TABLE I.

Distribution of Cell Phenotypes in C2 Cultures Reacted via Double Immunofluorescence with Antibodies Against MyoD and Myogenin

		Averaged Per Ten Fieldsa
Days in 2% FCS	Growth Factor Added	Total Number of Cells	Number of Cells Fused into Myotubes	Mononucleated Cells Only					Total Number of Cells with Myogenic Phenotypeb
				All MyoD+	All Myog+	MyoD+/Myog−	MyoD+/Myog+	MyoD−/Myog+
1	None PDGF	1049.2 ± 135.2 980.7 ± 103.2	0.5 ± 0.5 0	107.2 ± 14.2 100.7 ± 17.7	28 ± 6 18.5 ± 4	79.2 ± 8.2 82.2 ± 13.7	28 ± 6 18 ± 4.5	0 0.5 ± 0.5	107.7 ± 14.7 100.7 ± 17.7
2	None PDGF	1074.5 ± 73.5 2314.5 ± 224.5	41 ± 29 6 ± 2	191.5 ± 0.5 228.5 ± 2.5	170 ± 6 180 ± 13	75.5 ± 8.5 115.5 ± 6.5	116 ± 9 113 ± 9	54 ± 3 67 ± 4	286.5 ± 26.5 301.5 ± 4.5
3	None PDGF	1224.5 ± 85.5 2932.5 ± 119.5	80.5 ± 20.5 40.5 ± 2.5	276 ± 41 324 ± 24	246 ± 18 275 ± 65	71.5 ± 13.5 139.5 ± 8.5	204.5 ± 27.5 184.5 ± 15.5	41.5 ± 9.5 90.5 ± 47.5	398 ± 1 455 ± 76
4	None PDGF	1292.5 ± 2.5 3468.5 ± 151.5	263.5 ± 15.5 143.5 ± 29.5	139 ± 45 402.5 ± 46.5	178 ± 6 402.5 ± 42.5	58 ± 23 202.5 ± 45.5	81 ± 22 200 ± 1	97 ± 16 202.5 ± 43.5	499.5 ± 13.5 751.5 ± 23.5

^aCultures were initiated at higher cell density in proliferation medium and 24 hours later switched to 2% FCS ( ± PDGF-BB). Results shown for days 2 through 5 under all categories reflect the actual numbers scored for ten microscopic fields which were further averaged for duplicate plates. Scores for day 1 were obtained by analyzing twenty fields per plate and numbers were then averaged per ten fields using results of duplicate plates. Additional fields were analyzed for day 1 in order to more reliably measure the myogenin+ cells which were infrequent in the day 1 plates. Microscopic fields were randomly selected and counted using 40x objective.

^bThe total number of cells with a ‘myogenic phenotype’ is the sum of the number of cells under: MyoD+/myogenin−, MyoD+/myogenin+. MyoD−/myogenin+, and cells fused into myobtubes.