div class=trans-pagebuttonPage 1button div class=trans-image amp-img class=trans-thumb alt=Page 1: Effect of Ethisterone β-Œstradiol and Progesterone on the Phagocytic Activity of the Reticulo-Endothelial System src=https:reader031fdocumentorgreader031viewer2022020312575068091a28ab0f07ae4e19html5thumbnails1jpg width=142 height=106 layout=responsive amp-img divp© 1957 Nature Publishing Grouppdiv