Arteriolar Branching Patterns in the Brain of the Fruit Bats (Pteropus lylei)

Abstract

The traditional view that Old World fruit bats (Megachiroptera) and insect or echolocating bats (Microchiroptera) are closely related has been challenged by claims that megachiroptera are the sister group to flying lemurs (Dermoptera) or Primates. Thus, the vascular morphology was examined to ascertain whether the arteriolar branching patterns in the head region of the fruit bat might reveal the primate characteristics. The arteriolar branching patterns for four regions of the brain (cerebrum, cerebellum, pons and medulla) in the fruit bat (Pteropus lylei) have been studied in detail using the vascular corrosion cast / SEM technique. It is found that most of the penetrating arterioles in all four regions of the brain run perpendicularly to their superficial artery. The medullar penetrating arterioles are tortuous after branching. The right angle branching in the cerebrum and cerebellum are similar in the primate, thus, this anatomical feature may be indicates the relative evolution between the megachiroptera and primate. Furthermore, this evidence may cause the reduction of the risk factor for atherosclerosis in the brain while decreasing the arterial blood pressure. The tortuous penetrating arterioles in the medulla may be suitable for the movement of the upper cervical joint. However, evidence that concerning the arteriolar branching patterns of the microchiroptera is not observed. In addition, further study in the angioarchitecture of the microchiroptera’s brain in relation to megachiroptera and other primates is suggested.