Dorsal Sac Research Articles

Volatile fatty acid metabolism by epithelial cells isolated from different areas of the ewe rumen.

Cells were harvested from four rumen locations in four 2- to 3-yr-old ewes fed fescue hay to determine whether cell origin has an effect on cellular VFA metabolism. Tissue (approximately 150 cm2) was excised from the anterior cranial pillar, ventral sac floor, caudal pillar surface, and dorsal sac ceiling. Cells were isolated using serial tryptic digestion. One milliliter of isolate was incubated for 2 h in 6 mL of medium containing 25 mM propionate and 10 mM butyrate. Incubations were terminated at 0, 30, 60, 90, and 120 min and analyzed for beta-hydroxybutyrate, acetoacetate, lactate, and pyruvate. Cell yield was 22, 22, 24, and 14 (+/- 6) x 106 cells/mL, and viability was 92, 92, 94, and 87% for anterior cranial pillar, ventral sac floor, caudal pillar surface, and dorsal sac ceiling, respectively. All metabolite concentrations and ratios of redox pairs increased throughout the incubations, indicating continuous cellular activity. Final 2-h concentrations (nmol/10(6) cells) were 123, 113, 163, and 158 (+/- 35) for beta-hydroxybutyrate; 38, 42, 24, and 45 (+/- 10) for acetoacetate; 25.3, 20.6, 10.1, and 20.4 (+/- 5.6) for lactate; and 2.54, 0.98, 1.06, and 1.31 (+/- 0.61) for pyruvate in the anterior cranial pillar, ventral sac floor, caudal pillar surface and dorsal sac ceiling incubations, respectively. Origin of rumen tissue had no significant effect on metabolite production, indicating that cellular location is not a critical factor that affects rate of rumen epithelial cell VFA metabolism under these specific in vitro conditions.

Effect of short‐term underfeeding on weight of splanchnic organs in ewes

We assessed the effect of short‐term underfeeding on weight and protein mass of splanchnic tissues in adult ewes submitted to a factorial experimental design. In a pre‐experimental period, 18 ewes divided into 2 groups of 9 were fed a second cut of natural grassland hay during 4 weeks at 112 or 38% of their energy maintenance requirements. Three ewes of each group were then fed the same hay during 4 weeks at either low (group L), moderate (group M) or high intake (group H), corresponding to 38, 75 or 112% of their energy maintenance requirements, respectively, then slaughtered. Fresh weight and protein mass of splanchnic organs were measured. No carry‐over effect of the pre‐experimental level of intake on weight and protein mass was observed for any splanchnic organs. Splanchnic tissues contributed at 10.7 and 8.6% to the decrease in live weight for groups M and L, respectively. The decrease in weight of splanchnic tissues (‐15%) was mainly attributed to reticulorumen (‐23%), liver (‐21%), and at a lesser extent small intestine (‐11%). No large change in the mass ratio between mucosa and muscular‐sercsa in both dorsal and ventral sacs occurred in the rumen wall. These results are discussed together with previous published results on long‐term underfed ewes, and suggest that the decrease in energy expenditure in whole animal induced by underfeeding is mainly related to the decrease in splanchnic weight at short‐term, and to the decrease in other tissues at long‐term, splanchnic weight being stabilized.

A potential use of a synthetic retinoid TAC-101 as an orally active agent that blocks angiogenesis in liver metastases of human stomach cancer cells.

