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D G Thomas

Publications and source records attributed to D G Thomas.

At least 19 recordsLinked to original sources
PubMed2006

Pattern formation in Taylor-Couette flow of dilute polymer solutions: dynamical simulations and mechanism.

We report spatiotemporal pattern formation in Taylor-Couette flow (i.e., flow between rotating cylinders) of viscoelastic dilute polymer solutions obtained for the first time from first-principles dynamical simulations. Solution structures with varying spatial and temporal symmetries, such as rotating standing waves, flames, disordered oscillations, and solitary vortex solutions which include diwhirls (stationary and axisymmetric) and oscillatory strips (axisymmetric or nonaxisymmetric), are observed, depending on the ratio of fluid relaxation time to the time period of inner cylinder rotation. The flow-microstructure coupling mechanisms underlying the pattern formation process are also discussed.

Journal Article↗
PubMed2006

Genomic amplification of MET with boundaries within fragile site FRA7G and upregulation of MET pathways in esophageal adenocarcinoma.

Esophageal adenocarcinoma (EA) is characterized by a poor prognosis making the identification of clinically targetable proteins essential for improving patient outcome. We report the involvement of multiple alterations of the MET pathway in EA development and progression. Microarray analysis of Barrett's metaplasia, dysplasia, and EA revealed overexpression of the MET oncogene in EAs but only those with MET gene amplification. STS-amplification mapping revealed that the boundary of the MET amplicon in these EAs is defined by fragile site FRA7G. We also identified an amplicon at 11p13 that resulted in amplification and overexpression of CD44, a gene involved in MET autophosphorylation upon HGF stimulation. Tissue microarrays with phospho-MET-specific antibodies demonstrated a uniformly high abundance of MET activation in primary EA and cells metastatic to lymph nodes but to a lesser extent in a subset of metaplastic and dysplastic Barrett's samples. Increased expression of multiple genes in the MET pathway associated with invasive growth, for example, many MMPs and osteopontin, also was found in EAs. Treatment of EA-derived cell lines with geldanamycin, an inhibitor for tyrosine kinases including MET receptor kinase, reduced cell migration and induced EA cell apoptosis. The data indicate that upregulation of the MET pathway may contribute to the poor outcome of EA patients and that therapeutic agents targeting this pathway may help improve patient survival.

Adenocarcinoma↗
PubMed2005

Spirometra erinacei / S. erinaceieuropaei in a feral cat in Manawatu with chronic intermittent diarrhoea.

CASE HISTORY: A feral cat captured in the Manawatu region of New Zealand was treated for worms and fleas, and kept confined in a metabolic cage. It showed good appetite and weight gain but had intermittent watery, yellow diarrhoea. CLINICAL FINDINGS: Clinical examination under sedation was unremarkable and routine blood tests showed no significant abnormalities. The cat was negative for feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV). Different canned cat foods did not alter the course of the diarrhoea, and the cat was euthanised 6 months after capture. At necropsy, two sections of adult Spirometra tapeworms were found in the jejunum and typical Spirometra eggs were found in colonic contents. Molecular identification of the parasite was undertaken, using the cytochrome-c oxidase subunit-1 gene (cox1) sequence. DIAGNOSIS: Chronic intermittent diarrhoea associated with Spirometra erinacei / S. erinaceieuropaei infection. CLINICAL RELEVANCE: Spirometra has not been reported in New Zealand before but has been associated with gastrointestinal disease in cats in other parts of the world. It requires species targeted treatment to be eliminated effectively, and is zoonotic. Diagnosis could be difficult for clinicians who are not familiar with the parasite and its life cycle.

Animals↗
PubMed2004

Influence of phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digestive tract measurements and gut morphology in broilers fed wheat-based diets containing adequate level of phosphorus.

