Notochordal cells: A potential therapeutic option for intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a prevalent musculoskeletal degenerative disorder worldwide, and ~40% of chronic low back pain cases are associated with IDD. Although the pathogenesis of IDD remains unclear, the reduction in nucleus pulposus cells (NPCs) and degradation of the extracellular matrix (ECM) are critical factors contributing to IDD. Notochordal cells (NCs), derived from the notochord, which rapidly degrades after birth and is eventually replaced by NPCs, play a crucial role in maintaining ECM homeostasis and preventing NPCs apoptosis. Current treatments for IDD only provide symptomatic relief, while lacking the ability to inhibit or reverse its progression. However, NCs and their secretions possess anti-inflammatory properties and promote NPCs proliferation, leading to ECM formation. Therefore, in recent years, NCs therapy targeting the underlying cause of IDD has emerged as a novel treatment strategy. This article provides a comprehensive review of the latest research progress on NCs for IDD, covering their biological characteristics, specific markers, possible mechanisms involved in IDD and therapeutic effects. It also highlights significant future directions in this field to facilitate further exploration of the pathogenesis of IDD and the development of new therapies based on NCs strategies.

Chordoma concurrent with benign notochordal cell tumor of the mobile spine. Should the chordoma part be biopsied? - A stepwise approach for management

Some evidence suggests that benign notochordal tumors (BNCTs) could be a potential precursor of chordoma. We present an educational rare case of lumbar vertebral BNCTs concomitant with a destructive lesion not reachable on biopsy but thought to be chordoma. We present a stepwise approach for management of these difficult entities based on radiological features.

Ecchordosis physaliphora presenting as hypnic headache

Ecchordosis physaliphora (EP) is a rare benign congenital hamartomatous lesion originating from remnants of the notochord. EP has never been associated with hypnic headache before. We report for the first time two cases of EP associated with an hypnic headache. The latter is a form of sleep-related nocturnal headache whose pathogenesis has not been fully elucidated. A 61-year-old woman and a 41-year-old man had been complaining of a dull headache that woke them up every night for many months. In both cases, an enlarged cystic lesion in the prepontine cistern, compatible with ecchordosis physaliphora, was found on brain MRI. A diagnosis of hypnic headache secondary to EP was made. Ecchordosis physaliphora presenting as hypnic headache had never been described before. The low prevalence of both conditions (EP and HH) and their presence in two cases might suggest a possible causal association between the two conditions.

Ecchordosis Physaliphora: Does It Even Exist?

The term ecchordosis physaliphora (EP) has been used historically to describe a benign notochordal remnant with no growth potential, most commonly occuring in the central clivus. Unfortunately, the radiologic appearance of EP overlaps considerably with the appearance of low-grade chordomas, which do have the potential for growth. In this article, we review new pathologic terminology that better describes this family of diseases, and we propose new radiologic terms that better address the uncertainty of the radiologic diagnosis. The surgical importance of accurate terminology and the implications for patient care are discussed.

Possible notochordal chordoma in a fossil fish from the Late Cretaceous of Lebanon

OBJECTIVE

To describe a case of an expansive endocavitary lesion at the level of the caudal tract of the vertebral column of a juvenile fish (Pycnodont) from the Late Cretaceous (Cenomanian) of Lebanon (Hjoula).

MATERIALS

The specimen is part of the Paleontological Collection of the University Museum of Chieti, Italy, Inventory Number P #23752.

METHODS

The specimen was observed macroscopically, as well as under the stereo-microscope (Leica Wild M 8); aspersion with ethanol and razing light were used to improve the observations and to take micro-photos.

RESULTS

The fossil juvenile fish has a visibly altered macroscopic anatomical morphology at the level of the caudal part of the vertebral column, which is pathological in comparison with the normal anatomy of the Pycnodonts.

CONCLUSIONS

Although diagnosis cannot be certain, comparative analysis notes morphological and topographic affinity between the paleopathological case described here and notochordal chordoma, which affects some living fish.

SIGNIFICANCE

This lesion represents the first case of a nonosseous tumor in a fossil fish, and suggests that this type of neoplasm was among the first of the neoplastic diseases to appear on Earth.

LIMITATIONS

Diagnosis rendered from fossil remains is complex and is further limited by the rarity of the condition in the past.

SUGGESTIONS FOR FURTHER RESEARCH

Continued comparative analysis of bony changes noted in this specimen with other fossil and living fish will contribute to our understanding of disease in the Earth's earliest inhabitants.

Developmental neurotoxicity of maneb: Notochord defects, mitochondrial dysfunction and hypoactivity in zebrafish (Danio rerio) embryos and larvae

Broad applications and exposure to the fungicide maneb can lead to toxicity in non-target organisms. Maneb is also associated with neurogenerative diseases such as Parkinson's disease (PD). The objectives of this study were to determine the acute toxicity of maneb to zebrafish by measuring mitochondrial bioenergetics, locomotor activity, and the expression of genes related to the oxidative damage response, as well as those related to dopamine signaling due to its association with PD. Zebrafish embryos at 6 h post-fertilization (hpf) were exposed to either solvent control (0.1% DMSO, v/v), or one dose of 0.1, 0.5, 1.0 and 10.0 µM maneb for 96 h. Maneb was moderately toxic to zebrafish embryos, and had a 96-h LC₅₀ value of 4.29 μM (~ 1.14 mg/L). Maneb induced a dose-dependent increase in mortality, decreased hatching rate, and increased notochord deformity rate at both 1.0 and 10.0 µM after 72 and 96 h. Total body length was also significantly reduced with 1.0 µM maneb. A 50-60% decrease in mean basal oxygen consumption rate was also observed in embryos following a 24 hpf exposure to 10.0 µM maneb but oligomycin-induced ATP production and FCCP-induced maximum respiration remained unaffected. No change was detected in the expression levels of genes associated with oxidative stress (sod1 and sod2), nor those related to dopamine synthesis (th1), dopamine transporter (dat), dopamine receptors (drd1, drd2a, drd3, and drd4b). Thus, modifying the expression of these transcripts may not be a mechanism for maneb-induced developmental toxicity in zebrafish. To assess the potential for neurotoxicity, a dark photokinesis assay was conducted in larvae following 7 d exposure to 0.1, 0.5 and 1.0 μM maneb. Larvae exposed to 0.5 and 1.0 μM maneb showed signs related to hypoactivity, and this reduced activity is hypothesized to be associated with notochord defects as this deformity was prevalent at higher concentrations of maneb. Overall, these data demonstrate that maneb negatively affects embryonic development (i.e. notochord development), affects basal oxygen consumption rates of embryos, and induces hypoactivity in larval fish. This study improves understanding regarding the developmental neurotoxicity of the fungicide maneb to zebrafish.

