Fertility preservation in men and women: Where are we in 2021? Are we rising to the challenge?

Demand for fertility preservation in women for oncologic, nononcologic, and personal reasons has increased dramatically. Meeting that demand is a major challenge, and we are rising to the challenge. Mature oocyte cryopreservation after ovarian stimulation and ovarian tissue cryopreservation are both methods endorsed by the American Society for Reproductive Medicine (formerly The American Fertility Society), and numerous papers confirmed their efficacy. In girls and women with leukemia or cancers who are at a high risk of ovarian metastasis and who may not be eligible for ovarian tissue transplantation, restoration of fertility can only be achieved by in vitro methods. Male fertility preservation has also become a pressing issue and is extensively reviewed in the present journal issue.

Reproduction in domestic ruminants during the past 50 yr: discovery to application.

The study of reproductive physiology in domestic ruminants has progressed from the whole animal to the molecular level in an amazingly short period of time. The volume of information on this subject is enormous; therefore, we have focused on domestic ruminants, with an emphasis on cattle. To date, artificial insemination (AI) is perhaps the most powerful technique that reproductive physiologists and geneticists have provided the livestock industry for genetic improvement. Early efforts to establish AI as a tool were initiated in Russia around 1899 and since that time major advances in methods of semen collection, evaluation of male fertility, cryopreservation of sperm, sex-sorted semen, and estrous cycle control have occurred. The preceding advances not only led to the widespread use of AI, but also contributed to our fundamental understanding of ovulation control, timing of insemination, gamete biology, and cryopreservation. In regards to anestrus, our understanding of the concept of neuroendocrine control of the pituitary gland and the role of steroid feedback led to the Gonadostat Theory, which proposes that onset of puberty is due to a decrease in the negative feedback of gonadal steroids over time. Subsequent studies in prepuberal and postpartum sheep and cattle established that a short luteal phase frequently precedes the first normal length cycle that is accompanied by estrous expression. This observation led to the common practice of treating prepuberal heifers and anestrous postpartum cows with a short-term progestin treatment (e.g., Controlled Internal Drug Release) to induce normal estrous cycles. In domestic ruminants, fertilization rate is high (85% to 95%); however, significant embryonic mortality before or around the time of maternal recognition of pregnancy (MRP) reduces the pregnancy rate to a single breeding. Significant effort has been directed at determining the time of MRP, the signal for MRP, as well as elucidating the physiological, cellular, and molecular dialogue between the conceptus and uterine environment. Advancements have now led us to the ability to edit the genome to alleviate disease and possibly improve production traits. In summary, major advancements in our understanding of reproductive biology have stemmed from efforts to establish the AI and embryo transfer technique and reduce the negative impact of anestrus and embryonic mortality in domestic ruminants.

History of cryobiology, with special emphasis in evolution of mouse sperm cryopreservation.

Confucius said study the past if you would define the future and a popular statement says that history depends on who writes it. To talk about history it is necessary to find and define a milestone where to start the narration. The intention of this quick review is to take the reader through moments and selected publications; part and pieces of memories showing how the concept of cryopreservation, specifically for mouse sperm, was conceived and sustained as we know it today. Beginning with the development of the microscope (1677) and continuing through the 17th century with the first documented observation by L. Spallanzani describing that sperm could maintain the motility under cold conditions. As J. Sherman suggested, we divide the cryopreservation evolution into two sequences, previous to and after 1949 when Polge, Smith and Parkes discovered the property of glycerol as cryoprotectant. Later, in 1972, D. Whittingham, S. Leibo, and P. Mazur applying a slow freezing process achieved the first embryo freezing (mouse). During that time many theories were scientifically confirmed. Among those, Peter Mazur demonstrated the relation between the speed of freezing and intracellular ice formation, and Stanley Leibo that each cell type has their unique freezing curve. In 1950, after the discovery of the protective aspect of glycerol, sperm from many mammals were frozen, except from the mouse. It was in the early 90's when the mouse sperm freezing becomes important and it was a real challenge for many groups, nevertheless, the technique using skim milk and raffinose modified by Dr Nakagata was the beginning of a different story ….