TAC‐101 (4‐[3,5‐bis(trimethylsilyl)benzamido]benzoic acid) is a novel, synthetic retinoid that is effective against liver metastases of human gastrointestinal cancer cells such as the human stomach carcinoma line AZ‐521 in animal models, and is currently in use in phase I cancer trials. However, the mechanism of its antimetastatic action is still poorly understood. Tumor metastasis depends on angiogenesis, and various retinoids have been found to exhibit antiangiogenic activity. Based on these findings we here examined the antiangiogenic effects of TAC‐101. Oral administration of TAC‐101 (2‐8 mg/kg/day) resulted in a drastic suppression of the AZ‐521 cell‐induced angiogenesis in a mouse dorsal air sac assay system, compared to the vehicle alone. Immunohistochemical analysis with antibody against the endothelial marker CD31 revealed a significant reduction in microvessel density in liver metastases from animals treated with TAC‐101 (8 mg/kg p.o.), compared to liver metastases from the untreated control animals. The ability of TAC‐101 (8 mg/kg p.o.) to prevent experimental liver metastasis of AZ‐521 cells in athymic nude mice was comparable with that of the known angiogenesis inhibitor TNP‐470 (30 mg/kg s.c.). TAC‐101 also affected angiogenesis in chorioallantoic membranes and some functions of endothelial cells associated with angiogenesis, whereas the retinoid failed to suppress AZ‐521 cell proliferation directly. These data suggest that the TAC‐101 is an orally active antiangiogenic agent and that this antiangiogenic property may contribute to its efficacy against liver metastasis of human stomach cancer cells.

Ergot alkaloid transport across ruminant gastric tissues.

Ergot alkaloids cause fescue toxicosis when livestock graze endophyte-infected tall fescue. It is generally accepted that ergovaline is the toxic component of endophyte-infected tall fescue, but there is no direct evidence to support this hypothesis. The objective of this study was to examine relative and potential transport of ergoline and ergopeptine alkaloids across isolated gastric tissues in vitro. Sheep ruminal and omasal tissues were surgically removed and placed in parabiotic chambers. Equimolar concentrations of lysergic acid, lysergol, ergonovine, ergotamine, and ergocryptine were added to a Kreb's Ringer phosphate (KRP) solution on the mucosal side of the tissue. Tissue was incubated in near-physiological conditions for 240 min. Samples were taken from KRP on the serosal side of the chambers at times 0, 30, 60, 120, 180, and 240 min and analyzed for ergot alkaloids by competitive ELISA. The serosal KRP remaining after incubation was freeze-dried and the alkaloid species quantified by HPLC. The area of ruminal and omasal tissues was measured and the potential transportable alkaloids calculated by multiplying the moles of transported alkaloids per square centimeter of each tissue type by the surface area of the tissue. Studies were conducted to compare alkaloid transport in reticular, ruminal, and omasal tissues and to determine whether transport was active or passive. Ruminal tissue had greater ergot alkaloid transport potential than omasal tissue (85 vs 60 mmol) because of a larger surface area. The ruminal posterior dorsal sac had the greatest potential for alkaloid transport, but the other ruminal tissues were not different from one another. Alkaloid transport was less among reticular tissues than among ruminal tissues. Transport of alkaloids seemed to be an active process. The alkaloids with greatest transport potential were lysergic acid and lysergol. Ergopeptine alkaloids tended to pass across omasal tissues in greater quantities than across ruminal tissues, but their transport was minimal compared to lysergic acid and lysergol.

Combined treatment with TNP-470 and 5-fluorouracil effectively inhibits growth of murine colon cancer cells in vitro and liver metastasis in vivo.

The combined effects of TNP-470 (TNP), a semisynthetic analogue of fumagillin, and 5-fluorouracil (5FU), a representative chemotherapeutic agent for colorectal cancer, were investigated using murine colon 26 adenocarcinoma (CT 26) cells. In a cell-proliferation study in vitro, 50% inhibitory concentrations (IC50) were determined to be 5.2 microg/ml and 240 ng/ml for TNP and 5FU, respectively. When CT 26 cells were treated with TNP and 5FU in combination, a remarkable cytotoxic effect was obtained. Isobologram analysis revealed synergism of these two agents in inhibition of the cell growth. In vivo, using a dorsal air sac assay, we found that TNP significantly inhibited the CT 26-induced angiogenesis. In addition, the combination of TNP and 5FU exerted a synergistic anti-tumor effect in a model of hepatic metastasis by portal injection of CT 26 cells. Since TNP is known to exert inhibitory effects on tumor cell growth through suppression of cell cycle progress from the G1 to S phases as well as neovascularization, it is speculated that the treatment with TNP enhanced the anti-tumor effect of 5FU through suppression of the cell cycle and tumor-derived angiogenesis. Taken together, these results suggest that combined treatment with TNP and 5FU is potentially useful for inhibition of tumor cell growth and liver metastasis of colorectal cancer.

