A variant source of arterial supply to the ascending, transverse and descending colon.

Anatomic variations involving arterial supply of the large intestines are of clinical significance. Variations range from the pattern of origin, branching and territorial supply. The colon, the part of the large intestine, usually receives its arterial blood supply from branches of the superior and inferior mesenteric arteries. However, anatomic variation in this vascular arrangement has been reported, with vascular anatomy of the right colon being described as complex and more variable compared with the left colon. During routine cadaveric dissection of the supracolic and infracolic viscera, we encountered an additional mesenteric artery originating directly from the anterior surface of the abdominal aorta between the origins of the superior and inferior mesenteric arteries. This additional "inferior mesenteric artery" ran obliquely superiorly toward the left colon giving rise to two branches supplying the distal part of the ascending colon, the transverse colon and the proximal part of the descending colon. Awareness and knowledge of this anatomic variation are important for radiologists and surgeons to improve the quality of surgery and avoid both intra- and postoperative complications during surgical procedures of the colon.

Survival of neural progenitor cells from the subventricular zone of the adult rat after transplantation into the host spinal cord of the same strain of adult rat.

The subventricular zone (SVZ) of the lateral ventricle of the mammalian forebrain is the major site in which neural progenitor cells (NPC) persist in the adult brain. The NPC are located beneath ventricular ependymal cells and have the capacity to self-renew and continuously produce neurons and glial cells. We have shown previously that neurospheres can be obtained from the brain of deceased adult rats and that neurosphere cells survive after transplantation into the spinal cord. In the present study, we investigated whether fresh NPC from living adult rats can survive and be integrated into host tissues after transplantation into the adult rat spinal cord of the same strain. We used rats expressing transgenic green fluorescent protein (GFP) as a donor to identify the transplanted NPCs. The SVZ tissues were obtained from the striatal wall of the lateral ventricle of adult GFP-rats and were grafted into lesions of the spinal cord at the cervical level. Two to 3 weeks after grafting, NPC migrated through the host tissue 0.5-1 mm away from the implantation site, and were integrated into the white matter of the host spinal cord. Surviving NPC exhibited immunohistochemical phenotypes of astrocytes (glial fibrillary acidic protein), but not for neurons (alpha-tubulin III) or oligodendrocytes (Rip; Hybridoma Bank, Iowa City, IA, USA). Thus, NPC from the SVZ of adult rats can survive and differentiate into at least astrocytes, which can then be integrated into host tissue after transplantation into spinal cord lesions in the adult rat.

Poly lactic acid--caprolactone copolymer tube with a denatured skeletal muscle segment inside as a guide for peripheral nerve regeneration: a morphological and electrophysiological evaluation of the regenerated nerves.

A biodegradable copolymer of poly L-lactic acid and epsilon-caprolactone (PLAC) was manufactured into a tube, in which a denatured skeletal muscle segment was placed longitudinally. This model tube was implanted as a guide to promote nerve regeneration across a 5 cm gap in the rabbit sciatic nerve. Five months after implantation, good nerve regeneration was found throughout the graft and in the distal host nerve. The population (29.6/16 x 10(2) microm(2)) of regenerated nerves in the graft was higher than that of the contralateral normal sciatic nerve (18.0/16 x 10(2) microm(2)). Regenerated nerve fibers extended to the distal host nerve. The number of myelinated fibers was 13.7/16 x 10(2) microm(2) at a level 1.5 cm from the distal suture. The diameters (below 2 microm) of most regenerated myelinated (nerves in the graft and in the distal host nerve were much smaller than those (6-8 microm) of normal nerves. Electrophysiological evaluation showed that the hindlimb muscle (gastrocnemius) was innervated by motor nerves in all animals 5 months after implantation. These results indicate that the PLAC tube with a denatured muscle segment inside provided good conditions for nerve fiber regrowth. The PLAC tube is thought to protect the denatured muscle segment from rapid dissociation in the host tissue.

Extracellular matrix of human amnion manufactured into tubes as conduits for peripheral nerve regeneration.

The human amnion consists of the epithelial cell layer and underlying connective tissue. After removing the epithelial cells, the resulting acellular connective tissue matrix was manufactured into thin dry sheets called amnion matrix sheets. The sheets were further processed into tubes, amnion matrix tubes (AMTs), of varying diameters, with the walls of varying numbers of amnion matrix sheets with or without a gelatin coating. The AMTs were implanted into rat sciatic nerves. Regenerating nerves extended in bundles through tubes of 1-2 mm in diameter and further elongated into host distal nerves 1-3 weeks after implantation. Morphometrical analysis of the regenerated nerve cable at the middle of each amnion matrix tube 3 weeks after implantation was performed. The average numbers of myelinated axons were almost the same (ca. 80-112/10(4) microm(2)) in AMTs of 1-2 mm in diameter, as in the normal sciatic nerve (ca. 95/10(4) microm(2)). No myelinated fibers were found in AMTs composed of multiple thin tubes of 0.2 mm in diameter. The myelinated axons were thinner in implanted tubes than those in the normal sciatic nerve. The rate of occurrences of myelinated axons less than 4 microm in diameter was significantly higher in the AMTs, whereas axons in the normal sciatic nerve were diverse in distribution, with the highest population at 8-12 microm in diameter. Reinnervation to the gastrocnemius muscle was demonstrated electrophysiologically 9 months after implantation. It was concluded that the extracellular matrix sheet from the human amnion is an effective conduit material for peripheral nerve regeneration.