R.N. Chaves

Chilling ovarian fragments during transportation improves viability and growth of goat preantral follicles cultured in vitro

The aim of the present study was to evaluate the effects of storage of goat ovarian fragments at different temperatures and for different incubation times on the viability and growth of cultured preantral follicles in vitro. Caprine ovaries were collected and divided into 19 fragments, with one fragment being fixed immediately (fresh control). The remaining fragments were placed in minimal essential medium (MEM) and maintained at 4, 20 or 35 degrees C for 2 or 4 h. After each incubation period, some of the fragments were fixed (non-cultured), whereas others were cultured in vitro for 1 or 7 days. Fragments were processed to enable routine histological and transmission electron microscopic examination. After 7 days of culture, only ovarian fragments stored at 4 degrees C for 4 h maintained a percentage of morphologically normal follicles similar to that in the fresh control. For all other treatments groups, there was a significant increase in follicular activation observed. In addition, there was an increase in oocyte and follicular diameter after culture of ovarian cortex that had been chilled previously at 4 degrees C for 2 or 4 h. In conclusion, the present study demonstrated that chilling ovarian fragments at 4 degrees C during transportation is best for maintaining follicle viability and to increase follicular growth during in vitro culture.

Expression of follicle-stimulating hormone receptor (FSHR) in goat ovarian follicles and the impact of sequential culture medium on in vitro development of caprine preantral follicles

This study evaluated the expression of FSH receptors (FSHR) in the different stages of goat follicle development and investigated whether the addition of increasing concentrations of FSH throughout the culture period influences the survival, growth and antral formation of in vitro-cultured caprine preantral follicles. The expression of FSHR was analysed before and after culturing follicles using real-time RT-PCR. For the culture, preantral follicles (≥150 μm) were isolated from ovarian fragments and cultured for 18 days in α-MEM+ alone or associated with recombinant FSH (rFSH: 100 or 1000 ng/ml), or in α-MEM+ supplemented with increasing concentrations of FSH throughout culture periods as follows: (a) sequential medium 1: FSH 100 ng/ml (from day 0 to 6), FSH 500 ng/ml (from day 6 to 12) and FSH 1000 ng/ml (from day 12 to 18); and (b) sequential medium 2: FSH 500 ng/ml (from day 0 to 9) and 1000 ng/ml (from day 9 to 18). Follicle development was evaluated on the basis of antral cavity formation, follicular and oocyte growth, and cumulus-oocyte complex health. The expression of FSHR in isolated caprine follicles increased from the preantral to antral phase. Regarding the culture, after 18 days, sequential medium 1 promoted follicular survival, antrum formation and a reduction in oocyte extrusion. Both sequential media promoted a higher rate of meiotic resumption compared with the other treatments. In conclusion, the addition of increased concentrations of FSH (sequential medium) has a significant impact on the in vitro development of caprine preantral follicles.

In vitro survival and development of goat preantral follicles in two different oxygen tensions

The aim of the present study was to evaluate the effect of two different oxygen (O(2)) concentrations on survival and development of preantral follicles of goats cultured in vitro. Preantral ovarian follicles (> or =150 microm) were isolated from ovarian cortex fragments of goats and individually cultured for 30 days under two different O(2) concentrations (5% and 20% O(2)). Follicle development was evaluated on the basis of antral cavity formation, increase in follicular diameter, presence of healthy cumulus oocyte complexes and fully grown oocytes. Results showed with progression of culture period from 6 to 12 days, a decrease in follicular survival was observed in both O(2) concentrations (P<0.05). When the O(2) tensions were compared to each other in the different days of culture, 20% O(2) was more efficient in promoting an increase in follicular diameter from day 24 of culture onward than 5% O(2) (P<0.05). However, follicles cultured with 5% O(2) had an increased percentage of antrum formation from 12 days to the end of culture, compared with 20% O(2) (P<0.05). Moreover, there was no difference in percentage of fully developed oocytes with the different O(2) tensions. However, only oocytes (16.7%) from follicles cultured in 20% O(2) resumed meiosis. In conclusion, concentration of 20% O(2) was more efficient in promoting follicular growth and oocyte meiosis resumption from preantral follicles of goats when grown in vitro.

Short-term preservation of canine preantral follicles: effects of temperature, medium and time.

