Looking back at five decades of embryo technology in practice.

This paper covers developments from International Embryo Technology Society (IETS) meetings over the past 50years. The IETS was officially 'born' at a meeting in Denver, Colorado on Sunday 26 May 1974. There have been 51 IETS meetings (the first was in May 1974), and the first conference at which papers were presented was in 1975. The name of the IETS was changed from International Embryo Transfer Society to International Embryo Technology Society in 2016. The annual IETS conferences are held once a year in January. Embryo technology advanced from the laborious and slow techniques of surgical recovery and transfer of bovine embryos to non-surgical recovery and transfer in many species. Cryopreservation of embryos was initially a slow process that met with only moderate technical success before the development of technology that resulted in high embryo survival rates. The polymerase chain reaction was used to determine the sex of embryos following laminar flow cytology, which came into use to separate X- and Y-bearing spermatozoa. IVF has grown to become widely used, and several factors make it more useful than superovulation and embryo recovery/transfer. Perhaps the most important tool of all was the system that allowed the genetic 'mapping' of the genomic sequence of Bos taurus cattle. Charting key DNA differences by scientists, 'haplotypes' are now used routinely to identify animals with desirable traits of economic importance, discover new genetic disorders, and track carrier status of genotyped animals. Future technology is discussed.

Forty years of embryo transfer in cattle: a review focusing on the journal Theriogenology, the growth of the industry in North America, and personal reminisces.

After the first successful transfer of mammalian embryos in 1890, it was approximately 60 years before significant progress was reported in the basic technology of embryo transfer (ET) in cattle. Starting in the early 1970s, technology had progressed sufficiently to support the founding of commercial ET programs in several countries. Today, well-established and reliable techniques involving superovulation, embryo recovery and transfer, cryopreservation, and IVF are utilized worldwide in hundreds, if not thousands, of commercial businesses located in many countries. The mean number of embryos produced via superovulation has changed little in 40 years, but there have been improvements in synchrony and hormonal protocols. Cryopreservation of in vivo-derived embryos is a reliable procedure, but improvements are needed for biopsied and in vitro-derived embryos. High pregnancy rates are achieved when good quality embryos are transferred into suitable recipients and low pregnancy rates are often owing to problems in recipient management and not technology per se. In the future, unanticipated disease outbreaks and the ever-changing economics of cattle and milk prices will continue to influence the ET industry. The issue of abnormal pregnancies involving in vitro embryos has not been satisfactorily resolved and the involvement of abnormal epigenetics associate with this technology merits continued research. Last, genomic testing of bovine embryos is likely to be available in the foreseeable future. This may markedly decrease the number of embryos that are actually transferred and stimulate the evolution of more sophisticated ET businesses.

Evolution of dental school clinics as patient care delivery centers.

Dental school clinics, originally envisioned as closely similar to private practice, evolved instead as teaching clinics. In the former, graduate and licensed dentists perform the treatment while undergraduate dental students are assigned treatment within their capabilities. In the latter, dental students provide the treatment under faculty supervision. It is generally recognized that the care provided by the teaching clinics is inefficient. However, in the last quarter of the twentieth century, dental school clinics began to pay much more attention to how treatment is rendered. The comprehensive care movement and quality assurance systems are leading towards more efficient patient-centered care. Case studies at the University of Maryland, Columbia University, and University of Louisville describe activities to make their clinic programs more efficient and patient-friendly. This article explores whether the potential exists for faculty to take a direct patient care delivery role in dental clinics in order for those clinics to become efficient patient care delivery systems as originally envisioned in the early part of the twentieth century.

Evolution of dental school clinics as patient care delivery centers.

Dental school clinics, originally envisioned as closely similar to private practice, evolved instead as teaching clinics. In the former, graduate and licensed dentists perform the treatment while undergraduate dental students are assigned treatment within their capabilities. In the latter, dental students provide the treatment under faculty supervision. It is generally recognized that the care provided by the teaching clinics is inefficient. However, in the last quarter of the twentieth century, dental school clinics began to pay much more attention to how treatment is rendered. The comprehensive care movement and quality assurance systems are leading towards more efficient patient-centered care. Case studies at the University of Maryland, Columbia University, and University of Louisville describe activities to make their clinic programs more efficient and patient-friendly. This article explores whether the potential exists for faculty to take a direct patient care delivery role in dental clinics in order for those clinics to become efficient patient care delivery systems as originally envisioned in the early part of the twentieth century.

