In vitro development of marmoset monkey oocytes by pre-antral follicle culture

Female fertility preservation strategies: cryopreservation and ovarian tissue in vitro culture, current state of the art and future perspectives

In the present review, the main strategies of female fertility preservation are covered. Procedures of fertility preservation are necessary for women who suffer from diseases whose treatment requires the use of aggressive therapies, such as chemotherapy and radiotherapy. These kinds of therapy negatively influence the health of gametes and their progenitors. The most commonly used method of female fertility preservation is ovarian tissue cryopreservation, followed by the retransplantation of thawed tissue. Another approach to female fertility preservation that has been actively developed lately is the ovarian tissue in vitro culture. The principal methods, advantages and drawbacks of these two strategies are discussed in this article.

Amphibian (Euphlyctis cyanophlyctis) in vitro ovarian culture system to assess impact of aquatic agrochemical contaminants on female reproduction

The present study is an attempt to screen impacts of aquatic agrochemical contaminants (acephate, atrazine and cypermethrin) on development and growth of follicles, in in vitro-cultured ovarian fragments of frog (Euphlyctis cyanophlyctis). Ovarian lobes removed surgically from gravid females were cut into small pieces and cultured in vitro in presence of graded (0.01 or 0.1 μg/ml of culture medium) concentrations of test chemicals or estradiol-17β (positive controls) or culture medium alone (controls) in quadruplicate sets at 23 ± 1 °C temperature for 20 days in a humidified sterile chamber. On 21st day, they were fixed in Bouin's fluid and used for differential follicle counting (n = 3 sets) and histology (n = 1 set). In vitro exposure of ovarian fragments to test chemicals caused a decline in previtellogenic follicles, maintenance of large yolky follicles, incorporation of brown granules into early vitellogenic follicles and decrease in follicular atresia compared to corresponding controls. These results suggest that ovarian follicles are greatly sensitive to chemical exposure during their transition from previtellogenic to vitellogenic growth phase and in vitro ovarian culture system may be used as a tool to assess the effects of aquatic agrochemical contaminants on ovarian function.

Promoting extracellular matrix remodeling via ascorbic acid enhances the survival of primary ovarian follicles encapsulated in alginate hydrogels

The in vitro growth of ovarian follicles is an emerging technology for fertility preservation. Various strategies support the culture of secondary and multilayer follicles from various species including mice, non-human primate, and human; however, the culture of early stage (primary and primordial) follicles, which are more abundant in the ovary and survive cryopreservation, has been limited. Hydrogel-encapsulating follicle culture systems that employed feeder cells, such as mouse embryonic fibroblasts (MEFs), stimulated the growth of primary follicles (70-80 µm); yet, survival was low and smaller follicles (<70 µm) rapidly lost structure and degenerated. These morphologic changes were associated with a breakdown of the follicular basement membrane; hence, this study investigated ascorbic acid based on its role in extracellular matrix (ECM) deposition/remodeling for other applications. The selection of ascorbic acid was further supported by a microarray analysis that suggested a decrease in mRNA levels of enzymes within the ascorbate pathway between primordial, primary, and secondary follicles. The supplementation of ascorbic acid (50 µg/mL) significantly enhanced the survival of primary follicles (<80 µm) cultured in alginate hydrogels, which coincided with improved structural integrity. Follicles developed antral cavities and increased to diameters exceeding 250 µm. Consistent with improved structural integrity, the gene/protein expression of ECM and cell adhesion molecules was significantly changed. This research supports the notion that modifying the culture environment (medium components) can substantially enhance the survival and growth of early stage follicles.

Primate follicular development and oocyte maturation in vitro

The factors and processes involved in primate follicular development are complex and not fully understood. An encapsulated three-dimensional (3D) follicle culture system could be a valuable in vitro model to study the dynamics and regulation of folliculogenesis in intact individual follicles in primates. Besides the research relevance, in vitro follicle maturation (IFM) is emerging as a promising approach to offer options for fertility preservation in female patients with cancer. This review summarizes the current published data on in vitro follicular development from the preantral to small antral stage in nonhuman primates, including follicle survival and growth, endocrine (ovarian steroid hormone) and paracrine/autocrine (local factor) function, as well as oocyte maturation and fertilization. Future directions include major challenges and strategies to further improve follicular growth and differentiation with oocytes competent for in vitro fertilization and subsequent embryonic development, as well as opportunities to investigate primate folliculogenesis by utilizing this 3D culture system. The information may be valuable in identifying optimal conditions for human follicle culture, with the ultimate goal of translating the experimental results and products to patients, thereby facilitating diagnostic and therapeutic approaches for female fertility.

