On the other hand, a decreased cutaneous immune response and increased bactericidal activity was demonstrated after in ovo T treatment in house wrens. The physiological mechanisms underlying the effects of maternal androgens on the immune system of young birds are poorly understood, but several hypotheses have been delineated. According to resource allocation theory, stimulation of energydemanding processes by increased yolk androgen levels should be counterbalanced by lowered immune functions in offspring. However, the results of most studies do not support such a trade-off between androgenmediated effects on growth and immunity, so other explanations should be considered. In birds, the important determinants of early posthatching immune functions are provided by the maternal transfer of immune-competent substances into the eggs such as antibodies, antioxidants and antimicrobial proteins. Both genetic and environmentally-driven differences in maternal transmission of these immune factors have been documented and are predicted to correlate with phenotypic variability in offspring immune responsiveness. Maternally-derived yolk antibodies provide the first humoral immune protection after hatching, when the immune system is not fully developed. Antioxidants in the eggs are considered to be potential inhibitors of oxidative stress, with consequences on immunity and survival of offspring. Maternal antimicrobial immunity is mediated by egg lysozyme, a major antimicrobial protein, which acts through the hydrolysis of Gram-positive bacteria cell walls. Thus, the correlative evolution of different pathways for maternal effects is expected. This is supported by an inverse pattern of yolk T and IgY levels within the laying sequence in the black-headed gull, Larus ridibundus. On the other hand, increased yolk A4 transfer, followed by elevated transfer of maternal antibodies, was reported in the black-legged kittiwake, Rissa tridactyla. Taken together, there are still limited data dealing with the mutually adjusted deposition of different maternally-derived compounds in the egg, and how changes in one substance can be related to changes in others. In the present study, we examined common and different pathways for maternal effects using genetic lines of Japanese quail that were independently selected for yolk T concentrations, the duration of tonic immobility and social reinstatement behaviour. Lines selected for contrasting levels of yolk T, low and high egg T lines, differed also in A4 and estradiol in their eggs. In addition, LET and HET quail ONX-0914 displayed differences in postnatal growth and some aspects of the immune response. The duration of TI is a measure of fear reaction to physical restraint that exists in many species. Selection for TI affected the general reactivity of birds. Birds with the long duration of TI showed increased behavioural inhibition in an open field test, longer latency to enter a new environment during an emergence test and to approach novel food and were more disturbed by the sudden introduction of a frightening stimulus into their home cage as compared to quail with the short duration of TI. Quail selected for high and low SR behaviour differed consistently in their social motivation under various experimental conditions and in several aspects of their social behaviour.