Loss of Type I Collagen Telopeptide Lysyl Hydroxylation Causes Musculoskeletal Abnormalities in a Zebrafish Model of Bruck Syndrome

Bruck syndrome (BS) is a disorder characterized by joint flexion contractures and skeletal dysplasia that shows strong clinical overlap with the brittle bone disease osteogenesis imperfecta (OI). BS is caused by biallelic mutations in either the FKBP10 or the PLOD2 gene. PLOD2 encodes the lysyl hydroxylase 2 (LH2) enzyme, which is responsible for the hydroxylation of lysine residues in fibrillar collagen telopeptides. This hydroxylation directs crosslinking of collagen fibrils in the extracellular matrix, which is necessary to provide stability and tensile integrity to the collagen fibrils. To further elucidate the function of LH2 in vertebrate skeletal development, we created a zebrafish model harboring a homozygous plod2 nonsense mutation resulting in reduced telopeptide hydroxylation and crosslinking of bone type I collagen. Adult plod2 mutants present with a shortened body axis and severe skeletal abnormalities with evidence of bone fragility and fractures. The vertebral column of plod2 mutants is short and scoliotic with compressed vertebrae that show excessive bone formation at the vertebral end plates, and increased tissue mineral density in the vertebral centra. The muscle fibers of mutant zebrafish have a reduced diameter near the horizontal myoseptum. The endomysium, a layer of connective tissue ensheathing the individual muscle fibers, is enlarged. Transmission electron microscopy of mutant vertebral bone shows type I collagen fibrils that are less organized with loss of the typical plywood-like structure. In conclusion, plod2 mutant zebrafish show molecular and tissue abnormalities in the musculoskeletal system that are concordant with clinical findings in BS patients. Therefore, the plod2 zebrafish mutant is a promising model for the elucidation of the underlying pathogenetic mechanisms leading to BS and the development of novel therapeutic avenues in this syndrome. © 2016 American Society for Bone and Mineral Research.

[Benign notochordal cell tumor of cervical vertebrae: a clinicopathologic analysis]

OBJECTIVE

To report 2 rare cases of benign notochordal cell tumor (BNCT), according to WHO classification of tumors of soft tissue and bone (4th edition). Their radiologic and clincopathologic features and differential diagnosis were investigated.

METHODS

Two cases of BNCT were studied by retrospective review of the clinical, radiologic, pathologic and immunophenotypical findings. Related literatures were reviewed at the same time.

RESULTS

Case 1 was a 53-year-old man, and case 2 was a 61-year-old woman. Radiographically, both patients presented with abnormal imaging findings in the fifth cervical vertebral body with the lesions located within the bone but without extra osseous mass. Histopathologically, the lesions lacked lobular architecture and extracellular myxoid matrix. The tumor cells were vacuolated and had centrally or peripherally placed round or oval nuclei with small nucleoli, mimicking mature adipocytes. No cytological atypia or mitotic figures were seen. The affected bone trabeculae were sclerotic and islands of bone marrow were often entrapped within the tumor.

CONCLUSIONS

Although sharing similar anatomic distribution and immunophenotype to those of chordoma, BNCT has distinct radiologic and pathologic features and different treatment and prognosis. The differential diagnosis between BNCT and chordoma requires detailed clinical, radiologic and histopathologic evaluations.

Benign notochordal cell tumor: a retrospective study of 11 cases with 13 vertebra bodies

PURPOSE

To analyze the clinical data, MRI, pathological diagnosis, treatment and long-term effects of benign notochordal cell tumor (BNCT), a newly described novel spine tumor.

METHODS

We retrospectively studied 11 patients' clinical data of the above.

RESULTS

The ratio of males to females was 4:7, and the average age was 49.2 years (range, 18-74 years). Cervical vertebra (5; 38.5%) and thoracic vertebra (5; 38.5%) were the most frequent site followed by the lumbar vertebra (3; 23%). Pain was the main symptom except case 2 who were diagnosed accidently because of prostate cancer. The mean delay from first clinical symptoms to diagnosis was ranged from 2 months to 20 years. MRI showed all BNCTs were osteolytic lesions with hypointense on T1-weighted sequences, hyperintense on T2-weighted sequences. There were 4 vertebral bodies with wedge fracture. There were two cases that had two noncontiguous vertebral bodies with BNCT. In histology, marrow replacement was noted by multivacuolated physaliphorous cells immunoreactive for CK, EMA and S100 protein. All 10 cases except case 2 had vertebral reconstruction and fixation with different methods. Of the 11 patients, 9 had full follow-up data which showed no evidence of recurrence or metastasis without further treatment.

CONCLUSION

Noncontiguous multi-centricity BNCTs are rare. No specific vertebrae are more frequently involved. Once BNCT is diagnosed by pathology, the surgical intervention is necessary for the patients with obvious clinical symptoms although it is benign. There is no evidence of BNCT recurrence or metastasis.

The effects of the toxic cyanobacterium Limnothrix (strain AC0243) on Bufo marinus larvae

Limnothrix (strain AC0243) is a cyanobacterium, which has only recently been identified as toxin producing. Under laboratory conditions, Bufo marinus larvae were exposed to 100,000 cells mL(-1) of Limnothrix (strain AC0243) live cultures for seven days. Histological examinations were conducted post mortem and revealed damage to the notochord, eyes, brain, liver, kidney, pancreas, gastrointestinal tract, and heart. The histopathological results highlight the toxicological impact of this strain, particularly during developmental stages. Toxicological similarities to β-N-Methylamino-L-alanine are discussed.

High glucose-induced oxidative stress promotes autophagy through mitochondrial damage in rat notochordal cells

PURPOSE

Diabetes mellitus is associated with an increased risk of intervertebral disc degeneration (IDD). Reactive oxygen species (ROS), oxidative stressors, play a key role in autophagy of diabetes-associated diseases. Mitochondria are known to be the main source of endogenous ROS in most mammalian cell types. The authors therefore conducted the following study to evaluate the effects of high glucose concentrations on the induction of oxidative stress and autophagy through mitochondrial damage in rat notochordal cells.

METHODS

Rat notochordal cells were isolated, cultured, and placed in either 10% fetal bovine serum (normal control) or 10% fetal bovine serum plus two different high glucose concentrations (0.1 M and 0.2 M) (experimental conditions) for one and three days, respectively. We identified and quantified the mitochondrial damage (mitochondrial transmembrane potential) and the generation of ROS and antioxidants (manganese superoxide dismutase [MnSOD] and catalase). We also investigated expressions and activities of autophagy markers (beclin-1, light chain3-I [LC3-I] and LC3-II, autophagy-related gene [Atg] 3, 5, 7, and 12).

