@entity977 were induced in female @entity35 of @entity35 strain by administration of @entity2691 (E2) and the effect of @entity172 withdrawal on E2-induced @entity5 were studied to elucidate the nature of the induced @entity5 . Ten mg of E2 was administered to 100 @entity35 intraperitoneally once every 2 weeks, totally four times. Experimental animals were sacrificed at 1 week before, 2, 6, 10, and 14 weeks after stopping injection of E2. The incidence of @entity977 and @entity1373 (Table 1). Pituitary glands in each animals were examined and were classified into three groups, namely @entity977 , @entity1373 , and normal gland according to histological findings. The incidence of @entity977 was highest in @entity35 sacrificed 6 weeks after E2 withdrawal. @entity977 became less frequent and @entity1373 and normal glands became more frequent in @entity35 sacrificed thereafter. Pituitary weight (Table 2, Fig. 1) Irrespective of timing of sacrifice, the weight of pituitary gland (mean +/- SE) was 134 +/- 70 mg in the group which were judged as having a @entity977 , 38 +/- 17 mg in the @entity1373 group, and 17 +/- 5 mg in the normal group, respectively. Pituitary weight of control @entity35 were 12 +/- 3 mg. The @entity5 group had a significantly heavier pituitary weight than @entity1373 and normal groups (p less than 0.01). In each group, there was no significant difference of pituitary weights between animals sacrificed at different intervals after E2 withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

[ @entity172 -induced XXXX --in relation to the changes in the pituitary gland after @entity172 withdrawal].

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen'] @entity2691 :: ('MESH:C015854', 'Chemical') :: ['estradiol valerate'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'tumors'] @entity1373 :: ('MESH:D006965', 'Disease') :: ['hyperplasias', 'hyperplasia'] @entity977 :: ('MESH:D010911', 'Disease') :: ['Pituitary tumors', 'pituitary tumor', 'pituitary tumors'] @entity35 :: ('10116', 'Species') :: ['Wistar', 'rats']
@entity977 :: (MESH:D010911,Disease) :: ['pituitary tumors']
