Embryo competence and cryosurvival: Molecular and cellular features

Global cattle genetic market is experiencing a change of strategy, large genetic companies, traditionally recognized in the artificial insemination field, have also begun to operate in the embryo market. Consequently, the demand for in vitro produced (IVP) embryos has grown. However, the overall efficiency of the biotechnology process remains low. Additionally, the lack of homogeneity of post-cryopreservation survival results of IVP embryos still impairing a massive dissemination of this biotechnology in the field. A great challenge for in vitro production labs is to increase the amount of embryos produced with exceptional quality after each round of in vitro fertilization. Herein, we discuss the molecular and cellular features associated with the competence and cryosurvival of IVP embryos. First, morphofunctional, cellular and molecular competence of the embryos were addressed and a relationship between embryo developmental ability and quality were established with cryosurvival and pregnancy success. Additionally, determinant factors of embryo competence and cryosurvival were discussed including the following effects: genotype, oocyte quality and follicular microenvironment, in vitro production conditions, and lipids and other determining molecules. Finally, embryo cryopreservation aspects were addressed and an embryofocused approach to improve cryosurvival was presented.(AU)

Colheita transcervical de embriões em ovelhas e cabras / Transcervical embryo collection in ewes and does

A biotécnica de múltipla ovulação e transferência de embriões (MOTE) em pequenos ruminantes tem aplicações que se estendem da pesquisa básica à aplicada. Porém, ainda existem etapas no processo da biotécnica que reduzem sua eficiência e restringem sua utilização, a exemplo da necessidade de procedimentos cirúrgicos. Em caprinos, já é possível realizar a MOTE sem nenhuma intervenção cirúrgica e com resultados satisfatórios. Todavia, em ovinos, as particularidades anatômicas da cérvix dificultam sua transposição, fazendo com que etapas cirúrgicas ainda sejam necessárias. Com foco nessa limitação, tem-se estudado e descrito técnicas para a dilatação cervical e métodos para triagem de doadoras de embrião com maior facilidade para transposição cervical. Assim, a colheita não cirúrgica, principalmente na espécie ovina, vem se tornando uma realidade exequível em condições de campo e pesquisa.(AU)

In small ruminants, the multiple ovulation and embryo transfer (MOET) has applications in basic and applied research. However, there are still drawbacks in this biotechnology hampering its applicability and efficiency, as the need of surgical intervention. In goats, it is possible to perform MOET without any surgical procedure and with satisfactory results. Although, in sheep, the anatomical features of the cervix make transcervical transposition challenging, leading to a wider use of surgical steps in this specie. In the attempt to overcome these limitations, techniques for cervical dilation and methods for screening donors with cervices that can be easily transposed have been studied and described. Therefore, the nonsurgical embryo collection, mainly in the ovine species, has become feasible under field and research conditions.(AU)

Embryo competence and cryosurvival: Molecular and cellular features

Global cattle genetic market is experiencing a change of strategy, large genetic companies, traditionally recognized in the artificial insemination field, have also begun to operate in the embryo market. Consequently, the demand for in vitro produced (IVP) embryos has grown. However, the overall efficiency of the biotechnology process remains low. Additionally, the lack of homogeneity of post-cryopreservation survival results of IVP embryos still impairing a massive dissemination of this biotechnology in the field. A great challenge for in vitro production labs is to increase the amount of embryos produced with exceptional quality after each round of in vitro fertilization. Herein, we discuss the molecular and cellular features associated with the competence and cryosurvival of IVP embryos. First, morphofunctional, cellular and molecular competence of the embryos were addressed and a relationship between embryo developmental ability and quality were established with cryosurvival and pregnancy success. Additionally, determinant factors of embryo competence and cryosurvival were discussed including the following effects: genotype, oocyte quality and follicular microenvironment, in vitro production conditions, and lipids and other determining molecules. Finally, embryo cryopreservation aspects were addressed and an embryofocused approach to improve cryosurvival was presented.