The current status and future of commercial embryo transfer in cattle.

A commercially viable cattle embryo transfer (ET) industry was established in North America during the early 1970s, approximately 80 years after the first successful embryo transfer was reported in a mammal. Initially, techniques for recovering and transferring cattle embryos were exclusively surgical. However, by the late 1970s, most embryos were recovered and transferred nonsurgically. Successful cryopreservation of embryos was widespread by the early 1980s, followed by the introduction of embryo splitting, in vitro procedures, direct transfer of frozen embryos and sexing of embryos. The wide spread adoption of ethylene glycol as a cryoprotectant has simplified the thaw-transfer procedures for frozen embryos. The number of embryos recovered annually has not grown appreciably over the last 10 years in North America and Europe; however, there has been significant growth of commercial ET in South America. Within North America, ET activity has been relatively constant in Holstein cattle, whereas there has been a large ET increase in the Angus breed and a concomitant ET decrease in some other beef breeds. Although a number of new technologies have been adopted within the ET industry in the last decade, the basic procedure of superovulation of donor cattle has undergone little improvement over the last 20 years. The export-import of frozen cattle embryos has become a well-established industry, governed by specific health regulations. The international movement of embryos is subject to sudden and dramatic disturbances, as exemplified by the 2001 outbreak of foot and mouth disease in Great Britain. It is probable that there will be an increased influence of animal rights issues on the ET industry in the future. Several companies in North America are currently commercially producing cloned cattle. The sexing of bovine semen with the use of flow cytometry is extremely accurate and moderate pregnancy rates in heifers have been achieved in field trials, but sexed semen currently is available in only a few countries and on an extremely limited basis. As of yet, all programs involving the production of transgenic cattle are experimental in nature.

Use of G1.2/G2.2 media for commercial bovine embryo culture: equivalent development and pregnancy rates compared to co-culture.

The expanded application of commercial bovine IVM, IVF, and IVC systems is dependent on the ability to produce embryos in culture that are capable of producing normal pregnancies. Because serum containing culture systems can induce neonatal and fetal problems there exists a definite need for a serum-free culture system that produces viable blastocysts. This study demonstrated that the physiological sequential media system G1.2/G2.2 could produce bovine blastocysts at rates equivalent to co-culture. Additionally, these blastocysts had equivalent or increased cell numbers and inner cell mass development. Blastocysts produced in the G1.2/G2.2 culture system produced pregnancies following both fresh transfer and cryopreservation at equivalent rates to co-culture. Finally, this study demonstrated that the media system G1.2/G2.2 could be used in a commercial OPU transfer program without any loss in the numbers of blastocysts produced or the numbers of pregnancies resulting following transfer from either fresh or cryopreserved blastocysts.

Cryo-survival and development of bovine blastocysts are enhanced by culture with recombinant albumin and hyaluronan.

Recombinant albumin can be used to supplement culture medium for the maturation and fertilization of bovine oocytes and subsequent embryo development to the blastocyst stage. Recombinant albumin was able to support blastocyst development at rates equivalent to that of bovine serum albumin (BSA) supplemented media. Supplementation of media containing recombinant albumin and citrate stimulated blastocyst expansion. Culture with recombinant albumin and citrate significantly increased the ability of the resultant blastocysts to re-expand and hatch following cryopreservation. The further addition of the glycosaminoglycan hyaluronan to the culture medium containing either BSA or recombinant albumin also increased the ability of blastocysts to survive cryopreservation. Inclusion of recombinant albumin and hyaluronan in culture media facilitates the development of physiological defined culture conditions. For bovine embryos this has implications for both research and commercial applications where defined reproducible conditions are desirable.