Hepatitis E virus (87A strain) propagated in A549 cells

A strain of hepatitis E virus (HEV), the 87A strain isolated in 2BS cells from the feces of a patient with hepatitis E, has been reported previously. In this study, the 87A strain was propagated in A549 cells, and the marked cytopathic effect (CPE) appeared in the infected monolayer cells. The size of this virus is about 30 nm in diameter. Furthermore, HEV-RNA from the supernatants of the virus of different passages was detected by polymerase chain reaction (PCR) amplification using ET1.1 HEV primers. A band of HEV for 239 bp from PCR products was revealed by electrophoresis. PCR products of the fourth passage were sequenced. These results show that the 87A virus replicates in the A549 cell line.

Potentiation by K+ of anoxic release of newly synthesized neuronal glutamate

Glutamate synthesis from [14C]glutamine, release of newly synthesized, labelled glutamate and cell death in primary cultures of the glutamatergic cerebellar granule cell neurones under anoxic conditions were increased by an elevation of the extracellular potassium concentration. Phenylsuccinate, an inhibitor of transmitochondrial transport and hence of glutamate synthesis from glutamine, decreased the potassium-enhanced glutamate synthesis and the release of newly synthesized glutamate and reduced cell death. Since the extracellular concentration of potassium is elevated during brain anoxia and glutamate neurotoxicity is thought to contribute to neuronal cell death under this condition, these observations may be of functional and potentially therapeutic relevance.

The extent and mechanism of the loss of function caused by strongly hypotonic solutions in rat hippocampal slices

To investigate whether prolonged severe swelling would cause irreversible injury to neurons, we exposed hippocampal tissue slices to hypotonic solutions (142 mosmol/kg) and followed the recovery of evoked responses for 5 h. Orthodromically evoked responses increased during hypotonia, except during recurrent waves of spreading depression (SD). After restoring normal osmotic pressure (pi o), evoked potentials became profoundly depressed. Following 30 min exposure, nearly maximal orthodromic responses recovered completely but responses to submaximal stimuli remained depressed, indicating elevated threshold. Following 60 min exposure, orthodromic transmission remained depressed. In slices from young animals, antidromic population spikes recovered completely, but in slices from older rats they remained partly depressed. Withdrawing calcium and raising magnesium concentration before and during hypotonic exposure resulted in modest but significant improvement of the recovery of synaptically transmitted responses, but made no difference for antidromic responses. With [Ca2+]o reduced and [Mg2+]o elevated, electrographic seizures replaced the episodes of SD during low pi o treatment. We conclude that even 60 min of severe hypotonic swelling did not kill CA1 pyramidal cells in tissue from young rats, but in its aftermath synaptic transmission was disrupted. Uptake of calcium may have played a minor role in the impairment of synaptic transmission. We propose hypothetically that post-hypotonic shrinkage of dendrites disrupted the integrity of excitatory synapses.

B cell differentiation factor-induced human B cell maturation: stimulation of intracellular calcium release

We have recently identified a novel human B cell differentiation factor, 446-BCDF, derived from anti-CD3-stimulated peripheral blood (PB) T cells. This novel cytokine, which may act through a pertussis toxin-sensitive Gi-linked receptor, induces a 5- to 100-fold increase in immunoglobulin (Ig) secretion by SAC (0.001%, v/v)-activated PB B cells. Coculture of B cells with 446-BCDF induces a decrease in intracellular cAMP which is necessary but not sufficient to drive terminal B cell differentiation. A second signal appears to be required. We therefore measured Ca2+ flux in indo-1 AM-loaded PB B cells. Stimulation with 446-BCDF resulted in an immediate rise in intracellular Ca2+ comparable to that seen with the anti-IgM mAb HB57. Ca2+ appeared to be mobilized from internal stores as pretreatment with BAPTA but not EGTA inhibited the response. Ca2+ mobilization was critical for the induction of differentiation as BAPTA pretreatment of PB B cells completely inhibited Ig secretion without affecting cell viability. In contrast, neither SAC, rIL6, IL2, IFN-gamma, nor IL4 could mobilize Ca2+. Pertussis toxin, a Gi and G0 protein inhibitor, was able to inhibit 446-BCDF-induced Ca2+ flux as well as Ig secretion. To determine whether the Ca2+ flux was generated in the course of inositol phosphate turnover, we measured IP3 turnover and the translocation of PKC from cytosol to membrane. An increase in IP3 comparable to that seen with a monoclonal anti-human IgM antibody was noted and was specifically inhibited by the 446-BCDF-specific mAb 929. Interestingly, no membrane PKC was demonstrable in either SAC- or BCDF-stimulated B cells, although PMA (50 ng/ml) could directly activate PKC. To confirm these findings functionally, B cells were stimulated with SAC and 446-BCDF in the presence of two known PKC inhibitors, staurosporin and calphostin. No inhibition of Ig secretion was detected at any concentration tested (0.39-100 nM staurosporin and 0.0625-1 microM calphostin C). These data suggest that induction of B cell differentiation is a Ca(2+)-dependent and PTX-sensitive event.

