Cancer and Vascular Differentiation

Author(s):  
Roni Aloni
1975 ◽  
Vol 23 (5) ◽  
pp. 745 ◽  
Author(s):  
RF Williams ◽  
RHM Langer

From an analysis of the length-time relation for tiller growth in wheat it was concluded that tillers which emerged traced a discontinuous curve, and that the discontinuity marked a critical event in tiller growth. Tiller buds which did not emerge as tillers continued to grow even more slowly, at least until anthesis of the primary shoot. The critical event was identified as that of escape from the cavity in which the bud was tightly contained throughout early development. The timing of vascular differentiation in tiller buds was shown to be size-dependent and there was no evidence for any correlation with the critical event of escape. A strong negative correlation between the lengths of the 3rd tiller buds and their subtending internodes was established, and the presence or absence of the 4th tiller bud was also correlated with its internode length. Current hypotheses relating to apical dominance are reviewed, and it is suggested that the dynamic physical constraints implicit in tiller bud growth add a further complication. It was concluded that hormonal, nutritional and constraint mechanisms need to be integrated as partial mechanisms which interacted at the interfaces between successive levels within apical systems.


1980 ◽  
Vol 58 (12) ◽  
pp. 1351-1369 ◽  
Author(s):  
W. A. Charlton

There are several files of metaxylem cells in root apices of Pontederia cordata L., each considered to consist of a series of prospective vessels with their ends in contact. Two longitudinally adjacent vessels may be in the same file of cells produced by the root apex or in adjacent files. As the root grows, successive prospective vessels are added to the apical ends of most of the files but not all files are continued. Addition of prospective vessels appears to take place within the "quiescent centre" of the root apical meristem. Where files are not continued there is no immediate readjustment of remaining files. The longitudinal and transverse distribution of components of the vascular system (including protophloem and protoxylem) is discussed in relation to the means by which the pattern of development may be controlled. Rates of production of vessels and the final lengths of the vessels are estimated. The observations and deductions are discussed in relation to other studies of root growth, vascular differentiation, and vascular pattern formation and maintenance.


Neurosurgery ◽  
1986 ◽  
Vol 19 (3) ◽  
pp. 426-433 ◽  
Author(s):  
David S. Moss ◽  
Stephen J. Haines ◽  
Arnold S. Leonard ◽  
Louis P. Dehner

Abstract Congenital neoplasms of the central nervous system are extremely rare, although they have been well documented since the earliest reports from the mid-19th century. Medulloblastoma, other primitive neuroectodermal tumors, and various types of gliomas have comprised the majority of cases. This report describes a highly unusual infratentorial and supratentorial tumor presenting as a scalp mass in a neonate who experienced in utero distress. The supratentorial mass extended through a defect in the skull to the parietooccipital lobe, and the infratentorial aspect involved the 9th and 10th cranial nerves in the region of the cerebellopontine angle. A complex spindle cell neoplasm incorporating peripheral nerve sheath and vascular characteristics was further characterized by electron microscopy and immunohistochemistry. Based upon these studies, the tumor was interpreted as a congenital schwannoma with divergent vascular differentiation. The child has been tumor-free for approximately 2 years after the initial operative procedure.


Blood ◽  
2004 ◽  
Vol 103 (1) ◽  
pp. 100-109 ◽  
Author(s):  
Zhengyu Wang ◽  
Kenneth Cohen ◽  
Ying Shao ◽  
Pamela Mole ◽  
David Dombkowski ◽  
...  

Abstract Differentiation of pluripotent embryonic stem (ES) cells is associated with expression of fate-specifying gene products. Coordinated development, however, must involve modifying factors that enable differentiation and growth to adjust in response to local microenvironmental determinants. We report here that the ephrin receptor, EphB4, known to be spatially restricted in expression and critical for organized vessel formation, modifies the rate and magnitude of ES cells acquiring genotypic and phenotypic characteristics of mesodermal tissues. Hemangioblast, blood cell, cardiomyocyte, and vascular differentiation was impaired in EphB4–/– ES cells in conjunction with decreased expression of mesoderm-associated, but not neuroectoderm-associated, genes. Therefore, EphB4 modulates the response to mesoderm induction signals. These data add differentiation kinetics to the known effects of ephrin receptors on mammalian cell migration and adhesion. We propose that modifying sensitivity to differentiation cues is a further means for ephrin receptors to contribute to tissue patterning and organization.


2010 ◽  
Vol 134 (3) ◽  
pp. 481-485 ◽  
Author(s):  
Lobna Ayadi ◽  
Abdelmajid Khabir

Abstract Angiosarcomas are rare tumors that predominantly affect adults and elderly patients. Although angiosarcomas are well described in a variety of clinical settings, they have been poorly studied in children and little is known about their biology, natural history, or optimal treatment. Childhood angiosarcomas are exceedingly rare. The head and neck region and mediastinum seem to be the preferred locations. Most tumors are high-grade tumors. Vasoformative architecture is not always obvious on light microscopy requiring the benefit of immunohistochemical study. The differential diagnosis includes Kaposi sarcoma, epithelioid hemangioendothelioma, hemangiopericytoma, and spindle cell hemangioendothelioma whose prognosis is different. Complete resection is required for patients with localized tumors. Malignant vascular tumors are rare in children in the first 2 decades of life and when they do occur they seem to be more aggressive than in adults. Pathologic diagnosis is difficult particularly in poorly differentiated angiosarcomas requiring immunohistochemical study to confirm vascular differentiation.


Sign in / Sign up

Export Citation Format

Share Document