Mammlian oviduct is the place where the fertilization takes place and the subsequent embryonic development proceeds. To examine the possible changes in mouse extraoocyte structure in association with ovulation event, we have used fluorescein
isothiocyanate (FITC*)-casein as a marker to visualize the changes. When mouse oocytes matured in vivo were isolated from ovarian follicles at 12 hr after hCG injection and then examined for fluoresence staining of their perivitelline space
(PVS*)
with
FITC-casein, none of 52 oocytes gave a PVS staining. However, of 17 oocytes isolated from oviduct at the same age (12hr after hCG injection), 14 (about 82%) gave a distinct fluorescence staining of PVS upon treatment with the same fluorochrome.
Moreover, nearly all of oocytes and embryos, whether they were fertilized or not, gave a PVS staining when isolated from oviduct at 14hr after hCG injection or later.
When immature oocytes were explanted into the oviduct and cultured within oviduct for 20hr, they gave a PVS staining whereas oocytes cultured without oviduct did not. However, puromycin treatment to the culture medium inhibited the apperance of
fluorescence PVS staining in those oocytes cultured within oviduct in a dose dependent manner. From these observations, it is concluded that oviduct induces the changes of extraoocyte structure, which requires oviductal protein synthesis.
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