Elimination of self-peptide major histocompatibility complex class I reactivity in NOD and beta 2-microglobulin-negative mice

Nonobese diabetic (NOD) mice and beta 2-microglobulin-gene-ablated mice (beta 2M -/-) show impaired presentation of major histocompatibility complex (MHC) class I and self-peptides, structures now recognized as critical for T-cell education to endogenous peptides. The naturally occurring NOD class I presentation abnormality appears to be attributable to, in part, a quantitative defect in the production of Tap-1 mRNA; Tap-1 with Tap-2 normally functions as a transporter for stable self-peptide and class I assembly. This study attempts to reverse NOD and beta 2-M -/- mouse autoreactivity by introduced or reestablished syngeneic class I presentation. Introduction of MHC class I and self-peptides on syngeneic MHC class I-matched cells specifically prevented diabetes in NOD mice and eliminated in vitro class I-directed T-cell autoreactivity in NOD and beta 2M -/- mice. Reestablishment of endogenous class I and self-peptide presentation in NOD mice was achieved with two well-described cures for the NOD mouse, complete Freund's adjuvant and mouse hepatitis virus. Both treatments induced Tap-1 mRNA, reestablished class I presentation of endogenous antigens, and eliminated in vitro and in vivo T-cell autoreactivity of self-peptides in the class I groove. These results substantiate a therapeutic role of self-peptide complexed with class I for T-cell education and suggest that some well-described NOD treatments may work, in part, through reestablishment of tolerance through class I and self-peptide.

Poly-3-hydroxybutyrate/polyphosphate complexes form voltage-activated Ca2+ channels in the plasma membranes of Escherichia coli

The lipidic polymer, poly-3-hydroxybutyrate (PHB), is found in the plasma membranes of Escherichia col complexed to calcium polyphosphate (CaPPi). The composition, location, and putative structure of the polymer salt complexes led Reusch and Sadoff (1988) to propose that the complexes function as Ca2+ channels. Here we use bilayer patch-clamp techniques to demonstrate that voltage-activated Ca2+ channels composed of PHB and CaPPi are in the plasma membranes of E. coli. Single channel calcium currents were observed in vesicles of plasma membranes incorporated into planar bilayers of synthetic 1-palmitoyl, 2-oleoyl phosphatidylcholine. The channels were extracted from cells and incorporated into bilayers, where they displayed many of the signal characteristics of protein Ca2+ channels: voltage-activated selective for divalent over monovalent cations, permeant to Ca2+, manner by La3+, Co2+, Cd2+, and Mg2+, in that order. The channel-active extract, purified by size exclusion chromatography, was found to contain only PHB and CaPPi. This composition was confirmed by the observation of comparable single channel currents with complexes reconstituted from synthetic CaPPi and PHB, isolated from E. coli. This is the first report of a biological non-proteinaceous calcium channel. We suggest that poly-3-hydroxybutyrate/calcium polyphosphate complexes are evolutionary antecedents of protein Ca2+ channels.

Abdominal scar endometriosis: report of 28 cases

Twenty-eight cases of abdominal scar endometriosis from January, 1980 to December, 1993 are reported. Of these patients, twenty-four underwent term cesarean section, and four underwent a midtrimester abortion by abdominal hysterotomy. The majority of patients manifested symptoms 1 year after the operation. The most common was a painful mass of scar tissue that became swollen and tender during menstruation. The pathogenesis, diagnosis and treatment are discussed. In correlation with the pathological findings, the effects of drug therapy are evaluated. It was found that surgical excision is the best method of treatment.