The vesicular forebrain (pseudo-aprosencephaly): a missing link in the teratogenetic spectrum of the defective brain anlage and its discrimination from aprosencephaly.

Two cases out of a sample of 41 fetuses and infants with prosencephalic malformation, observed at the Institute of Pathology and Department of Neuropathology of the University of Heidelberg, are described here in detail. These cases presented grossly with microcephaly and missing forebrain, appearing to be cases of aprosencephaly. However, in one of these cases glio-mesenchymal membranes with an ependymal outline, consistent with the microscopic appearance of the dorsal sac membrane in holoprosencephaly and obviously representing remnants of a collapsed primitive prosencephalic vesicle, could be demonstrated. In the other case only hindbrain structures, with the exception of the cerebellum, were present without any demonstrable remnants of a prosencephalon. We propose that the microscopic specification of a primitive prosencephalic vesicle in the first case and similar cases does not justify the diagnosis of atelencephaly/aprosencephaly because the prosencephalon was not really missing (pseudo-aprosencephaly). The prosencephalic anlage had been formed but remained vesicular without further differentiation of a holospheric brain mantle as in common holoprosencephaly ('vesicular forebrain'). We believe that pseudo-aprosencephaly represents the most primitive form of holoprosencephaly, in which the forebrain remains as a complete sac, linking classical holoprosencephaly with 'true' aprosencephaly, i.e., defective prosencephalic anlage due to developmental arrest. The 'vesicular forebrain' allows one to extend the classification of Probst by an additional category which might be termed complete sac category, intercalated between the dorsal sac category and 'true' atelencephaly/aprosencephaly.

Neuroendoscopic surgery for specific forms of hydrocephalus.

Neuroendoscopic surgery was used to treat patients with various forms of hydrocephalus with specific pathophysiology, including long-standing overt ventriculomegaly in adulthood (LOVA), isolated unilateral hydrocephalus (IUH), isolated IV ventricle (IFV), disproportionately large IV ventricle (DLFV), isolated rhombencephalic ventricle (IRV), isolated quarto-ventriculomegaly (IQV), dorsal sac in holoprosencephaly (DS), and loculated ventricle (LV). A total of 26 operative procedures were performed, with neuroendoscopic surgery in 22 patients, 12 with unique forms of noncommunicating hydrocephalus and 10 with various types of postshunt isolated compartment. These procedures included III ventriculostomy, aqueductal plasty by both rostral and caudal approaches, foraminal plasty in the foramen of Monro/foramen of Magendie, septostomy, IV ventriculostomy, fenestration of septation in the loculated ventricle, fenestration of arachnoid cyst or cystic tumor obstructing a ventricle with or without tumor removal, and dorsal sac ventriculostomy. The characteristics of the cerebrospinal fluid (CSF) dynamics in the individual specific pathophysiologies were delineated by cardiac-gated cine-mode magnetic resonance imaging (MRI) before and after the endoscopic procedure. The consequent success rate (success = restoration of communication of the CSF pathway in the individual patients) was 19/22 (86.4%). The progression of ventricular dilatation was stopped in 17 of 19 patients (89.5%) in whom the endoscopic procedure was successful (radiologically arrested hydrocephalus). Improvement in the clinical symptoms and signs (clinically arrested hydrocephalus) was obtained in 15 of the patients (68.2% of all patients: 5 with LOVA, 3 with IQV, 5 with IUH and 2 with LV). Seven patients (2 LOVA, 2 IFV, 1 DS, 1 DFLV and 1 IRV) underwent a shunt procedure after the neuroendoscopic procedure(s). The postoperative changes of ventriculomegaly were complicated, reflecting the differences in the brain parenchymal compliance and postoperatively corrected CSF flow dynamics in the major CSF pathway.

Antiangiogenic and antitumor effects of 14-membered ring macrolides on mouse B16 melanoma cells.

