In:
Journal of Experimental Zoology, Wiley, Vol. 242, No. 1 ( 1987-04), p. 35-42
Abstract:
The primary objectives of this study were (1) to determine the embryonic stage at which the Oryzias latipes enveloping layer (EVL) begins to contract rhythmically, and (2) to determine where these contractions arise within the EVL. Using time‐lapse video recording, we showed that the contractions begin at stage 14 (the stage of the embryonic shield) and arise in the ventral region of the EVL, which is centered at 180° longitude from the embryonic shield. We have called this the pacemaker region for the contractions. Using fluorescein diacetate as a vital stain, we showed that the ventral region of the EVL continues to act as a pacemaker even after the EVL is detached from the rest of the egg. Rhythmic contractile activity ceased when we removed a group of about 130 cells — 10% of the total EVL— from the pacemaker region; comparably large wounds elsewhere had no effect on the contractions. When we cut detached EVLs into ten pieces, only 2.4 ± 1.8 (X ± SD, N = 11) of them contracted rhythmically, even though a considerably larger proportion of the EVL cells participate in the contractions in undisturbed blastoderms. We conclude that the pacemaker cells are necessary for rhythmic contractile activity and that cells outside this region do not contract spontaneously. The contractile waves are propagated at a velocity of 14–54 μm sec −1 . This value, which is two to three orders of magnitude slower than the propagation of epithelial action potentials, is similar to the rate of propagation of waves of increased cytosolic Ca 2+ in other systems. We propose that the medaka EVL is a good system in which to study certain aspects of epithelial morphogenesis.
Type of Medium:
Online Resource
ISSN:
0022-104X
,
1097-010X
DOI:
10.1002/jez.1402420106
Language:
English
Publisher:
Wiley
Publication Date:
1987
detail.hit.zdb_id:
2205981-7
SSG:
12
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