Osmotic stress is an important factor that can result in cell damage during cryopreservation. Before ejaculation or collection for cryopreservation, murine spermatozoa are stored in epididymal fluid, a physiologically hyperosmotic environment (∼415 mmol/kg). The objectives of this study were to determine the osmotic tolerance limits of sperm motion parameters of ICR and C57BL/6 mouse spermatozoa collected in isosmotic (290 mmol/kg) and hyperosmotic (415 mmol/kg) media, and the effect of the osmolality of sperm collection media on sperm fertility after cryopreservation. Our results indicate that murine spermatozoa collected in media with different osmolalities (290 and 415 mmol/kg Dulbecco's phosphate buffered saline (DPBS)) appeared to have different osmotic tolerances for the maintenance of sperm motility and other motion parameters in both mouse strains. The hypo- and hyperosmotic treatments decreased motility and affected other motion parameters of spermatozoa collected in 290 mmol/kg DPBS. The extent of the change of motion parameters after treatments corresponded with the levels of osmotic stress. However, for spermatozoa collected in 415 mmol/kg DPBS, exposure to 290 mmol/kg DPBS tended to increase sperm motility and the quality of their motion parameters. The osmolality of sperm collection medium can affect murine sperm fertility. Spermatozoa collected in 415 mmol/kg medium showed higher fertility compared with spermatozoa collected in 290 mmol/kg as assessed by IVF. Results characterizing murine sperm osmotic tolerance collected in media with different osmolalities from different strains and the effect of collection media osmolality on sperm fertility after cryopreservation will be useful in designing cryopreservation protocols.
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- Abstract: IVM x
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Wei Si, Hongsheng Men, James D Benson, and John K Critser
D. A. PISTENMA, N. SNAPIR, and H. C. MEL
The preservation of the motility and fertilizing capacity of fowl spermatozoa was evaluated under low temperature-low concentration conditions in low-ionic-strength glycine-citrate and glycine-phosphate buffers. Solutions of both buffers at 310 mosmol gave less than a 15% decrement from initial motility values after storage for 6 hr at 3° C in concentrations from 8 to 80× 106 spermatozoa/ml. Fertility results with spermatozoa diluted 1:30 in glycine-citrate buffer, stored for 1½ hr at 3° C and re-concentrated by centrifugation, did not differ from control values, using 1:2 dilution in modified Krebs' solution. These experimental media are thus proved capable of maintaining the vital functions of fowl spermatozoa during storage and for certain desired biophysical studies. They may, therefore, be of potential practical value for work in poultry husbandry and genetics.
Candace M Tingen, Sarah E Kiesewetter, Jennifer Jozefik, Cristina Thomas, David Tagler, Lonnie Shea, and Teresa K Woodruff
Innovations in in vitro ovarian follicle culture have revolutionized the field of fertility preservation, but the successful culturing of isolated primary and small secondary follicles remains difficult. Herein, we describe a revised 3D culture system that uses a feeder layer of ovarian stromal cells to support early follicle development. This culture system allows significantly improved primary and early secondary follicle growth and survival. The stromal cells, consisting mostly of thecal cells and ovarian macrophages, recapitulate the in vivo conditions of these small follicles and increase the production of androgens and cytokines missing from stromal cell-free culture conditions. These results demonstrate that small follicles have a stage-specific reliance on the ovarian environment, and that growth and survival can be improved in vitro through a milieu created by pre-pubertal ovarian stromal cell co-culture.
S Meachem, V von Schonfeldt, and S Schlatt
Interest in spermatogonia has grown in recent years as a result of exciting developments in stem cell research in general and the development of new research tools allowing the isolation, culture and transplantation of these cells. This review focuses on the methodological breakthroughs and highlights the recent findings that have substantially increased understanding of spermatogonial physiology. The article provides a comprehensive overview of the hormonal regulation of spermatogonia and presents several new approaches to the use of spermatogonia in basic science and medicine. In the near future these techniques will allow the development of novel routes for the generation of transgenic lifestock, the treatment of infertility, the targeting for male contraception, and an alternative strategy for fertility preservation of oncological patients.
Renjie Wang, Wei Pan, Lei Jin, Yuehan Li, Yudi Geng, Chun Gao, Gang Chen, Hui Wang, Ding Ma, and Shujie Liao
Artificial intelligence (AI) has experienced rapid growth over the past few years, moving from the experimental to the implementation phase in various fields, including medicine. Advances in learning algorithms and theories, the availability of large datasets and improvements in computing power have contributed to breakthroughs in current AI applications. Machine learning (ML), a subset of AI, allows computers to detect patterns from large complex datasets automatically and uses these patterns to make predictions. AI is proving to be increasingly applicable to healthcare, and multiple machine learning techniques have been used to improve the performance of assisted reproductive technology (ART). Despite various challenges, the integration of AI and reproductive medicine is bound to give an essential direction to medical development in the future. In this review, we discuss the basic aspects of AI and machine learning, and we address the applications, potential limitations and challenges of AI. We also highlight the prospects and future directions in the context of reproductive medicine.