We examined the effects of macrolide antibiotics on tumor angiogenesis, tumor growth and metastasis in the B 16BL6 mouse melanoma and C57BL mouse system. Two 14-membered ring macrolide antibiotics, roxithromycin and clarithromycin, significantly reduced the dense capillary network area in a mouse dorsal air sac angiogenesis model, whereas a 15-membered ring macrolide, azithromycin, and a 16-membered ring macrolide, josamycin, did not show any inhibitory effect on angiogenesis at the same dose. Intraperitoneal administration of roxithromycin and clarithromycin at 50 mg/kg/day reduced the tumor size of B 16BL6 melanoma to about 41% and 56%, respectively, of that of the control, and significantly suppressed pulmonary metastasis of B16BL6 cells in a spontaneous system. Azithromycin and josamycin, on the other hand, did not inhibit tumor growth or pulmonary metastasis of B16BL6 cells. Immunohistochemistry revealed that roxithromycin and clarithromycin reduced the tumor vascularity and increased apoptosis of the tumor cells in vivo. These results suggest that 14-membered ring macrolides have antiangiogenic and antitumor effects and might have possible therapeutic applications.

Morphological features of holoprosencephaly

The gross and microscopic features of holoprosencephaly are described on the basis of five representative cases of the alobar and semilobar types, which were investigated by autopsy and/or magnetic resonance imaging. Alobar holoprosencephaly was distinguished from the semilobar type by its gross morphology: the brain neither separated horizontally into the hemispheres nor differentiated axially into the telencephalon and diencephalon. Dorsal cyst, which communicated with the prosencephalic common ventricle through a horseshoe‐shaped cerebral mantle defect, was present in all cases. The wall of the cyst, called the ‘dorsal sac’, consisted of ependymal remnants and leptomeninges, in which a layer of dysplastic cerebral tissue or heterotopic glioneural tissue was included in some cases. The dorsal sac extended from the hippocampal ridge and attached posteriorly to the epithalamic structure. The cerebral cortex showed abnormally formed convolutions with agyria, pachygyria or polymicrogyria in all the cases examined, without distinction between the alobar and semilobar types. The microscopic features of these cortices were poorly formed lamination, marginal glioneural heterotopia and periventricular aggregates of neuroblasts. Glomerular structures, which Mere devoid of neurons and consisted of fine dendrites and axons, were found in three cases of this series. These abnormal cortical structures, resulting from disordered neuronal migration, were considered characteristic microscopic findings of the holoprosencephalic brain. The current classification system advocated by DeMyer and Zeman, which depends on surface morphology, does not reflect the maturity of the brain as investigated histopathologically in this series.

Morphological study of the forestomach of the Japanese serow (Capricornis crispus).

Details of the morphology of the forestomach of the Japanese serow (Capricornis crispus) were examined macroscopically, and by light and scanning electron microscopy. The rumen was sac-like in shape, and the right accessory longitudinal groove was not visible externally. The reticulum was relatively small, while the omasum was oval and large. Inside the rumen, even in the dorsal sac, the ruminal papillae were densely distributed, although absent on the pillars. The caudodorsal coronary pillar was indistinct. In the ruminoreticular fold, ruminal papillae were observed even on the reticulum side. In the reticulum, the primary reticular fold was apparent and the ill-defined secondary folds were also detected in some reticular cells. In the omasum, the omasal laminae of four sizes were recognized. The fourth order of laminae was occasionally absent. Histological sections of ruminal papillae revealed that softly keratinized epithelium covered the entire ruminal mucosa. In the reticulum, soft keratinized epithelium was observed throughout, with the exception of the tips of reticular papillae on which the epithelium showed evidence of hard keratinization. The epithelium of the omasal laminae was moderately keratinized. On the floor of the reticular groove, interlaminar area and in the omasal groove, the accumulations of numerous eosinophilic cells were observed in the superficial region. Under the scanning electron microscope, shallow transverse grooves were seen on the surface of the ruminal papillae. In general, the surface structure seemed to be similar to that of sheep rather than cattle. Cellular formations of the collagen fibrils were observed at the subepithelial region. In conclusion, examination of the forestomach allows classification of the Japanese serows as requiring an intermediate type of feeding habit and being between concentrate selectors and grass-roughage eaters from a morphological view.

