The vomeronasal system is crucial for social and sexual communication in mammals. Brazilian Institute of the Environment (IBAMA 1-35-93-0848-0). Food (Nutricobaia pellets; Purina) and water were provided (Ctenomyidae, = 3) and (Octodontidae, = 3), both species diurnal and subterranean; and (Octodontidae, = 3) (Vega-Z?iga, 2009) and (Chinchillidae, = 2) (Delano et al. 2010), both species nocturnal and solitary. Capybaras were deeply anaesthetized with an overdose of pentobarbitone (80 mg kg?1, i.v.). The carotid artery and jugular vein were exposed by making a skin incision along the neck, and 100 mL of 0.1 m phosphate-buffered saline (PBS) at pH 7.4 was perfused through a cannula inserted into the left common U0126-EtOH biological activity carotid artery, followed by 500 mL of 4% formaldehyde in PBS. The olfactory bulbs were cautiously dissected out and kept in the same fixative answer until further processing (within 2 months after perfusion). The tissue was then submerged for cryoprotection in a 30% sucrose answer (w/v) in PBS until it sank. We obtained sagittal sections 60 m solid using a sliding microtome U0126-EtOH biological activity (Leitz-Wetzlar 1400; Leitz, Germany) equipped with a freezing stage (BFS-30MP; Physitemp, Clifton, NJ, USA). Every other section was mounted and Nissl-stained with cresyl violet. The remaining sections were utilized for immunohistochemistry as follows: we put them in vials made up of PBS with 0.05% Triton X-100 (PBST) and 0.3% H2O2 for 30 min, followed by 5% normal goat serum (NGS) in PBST for 1 h. We then incubated them in mouse monoclonal antibodies raised against Gi2 (1 : 200, cat no. sc-13534; Santa Cruz Biotechnology) or Go (1 : 200, cat no. sc-13532; Santa Cruz Biotechnology) with 3% NGS in PBST for 18 h at 25 C. Next, the sections were washed in PBS and incubated in biotinylated goat anti-mouse immunoglobulins (1 : 200, cat no. sc-2039; Santa Cruz Biotechnology) for 2 h and processed with avidin-biotin (ABC Elite kit; Vector Laboratories) for 1 h. Finally, the tissue was reacted in PBS with 0.6 mg mL?1 U0126-EtOH biological activity of 3,3-diaminobenzidine (Sigma) and 0.03% H2O2 for 20C120 s. All other caviomorph brain tissue was conserved in 4% paraformaldehyde in PBS until its use (up to 18 months). After cryoprotection in sucrose 30% (w/v), we obtained 40-m sagittal sections and stained them with cresyl violet. The olfactory bulbs of one specimen of were immunolabelled against Gi2 with the same protocols explained above for capybaras, before being counterstained with cresyl violet. We compared morphometric values between the rAOB and cAOB in Nissl-stained sections of capybaras following the same rationale and methods previously used for degus (Surez & Mpodozis, 2009). Briefly, we recorded the area of the AOB in series of nine sagittal 60-m TSPAN3 sections, spaced 120 m each and centred in the slice with the maximum AOB area. We excluded the farthest medial and lateral portions of the AOB because cell layers curve up in U0126-EtOH biological activity the sagittal plane, making it hard to outline the borders between cell layers and subdomains. For each section we measured the area of the overall AOB (from your vomeronasal nerve layer to the lateral olfactory tract) and of the glomerular layer only, in both rAOB and cAOB. We computed volume values by multiplying section areas by their thickness. The volume of the alternated slices was estimated as the average values between the volumes of flanking slices. We also scored, for each section and AOB subdivision, the total quantity of glomeruli, the mean diameter of glomeruli, determined by measuring 10 randomly U0126-EtOH biological activity chosen glomeruli at each subdivision, and the mean quantity of mitral/tufted cells inside a 0.01-mm2 area randomly placed at the.