Morphological analysis and immunohistochemical determination of vitellogenin (Vtg) were carried out in zebrafish ovaries (Danio rerio). The goal was to determine the nutraceutical effect of Spirulina feed on ovarian maturation stages of adult zebrafish. After 30 d, in the stages of advanced maturation a prevalence of oocytes was found in the experimental group. Immunohistochemical investigations revealed a significant increase in Vtg, precursor of vitelline (Vn) in egg yolk, whose expression increased in the liver in relation to the stages of maturation. In the zebrafish liver, the expression of Vtg was extremely low before vitellogenesis, and then increased and it was maintained at a high level until the final stage of ovarian maturation. The results showed that food additives such as Spirulina can improve fertility in laboratory farmed fish. The data obtained from this study may be a contribution to wider research aimed at improving reproduction in all vertebrates, including humans.
Keywords: Spirulina; Zebrafish; morphological and immunohistochemical analysis; oogenesis.