One human embryonic stem cell in its colony on a feeder-free matrix, alive: it runs through G1, S, G2 and M at the cited phase lengths. Its size is not measured.
Cell cycle length, the four phases summed
15.5 h 15 to 16 h across the sourced ranges. No sourced capacity for this quantity, so the bar places this cell between the smallest and the largest the sourced ranges allow.
The phases sum to the whole cycle: G1 2.5 to 3 h, S about 8 h, G2 about 4 h, M about 1 h, in H1 and H9 (Becker 2006).
source 1
G1 phase length
2.71 h
2.62 to 2.79 h propagated
S phase length
7.87 h
7.62 to 8.13 h propagated
G2 phase length
3.94 h
3.81 to 4.06 h propagated
M phase length
0.984 h
0.952 to 1.02 h propagated
Withheld
Cell diameter
Source pending: no measured undifferentiated H1 or H9 cell diameter in 11,100 abstracts and 167 full texts, searched 2026-09-14. The stage shows a size that is not measured and labels it.