CALBINDIN D-28K AND PARVALBUMIN EXPRESSION IN MITOTIC CELLS OF RAT PRIMARY CORTICAL CULTURES

CALBINDIN D-28k and parvalbumin expression was studied immunocytochemi cally in monolayer mixed cortical cultures from rats aged 16 (E16), 17 (E17), and 19 (E19) days of gestation using monoclonal antibodies and the avidin-biotin immunoperoxidase method. Whereas in vivo both calci um-binding proteins are exclusively expressed in postmitotic neuronal populations, they were demonstrated in mitotic cultured cells at the t hree fetal ages and the three maturation times considered (6, 12, and 15 days). A subpopulation of immunostained mitotic cells was identifie d as astroglial cells after a double labelling study using an antibody against glial fibrillary acidic protein. These results suggest that c onditions in vitro may induce the expression of calbindin D-28k and pa rvalbumin in mitotic cells.