Figure 2.

Proliferation and senescence in the subependymal zone (SEZ). (A,B) High magnification photographs of domains of the SEZ (dorsal in A, middle in B) taken from young adult mouse brain tissue immunostained for PCNA (to mark proliferating cells) and laminin (to mark blood vessels, BVs). Note the existence of multiple proliferating cells around the long BV running in parallel to the lateral ventricle in (B), but also the existence of high proliferative activity in areas distant from BVs in (A). (C–E) High magnification photographs of domains of the SEZ (middle in C,D and ventral in E) taken from young (in C,E) and aged (in D) rat brain tissue immunostained for laminin and chemically stained for senescence-associated β gal (in blue). Arrowheads indicate BVs and arrows senescent cells. Note the significantly lower density of BVs at the non-neurogenic side of the lateral ventricle (at the left of C), the existence of senescent cells along BVs outside the SEZ and the existence of high numbers of senescent cells in the ventral domain of the young-adult rat SEZ (in E). (F) High magnification of adult mouse NSCs isolated from the SEZ and kept in culture. Note the existence of senescent cells (nuclei are counterstained with nuclear fast red). [Antibodies used: rabbit anti-laminin: 1/500 (Abcam), mouse anti-PCNA: 1/500 (Abcam). Alexa goat anti-rabbit 568 and goat anti-mouse 488 (Invitrogen). Biotinylated goat anti-rabbit and DAB staining kit (Vector laboratories). Senescence-associated β gal staining kit (Millipore). Adult NSCs cultured in DMEM/F12 supplemented with B27 (Gibco), FGF2 (20 ng/ml) and EGF (20 ng/ml). All animal work was performed in accordance with the UK Animals (Scientific Procedures) Act 1986 and was approved by the University of Cambridge Animal Welfare and Ethical Review Body].