Optimisation of the bovine whole in vitro embryo system as a sentinel for toxicity screening: a cadmium challenge.

Developmental toxicity testing could greatly benefit from the availability of an in vitro alternative model based on the use of animal embryos that have better human-like physiology than the currently-used alternative models. These current models are insufficient, as extrapolation of the results can be challenging. Therefore, an in vitro bovine embryo culture system was used to expose individual morulae to test substances, and to study developmental characteristics up to the blastocyst stage.

Bovine in vitro reproduction models can contribute to the development of (female) fertility preservation strategies.

Recent increases in the number of successful cancer treatments have stimulated interest in fertility preservation strategies in women of reproductive age and in prepubertal girls. However, research on the application of such programs under clinical conditions suffers from the scarce availability of human tissue for research purposes and from concurrent relevant ethical issues. To partly address this problem, this review focuses on the possibilities of ruminant in vitro models providing additional insights into several aspects of fertility preservation, ranging from preantral follicle collection to oocyte and follicle cryopreservation, to noninvasive quality assessment, and to follicle culture.

Nutrition and maternal metabolic health in relation to oocyte and embryo quality: critical views on what we learned from the dairy cow model.

Although fragmented and sometimes inconsistent, the proof of a vital link between the importance of the physiological status of the mother and her subsequent reproductive success is building up. High-yielding dairy cows are suffering from a substantial decline in fertility outcome over past decades. For many years, this decrease in reproductive output has correctly been considered multifactorial, with factors including farm management, feed ratios, breed and genetics and, last, but not least, ever-rising milk production.

The effect of human follicular fluid on bovine oocyte developmental competence and embryo quality.

In this study, the hypothesis that embryo development during routine IVF procedures is determined by the pre-ovulatory follicular fluid composition was tested. Follicular fluid from women with obesity ('obese') and a 'positive' or 'negative' IVF outcome was added during the in-vitro maturation of bovine oocytes. 'Negative' and 'obese' follicular fluid reduced bovine embryo development, compared with laboratory control embryo development (P < 0.

Elevated non-esterified fatty acid concentrations during in vitro murine follicle growth alter follicular physiology and reduce oocyte developmental competence.

Objective: To study how long-term elevated non-esterified fatty acid (NEFA) concentrations, typical in metabolic disorders such as obesity or type 2 diabetes, affect murine follicular development, follicle quality, and subsequent oocyte developmental competence in vitro.

Design: Experimental study.

Setting: In vitro culture setting.

Analysis and characterisation of bovine oocyte and embryo biomarkers by matrix-assisted desorption ionisation mass spectrometry imaging.

In the field of 'single cell analysis', many classical strategies like immunofluorescence and electron microscopy are the primary techniques of choice. However, these methodologies are time consuming and do not permit direct identification of specific molecular classes, such as lipids. In the present study, a novel mass spectrometry-based analytical approach was applied to bovine oocytes and embryos.

Reduced oocyte and embryo quality in response to elevated non-esterified fatty acid concentrations: a possible pathway to subfertility?

Reproductive performance is increasingly considered as a 'barometer' of general well-being of the mother. A normal maternal 'metabolic health' status is essential to safeguard successful ovulation, conception and further embryo development. When alterations in serum metabolites are reflected in the oocyte and embryonic micro-environment, these metabolic changes can affect follicle health, oocyte development and even subsequent embryo physiology.

Monitoring preantral follicle survival and growth in bovine ovarian biopsies by repeated use of neutral red and cultured in vitro under low and high oxygen tension.

The development and optimization of preantral follicle culture methods are crucial in fertility preservation strategies. As preantral follicle dynamics are usually assessed by various invasive techniques, the need for alternative noninvasive evaluation tools exists. Recently, neutral red (NR) was put forward to visualize preantral follicles in situ within ovarian cortical fragments.

Fatty acid composition of the follicular fluid of normal weight, overweight and obese women undergoing assisted reproductive treatment: a descriptive cross-sectional study.

Background: It has been well documented that the maturing oocyte is very vulnerable to changes in its micro-environment, the follicular fluid (FF). Recent research has focused on different components within this FF, like hormones, growth factors and metabolites, and how their concentrations are altered by diet and the metabolic health of the mother. It has been proposed that fatty acids (FAs) are potential factors that influence oocyte maturation and subsequent embryo development.

Endocrine-disrupting chemicals in human follicular fluid impair in vitro oocyte developmental competence.

Background: Increased global industrial activity has exposed humans to a wide variety of chemical substances some of which, called 'endocrine-disrupting chemicals' (EDCs) or 'endocrine disruptors', can disrupt the endocrine system in the body. The ovarian follicle is a very fragile micro-environment where interactions between hormones, growth factors, the oocyte and its surrounding somatic cells are essential to generate a fully competent oocyte. In vitro experiments suggest that EDCs can disturb this finely tuned balance, but very scarse in vivo data are available to confirm this assumption.

Elevated non-esterified fatty acid concentrations during bovine oocyte maturation compromise early embryo physiology.

Elevated concentrations of serum non-esterified fatty acids (NEFA), associated with maternal disorders such as obesity and type II diabetes, alter the ovarian follicular micro-environment and have been associated with subfertility arising from reduced oocyte developmental competence. We have asked whether elevated NEFA concentrations during oocyte maturation affect the development and physiology of zygotes formed from such oocytes, using the cow as a model. The zygotes were grown to blastocysts, which were evaluated for their quality in terms of cell number, apoptosis, expression of key genes, amino acid turnover and oxidative metabolism.

Occurrence of endocrine disrupting compounds in tissues and body fluids of Belgian dairy cows and its implications for the use of the cow as a model to study endocrine disruption.

The reproductive performance of high producing dairy cows has dropped severely throughout the last decades. It has already been suggested that the presence of endocrine disrupting compounds (EDCs) in the environment could be one of the reasons for this declining fertility. Reliable data concerning tissue and body fluid concentrations of these chemicals are thus crucial, but currently only scarcely available.

Xenotransplantation by injection of a suspension of isolated preantral ovarian follicles and stroma cells under the kidney capsule of nude mice.

Objective: To develop and test a novel approach to xenotransplantation of isolated preantral follicles underneath the kidney capsule of immunodeficient mice.

Design: Prospective experimental animal study.

Setting: Academic research unit.

Follicle survival and growth to antral stages in short-term murine ovarian cortical transplants after Cryologic solid surface vitrification or slow-rate freezing.

This study was designed to asses murine preantral follicle survival and growth, after cryopreservation of ovarian tissue by two different methodologies, solid-surface vitrification by the Cryologic vitrification method (CVM) and slow-rate freezing (SRF). Cryotreated tissue was stored in liquid nitrogen for 24h, and upon warming follicle viability was assessed by live/dead fluorescent probes, and by 7-day autotransplantation of both cryotreated tissue types to the left and right kidney capsule of the donor animals (n=16). The live/dead assay immediately upon tissue warming did not allow a distinction to be made in terms of follicle viability between the CVM and SRF cryoprocedure.

Development and practical applications of a method for repeated transvaginal, ultrasound-guided biopsy collection of the bovine ovary.

In response to the increasing research into primordial and preantral follicular dynamics, a device for transvaginal, ultrasound-guided biopsy collection of the bovine ovary was developed and tested. The new device is based upon a commercially available Ovum Pick-up instrument and consists of a modified needle guidance system, which has been equipped with a trocar needle and caries a 60 cm long true-cut biopsy needle. Biopsies are captured in a 20mm long and 2mm wide specimen notch.