Antibody:	anti-Mash1
Detection system:	Secondary antibody coupled to Alexa Fluor 488

Structure	Level	Pattern	Image	Note
TS20: cerebral cortex ventricular layer	Present		1K	Many positive nuclei expressed Neurog1 (39.9%).

Structure	Level	Pattern	Image	Note
TS20: cerebral cortex ventricular layer	Present		1L	Many positive nuclei expressed Neurog2 (33.9%).

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex ventricular layer	Present	Regionally restricted	1M	Nonoverlapping expression domains with Neurog2. The level of coexpression (19.7%) dropped substantially at E15.5 as compared with E12.5.
TS23: cerebral cortex subventricular zone	Present		1M	The level of coexpression (34.6%) remained slightly higher.

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex ventricular layer	Present	Regionally restricted	1N	Nonoverlapping expression domains with Neurog2. Expressed mostly near the ventricular surface and at the ventricular zone/subventricular zone border.
TS23: cerebral cortex subventricular zone	Present		1N	The level of coexpression (34.6%) remained slightly higher.

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex subventricular zone	Present		1O	The level of coexpression (34.6%) remained slightly higher.
TS23: cerebral cortex ventricular layer	Present	Regionally restricted	1O	Nonoverlapping expression domains with Neurog2. Expressed mostly near the ventricular surface and at the ventricular zone/subventricular zone border.

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex ventricular layer	Present		2E	The percentage of positive nuclei also labeled by BrdU was not significantly different from the ratio expected for a random cell-cycle distribution.

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex ventricular layer	Present		2F	More positive cells were colabeled with BrdU (61.4%) than expected from a random cell-cycle distribution (46.7%).

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex ventricular layer	Present		2G	A trend toward fewer positive cells labeled with BrdU than would be expected if indiscriminately expressed throughout the cell cycle.

Structure	Level	Pattern	Image	Note
TS23: cerebral cortex ventricular layer	Present		2H	Expressed in some pHH3+ nuclei, consistent with the idea that it was not excluded from G2/M-phase of the cell cycle.