Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Origin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,117 records · Page 62Linked to original sources
PubMed1999

Anatomical variations in the origin of the human ophthalmic artery with special reference to the cavernous sinus and surrounding meninges.

The origin of the human ophthalmic artery (OA) and surrounding structures was investigated in 109 cadavers by three different methods: macroscopic, stereomicroscopic, and histological observations. The following results were obtained. (1) Macroscopic observation: In 39% of the specimens the origin of the OA was observable in the cranial cavity and defined as the intradural (i.d.) type. The other 61% were named the extradural (e.d.) type. (2) Stereomicroscopic observation: In 59% of the cases, the OA originated from the internal carotid artery over or on the cavernous roof and at least a part of the OA was exposed within the cranial cavity. In the other 41% the OA originated within the cavernous wall or cavity and entered directly the optic dural sheath, thus no part of the OA was visible in the cranial cavity. Therefore, approximately 20% of the origins of the OA might be of the i.d. type, although they could not be macroscopically identified in the cranial cavity since they might emanate from the internal carotid artery between the optic canal and the optic nerve, even above the cavernous roof. (3) Histological observation: The proximal portion of the OA runs alongside the optic nerve within the subarachnoid space in the cases of the i.d. type. In contrast, the corresponding portion of the e.d. type was embedded in the dense fibrous tissue which was continuous both with the dura mater of the cavernous wall and the periosteum of the sphenoid. These anatomical data may provide important information for understanding the variety of the pathology in this region and is also useful for designing operative strategies.

Adolescent↗
PubMed2003

A study on the activation peptide released from procarboxypeptidase B (CAPAP) and anionic trypsinogen in patients with acute abdominal disorders of non-pancreatic origin.

BACKGROUND: The activation peptide released from procarboxypeptidase B, CAPAP, is a marker of the activation of pancreatic enzymes in acute pancreatitis while anionic trypsinogen (AT) levels in urine relate to leakage of unactivated proenzymes. Data on these markers in patients suffering from severe acute abdominal disorders of non-pancreatic origin are lacking. PURPOSE: To examine levels of CAPAP and AT in serum and urine from patients with severe acute abdominal disorders of non-pancreatic origin in order to better define the diagnostic specificity of these two markers in severe acute pancreatitis in relation to other acute intra-abdominal disorders. SUBJECTS AND METHODS: The study included 54 patients with severe acute abdominal disorders of non-pancreatic origin with an APACHE II score >3. Immunoreactive CAPAP (irCAPAP) and immunoreactive AT (irAT) were measured in serum and urine using specific immunoassays. RESULTS: In urine, irCAPAP levels were mildly increased (>2 nmol/l) in 13% of the patients with severe acute abdominal diseases of non-pancreatic origin, but on no occasion did the increase approach the cutoff levels described for severe acute pancreatitis (>100 nmol/l). However, irAT levels in serum and urine were increased (>50 micro g/l) in 54% of the cases. CONCLUSION: Contrary to what is found for irAT, patients with acute abdominal pain of non-pancreatic origin rarely have markedly increased levels of irCAPAP in serum and urine.

Abdominal Pain↗
PubMed2005

Diagnostic criteria in predicting a biliary origin of acute pancreatitis in the era of endoscopic ultrasound: multicentre prospective evaluation of 213 patients.

BACKGROUND: No study on bioclinical criteria predicting a biliary origin for acute pancreatitis has included endosonography as a reference examination. Re-examination of bioclinical parameters deserves consideration in the era where other causes are known (e.g. hereditary, autoimmune). AIM AND METHODS: To determine the performance of bioclinical markers in predicting a biliary origin of acute pancreatitis where the diagnosis of biliary lithiasis was established or ruled out using endosonography. Only patients with a first acute episode of pancreatitis were included. RESULTS: 213 patients (male: 55%; median age: 56 years) were prospectively included in 14 centres. Causes of acute pancreatitis were: biliary (62%), alcoholic (25%), other (13%). Delay between symptom-onset and admission was <48 h in 80%. Endosonography was the sole method establishing the diagnosis of biliary pancreatitis in 15% of patients. At univariate analysis, age, female sex, declared alcohol consumption, elevated aspartate and alanine transaminases on admission, gammaglutamyl transferase, alkaline phosphatase, total bilirubin, lipase, mean corpuscular volume were predictive of a biliary origin. Only age (p < 0.0001), sex (p < 0.0008) and alanine transaminase (p < 0.0004) remained significant at multivariate analysis. At age 50, the respective sensitivity and specificity were 73 and 65%. With an elevated alanine transaminase at 2 times the upper limit of normal range, the respective sensitivity and specificity were 74 and 84%. The probability of a biliary origin of acute pancreatitis could be estimated by the following formula: = 1/1 + exp(4.6967 - 0.0656 x age + 1.1208 x sex - 0.6909 x alanine transaminase). CONCLUSION: When endosonography is performed to confirm or exclude a biliary origin of acute pancreatitis, age, sex and alanine transaminase at admission are the only factors predictive of a biliary cause.

