Demonstration of cytoplasmic processes in Millipore filters permitting kidney tubule induction

Development ◽  
1975 ◽  
Vol 33 (1) ◽  
pp. 187-203
Author(s):  
E. Lehtonen ◽  
J. Wartiovaara ◽  
S. Nordling ◽  
L. Saxén
Keyword(s):  
Spinal Cord ◽  
Kidney Tubules ◽  
Metanephric Mesenchyme ◽  
Kidney Tubule ◽  
Close Apposition ◽  
Cytoplasmic Material ◽  
Diffusion Studies ◽  
Induction System ◽  
Cytoplasmic Processes ◽  
Millipore Filters

The presence of cytoplasmic material inside thin Millipore filters between interacting mouse metanephric mesenchyme and spinal cord was investigated using different fixation methods. The transmission of induction was studied from sections of Zenker-fixed paraffin-embedded explants. Formation of kidney tubules was taken as evidence for induction. Filters with 0·8 and 0·22 μm pores permitted induction, whereas only 6 out of 31 filters with 0·1 μm. pores did so. Glutaraldehyde-fixed Epon-embedded explants were used for study of cytoplasmic penetration into filters. In thick sections, filters with large pores were seen to contain cytoplasmic material at all levels. Filters with 0·1 μm pores usually showed only shallow ingrowth, but those which had permitted passage of induction contained material at least half way from the spinal cord and shallow ingrowth from the mesenchyme. With 0·8 μm filters the ingrowths from both sides met first after 18 h of transfilter cultivation. This has previously been shown to be the minimum time needed for induction to take place in this system. In electron microscopy cytoplasmic processes were seen deep inside the 0·8 and 0·22 μm filters regularly permitting induction. In small pores such material was only preserved by certain glutaraldehyde fixatives. Diffusion studies did not reveal major differences between induction-permitting 0·22 μm filters and induction-preventing 0·1 μm filters. Thus in the kidney tubule induction system this and our previous work speak in favour of a mechanism based on close apposition of cells rather than on long-range diffusion of inductive substances or on matrix interaction.

Transfilter induction of kidney tubules as a function of the extent and duration of intercellular contacts

Development ◽  
1978 ◽  
Vol 47 (1) ◽  
pp. 97-109
Author(s):  
Lauri Saxén ◽  
Eero Lehtonen
Keyword(s):  
Pore Size ◽  
Filter Material ◽  
Culture Conditions ◽  
Kidney Tubules ◽  
Pore Density ◽  
Kidney Tubule ◽  
Intercellular Contacts ◽  
Cytoplasmic Processes ◽  
Kinetics Of

The kinetics of kidney tubule induction were examined in transfilter experiments by varying the time of transfilter apposition, the porosity and pore size of the filters, and the culture conditions. Transfilter contact between the interacting cells is established within an hour when cytoplasmic processes emerge through the interposed filter; then a further 16–24 h are needed for completion of induction. This lag is a function of thickness and pore size of the filter, and is not reduced by precultivation of the inductor on the filter. Material that accumulates on the far side of the filter during such cultivation displays no morphogenetic activity. The intensity of the mesenchymal response was roughly quantified and shown to be a function of pore size, pore density and duration of transfilter contact.

scholarly journals Apoptosis in metanephric development.

1992 ◽  
Vol 119 (5) ◽  
pp. 1327-1333 ◽  
Author(s):  
C Koseki ◽  
D Herzlinger ◽  
Q al-Awqati
Keyword(s):  
Spinal Cord ◽  
Protein Kinase ◽  
Transcriptional Activation ◽  
Phorbol Esters ◽  
Dna Degradation ◽  
Morphological Evidence ◽  
Metanephric Mesenchyme ◽  
Embryonic Spinal Cord

