markers of vitellogenesis¹

Exposure to estrogen induces vitellogenin expression in the liver. The resulting high mRNA levels in hepatocytes produce condition-dependent basophilic staining with H&E. The level of basophilia can be expressed as a mean (reversed) hue value of a representative area.
After its production in the liver, vitellogenin is delivered to the circulation. It can be measured by a specific ELISA, or detected with immunohistochemistry. Immunostaining intensity can be expressed as mean intensity level of a selected area, preferably of a standardised serum compartment; the microphotographs show condition-dependent vitellogenin immunostaining of the serum in the heart.
Liver hue and serum immunostaining intensity both correlate well to ELISA values (R²=0.88 and R²=0.65, respectively, for this particular set of values).

Reference

1. Van der Ven-LT, Holbech-H, Fenske-M, Van den Brandhof-EJ, Gielis Proper-FK, Wester-PW. Vitellogenin expression in zebrafish Danio rerio: evaluation by histochemistry, immunohistochemistry, and in situ mRNA hybridisation. Aquat Toxicol 2003;65:1-11.