Conversion of cholesterol to progesterone by turtle corpus luteum

Abstract

Homogenates of corpora lutea from the snapping turtle, Chelydra serpentina serpentina were capable of converting small (< 1%) amounts of cholesterol- 3H to progesterone- 3H. There was about twice as much steroidogenic activity in corpora lutea taken from animals still carrying oviducal eggs as in those from animals that had laid their eggs. However, the latter showed up to an 80% increase in conversion of cholesterol to progesterone when turtle pituitary homogenate was incubated along with the luteal homogenate. Approximately 4 and 9 mg/g of free and esterified sterol, respectively, were found in the turtle corpus luteum. These results suggest that the corpus luteum of the oviparous turtle functions as a steroidogenic organ.