THE EFFECT OF AGE AND SEX ON THE EXPRESSION OF PROLACTIN BINDING-ACTIVITY IN THE CHICKEN BURSA OF FABRICIUS

The binding of I-125-labeled prolactin (PRL) to membranes from the bur sa of Fabricius of male and female chicks of different ages (15-30-45 and 60 days) was studied. In male chicks the binding was very low in 1 5 day-old animals and slightly increased in more aged animals. In fema le chicks the binding was more evident in young animals and decreased in 60 day-old animals. The binding showed a hormonal specificity and S catchard analysis of the binding revealed the presence of binding site s with low capacity and high affinity. The presence of PRL receptors i n the bursa of the chick, a structure that confers immunological compe tence to birds, gives further support to the involvement of the hormon e in the immune processes.