1. The aim of the present study was to examine the influence of microbial phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digesta viscosity, digestive tract measurements and gut morphology in broilers fed on wheat-soy diets containing adequate phosphorus (P). The wheat-soy basal diet was formulated to contain 4.5 g/kg non-phytate P and the experimental diets were formulated by supplementing the basal diet with xylanase (1000 xylanase units/kg diet), phytase (500 phytase units/kg diet) or a combination of phytase and xylanase. 2. Supplemental phytase improved the weight gains and feed efficiency by 17.5 and 2.9%, respectively. Corresponding improvements due to the addition of xylanase were 16.5 and 4.9%, respectively. The combination of phytase and xylanase caused no further improvements in broiler performance. 3. Individual additions of xylanase or phytase resulted in numerical improvements in apparent metabolisable energy (AME), but the differences were not significant. The combination of the two enzymes significantly increased AME. Addition of xylanase and the combination of the two enzymes reduced the viscosity of digesta in all sections of the intestine. Phytase supplementation reduced digesta viscosity in the duodenum and ileum, but not in the jejunum. 4. Enzyme supplementation lowered the relative weight and length of the small intestine. Additions of xylanase and phytase reduced the relative weight of the small intestine by 15.5 and 11.4%, respectively, while the corresponding reductions in the relative length of the small intestine were 16.5 and 14.1%, respectively. The combination of phytase and xylanase had no further effects on the relative weight and length of the small intestine compared with the xylanase group. 5. The addition of phytase increased villus height in the duodenum and decreased the number of goblet cells in the jejunum compared with those on the unsupplemented basal diet. Xylanase supplementation tended to increase goblet cell numbers in the duodenum and decreased crypt depth in thejejunum. The combination of phytase and xylanase increased villus height in the ileum and crypt depth in thejejunum and ileum. 6. In summary, the present results showed that the addition of a microbial phytase, produced by solid state fermentation and containing significant activities of beta-glucanase and xylanase, was as effective as xylanase in improving the performance of broiler chickens fed on wheat-based diets containing adequate levels of P. Improved performance with enzyme supplementation was generally associated with reduced digesta viscosity, increased AME, and reduced relative weight and length of small intestine.

6-Phytase↗
PubMed2004

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers.

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.

Animal Nutritional Physiological Phenomena↗
PubMed2004

Influence of stocking density on the performance, carcass characteristics and selected welfare indicators of broiler chickens.

AIM: To compare the effects of four stocking densities (5, 10, 15 or 20 birds per m2) on the performance, carcass characteristics and selected welfare indicators of broiler chickens. METHODS: A total of 756 day-old male broiler chicks were assigned as six replicates of 13, 25, 38 and 50 birds per pen, to stocking densities of 2,000, 1,000, 667 and 500 cm2 floor space per bird, respectively. The birds were housed in floor pens in an environmentally controlled room. Normal commercial diets were fed ad libitum and fresh water was freely available throughout the 5-week study period. Liveweights of birds and feed intake were recorded at weekly intervals. Data on carcass parameters and welfare indicators (moisture, gait scores, feather scores, breast and hip lesions, and foot pad and hock burns) were obtained on Day 35. Adrenal glands were removed at slaughter, weighed and examined histologically to determine the total proportion of cortical and medullary tissues. RESULTS: During the study, the birds at the lowest density grew faster (p<0.001-0.01) and consumed more (p<0.001- 0.01) feed than those at the other three stocking densities. The liveweight gains and feed intake of birds reared at densities of 10, 15 and 20 birds per m2 were similar (p=0.11-0.83 and p=0.17-0.57, respectively). Stocking density had no influence on the feed/weight gain, mortality or carcass characteristics. No breast or hip lesions were observed in carcasses from any of the groups. The weight and structure of the adrenal glands were similar across all groups although the staining of medullary tissue of birds was most intense in the highest stocking density group. As stocking density increased, so did moisture and gait score, hock and foot pad burn scores, and the feather score was adversely affected. CONCLUSIONS: The data showed that the relationship between stocking density and productivity traits was not linear in nature, in accordance with other studies. Under the conditions of the current study, the performance, mortality and carcass characteristics of broilers grown at densities of 10, 15 and 20 birds per m2 were similar. There were some welfare implications at high population densities as indicated by adverse effects on litter quality, gait scores and the incidence of hock and foot pad burns.

