Plasma Progesterone and Gonadotrophin Levels During the Estrous Cycle of the Guinea Pig

Abstract
Blood samples were collected once daily throughout the estrous cycle (and at more frequent intervals from the time of vaginal opening) from guinea pigs fitted with indwelling atrial catheters. Progesterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the plasma were measured by radioimmunoassay.