Kurl R N, Borthwick N M
J Endocrinol. 1979 Oct;83(1):41-51.
The concentrations of progesterone receptors in uterine cytoplasm and nuclei were measured during the oestrous cycle of the rat. The concentration of cytoplasmic progesterone receptors was highest at pro-oestrus and declined at oestrus to reach lowest levels at metoestrus before rising at dioestrus. Similar changes were observed in the concentration of nuclear progesterone receptors, the highest levels being present at pro-oestrus and dioestrus. In addition, both activities A and B of RNA polymerase mirrored these alterations in nuclear receptor levels.