Figure 1.

Schematic diagrams of experimental protocols. In experiment 1, rats were injected with Blank-SAP or NK₃-SAP (d 0), and daily vaginal smears were started on experimental day 7 and conducted until ovariectomy (shown at d 30 in this example). In experiment 2, rats were implanted with an E₂ capsule 7 days after ovariectomy, and on the morning of day 9, they were implanted with a P capsule to induce an afternoon LH surge. Rats were killed at the expected time of peak LH levels (shown here at 4 pm), and the brains were harvested for immunohistochemistry.