Acute Disease↗
PubMed2006

Malagasy primate origins: phylogenies, fossils, and biogeographic reconstructions.

The geographic origin of Malagasy primates is a rich source of debate, providing a useful context for understanding effects of differing phylogenetic interpretations upon area of origin reconstructions. This study has evaluated the biogeographic implications of competing primate phylogenies in order to reconstruct the area of origin of Malagasy strepsirhines. The robusticity of biogeographic inference is examined based on sensitivity to tree topology. The results demonstrate extreme vulnerability to both out-group choice and internal tree topology, suggesting caution for area of origin interpretations from phylogenies that exclude fossil taxa. Moreover, even a single taxon can have a powerful effect upon biogeographic interpretations. Perhaps not surprisingly, it is only with greater phylogenetic resolution that a clearer understanding of the biogeographic origins of Malagasy primates will emerge.

Animals↗
PubMed1977

Origin of triploidy and tetraploidy in man: 11 cases with chromosomes markers.

Sixteen triploid and one tetraploid human abortuses were studied for the origin of polyploidy using a sequential Q- and R-banding technique. Ten triploid abortuses provided informative data: one originated in the maternal first meiotic division; five apparently resulted from dispermy; two derived from an error during either the paternal second meiotic division or the first mitotic division; and the last two were of paternal origin. The results indicate that paternal factors, especially dispermy, are the predominant sources of triploidy in man. The tetraploid abortus showed duplication of both the maternal and paternal haploid sets, suggesting normal division of chromosomes and suppression of cytoplasmic cleavage at the first mitotic division. No correlation was found between the origin of polyploidy and the phenotype of the triploid abortuses, nor between the origin of polyploidy and the maternal use of oral contraceptives.

Abortion, Spontaneous↗
PubMed2004

Geographic origin as a determinant of carotid artery intima-media thickness and brachial artery flow-mediated dilation: the Cardiovascular Risk in Young Finns study.

OBJECTIVE: People living in eastern Finland have approximately 40% higher coronary heart disease mortality rates than western Finns. Whether this is because of genetic or environmental factors is unknown. We examined the effect of geographic family origin on subclinical atherosclerosis among young Finns. METHODS AND RESULTS: As part of a longitudinal follow-up study, we measured carotid intima-media thickness (IMT) in 2264 and brachial flow-mediated dilation (FMD) in 2109 white adults, aged 24 to 39 years. Subjects from eastern Finland had greater IMT and lower FMD compared with western subjects. These differences accentuated when the subjects' family origin (grandparents' birthplace) was taken into account and remained significant after adjusting for several environmental factors. Among subjects with all grandparents born in eastern or western Finland, IMTs were (mean+/-SEM) 0.592+/-0.003 versus 0.565+/-0.005 mm (P<0.0001), respectively. The corresponding FMD values were 7.61+/-0.15% versus 8.75+/-0.26%; P<0.01. The number of grandparents born in eastern Finland was directly related to IMT (P<0.0001) and inversely to FMD (P<0.05). CONCLUSIONS: Young adults originating from eastern Finland have greater carotid IMT and lower brachial FMD than western Finns. Consistent with a hereditable component predisposing to or protecting from atherosclerosis, these differences accentuated when subjects' family origin was taken into account. We studied whether an east-west difference exists in markers of subclinical atherosclerosis in 2264 Finns aged 24 to 39 years. Subjects with family origin in eastern Finland had greater carotid IMT and lower brachial FMD compared with western subjects, suggesting that hereditable factors play a role in excess atherosclerosis risk in eastern Finland.

Adult↗
PubMed2002

Cardiomyocytes of noncardiac origin in myocardial biopsies of human transplanted hearts.

