ABSTRACT
The avian ovary represents a truly dynamic organ system capable of fostering the annual development of one or more broods of viable eggs, then undergoing nearly complete regression followed by eventual recrudescence (see also Chapter 4 and Volume 6B, Chapter 13). The seasonal initiation of ovarian recrudesence may be driven by endogenous circannual rhythmicity and synchronized by environmental cues, the most important of which is photoperiod and to a more limited extent, light intensity (Gwinner 2003). Such cues are translated into neuroendocrine and endocrine signals, the primary factors being hypothalamic gonadotropin releasing hormone (GnRH) and pituitary gonadotropins, respectively. Subsequent events, which include nesting, follicle maturation and ovulation, are generally initiated by factors other than light (e.g., rainfall, temperature, food availability, male behaviors).