Self-association of interleukin 2 bound to its receptor

Although radioiodinated interleukin 2 (IL-2) has been used to define the binding characteristics of the cytokine to the alpha chain of the receptor complex, we have found that unsubstituted IL-2 behaves differently. Whereas previous investigations with radioiodinated IL-2 have shown binding to the alpha chain with a Kd of 10 nM, we show that unsubstituted IL-2 binds to the alpha chain but does not reach saturation between 100 and 1000 nM. The explanation for the discrepancy between the analysis of radioiodinated and unsubstituted cytokine involves the propensity of unsubstituted IL-2 for self-association, a property that is abrogated by radioiodination. The functional relevance of our findings is indicated by the different capacities of unsubstituted and iodinated cytokine to induce prolonged proliferation of human T lymphocytes.

Noradrenaline-induced stimulation of glutamine metabolism in primary cultures of astrocytes

Effects of noradrenaline and of adrenergic subtype specific agonists on the uptake and metabolism of [14C]glutamine and [14C]glutamate in primary cultures of mouse astrocytes have been investigated. The total uptake of radioactivity from extracellular [14C]glutamine into the cells was enhanced during exposure to 100 microM noradrenaline, isoproterenol, or clonidine. This is partly due to an increased radioactivity in the glutamine pool and partly due to an increased formation of labeled glutamate from glutamine, which had become very marked (66%) after 240 min of incubation. The CO2 formation from labeled glutamine during 4 hr of incubation was enhanced about twofold in the presence of noradrenaline. Ten millimolar amino oxyacetic acid (AOAA), a transamination inhibitor, had no effect on CO2 formation from glutamine, indicating that the formation of alpha-ketoglutarate from glutamate occurs as an oxidative deamination. The stimulation of 14CO2 production from labeled glutamine was at least as large when glucose was deleted from medium, suggesting that the increased 14CO2 formation represents a stimulation of glutamine metabolism as such and is not only a reflection of an increase in oxidative metabolism of glucose and a bidirectional exchange between alpha-ketoglutarate and glutamate. The opposite process, incorporation of radioactivity from labeled glutamate into glutamine, was not enhanced in the presence of noradrenaline. The findings suggest that noradrenaline stimulates the rates of glutamine uptake, glutamate synthesis, and CO2 production from glutamine and thus increases energy supply to astrocytes but has no effect on the opposite reaction, i.e., glutamine formation from glutamate, a reaction of importance for neuronal-astrocyte interations.

Inorganic polyphosphates in the acquisition of competence in Escherichia coli

A complex of polyhydroxybutyrate (PHB), Ca2+, and inorganic polyphosphate (polyP) was proposed as the membrane component responsible for competence for DNA entry in Escherichia coli (Reusch, R. N., and Sadoff, H. L. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 4176-4180). While chemical and immunological assays and 1H NMR have unequivocally established the identity and content of PHB in the complex, comparable methods were not available for polyP. With specific enzyme assays developed for polyP, we have identified, in chloroform extracts of competent cell membranes, a novel form of polyP of about 60 to 70 residues in a stoichiometric ratio of PHB to polyP of 2:1. In E. coli mutants, incapable of synthesizing the predominant, thousand-long polyP chains, appearance of this short polyP and its inclusion in membranes can account for their capacity to develop competence and indicates an auxiliary pathway for polyP synthesis. A variety of fluorescent lipid probes demonstrate the appearance of extensive rigid domains in membranes of competent cells. We propose that the PHB.Ca2+.polyP complex perturbs the conformation of the lipid matrix, making it more permeable to charged molecules and thus allowing the entry of DNA.

[Response of ovarian endodermal sinus tumor to combination chemotherapy with cis-platinum, vincristine and bleomycin or vincristine, actinomycin and cyclophosphamide]

The treatment results of 63 cases of ovarian endodermal sinus tumor admitted to Peking Union Medical College Hospital from August 1977 through April 1992 by combination chemotherapy were reported. Patients were divided into three groups. The first group received full courses of vincristine, actinomycin and cyclophosphamide (VAC) or cis-platinum, vincristine and bleomycin (PVB) chemotherapy in adequate dosages (37 cases). The second group also received VAC or PVB chemotherapy but in inadequate dosages (17 cases). The third group took no VAC or PVB chemotherapy but some other chemotherapeutic drugs (9 cases). 28 of the 63 patients died. The 35 surviving patients have been followed for 1 to 15 years. The sustained remission rates were 81.1%, 23.5% and 11.1% for the first, second and third group respectively. As the ovarian endodermal sinus tumor is very sensitive to VAC or PVB chemotherapy an extensive or aggressive cytoreductive surgery and retroperitoneal lymphadenectomy seemed to be not necessary. Such a point of view is demonstrated by our preliminary study. The treatment results for the primary cases are significantly better than that of the recurrent cases. The sustained remission rate is 94.7% for the former while that for the latter is 66.7%.