The use of the large pool of preantral follicles is a promising alternative to provide high numbers of fertilizable oocytes to reproductive biotechnology. This issue is particularly important to canids, since current rates of success of in vitro techniques using oocytes are very limited, and many species within this family are threatened by extinction. The aim of this study was to evaluate effects of temperature, medium and time on morphology and viability of canine preantral follicles during short-term preservation. Canine ovaries were cut into fragments which were incubated in 0.9% NaCl solution or in minimum essential medium (MEM) at 4, 20 or 38 degrees C for 2, 6, 12 or 24 h. Afterwards, preantral follicles were analyzed by histology, transmission electron microscopy and viability testing using trypan blue, calcein-AM and ethidium homodimer-1. Percentages of morphological normal and viable follicles were maintained similar to control (time 0 h) after incubation in 0.9% NaCl at 4 or 20 degrees C for up to 6h and at 38 degrees C for 2 h. Using MEM, such preservation was possible for 12h at 4 or 20 degrees C, and for 6h at 38 degrees C. These results indicate that preservation of canine preantral follicles might be better accomplished through hypothermic (4 or 20 degrees C) storage in MEM, which ensures maintenance of morphology and viability for up to 12h.

Steady-state level of kit ligand mRNA in goat ovaries and the role of kit ligand in preantral follicle survival and growth in vitro.

The aims of this study were to investigate steady‐state level of Kit Ligand (KL) mRNA and its effects on in vitro survival and growth of caprine preantral follicles. RT‐PCR was used to analyze caprine steady‐state level of KL mRNA in primordial, primary, and secondary follicles, and in small (1–3 mm) and large (3–6 mm) antral follicles. Furthermore, ovarian fragments were cultured for 1 or 7 days in Minimal Essential Medium (MEM+) supplemented with KL (0, 1, 10, 50, 100, or 200 ng/ml). Noncultured (control) and cultured fragments were processed for histology and transmission electron microscopy (TEM). RT‐PCR demonstrated an increase in steady‐state level of KL mRNA during the transition from primary to secondary follicles. Small antral follicles had higher steady‐state levels of KL mRNA in granulosa and theca cells than large follicles. After 7 days, only 50 ng/ml of KL had maintained the percentage of normal follicles similar to control. After 1 day, all KL concentrations reduced the percentage of primordial follicles and increased the percentage of growing follicles. KL at 10, 50, 100, or 200 ng/ml increased primary follicles, compared to MEM+ after 7 days. An increase in oocyte and follicular diameter was observed at 50 ng/ml of KL. TEM confirmed ultrastructural integrity of follicles after 7 days at 50 ng/ml of KL. In conclusion, the KL mRNAs were detected in all follicular categories. Furthermore, 50 ng/ml of KL maintained the integrity of caprine preantral follicle cultured for 7 days and stimulated primordial follicle activation and follicle growth. Mol. Reprod. Dev. 77: 231–240, 2010.

Recombinant Epidermal Growth Factor Maintains Follicular Ultrastructure and Promotes the Transition to Primary Follicles in Caprine Ovarian Tissue Cultured In Vitro

We investigated the effects of epidermal growth factor on the survival and growth of caprine preantral follicles. Ovarian fragments were cultured for 1 and 7 days in enriched minimal essential medium with epidermal growth factor (0, 1, 10, 50, 100, or 200 ng/mL). Non-cultured and cultured tissues were processed for histological and ultrastructural studies. Results showed that after 7 days, the epidermal growth factor (1 and 10 ng/mL) maintained the percentage of normal follicles similar to control. An increase in the percentage of primary follicles was observed with 1, 10, and 50 ng/mL of epidermal growth factor compared to enriched minimal essential medium. Ultrastructural studies confirmed follicular integrity after 7 days in epidermal growth factor (1 and 10 ng/mL). In conclusion, the low concentrations of epidermal growth factor maintain caprine follicular viability and promote the transition from primordial to primary follicles.

The Effects of Insulin and Follicle-Simulating Hormone (FSH) During In Vitro Development of Ovarian Goat Preantral Follicles and the Relative mRNA Expression for Insulin and FSH Receptors and Cytochrome P450 Aromatase in Cultured Follicles