Quantification of ZP1, ZP2 and ZP3 mRNA of marmoset monkey (Callithrix jacchus) oocytes from periantral and antral follicles

In mammals, the oocyte and preimplantation embryo are protected by the zona pellucida (ZP) consisting mainly of ZP glycoproteins, which are responsible for sperm binding, induction of the acrosome reaction and zona pellucida hardening to prevent polyspermia. The ZP proteins become increasingly important as possible predictors for in vitro cultured oocytes competence. As little is known about the stage-dependent expression of ZP1, ZP2 and ZP3 in marmoset monkey (Callithrix jacchus) oocytes, mRNA expression was investigated with real-time RT-PCR. Total-RNA was isolated from three different classes of marmoset oocytes; Class 1 oocytes from periantral follicles (<600 μm, n = 10), Class 2 oocytes from small antral follicles (600-1000 μm, n = 10) and Class 3 oocytes from large antral follicles (>1000 μm, n = 9). Compared with Class 1 oocytes mRNA expression of ZP1, ZP2 and ZP3 in Class 2 oocytes was significantly decreased. In Class 3 oocytes, the transcription of ZP1, ZP2 and ZP3 genes showed also a significant decrease compared with Class 1 oocytes. In this study a differently regulated expression of the ZP genes during late folliculogenesis with an obvious downregulation of ZP1, ZP2 and ZP3 could be demonstrated for the first time in the marmoset monkey.

Current progress in oocyte and embryo cryopreservation by slow freezing and vitrification

Preservation of female genetics is currently done primarily by means of oocyte and embryo cryopreservation. The field has seen much progress during its four-decade history, progress driven predominantly by research in humans, cows, and mice. Two basic cryopreservation techniques rule the field – controlled-rate freezing, the first to be developed, and vitrification, which, in recent years, has gained a foothold. While much progress has been achieved in human medicine, the cattle industry, and in laboratory animals, this is far from being the case for most other mammals and even less so for other vertebrates. The major strides and obstacles in human and other vertebrate oocyte and embryo cryopreservation will be reviewed here.

Current achievements and future research directions in ovarian tissue culture, in vitro follicle development and transplantation: implications for fertility preservation

BACKGROUND Female cancer patients are offered 'banking' of gametes before starting fertility-threatening cancer therapy. Transplants of fresh and frozen ovarian tissue between healthy fertile and infertile women have demonstrated the utility of the tissue banked for restoration of endocrine and fertility function. Additional methods, like follicle culture and isolated follicle transplantation, are in development. METHODS Specialist reproductive medicine scientists and clinicians with complementary expertise in ovarian tissue culture and transplantation presented relevant published literature in their field of expertise and also unpublished promising data for discussion. As the major aims were to identify the current gaps prohibiting advancement, to share technical experience and to orient new research, contributors were allowed to provide their opinioned expert views on future research. RESULTS Normal healthy children have been born in cancer survivors after orthotopic transplantation of their cryopreserved ovarian tissue. Longevity of the graft might be optimized by using new vitrification techniques and by promoting rapid revascularization of the graft. For the in vitro culture of follicles, a successive battery of culture methods including the use of defined media, growth factors and three-dimensional extracellular matrix support might overcome growth arrest of the follicles. Molecular methods and immunoassay can evaluate stage of maturation and guide adequate differentiation. Large animals, including non-human primates, are essential working models. CONCLUSIONS Experiments on ovarian tissue from non-human primate models and from consenting fertile and infertile patients benefit from a multidisciplinary approach. The new discipline of oncofertility requires professionalization, multidisciplinarity and mobilization of funding for basic and translational research.

The current knowledge on radiosensitivity of ovarian follicle development stages

BACKGROUND

The aim of this paper is to review the available information on ovarian radiation sensitivity and the genetic hazard of ionizing radiation in female mammals including humans.

METHODS

The literature present in the author's laboratories (international papers from the 1970s) was complemented by a Medline literature search using the keywords 'ionizing radiation genetic effects', 'oocyte radiosensitivity' and 'oocyte DNA repair' (1990-2008). Further articles were acquired from citations in the research papers and reports.

RESULTS

Animal data show that oocyte radiosensitivity varies widely according to the follicle/oocyte stage and the species. Oocytes near ovulation show the highest susceptibility to radiation induction of mutational events. Congenital anomalies have been observed after exposure to high doses (1-5 Gy), but extrapolation of these data to humans requires caution. In humans, the dose required to induce permanent ovarian failure would vary from 20.3 Gy at birth to 14.3 Gy at 30 years. Most epidemiological studies found little evidence of genetic diseases at the doses at which medical, occupational or accidental exposure occurred.

CONCLUSIONS

The fact that genetic effects were observed in irradiated animals suggests that these could also occur in humans. The probability of such events remains low compared with the 'spontaneous' risks of genetic effects.