BACKGROUND: Cell replacement therapy with stem cells able to differentiate into cardiomyocytes has been discussed as a method for remodeling damaged myocardium. A physiological or pathophysiological situation in which this phenomenon might be relevant is not known. We studied the origin of cardiomyocytes in myocardial biopsies of male patients that had undergone sex-mismatched cardiac transplantation to determine whether cells containing a Y chromosome (and therefore being of recipient origin) are able to differentiate into cardiomyocytes. METHODS AND RESULTS: Myocardial biopsies (n=21) were obtained from the right ventricles of male patients (n=13) who had undergone sex-mismatched heart transplantation. Tissue from 1 nontransplanted male and myocardial biopsies from sex-matched heart-transplanted patients served as controls. Cells from donor and recipient origins were identified by fluorescence in situ hybridization with the use of specific probes for X and Y chromosomes on paraffin sections of the biopsies. Cell types were identified by using immunostaining procedures on the same tissue sections. Cardiomyocytes of recipient origin were detected in 8 of 13 male recipients of female hearts. They were connected by gap junctions with adjacent myocytes. Of the cardiomyocyte nuclei, 0.16+/-0.04% (mean+/-SEM, median 0.09%) contained the Y-chromosomal marker. There was no detectable correlation with the extent or number of rejection episodes, time of transplantation, or medical treatment regimen. CONCLUSIONS: These results show that regeneration by cells of noncardiac origin (differentiated into cardiomyocytes and physiologically linked to neighboring myocytes) can be detected even in small myocardial biopsies. This may lead to new diagnostic and therapeutic strategies in the treatment of myocardial infarction, inflammatory heart disease, and/or heart failure.

Biopsy↗
PubMed2004

Electrocardiographic recognition of the epicardial origin of ventricular tachycardias.

BACKGROUND: Some ventricular tachycardias (VTs) originating from the epicardium are not suitable for endocardial radiofrequency ablation and require an epicardial approach. The aim of this study was to define the ECG characteristics that may identify an epicardial origin of VTs. METHODS AND RESULTS: We analyzed the 12-lead ECG recordings during epicardial and endocardial left ventricular pacing in 9 patients to verify the hypothesis that the epicardial origin of the ventricular activation widens the initial part of the QRS complex. Then, we analyzed the ECG pattern in 14 VTs successfully ablated from the epicardium after a failed endocardial approach (group A), in 27 VTs successfully ablated from the endocardium (group B), and in 28 additional VTs that could not be ablated from the endocardium (group C). Four distinct intervals of ventricular activation were defined and measured: (1) the pseudodelta wave, (2) the intrinsicoid deflection time in V2, (3) the shortest RS complex, and (4) the QRS complex. VTs from groups A and C showed a significantly longer pseudodelta wave, intrinsicoid deflection time, and RS complex duration compared with VTs of group B. There was no difference between groups A and C. A pseudodelta wave of > or =34 ms has a sensitivity of 83% and a specificity of 95%, an intrinsicoid deflection time of > or =85 ms has a sensitivity of 87% and a specificity of 90%, and an RS complex duration of > or =121 ms has a sensitivity of 76% and a specificity of 85% in identifying an epicardial origin of the VTs. CONCLUSIONS: ECG suggests VTs originating from the epicardium and those with an unsuccessful radiofrequency ablation from the endocardium.

Cardiac Pacing, Artificial↗
PubMed2004

Risk of intracerebral hemorrhage in patients with arterial versus cardiac origin of cerebral ischemia on aspirin or placebo: analysis of individual patient data from 9 trials.

BACKGROUND AND PURPOSE: Patients who are anticoagulated after cerebral ischemia have a 19-fold-higher risk of intracerebral hemorrhage (ICH) if they had an arterial rather than a cardiac source. To determine whether this excess risk of ICH was due to the underlying disease (cerebral ischemia of arterial versus cardiac origin) or whether it depended on the antithrombotic regimen, we studied the risk of ICH in arterial versus cardiac origin of cerebral ischemia in patients who received aspirin or no antithrombotic drugs. METHODS: Individual patient data of patients who received aspirin or placebo after cerebral ischemia were obtained from 9 clinical trials. Presence of atrial fibrillation was considered evidence of a cardiac source. Otherwise, events were considered of arterial origin. Cox proportional-hazards modeling was used for univariate and multivariate analyses. RESULTS: Fifty-four ICHs occurred in 16 625 patient-years in the aspirin-treated patients, and 7 ICHs occurred in 4317 patient-years in those on placebo. After multivariate adjustment for age, sex, current smoking, history of hypertension and diabetes, and aspirin dose (aspirin-treated patients only), the hazard ratio for ICH in patients with an arterial versus a cardiac source was 0.74 (95% confidence interval, 0.30 to 1.82) for aspirin-treated patients and 4.34 (95% confidence interval, 0.35 to 54) for placebo-randomized patients. CONCLUSIONS: Our findings do not confirm the previous finding of an excess risk of ICH in patients with cerebral ischemia of arterial origin. Therefore, it seems that having cerebral ischemia of arterial origin by itself is not associated with an increased risk of ICH, but only in combination with high-intensity anticoagulation.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Evaluation of the original Ontario Child Health Study scales.