RESULTS

An enhanced disruption of mitochondrial transmembrane potential, which indicates mitochondrial damage, was identified in rat notochordal cells treated with both high glucose concentrations. Both high glucose concentrations increased production of ROS by rat notochordal cells in a dose- and time-dependent manner. The two high glucose solutions also enhanced rat notochordal cells' compensatory expressions of MnSOD and catalase in a dose- and time-dependent manner. The proautophagic effects of high glucose concentrations were manifested in the form of enhanced rat notochordal cells' expressions of beclin-1, LC3-II, Atg3, 5, 7, and 12 in a dose- and time-dependent manner. The ratio of LC3-II/LC3-I expression was also increased in a dose- and time-dependent manner.

CONCLUSIONS

The findings from this study demonstrate that high glucose-induced oxidative stress promotes autophagy through mitochondrial damage of rat notochordal cells in a dose- and time-dependent manner. These results suggest that preventing the generation of oxidative stress might be a novel therapeutic target by which to prevent or to delay IDD in patients with diabetes mellitus.

An integrated functional genomics approach identifies the regulatory network directed by brachyury (T) in chordoma

Chordoma is a rare malignant tumour of bone, the molecular marker of which is the expression of the transcription factor, brachyury. Having recently demonstrated that silencing brachyury induces growth arrest in a chordoma cell line, we now seek to identify its downstream target genes. Here we use an integrated functional genomics approach involving shRNA-mediated brachyury knockdown, gene expression microarray, ChIP-seq experiments, and bioinformatics analysis to achieve this goal. We confirm that the T-box binding motif of human brachyury is identical to that found in mouse, Xenopus, and zebrafish development, and that brachyury acts primarily as an activator of transcription. Using human chordoma samples for validation purposes, we show that brachyury binds 99 direct targets and indirectly influences the expression of 64 other genes, thereby acting as a master regulator of an elaborate oncogenic transcriptional network encompassing diverse signalling pathways including components of the cell cycle, and extracellular matrix components. Given the wide repertoire of its active binding and the relative specific localization of brachyury to the tumour cells, we propose that an RNA interference-based gene therapy approach is a plausible therapeutic avenue worthy of investigation.

Abnormal notochord branching is associated with foregut malformations in the adriamycin treated mouse model

Oesophageal atresia (OA) and tracheooesophageal fistula (TOF) are relatively common human congenital malformations of the foregut where the oesophagus does not connect with the stomach and there is an abnormal connection between the stomach and the respiratory tract. They require immediate corrective surgery and have an impact on the future health of the individual. These abnormalities are mimicked by exposure of rat and mouse embryos in utero to the drug adriamycin. The causes of OA/TOF during human development are not known, however a number of mouse mutants where different signalling pathways are directly affected, show similar abnormalities, implicating multiple and complex signalling mechanisms. The similarities in developmental outcome seen in human infants and in the adriamycin treated mouse model underline the potential of this model to unravel the early embryological events and further our understanding of the processes disturbed, leading to such abnormalities. Here we report a systematic study of the foregut and adjacent tissues in embryos treated with adriamycin at E7 and E8 and analysed between E9 and E12, comparing morphology in 3D in 149 specimens. We describe a spectrum of 8 defects, the most common of which is ventral displacement and branching of the notochord (in 94% of embryos at E10) and a close spatial correspondence between the site of notochord branching and defects of the foregut. In addition gene expression analysis shows altered dorso-ventral foregut patterning in the vicinity of notochord branches. This study shows a number of features of the adriamycin mouse model not previously reported, implicates the notochord as a primary site of disturbance in such abnormalities and underlines the importance of the model to further address the mechanistic basis of foregut congenital abnormalities.

A novel zebrafish mutant with wavy-notochord: an effective biological index for monitoring the copper pollution of water from natural resources

We identified a novel zebrafish mutant that has wavy-notochord phenotypes, such as severely twisted notochord and posterior malformations, but has normal melanocytes. Histological evidences showed that proliferating vacuolar cells extended their growth to the muscle region, and consequently caused the wavy-notochord phenotypes. Interestingly, those malformations can be greatly reversed by exposure with copper, suggesting that copper plays an important role on wavy-notochord phenotypes. In addition, after long-term copper exposure, the surviving larvae derived from wavy-notochord mutants displayed bone malformations, such as twisted axial skeleton and osteophyte. These phenotypic changes and molecular evidences of wavy-notochord mutants are highly similar to those embryos whose lysyl oxidases activities have been inactivated. Taken together, we propose that (i) the putative mutated genes of this wavy-notochord mutant might be highly associated with the lysyl oxidase genes in zebrafish; and (ii) this fish model is an effective tool for monitoring copper pollution of water from natural resources.

Primary extranotochordal cervical chordoma masquerading as a thyroid neoplasm: a case report

BACKGROUND

Chordoma is a rare malignant neoplasm of notochord origin that occurs along the craniospinal axis, and extranotochordal chordoma is extremely unusual. An aberrant origin of this neoplasm can pose diagnostic pitfalls. We report a case of primary cervical chordoma of extranotochordal origin clinically presenting as a thyroid neoplasm. The cytomorphologic features of chordoma and its cytologic differential diagnoses are discussed.

CASE

An 82-year-old man presented with hoarseness of voice and difficulty in swallowing. He had a mass in the anterolateral aspect of the right side of the neck. Magnetic resonance imaging of the neck with contrast study revealed an ill-defined, contrast-enhancing tumor mass located in the right retrolaryngeal and parapharyngeal space at the level of C4, invading the perithyroidal soft tissue. Aspiration biopsy cytology of the tumor demonstrated epithelial-like cells with varied cytomorphologic features causing differential diagnostic problems with thyroid and soft tissue. However, the diagnosis of extranotochordal chordoma was established by the subsequent histologic examination of the excisional biopsy specimen.

CONCLUSION

Since chordoma is capable of exhibiting a spectrum of cytomorphologic characteristics and can have cytologic features overlapping with other malignant neoplasms, a high index of suspicion is crucial to make an accurate diagnosis on fine needle aspiration biopsy. This case highlights the occurrence of a rare neoplasm at an aberrant site and the diagnostic challenges that can pose. However, awareness of the abnormal locations and characteristic cytomorphologic features of chordoma together with radiologic findings will usually keep the cytopathologist from making a wrong diagnosis.