Fusobacterium necrophorum in ruminal contents and on the ruminal wall of cattle (1998)

Fusobacterium necrophorum was quantified from ruminal contents and ruminal wall tissue collected at slaughter. Livers were examined and scored for abscesses. The mean concentration of F. necrophorum on the ruminal wall ranged from 2.9 x 103 to 6.1x 105 per cm2 . The dorsal sac had the lowest counts, and dorsal blind and ventral sacs had the highest counts of F. necrophorum adherent to the ruminal wall. The concentrations of F. necrophorum in ruminal contents and on the ruminal wall did not appear to be related to presence or absence of abscessed livers or to severity of abscesses.

The use of toads (Bufo regularis) in a new biological assay for screening chemicals or drugs which induce leukaemia in man

Injection of Egyptian toads Bufo regularis, with adriamycin subcutaneously in the dorsal lymph sac at a dose level of 0.1 mg/toad, once every 3 weeks for 3 months induced pronounced alterations in the blood cells. These alterations were more or less similar to the criteria reported in human leukaemia. These changes were all comparable to those observed after the treatment of the experimental animals with the chemical carcinogen 7,12-dimethylbenz(a)anthracene. It is speculated that toads (Bufo regularis) can be used as biological test animals for screening chemicals or drugs which induce leukaemia in man.

Effects of 5-hydroxytryptamine agonists on myoelectric activity of the forestomach and antroduodenal area in sheep.

To increase knowledge of the role of 5-hydroxytryptamine (5-HT) receptors in the regulation of reticuloruminal, omasal and antroduodenal myoelectric activity in sheep, the effects of 5-HT agonists on forestomach and antroduodenal myoelectric activity have been investigated in conscious sheep. 5-Carboxamidotryptamine, methysergide, alpha-methyl-5-HT, 2-methyl-5-HT, cisapride, zacopride or metoclopramide were infused intravenously for 5 min and myoelectric recordings were obtained from electrodes chronically implanted in the reticulum, rumen (dorsal sac), omasal body, abomasal antrum and duodenal bulb. The integrated activity of the reticular and ruminal spike bursts was modified only by the highest doses of alpha-methyl-5-HT, 2-methyl-5-HT, metoclopramide and cisapride. A phase III-like activity pattern was recorded in the antroduodenal area with all 5-HT-ergic agents and a dose-dependent inhibition of myoelectric activity was recorded in both reticulorumen and omasum at the same time as the antroduodenal effects. In the forestomach, methysergide alone induced inhibition of ruminal secondary contractions; 5-HT, alpha-methyl-5-HT, cisapride and metoclopramide, moreover, evoked an initial dose-dependent increase in antral activity. These results suggest that 5-HT1, 5-HT2, 5-HT3 and 5-HT4 receptors are involved in the regulation of the migrating myoelectric complex in sheep and in the genesis of forestomach hypomotility that is occasionally recorded concomitantly with the spontaneous duodenal phase III in sheep. 5-HT4 receptors also have a prokinetic action in the antral area.

5‐Hydroxytryptamine induces forestomach hypomotility in sheep through 5‐HT4 receptors

The effects evoked by 5-hydroxytryptamine (5-HT; serotonin) on forestomach myoelectric activity were investigated in conscious sheep. Myoelectric signals were recorded with electrodes chronically implanted in the reticulum, rumen (dorsal sac) and omasal body, and were analysed by a computer-based method. The 5-HT receptors and the neuronal pathways involved in these actions were studied. The intravenous (i.v.) infusion of 5-HT (8 micrograms kg-1 min-1 for 5 min) evoked an inhibition of activity of the whole forestomach. Methiothepin, injected i.v. at 0.1 mg kg-1, inhibited rumen secondary contractions and omasum activity. However, forestomach activity remained unchanged after the administration of 0.2 mg kg-1 of ketanserin, ondansetron, tropisetron, GR-113808, phentolamine, propranolol, domperidone and naloxone. Atropine (0.2 mg kg-1), hexamethonium (2 mg kg-1) or haloperidol (0.1 mg kg-1) abolished rumen secondary cycles and inhibited omasum activity. In addition, atropine also suppressed primary cycles. GR-113808 blocked all 5-HT-induced effects. Furthermore, atropine or hexamethonium prevented the 5-HT-evoked inhibition of reticulorumen primary cycles. In contrast, the remaining antagonists did not alter the 5-HT-evoked forestomach hypomotility. In conclusion, 5-HT induces inhibition of forestomach myoelectric activity through 5-HT4 receptors, these actions being mediated by cholinergic neural pathways involving muscarinic and nicotinic receptors. However, adrenergic, dopaminergic or opiate pathways are not implicated.

