Location of DNA within the nucleolus of rat oocytes during the early stages of follicular growth.

We have investigated the DNA distribution within the rat oocyte nucleolus during the early stages of follicular growth by means of the in situ terminal deoxynucleotidyl transferase method. In the fibrillogranular nucleolus, label is visualized on small clumps of peri- and intranucleolar chromatin. Such labeled clumps are frequently observed inside the interstices surrounding the fibrillar centers. Label is also consistently found in the fibrillar centers whereas the dense fibrillar component and the granular component are devoid of gold particles. These results contradict earlier data but conform with other recent immunocytochemical observations, obtained in nucleoli of a variety of somatic cell types, concerning the correlation between structure and function in the nucleolus.