Uranyl-EDTA-hematoxylin: a new selective staining technique for nucleolar material

Area of Science:

• Cell Biology
• Molecular Biology
• Histology

Background:

• Nuclear structures like bands, Balbiani rings, and nucleoli are crucial for cellular function.
• Effective visualization techniques are essential for studying these structures.

Purpose of the Study:

• To develop a selective staining method for visualizing nuclear structures.
• To identify the components within nucleoli responsible for retaining specific stains.

Main Methods:

• Utilized glutaraldehyde fixation and acetic acid flattening for sample preparation.
• Employed uranyl mordanting followed by hematoxylin staining.
• Applied ethylenediaminetetraacetic acid (EDTA) extraction at varying durations post-mordanting.

Main Results:

• Uranyl mordanting and hematoxylin staining visualized all nuclear structures.
• EDTA treatment selectively inhibited hematoxylin staining in all structures except the nucleolus.
• Extended EDTA extraction (60-90 sec) revealed preferential uranyl ion retention in the nucleolar pars fibrosa.

Conclusions:

• The developed method allows for selective visualization of nucleolar material.
• The pars fibrosa region of the nucleolus demonstrates a high affinity for uranyl ions, suggesting a proteinic composition.
• This technique is effective across different cell types, including Chironomus salivary glands, Drosophila testes, and Allium roots.