Nuclear compactness as assessed by ferrtin permeation: A critical evaluation of the method

The fracture-permeation method was applied in order to assess changes in nuclear compactness associated with different metabolic conditions. Rat ventral prostate was used as a model because transcription in the secretory cells of this organ is highly dependent on androgens. Two major problems that raise important questions concerning the validity of the method were encountered: (1) poorly preserved cells are massively permeated by ferritin and (2) within the same experimental group the permeation pattern was quite variable. In order to objectify such variability, the percentage of permeated nuclear cross-fractures was quantified. Different permeation patterns could be detected in nuclei from normal, castrated, and testosterone-treated prostatic cells, possibly reflecting changes in chromatin compactness.