Primary extrarenal Wilms'' tumour: identification of a putative precursor lesion

We report a case of primary extrarenal Wilms' tumour which, on histological examination, revealed a zone of hyalinized blastema adjacent to, and within the tumour capsule. The tumour showed a predominant stromal component. The presence of the hyalinized blastema adjacent to the tumour raises the possibility that some cases of extrarenal Wilms' tumour may have a precursor lesion.     

The planarian Schmidtea mediterranea as a model system for the discovery and characterization of cell‐penetrating peptides and bioportides

The general utility of the planarian Schmidtea mediterranea, an organism with remarkable regenerative capacity, was investigated as a convenient three‐dimensional model to analyse the import of cell‐penetrating peptides (CPPs) and bioportides (bioactive CPPs) into complex tissues. The unpigmented planarian blastema, 3 days post head amputation, is a robust platform to assess the penetration of red‐fluorescent CPPs into epithelial cells and deeper tissues. Three planarian proteins, Ovo, ZicA and Djeya, which collectively control head remodelling and eye regeneration following decapitation, are a convenient source of novel cationic CPP vectors. One example, Djeya1 (RKLAFRYRRIKELYNSYR), is a particularly efficient and seemingly inert CPP vector that could be further developed to assist the delivery of bioactive payloads across the plasma membrane of eukaryotic cells. Eye regeneration, following head amputation, was utilized in an effort to identify bioportides capable of influencing stem cell‐dependent morphogenesis. These investigations identified the tetradecapeptide mastoparan (INLKALAALAKKIL) as a bioportide able to influence the gross morphology of head development. We conclude that, compared with cellular monolayers, the S. mediterranea system provides many advantages and will support the identification of bioportides able to selectively modify the biology of totipotent neoblasts and, presumably, other mammalian stem cell types.     

The spectrum of persistence of testicular blastema and ectopic testicular parenchyma: a possible result of focal delay in gonadal development

Sex-cord formation and organization are important steps in testicular development and depend on adequate interactions between mesenchymal cells, pre-Sertoli cells, and germ cells. These elements form the testicular blastema, the precursor of the testicular parenchyma, morphologically characterized by poorly organized sex cords and mesenchymal components. Here, we study two uncommon testicular lesions, unrelated to other gonadal anomalies. In the first group, we describe the features of persistence of testicular blastema in three fetal autopsy cases, discussing its possible pathogenesis and clinical importance. In the second, we analyze 11 cases of ectopic testicular parenchyma in the tunica albuginea, an uncommon benign condition of uncertain clinical significance, whose main differential diagnosis is gonadal dysgenesis. Based on their similar topography within the testis, and on their possibly shared embryological origin, we propose that both lesions may represent the two extremes of a maldevelopmental spectrum resulting from a focal delay in testicular development. An erratum to this article can be found at     

Fracture Healing: A Concept of Competing Healing Factors

In the discussion concerning the theory of the healing of shaft fractures the demand for absolute stability of the fracture has been a dominating factor. This cannot be an absolute prerequisite because fractures of the tibia or femur heal well even with continued weight-bearing and movement. the ingrowth of vessels is apparently not a crucial factor. It is evident, however, that fractures caused by direct violence with soft tissue damage heal more slowly than fractures caused by indirect violence, irrespective of the treatment. Soft tissue heals with fibrous scar; fractures heal by bone regeneration. the author postulates that the damaged tissue stimulates (possibly via molecular determinants) the structural genes of undifferentiated cells to produce mRNA and proteins for either fibrous tissue or bone formation. the rate of healing of the fracture is determined by the degree of bone damage in relation to soft tissue damage. in fractures with extensive soft tissue injury there occurs a competitive condition in the common haematoma, with a risk of delayed fracture healing due to the dominance of cells that are triggered off by fibrous tissue formation.     

A comparative study of gland cells implicated in the nerve dependence of salamander limb regeneration

Limb regeneration in salamanders proceeds by formation of the blastema, a mound of proliferating mesenchymal cells surrounded by a wound epithelium. Regeneration by the blastema depends on the presence of regenerating nerves and in earlier work it was shown that axons upregulate the expression of newt anterior gradient (nAG) protein first in Schwann cells of the nerve sheath and second in dermal glands underlying the wound epidermis. The expression of nAG protein after plasmid electroporation was shown to rescue a denervated newt blastema and allow regeneration to the digit stage. We have examined the dermal glands by scanning and transmission electron microscopy combined with immunogold labelling of the nAG protein. It is expressed in secretory granules of ductless glands, which apparently discharge by a holocrine mechanism. No external ducts were observed in the wound epithelium of the newt and axolotl. The larval skin of the axolotl has dermal glands but these are absent under the wound epithelium. The nerve sheath was stained post-amputation in innervated but not denervated blastemas with an antibody to axolotl anterior gradient protein. This antibody reacted with axolotl Leydig cells in the wound epithelium and normal epidermis. Staining was markedly decreased in the wound epithelium after denervation but not in the epidermis. Therefore, in both newt and axolotl the regenerating axons induce nAG protein in the nerve sheath and subsequently the protein is expressed by gland cells, under (newt) or within (axolotl) the wound epithelium, which discharge by a holocrine mechanism. These findings serve to unify the nerve dependence of limb regeneration.     

Characterization of a Monoclonal Antibody Recognizing the Blastemal Element of Wilms' Tumors and Fetal Kidneys

A blastema-associated antigen (BLA.-1) was detected using a monoclonal antibody against malignant blastema from a Wilms' tumor. The localization of BLA-I was investigated in a series of nine Wilms' cases, five fetal, one childhood, and two adult kidneys. In this series, BLA-1 antibody consistently stained cell surfaces of all Wilms' tumors containing blastemal components. The same staining pattern was maintained in tumors grown as heterotransplants in nude mice. The expression of BLA-1 antigen was examined in normal blastema of fetal kidneys. BLA-1 was immunolocalized to condensed blastemal cells in the nephrogenic zone throughout gestation. In addition, kidney samples from a young child or adults contained no blastemal cells and therefore showed no blastemal cell surface staining. Glomerular mesangial cell staining was demonstrated in kidneys from 12 weeks of gestation through adulthood. This staining in developing and mature glomeruli implies that mesangial cells may be derived from condensed blastemal cells. The finding of a cell surface antigen common to Wilms' blastema, fetal blastema, and mesangial cells has not been previously demonstrated.     

A variant of the Wiedemann-Beckwith syndrome

The following combination of findings were established by histological examination of biopsy or autopsy material in an 11-day-old male baby: congenital mesoblastic nephroma, nodular renal blastema, dysgenetic pancreatic cyst, cytomegaly of the adrenal cortex, hyperplasia and hypertrophy of the islets of Langerhans, hypoplasia of the thymus and the lymphatic tissue. Since some of these changes constitute the characteristic histological findings in the Wiedemann-Beckwith syndrome and the remainder can be readily reconciled with it, the assignment of this case to this syndrome is discussed. Although the three cardinal symptoms are lacking, the combination of findings are interpreted as a variant of the Wiedemann-Beck with syndrome.     

Inguinal nephroblastoma

Summary A case of an extrarenal nephroblastoma is reported which was located in the inguinal region. In the surrounding fat tissue normal ectopic glomerular and tubular structures and two more nephroblastomas were found. Therefore and because of negative clinical investigations in regarding of a renal malignant tumour the inguinal mass was thought to be the primary tumour and not a metastasis. This conclusion is important for the diagnosis and therapy.Chirurgische Abteilung des Städtischen Krankenhaus Kemperhof, D-5400 Koblenz, Federal Republic of Germany