Fig. 2

Assessment of ubiquitin in mature oocytes. Left panel shows phase-contrast images of analyzed oocytes, center panel displays the corresponding confocal fluorescent images with pseudocolor and right panel the merged images of the phase-contrast image and the fluorescence image. Human oocytes discarded from assisted reproduction techniques were collected and kept frozen until use for immunofluorescence studies for detection of (a) ZP; (b) Ub; (c) No primary detection (negative control without primary antibody); (d) Antibody competence (Anti-Ub antibodies + Ub protein). (e) Mouse oocytes obtained from hyperstimulated females were used as positive control by incubating with anti-Ub as positive control. Specific staining for Ub was detected in the ZP of both species