This article presents evaluative information on the use of the original Ontario Child Health Study scales to serve as original-level measures of conduct disorder, hyperactivity and emotional disorder among children in the general (non clinic) population. Problem checklist assessments were obtained from parents and teachers of children aged six to 16 and youth aged 12 to 16 drawn from a general population (n = 1,751); and a mental health clinic sample (n = 1,027) in the same industrialized, urban setting. The results showed that the original OCHS scales possess adequate psychometric properties to be used as original-level measures of disorder. Correlations between individual items and their hypothesized scales were very strong, indicating convergent validity, while correlations between the same items and other (non hypothesized) scales were lower, indicating discriminant validity. Item analyses indicated that individual scale items possess both convergent and discriminant validity. Although the scales were skewed to the positive end of the continuum, they demonstrated good internal consistency (all estimates > or = 0.74) and test-retest (all estimates > or = 0.65) reliability. Finally, three different validity analyses confirmed hypotheses about how the original OCHS scales should perform if they provide useful measures of disorder.

Adolescent↗
PubMed2003

Formation of trisomies and their parental origin in hyperdiploid childhood acute lymphoblastic leukemia.

High hyperdiploidy, common in childhood acute lymphoblastic leukemia (ALL) with a favorable prognosis, is characterized by specific trisomies. Virtually nothing is known about its formation or pathogenetic impact. We evaluated 10 patients with ALL using 38 microsatellite markers mapped to 18 of the 24 human chromosomes to investigate the mechanisms underlying hyperdiploidy and to ascertain the parental origin of the trisomies. Based on the results, doubling of a near-haploid clone and polyploidization with subsequent losses of chromosomes could be excluded. The finding of equal allele dosage for tetrasomy 21 suggests that hyperdiploidy originates in a single aberrant mitosis, though a sequential gain of chromosomes other than 21 in consecutive cell divisions remains a possibility. Our study, the first to address experimentally the parental origin of trisomies in ALL, revealed no preferential duplication of maternally or paternally inherited copies of X, 4, 6, 9, 10, 17, 18, and 21. Trisomy 8 was of paternal origin in 4 of 4 patients (P =.125), and +14 was of maternal origin in 7 of 8 patients (P =.0703). Thus, the present results indicate that imprinting is not pathogenetically important in hyperdiploid childhood ALL, with the possible exception of the observed parental skewness of +8 and +14.

Adolescent↗
PubMed2005

Precision and type I error rate in the presence of genotype errors and missing parental data: a comparison between the original transmission disequilibrium test (TDT) and TDTae statistics.

BACKGROUND: Two factors impacting robustness of the original transmission disequilibrium test (TDT) are: i) missing parental genotypes and ii) undetected genotype errors. While it is known that independently these factors can inflate false-positive rates for the original TDT, no study has considered either the joint impact of these factors on false-positive rates or the precision score of TDT statistics regarding these factors. By precision score, we mean the absolute difference between disease gene position and the position of markers whose TDT statistic exceeds some threshold. METHODS: We apply our transmission disequilibrium test allowing for errors (TDTae) and the original TDT to phenotype and modified single-nucleotide polymorphism genotype simulation data from Genetic Analysis Workshop. We modify genotype data by randomly introducing genotype errors and removing a percentage of parental genotype data. We compute empirical distributions of each statistic's precision score for a chromosome harboring a simulated disease locus. We also consider inflation in type I error by studying markers on a chromosome harboring no disease locus. RESULTS: The TDTae shows median precision scores of approximately 13 cM, 2 cM, 0 cM, and 0 cM at the 5%, 1%, 0.1%, and 0.01% significance levels, respectively. By contrast, the original TDT shows median precision scores of approximately 23 cM, 21 cM, 15 cM, and 7 cM at the corresponding significance levels, respectively. For null chromosomes, the original TDT falsely rejects the null hypothesis for 28.8%, 14.8%, 5.4%, and 1.7% at the 5%, 1%, 0.1% and 0.01%, significance levels, respectively, while TDTae maintains the correct false-positive rate. CONCLUSION: Because missing parental genotypes and undetected genotype errors are unknown to the investigator, but are expected to be increasingly prevalent in multilocus datasets, we strongly recommend TDTae methods as a standard procedure, particularly where stricter significance levels are required.