Evaluation of pyridoacridine alkaloids in a zebrafish phenotypic assay

Three new minor components, the pyridoacridine alkaloids 1-hydroxy-deoxyamphimedine (1), 3-hydroxy-deoxyamphimedine (2), debromopetrosamine (3), and three known compounds, amphimedine (4), neoamphimedine (5) and deoxyamphimedine (6), have been isolated from the sponge Xestospongia cf. carbonaria, collected in Palau. Structures were assigned on the basis of extensive 1D and 2D NMR studies as well as analysis by HRESIMS. Compounds 1–6 were evaluated in a zebrafish phenotype-based assay. Amphimedine (4) was the only compound that caused a phenotype in zebrafish embryos at 30 μM. No phenotype other than death was observed for compounds 1–3, 5, 6.

Persistent notochordal canal imitating compression fracture--plain film, CT and MR appearance

BACKGROUND

Persistent notochordal canal is a rare developmental anomaly, typically restricted to 1 or 2 vertebral levels, and only in exceptional cases extending over a longer segment. It is usually asymptomatic and discovered incidentally.

CASE REPORT

A 30-year-old woman reported to our department for control lumbar spine plain films. About 2 years before, after minor trauma, she had been misdiagnosed on radiograms in another hospital as having a compression L5 vertebra fracture. The assessment of current plain films and analysis of previous radiograms delivered indicated the need for taking a developmental anomaly into consideration. Based on CT and MR of lumbar spine performed, a final diagnosis of a persistent notochordal canal was established.

CONCLUSIONS

In spite of its rare occurrence, the characteristic features of a persistent notochordal canal should be known by radiologists, particularly to avoid misinterpretation in post-traumatic patients.

Structural requirements for PACSIN/Syndapin operation during zebrafish embryonic notochord development

PACSIN/Syndapin proteins are membrane-active scaffolds that participate in endocytosis. The structure of the Drosophila Syndapin N-terminal EFC domain reveals a crescent shaped antiparallel dimer with a high affinity for phosphoinositides and a unique membrane-inserting prong upon the concave surface. Combined structural, biochemical and reverse genetic approaches in zebrafish define an important role for Syndapin orthologue, Pacsin3, in the early formation of the notochord during embryonic development. In pacsin3-morphant embryos, midline convergence of notochord precursors is defective as axial mesodermal cells fail to polarize, migrate and differentiate properly. The pacsin3 morphant phenotype of a stunted body axis and contorted trunk is rescued by ectopic expression of Drosophila Syndapin, and depends critically on both the prong that protrudes from the surface of the bowed Syndapin EFC domain and the ability of the antiparallel dimer to bind tightly to phosphoinositides. Our data confirm linkage between directional migration, endocytosis and cell specification during embryonic morphogenesis and highlight a key role for Pacsin3 in this coupling in the notochord.

A case of ecchordosis physaliphora presenting with an intratumoral hemorrhage

Ecchordosis physaliphora is a rare congenital, benign, hamartomatous, retroclival mass derived from notochordal tissue that is typically located intradurally in the prepontine cistern. Ecchordosis physaliphora is usually asymptomatic. In rare cases, ecchordosis physaliphora can be symptomatic due to tumor expansion and compression of the surrounding structures and extratumoral hemorrhage. To our knowledge, ecchordosis physaliphora associated with intratumoral hemorrhage and vasogenic edema has not been previously described. We present a case of 22-year-old man who presented with headache and confusion. MR imaging and CT revealed intracranial ecchordosis physaliphora associated with intratumoral hemorrhage and vasogenic edema. The neurological findings resolved completely after medical therapy.

Intraosseous Benign Notochord Cell Tumors (BNCT): Further Evidence Supporting a Relationship to Chordoma

BACKGROUND

Previous studies have documented the existence of intraosseous benign notochordal cell tumors (BNCTs) within the axial skeleton. Evidence suggests that they may be associated with the development of chordomas. To further investigate the relationship between BNCT and classic chordoma, we reviewed a large series of resected sacral/coccygeal chordomas in an attempt to identify the presence of coexisting BNCTs.

DESIGN

Eighty-two sacrectomy/coccygectomy specimens performed for chordoma were identified. Available hematoxylin and eosin slides were reviewed to identify BNCTs and assess their relationship with the coexisting chordoma. BNCTs were defined, in accordance with prior descriptions, as cohesive aggregates of large cells that appeared adipocyte-like because of their vacuolated cytoplasm. The cells exhibited only minimal nuclear atypia and lacked lobulation and myxoid stroma.

RESULTS

We identified 6 BNCTs, each was adjacent to but separate from the sacral chordoma. There were 5 females and 1 male, and the mean age was 58 years. Five lesions arose in the sacrum. One lesion arose in the coccyx, and involved 2 contiguous vertebral levels. The BNCTs ranged in size from 1 to 20 mm with a mean size of 6.1 mm. The lesions were exclusively composed of adipocyte-like nuclei without significant nuclear atypia or myxoid stroma. Three lesions contained sclerotic bony trabeculae and intralesional hematopoietic elements were identified in 1 case. In all cases the chordoma was of the conventional type and were morphologically different from the BNCT.

CONCLUSIONS

BNCTs were identified in 7.3% of sacral/coccygeal resections performed for primary chordoma. We speculate that this finding provides further evidence that BNCT is the precursor lesion for chordoma. Additional investigations are needed to further understand this relationship.

Overexpressions of nerve growth factor and its tropomyosin-related kinase A receptor on chordoma cells

STUDY DESIGN

Immunohistochemistry and in situ apoptosis detection assay were performed on chordoma and notochordal cells.

OBJECTIVES

To investigate the expression levels of nerve growth factor (NGF) and its 2 receptors, tropomyosin-related kinase A (TrkA) and p75, as well as proliferation potential and apoptosis indexes in chordoma and notochordal cells.

SUMMARY OF BACKGROUND DATA

Chordomas arise from primitive notochordal remnants. Why these notochordal remnants undergo malignant transformation to chordoma remains unknown. The binding of NGF to the TrkA receptor promotes cell survival, while its binding to the p75 receptor triggers apoptosis. If there is simultaneous expression of both receptors, the effect of TrkA supersedes and the cells survive.

METHODS

We examined 10 surgically obtained sacral chordoma tissue samples to determine the expressions of NGF and TrkA and p75 receptors as well as markers of cellular proliferation and apoptosis. As controls, we used notochordal cells of L4-L5 discs obtained from ten 1-month old rats. We quantified the expressions of NGF and TrkA and p75 receptors as well as markers of cellular proliferation and apoptosis for both groups, respectively.