During metanephric development, non-polarized mesenchymal cells are induced to form the epithelial structures of the nephron following interaction with extracellular matrix proteins and factors produced by the inducing tissue, ureteric bud. This induction can occur in a transfilter organ culture system where it can also be produced by heterologous cells such as the embryonic spinal cord. We found that when embryonic mesenchyme was induced in vitro and in vivo, many of the cells surrounding the new epithelium showed morphological evidence of programmed cell death (apoptosis) such as condensed nuclei, fragmented cytoplasm, and cell shrinking. A biochemical correlate of apoptosis is the transcriptional activation of a calcium-sensitive endonuclease. Indeed, DNA isolated from uninduced mesenchyme showed progressive degradation, a process that was prevented by treatment with actinomycin-D or cycloheximide and by buffering intracellular calcium. These results demonstrate that the metanephric mesenchyme is programmed for apoptosis. Incubation of mesenchyme with a heterologous inducer, embryonic spinal cord prevented this DNA degradation. To investigate the mechanism by which inducers prevented apoptosis we tested the effects of protein kinase C modulators on this process. Phorbol esters mimicked the effects of the inducer and staurosporine, an inhibitor of this protein kinase, prevented the effect of the inducer. EGF also prevented DNA degradation but did not lead to differentiation. These results demonstrate that conversion of mesenchyme to epithelial requires at least two steps, rescue of the mesenchyme from apoptosis and induction of differentiation.

scholarly journals Cytologic and histologic features of spinal cord ependymoma in a young dog: a case report

2010 ◽  
Vol 55 (No. 1) ◽  
pp. 35-38 ◽  
Author(s):  
A. Sfacteria ◽  
F. Macrì ◽  
L. Perillo ◽  
G. Rapisarda ◽  
G. Lanteri ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Case Report ◽  
Contrast Medium ◽  
Histological Examination ◽  
Neoplastic Cells ◽  
Spinal Ependymoma ◽  
Eosinophilic Cytoplasm ◽  
Cytoplasmic Processes ◽  
Positive Results ◽  
Fibrillar Network

A case of intramedullary ependymoma in a young dog is reported. A two year old dog was presented with paralysis of the forelimbs. At myelographic examination, an intramedullary pattern, blocking the progression of contrast medium, was observed. At necropsy, a 3 × 2 cm white-greyish mass was found extending from the 3<sup>rd</sup> to 5<sup>th</sup> lumbar levels. At cytological and histological examination, the mass was highly cellular and was comprised of ovoid cells with indistinct borders, elongated eosinophilic cytoplasm and round to oval vesicular nuclei. Cytoplasmic processes formed a fibrillar network wherein true rosettes and many pseudorosettes around a fibrovascular stroma were observed. Immunohistochemistry for vimentin and GFAP gave strong positive results in the neoplastic cells, especially around pseudorosettes and confirmed the diagnosis of intramedullary spinal ependymoma.

Epithelio-mesenchymal interface during mouse kidney tubule induction in vivo

Development ◽  
1975 ◽  
Vol 34 (3) ◽  
pp. 695-705
Author(s):  
E. Lehtonen
Keyword(s):  
Mesenchymal Cell ◽  
Ruthenium Red ◽  
Mouse Kidney ◽  
Embryonic Induction ◽  
Metanephric Mesenchyme ◽  
Kidney Tubule ◽  
Extracellular Material ◽  
20 Nm ◽  
Scanning Electron

Transmission and scanning electron microscopy were used to study the epithelio-mesenchymal interface between the interacting mouse ureter-bud and the metanephric mesenchyme. The gap between the epithelial and mesenchymal cells varied in width. At the stalk of the ureter-bud the interspace was often about 1 µm, but in the inductively active areas at the tips of the branching ureter-bud epithelio-mesenchymal contacts were seen through discontinuities in the basal lamina. At these points the gap between the interacting cells was often less than 20 nm, in places less than 10 nm. The amount of electron-dense, ruthenium-red-positive material was greatest at the stalk of the ureter-bud, but only a small amount of extracellular material was found between the interacting cells at the tips. Whether epithelio-mesenchymal cell contacts play a role in kidney tubule induction is not yet known, but their existence in the inductively active areas and their absence in inactive zones suggests that they are morphogenetically significant. The finding also obviates the need to postulate long-range transmission of inductive signals to explain this example of embryonic induction.

