Ontogeny of the photosexual response in intact and castrated coturnix

This study examined the posthatch development of the photosexual response in intact and castrated coturnix. Two criteria were used to determine the onset of the effects of light: (1) the ability to distinguish between long and short photoperiods; and (2) the first increase in serum LH concentration. The results indicated that the onset of the photosexual reflex occurred between 3 and 4 weeks of age in females and between 17 and 21 days of age in males. The immature testes was shown to be involved in the developmental process of the photosexual reflex.