c-fos expression as a marker of central cardiovascular neurons

Immunohistochemical detection of Fos, the protein product of the immediate-early gene c-fos, was evaluated as a functional marker of central neurons sensitive to a change of blood pressure/blood volume. Controlled hemorrhage and infusion of the hypotensive agent nitroprusside or hydralazine induced the appearance of Fos-immunoreactivity (Fos-IR) in several prominent groups of central neurons: the piriform cortex, bed nucleus of the stria terminalis, islands of Calleja, subfornical organ, central nucleus of the amygdala, parabrachial nucleus, supraoptic and paraventricular nuclei, pontine A5, locus ceruleus, ventrolateral medulla, the nucleus of the solitary tract, area postrema, and intermediolateral cell column in the spinal cord. Elevation of blood pressure by infusion of phenylephrine caused the appearance of Fos-IR in fewer groups of neurons: the bed nucleus of the stria terminalis, central nucleus of the amygdala, parabrachial nucleus, the nucleus of the solitary tract and area postrema. The differential distribution of Fos neurons in hypotensive versus hypertensive animals underscores the potential application of Fos as a metabolic marker in identifying a network of neurons responding to a specific cardiovascular challenge. Further, simultaneous characterization of the transmitter phenotype of Fos-containing neurons offers an additional advantage of this method over other conventional tract-tracing techniques.

B cell differentiation factor-induced B cell maturation: regulation via reduction in cAMP

We have previously described a novel human B cell differentiation factor (BCDF), 446-BCDF, that is distinct biochemically and functionally from other cytokines. Since signal transduction pathways involved in human B cell differentiation have been incompletely studied and are poorly understood, we assessed the effects of 446-BCDF on various intracellular second messenger systems. After exposure of B cells to 446-BCDF, intracellular cAMP concentration started to decrease at 5 min and was significantly lower at 30 min and reached the lowest level at 4 hr. In most cases, cAMP concentrations returned toward baseline by 24 hr. A cAMP analog (dibutyryl cAMP), a stimulator of adenyl cyclase (forskolin), and phosphodiesterase inhibitors (aminophylline and IBMX) which inhibited the 446-BCDF-induced decrease in intracellular cAMP, inhibited 446-BCDF-induced B cell differentiation, suggesting that the fall in intracellular cAMP was a critical event in this process. To understand the mechanism involved in the reduction of cAMP, B cells were treated with pertussis toxin (PTX), a Gi protein inhibitor. Pertussis toxin blocked 446-BCDF-induced B cell differentiation as well, suggesting that 446-BCDF may function by stimulation of a Gi-linked receptor resulting in the inhibition of adenylate cyclase with a consequent reduction in cAMP. Other cytokines known to promote Ig secretion (IL2 and IL6) also caused a reduction in cAMP, suggesting that this pathway may be generally important in B cell differentiation. Taken together, these data suggest that at least one pathway of terminal maturation in B cells may involve the reduction of intracellular cAMP.

Angiogenic potential of the avian somite

We have studied the angiogenic potential of the unsegmented paraxial mesoderm and epithelial somites of the trunk with homotopical grafts between quail and chick embryos. Quail endothelial cells of the grafts were stained with the QH-1 antibody after 1-6 days of reincubation. The unsegmented paraxial mesoderm and all parts of the epithelial somite were found to contain angioblasts which develop into QH-1 positive endothelial cells. These cells are incorporated into the lining of the host's blood vessels such as the perineural vascular plexus and the dorsal branches of the aorta. There is a certain preference as concerns the location of endothelial cells derived from different parts of the somites. Angioblasts from ventral somite halves are mainly found in ventrolateral blood vessels. Those from dorsomedial quadrants form vessels in the dermis of the back, and those from dorsolateral quadrants can be found in the ventrolateral body wall and the wing. With the exception of the dorsal perineural vascular plexus, angioblasts do not cross the median plane of the body. This shows that, although angioblasts migrate extensively, there is bilaterality of the vascular system in the trunk. It remains to be studied whether the notochord plays a role in the establishment of this bilaterality.