scholarly journals Quantitative Proteomics of All 14 Renal Tubule Segments in Rat

2020 ◽  
Vol 31 (6) ◽  
pp. 1255-1266 ◽  
Author(s):  
Kavee Limbutara ◽  
Chung-Lin Chou ◽  
Mark A. Knepper
Keyword(s):  
Protein Function ◽  
Renal Tubule ◽  
Rat Kidney ◽  
Single Cells ◽  
Specific Protein ◽  
Online Information ◽  
Kidney Tubules ◽  
Kidney Tubule ◽  
Link Protein ◽  
Expression Atlas

BackgroundPrevious research has used RNA sequencing in microdissected kidney tubules or single cells isolated from the kidney to profile gene expression in each type of kidney tubule epithelial cell. However, because proteins, not mRNA molecules, mediate most cellular functions, it is desirable to know the identity and amounts of each protein species to understand function. Recent improvements in the sensitivity of mass spectrometers offered us the ability to quantify the proteins expressed in each of 14 different renal tubule segments from rat.MethodsWe manually dissected kidney tubules from rat kidneys and subjected samples to protein mass spectrometry. We used the “proteomic ruler” technique to estimate the number of molecules of each protein per cell.ResultsOver the 44 samples analyzed, the average number of quantified proteins per segment was 4234, accounting for at least 99% of protein molecules in each cell. We have made the data publicly available online at the Kidney Tubule Expression Atlas website (https://esbl.nhlbi.nih.gov/KTEA/). Protein abundance along the renal tubule for many commonly studied water and solute transport proteins and metabolic enzymes matched expectations from prior localization studies, demonstrating the overall reliability of the data. The site features a “correlated protein” function, which we used to identify cell type–specific transcription factors expressed along the renal tubule.ConclusionsWe identified and quantified proteins expressed in each of the 14 segments of rat kidney tubules and used the proteomic data that we obtained to create an online information resource, the Kidney Tubule Expression Atlas. This resource will allow users throughout the world to browse segment-specific protein expression data and download them for their own research.

scholarly journals Recognition of the laminin E8 cell-binding site by an integrin possessing the alpha 6 subunit is essential for epithelial polarization in developing kidney tubules.

1990 ◽  
Vol 111 (3) ◽  
pp. 1265-1273 ◽  
Author(s):  
L Sorokin ◽  
A Sonnenberg ◽  
M Aumailley ◽  
R Timpl ◽  
P Ekblom
Keyword(s):  
Epithelial Cells ◽  
Binding Site ◽  
Apical Cell ◽  
Cell Types ◽  
Metanephric Mesenchyme ◽  
Kidney Tubule ◽  
Cell Binding ◽  
Developing Kidney ◽  
A Chain ◽  
Integrin Alpha 6

It has been previously shown that A-chain and domain(E8)-specific antibodies to laminin that inhibit cell adhesion also interfere with the establishment of epithelial cell polarity during kidney tubule development (Klein, G., M. Langegger, R. Timpl, and P. Ekblom. 1988. Cell. 55:331-341). A monoclonal antibody specific for the integrin alpha 6 subunit, which selectively blocks cell binding to E8, was used to study the receptors involved. Immunofluorescence staining of embryonic kidneys and of organ cultures of metanephric mesenchyme demonstrated coappearance of the integrin alpha 6 subunit and the laminin A-chain in regions where nonpolarized mesenchymal cells convert into polarized epithelial cells. Both epitopes showed marked colocalization in basal areas of tubules, while an exclusive immunostaining for alpha 6 was observed in lateral and apical cell surfaces of the tubular epithelial cells. Organ culture studies demonstrated a consistent inhibition of kidney epithelium development by antibodies against the alpha 6 subunit. The data suggest that the recognition of E8 cell-binding site of laminin by a specific integrin is crucial for the formation of kidney tubule epithelium from undifferentiated mesenchymal stem cells. In some other cell types (endothelium, some ureter cells) an exclusive expression of alpha 6 with no apparent colocalization of laminin A-chain in the corresponding basement membrane was seen. Thus, in these cells, integrins possessing the alpha 6 subunit may bind to laminin isoforms that differ from those synthesized by developing tubules.

