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Cytochemical Ca 2+ Distribution in Activated Discoglossus pictus Eggs: A Gradient in the Predetermined Site of Fertilization
Author(s) -
Gualtieri Roberto,
Campanella Chiara,
Andreuccetti Piero
Publication year - 1992
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1992.tb00002.x
Subject(s) - endoplasmic reticulum , egta , human fertilization , biophysics , chemistry , biology , calcium , anatomy , biochemistry , organic chemistry
The K‐pyroantimonate/OsO 4 (PA) cytochemical method coupled with EGTA and X‐ray microanalytical controls has been used to localize Ca 2+ at egg activation in Discoglossus pictus eggs. The results show that: 1) the PA method is able to selectively localize Ca 2+ pools mobilized by activating stimuli; 2) the smooth endoplasmic reticulum (SER) elements located in the animal dimple region, i.e. in the predetermined site of fertilization, are the first egg components labeled by precipitates; 3) a decreasing gradient of precipitates is present from the center beyond the boundaries of the dimple region; 4) precipitates are lacking in the remainder of the egg even at late times after activation. The possibilities are discussed that a) SER is the major Ca 2+ ‐releasing store at activation in Discoglossus , and b) the observed gradient of pyroantimonate‐detected Ca 2+ reflects an ionic Ca 2+ gradient.