Preservation of preantral follicles becomes very important to ensure follicle quality at the onset of cryopreservation or in vitro culture. However, for domestic animals, the ovarian donor of preantral follicles for in vitro studies is commonly encountered far away from reproduction laboratories. We investigated the effectiveness of coconut water and BraunCollins solutions on the preservation of goat preantral follicles. At the slaughterhouse, the ovarian pair of each animal was divided into 19 fragments. One ovarian fragment was immediately fixed (Control -Time 0). The other 18 fragments were randomly distributed into tubes containing 2 mL of coconut water or Braun-Collins solution at 4 °, 20 ° or 39 °C and then stored for 4, 12 or 24 h. Histological analysis showed that the storage of ovarian fragments in coconut water and Braun-Collins solutions at 20 ° or 39 °C for 12 or 24 h significantly reduced (P < 0.05) the percentage of morphologically normal preantral follicles when compared with the control. However, storage in coconut water at 20 °C for 4 h and in both solutions at 4 °C kept the percentage at control values. Ultrastructural analysis of follicles exposed to the stated conditions confirmed the integrity of preantral follicles stored at 4 °C in Braun-Collins and coconut water solutions for up to 12 and 24 h, respectively. Reduced cellular metabolism at 4 °C may explain why the best preservation of preantral follicles was at 4 °C, which may suggest a useful method for ovary transport in the future.

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The present work has investigated the morphological and ultrastructural changes occurring during degeneration of goat preantral follicles preserved in vitro and showed quantitative data about the distribution of follicular degeneration types in the control and after preservation in coconut water solution or Braun-Collins solution at different temperatures (4, 20 or 39°C) and incubation times (4, 12 or 24 h). At the slaughterhouse, the pair of ovaries of each animal was divided into 19 fragments. One ovarian fragment was immediately fixed (control: Time 0). The other 18 fragments were randomly distributed in tubes containing 2 ml of coconut water or Braun-Collins solution at 4, 20 or 39°C and stored for 4, 12 or 24 h. Normal preantral follicles exhibited a healthy oocyte surrounded by one or more well-organized layers of granulosa cells. The ooplasm contained numerous rounded or elongated mitochondria with continuous mitochondrial membranes. Golgi complexes were rare. Both smooth and rough endoplasmic reticulum were observed, either as isolated aggregations or complex associations with mitochondria and vesicles. Degenerated preantral follicles in the control tissue exhibited pycnotic nuclei of the oocyte, vacuolated ooplasm and normal granulosa cells. This kind of degeneration also predominated significantly (P<0.05) after preservation at 4°C. In contrast, after preservation at 20 or 39°C a significant predominance (P<0.05) of preantral follicles showing a retracted oocyte and swollen granulosa cells was observed. These follicles showed large irregularity of the oocyte and nuclear outlines. The ooplasm exhibited moderate proliferation of the endoplasmic reticulum and mitochondria showed disappearance of most of the cristae and damage to the mitochondrial membrane. Some follicles had numerous vacuoles in the ooplasm. Granulosa cells were spread and a low density of organelles was observed. The alterations in follicular structure progressed with an increase of temperature from 20 to 39°C as well as with an increase of the incubation time from 4 to 12, or 24 h. In conclusion, the present study shows for the first time that initial proliferation of the endoplasmic reticulum and damage to mitochondria are the first signs of degeneration in goat preantral follicles during storage in vitro.

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