Biography:

One of their most recent publications is Research articleCharacterization of folliculogenesis and the occurrence of apoptosis in the development of the bovine fetal ovary. Which was published in journal Theriogenology.

More information about S.S.D. Santos research including statistics on their citations can be found on their Copernicus Academic profile page.

S.S.D. Santos's Articles: (2)

Research articleCharacterization of folliculogenesis and the occurrence of apoptosis in the development of the bovine fetal ovary

AbstractThe aim of this research was to perform in situ quantification, morphometry evaluation, and apoptosis analysis of ovarian follicular wall cells in mechanically isolated follicles obtained from ovaries of bovine fetuses (Bos taurus indicus) between 3 and 9 months of age. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The number of isolated follicles increased from 3 months onward (102.5 ± 141.1, mean ± SEM), peaked at 6 months (12855.0 ± 9030.1), and then decreased by 7 months (3208.7 ± 3249.5), consistent with atresia occurring at these stages. Follicular density was greatest at 4 months, consistent with a sudden boost in follicular activity independent of a corresponding increase in ovarian size. Antral follicles were first observed at 5 months. As fetal age increased, there was a tendency for the percentage of primordial and primary follicles to decrease, and the percentage of secondary follicles to increase. However, the high variability (P < 0.05) for all follicle populations up to 5 months of age precluded further interpretation of these results. Oocyte diameter increased from the primordial (23.6 ± 4.4 μm) to the secondary follicular stages (38.0 ± 14.9 μm). Apoptosis was observed in ovaries from all fetal ages analyzed. We concluded that preantral follicles could be isolated from bovine fetuses by 3 months of age, with apoptosis affecting ovarian follicular dynamics throughout fetal life.

Isolation, follicular density, and culture of preantral follicles of buffalo fetuses of different ages

AbstractThe aim of the present study was to determine the most desirable ovarian tissue section thickness to isolate preantral follicles (Experiment I), determine follicular density (follicles/mm2 of cortex) of ovaries of fetal buffalo of different ages (Experiment II), and cultivate preantral follicles of buffalo fetuses (Experiment III). In Experiment I, ovary sections with different thicknesses (25, 50, 75, and 100 μm) had 415.0 ± 285.2, 457.5 ± 341.9, 585.0 ± 309.3, and 685.0 ± 278.8 isolated preantral follicles, respectively. In Experiment II, the follicular density of 46 buffalo fetuses with ages between 3 and 8 months was estimated to be between 0 and 7220, with means of 0.0, 2070.7 ± 2190.3, 2570.8 ± 1796.6, 2298.1 ± 2286.5, 1277.5 ± 1074.9, and 643.6 ± 543.9 throughout the age range studied. The follicular density of 5-month-old fetuses was greatest, coinciding with the largest number of follicles isolated at this age. In Experiment III, preantral follicles isolated from the ovaries of buffalo fetuses aged from 5 to 9 months old were cultivated individually for 7 days in four different media: basic medium (Minimal Essential Medium (MEM), 10% SFB, kanamycin, pyruvate, glutamine, hypoxanthine) with additional ITS and FSH 0.5 mg/ml (treatment 1); basic medium with FSH and EGF 100 ng/ml (treatment 2); basic medium with additional ITS, FSH, and EGF (treatment 3); basic medium supplemented with ITS and EGF (treatment 4). Integrity and morphological features, viability, and increase in diameter of follicles cultured in vitro were evaluated individually with an inverted microscope and an ocular micrometer. The results showed that follicle structure and form were maintained during culture. Growth and survival rates of treatments 1, 2, and 3 over 7 day culture were 23.25 ± 17.06, 33.75 ± 26.19, and 43.75 ± 31.73 μm, and 31.3 ± 22.7, 22.06 ± 8.13, and 28.92 ± 21.32%, respectively. However, neither growth nor survival was observed in treatment 4. In conclusion, this study showed that preantral follicles of buffalo fetuses can be cultured in vitro, and that FSH is essential for follicle survival.

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