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.

Formation of binucleated cardiac myocytes in rat heart: I. Role of actin-myosin contractile ring.

Cardiac myocytes in rat hearts lose their ability to undergo cytokinesis between day 3 and day 4, resulting in the formation of binucleated myocytes. Failure in the formation of the actin-myosin contractile ring could cause cardiac myocytes to be defective in cytokinesis. Enzymatically isolated cardiac myocytes from 2- and 4-day-old rats were employed to investigate the organisation and distribution of actin, myomesin, and myosin by rhodamine phalloidin, anti-myomesin, and isoform-specific anti-myosin antibodies, respectively. Interestingly, the actin-myosin contractile ring was formed in mitotic myocytes from both 2- and 4-day-old animals. The changes in organisation and distribution of actin, myosin and myomesin in mitotic myocytes from 4-day-old rats were similar to those from 2-day-old rats, except that there were longitudinal actin filaments in the cytoplasm of mitotic myocytes from 4-day-old rats. In mitotic myocytes from both 2- and 4-day-old rats, actin disassembled in prometaphase, concentrated in the equator of the mitotic spindle in late anaphase, and formed a circumferential intensely staining band in early telophase. Cytoplasmic myosin was evenly distributed in the cytoplasm as small spots, and appeared to associate with the cell membrane from interphase to early anaphase. It became progressively more concentrated in association with the cortical membrane in the equator region in late anaphase, formed a ring-like structure in early telophase, and remained associated with adjacent membrane at the cleavage furrow until late telophase. Sarcomeric myosin and myomesin were only partially disassembled in mitotic myocytes from both 2- and 4-day-old animals. The present study showed that the actin-myosin contractile ring was actually formed during the binucleation process of cardiac myocytes. Molecules involved in the latter stages of cytokinesis may be responsible for incomplete cytokinesis during the binucleation process.

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.

Traumatic abducens nerve paresis in a child.

Trauma is a frequent cause for abducens (sixth) nerve paresis in a child, usually attributed to injury along the nerve's course. An unusual focal lesion of the sixth nerve nucleus is described.

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.

Changes in red nucleus neuronal development following maternal alcohol exposure.

The red nucleus of Swiss Webster mouse fetuses was examined for morphological changes following maternal ethanol exposure. Pregnant females were given a liquid diet containing 30% or 0% ethanol-derived calories. Changes in numerical density of neurons and in neuronal nuclear volume were found in the rostral red (RR) nucleus of ethanol-exposed pups but not in the caudal red (CR) nucleus. Because of the integrative nature of the RR, changes in neuronal morphology that might relate to synaptic connections could affect the behavioral response mechanisms of these offspring.

Neuron development in the superior colliculus of the fetal mouse following maternal alcohol exposure.

Pregnant Swiss Webster mice were given a liquid diet with ethanol (EtOH) or isocaloric amounts of maltose dextrin on gestation day (GD) 0 through 18. On GD 18, maternal blood samples were obtained. Fetuses were then removed and fetal brains were prepared for light microscopy. Fetal weight was reduced in the EtOH-exposed group. The ratio of midbrain cross sectional area to cerebral aqueduct was reduced in the ethanol group, while the density of neuronal nuclear population in both the dense outer layer (DS) and sparse inner layer (SS) of the developing superior colliculus was increased. Mean nuclear volume was decreased in the SS.

Persistent left hepatic venous connection with the coronary sinus.

An anomalous direct connection between the left hepatic vein and the coronary sinus in two cadavers is described. The normal development of the central systemic venous system with particular reference to the hepatic region is reviewed and a possible explanation for the present configuration is put forth. Although this configuration of venous anomaly without abnormal shunting of blood is considered clinically insignificant, the association of cardiac arrhythmias with these variations heightens the importance of their identification.

Persistent left superior vena cava and associated structural and functional considerations.

Potentially significant associations are presented between anomalous systemic venous return (including both left superior vena cava and left hepatic venous drainage to the coronary sinus), a history of atrial fibrillation and a forme fruste of cor triatriatum in an elderly woman. Lack of associated structural defects or functional deficits makes it difficult to assess the frequency of occurrence in the general population of bilateral superior venae cavae in association with a persistent left hepatic vein draining into the coronary sinus. However, the potential for these systemic venous anomalies needs to be considered when unexplained arrhythmias are encountered. More specifically, the size of the coronary sinus needs to be assessed in patients with arrhythmia.