A cystic follicle is one that has failed to ovulate after reaching maturity. The egg is retained inside the follicle and fertilization cannot occur. The CL does not form and the cycle does not proceed. The exact cause of this failure is unknown. While follicular development and ovulation are under the control of FSH and LH from the pituitary, these events can be modified by injection of hormones.
Cattle generally ovulate one egg during each cycle.
This provides the basis for superovulation where several eggs may be obtained following injection of PMSG at the correct time of the cycle. However, the response to superovulation treatments varies widely between animals. While some animals produce few eggs others are overstimulated and the ovaries become extremely large. The upper end of the oviduct is funnel shaped. It is here, in the upper part of the oviduct, that fertilization takes place.