Advances in cryopreservation: we are not frozen in time.

Life is like riding a bicycle, to keep your balance you must keep moving. -Albert Einstein.

Chapter 1 Historical Background on Gamete and Embryo Cryopreservation.

This chapter describes the development of the science of cryopreservation of gametes and embryos of various species including human. It attempts to record in brief the main contributions of workers in their attempts to cryopreserve gametes and embryos. The initial difficulties faced and subsequent developments and triumphs leading to present-day state of the art are given in a concise manner. The main players and their contributions are mentioned and the authors' aim is to do justice to them. This work also attempts to ensure that credit is correctly attributed for significant advances in gamete and embryo cryopreservation. In general this chapter has tried to describe the historical development of the science of cryopreservation of gametes and embryos as accurately as possible without bias or partiality.

[The Cryopre-servation: history and the ethical issue of storing embryos]. / Kryokonzervace: historie a etická problematika skladování embryí.

This review article deals with the technique which is called cryopreservation. Text describes the principle of this method, history and ethical problems in assisted reproduction.

Some personal and historical notes on the utility of "deep-etch" electron microscopy for making cell structure/function correlations.

This brief essay talks up the advantages of metal replicas for electron microscopy and explains why they are still the best way to image frozen cells in the electron microscope. Then it explains our approach to freezing, namely the Van Harreveld trick of "slamming" living cells onto a supercold block of metal sprayed with liquid helium at -269ºC, and further talks up this slamming over the alternative of high-pressure freezing, which is much trickier but enjoys greater favor at the moment. This leads me to bemoan the fact that there are not more young investigators today who want to get their hands on electron microscopes and use our approach to get the most "true to life" views of cells out of them with a minimum of hassle. Finally, it ends with a few perspectives on my own career and concludes that, personally, I'm permanently stuck with the view of the "founding fathers" that cell ultrastructure will ultimately display and explain all of cell function, or as Palade said in his Nobel lecture,electron micrographs are "irresistible and half transparent … their meaning buried under only a few years of work," and "reasonable working hypotheses are already suggested by the ultrastructural organization itself."

Cryopreservation of oocytes and embryos.

Two hundred years have passed since the first description of supercooled water by Gey-Lussac to the recently high survival rates of embryo and oocytes after vitrification. This review discusses important milestones that have made vitrification the method of choice for oocytes and embryos cryopreservation. We will go through the first cells ever to survive low temperature exposure in the beginning of the last century, the finding of glycerol in the late 1940s and the first mouse and bovine embryos freezing in the 1970s. During the 1980s, embryo vitrification began and the time since is a tribute to the development of oocytes vitrification. Standardization and an automatic vitrification procedure are currently under development. The next evolutionary step in oocyte and embryo cryopreservation will be preserving them in the dry state at room temperature, allowing home storage for future use a reality.

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.

Biopreservation of hepatocytes: current concepts on hypothermic preservation, cryopreservation, and vitrification.

Isolated liver cells (primarily isolated hepatocytes) have found important applications in science and medicine over the past 40 years in a wide range of areas, including physiological studies, investigations on liver metabolism, organ preservation and drug de-toxification, experimental and clinical transplantation. An integral component of many of these works is the need to store the isolated cells, either for short or long-term periods. This review covers the biopreservation of liver cells, with a focus on the history of liver cell biopreservation, the application of hypothermia for short-term storage, standard cryopreservation methods for isolated hepatocytes, the biopreservation of other types of liver cells, and recent developments such as vitrification of hepatocytes. By understanding the basis for the different approaches, it will be possible to select the best options for liver cell biopreservation in different applications, and identify ways to improve preservation protocols for the future.

