The slices were deparaffinated and hydrated before
stained with hematoxylin for 10 min, flushed with water
till no color could be washed off; nextly they were differentiated
with hydrochloric acid alcohol, turned blue in tap
water, incubated in eosin for 1min, and then dehydrated
with alcohol, cleared with xylene, and sealed with neutral
gum. At least 10 stained slices were randomly selected
from each group. Microscope camera system (Olympus
BX41, Japan) was adopted to observe the slices and take
photos for them. The number of corpora lutea or corpora
albicantes was recorded under a 10× objective lens. The
diameter of follicles (in the cross-section containing the
oocyte nucleolus), the thickness of the cortex and medulla
were measured using an ocular micrometer.