Environmental factors such as temperature and photoperiod changes will stimulate follicle development in female boids. Follicle maturation into fully developed ova and their subsequent release into the oviducts is usually initiated by courtship and the following copulation as most snakes are considered induced ovulators. The female will absorb immature follicles that do not develop into mature ova due to lack of courtship by a male. Fully developed ova that are not fertilized for some reason cannot be absorbed and are released later by the female as unfertilized ova or “slugs”.

Kelly