Journal Article↗
PubMed2002

Magnetic resonance urography in patients with neurogenic bladder dysfunction and spinal dysraphism.

OBJECTIVE: To investigate the reliability of magnetic resonance urography (MRU) using heavily T2-weighted very fast spin-echo sequences in imaging the upper urinary tract in patients with spinal dysraphism and neuropathic bladder dysfunction. PATIENTS AND METHODS: Patients with neuropathic bladder dysfunction secondary to spinal dysraphism may have gross spinal deformity, which makes assessing the urinary tract extremely difficult by ultrasonography or intravenous urography. The study included 50 patients (median age 33 years, range 19-52) with a median (range) Cobb's angle of 60 (0-240) degrees. No contrast medium was given but all patients received 20 mg of intramuscular frusemide 20-30 min before MRU. RESULTS: Thirty-five patients had previous ultrasonography, during which only 42 kidneys and no ureters were visible. Of the 94 renal tracts, MRU visualized all kidneys and 86 (89%) ureters. There was good agreement amongst observers on assessing the kidneys and pelvicalyceal systems (kappa > or = 0.61) but only moderate agreement on evaluating the ureters (kappa < or = 0.61). There was disagreement on normality vs renal parenchymal scarring in 14 (15%) kidneys, about no dilatation vs dilatation of the pelvicalyceal system in 14 (15%) systems and about no dilatation vs dilatation of the ureter in 20 (22%) ureters. The overall quality of the MRU images was rated highly, with a mean (range) score of 4.6 (3-5). CONCLUSION: MRU provides a reliable noninvasive technique for imaging the upper tract in patients who were previously difficult to investigate.

Adult↗
PubMed2001

Gain of 1q and loss of 22 are the most common changes detected by comparative genomic hybridisation in paediatric ependymoma.

Ependymomas are the third most common brain tumour in the paediatric population. Although cytogenetic and molecular analyses have pinpointed deletions of chromosomes 6q, 17, and 22 in a subset of tumours, definitive patterns of genetic aberrations have not been determined. In the present study, we analysed 40 ependymomas from paediatric patients for genomic loss or gain using comparative genomic hybridisation (CGH). Eighteen of the tumours (45%) had no detectable regions of imbalance. In the remaining cases, the most common copy number aberrations were loss of 22 (25% of tumours) and gain of 1q (20%). Three regions of high copy number amplification were noted at 1q24-31 (three cases), 8q21-23 (two cases), and 9p (one case). Although there was no association with the loss or gain of any chromosome arm or with benign versus anaplastic histologic characteristics, the incidence of gain of 7q and 9p and loss of 17 and 22 was significantly higher in recurrent versus primary tumours. This study has identified a number of chromosomal regions that may contain candidate genes involved in the development of different subgroups of ependymoma.

Adolescent↗
PubMed2001

In-hospital mortality from abdominal aortic surgery in Great Britain and Ireland: Vascular Anaesthesia Society audit.

BACKGROUND: The mortality rate associated with elective aortic aneurysm repair is widely assumed to be in the region of 5 per cent. This figure does not take into consideration the effect of pre-existing risk factors. The Vascular Anaesthesia Society of Great Britain and Ireland conducted a large audit to estimate the in-hospital mortality rate associated with non-emergency infrarenal aortic surgery throughout the British Isles, and to determine the influence of risk factors on mortality rate. METHODS: This was a multicentre, prospective audit of 177 hospitals throughout the UK and Ireland. Data were collected by questionnaire to include all patients undergoing elective or urgent surgery for infrarenal abdominal aortic aneurysm or aortoiliac occlusive disease over 4 months. RESULTS: Nine hundred and thirty-three patients were recruited into the audit. The overall mortality rate was 7.3 per cent. Factors increasing the risk of death by up to fivefold included age over 74 years, urgent surgery, operation for occlusive disease, limited exercise capacity, a history of severe angina or cardiac failure, the presence of ventricular ectopics and abnormalities suggesting ischaemic heart disease on electrocardiography. CONCLUSION: Although the in-hospital mortality rate was similar to previously published figures, the rate increased considerably when commonly encountered risk factors were present.