RESULTS

Chordoma and notochordal cells both expressed NGF as well as TrkA and p75 receptors. While the mean percentage of p75 receptor expression was very similar between chordoma and notochordal cells (P = 0.394), the mean percentages of TrkA and NGF expressions were significantly higher in chordoma cells than in notochordal cells (both P = 0.002). The mean proliferation potential index of chordoma cells was significantly higher than in notochordal cells (P < 0.01). Conversely, the mean apoptosis index of chordoma cells was significantly lower compared with that of notochordal cells (P = 0.03).

CONCLUSION

The current results suggest that increased expressions of NGF and TrkA receptor in chordoma cells might be a possible mechanism of malignant transformation of notochordal remnants to chordoma by negating apoptotic signal of p75 receptor.

Aberrant Bmp signaling and notochord delamination in the pathogenesis of esophageal atresia

Human foregut malformation known as esophageal atresia with tracheoesophageal fistula (EA/TEF) occurs in 1 in 4,000 live births with unknown etiology. We found that mice lacking Noggin (Nog(-/-)) displayed Type C EA/TEF, the most common form in humans, and notochordal defects strikingly similar to the adriamycin-induced rat EA/TEF model. In accord with esophageal atresia, Nog(-/-) embryos displayed reduction in the dorsal foregut endoderm, which was associated with reduced adhesion and disrupted basement membrane. However, significant apoptosis in the Nog(-/-) dorsal foregut was not observed. Instead, non-notochordal, likely endodermal, cells were found in Nog(-/-) notochord, suggesting that Noggin function is required in the notochordal plate for its proper delamination from the dorsal foregut. Notably, ablating Bmp7 function in Nog(-/-) embryos rescued EA/TEF and notochord branching defects, establishing a critical role of Noggin-mediated Bmp7 antagonism in EA/TEF pathogenesis.

Coccydynia due to a benign notochordal cell tumor

STUDY DESIGN

Case report.

OBJECTIVE

To present a rare case of a notochordal cell tumor.

SUMMARY OF BACKGROUND DATA

We report on a 27-year-old female patient with pain at the lower back and muscle cramps in the area of the right hip. Image studies demonstrated a cystic lesion of the coccyx.

METHODS

As clinical symptoms became chronic and were resistant to conservative treatment, a resection of the coccyx was performed.

RESULTS

Histology revealed an intraosseous benign notochordal cell tumor. This tumor represents a recently described notochordal cell proliferation biologically distinct from chordomas.

CONCLUSIONS

Overdiagnosis of these notochordal cell proliferations as chordomas may occur if clinicians and pathologists are unfamiliar with the spectrum of notochordal proliferations.

Les chordomes

Chordoma is a rare bone tumor, believed to derive from notochordal rests, which generally arises at the two extremities of axial skeleton. We present a literature review on chordomas. Diagnosis has been greatly improved by MRI and immunohistochemistry. Conversely, complementary immunohistochemistry, cytometry and cytogenetic techniques have failed to improve prognosis evaluation. Radical surgery with free surgical margins is the most accurate curative treatment. Progress in radiotherapy should offer new therapeutic perspectives in the future. The recognition of new entities such as giant notochordal rest or hamartoma, and notochordal cells benign tumor, can lead to confusion since there is no consensus regarding their nature and whether or not they correspond to chordoma precursors. Prudence should be the rule in order to avoid overtreatment.

Brachyury and chordoma: the chondroid–chordoid dilemma resolved?

Chordoma, and its relationship to the notochord, has intrigued many researchers over the last two centuries. In particular, the morphological overlap with cartilaginous tumours is striking, and developmental biology has shown a tight relationship between cartilage and the notochord. This is reflected in the expression of common genes in chordoid and chondroid tumours. Wide gene expression analyses have led to the identification of key molecules that might play a crucial role in the pathogenesis of chordoma. Brachyury, a key factor in notochord fate, is significantly differentially expressed in chordoma. This not only gives insight into the histogenesis of this tumour but may also point towards new diagnostic tools in the differential diagnosis between chordoid and chondroid tumours.

Incipient chordoma: a report of two cases of early-stage chordoma arising from benign notochordal cell tumors

Chordomas are rare malignant bone tumors primarily involving both ends of the axial skeleton that present as destructive bone lesions with a large soft tissue mass. Chordomas were previously believed to arise from notochordal remnants. However, recent studies suggest the possibility that chordomas arise from benign notochordal cell tumors. We present two cases of coccygeal incipient chordoma that strengthen the new hypothesis. The first case was an 83-year-old man who died of prostatic adenocarcinoma. The second case was a 79-year-old man who died of hepatocellular carcinoma. The coccygeal tumors were composed of intraosseous and extraosseous infiltrative lesions. The intraosseous lesions consisted of both benign notochordal cell tumor and incipient chordoma. The extraosseous lesions were consistent with incipient chordoma. In addition, two other small benign notochordal cell tumors were found at a different level in case 1. It is conceivable that pre-existing intraosseous benign notochordal cell tumors transform into incipient chordoma and then extend through the cortex into the surrounding soft tissue. The incidence of incipient chordoma appears much higher than expected because chordomas are rare tumors with an incidence of one case per 1 000 000 persons per year. We suspect that unknown factors transform incipient chordoma into classic chordoma.

Adriamycin induces notochord hypertrophy with conservation of sonic hedgehog expression in abnormal ectopic notochord in the adriamycin rat model

BACKGROUND/PURPOSE

The Adriamycin rat model (ARM) is a well-established model of the Vertebral, Anorectal, Cardiac, Tracheoesophageal, Renal, Limb (VACTERL) association. The notochord, which expresses Sonic Hedgehog (Shh), has been found to be grossly malformed with ventral ectopic branches in the foregut region of embryos in the ARM. The authors designed this study to test the hypothesis that Shh-expressing ectopic notochord could contribute to an increased volume of notochord relative to total embryo volume, resulting in an increased concentration of Shh in the notochord of affected embryos.

METHODS

Adriamycin was administered intraperitoneally to rats on days 7 (E7), E8, and E9 of gestation and saline to control animals. Embryos recovered at E12 and E14 were examined immunohistochemically for Shh expression. Quantitative morphology using the Cavalieri technique was performed to determine embryo and notochord volume.

RESULTS

Embryos in both Adriamycin and control groups at E12 and E14 showed comparable levels of Shh expression in notochord at all locations. The percentage of notochord per embryo was significantly increased in Adriamycin embryos at E12 and E14 compared with equivalent controls.

CONCLUSIONS

These data suggest that Adriamycin induces notochord hypertrophy. With all regions of the notochord secreting Shh, this could result in a higher concentration gradient of Shh in close abnormal proximity to the foregut, possibly contributing to the malformations found in the VACTERL association.

