High-Resolution Ultrasonography of Xenografted Domestic Cat Ovarian Cortex

Abstract

Abstract. Transplantation of ovarian tissue has high potential for female gamete conservation. However, optimal timing of oocyte recovery for in vitro maturation and fertilization is still critical. Therefor the aim of the present study was to use high-resolution transcutaneous ultrasonography to monitor follicular development within xenografted ovarian tissue. Ovarian cortex fragments (n=44) from domestic cats were transplanted into athymic nude rats (n=12). Graft development in the animals was assessed weekly by high frequency ultrasound (10-22 MHz) under two different FSH regimes. Blood collection for serum estradiol determination and vaginal smears were performed simultaneously. The xenografts were removed at different time points according to the ultrasound findings. The survival rate of the transplants 4 weeks after surgery was 54.5% and antral follicular growth was observed within 10 grafts from 5 different hosts (8.6 ± 6.43 follicles per graft). Early follicle antrums could be detected from 0.4 mm onwards. The growth rate of the antral cavity was calculated from weekly measurements (0.56 ± 0.44 mm per week). Although vaginal cells and estradiol levels followed a cyclic pattern, no correlation was found between follicular diameter, estradiol and keratinized vaginal cells. We recovered 5, 1 and 4 cumulus oocyte complexes from three different individuals during weeks 19, 21, and 23 respectively. Extrusion of a polar body (1 oocyte) and germinal vesicle break down (7 oocytes) indicated progression of maturation after in vitro culture. We conclude that ultrasonography und provided a reliable method to examine xenograft survival and follicular development within the grafts. Furthermore, this technique is suitable for assessment of the efficiency of hormonal treatment and narrowing of the optimal time frame for oocyte retrieval. To our knowledge, this is the first report of the in vivo development of early antral follicles in mammalian species.

Preservation of Primordial Follicles from Lions by Slow Freezing and Xenotransplantation of Ovarian Cortex into an Immunodeficient Mouse

“…A potentially better approach will be to use all COCs to establish the necessary methods for oocytes cryopreservation and embryo production, as a prerequisite for handling oocytes obtained from ovarian tissue after xenotransplantation (Fassbender et al. ).…”

Short-term culture of ovarian cortex pieces to assess the cryopreservation outcome in wild felids for genome conservation

“…Our group used BrdU-labeling and Hoechst staining for integrity assessment of mechanical isolated preantral follicles to control culture impacts [21], but it was shown that the procedure of isolation from the ovarian cortex itself can cause a loss of integrity in primordial follicles [22]. We also suggested the application of high-resolution ultrasound to monitor the survival of fresh ovarian xenotransplants in immunodeficient recipients as a prerequisite for oocytes retrieval [15]. The freezing of isolated preantral follicles as well as COCs is not well established yet for felid species.…”

“…Bosch et al [14] demonstrated the successful cryopreservation of domestic cat ovarian cortex in conjunction with xenotransplantation into nude mice. However, feline oocytes seem to express a higher sensitivity towards cryopreservation protocols [15,16] than other mammalian oocytes.…”

Utilization of Oocytes Collected from Preserved Ovarian for In Vitro Production of Cat Embryos

“…Yasmin et al (2015) confirmed that the meiotic spindles in bovine oocytes are very sensitive to low temperatures that can affect the level of maturation and fertilization. Feline oocytes seem to express a higher sensitivity to chilling (Fassbender et al, 2007).…”

“…A cryopreservation protocol has been developed for preserving cat ovarian tissues with minimum effect on the survival of the follicles (Giaretta et al, 2013). However, feline oocytes seem to express a higher sensitivity towards cryopreservation protocols (Fassbender et al, 2007). Shorter preservation procedures using physiological solutions such as PBS stored at 4-5°C can provide an alternative way to save the source of germ cells such as ovary and testes.…”