Thus, chronic cytokine release due to recurrent parasite infection may result in retarded development of secondary sex characters.
More recently, we have taken blood samples from captive male and female jungle fowl at monthly intervals from 4 to 8 mo as well as from adults aged 1-2 yr in an attempt to understand the relationship among blood characteristics, secondary sex characters, and mate choice.
Secondary sex characters are correlated with some of these blood parameters.
These scores were then used as the dependent variable in multiple regressions, with sets of the male secondary sex characters and blood cell parameters as independent variables.
Overexpression of male secondary sex characters has also been found in eels (Anguilla rostrata) (16) and white suckers (Catosomus commersoni) (12) exposed to paper/pulp mill effluents.
However, the possibly related effects of pulp and paper mills on male secondary sex characters in different fish species have been identified repeatedly at several times and locations (12,14-17)
Female mosquitofish in the Fenholloway River display male secondary sex characters (35,36).
Both primary and secondary sex characters can be affected by androgen treatment in poceilids, but the lack of understanding of the detailed mechanisms involved is presently preventing a full interpretation of these results.