Relationship between clustering of post-ovulatory and hierarchical follicles and their order of ovulation in the mature domestic hen (Gallus gallus domesticus)

Hierarchical (> 8 mm) and post-ovulatory follicles from the ovaries of laying hens at 45 and 86 weeks of age were assigned to clusters defined by the coalescence of their follicular stalks. They were also classified by size to give the succession in which ovulation had occurred, or would occur for the hierarchical follicles. The association between the order of ovulation and the observed clusters was compared with randomness and with dependence on the cluster in which the immediately preceding ovulation occurred. The order of ovulation was associated randomly with clusters, and was independent of the cluster containing the preceding ovulation. Many perceived clusters of successive follicles and post-ovulatory follicles may be compatible with a random order of ovulation. These findings do not support theories of stimulation or inhibition of adjacent follicles, leading to eventual ovulation, by a dominant follicle.