Microvascularization of the pineal gland in the freshwater turtle, Pseudemys scripta elegans (Reptilia): A scanning electron microscopic study of vascular corrosion casts

Gross supply, microvascular patterns, and drainage routes of the pineal gland and its vascular relations with associated structures (dorsal sac, paraphysis, choroid plexus of the third ventricle) were studied by scanning electron microscopy of microvascular corrosion casts in 10 specimens of the freshwater turtle, Pseudemys scripta elegans. Light microscopy of tissue sections (one transverse and one longitudinal series) served to attribute cast vascular territories to anatomical structures. The tubular pineal gland body is supplied bilaterally by small branches of the saccular artery, a branch of the lateral choroidal artery. Branches of the diencephalic artery supply the pineal stalk. The pineal gland microvascular bed is a two-dimensional network that embraces the tubular gland. The network is made up mainly of venules with few true capillaries. Venules draining the ventral surface of the pineal gland body join those coming from the choroid plexus of the third ventricle and drain into the sagittal sinus. The less dense vascular network embracing the dorsal surface of the pineal body drains directly into the sagittal sinus. The pineal stalk drains into the diencephalic vein or directly into the sagittal sinus. No efferent (venous) vascular connections capable as transport route for pineal secretions toward surrounding telencephalic, diencephalic, or mesencephalic areas were found.

Intake and digestion in swamp buffaloes and cattle. 4. Particle size and buoyancy in relation to voluntary intake

SUMMARYThe buoyancy and distribution within the rumen of feed particles were measured to assess the extent to which particle buoyancy modulated the movement of particles within and from the reticulorumen. Two experiments conducted in north Queensland in 1988 involved swamp buffaloes (Bubalus bubalis)and crossbred cattle (Bos indicus × B. taurus) fed rice straw with various supplements of energy and protein, lablab (Lablab purpureus), verano (Stylosanthes hamata cv. verano) and two grasses, sorghum (Sorghum bicolor × S. sudanense) and pangola (Digitaria eriantha). Apparent passage rate of particles from the reticulorumen bore an inverse curvilinear relationship to particle size. Passage rate of the smallest particles, retained by a cloth of aperture 50 μm, was faster in buffaloes. Mean particle size of total rumen digesta was smaller in buffaloes than in cattle in Expt 1 with rice straw, but there was no difference between the forage diets offered in Expt 2. The large particle content in digesta (dry matter per kg) in the dorsal rumen was greater than that in the ventral rumen, which in turn was greater than that in the reticulum. The sedimentation rate of particles was measured by a procedure designed to interfere as little as possible with microbial fermentation. A curvilinear relationship was evident between sedimentation rate and particle size; the medium particles sedimented faster than the fine and large particles. Sedimentation rates of some particle fractions were greater in buffaloes than in cattle. Between diets there were marked differences in sedimentation rates of large particles, but these differences decreased with smaller particle size. Large particles from the dorsal sac sedimented faster than those from the ventral sac, and there was no obvious dorsal raft. There was no apparent relationship between particle buoyancy and ease of particle escape from the reticulorumen. The results are discussed in terms of current theories of the physical factors involved in the control of voluntary feed consumption by ruminants.