Morphology and morphogenesis of hepatitis E virus (strain 87A)

The morphology and morphogenesis of isolated hepatitis E virus (HEV, strain 87A) were observed by electron microscopy (EM) and immune electron microscopy (IEM). Progressively developing local vesicles, virions accumulation in crystalline arrays and viroplasmic focus were seen in cytoplasm of infected cells. Replication and assembly of the new generation viruses were closely associated with rough endoplasmic reticulum (RER), inclusion body (IB) and microfibrils. Condensation and margination of chromatin, dispersion of nucleolar material, nuclear membrane alteration and masses of threads, granular material, and fibrillar component of the nucleus were frequently found. These changes revealed that this strain virus was confirmed as a RNA virus. The shape of the virus particles appeared approximately spherical whether the specimens were from the tissue culture crude suspension or purified highly concentrated preparations. The size of the virion was about 30 nm in diameter. The viral particles appeared unsmooth and irregular in outline. The spike-like structures may be occasionally observed on the surface of some viral capsides. The diameter of the strain 87 A virus is larger than the picornavirus and smaller than the calicivirus. This strain virus is different from classical calicivirus in without the cup-shaped surface depressions. The new genus, heparnavirus genus of caliciviridae family should be proposed for HEV.

Neuroprotective effect of phenylsuccinate, an inhibitor of cytosolic glutamate formation from glutamine, under anoxic conditions but not during exposure to exogenous glutamate

Phenylsuccinate is an inhibitor of cytosolic glutamate formation from extracellular glutamine in cultured cerebellar granule cell neurons, a glutamatergic preparation. It prevents anoxic cell death in these cells as indicated by decreased lactate dehydrogenase (LDH) release and by the morphological appearance of the cells after the insult. In contrast, it does not prevent neurotoxicity by added glutamate because it is not an antagonist of the glutamate receptor.

Genetic competence in Escherichia coli requires poly-beta-hydroxybutyrate/calcium polyphosphate membrane complexes and certain divalent cations

In earlier studies of genetic competence in Escherichia coli induced with calcium-containing buffers, a strong correlation was found between transformation efficiency and the formation of poly-beta-hydroxybutyrate/calcium polyphosphate (PHB/Ca2+/PPi) complexes in the plasma membranes. In this study, we replaced Ca2+ with one of a number of other cations--monovalent, divalent, and trivalent--and found significant numbers of transformants (transformation efficiency, > 10(5)/micrograms of pBR322 DNA) only when the cells had high levels of PHB/Ca2+/PPi and the medium contained at least one of the divalent cations Ca2+, Mn2+, Sr2+, or Mg2+. Cells with high levels of the complexes were not competent when the medium did not contain these cations, but the cations were also ineffectual when the cells had few complexes. Surprisingly, Mn, Sr, and Mg were not incorporated into the complexes in place of Ca. These results indicate that PHB/Ca2+/PPi complexes and the above-mentioned divalent cations each have essential but disparate roles in genetic competence. Moreover, the strong selectivity of PHB/PPi for Ca2+ suggests the binding sites in the complexes are ionophoretic.

Infrequent co-localization of nitric oxide synthase and calcium binding proteins immunoreactivity in rat neocortical neurons

Immunoreactivity to nitric oxide synthase (NOS-IR) was detected in a small population of rat neocortical neurons scattered throughout the frontal, parietal, temporal and occipital cortices. Two-color double-labeling studies revealed that the number of NOS-IR neocortical neurons expressing immunoreactivity to the calcium binding proteins parvalbumin (PV-IR), calbindin-D28K (CB-IR) or calretinin (CR-IR), was low. The absence or low level of calcium binding proteins may imply a reduced Ca2+ buffering capacity in NOS-containing neurons, thereby contributing to their vulnerability to Ca2+ influx through the activated AMPA/kainate receptors reported by others.

Effect of anoxia on glutamate formation from glutamine in cultured neurons: dependence on neuronal subtype

Synthesis and release of glutamate formed from labeled glutamine were studied in primary cultures of the glutamatergic cerebellar granule cells and of the mainly GABAergic cerebral cortical neurons under anoxic conditions and under normoxic control conditions. Under both control and anoxic conditions cerebellar granule cells synthesized and released glutamate more intensely than cerebral cortical neurons, but this difference was enhanced under anoxic conditions. Thus, under normoxic conditions synthesis of intracellular labeled glutamate from glutamine was twice as high in cerebellar granule cell neurons as in cerebral cortical neurons during 30 min of incubation, but the release of newly synthesized labeled glutamate to the extracellular medium from cerebellar granule cell neurons was more than 4 times higher than the release from cerebral cortical neurons during 30 min of incubation. Based on these observations it is suggested that a major reason for the increase in extracellular glutamate concentration during brain ischemia may be enhanced production and release of glutamate, especially in glutamatergic neurons.

