In vitro culture of equine preantral follicles obtained via the Biopsy Pick-Up method

Number and density of equine preantral follicles in different ovarian histological section thicknesses

“…Therefore, besides allowing detection of more follicles, the 7-mm treatment was also efficient in terms of evaluating follicular morphology. Furthermore, the overall rate of morphological normal follicles (89%) was similar to that reported in previous studies in mares [7][8][9]. In addition, the proportion of preantral follicle classes and their morphometrical characteristics were also similar to those in the aforementioned studies.…”

“…Previous studies on equine ovarian tissue have used section thicknesses of 5 mm [16,25], 7 mm [6], and 10 mm [8,9,11] to evaluate preantral follicles. However, no study has reported the efficiency of different histological section thicknesses on equine preantral follicle population and density under the same experimental conditions.…”

“…In the horse, distinct from other species, this process requires vigorous flushing and scraping of the follicle wall using ultrasonography [3]. As an alternative method to overcome this limitation, and considering that preantral follicles are of great abundance in the ovary, studies in our laboratory recently validated the use of a transvaginal ultrasoundguided ovarian biopsy pick up method to harvest preantral follicles in mares [7][8][9].…”

“…At this moment, a limited number of studies have reported on equine preantral follicle population; these reports have suggested the presence of a low number of preantral follicles in the ovary when compared with other species [7][8][9][10][11]. Therefore, studies on equine preantral follicle population and density are necessary to facilitate the development of ARTs using immature oocytes enclosed in preantral follicles.…”

“…The histological section thickness can influence the evaluation of preantral follicle population. Studies in this area used different section thicknesses (e.g., 3 mm: mice [14]; 5 mm: ovine [15], equine [16]; 6 mm: ovine [17]; 7 mm: caprine [18], bovine [19]; or 10 mm: women [20], equine [8][9][10]). These studies reported the lack of a standardization for histological section thickness preparations even within the same species (e.g., ovine [21,22]).…”