An experimental study on the relative distribution of the somitic and somatic plate mesoderm to the abdominal wall of avian embryos

Summary The origin of the structures of the abdominal wall in avian embryos was studied by using the quail-chick marker system. It was concluded that the muscles originate from somitic cells while tendons, fasciae and the intramuscular fibroblasts, as also the remaining connective tissue, derive from the somatic plate mesoderm.Supported by the Deutsche Forschungsgemeinschaft (CH 44/2).     

Effects of 5-bromodeoxyuridine on in vitro development of mouse embryos in the early somitic stage

Summary The inhibitory effect of 5-bromodeoxyuridine on the early somitic stages of mouse embryos was largely prevented in the presence of excess thymidine but only partially prevented by deoxycytidine.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Upon amputation of the urodele limb, the epidermal cells surrounding the amputation plane migrate to heal the wound. The resulting wound epidermis (WE) induces the regeneration process, resulting in blastema formation, cell division, and ultimately repatterning into a new limb. Despite its central role in the initiation of limb regeneration, little is known about how the WE forms. Here we discuss various models of WE formation and the experimental data in support of each.     

Ultrastructural changes in the dorsal root ganglia evoked by thalidomide in rabbits.

Administration of the teratogenic drug thalidomide to pregnant does produces ultrastructural changes in foetal ganglion cells, Schwann cells and axons in the posterior root ganglia corresponding to forelimb segments deformed by the orug. Ultrastructural changes in ganglia appear on the 13th day of gestation, i.e., preceding the appearance of limb malformation.     

Effect of amputation and limb regeneration on the pars distalis of the newt,Notophthalmus viridescens

Summary A study of the pituitary of the newt,Notophthalmus viridescens, during limb regeneration indicated no observable changes in histology or ultrastructure of any of the cells of the pars distalis when compared with the pars distalis of unamputated control newts.This investigation supported by a grant from the National Research Council of Canada to S.R. Scadding.     

Direct demonstration of production of transforming growth factor activity by embryonic chick tissue

The presence of transforming growth factor activity in early chick embryos was directly demonstrated by the ability of limb and tail buds to induce anchorage independent division in NRK 49 f cells. Colony number increased with limb bud number and developmental stage. Medium conditioned by tail buds contained some stimulating effect, and strongly promoted the action of other transforming growth factors.     

Direct demonstration of production of transforming growth factor activity by embryonic chick tissue

Summary The presence of transforming growth factor activity in early chick embryos was directly demonstrated by the ability of limb and tail buds to induce anchorage independent division in NRK 49f cells. Colony number increased with limb bud number and developmental stage. Medium conditioned by tail buds contained some stimulating effect, and strongly promoted the action of other transforming growth factors.     

Teratogenicity screening in standardized chick embryo culture: effects of dexamethasone and diphenylhydantoin

Teratogenic and toxic effects of DXM and DPH were tested using a standardized chick embryo culture. Survival, growth and malformations were scored with respect to the drug concentrations used. DXM (greater than 10(-8) mol/l) inhibited the differentiation of the extraembryonic blood circulation and induced craniofacial anomalies. DPH (greater than 1.5 10(-5) mol/l) induced cardiomegaly, craniofacial and somitic anomalies. Both drugs were lethal at 10(-3) mol/l. Comparison of results obtained with 8 drugs shows that the method has a good discriminative power and specificity and that it can be used as a simple, reliable and economical primary screening test, making it possible to reduce the use of animals in toxicological studies.     

Effect of testosterone and 17-beta estradiol on limb regeneration in the newt, Notophthalmus viridescens

Gonadectomy, or injections of testosterone or 17-beta estradiol, had no apparent effect on the rate of regeneration or histological appearance of limb regenerates in the newt, Notophthalmus viridescens. Neither promotion, nor inhibition of limb regeneration was observed.     

Ultrastructural changes in the dorsal root ganglia evoked by thalidomide in rabbits

Summary Administration of the teratogenic drug thalidomide to pregnant does produces ultrastructural changes in foetal ganglion cells, Schwann cells and axons in the posterior root ganglia corresponding to forelimb segments deformed by the drug. Ultrasttructural changes in ganglia appear on the 13th day of gestation, i.e., preceding the appearance of limb malformation.This work was supported by a grant from Foundation 41.We are grateful to MissC. Ellis and Mr.P. Westphal for technical assistance.     

DPH-induced macrocytosis in the 14-day rat foetus

Summary Phenytoin injected in the pregnant rat induces in the 14-day-old foetus macrocytosis of the primitive red blood cells which is sometimes linked with limb haemorrhages. The action of the drug is possibly the result of a blood circulation disturbance.     

DPH-induced macrocytosis in the 14-day rat foetus

Phenytoin injected in the pregnant rat induces in the 14-day-old foetus macrocytosis of the primitive red blood cells which is sometimes linked with limb haemorrhages. The action of the drug is possibly the result of a blood circulation disturbance.     

