MORPHOMETRIC CHARACTERISTICS OF CRYOPRESERVED MESENCEPHALIC DOPAMINE NEURONS IN CULTURE

Blocks of embryonic rat mesencephalon were freeze-stored for 1-2 years in liquid nitrogen at -196 degrees C with 7.5% dimethyl sulfoxide (DM SO) as cryoprotectant. After thawing, pooled mesencephalic tissues wer e mechanically dissociated. The cells, plated at two different densiti es (4.10(5) and 2.10(5)/cm(2)) were cultured in a serum-supplemented m edium for at least 2 weeks before immunocytochemical staining with hig hly specific antidopamine (DA) antibodies. The cryopreserved DA-immuno reactive (IR) neurons were compared, by means of computerized morphome try, to the fresh ones plated at the same densities. A separate analys is of the dendritic and axonal morphometric parameters revealed that t he cryopreserved DA-IR cells, whatever the experimental conditions, ha d significantly larger dendritic fields and, less significantly, large r axonal fields than their fresh counterparts. A principal component a nalysis, mainly based on the dendritic morphometric parameters, allowe d to individualize only two populations (cryopreserved and fresh) amon g the four,stoups studied. These findings underline the role of dendri tes as potential sites of release and/or re-uptake of dopamine and the ir possible implications in functionally effective cryopreserved nigra l grafts. (C) 1997 Elsevier Science B.V.