Adult↗
PubMed2001

Interactive image-guided transcallosal microsurgery for anterior third ventricular cysts.

Although the treatment of colloid cysts remains controversial, high viscosity and small volume are poor prognostic indicators for successful burr hole aspiration and cortical incision via craniotomy may be associated with postoperative epilepsy. The anterior transcallosal approach provides a direct and adequate pathway to the lateral ventricles, where the foramen of Monro serves as a natural entrance into the anterior third ventricle, especially when the foramen is dilated by a lesion. When the midsuperior portion of the IIIrd ventricle cannot be reached, the interforniceal or the subchoroidal exposures have been advocated. Stereotactic techniques contribute to a minimal invasive approach and reduce morbidity. Nine patients harbouring anterior third ventricular cysts (seven colloids and two intrinsic craniopharyngiomas) underwent anterior transcallosal microsurgical excision assisted by an interactive infrared-based image guided system (EasyGuide, Neuro, Philips). There were 4 men and 5 women ranging in age from 15 to 42 years (mean 28.5). Transcallosal transforaminal (5 cases) or interforniceal (4 cases) approaches allowed total excision in eight patients and subtotal in one. Postoperative morbidity included a case of transient hemiparesis and a case of transient short-term memory disturbances; both resolved in the first months. Mortality was zero. Particular advantages of the method were accurate trajectory and position of callosotomy incision determination, visualisation and avoidance of superior saggital sinus, retraction of bridging veins and the often variable pericallosal arteries, spatial orientation within the ventricular system, and identification of the periventricular anatomical structures.

Adolescent↗
PubMed2001

Response of short-term cultures derived from human malignant glioma to aziridinylbenzoquinone, etoposide and doxorubicin: an in vitro phase II trial.

The relative resistance of malignant glioma to chemotherapy makes the identification of new cytotoxic drugs critically important. The use of short-term cultures derived from these tumors to screen drugs at doses that can be attained within human intracranial tumors provides a model system that should be capable of identifying effective drugs suitable for clinical evaluation. The sensitivity of a panel of short-term cultures derived from 22 malignant astrocytoma and four malignant oligodendroglioma was assessed to aziridinylbenzoquinone (AZQ), etoposide and doxorubicin (DOX) using a [(35)S] methione uptake assay. The ID(50) of each culture was compared to the levels of drug which could be achieved in the tumor using standard doses. There was marked heterogeneity between cultures in response to each drug. Whilst there was no evidence that cultures derived from grade III astrocytoma were more sensitive to any of the drugs than cultures derived from grade IV astrocytoma, cultures derived from oligodendroglioma tended to be more sensitive to the alkylating agent AZQ, but not to either of the other drugs. The sensitivity of these short-term cultures at concentrations that can be achieved in situ corresponded well with the clinical efficacy of AZQ and etoposide. Although DOX appeared to be toxic to human gliomas cells in vitro, its limited penetration into the intact brain would seem to preclude its use i.v., but it is likely to be effective if local drug delivery techniques could be employed. The study suggests that short-term cultures derived from malignant glioma should be used to screen investigational agents for potential clinical efficacy.

Antineoplastic Agents↗
PubMed2001

Clinical validation of true frameless stereotactic biopsy: analysis of the first 125 consecutive cases.