[Quantitative analysis of cellular morphometry and DNA content measurement of experimental lung adenocarcinoma]

This article reported the image analysis of normal epithelia of bronchi (group 1), hyperplasia epithelia (group 2), atypical hyperplasia epithelia (group 3) and adenocarcinoma (group 4) of the lung in the hamsters induced by tin mine dust and chimney dust in Yunnan Tin Min CO. 16 parameters were observed and compared. Each value was tested by stepwise discriminational classification and an accuracy rate of 95% was reached. DNA ploidy was investigated, and no case of > 5C cell was found in normal and hyperplasia group. Severe atypia had a lower percentage, (4.00%) and lung adenocarcinoma was characterized by a high percentage of > 5C cell (10.75%), A significant difference was shown between the percentage of > 5C cell of severe atypia and that of adenocarcinoma. Significantly different (P < 0.01).

Genes for mast-cell serine protease and their molecular evolution

Trypsin-related serine proteases are encoded by a very large gene family in mammals. We describe here a comparative analysis of the genomic DNA sequences of mouse, rat, and human mast-cell-specific serine protease genes. Strong evidence was found for multiple exchanges of genetic information between closely related members of this gene family. The 5' regulatory regions of MMCP-1 and MMCP-L share a remarkably high degree of sequence identity (98%), starting 10 base pairs downstream of exon 1 and extending to the end of the presently sequenced region at position -1347 of the MMCP-1 gene. The remaining parts of the two genes share approximately 80% sequence identity. Evidence for at least two additional, but not so recent, exchanges was found in the 3' regions of the MMCP-4 and MMCP-L genes and in the 5' regions of the genes for MMCP-1 and MMCP-2. The 5' regulatory regions of all presently characterized mouse mast-cell-specific chymotrypsin-like serine protease genes exhibit over 88% sequence identity in the region from the transcription initiation site to approximately position -600. An exception is MMCP-5 which is the most distantly related member of this subfamily. The high degree of sequence similarities indicates a strong evolutionary homogenization of the 5' regulatory region, possibly by several gene conversion events. In addition, several insertions of genetic information have been identified in genes for mast-cell chymases and genes for T-cell granzymes. A number of these have been found to represent repetitive sequences, such as L1. The previously characterized tissue-specific enhancer element of the RMCP II gene was identified as a member of a middle repetitive sequence. A cDNA for a newly discovered pseudogene, closely related to the mouse mast cell chymases was isolated by polymerase chain reaction amplification from a mouse connective tissue-like mast cell line. The structure of this cDNA is presented. We also present the characterization of a novel spliced variant of MMCP-6 that contains an alternative 3' terminal exon (exon 6). The function of this variant, if any, is still unknown. A comparative analysis of amino acid sequence identities between different hematopoietic serine proteases shows that a high degree of sequence similarity does not always correlate with relateness in cleavage specificity. This indicates that the substrate specificity evolved with a higher evolutionary rate than the degree of overall amino acid sequence identity of these proteases.

The fate of somitocoele cells in avian embryos

The early somite of avian embryos is made up of an epithelial wall and mesenchymal cells located within the somitocoele. We have studied the fate of somitocoele cells for a period of up to 6 days, using the quail-chick marker technique. We also applied the QH-1 antibody, which specifically stains hemangiopoietic cells of quail origin, and studied the proliferative activity of epithelial somites with the BrdU anti-BrdU method. Our results show that somitocoele cells mainly give rise to the ribs and peripheral parts of the intervertebral discs. After 1 and 2 days of reincubation, the grafted somitocoele cells were located in the lateral part of the sclerotome, and only a few cells migrated axially towards the notochord. In frontal sections, the cells were located in a triangular area within the cranial part of the caudal sclerotome half. After 3 days of reincubation, some of the cells had migrated cranially along the myotome. After longer reincubation periods, cells grafted into one somite could be found in two adjacent ribs. The studies with the QH-1 antibody show that a subpopulation of somitocoele cells has angiogenic potency. Endothelial cells originating from the mesenchyme of the somitocoele migrated actively and even invaded the ipsilateral half of the neural tube. In the epithelial wall of the somite, BrdU-labelled nuclei were found basally, whereas more apically the nuclei were not stained, but mitotic figures were frequently present. The somitocoele cells also showed a high proliferative activity with about 26% of nuclei labelled with BrdU.