Effects of kidney tubule obstruction on glomerular function in rats

1979 ◽  
Vol 237 (5) ◽  
pp. F379-F385 ◽  
Author(s):  
G. A. Tanner
Keyword(s):  
Blood Flow ◽  
Capillary Pressure ◽  
Renal Blood Flow ◽  
Ureteral Obstruction ◽  
Castor Oil ◽  
Kidney Tubules ◽  
Kidney Tubule ◽  
Glomerular Function ◽  
Local Mechanism ◽  
Single Kidney

The effects of chronic blockade of single kidney tubules on glomerular capillary pressure (GCP) and blood flow were examined in anesthetized rats. Tubule blockade with castor oil for 24 h decreased GCP from 48.0 +/- 3.8 to 39.5 +/- 4.7 mmHg (P less than 0.001). The full decrease in GCP observed at 24 h was apparent by about 12 h. Bilateral ureteral obstruction for 24 h prevented a decrease in GCP. Nonradioactive microspheres (8.4 +/- 0.84 micron diam) were used to assess relative blood flow to blocked and normal nephrons. These microspheres were completely extracted by rat kidneys and had no effect on total renal blood flow. The ratio of microsphere counts in glomeruli of blocked versus normal nephrons averaged 0.61 +/- 0.21, indicating a significantly (P less than 0.001) decreased glomerular blood flow in nephrons obstructed for 24 h. Since both GCP and blood flow were reduced after tubule obstruction, afferent arteriolar constriction is involved. The data suggest a local mechanism activated by prolonged tubule blockade which shifts filtrate formation and blood flow away from blocked nephrons.

Wnt-4 is a mesenchymal signal for epithelial transformation of metanephric mesenchyme in the developing kidney

Development ◽  
1998 ◽  
Vol 125 (21) ◽  
pp. 4225-4234 ◽  
Author(s):  
A. Kispert ◽  
S. Vainio ◽  
A.P. McMahon
Keyword(s):  
Spinal Cord ◽  
Cell Contact ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Tubule Formation ◽  
Dorsal Spinal Cord ◽  
Molecular Events ◽  
Developing Kidney ◽  
Sulphated Glycosaminoglycans ◽  
Additional Support

Development of the mammalian kidney is initiated by ingrowth of the ureteric bud into the metanephric blastema. In response to signal(s) from the ureter, mesenchymal cells condense, aggregate into pretubular clusters, and undergo epithelialisation to form simple epithelial tubules. Subsequent morphogenesis and differentiation of the tubular epithelium lead to the establishment of a functional nephron. Here we demonstrate that Wnt-4, a secreted glycoprotein which is required for tubule formation, is sufficient to trigger tubulogenesis in isolated metanephric mesenchyme, whereas Wnt-11 which is expressed in the tip of the growing ureter is not. Wnt-4 signaling depends on cell contact and sulphated glycosaminoglycans and is only required for triggering tubulogenesis but not for later events. The Wnt-4 signal can be replaced by other members of the Wnt gene family including Wnt-1, Wnt-3a, Wnt-7a and Wnt-7b. Further, dorsal spinal cord, which has been thought to mimic ureteric signaling in tubule induction induces Wnt-4 mutant as well as wild-type mesenchyme suggesting that spinal cord derived signal(s) most likely act by mimicking the normal mesenchymal action of Wnt-4. These results lend additional support to the notion that Wnt-4 is a key auto-regulator of the mesenchymal to epithelial transformation that underpins nephrogenesis adding another level of complexity in the hierarchy of molecular events mediating tubulogenesis.

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