Chromosomes, Human, Pair 3↗
PubMed2005

The effect of cartilage and bone density of mushroom-shaped, photooxidized, osteochondral transplants: an experimental study on graft performance in sheep using transplants originating from different species.

BACKGROUND: Differences in overall performance of osteochondral photooxidized grafts were studied in accordance of their species origin and a new, more rigorous cleansing procedure using alcohol during preparation. METHODS: Photooxidized mushroom-shaped grafts of bovine, ovine, human and equine origin were implanted in the femoral condyles of 32 sheep (condyles: n = 64). No viable chondrocytes were present at the time of implantation. Grafts were evaluated at 6 months using plastic embedded sections of non-decalcified bone and cartilage specimens. Graft incorporation, the formation of cyst-like lesions at the base of the cartilage junction as well as cartilage morphology was studied qualitatively, semi-quantitatively using a score system and quantitatively by performing histomorphometrical measurements of percentage of bone and fibrous tissue of the original defects. For statistical analysis a factorial analysis of variance (ANOVA- test) was applied. RESULTS: Differences of graft performance were found according to species origin and cleansing process during graft preparation. According to the score system cartilage surface integrity was best for equine grafts, as well as dislocation or mechanical stability. The equine grafts showed the highest percentage for bone and lowest for fibrous tissue, resp. cystic lesions. The new, more rigorous cleansing process decreased cartilage persistence and overall graft performance. CONCLUSION: Performance of grafts from equine origin was better compared to bovine, ovine and human grafts. The exact reason for this difference was not proven in the current study, but could be related to differences in density of cartilage and subchondral bone between species.

Animals↗
PubMed1980

Scales measuring people's perception of themselves as origins and pawns.

Scales measuring people's perception of themselves as origins (determining their own behavior) or pawns (their behavior being determined by forces beyond their control) were devised using content analysis of verbalizations. Scoring categories were based on the work of Heider (1955). Reliability was satisfactory. Normative data were obtained from 528 people, each experiencing one of nine life situations. Pawn and origin perception differed across situations and these differences were correlated with independent ratings of how people would perceive the situations. Pawn perception was more stable over time than origin perception but both varied over time. Origin scores were relatively independent of measures of negative affect. Pawn scores were associated with hostility directed inward, ambivalent hostility and total anxiety. Associations were found with some forms of Coping behavior and people's reactions to a relative's serious or less serious illness. Origin and pawn scores were not negatively correlated, indicating the inappropriateness of regarding them as opposite ends of a single dimension of causal perception.

Journal Article↗
PubMed2006

Clinical significance of the parental origin of the X chromosome in turner syndrome.

CONTEXT: The phenotype in Turner syndrome (TS) is variable, even in patients with a supposedly nonmosaic karyotype. Previous work suggested that there were X-linked parent-of-origin effects on the phenotype. HYPOTHESIS: The TS phenotype is influenced by the parental origin of the missed X chromosome. DESIGN: This was a multicenter prospective study of TS patients and both their parents, determining parental origin of the X-chromosome, and characterizing the clinical phenotype. PATIENTS AND METHODS: Eighty-three TS patients and their parents were studied. Inclusion criteria were TS with karyotype 45,X or 46Xi(Xq). Four highly polymorphic microsatellite markers on the X-chromosome DMD49, DYSII, DXS1283, and the androgen receptor gene and three Y chromosome markers, SRY, DYZ1, and DYZ3. OUTCOME MEASURES: The study determined the correlation between the parental origin of the X chromosome and the unique phenotypic traits of TS including congenital malformations, anthropometry and growth pattern, skeletal defects, endocrine traits, education, and vocation. RESULTS: Eighty-three percent of 45,X retained their maternal X (X(m)), whereas 64% 46Xi(Xq) retained their paternal X (X(p), P < 0.001). Kidney malformations were exclusively found in X(m) patients (P = 0.030). The X(m) group had lower total and low-density lipoprotein cholesterol (P < 0.003), and higher body mass index sd score (P = 0.030) that was not maintained after GH treatment. Response to GH therapy was comparable. Ocular abnormalities were more common in the paternal X group (P = 0.017), who also had higher academic achievement. CONCLUSIONS: The parental origin of the missing short arm of the X chromosome has an impact on overweight, kidney, eye, and lipids, which suggests a potential effect of an as-yet-undetermined X chromosome gene imprinting.