Intraosseous benign notochordal cell tumours: overlooked precursors of classic chordomas?

AIMS

Intraosseous benign notochordal cell tumour is a recently recognized condition that may undergo malignant transformation to classic chordoma. The aim of this study was to describe its clinicopathological characteristics.

METHODS AND RESULTS

One hundred vertebral columns from atlas to coccyx and 61 pieces of the clival portion of the skull base, which were dissected from 100 autopsy cases, were examined microscopically. Twenty-six intraosseous benign notochordal cell tumours were found in 20 cases. The patient group consisted of 15 males and five females with a mean age of 63 years. The results, according to anatomical segments, showed that 11.5% of the clivus, 5.0% of the cervical vertebrae, 0% of the thoracic vertebrae, 2.0% of the lumbar vertebrae, and 12.0% of the sacro-coccygeal vertebrae were affected. Microscopic examination revealed well demarcated but unencapsulated sheets of bland physaliphorous cells mimicking adipocytes. The lesions lacked any intercellular myxoid matrix. The affected bone trabeculae were characteristically sclerotic.

CONCLUSIONS

The study indicated a surprisingly high incidence of intraosseous benign notochordal cell tumours. The anatomical distribution of the tumours was identical to that of classic chordomas. The results support other evidence that classic chordomas develop from intraosseous benign notochordal cell tumours.

Somites, spinal Ganglia, and centra. Enumeration and interrelationships in staged human embryos, and implications for neural tube defects

Serial sections of 99 human embryos from Carnegie stages 8-23 were investigated and 38 graphic reconstructions were evaluated. At stage 9 somite 1 is of appreciable size and is separated from the otic disc, as also in the next several stages by rhombomeres and pharyngeal arches 3 and 4, thereby differing from the chick. At stage 10 somite 1 begins to differentiate into sclerotome and dermatomyotome. At stage 11 spinal neural crest begins to develop. At stage 12 parts of somites 1-4 are being transformed into the hypoglossal cell cord. It is stressed that the numbers of somites present at stages 9-12 are part of the definition of those stages. At stage 13 dense and loose zones begin to be detectable rostrally in the sclerotomes and also, although out of phase, in the perinotochord. Spinal ganglia begin to develop in phase with the somites. At stages 14-16 the maximum number of somites observed was 38-39 rather than 42-44, as usually given. Moreover, they did not extend to the tapered end of the trunk, which is not a (vertebrated) 'tail'. At stages 17-23 the maximum number of centra was 38-39, including coccygeal vertebrae 4-5. Although most of the somites appear during primary development, all of the spinal ganglia develop during secondary development (stages 13-18). The number of ganglia was at a maximum of 35 at stage 18, but was reduced to 32 already by stage 23. Important points confirmed in this study are that the number of occipital somites in the human is four, and that the level of final closure of the caudal neuropore is future somite 31, which represents approximately future sacral vertebra 2. The interpretation of relevant neural tube defects is discussed in the light of the findings. The ascensus of the conus medullaris during the fetal period is well established, but a concomitant ascent of the situs neuroporicus is proposed here, and has implications for defects that involve tethering of the spinal cord. The main results are integrated in comprehensive graphic representations of the levels and the interrelationships of (a) somites and centra, and (b) somites, neural crest, and spinal ganglia. These may aid in the elucidation of some frequently occurring anomalous conditions.

Giant vertebral notochordal rest: a lesion distinct from chordoma: discussion of an evolving concept

A 14-year-old boy with severe back pain for several years is described. Roentgenograms, bone scans, and computed tomographic scans of the spine were normal, but magnetic resonance imaging studies showed a lumbar vertebral body lesion, confined to the bone, with low T1- and high T2-weighted signal intensities. Histologically, the lesion consisted of sheet-like notochordal-type tissue, containing physaliphorous cells but lacking the usual features of chordoma. A diagnosis of giant notochordal rest was made. A review of prior possible examples of this recently described and controversial entity is made with a discussion of its embryologic foundations and distinction from chordoma.

[Embryology and pathology of the human notochord]

The scope of this review is the report of recent findings on the developmental anatomy of the human notochord and vertebral column and the related tumors, that is chordomas. Anatomy and histology of adult intervertebral discs are also described. All the topics are completed by histochemical and immunohistochemical findings. Location and incidence of notochordal vestiges in the adult are correlated to the development of chordomas which are also described for their clinical features, skeletal distribution, spread, prognosis, and treatment. Pathology of chordomas includes morbid anatomy, histopathology, cytology, and ultrastructural findings. The seemingly distinct group of chondroid chordomas is also described. The link between chordomas and notochordal cells is stressed.

Familial chordoma, a tumor of notochordal remnants, is linked to chromosome 7q33

Chordoma is a rare tumor originating from notochordal remnants that is usually diagnosed during midlife. We performed a genomewide analysis for linkage in a family with 10 individuals affected by chordoma. The maximum two-point LOD score based on only the affected individuals was 2.21, at recombination fraction 0, at marker D7S2195 on chromosome 7q. Combined analysis of additional members of this family (11 affected individuals) and of two unrelated families (one with 2 affected individuals and the other with 3 affected individuals), with 20 markers on 7q, showed a maximum two-point LOD score of 4.05 at marker D7S500. Multipoint analysis based on only the affected individuals gave a maximum LOD score of 4.78, with an approximate 2-LOD support interval from marker D7S512 to marker D7S684. Haplotype analysis of the three families showed a minimal disease-gene region from D7S512 to D7S684, a distance of 11.1 cM and approximately 7.1 Mb. No loss of heterozygosity was found at markers D7S1804, D7S1824, and D7S2195 in four tumor samples from affected family members. These results map a locus for familial chordoma to 7q33. Further analysis of this region, to identify this gene, is ongoing.

Malformations of cranial base structures and pituitary gland in prenatal Meckel syndrome

The sella turcica region, including the clivus and the pituitary gland, was studied histologically in five human fetuses with Meckel syndrome (MS). All cases had malformed sella turcica and malformed clivus with irregularly shaped notochordal remnants. We consider that these three characteristics are constant phenotypic traits in MS. The adenohypophysis was present in three cases. In one of these, ectopia of the gland occurred with adenopituitary tissue overlying the dorsum sella, and in another remnants were found in the pharyngeal submucosa. In two fetuses the neurohypophysis was not found. The findings in the region were compared to normal findings and to findings in trisomy 18, where cranial base structures radiographically appeared similar to those in MS. We conclude that in MS specific characteristics are found in the cranial base region and that radiographic analysis needs to be supplemented by histological analysis when studying this specific region.

Vertebral intra-osseous chordoma or giant notochordal rest?