Molecular and Cellular Basis of Regeneration and Tissue Repair

The Xenopus tadpole is a favourable organism for regeneration research because it is suitable for a wide range of micromanipulative procedures and for a wide range of transgenic methods. Combination of these techniques enables genes to be activated or inhibited at specific times and in specific tissue types to a much higher degree than in any other organism capable of regeneration. Regenerating systems include the tail, the limb buds and the lens. The study of tail regeneration has shown that each tissue type supplies the cells for its own replacement: there is no detectable de-differentiation or metaplasia. Signalling systems needed for regeneration include the BMP and Notch signalling pathways, and perhaps also the Wnt and FGF pathways. The limb buds will regenerate completely at early stages, but not once they are fully differentiated. This provides a good opportunity to study the loss of regenerative ability using transgenic methods.     

Small lymphocyte production and lymphoid cell proliferation in mouse bone marrow

In mice given 3H-thymidine systemically during temporary circulatory occlusion of one hind limb, comparison of the labeling of rapidly-renewing small lymphocytes in the tibial marrows demonstrated that these cells were locally produced. Labeling by 3H-thymidine infusion revealed that many marrow large lymphoid cells, presumptive small lymphocyte progenitors, had a marked proliferative activity and rapid turnover which varied according to cell size, was maximal in young mice and declined with increasing age.     

Cell culture models and animal models for studying the patho-physiological role of renal aquaporins

Aquaporins (AQPs) are key players regulating urinary-concentrating ability. To date, eight aquaporins have been characterized and localized along the nephron, namely, AQP1 located in the proximal tubule, thin descending limb of Henle, and vasa recta; AQP2, AQP3 and AQP4 in collecting duct principal cells; AQP5 in intercalated cell type B; AQP6 in intercalated cells type A in the papilla; AQP7, AQP8 and AQP11 in the proximal tubule. AQP2, whose expression and cellular distribution is dependent on vasopressin stimulation, is involved in hereditary and acquired diseases affecting urine-concentrating mechanisms. Due to the lack of selective aquaporin inhibitors, the patho-physiological role of renal aquaporins has not yet been completely clarified, and despite extensive studies, several questions remain unanswered. Until the recent and large-scale development of genetic manipulation technology, which has led to the generation of transgenic mice models, our knowledge on renal aquaporin regulation was mainly based on in vitro studies with suitable renal cell models. Transgenic and knockout technology approaches are providing pivotal information on the role of aquaporins in health and disease. The main goal of this review is to update and summarize what we can learn from cell and animal models that will shed more light on our understanding of aquaporin-dependent renal water regulation.     

Localization of brain type creatine kinase in kidney epithelial cell subpopulations in rat

Summary Immunoperoxidase studies of rat kidney using antibody to brain type isoenzyme of creatine kinase (BB) revealed a specific staining in the epithelial cells of the thick ascending limb of the Henle's loop and collecting tubule. Occasional epithelial cells in cortical tubules that lack brush border were also positive for BB. Renal glomeruli and proximal tubules showed no immunoreactivity to this enzyme.     

Localization of brain type creatine kinase in kidney epithelial cell subpopulations in rat

Immunoperoxidase studies of rat kidney using antibody to brain type isoenzyme of creatine kinase (BB) revealed a specific staining in the epithelial cells of the thick ascending limb of the Henle's loop and collecting tubule. Occasional epithelial cells in cortical tubules that lack brush border were also positive for BB. Renal glomeruli and proximal tubules showed no immunoreactivity to this enzyme.     

Teratogenicity screening in standardized chick embryo culture: Effects of dexamethasone and diphenylhydantoin

Summary Teratogenic and toxic effects of DXM and DPH were tested using a standardized chick embryo culture. Survival, growth and malformations were scored with respect to the drug concentrations used. DXM (>10^–8 mol/l) inhibited the differentiation of the extraembryonic blood circulation and induced craniofacial anomalies. DPH (>1.5 10^–5 mol/l) induced cardiomegaly, craniofacial and somitic anomalies. Both drugs were lethal at 10^–3 mol/l. Comparison of results obtained with 8 drugs shows that the method has a good discriminative power and specificity and that it can be used as a simple, reliable and economical primary screening test, making it possible to reduce the use of animals in toxicological studies.Supported by the grant 4.790.0.84.17 from the Swiss National Science Foundation.     

General effects of cytosine arabinoside on the embryo of reptiles

Administered to eggs of Reptilia (Lacerta viridis and Anguis fragilis), cytosine-arabinoside induced numerous embryonic malformations, among which microphthalmia and limb deformities. On the other hand this drug delayed the retrogression of the apical ridge of the limb buds in Anguis fragilis.     

Effects of ablation of the hindlimb on the organization of the ventral horn of the spinal cord in the lumbar region of green lizard embryos (Lacerta viridis Laur.)]

After extirpation of an hind limb in embryos of Lacerta viridis, numerous motor neuroblasts degenerate on the operated side, in the ventral horn of the lumbar spinal cord and the corresponding motor column is reduced or disappears. The lumbar spinal ganglia are affected and reduced on the operated side.