[Preliminary studies on chromatin subunits by freeze-etching].

: We show that freeze-etching electron microscopy preserves and visualizes chromatin structure at level 25 A. Chromatin depleted of histone H 1 is observed to consist of subunits each having a central asymmetric core of DNA and protein 100 by 120 A. Around this core is wound a loop of DNA containing about 130 base pairs and perhaps some protein.