Topografia do cone medular da irara (Eira barbara) e sua relevância em anestesias epidurais / Topography of the conus medullari in tayra (Eira barbara) and their relevance in epidural anesthesia

Encontrada principalmente na América do Sul, a irara é um carnívoro pertencente à família Mustelidae, a qual pouco se tem informações sobre sua morfologia de forma geral. Diante disso, objetivou-se conhecer melhor parte do sistema nervoso desta espécie, mais precisamente a topografia do cone medular, a fim de subsidiar intervenções anestésicas peridurais nesta, uma vez que a clínica de animais selvagens vem crescendo a cada dia. Foram estudados três exemplares machos, adultos, provenientes da área de Mina Bauxita, Paragominas, doados ao Laboratório de Pesquisa Morfológica Animal (LaPMA), Universidade Federal Rural da Amazônia (UFRA), Belém, os quais foram radiografados e dissecados ao nível lombossacral, seguido de exposição do cone medular. Este, por sua vez, situou-se entre L4-L6 possuindo comprimento médio de 4,31cm, o que nos levou a sugerir a região sacrococcígea como ponde ideal para prática de anestesias epidurais nesta espécie.

Mainly found in South America, tayra is a carnivore belonging to the Mustelidae family, of which is little information regarding its morphology in general. The study aimed to characterize the topography of the medullar cone in order to subsidize epidural anesthetic interventions, since the clinics of wild animals is growing each day. We studied three adult male tayras from the Bauxite Mine area of Paragominas, donated to the Research Laboratory of Animal Morphology, Federal Rural University of Amazonia, Belém. They were x-rayed and dissected at the lumbosacral level to expose the medullar cone, which was found between L4-L6 with an average length of 4.31cm. This led us to suggest the sacrococcygeal region as ideal site for practice of epidural anesthesia in this species.

Sixty years of blood transfusion: a memoir.

Paul Schmidt was born in 1925 into the Greatest Generation. Events during military service decided him on the study of medicine. Early research training in red cell preservation that continued during his medical studies opened a 20-year career at the National Institutes of Health (NIH). Beginning in 1954 at the Blood Bank of the NIH Clinical Center, he had exposure to the pioneers who had translated transfusion's wartime beginnings into civilian applications. Work inside the unique NIH clinical research atmosphere together with many of his students provided a fertile field for the growth of what has become transfusion medicine. Topics described range from early studies on platelets and on hepatitis to the background in Washington health politics leading to the National Blood Policy. National and global organizational activity and a second career in community blood service added to his 65 years of experience. The story as transfusion history is presented as a template for future progress.

History of oocyte cryopreservation.

The potential advantages of being able to cryopreserve oocytes have been apparent for many decades. Technical difficulties associated with the unique properties of the mammalian oocyte initially retarded rapid development in this area but recent advances have overcome many of the problems. A stage has now been reached where oocyte cryopreservation can be considered an important component of human assisted reproductive technology. The potential advantages of being able to cryopreserve oocytes have been apparent for many decades. Technical difficulties associated with the unique properties of the mammalian oocyte initially retarded rapid development in this area but recent advances have overcome many of the problems. A stage has now been reached where oocyte cryopreservation can be considered an important component of human assisted reproductive technology.

Cryopreservation of ovarian tissue for a decade in Denmark: a view of the technique.

This paper presents the Danish 10-year experience (1999-2009) with cryopreservation (n=386) and autotransplantation of ovarian tissue (n=18). Before applying the technique to humans, the method was thoroughly tested and validated. The cryoprotectant solution was chosen after histological evaluation of mouse and human ovarian tissue after freezing with four different combinations of cryoprotectants. Viability was confirmed by transplantation of frozen-thawed human ovarian tissue (n=49) to oophorectomized Nude mice. Viability after transport of fresh tissue 4-5h prior to freezing had previously been validated. Overnight transport of fresh ovarian tissue prior to cryopreservation was evaluated when human ovarian tissue was kept on ice for 20h and then cryopreserved. The thawed ovarian tissue was transplanted to an oophorectomized Nude mouse and histology confirmed viability. In Denmark 12 women have received a total of 18 autotransplantations of ovarian tissue. All women resumed ovarian function and three healthy babies were born to two women. In both women, the tissue was transported on ice for 4-5h prior to cryopreservation. Ovarian tissue cryopreservation is an important method for fertility preservation; however, before applying the method clinically, each laboratory should perform thorough validation of their technique.