CELL-CYCLE TIME OF MURINE NEOPALLIAL CELLS IN-VITRO

Disaggregated glial cells from newborn CD1 mouse neopallia were cultur ed in low concentration (4.2 x 10(3) cells/cm(2)) for 72 hr and then e ither pulse labeled with BrdU by one 2-hr pulse at various times of cu lturing or continuously labeled for various lengths of time, At the en d of incubation, the cells were fixed and immunoreacted with BrdU, All BrdU(+) and BrdU(-) cell nuclei were counted in an area of 4.84 cm(2) , A three-compartment model for interpretation of the experimental dat a was developed consisting of active proliferating cells, non-active c ells with proliferating potential, and nonproliferating cells, The mod el is based on assumptions of time invariance of culture conditions, r andom re-entry of cells into cell cycle and random exit from the proli ferating pool, Furthermore, it is assumed that average values are repr esentative for describing the numbers of cells in specific compartment s as functions of time, A set of relationships representing the number s of labeled cells for pulse labeling and continuous labeling assays i s derived from these assumptions and the generally accepted representa tion of cell progress through the cell cycle, i.e., a genetically pred etermined sequence of post-mitosis rest phase, S-phase, pre-mitosis re st phase, and mitosis, These relationships are used to evaluate the S- phase time tau(S) and cell cycle time tau(c) of proliferating cells, U nder our particular conditions, we obtain approximately tau(S) = 8 hr and tau(c) = 16 hr, respectively, The applicability of the model and p ossible distorting factors are discussed. (C) 1996 Wiley-Liss, Inc.