Fig. 1.

Freeze-fractured astrocyte end-feet membranes in suprachiasmic nucleus from adult rat. (A) The conventional replica has a 2-nm-thick platinum coat and a 1- to 2-nm coat of water vapor (27). Multiple square arrays appear as 6-nm P-face IMPs. (B) In higher-resolution replicas made with ≈1 nm of platinum without detectable water vapor, square arrays consist of 4-nm IMPs linked by 1 × 2 nm cross-bridges. (C) In E-face images, 3- to 4-nm pits are linked by 1 × 2 nm furrows. (Insets) Representative examples are enlarged and printed with black shadows. (Bars = 100 nm.)