Fig. 2.

In vivo labeling of PNNs proves to be stable, while enabling monitoring degradation and de novo synthesis of PNNs. (a) Longitudinal imaging of the same PNNs labeled with WFA-FITC over a period of 35 days. No loss of signal was detected. (b) In vivo injection of WFA-Alexa594 stained PNNs specifically and was stable for at least 60 days following injection. (c) Timeline for in vivo monitoring of degradation and de novo synthesis of PNNs. (d) A sketch representing the window and cannula preparation for multiple intracranial injections. (e) Longitudinal imaging with multiple injections of WFA-FITC and chABC allowed monitoring the enzymatic destruction process of the PNNs and their reconstruction. “Day ($X$)” indicates the time relative to chABC injection. Red arrowheads point to PNNs that underwent degradation and yellow arrowheads point to newly formed PNNs. Images represent a $30\text{-}\mu \mathrm{m}$ maximum intensity $z$ projection. Scale bars are $50\mu \mathrm{m}$.