The Macaque Ovary, with Special Reference to the Cynomolgus Macaque (Macaca fascicularis)

Concerning functional and morphological aspects, the ovary of the cynomolgus macaque is representative for the conditions in higher primates like humans and is therefore of major relevance in toxicological research. Against this background, a comprehensive overview about the cynomolgus macaque ovary is given from its embryonic appearance, throughout the adolescent and adult development until old age. The overview includes morphologic characteristics, a description of the different cell types, comparisons between the expression of selected receptors, and some details on hormonal effects if considered necessary for understanding the unit of ovarian morphology and function. The close correlation of hormones and morphological characteristics of the ovary and of the other reproductive organs is emphasized by several schematic drawings and images. Special emphasis is also laid on the comparison to the human organism indicating the similarity of both species and hence underlining the importance of the cynomolgus macaque as a model in toxicological research.

Competing Interests: This article was sponsored by Covance Inc. and Schering-Plough. Martina Zöller and Eberhard Buse are employed by Covance Inc. Eric Van Esch is employed by Schering-Plough. No other competing interests were declared.

Meiotic abnormalities in in vitro-matured marmoset monkey (Callithrix jacchus) oocytes: development of a non-human primate model to investigate causal factors

BACKGROUND

Meiotic abnormalities are thought to be a major causal factor of low embryo development rates, for embryos developed from in vitro-matured oocytes. A new non-human primate model, in the common marmoset, is being developed to facilitate investigation of the mechanisms involved.

METHODS

Oocytes were dissected from antral follicles from three size classes. They were allowed to mature in vitro for only 24 h, in order to focus the investigation on the rapidly maturing oocytes. Chromosome spreads were visualized with Giemsa staining, and spindles /chromosomes with fluorescently labelled anti-alpha-tubulin antibody combined with a DNA fluorochrome.

RESULTS

40% of the oocytes had reached metaphase II (MII) after 24 h. Of the MII oocytes selected for karyotyping, readable chromosomal spreads were obtained from 64%. Overall, 63% of these presented a normal haploid chromosome number of 23,X, with all abnormal karyotypes occurring in the oocytes from small follicles. For another group of MII oocytes, where meiotic spindles were visualized, only half of the MII oocytes displayed well-formed spindles and apparently correct chromosomal alignment.

CONCLUSIONS

This work provides the first information on the normal and aneuploid MII meiotic chromosome sets for the marmoset oocyte, and demonstrates a high rate of chromosomal and spindle abnormality among rapidly maturing oocytes from small antral follicles.

In vitro effects of diethylstilbestrol, genistein, 4-tert-butylphenol, and 4-tert-octylphenol on steroidogenic activity of isolated immature rat ovarian follicles

Isolated rat ovarian follicles grow and produce steroid hormones in vitro and so provide a good model for studying the effects of hormonally active compounds on follicular steroidogenesis. We have evaluated the effects of diethylstilbestrol (DES), genistein (GEN) and two alkylphenols, 4-tert-butylphenol (BP) and 4-tert-octylphenol (OP) on the growth, survival, and steroid hormone and cAMP production by isolated 14-day-old rat (Sprague-Dawley) ovarian follicles. During a 5-day culture, FSH was obligatory for follicle growth and increased estradiol and testosterone secretion in a dose-dependent manner. DES (10(-6) M) caused the strongest decline in estradiol and testosterone levels but did not have detectable effects on either cAMP production or aromatase enzyme activity. GEN caused a prominent decrease in cAMP and testosterone levels without significant changes in secreted estradiol. The latter, apparently, was due to a dose-dependent stimulation of aromatase enzyme activity in the presence of genistein. Both BP and OP decreased estradiol and testosterone secretion in a dose-dependent manner while no effect on aromatase activity was observed. OP, unlike BP, decreased forskolin-induced cAMP levels. Xenoestrogens at the used concentrations did not interfere with the growth and survival of the follicles. The results indicate that isolated ovarian follicles representing intact morphological and functional units offer a sensitive model system for elucidating the female-specific reproductive effects of environmental chemicals.

Penile vibratory stimulation in the marmoset monkey: a practical alternative to electro-ejaculation, yielding ejaculates of enhanced quality

The availability of sufficient amounts of spermatozoa of high quality is one of the main limiting factors in reproductive research and development of reproductive technologies in marmoset monkeys (Callithrix jacchus). Penile vibrostimulation (PVS) has been successfully used in semen collection in the squirrel monkey but with poor success rate in the marmoset. We report here on an improved protocol for PVS with a success rate of almost 90%. Ejaculates obtained by PVS were of enhanced quality compared with those obtained by rectal probe electro-ejaculation (RPE). PVS ejaculates contained on average three to fourfold higher numbers of total and motile spermatozoa. Assessment of sperm kinematics using computer-assisted sperm analysis indicated that there are also functional differences between spermatozoa collected by PVS and RPE. Marmoset spermatozoa in samples obtained by RPE swim in a more convoluted manner compared with those obtained by PVS.