Improved prolactin crop-sac bioassay applying a morphometric approach.

A pigeon crop-sac bioassay for prolactin was developed applying a morphometric approach for quantification of the epithelial cell proliferation induced by the hormone. A small male dove, indigenous from South America (Zenaida auriculata) previously castrated was used as experimental animal. The total dose of prolactin was divided into 4 daily injections administered systemically into the pectoral muscles. The number of the proliferated cell layers used as the bioassay end point was analyzed statistically. This procedure yields a highly sensitive bioassay with an excellent precision index, particularly well suited for quantification of the different molecular forms of pituitary PRL.