In the rat uterus, glycogen is located in the myometrium (Bo & Atkinson, 1952) and is highest at pro-oestrus and after oestrogen stimulation (Boettinger, 1946). After a single injection of 1 or 10 \g=m\goestrogen in ethanol, the glycogen concentration reached maximal levels at 14 h (Bitman, Cecil, Mench & Wrenn, 1965), while after injection of 10 \g=m\goestrogen in oil, the polysaccharide concentration reached the highest levels at 24 h (Bo, Maraspin & Smith, 1967). Unpublished histochemical studies in our laboratory and the biochemical observations of Bitman et al. (1965) indicate that glycogen of the uterus does not increase more after repeated treatment with oestrogen than it does after a single injection. The results, therefore, indicate that with regard to glycogen, the uterus may become refractory to repeated treatment with oestrogen. In order to confirm the above findings and to form the basis for future work on glycogen synthetase: glycogen phosphorylase activity ratios, studies were undertaken to determine whether the uterus was capable of responding to a second or a third injection of oestradiol-17/? dipropionate to a similar extent as it does to the first injection of the hormone.Holtzman rats, 65-71 days old and weighing 200+10 g, were housed three to a cage in an air-conditioned room (24°C). They were maintained on rat chow and tap water and were exposed to 14 h light per day. All rats were bilaterally ovariectomized and 10 days later were divided into groups according to treatment. The experimental rats received either one, two or three injections of oestrogen at 24-h intervals and were killed 24 h after the last treatment. All hormone injections were given subcutaneously in 0-1 ml oil; control rats received 0-1 ml vehicle. The rats were killed with sodium pentobarbitone and both uterine horns were removed, trimmed and blotted. The total uterine wet weight was determined to the nearest 0-2 mg on a torsion balance. A portion of uterine horn was placed in boiling 30 % KOH and analysed for glycogen by the indirect anthrone procedure (Seifter, Dayton, Novic & Muntwyler, 1950). The statistical analysis was performed at the Bowman Gray Computer Centre. The analysis of variance was determined and Duncan's multiple range test was used to locate significant differences.The results are presented in Table 1. Uterine wet weight increased significantly after each oestrogen treatment. Total glycogen increased significantly after the first and second injections, while the third injection maintained total glycogen at the level seen after the second. On the other hand, the concentration of uterine glycogen, which was based on wet weight, was significantly increased only after the first injection ; 25 END 59

No abstract

The purpose o f t h i s study was t o a s c e r t a i n t h e e f f e c t s o f d i f f e r e n t amounts of progesterone on estrogen-induced DNA synthesis i n the vaginal and lower c e r v i c a l e p i t h e l i a o f t h e r a t . Ovariectomized r a t s were i n j e c t e d subcutaneously w i t h 1 pg o f e s t r a d i o l -1 7~ d i p r opionate o r w i t h e s t r a d i o l and 1, 5, I0 o r 15 mg o f progesterone f o r three days; c o n t r o l r a t s received o i l . T r i t i a t e d thymidine was i nj e c t e d one hour p r i o r t o necropsy; the t i s s u e s were processed f o r autoradiographic study and t h e percentages o f labeled n u c l e i i n the basal l a y e r from the lower h a l f o f both the vagina and c e r v i x were determined. I n the group o f r a t s given e s t r a d i o l and 1 mg o f progesterone the thymidine uptake i n t h e vagina was s i g n i f i c a n t l y i ncreased over t h a t o f r a t s given o n l y estrogen. However, i n t h e r a t s t r e a t e d w i t h e s t r a d i o l and 5, 10 o r 15 mg o f progesterone, t h e extent o f DNA r e p l i c a t i o n i n the basal e p i t h e l i a l n u c l e i was s i m i l a r t o the estrogen group. basal e p i t h e l i u m from t h e lower h a l f o f the c e r v i x . estrogen-progesterone treatments increased the thymidine index i n the c e r v i c a l e p i t h e l i u m above t h a t o f estrogen alone; a d d i t i o n a l l y , 5, 10 o r 15 mg o f progesterone given w i t h estrogen suppressed DNA r e p l i c at i o n . p o r t i o n s o f t h e reproductive t r a c t respond d i f f e r e n t l y t o exogenous ovarian hormones. These responses were compared w i t h those o f the None o f t h e These data i n d i c a t e t h a t s t r a t i f i e d e p i t h e l i a o f these twoThe luminal e p i t h e l i a l c e l l s o f t h e female reproductive t r a c t undergo continuous renewal throughout l i f e ( B e r t a l a n f f y and Lau, '63). The r a t e s o f c e l l turnover f l u c t u a t e w i t h t h e d i f f e r e n t stages o f the estrous c y c l e and these v a r ia t i o n s a r e r e f l e c t i o n s o f t h e changes i n t h e l e v e l s o f c i r c u l a t i n g ovarian hormones (Lobe1 e t al., '67; Leroy e t al., '69; Krueger and Maibenco, ' 7 2 ) . I n t h e i n t a c t c y c l i n g r a t , maximal m i t o t i c a c t i v i t y i n the vaginal e p i t h e l i u m occurs l a t e r during the c y c l e (second day o f d i e s t r u s ) than t h a t i n the u t e r i n e 123

This study was undertaken t o determine whether sonication of the ovaries on day 8 of pregnancy would alter fetal development in the rat. Mating was confirmed by the presence of sperm (day 1 of gestation) in the vaginal smear, and the rats were grouped and treated on day 8 as follows: Group I (controls) had both ovaries surgically exposed to sonic gel for 10 min/ovary; group I1 received 10 watts/cmz temporal peak intensity of pulsed ultrasound through the body wall for 10 min/ovary; group I11 received 100 watts/cmz in a similar manner as group 11; group IV was treated the same as group I11 except the ultrasound was applied directly to the surgically exposed ovaries. The frequency employed was 1.9 mHz. The animals were sacrificed on days 15-17, implantation sites and resorptions were counted, and fetal viability was determined. There were no statistically significant differences in the percentage of resorptions among any of the groups. The data indicated that the ovaries were functional with regard t o fetal development .