Table 4-3. PRINCIPLES OF STEROID FEEDBACK IN SPONTANEOUS OVULATORS

			Low P4/Low E2		Low P4/High E2		High P4

Phase of the cycle:		early follicular		late follicular		luteal
Surge center (POA):		not activated		activated			suppressed
Tonic center (ARC):		activated			activated			suppressed
Pituitary GnRH receptors:	low			high			diminished
Production of GnRH:	increasing tonic		surge			low tonic