An octopus,Ocythoe, with a swimbladder and triple jets

A young female of the rarely seen pelagic octopodOcythoe tuberculata(Rafinesque, 1814) (Argonautoidea) survived for two days in captivity. It possessed a swimbladder and controlled its buoyancy. When swimming, the dorso-lateral corners of the mantle aperture were converted into dirigible structures (‘accessory funnels’), which jetted water from the upper chamber of the mantle cavity forwards, upwards, sideways or backwards. The dorsal sac or swimbladder lies on top of the visceral mass, has a duct into the mantle cavity, is supplied with a nerve and blood vessels and in immature specimens has thick gelatinous walls which contract peristaltically and contain spherical ‘amoeboid’ cells. The lumen is lined by a cuboidal epithelium 7 µm thick. In a ripe (2.2 kg) specimen the walls are less gelatinous and the lumen is large and permanently expanded (volume 110 ml). The living ocythoe was negatively buoyant when delivered to the laboratory and regained and lost buoyancy twice during captivity. On one occasion it was observed to release gas as it plunged to the bottom. The origin and nature of the gas is not known. Cephalopods have a variety of mechanisms for buoyancy control butOcythoeappears to be the only species with a swimbladder. The structure is absent in the dwarf male. Probably it is derived embryologically from the shell Anlagen.

Cerebral retroflexion in holoprosencephaly developed following ventriculo-peritoneal shunting: A case report

Retroflexion of the hypoplastic fused cerebrum is a rare condition in holoprosencephaly. We describe a new case of this entity in a 7-year-old boy with alobar holoprosencephaly who developed retroflexion of the holosphere 7 years after a ventriculo-peritoneal shunt was placed. The radiological findings revealed retroflexion of the cerebrum anchored to the cranial vault between the precerebral space and the dorsal sac, which were open to each other. In patients with holoprosencephaly, the possibility of retroflexion of the holosphere should be considered after placement of a ventriculo-peritoneal shunt for associated hydrocephalus.

Influence of forage species and diet particle size on the passage of digesta and nylon particles from the reticulorumen of steers

To assess factors that influence the passage of digesta from the reticulorumen, ruminally fistulated steers (387 kg) were fed to appetite in a 4 x 4 Latin square design either orchardgrass (OG) (Dactylis glomerata L.) or switchgrass (SG) (Panicum virgatum L.) hays. The two hays were fed in either the long form or ground to pass a 2-cm screen. Steers fed OG diets had greater DMI (P < .05) than steers fed SG diets (11.7 vs 10.4 kg/d respectively). Particle size of ruminal digesta and feces determined by wet sieving was greater (P < .05) for the OG and long hay diets than for the SG and ground diets. Particle size of digesta collected from the anterior dorsal sac and anterior ventral sac of the rumen and from the reticulum did not vary (P > .25) with site. Conversely, ruminal concentrations of 1-mm nylon particles tended (P = .11) to be greater in the lower strata of the reticulorumen at 12 and 24 h after dosing. Neither a site effect nor a site x time-after-dosing interaction (P > .75) was observed for the 3- or 5-mm nylon particles, suggesting that a sorting process independent of specific gravity occurs in the rumen for smaller particles (before the reticulomasal orifice). Passage rate of the 1-mm nylon particles from the reticulorumen was greater (P < .01) for animals fed the SG than for those fed the OG diets, whereas for the 5-mm particles, passage rate was greater for the OG diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascularization of the pineal complex in the lizard Tiliqua rugosa

The vascularization of the pineal complex in the lizard Tiliqua rugosa was investigated by vascular corrosion and latex casting techniques. The fine structure of the pineal capillaries was also studied by transmission electron microscopy. The pineal complex in T. rugosa consists of an elongated pineal gland proper and a separate, distinct parietal eye. The pineal complex derives an abundant blood supply from branches of the middle and posterior cerebral arteries. Scanning electron microscopy of vascular corrosion casts revealed a dense and extensive pineal capillary bed which drains ultimately into a wide longitudinal sinus suggesting an efficient pathway for the rapid removal of substances secreted by the gland. The parietal eye, which receives a unilateral left-sided blood supply from the unpaired anterior pineal artery, is shown to be a highly vascularized structure. The close morphological relationship between the pineal gland and dorsal sac, where the two structures apparently share the same blood vessels, suggests a functional relationship between them. The pineal capillaries are fenestrated with tight junctions between adjoining endothelial cells. Podia-like abluminal extensions of the endothelial cells were observed in close relation to unmyelinated nerve bundles. The basal margin of the pineal parenchyma is highly invaginated with thin finger-like cytoplasmic protrusions into the pericapillary space. Distinct bands of microfibrils form "struts" anchoring the pineal parenchyma to the endothelial wall. These features may have a role in the transfer of materials between the pineal gland and the blood stream.