TY - JOUR
T1 - Subcellular distribution of ZP1, ZP2, and ZP3 glycoproteins during folliculogenesis and demonstration of their topographical disposition within the zona matrix of mouse ovarian oocytes
AU - El-Mestrah, Majid
AU - Castle, Philip E.
AU - Borossa, Girum
AU - Kan, Frederick W.K.
PY - 2002
Y1 - 2002
N2 - The zona pellucida (ZP) is an extracellular coat synthesized and secreted by the oocyte during follicular development and surrounding the plasma membrane of mammalian eggs. To date, the mechanism of synthesis and secretion, mode of assembly, and intracellular trafficking of the ZP glycoproteins have not been fully elucidated. Using antibodies against mouse ZP1, ZP2, and ZP3 in conjunction with the protein A-gold technique, we have shown an association of immunolabeling with the Golgi apparatus, secretory granules, and a complex structure called vesicular aggregate, respectively, in mouse ovarian follicles. In contrast, the neighboring granulosa cells were not reactive to any of the three antibodies used. Immunolabeling of ZP1, ZP2, and ZP3 was detected throughout the entire thickness of the ZP, irrespective of the developmental stage of ovarian follicles. Double and triple immunolocalization studies, using antibodies tagged directly to different sizes of gold particles, revealed an asymmetric spatial distribution of the three ZP glycoproteins in the zona matrix at various stages of follicular development. All three glycoproteins were specifically localized over small patches of darkly stained flocculent substance dispersed throughout the zona matrix. Very often, ZP1, ZP2, and ZP3 were found in close association. These results confirm findings from previous studies demonstrating that ovarian oocytes and not granulosa cells are the only source for mouse ZP glycoproteins. In addition, results from our morphological and immunocytochemical experiments suggest that the vesicular aggregates in the ooplasm are likely to serve as an intermediary in the synthesis and secretion of ZP glycoproteins. The stoichiometric disposition of ZP1, ZP2, and ZP3 in the zona matrix as revealed by double and triple immunolocalization studies provide further insight into some of the unanswered questions pertinent to the current model of mouse ZP structure proposed by the Wassarman group.
AB - The zona pellucida (ZP) is an extracellular coat synthesized and secreted by the oocyte during follicular development and surrounding the plasma membrane of mammalian eggs. To date, the mechanism of synthesis and secretion, mode of assembly, and intracellular trafficking of the ZP glycoproteins have not been fully elucidated. Using antibodies against mouse ZP1, ZP2, and ZP3 in conjunction with the protein A-gold technique, we have shown an association of immunolabeling with the Golgi apparatus, secretory granules, and a complex structure called vesicular aggregate, respectively, in mouse ovarian follicles. In contrast, the neighboring granulosa cells were not reactive to any of the three antibodies used. Immunolabeling of ZP1, ZP2, and ZP3 was detected throughout the entire thickness of the ZP, irrespective of the developmental stage of ovarian follicles. Double and triple immunolocalization studies, using antibodies tagged directly to different sizes of gold particles, revealed an asymmetric spatial distribution of the three ZP glycoproteins in the zona matrix at various stages of follicular development. All three glycoproteins were specifically localized over small patches of darkly stained flocculent substance dispersed throughout the zona matrix. Very often, ZP1, ZP2, and ZP3 were found in close association. These results confirm findings from previous studies demonstrating that ovarian oocytes and not granulosa cells are the only source for mouse ZP glycoproteins. In addition, results from our morphological and immunocytochemical experiments suggest that the vesicular aggregates in the ooplasm are likely to serve as an intermediary in the synthesis and secretion of ZP glycoproteins. The stoichiometric disposition of ZP1, ZP2, and ZP3 in the zona matrix as revealed by double and triple immunolocalization studies provide further insight into some of the unanswered questions pertinent to the current model of mouse ZP structure proposed by the Wassarman group.
KW - Female reproductive tract
KW - Fertilization
KW - Follicle
KW - Oocyte development
KW - Ovary
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U2 - 10.1095/biolreprod66.4.866
DO - 10.1095/biolreprod66.4.866
M3 - Article
C2 - 11906903
AN - SCOPUS:0036195795
SN - 0006-3363
VL - 66
SP - 866
EP - 876
JO - Biology of Reproduction
JF - Biology of Reproduction
IS - 4
ER -