DEVELOPMENT OF AN HOMOLOGOUS RADIOIMMUNOASSAY FOR CHICKEN FOLLICLE-STIMULATING-HORMONE AND MEASUREMENT OF PLASMA FSH DURING THE OVULATORY CYCLE

1. A highly specific and sensitive homologous radioimmunoassay was dev eloped for measurement of chicken follicle stimulating hormone (cFSH). 2. Mammalian gonadotropin releasing hormone (GnRH) significantly stim ulated secretion of chicken luteinising hormone (cLH) but not cFSH whe n administered to 22 week non-laying hens. 3. Chicken GnRH-1 did not a ffect circulating cFSH concentrations but significantly stimulated cLH secretion when administered to 3 week cockerels. 4. The plasma concen tration of cFSH was low throughout the ovulatory cycle, but a signific ant decline in cFSH occurred prior to the pre-ovulatory LH surge and a significant increase occurred during the 3 hr prior to oviposition as LH levels decline.