Chordomas of the lumbar vertebral bodies are rare. We report an unusual case of an entirely intraosseous chordoma of the fifth lumbar vertebra treated by vertebrectomy. Conventional radiographs and scintigraphy were normal. The lesion was well visualised by MR imaging, but showed only slight sclerosis on CT. We give our reasons for making a diagnosis of chordoma rather than giant notochordal rest and discuss the problems of management resulting from this diagnostic dilemma.

Persistence of the notochordal canal: MR and plain film appearance

We report a case of an unusually prominent persistent notochordal canal involving the T12-L5 vertebrae. This rare anatomic variation was discovered as an incidental finding in a patient with lymphoma undergoing MR imaging for evaluation of back pain. MR images showed a vertically oriented canal contiguous with the intervertebral disks traversing the anterior aspect of each affected vertebral body. Plain films showed a sclerotic rimmed central channel that flared at each vertebral endplate to merge with the disk spaces.

Apoptosis of epaxial myotome in Danforth's short-tail (Sd) mice in somites that form following notochord degeneration

Danforth's short-tail (Sd) mouse is a semidominant mutation that prevents completion of notochord development. In homozygous mutant mice, the notochord completely degenerates at embryonic day 9.5 (E9. 5), whereas the neural tube and somites continue to form, permitting analysis of somite development in the absence of inductive signals from the notochord and floor plate. In the somites formed after notochord degeneration, Myf5 expression initiates in a normal temporal sequence, but instead of the normal restriction to the dorsomedial somite, its expression extends into the ventral somite. MyoD, myogenin, and myosin heavy chain are normally expressed in the ventral myotome and there is normal development of hypaxial muscles. In contrast, subsequent to initial Myf5 expression, muscle gene expression was not detected in the dorsal myotome and a high level of apoptosis was observed with significantly decreased formation of epaxial muscles. The apoptosis of epaxial muscle in somites that formed after notochord degeneration is consistent with a role for the notochord in the survival and differentiation of the dorsal myotome.

Abnormalities of floor plate, notochord and somite differentiation in the loop-tail (Lp) mouse: a model of severe neural tube defects

Mouse embryos homozygous for the loop-tail (Lp) mutation fail to initiate neural tube closure at E8.5, leading to a severe malformation in which the neural tube remains open from midbrain to tail. During initiation of closure, the normal mouse neural plate bends sharply in the midline, at the site of the future floor plate. In contrast, Lp/Lp embryos exhibit a broad region of flat neural plate in the midline, displacing the sites of neuroepithelial bending to more lateral positions. Sonic hedgehog (Shh) and Netrin1 are expressed in abnormally broad domains in the ventral midline of the E9.5 Lp/Lp neural tube, suggesting over-abundant differentiation of the floor plate. The notochord is also abnormally broad in Lp/Lp embryos with enlarged domains of Shh and Brachyury expression. The paraxial mesoderm shows evidence of ventralisation, with increased expression of the sclerotomal marker Pax1, and diminished expression of the dermomyotomal marker Pax3. While the expression domain of Pax3 does not differ markedly from wild-type, there is a dorsal shift in the domain of Pax6 expression in the neural tube at caudal levels of Lp/Lp embryos. We suggest that the Lp mutation causes excessive differentiation of floor-plate and notochord, with over-production of Shh from these midline structures causing ventralisation of the paraxial mesoderm and, to a lesser extent, the neural tube. Comparison with other mouse mutants suggests that the enlarged floor plate may be responsible for the failure of neural tube closure in Lp/Lp embryos.

Mutations affecting the development of the embryonic zebrafish brain

In a large scale mutagenesis screen for embryonic mutants in zebrafish, we have identified 63 mutations in 24 loci affecting the morphogenesis of the zebrafish brain. The expression of marker genes and the integrity of the axonal scaffold have been studied to investigate abnormalities in regionalization, neurogenesis and axonogenesis in the brain. Mutants can be broadly classified into two groups, one affecting regionalization along the anterior-posterior or dorsal-ventral axis, and the other affecting general features of brain morphology. The first group includes one locus that is required to generate the anlage of the midbrain-hindbrain boundary region at the beginning of somitogenesis. Four loci were identified that affect dorsal-ventral patterning of the brain, including the previously described cyclops locus. Mutant embryos of this class show a reduction of ventral neuroectodermal structures and variable fusion of the eyes. The second group includes a large class of mutations affecting the formation of brain ventricles. Analysis of this class reveals the requirement of a functional cardiovascular system for ventricle enlargement during embryogenesis. Mutations in one locus lead to the formation of supernumerary primary neurons, a phenotype reminiscent of neurogenic mutants in Drosophila. Other mutant phenotypes described here range from abnormalities in the fasciculation and outgrowth of axons to defects in the diameter of the neural tube. The identified loci establish the genetic foundation for a further analysis of the development of the zebrafish embryonic brain.

Mutations affecting the formation of the notochord in the zebrafish, Danio rerio

In a large scale screen for mutants with defects in the embryonic development of the zebrafish we identified mutations in four genes, floating head (flh), momo (mom), no tail (ntl), and doc, that are required for early notochord formation. Mutations in flh and ntl have been described previously, while mom and doc are newly identified genes. Mutant mom embryos lack a notochord in the trunk, and trunk somites from the right and left side of the embryo fuse underneath the neural tube. In this respect mom appears similar to flh. In contrast, notochord precursor cells are present in both ntl and doc embryos. In order to gain a greater understanding of the phenotypes, we have analysed the expression of several axial mesoderm markers in mutant embryos of all four genes. In flh and mom, Ntl expression is normal in the germ ring and tailbud, while the expression of Ntl and other notochord markers in the axial mesodermal region is disrupted. Ntl expression is normal in doc embryos until early somitic stages, when there is a reduction in expression which is first seen in anterior regions of the embryo. This suggests a function for doc in the maintenance of ntl expression. Other notochord markers such as twist, sonic hedgehog and axial are not expressed in the axial mesoderm of ntl embryos, their expression parallels the expression of ntl in the axial mesoderm of mutant doc, flh and mom embryos, indicating that ntl is required for the expression of these markers. The role of doc in the expression of the notochord markers appears indirect via ntl. Floor plate formation is disrupted in most regions in flh and mom mutant embryos but is present in mutant ntl and doc embryos. In mutant embryos with strong ntl alleles the band of cells expressing floor plate markers is broadened. A similar broadening is also observed in the axial mesoderm underlying the floor plate of ntl embryos, suggesting a direct involvement of the notochord precursor cells in floor plate induction. Mutations in all of these four genes result in embryos lacking a horizontal myoseptum and muscle pioneer cells, both of which are thought to be induced by the notochord. These somite defects can be traced back to an impairment of the specification of the adaxial cells during early stages of development. Transplantation of wild-type cells into mutant doc embryos reveals that wild-type notochord cells are sufficient to induce horizontal myoseptum formation in the flanking mutant tissue. Thus doc, like flh and ntl, acts cell autonomously in the notochord. In addition to the four mutants with defects in early notochord formation, we have isolated 84 mutants, defining at least 15 genes, with defects in later stages of notochord development. These are listed in an appendix to this study.

