Immunolocalization of nucleolar markers in embryonic and adult nuclei.

<p>A, B) In the adult gonad, prominent nucleoli are easily detected in all nuclei (arrows), except in those of the most mature oocytes. Accordingly, only a faint nucleoplasmic DAO-5 signal (in red) can be detected in these late oocytes (arrowhead). C, D) At the 2-cell stage, the DAO-5 and FIB-1 antibodies label numerous dots of varying size and intensity throughout the nucleoplasm. E,F) The first appearance of distinct nucleoli (arrows) occurs at the 6- to 8-cell stage. Shown here are projections of parts of 8-cell embryos. G) At later stages, all somatic cells display one, or in most cases two DAO-5-labeled nucleoli. Shown here is a 2.5 µm slice from a 45-cell embryo. H) On this single optical section of adult intestinal nuclei, DAO-5 is clearly found in ring-like structures in a DNA-poor region. On a projection of all optical sections, numerous dot-like DAO-5-positive structures are seen throughout the nucleoplasm (inset). In this and other figures, the contour of the labeled embryos is dotted and DNA is counterstained with DAPI (in blue). Bars: 5 µm.