OBJECTIVE: A lockable guide device, adjustable for positioning, was used to obtain samples for tissue analysis during brain biopsy procedures performed using an interactive image guidance system. Clinical validation of this technique, which was developed for true frameless stereotactic biopsies, and analyses of the histological yield, complication rate, and patient demographic characteristics for a large series of frameless stereotactic biopsies were the purposes of this study. METHODS: Demographic, radiological, surgical, and clinical data were prospectively collected for a series of 125 frameless stereotactic biopsies performed using the technique described in detail previously. RESULTS: Eighty-six procedures were magnetic resonance imaging-directed and 39 were computed tomography-directed. The mean diameter of the biopsied lesions was 36 mm, and the mean distance from the skin was 35.8 mm. Sixteen percent of the patients harbored multiple lesions, and 5.6% of the biopsied lesions were infratentorial. The mean operative time (including the entire anesthetic time) was 1.5 hours. The smear examination findings were corroborated by conclusive histological results in 96% of the cases, and definitive positive diagnoses were obtained in 122 cases (97.6%). Ten patients experienced surgical complications, but the sustained morbidity rate was 2.4% (including the death of a patient who was in critical clinical condition preoperatively and who died 2 mo later as a result of a chest infection; mortality rate, 0.8%). CONCLUSION: This true frameless stereotactic biopsy technique was associated with low morbidity and mortality rates and an excellent diagnostic yield, with overall results at least as good as those observed for frame-based stereotaxy. The excellent accuracy results demonstrated previously and statistically significant reductions in operative time, as well as improved image presentation, target selection, and simplicity, support the use of this frameless stereotactic technique in preference to frame-based biopsy techniques.

Adult↗
PubMed2000

Firing patterns of pallidal cells in parkinsonian patients correlate with their pre-pallidotomy clinical scores.

It is unclear how the disordered activity of cells in the basal ganglia contributes to the symptoms of Parkinson's disease (PD). We recorded from single neurons extracellularly in 3 regions of the globus pallidus (GPe, GPie and GPii) in patients undergoing pallidotomy for PD. Movement-related cell firing patterns, analysed using hidden Markov models, were significantly correlated with patients' preoperative clinical scores (off drugs). Responses of cells in GPii correlated best with the scores for specific motor tasks, rather than general ones related to activities of daily living, but the reverse was true for responses from GPe. In both GPii and GPe, a higher score (i.e. greater parkinsonian severity) was associated with greater variability in cell firing rather than an increase in firing rate itself.

Activities of Daily Living↗
PubMed2000

Benign central neurocytoma.

BACKGROUND: "Central neurocytoma" is classically considered as an intraventricular benign tumor, largely based on data from small retrospective series. The authors present prospective data on 12 patients with tumors diagnosed as central neurocytoma, to highlight the diverse nature of this tumor and challenge the classic notion. METHODS: Between 1991 and 1997, 12 patients had tumors diagnosed prospectively as "central neurocytoma". Clinical, radiologic, and histologic data were collected, and Karnofsky performance score was evaluated for each patient. Proliferation marker studies were performed using Ki-67 labeling index. RESULTS: In two patients, the tumors were located in atypical locations, namely, the parietal lobe and the spine. Aggressive behavior characterized by clinical and radiologic evidence of tumor progression was noted in two additional patients. In both these cases, unusually high proliferation rates of 5.3% and 11.2% were noted. Total excision of the tumor, when possible, was the treatment of choice. Postoperative radiotherapy to the residual tumor may be of benefit in patients with clinically aggressive tumors, or those with high proliferation rates. CONCLUSIONS: Given the findings of this study, it is suggested that the traditional concept of central neurocytoma as a benign intraventricular tumor warrants reconsideration.

Adolescent↗
PubMed2000

Chemosensitivity in childhood brain tumours in vitro: evidence of differential sensitivity to lomustine (CCNU) and vincristine.

