Ultrastructural Organization of the Corpus Luteum of the Indian Emballonurid Bat, Taphozous longimanus (Hardwicke)

The paper describes the ultrastructural organization of the corpus luteum of the emballonurid bat, Taphozous longimanus (Hardwicke). This bat is continuously asychronous breeder, exhibiting aseasonal polyoestry. During the early part of gestation, the luteal cells are compactly arranged with clearly demarcated boundaries, and show only moderate hypertrophy. Ultrastructural study of luteal cells during early pregnancy reveals the presence of irregularly shaped euchromatic nucleus, rod-shaped mitochondria with tubular or vesicular cristae, numerous lipid droplets and profiles of smooth/agranular endoplasmic reticulum in the form of short tubules or vesicles. The close association of mitochondria with lipid droplets and agranular endoplasmic reticulum in the luteal cells suggests that these cells are actively involved in steroidogenesis. During mid-pregnancy, the luteal cells are hypertrophied and are highly vacuolated. Large number of hypertrophied mitochondria, increased profiles of tubular cisternae of smooth endoplasmic reticulum and abundant lipid droplets in the cytoplasm of luteal cells during mid-pregnancy indicate an increase in the steroidogenic activity.