Forty-micrometer-thick Vibratome sections were collected from the dorsal LA corresponding to coronal planes of Bregma −2.25 to −3.75 mm. To prevent loss of antigenicity due to excess fixation, sections were treated with sodium borohydride (1%, in 0.1 M PB) at the 5th hour following transcardial perfusion. From this step on, brain sections were stored at 4°C, suspended in 0.01 M PB with 0.9% NaCl and 0.05% sodium azide (PBS-azide). Four days later, the Vibratome sections were postfixed with 2% glutaraldehyde for 10 minutes, then processed osmium-free (Phend et al., 1995), dehydrated, infiltrated with 100% EPON (EMBED-812 from EMS), and then placed between two sheets of Aclar plastic and incubated at 60°C overnight (24 hours) to cure the resin. All Vibratome sections were processed in parallel, so as to reduce interanimal and intertissue variability resulting from treatments.