The aim of this study was to examine the range of sensitivity of a panel of short-term cultures derived from different types of malignant childhood brain tumours including medulloblastoma, ependymoma and glioblastoma multiforme to three cytotoxic drugs, lomustine (CCNU), vincristine (VCR) and procarbazine (PCB). Sensitivity was assessed using a modification of the dimethylthiazolyl-2,5-diphenyl tetrazolium bromide (MTT) assay. Short-term cell lines derived from ependymomas were considerably more resistant to VCR than other types of childhood brain tumours, while cultures derived from supratentorial primitive neuroectodermal tumour (PNET) displayed marked sensitivity to both lomustine and VCR. Cultures from ependymomas, medulloblastoma and astrocytic gliomas had similar sensitivity to lomustine and PCB as cultures derived from adult malignant astrocytoma.

Adult↗
PubMed2000

Evaluation of techniques for lignocaine hydrochloride analgesia of the velvet antler of adult stags.

AIM: To evaluate the effectiveness of various routes of administration and doses of local anaesthetic (LA) to provide analgesia of the velvet antler of adult stags. METHODS: In Experiment 1, antlers from 50 red deer stags, >or=2-years-old were allocated to 1 of 4 treatment groups (n = 25 antlers/group) to receive injections with 2% lignocaine hydrochloride as follows: High-dose (1 ml/cm pedicle circumference) or Low-dose ring-block (0.4 ml/cm pedicle circumference) or; High-site or Low-site regional nerve block (5 ml per site, both of which included the auriculopalpebral nerve). An electrical stimulus was applied before application of LA and then each min for up to 4 min after LA injection. If no response was observed, analgesia was tested with a saw cut. If no response occurred, the antler was cut at that time. If the animal responded, a further wait time was applied until 4 min had elapsed, at which time observations ceased. In Experiment 2, 10 primary and 50 re-growth antlers were given a High-dose ring-block and tested with a saw cut after 1 min (n = 30) or 2 min (n = 30). If no response occurred, the antler was removed. If a response occurred, further 1-min wait periods were applied. RESULTS: In the High-dose ring-block and High-site nerve-block groups, 24/25 and 21/25 antlers were removed without response by 2 min, compared with 20/25 and 15/25 antlers in the Low-dose ring-block and Low-site nerve-block groups, respectively. The High-dose ring-block provided more effective analgesia after 3 min than the Low-dose ring-block, as assessed by the number of stags that did not respond to the electrical stimulus (p = 0.008), or subsequent antler removal (p = 0.050). The numbers of antlers removed without response after 1 or 2 min were greater using the High-site nerve-block than the Low-site nerve-block (p = 0.002 and p = 0.037, respectively). In all but the High-dose ring-block group, at least 1 stag required further LA after 4 min, before antler could be humanely removed. In Experiment 2, stags reacted to a saw-cut test on 6/30 antlers, 1 min after a High-dose ring-block, compared with 1/30 antlers after 2 min (p = 0.051). CONCLUSION: The High-dose ring-block produced the most effective and rapid analgesia. CLINICAL RELEVANCE: A High-dose ring-block with a 2-min wait period should be the preferred method for achieving local analgesia for velvet antler removal.

Journal Article↗
PubMed2000

Spinal neurenteric cysts without associated malformations. Are they the same as those presenting in spinal dysraphism?

Spinal neurenteric cysts are rare intradural developmental lesions, usually composed of a thin-walled cyst whose lining mimicks gastro-intestinal or respiratory epithelium. A detailed review of the literature revealed 80 cases of solitary spinal neurenteric cysts (including a new case of ours), which were analysed and compared, regarding clinical and pathological aspects, with 56 such cases of those with concomitant evidence of dysraphism. Older age and cervical location were found to be statistically characteristic of the solitary cysts in contrast to younger age and lumbosarcal location for the 'dysraphic' cases. Magnetic resonance imaging is the diagnostic modality of choice. Good evidence of the developmental origin of incomplete separation of notochord and endoderm was given by the fact that histologically solitary cysts were mainly composed by endodermal derivatives, while 'dysraphic' had also mesenchymal and ectodermal elements. Thus, it seems that additional spinal dysraphic changes are more likely to be found when ectodermal and mesenchymal elements co-exist with endodermal ones, possibly indicating an earlier error in development than in other cases containing only endodermal elements.

Humans↗