Examination of the hearts of Eptatretus burgeri using histological analysis

抄録

The heart creates positive and negative pressure in a regular rhythm to pump blood. The cardiac chambers seen in vertebrates are an advanced pump design. Many species, such as the hagfish, still have accessory pumps, but they are considered vestigial. Additionally, the processes by which the circulatory system develops in vertebrates, including heart development, are largely unknown. In this study, we examined the heart of hagfish (Eptatretus burgeri) using histological analysis. In E. burgeri, three types of hearts were observed: branchial, cardinal, and portal. Photomicrographs showed that there are many empty spaces in all three types. These hearts pump blood in and out of the sponge to absorb and discharge water. The cardinal heart near the brain in E. burgeri may be primitive because its cell structure is similar to that of skeletal muscle.