ISSN:
1432-0878
Keywords:
Uterus (myometrium)
;
Gap junctions
;
Pregnancy
;
Morphometry
;
Freeze-fracturing
;
Rat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary In uterine smooth muscles, gap junction plaques rapidly form during the final stages of gestation. To investigate the related mechanisms, regional differences in myometrial gap junction development in rat uterus were examined quantitatively during delivery, using thin-section and freeze-fracture techniques in combination with light- and electron microscopy. Examination of implanted and nonimplanted horns in the unilaterally ligated rat bicornuate uteri, revealed no differences in the occurrence of gap junction plaques, but after 2 to 4 pups had been delivered, the contracted segments contained more gap junction plaques than did noncontracted segments examined immediately before delivery. In all segments, gap junctions were found more frequently in the circular muscle layers than in the longitudinal muscle layers. Gap junctions ranged in size from 0.002 μm2 to 0.52 μm2, but two-thirds were less than 0.1 μm2. The frequency of small gap junction plaques (less than 0.1 μm2) was higher in the noncontracted segment. These results suggest that gap junctions are dynamic structures, and that their formation is controlled not only by general hormonal factors, possibly involved in gap junction increases in the myometrium before delivery, but also by local factors, possibly related to the contraction, that may accelerate an increase in gap junction formation during delivery.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00218196
