SHORT DAY INDUCED GONADAL REGRESSION IN RING DOVES (STREPTOPELLA-RISORIA) - A CASE FOR SEASONAL-VARIATION

  • 1 January 1980
    • journal article
    • research article
    • Vol. 7  (3) , 357-370
Abstract
Changes in follicular size (in diameter) were studied by laparotomy under various photoperiodic regimes in the domesticated ring doves that were kept under standard laboratory conditions for generations. Follicular response shows 2 distinct patterns: a shift from standard laboratory photoperiodic regime (LD [light-dark] 14:10) to extra long day (LD 20:4) accelerated the follicular development in the spring and in the autumn; 2, a shift from the standard laboratory photoperiodic regime (LD 14:10) to short day (LD 8:16 or LD 1/2:23 1/2) induced follicular regressions in the autumn but not in the spring. There may be a responsive phase (spring) and nonresponsive phase (autumn) of hypothalamo hypophyseal ovarian system in the ring doves. Comparison of radioimmunoassay of pituitary and plasma LH [luteinizing hormone] value suggests that the responsive and non-responsive phase involves mainly release mechanisms. In the autumn, the release mechanism becomes insensitive to stimuli below certain thresholds. The ring doves are kept in responsive pahse throughout the year under the long photoperiodicity (LD 14:10). The effect of long day dose not appear to override completely the seasonal effect.