Vitrification, an alternative embryo cryopreservation technology, has become one of the greatest achievements of the past 7 years in human and domestic animal assisted reproduction. Benefits of the new approach are the simplicity, cost-efficiency and high overall efficiency. However, several factors, including human mistakes, slow down the propagation of the new approach. This opinion paper summarises the benefits and analyses issues hampering general acceptance of the method. The strong intention of the author is to promote elimination of these obstacles and support application of the vitrification technology.

Fetal exposure to a suboptimal diet in early pregnancy can result in an increased risk of metabolic diseases in the resulting offspring. Our study focussed on the kidney and examined how its composition can be adversely affected in the young adult further exposed to an obesogenic environment and showed a pronounced increase in renal fat accumulation. We therefore demonstrate that ensuring an optimal maternal diet is consumed during early fetal development has the potential to reduce the risk of metabolic complications in the resulting offspring.

Despite the benefits of cryopreservation, successful cryosurvival of porcine embryos has not been achieved. The present study sought to determine the effects of culture with two different energy substrates (glucose and pyruvate–lactate) on the cryotolerance of in vitro-produced porcine embryos. According to our results, the cryotolerance of embryos depends not only on the cryopreservation procedure, but also on the composition of the culture medium, because the apoptotic index after vitrification–warming was lower after culturing embryos with glucose than with pyruvate–lactate.

We investigated the relationship between antioxidant and cytosolic Ca²⁺ levels and oocyte quality and fertilization rate in the granulosa cells of patients undergoing in vitro fertilization. We found that free cytosolic Ca²⁺ and glutathione levels in granulosa cells of infertile patients who achieved fertilization were increased. We concluded that granulosa cells of infertile patients are under oxidative stress and they have no enough antioxidants intake i.e. glutathione.

In all mammalian species studied to date, MUC1, a large glycoprotein, is lost from the endometrial surface during early pregnancy to allow the embryo to implant. This study demonstrated that, unlike other species, MUC1 persists on the endometrium and fetal membranes of the mare throughout pregnancy. The unusually long pre-implantation period of the equine conceptus may, in part, explain this unusual finding.

Twin births are rare in horses because contact between twin conceptuses in utero usually eliminates one by ‘embryo reduction’, as determined previously ultrasonographically. The present morphological study of 33 sets of multiple conceptuses reveals how contact before ‘fixation’ (immobilisation; Day 16) can progress to mutual adhesion and reduction before and after loss of the capsule (Day 21), with the site of adhesion affecting the severity of the effects on the conceptus undergoing elimination.

The Brazilian Canchim beef cattle have been developed by crossing Charolais and zebu (mainly the Nellore breed) cattle. Data from female Canchim cattle were used to obtain estimates of genetic parameters for reproduction and growth traits. Selection for bodyweight at 420 days of age should be carefully conducted because, in Brazil, most of the animals are reared on pasture for their whole life, and larger females could affect producers’ costs.

Passiflora incarnata is marketed in many countries as a phytomedicine for sleep and anxiety disorders. Most phytomedicines lack information regarding the safety of their use during pregnancy and lactation for both mothers and their progeny. To evaluate the reproductive and developmental toxicity of P. incarnata we administered this phytomedicine orally to female rats during gestation and lactation. No toxicity was observed in the dams. Even though the litter developed normally the sexual behaviour of the male progeny was disrupted. Only 3 out of 11 adult male pups exposed to the higher dose of P. incarnata (~10 times the therapeutic dose) were sexually competent, i.e. presented complete sexual behaviour (mount, intromission and ejaculation). This study reinforces that the use of drugs, including natural ones, during gestation and lactation should be cautiously evaluated because long-lasting functional effects in the progeny in the absence of morphological effects may occur.

The sustainability of ex situ elephant populations would be enhanced by the integration of non-sorted and sex-sorted frozen spermatozoa into current artificial insemination (AI) programs. Results of high-quality ejaculates from one Asian elephant indicate that cryopreservation after up to 12 h, but not 24 h, of chilled storage results in a post-thaw sperm population of acceptable quality for AI. Protocol optimisation is therefore required to maximise the fertility potential of spermatozoa undergoing prolonged (>12 h) chilled storage prior to cryopreservation, such as in the case where ejaculates are destined for sex-sorting.

Effective cryopreservation of porcine zygotes could be important for cloning programs. This study aimed to evaluate the survival of intact in vivo-derived zygotes vitrified using the superfine open pulled-straw (SOPS) method, and to investigate whether cryotolerance is increased through lipid polarisation by centrifugation or by a high-osmolality medium. These pre-treatments did not improve embryo vitrification ability. Untreated in vivo-derived porcine zygotes were successfully vitrified using the SOPS method.

It has been known for some time that, despite of their compact chromatin, spermatozoa contain mRNA. It has been suggested that this mRNA could be a candidate marker for the evaluation of sperm quality. In the present study, we confirm the relationship between early embryo development and the abundance of mRNA in spermatozoa to suggest its use as a marker of sperm quality in the pig. These results could help in the development of a new diagnostic method to evaluate sperm quality.

This research compared circulating P4 in heifers and lactating cows supplemented with an intravaginal P4-releasing device, human chorionic gonadotropin (hCG), or both treatments on Day 5 after AI. Without supplementation, heifers had much greater circulating P4 than lactating cows. Although hCG increased circulating P4 following formation of an accessory corpus luteum, both treatments were required to elevated circulating P4 in lactating cows to similar concentrations as observed in heifers.

This work contributes to the knowledge of female reproductive traits in three phyllostomid bats. Adult ovaries from phyllostomid bats were found to contain adult germ cells located in the cortical region that display expression of germline, stem-cell and proliferative markers. These results show possible evidence for the presence of a process of self-renewal of the germline in adult stages.

Leptin is an endocrine signal of nutritional status and body fat-mass that influences reproduction. We investigated if leptin serum and follicular fluid concentrations, in pre-pubertal animals and in horses, different for body adiposity, could have any influence on the ability of equine oocytes to undergo in vitro maturation. Our data show that maturation rate can be related either to adiposity or to puberty and that sport or obese horses represent a model for studying similar human conditions.