Microvascular architecture in the central nervous system of Ambystoma mexicanum (Caudata, Ambystomatidae). A light, and transmission and scanning electron microscopy study

A combination of light, and scanning and transmission electron microscopy of vascular corrosion casts was utilized to study the structure and spatial organization of intraparenchymal microvessels in the central nervous system of the urodele Ambystoma mexicanum (Shaw, 1789). The angioarchitectural pattern consists of both single and paired vessels, but the single ones are prevalent. The meningeal vessels give origin to both single and paired elements. The paired vessels are bent and twisted and extend into the neural wall to various depths. Their two limbs are apposed throughout their length and are connected by a U-shaped terminal loop. The cross-sectioned single and paired vessels have variable diameters. The hairpin-shaped vascular pairs do not branch into secondary loops and no anastomotic intraparenchymal connections are observed with single or paired neighbouring structures. All intraparenchymal vessels are structurally interpreted as capillaries. The paired vessels of Ambystoma mexicanum resemble those found in a few vertebrates whose brain vascular pattern is represented only by paired structures.