Colheita transcervical de embriões em ovelhas e cabras / Transcervical embryo collection in ewes and does

A biotécnica de múltipla ovulação e transferência de embriões (MOTE) em pequenos ruminantes tem aplicações que se estendem da pesquisa básica à aplicada. Porém, ainda existem etapas no processo da biotécnica que reduzem sua eficiência e restringem sua utilização, a exemplo da necessidade de procedimentos cirúrgicos. Em caprinos, já é possível realizar a MOTE sem nenhuma intervenção cirúrgica e com resultados satisfatórios. Todavia, em ovinos, as particularidades anatômicas da cérvix dificultam sua transposição, fazendo com que etapas cirúrgicas ainda sejam necessárias. Com foco nessa limitação, tem-se estudado e descrito técnicas para a dilatação cervical e métodos para triagem de doadoras de embrião com maior facilidade para transposição cervical. Assim, a colheita não cirúrgica, principalmente na espécie ovina, vem se tornando uma realidade exequível em condições de campo e pesquisa.

In small ruminants, the multiple ovulation and embryo transfer (MOET) has applications in basic and applied research. However, there are still drawbacks in this biotechnology hampering its applicability and efficiency, as the need of surgical intervention. In goats, it is possible to perform MOET without any surgical procedure and with satisfactory results. Although, in sheep, the anatomical features of the cervix make transcervical transposition challenging, leading to a wider use of surgical steps in this specie. In the attempt to overcome these limitations, techniques for cervical dilation and methods for screening donors with cervices that can be easily transposed have been studied and described. Therefore, the nonsurgical embryo collection, mainly in the ovine species, has become feasible under field and research conditions.

Oocyte related factors impacting on embryo quality: relevance for in vitro embryo production

The outcome of pregnancy is closely linked to early events that occur during the onset of embryogenesis. The first stages in embryonic development are mainly governed by the storage of maternal factors present in the oocyte at the time of fertilisation. In this review, we outline the different classes of oocyte transcripts that may be involved in activation of the embryonic genome as well as those associated with epigenetic reprogramming, imprinting maintenance or the control of transposon mobilisation during preimplantation development. We also report the influence of cumulus-oocyte crosstalk during the maturation process on the oocyte transcriptome and how in vitro procedures can affect these interactions.

Oocyte related factors impacting on embryo quality: relevance for in vitro embryo production

The outcome of pregnancy is closely linked to early events that occur during the onset of embryogenesis. The first stages in embryonic development are mainly governed by the storage of maternal factors present in the oocyte at the time of fertilisation. In this review, we outline the different classes of oocyte transcripts that may be involved in activation of the embryonic genome as well as those associated with epigenetic reprogramming, imprinting maintenance or the control of transposon mobilisation during preimplantation development. We also report the influence of cumulus-oocyte crosstalk during the maturation process on the oocyte transcriptome and how in vitro procedures can affect these interactions.(AU)

Does maternal size, nutrition and metabolic status affect offspring production traits in domestic species?

The Developmental Origins of health and Disease state that environmental conditions during pregnancy affect long term outcomes in offspring. In the present paper, effects of maternal size and breed as well as maternal nutrition on offspring size, growth and production traits are described. Although birthweight is mostly not affected, metabolic perturbations are often observed in adult offspring. In animal production, however, the relation between developmental conditions and long-term offspring outcome may remain unnoticed. Nevertheless, improving dams' health and nutrition before and during pregnancy may help improving production traits in domestic animals.

Does maternal size, nutrition and metabolic status affect offspring production traits in domestic species?

The Developmental Origins of health and Disease state that environmental conditions during pregnancy affect long term outcomes in offspring. In the present paper, effects of maternal size and breed as well as maternal nutrition on offspring size, growth and production traits are described. Although birthweight is mostly not affected, metabolic perturbations are often observed in adult offspring. In animal production, however, the relation between developmental conditions and long-term offspring outcome may remain unnoticed. Nevertheless, improving dams' health and nutrition before and during pregnancy may help improving production traits in domestic animals.(AU)