ABSTRACT The actions of different concentrations of insulin alone or in combination with follicle-stimulating hormone (FSH) were evaluated by in vitro follicular development and mRNA expression of cytochrome P450 aromatase (CYP19A1) and as receptors for insulin (INSR) and FSH (FSHR) from isolated, cultured goat preantral follicles. Goat preantral follicles were microdissected and cultured for 18 days in the absence or presence of insulin (5 and 10 ng/ml or 10 μg/ml) alone or in combination with FSH. After 18 days, the addition of the maximum concentration of insulin to the culture medium reduced follicular survival and antrum formation rates significantly compared to the other treatments. However, when FSH was added to the culture medium, no differences between these two parameters were observed. Preantral and antral follicles from the fresh control as well as from all cultured follicles still presented a normal ultrastructural pattern. In medium supplemented with FSH, only insulin at 10 ng/ml presented oocytes with higher rates of meiosis resumption compared to control, as well as oocytes in metaphase II. Treatment with insulin (10 ng/ml) plus FSH resulted in significantly increased levels of INSR and CYP19A1 mRNA compared to that with other treatments. In conclusion, 10 ng/ml insulin associated with FSH was more efficient in promoting resumption of oocyte meiosis, maintaining survival, stimulating follicular development, and increasing expression of the INSR and CYP19A1 genes in goat preantral follicles. Low concentration of insulin with follicle-stimulating hormone is essential for promoting oocyte meiosis resumption in goat preantral follicles.

The fibroblast growth factor family: involvement in the regulation of folliculogenesis

Several growth factors have been identified as local regulators of follicle development and ovulation. Fibroblast growth factor (FGF) family members are potent mitogens and are involved in cell differentiation, cell migration and angiogenesis in many tissues and organs. In addition to FGF-2, which is the most-studied FGF, other important members are FGF-1, -5, -7, -8, -9 and -10. A number of studies have indicated that FGFs play important roles in regulating the initiation of primordial follicle growth, oocyte and follicle survival, granulosa and theca cell proliferation and differentiation, corpus luteum formation, steroidogenesis and angiogenesis. The purpose of this review is to highlight the importance of the FGFs on mammalian female reproduction, providing a better understanding of the roles of this family in ovarian physiology and female fertility.

Interaction between growth differentiation factor 9, insulin-like growth factor I and growth hormone on the in vitro development and survival of goat preantral follicles

The objective of this study was to determine the effects of GDF-9, IGF-I, and GH alone or combined on preantral follicle survival, activation and development after 1 and 7 days of in vitro culture. Either fresh (non-cultured) or cultured ovarian tissue was processed for histological and fluorescence analysis. For all media tested, the percent of normal follicles was greater when compared to minimum essential medium supplemented (MEM+) alone, except when ovarian tissue was cultured with GDF-9/IGF-I or GDF-9/GH (P < 0.05). Fluorescence analysis showed that the percent of viable follicles after 7 days of culture was similar for non-cultured tissue and for all treatments tested. The percent of primordial follicles was reduced (P < 0.05) and there was a significant and concomitant increase in the percent of intermediate and primary follicles in all treatments tested after 7 days of culture when compared to non-cultured tissue. After 7 days of culture, the highest percent of intermediate follicles was observed with IGF-I/GH (61.3%), and the highest percent of primary follicles was achieved with IGF-I (57.7%). After 7 days of culture in MEM+ containing GDF-9, IGF-I and GH alone or in all associations, a significant increase in follicular diameter was observed when compared to MEM+ alone and non-cultured tissue. In conclusion, GDF-9, IGF-I and GH alone or in combination maintain preantral follicle survival and promote primordial follicle activation. Nevertheless, the data showed that IGF-I/GH and IGF-I alone are efficient in promoting the transition from primordial to intermediate follicles and from intermediate to primary follicles, respectively.

In vitro development of secondary follicles from pre-pubertal and adult goats cultured in two-dimensional or three-dimensional systems

The aim of this study was to evaluate the influence of two-dimensional (2D) and three-dimensional (3D) alginate culture systems on in vitro development of pre-antral caprine follicles. In addition, the influence of the reproductive age of the ovary donor on the in vitro culture success was investigated. Pre-antral follicles from pre-pubertal or adult goats were isolated and cultured directly on a plastic surface (2D) or encapsulated in an alginate-based matrix (3D). After 18 days, the oocytes underwent in vitro maturation (IVM) and in vitro fertilization (IVF) to produce embryos. The 3D system showed higher rates of follicle survival, lower rates of oocyte extrusion, and a greater number of recovered oocytes for IVM and IVF (P < 0.05). Only pre-antral follicles from adult animals produced MII oocytes and embryos. The estradiol concentrations increased from day 2 to day 12 of culture in all groups tested (P < 0.05). Conversely, progesterone concentrations were lower in 3D-cultured follicles than in 2D-cultured follicles, with differences on days 2 and 6 of culture (P < 0.05). We provide compelling evidence that a 2D or 3D alginate in vitro culture system offers a promising approach to achieving full in vitro development of caprine pre-antral follicles to produce mature oocytes that are capable of fertilization and viable embryos.