Adolescent↗
PubMed2005

Surgical anatomy of the ophthalmic artery: its origin and proximal course.

OBJECTIVE: We examined the surgical anatomy of the ophthalmic artery (OA) by dissection of cadaver heads, evaluating the anatomic relationships between the origin of the OA and both its proximal course and surrounding structures. In addition, we demonstrated the surgical application of these anatomic features for safe surgical exploration of this region. METHODS: Through anatomic dissection, the origin of the OA was examined in both sides of 25 formalin-fixed and 10 fresh cadaver specimens. The following parameters were evaluated: the location of the origin of the OA in relation to the dural rings, the topographic relationship of the paraclinoid region, and the location of the dural penetrating point of the OA in the optic canal. RESULTS: The OA originated from the internal carotid artery within the intradural space in 49% of cases, just above the upper dural ring in 37%, at the clinoid segment in 7%, and within the cavernous sinus in 6%. The dural penetrating point of the OA was anterior to the falciform ligament, and thereby in the optic canal, in 74% of cases, ventral to the falciform ligament in 19%, and posterior to the falciform ligament in 7%. The anterior circumference point of the upper dural ring, the point at which the upper dural ring intersects the anterior edge of the internal carotid artery, was more anterior to the falciform ligament in 40% of cases and ventral and posterior to the falciform ligament in 16.4% and 43.6%, respectively. CONCLUSION: Our anatomic findings demonstrate anatomic variation of the OA in terms of its region of origin. Several anatomic points that were noteworthy during surgical exploration of this region are discussed.

Cadaver↗
PubMed1993

The triple origin of skull in higher vertebrates: a study in quail-chick chimeras.

We have used the quail-chick chimera technique to study the origin of the bones of the skull in the avian embryo. Although the contribution of the neural crest to the facial and visceral skeleton had been established previously, the origin of the vault of the skull (i.e. frontal and parietal bones) remained uncertain. Moreover formation of the occipito-otic region from either the somitic or the cephalic paraxial mesoderm had not been experimentally investigated. The data obtained in the present and previous works now allow us to assign a precise embryonic origin from either the mesectoderm, the paraxial cephalic mesoderm or the five first somites, to all the bones forming the avian skull. We distinguish a skull located in front of the extreme tip of the notochord which reaches the sella turcica and a skull located caudally to this boundary. The former ('prechordal skull') is derived entirely from the neural crest, the latter from the mesoderm (cephalic or somitic) in its ventromedial part ('chordal skull') and from the crest for the parietal bone and for part of the otic region. An important point enlighten in this work concerns the double origin of the corpus of the sphenoid in which basipresphenoid is of neural crest origin and the basipostsphenoid is formed by the cephalic mesoderm. Formation of the occipito-otic region of the skeleton is particularly complex and involves the cooperation of the five first somites and the paraxial mesoderm at the hind-brain level. The morphogenetic movements leading to the initial puzzle assembly could be visualized in a reproducible way by means of small grafts of quail mesodermal areas into chick embryos. The data reported here are discussed in the evolutionary context of the 'New Head' hypothesis of Gans and Northcutt (1983, Science, 220, 268-274).

Animals↗
PubMed1987

The specificity of motor innervation of the chick wing does not depend upon the segmental origin of muscles.

In vertebrate embryos, motor axons originating from a particular craniocaudal position in the neural tube innervate limb muscles derived from myoblasts of the same segmental level. We have investigated whether this relationship is important for the formation of specific nerve-muscle connections, by altering the segmental origin of muscles and examining their resulting innervation. First, by grafting quail wing somites to a new craniocaudal position opposite the chick wing, we established that the segmental origin of a muscle can be altered: presumptive muscle cells migrated according to their new, rather than their original, somitic level, colonizing a different subset of muscles. However, after reversal of a length of brachial somitic mesoderm along the craniocaudal axis, or exchange or shift of brachial somites, the craniocaudal position of wing muscle motoneurone pools within the spinal cord was undisturbed, despite the new segmental origin of the muscles themselves. While not excluding the possibility that muscles and their motor nerves are labelled segmentally, we conclude that specific motor axon guidance in the wing does not depend upon the existence of such labels.

Animals↗