title: Seasonal changes in the sensitivity of spayed ewes to progesterone and oestrogen.
mesh_terms: D000818:Animals; D002369:Castration; D004967:Estrogens / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D012621:Seasons; D012756:Sheep
chemical_list: D004967:Estrogens; D011374:Progesterone