Fig. 5.

HSP27 expression correlates with survival after NGF withdrawal in vitro. Dissociated cultures from P0 lumbar DRG were cultured for 48 hr in the presence (d) or absence (a–c) of NGF.a–c, The same field is shown, immunostained for PGP9.5 to identify neurons (a), HSP27 (b), or Hoechst 33342 to visualize nuclear morphology (c). After 48 hr without NGF, neurons that expressed HSP27 had round healthy nuclei (arrows ina–c), whereas the majority of those that were negative for HSP27 immunoreactivity had pyknotic nuclei (arrowheads in a–c). e, The percentage of HSP27-immunopositive neurons with pyknotic nuclei was counted, and the same was done for HSP27-immunonegative neurons. Data shown are means ± SD from four independent experiments; a total of 5533 neurons were counted. d, In the presence of NGF, HSP27 was not necessary for either survival or neurite outgrowth (darkcells are HSP27 positive). Scale bars, 50 μm.