological cations were obtained by means of laser microprobe mass analysis with special emphasis to Ca and Ba in structural elements such as photoreceptors and melanin granules. Ca was found to be distributed along single cones of frog in a characteristic bimodal fashion whereas Na and K showed a rather homogeneous concentration profil. The presence of large amounts of Ba in pigment granula was reconfirmed in retina pigment epithelium and, newly, in melanoma cells. Additional microchemical characterization concerned organic constituents of various tissue layers of the retina.