Zebu (Bos indicus) ovarian preantral follicles: morphological characterization and development of an efficient isolation method

Abstract

Zebu (Bos indicus) ovarian preantral follicles: morphological characterization and development of an efficient isolation methodCarolina Madeira Lucci Rodolfo Rumpf José Ricardo Figueiredo Sonia Nair Béo AbstractPreantral follicles are a major source of oocytes, and their utilization as an important tool to store large number of female gametes for future use in reproductive programs has been investigated. The increasing importance of studies in this subject, together with the important role of Zebu cattle in the economy of tropical and subtropical countries as well as their well-known differences from European cattle, led to this research. The present study aims to determine the best size interval for sectioning ovarian tissue to isolate preantral follicles from Zebu cows using a tissue chopper and to evaluate the follicular quality after isolation. Furthermore, it aims to provide information about the Zebu cow preantral follicle population and use this data (as a control) to evaluate the effectiveness of the tested isolation method. Testing eight different tissue sectioning size intervals, it was possible to conclude that the 125-pm-section interval is shown to be better than the intervals of 25, 50, 175 and 200 pm to isolate preantral follicles from Zebu cow ovaries. The 125-pm interval allowed the recovery of 26,050±1611 (meaniS.E.M.) preantral follicles per one-half ovary, while the number of preantral follicles in situ estimated by evaluation of histological sections was 35,28812342 per one-half ovary. Thus, the mean (iS.E.M.) recovery rate (=[number of preantral follicles isolated/number of preantral follicles in situ in the same ovary] x 100) was 74.3±4.3%. The morphometrical analysis showed that Bos indicus preantral follicles are similar to B. taurus preantral follicles based on previous reports. In conclusion, this study showed that a simple, mechanical method can be used effectively to isolate a large number of intact preantral follicles from Zebu cow ovaries, with a high recovery rate.

Effect of different cryoprotectants on the structural preservation of follicles in frozen zebu bovine (Bos indicus) ovarian tissue

“…It is important to note that we used zebu (Bos indicus) ovaries, while Paynter et al [10] probably used ovaries from European bovines (Bos taurus); that may be the explanation for these differences. Similarly high percentages of morphologically normal preantral follicles were previously reported in fresh ovaries of zebu cattle (96% [23]) and other species such as goats (95% [24]), sheep (98-99% [25] and [26]), mice (91-99% [4]), and humans (73% [11]). Using 3 M DMSO or either concentration of PROH, ultrastructural evaluation revealed loss of cytoplasm content in some granulosa cells of cryopreserved follicles, but the oocytes per se displayed normal ultrastructure.…”

Effects of lowered temperatures and media on short-term preservation of zebu (Bos indicus) preantral ovarian follicles

“…4 °C for up to 18 h and 20 °C for up to 6 h), displayed changes in the oocyte that were the first degenerative signs observed (degeneration Type 1). Similar results were also observed in sheep [3] and goat [1] and [2] preantral follicles stored at 4 °C, and in fresh ovine [14], caprine [15], and bovine [16] ovaries, suggesting that this type of degeneration is commonly observed in ruminant preantral follicles. In contrast, when zebu ovaries were stored at 20 °C for 12 or 18 h, degeneration of granulosa cells (Type 2) was frequently observed, suggesting that this kind of degeneration was caused by storage.…”

“…In a morphological and functional study of mouse preantral follicles, Cortvrindt et al [21] stated that follicles with a complete disconnection between oocyte and granulosa cells suffered irreversible damage. Morphological assessment of follicular integrity has been largely used to evaluate the effectiveness of the various treatments to which ovarian follicles were subjected [1], [2], [3], [15], [16] and [21]. Although it does not replace functional tests (e.g.…”

Efeito do tipo de fixador e tempo de fixação na morfologia de folículos pré-antrais equinos

“…Preantral follicles were morphologically classified as normal or degenerated. The following aspects were considered as degeneration signs: disruption of the basement membrane, shrinking of the cytoplasm, cytoplasmic vacuoles, pyknotic nucleus and displacement of granulosa cells (LUCCI et al, 2002). analysis, with 5% of significance.…”