Split notochord syndrome: case report

Split notochord syndrome includes a cleft of the vertebral column associated with malformation of the central nervous system. Fourteen cases involving the lumbosacral spine have been reported in the literature. We report on a female neonate who had intact function of her lower extremities, a posterior midline lumbar defect bounded by two complete spinal canals that contained two spinal cords. A meningocele, a large bowel fistula, and a mature teratoma protruded through the cleft. The baby is doing well after repair of the anomaly and placement of a ventriculoperitoneal shunt.

Development of the pharynx in normal and malformed fetuses

We studied the development of the pharynx in human embryos and fetuses. Embryos and fetuses from 4.5 mm crown-rump length (CRL) to 40 mm CRL were processed for microscopic examination. Normal fetuses from 32 mm CRL to 250 mm CRL and fetuses with malformations of the central nervous system (CNS) were cut sagittally through the midline and their pharyngeal regions were examined macroscopically. Our observations suggested that, at an early embryonic stage, the notochord and basicranium might play important roles in the formation of the human pharynx. At a later stage, the growth of the maxillomandibular portion also appears to be important in the formation of the pharynx. The finding of malformation of the pharynx in fetuses with maldevelopment of the CNS suggests that the brain may play an important role in the formation of the pharynx.

Spinal cord-notochord relationship in normal human embryos and in a human embryo with double spinal cord

Spinal cord-notochord relationship was analyzed histologically and immunohistochemically in normal human conceptuses between the 4-8 developmental weeks and in a 8-week embryo with double spinal cord. In the early 4-week embryo, the gradual closure of the neural tube along the cranio-caudal body axis was paralleled by the differentiation of the median hindge point cells at the ventral midline of the tube and by its temporary close association with the notochord. During the 5th-8th developmental weeks, the neuroepithelium differentiating into three distinct layers was accompanied by a solid, ventromedially positioned notochord. In the abnormal 8-week embryo, the additional spinal cord was located ventrolaterally from the vertebral column. Both spinal cords appeared bilaterally asymmetric, with their floor and roof plates irregularly formed. An abnormally enhanced pattern of neuroepithelial differentiation characterized their dorsal parts. Furthermore, additional spinal nerves and ganglia and an abnormal bony structure were associated with the spinal cord positioned outside the vertebral column. The underlying vertebral bodies were misshaped and contained scattered supernumerary groups of notochord cells. Our investigation underlines the importance of the notochord-neural tube relationship in the morphogenesis of the spinal cord. We suggest that the double spinal cord was induced by the split notochord.

Histological features of axial structures during embryonic and fetal stages of human craniorachischisis

Histological characteristics of developing axial structures in human conceptuses with craniorachischisis were investigated during the embryonic and fetal periods and compared with normal samples. The morphological relationship of the notochord to the axial skeleton and neural tube was analyzed along cervical and thoracic vertebral segments using serial paraffin sections. The embryonic stage of malformed conceptuses disclosed a correlated affection of the notochord and vertebral column, as well as the overlying central nervous system. The degree of histological changes within the spinal cord depended on the level of the vertebral axis examined: completely unorganized nervous tissue was overlying cervical and upper thoracic vertebrae, while more caudally it resembled a normal spinal cord. During the fetal period the histological disturbances of all axial structures were more pronounced. Extensive notochordal branching was associated with the malformed formation and ossification of the vertebral column. At this stage we found no correlation of histological changes between the spinal cord and the mesodermally derived structures (notochord, vertebral column) along the cranio-caudal body extent, as neural tissue had completely transformed into area cerebrovasculosa. We speculate that our histological observations could be the result of primary affection of mesodermal structures during very early stages of development. Divergence in histological findings within axial structures between the embryonic and fetal periods support recent mutational investigations on animals.

The carbamate insecticide ZZ-Aphox induced structural changes of gills, liver, gall-bladder, heart, and notochord of Rana perezi tadpoles

Embryos of Rana perezi were kept under laboratory conditions and treated with carbamate ZZ-Aphox at chronic doses of 0.02% and 0.14% for 9 weeks. Both the histological study and the analysis of mortality show a direct relationship between the dosage and the effects of the pesticide. The histological study of the survivors over 56 days show damages in gills, liver, gall-bladder, heart, and notochord. Damages on the epithelial of gills (on their distal portion) and gall-bladder recover over a few days, whereas those provoked on the compacting of the hepatic parenchyma and the hepatocytes, the auricle and the perintocohordal collagenic fibers alter their structure in a lasting way. Potentials of such alterations are discussed, with special reference to the possible interference of the pesticide on the successful synthesis of the supporting connective sheaths.

Developmental toxicity of caffeine in the larvae of Xenopus laevis

To examine the developmental toxicity of caffeine, Xenopus larvae just after hatching, were continuously exposed to 100-2,000 mg/L caffeine for 48 hours. Caffeine interfered with development of Xenopus larvae at a concentration of 100 mg/L and above in a concentration-dependent manner. Characteristic external abnormalities, such as shortened body with wavy fins, were observed, the severity of which was clearly concentration dependent. These larvae were frequently accompanied by abnormal body flexure and edema in the fin. Light microscopy revealed that exposure to caffeine induced severe damage in the myotome and neural tube, and at higher concentrations, the epidermal tissue was also affected. Myoblasts showed wide intercellular spaces, and their cytoplasm lost uniform staining. Ultrastructural studies of myoblasts revealed distinct myofibril disorganization and degeneration, and mitochondrial alterations. In the neural tube, cells at the dorsal part of tube showed wide intercellular spaces and some of them were segregated to the peripheral region. Furthermore, vacuole-like structures of various sizes appeared in the white matter. The outer layer of epithelial cells in the epidermis were vacuolated and swollen. With regard to the pathogenesis of myofibril damage, caffeine appeared to cause a disturbance of intracellular calcium regulation, by releasing calcium ions from the sarcoplasmic reticulum, and the mitochondrial changes observed in myotomal cells were considered to be reflective of this increased intracellular calcium ion levels. It is speculated that caffeine interferes with cell adhesion in the myotome and neural tube by affecting calcium ion regulation.