title: Ultrastructural changes in the guinea-pig placenta, with special reference to organelles associated with steroidogenesis.
mesh_terms: D000818:Animals; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005260:Female; D006168:Guinea Pigs / Q000033:anatomy & histology*; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D010920:Placenta / Q000378:metabolism / Q000648:ultrastructure*; D011247:Pregnancy; D011374:Progesterone / Q000096:biosynthesis*; D013997:Time Factors
chemical_list: D011374:Progesterone