Lumbosacral anterolateral spinal arteries and brief review of "accessory" longitudinal arteries of the spinal cord.

The lumbosacral anterolateral spinal arteries (LALSA) were studied in 14 injected lumbosacral spinal cords. Contrary to many previously published opinions, which claimed that virtually all of the formerly described "accessory" longitudinal arteries of the vasa corona, were too inconstant to be of significance, the LALSA in this series were reliably present bilaterally and averaged a length of 8.4 cm. They ran in the acute angles formed by the emergence of the fascicles of the lumbosacral anterior spinal nerve roots and in this position, served as the origin for most of the proximal radicular arteries that supply the cranial half of the motor roots of the cauda equina. A review of the literature and analysis of other accessory longitudinal spinal arteries revealed that two other pairs of accessory spinal vessels, the lateral cervical spinal arteries (LCSA) and the lateral spinal arterial axes (LSA), have a demonstrable functional role and were sufficiently constant, along with the LALSA, to warrant inclusion in detailed descriptions of human spinal cord vasculature.

Stabilizing role of the basement membrane and dermal fibers during newt limb regeneration.

BACKGROUND: Following amputation of a newt limb, tissues at the amputation site undergo histolysis to give rise to a growth bud, or blastema, but they also provide a base on which the regenerate is constructed. Studies suggest that dermal tissues may differentially resist histolysis. METHODS AND RESULTS: To examine stability of tissues at the amputation site, more than 80 preblastemal staged regenerating limbs were examined histologically. Initially, all soft tissues not attached to bone retracted and were covered by migrating epithelium. The dermis was seen to be stable during the first week postamputation. Muscle dedifferentiated and was heavily stained with anti-tenascin antibodies, but the intact overlying dermis was unstained. Fiber bundles, revealed by staining with phosphotungstic acid hematoxylin, isolated the dermis from dedifferentiating deeper tissues during the first week postamputation, but partially broke down during the second week. However, the basement membrane (BM) remained as the distalmost intact structure at the amputation site in all limbs examined. The BM was the foundation for new BM synthesis which preceded dermis synthesis in the base of the blastema during the second week, even while undifferentiated cells were accumulating centrally. CONCLUSIONS: We suggest that the dermis resists histolysis long enough for new BM to form in continuity with that of the stump. Dermis formation (dermogenesis) distal to the amputation plane begins early as in mammalian healing but is not completed until after blastema formation. Thus, factors that inhibit dermal closure appear to distinguish regenerating from non-regenerating appendages.

Malformations of the liver: some prenatal and postnatal developmental aspects.

The discovery of a large articulated lobe weighing 165.4 g dependent from the anterior margin of the left liver lobe in a 93-year-old female culminated two decades of observation of anomalous liver conditions in anatomic cadavers. When this data was compared with the information previously recorded from a series of 52 perinatal livers, remarkable discrepancies between the adult and perinatal incidences of various anomalous manifestations were noted. Ectopic accessory lobes were very rare in our adult series as well as in the groups reported in literature reviews. However, they were a relatively common occurrence in the perinatal cases, as were also gallbladder bridges of hepatic tissue, hypertrophic papillary lobes, and marked accessory fissures. In contradistinction, marginal accessory lobes were not noticed in any of the perinatal livers. Because the liver undergoes considerable postnatal reformation, it was concluded that most ectopic lobes, gallbladder bridges, hypertrophic caudate lobe extensions, and accessory fissures disappear during postnatal remodeling, whereas marginal accessory lobes may result from retention of the original perinatal boundaries of the anterior liver margins.

Intimal musculature of the lower anterior spinal artery.

STUDY DESIGN: This was a descriptive microscopic investigation of the smooth musculature in the human lower anterior spinal artery using anatomic cadaver tissues with supporting data derived from angiographic studies of neonatal cadavers. OBJECTIVE: To determine the extent and configuration of the intimal musculature in the lower anterior spinal artery and deduce the probable influence it has on the lower spinal cord blood flow, as well as its effects on the axial anastomotic potentials during aortic cross-clamping. SUMMARY OF BACKGROUND DATA: The high incidence of ischemic spinal cord injury after aortic cross-clamping has led to many studies of autoregulation of the spinal cord blood flow, but none have identified the probable vascular mechanisms. METHODS: Spinal tissue blocks that included the mid-thoracic and thoracolumbar anterior spinal artery, and sections of excised anterior spinal artery were dissected from spinal cords of 16 cadavers, refixed in Bouin's solution, paraffin embedded, and microscopically studied in sections processed in Masson's trichrome stain. A radioangiographic study of barium-perfused spines of neonatal cadavers was used to substantiate histologic observations. RESULTS: The smooth muscle of the tunica media of the lower anterior spinal artery is reinforced by a conspicuous longitudinally disposed layer of intimal muscle. At the junction of the arteria medullaris magna and the anterior spinal artery, this muscle forms intimal cushions that can dramatically alter the luminal diameters of the vessels involved. CONCLUSION: The described muscular characteristics of the lower anterior spinal artery indicate it has a previously unsuspected capacity to control extrinsic and intrinsic aspects of the lower spinal cord blood flow, a factor that should be considered in clinical and experimental procedures involving spinal cord collateral circulation.

Microsurgical anastomosis of the rabbit oviduct using 9-0 monofilament polyglycolic acid suture.

As part of a larger study to determine which factors are important in fallopian tube reconstruction, 9-0 monofilament polyglycolic acid suture on a 145 micron-needle was used for rabbit oviduct microsurgical anastomosis. A 100% pregnancy rate in five rabbits with no disruption of the endosalpingial or muscular layers was noted. Of special note, the suture was totally resorbed, and no suture residuum or surrounging reaction was noted. The suture material appears to fulfill the criteria for an ideal suture described at the beginning of the paper. This is the first report of the use of a 9-0 monofilament polyglycolic acid suture.