The haemoglobin in the condensed chromatin of mature amphibian erythrocytes: a further study.

The condensed chromatin in mature nucleated erythrocytes is surrounded by nuclear haemoglobin at a concentration about equal to that in the cytoplasm. New measurements employing improved fixation, glutaraldehyde instead of OsO4, and microspectrophotometnc analyses instead of photographic photometry at one wavelength, show that previously reported values for the content of haemoglobin in the mass of the chromatin in Triturus crutatus, 45-50%, were far too high. In the condensed chromatin of 3 species of amphibia the concentrations of intrachromatin haemoglobin relative to the cytoplasm are 10% (Triturus crutatus), 10% (Necturus maculosa) and 8 % (Amphtuma trtdactylum). It is concluded that haemoglobin is only a minor component of chromatin, and this result is discussed in relation to the condensation of erythrocyte chromatin and observations on its ultrastructure.