Fine Structure of the Corpus Luteum of the Snapping Turtle, Chelydra serpentina

After ovulation the granulosa cells of the corpus luteum of the snapping turtle, Chelydra serpentina, undergo hypertrophy (luteinization) to become granulosa lutein cells, similar to those of other reptiles and mammals. The process of degeneration is characterized by massive fibrosis from the theca interna. The turtle corpus luteum shares certain ultrastructural characteristics with the mammalian corpus luteum which are suggestive of steroidogenesis. These features include the abundance of agranular endoplasmic reticulum, the presence of cisternal whorls, and close association of lipid droplets with mitochondria and agranular endoplasmic reticulum. The significance of this in regard to steroid synthesis is discussed.