Autosandri 815

Proximal umbilical cord samples were fixed in paraformaldehyde (2%)-glutaraldehyde (2,5%) cacodylate buffer solution (0.1 M; pH 7.2) for 24 h, washed with cacodylate buffer, postfixed in a solution of 2.5% potassium ferrocyanide for 1 h, and washed again in cacodylate buffer and ultrapure water. Stereomicroscopy was used to obtain longitudinal sections of vessels from the umbilical cord samples. Sections were dehydrated in ascending grades of ethanol, subjected to critical point drying in CO₂ (Autosandri-815, Tousimis), coated with 10 nm of pure gold in a vacuum sputter coater (Desk V, Denton Vacuum) and studied in a direct mode using a scanning electron microscope (Jeol, JEM6610 LV).

Kidney samples from different groups were fixed in paraformaldehyde (2%)-glutaraldehyde (2,5%) cacodylate buffer solution (0.1 M; pH 7.2) for 24 h, washed with cacodylate buffer, postfixed in a solution of 1.25% potassium ferrocyanide for 1 h at room temperature and washed again in cacodylate (0.1 M) buffer and ultrapure water. Longitudinal sections from kidney samples were infiltrated with glycerol solutions (rising from 15% to 30% over 5 minute intervals) to prevent the formation of ice crystals in the sample. After 3 h in glycerol (30%)-cacodylate (0.1 M) buffer solution, the samples were frozen to -80°C and fractured using cooled tweezers. Fractured samples of kidney were washed in cacodylate buffer and ultrapure water and dehydrated in ascending grades of ethanol, subjected to critical point drying in CO₂ (Autosandri-815, Tousimis), coated with 10 nm of pure gold in a vacuum sputter coater (Desk V, Denton Vacuum) and studied using a scanning electron microscope (Jeol, JEM6610 LV) in direct mode.