Erratum: Organization of the adluminal and retractor cells in the coelomic lining from the tube foot of a phanerozonian starfish, Luidia foliolata

1991 ◽  
Vol 69 (7) ◽  
pp. 1976-1976
Author(s):  
Michael J. Cavey ◽  
Richard L. Wood
Keyword(s):  
Development ◽  
1976 ◽  
Vol 35 (1) ◽  
pp. 125-138
Author(s):  
C. C. Wylie ◽  
J. Heasman

In Xenopus laevis tadpoles, between stages 44 and 49 (Nieuwkoop & Faber, 1956), the primordial germ cells (PGCs) migrate from the dorsal mesentery of the gut to the site of the presumptive gonadal ridge. This paper describes the process at the light- and electronmicroscope levels. The PGCs in the mesentery, which at first are very large and yolk-laden, seem to lie entirely within the cellular matrix of the mesentery, although this is not obvious in light micrographs. Where the PGCs bulge out into the coelomic cavity, they stretch the somatic cell covering to a thin, cytoplasmic layer. The somatic cells of the mesentery are held together around them at this stage by well-differentiated desmosomes. At this, and subsequent stages, the PGCs have cytoplasmic processes, roughly the size of microvilli, which are irregularly distributed over their surfaces, and which are inserted between surrounding somatic cells. Whether these processes play any role in locomotion or exploration of the substrate is uncertain. As the PGCs move laterally from the root of the mesentery to the presumptive gonadal ridge, the coelomic lining cells which cover them, initially with a very thin squamous layer, differentiate to form the cuboidal cells of the germinal epithelium. Several interesting ultrastructural features of these cells, and the PGCs, are described, particularly in the light of their surface interaction. In the light of the morphological data presented here, particularly of the cell surfaces involved, we conclude that both active locomotion by the PGCs and passive movement by the morphogenetic movements of the cells around them contribute to the establishment of the early gonadal ridge.


2017 ◽  
Vol 61 (3-4-5) ◽  
pp. 329-335 ◽  
Author(s):  
Alaa A. Arraf ◽  
Marella F. T. R. De Bruijn ◽  
Thomas M. Schultheiss

2012 ◽  
Vol 15 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Christine K.C. Loo ◽  
Elizabeth M. Algar ◽  
Diane J. Payton ◽  
Joanna Perry-Keene ◽  
Tamara N. Pereira ◽  
...  

The association of peripheral bronchial atresia and congenital pulmonary airway malformation (CPAM) has recently been recognised, but the pathology of the lesions evolving together has not been described. We present autopsy findings in a 20 week fetus showing areas of peripheral bronchial destruction and airway malformation consistent with developing CPAM in the right lung supporting a causal relationship between these lesions. This fetus also had congenital heart defect, bilateral renal agenesis and syndactyly. We identified another fetus from our autopsy files, with bilateral renal agenesis, similar right sided pulmonary malformation and cardiac defects. Similar bilateral renal agenesis and defects of the heart and lungs are found in wt1−-/– mice and we have investigated the expression of WT1 in these fetuses. We hypothesise that the cardiac, liver, renal and possibly lung lesions in these two cases may arise due to mesenchymal defects consequent to WT1 misexpression and discuss evidence for this from the scientific literature. We used immunoperoxidase stains to analyse WT1 expression in autopsy hepatic tissue in both fetuses. We also investigated the expression of α-smooth muscle actin (α-SMA), a marker of activated hepatic stellate cells/myofibroblasts, and desmin in hepatic mesenchyme and compare these findings with control fetuses, without congenital malformations. We found reduced WT1 expression in hepatic mesothelium in both fetuses with malformations. There was also increased expression of α-SMA in liver perisinusoidal cells, as seen in the wt1−-/– mouse model. We therefore propose that abnormality of WT1 signalling may be an underlying factor, as WT1 is expressed in coelomic lining cells from which mesenchyme is derived in many organs.


Development ◽  
1976 ◽  
Vol 35 (1) ◽  
pp. 139-148
Author(s):  
C. C. Wylie ◽  
M. Bancroft ◽  
J. Heasman

This paper studies the surface morphology of the developing gonadal ridge in X. laevis between stages 44 and 49 (Nieuwkoop & Faber, 1956). During this period the primordialgerm cells (PGCs) move laterally from the dorsal mesentery of the gut to the position of thepresumptive gonadal ridge. As they do so the coelomic lining cells lateral to the mesenterydifferentiate into a specialized, longitudinally orientated band, stretching nearly the fulllength of the dorsal mesentery on each side. The PGCs migrate beneath this band of cells, which thus becomes the germinal epithelium of the gonadal ridge. We have demonstrated by irradiation experiments that this specialized band of cells can differentiate independently, in the absence of the PGCs.


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