ISSN:
1432-0878
Keywords:
Lung
;
Turtle, Pseudemys scripta
;
Intercellular junctions
;
Freeze-fracture
;
Ultrastructure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The air-blood barrier in the lung of the turtle Pseudemys scripta was studied by means of freeze-fracture replicas in an attempt to give a detailed account on the structural organization of the intercellular junctions. Between the pneumocytes, zonulae occludentes containing 4–19 strands in the apico-basal direction are present; they are considered to be physiologically very tight. In the endothelium, fasciae occludentes, i.e., discontinuous occluding junctions can be found, composed of up to 4 strands. These junctions are regarded to be very leaky. The findings are discussed in relation to recent physiological results, suggesting that in comparison with ‘dry’ mammalian lungs, the turtle lung is a rather wet lung based on its much larger transcapillary fluid filtration into the interstitium. In addition, small maculae communicantes are demonstrated between the pneumocytes; they possibly serve for metabolic coupling.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00215783
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