{'fraction_non_alphanumeric': 0.02512998266897747, 'fraction_numerical': 0.014731369150779897, 'mean_word_length': 5.078947368421052, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Progesterone in uterus and plasma. VI. Uterine progesterone receptors during the estrus cycle and implantation in the guinea pig.

The concentration of the progesterone cytosol receptor in the uterus shows marked variations during the estrus cycle. It is maximum in proestrus (about 40,000 binding sites per cell) and falls progressively during estrus and postestrus to attain a 16-fold lower value in diestrus. The receptor has a sedimentation coefficient (measured by sucrose gradient centrifugation) of 6.7 S during proestrus. In estrus, 6.7 S and 4.5 S binders are present, and the 4.5 S binder is predominant in postestrus and finally found exclusively in diestrus. One cannot differentiate 3 and 7 day pregnant animals by the concentration and the sedimentation coefficient of the progesterone receptors from the corresponding non-pregnant guinea pigs. Thus the implantation takes place at a moment when the concentration of receptor is very low, suggesting that implantation is controlled by progesterone secreted previously (perhaps in the pre-ovulatory period). The concentration of progesterone receptor in the uterus is positively controlle...