scholarly journals Ultrastructure of the coelomic lining in the podium of the starfish Stylasterias forreri

1981 ◽  
Vol 218 (3) ◽  
Author(s):  
RichardL. Wood ◽  
MichaelJ. Cavey
Keyword(s):  
Coelomic Lining

The formation of the gonadal ridge in Xenopus laevis

Development ◽  
1976 ◽  
Vol 35 (1) ◽  
pp. 125-138
Author(s):  
C. C. Wylie ◽  
J. Heasman
Keyword(s):  
Xenopus Laevis ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Passive Movement ◽  
Morphological Data ◽  
Cell Surfaces ◽  
Coelomic Cavity ◽  
Coelomic Lining ◽  
Well Differentiated ◽  
Cytoplasmic Processes

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.

scholarly journals Disruption of the aortic wall by coelomic lining-derived mesenchymal cells accompanies the onset of aortic hematopoiesis

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

Possible Role of WT1 in a Human Fetus with Evolving Bronchial Atresia, Pulmonary Malformation and Renal Agenesis

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 ◽  
...  
Keyword(s):  
Scientific Literature ◽  
Renal Agenesis ◽  
Smooth Muscle Actin ◽  
Hepatic Tissue ◽  
Congenital Pulmonary Airway Malformation ◽  
Underlying Factor ◽  
Coelomic Lining ◽  
The Right ◽  
Bronchial Atresia

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.

The formation of the gonadal ridge in Xenopus laevis

Development ◽  
1976 ◽  
Vol 35 (1) ◽  
pp. 139-148
Author(s):  
C. C. Wylie ◽  
M. Bancroft ◽  
J. Heasman
Keyword(s):  
Surface Morphology ◽  
Xenopus Laevis ◽  
Germinal Epithelium ◽  
Coelomic Lining ◽  
Dorsal Mesentery ◽  
Do So

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.

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

1991 ◽  
Vol 69 (4) ◽  
pp. 911-923 ◽  
Author(s):  
Michael J. Cavey ◽  
Richard L. Wood
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Connective Tissue ◽  
Basal Lamina ◽  
Freeze Fracture ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Primitive Species ◽  
Ultrathin Sections ◽  
Coelomic Lining ◽  
Tube Feet

The coelomic lining in the tube feet of the phanerozonian starfish Luidia foliolata is a complex pseudostratified myoepithelium consisting largely of flagellated adluminal cells and myofilament-bearing retractor cells. The adluminal cells, joined by zonular intermediate and septate junctions, line the water–vascular canal. Basal processes of the adluminal cells penetrate the underlying layers of retractor cells to terminate as bulbous pedicels at the myoepithelial basal lamina. The longitudinally oriented retractor cells, linked by macular and fascial intermediate junctions, also direct processes obliquely to the basal lamina for anchorage. In keeping with its myoepithelial classification, the coelomic lining of the tube foot is devoid of connective tissue. The organization of the coelomic lining in this primitive species has not substantively improved our understanding of the events of excitation–contraction coupling. Both the coelomic lining and the podial connective tissue lack nerves, and there is no ultrastructural evidence of communicating (gap) junctions between the retractor cells. The sarcoplasmic reticulum of a retractor cell is a plexiform network of agranular cisternae lodged between the contractile apparatus and the sarcolemma. Peripheral couplings between the sarcoplasmic reticulum and the sarcolemma can be identified in ultrathin sections by the presence of electron-dense plaques in the sarcoplasmic gaps between the apposed membranes. In freeze-fracture replicas, the placement of these structural couplings is correlated with aggregations of large intramembranous particles over regions of cisternal confluence. Conceptual problems in understanding excitation–contraction coupling in a modern starfish are compounded in this primitive representative by the presence of many more layers of retractor cells and by a burrowing life-style which requires the tube feet to respond in a rapid, highly coordinated manner.

Sign in / Sign up

Export Citation Format

Share Document