Richard M Schultz
The recent surge of interest in oocyte development has been spurred in large part by the increasing implementation of assisted reproductive technologies (ART) to treat human infertility. What is becoming apparent is that ‘egg quality’ is a primary factor in the success of ART (), and yet we know virtually nothing about the molecular signature of a ‘high quality’ oocyte, i.e., an oocyte that is capable of maturing, being fertilized and supporting development to term. We are gaining marked insights, however, into how sperm activate eggs and the changes in gene expression that accompany preimplantation development. Nevertheless, embryo culture is known to effect gene expression (), the long-term consequences of which are only recently being unmasked. This review will briefly highlight these topics that were presented during the Biennial Joint Meeting of the UK Fertility Societies at Warwick University in April 2005.
Yi-Fan Gu, Chang-Fu Lu, Ge Lin, and Guang-Xiu Lu
The cryopreservation of human embryos is thought to induce alteration in the glycoprotein matrix and lead to zona change. However, this assumption has been full of controversies till now. The objective of this study was to evaluate the effect of cryopreservation on zona pellucida of human embryos. Fresh (n=106, from 40 patients) and frozen–thawed embryos (n=123, from 40 patients) were obtained from consenting patients who received conventional IVF and ICSI treatment. The birefringence of zona pellucida in human fresh and frozen–thawed embryos was imaged and quantitatively analyzed using polarized light microscopy before embryo transfer. There was no significant difference in retardance and thickness of the zona pellucida multilaminar structure between the two groups. Pregnancy and implantation rates of transferred fresh and frozen–thawed embryos were also compared. No significant difference was found in the rates of clinical pregnancy (47.5 vs 37.5%) and implantation (24.5 vs 23.2%) between the two groups. This study suggests that there is no significant change in the zona pellucida birefringence of human embryos before and after cryopreservation.
Linda Lefièvre, Kweku Bedu-Addo, Sarah J Conner, Gisela S M Machado-Oliveira, Yongjian Chen, Jackson C Kirkman-Brown, Masoud A Afnan, Stephen J Publicover, W Christopher L Ford, and Christopher L R Barratt
Although sperm dysfunction is the single most common cause of infertility, we have poor methods of diagnosis and surprisingly no effective treatment (excluding assisted reproductive technology). In this review, we challenge the usefulness of a basic semen analysis and argue that a new paradigm is required immediately. We discuss the use of at-home screening to potentially improve the diagnosis of the male and to streamline the management of the sub-fertile couple. Additionally, we outline the recent progress in the field, for example, in proteomics, which will allow the development of new biomarkers of sperm function. This new knowledge will transform our understanding of the spermatozoon as a machine and is likely to lead to non-ART treatments for men with sperm dysfunction.
R John Aitken
There has never been a greater need for scientists trained in reproductive science. Most developed countries are witnessing unprecedented rates of recourse to assisted conception sitting cheek-by-jowl with high rates of induced abortion. This article addresses these two incongruous faces of reproductive healthcare. Every year at least 44 million abortions are performed worldwide, many under unsafe and insanitary conditions that carry a significant risk to the lives of women deprived of safe, effective methods for controlling their fertility. Although birth control is a complex issue involving myriad social and political factors, the technical vacuum in this area is significant. Through no fault of the family planning authorities, there have been no radically new methods of fertility control since the oral contraceptive pill was introduced in 1960 and even this contribution to planned parenthood has its roots in the biochemistry of the 1920s and 1930s. Moreover, the pharmaceutical industry has, by and large, turned its back on fundamental research activities in this area. At present, our major investment in reproductive healthcare involves treating ever-increasing numbers of couples with assisted reproductive technologies (ART). However, these treatments are often delivered without critically considering the underlying causes of this condition or seriously contemplating the long-term consequences of the current enthusiasm for such therapy. Significantly, the clinical factors underpinning the commitment of couples to ART include advanced maternal age and a variety of lifestyle factors, such as smoking and obesity, which are known to compromise the developmental potential of the oocyte and DNA integrity in spermatozoa.
Anna T Grazul-Bilska, Mary Lynn Johnson, Pawel P Borowicz, Jerzy J Bilski, Taylor Cymbaluk, Spencer Norberg, Dale A Redmer, and Lawrence P Reynolds
Utero-placental growth and vascular development are critical for pregnancy establishment that may be altered by various factors including assisted reproductive technologies (ART), nutrition, or others, leading to compromised pregnancy. We hypothesized that placental vascularization and expression of angiogenic factors are altered early in pregnancies after transfer of embryos created using selected ART methods. Pregnancies were achieved through natural mating (NAT), or transfer of embryos from NAT (NAT-ET), or IVF or in vitro activation (IVA). Placental tissues were collected on day 22 of pregnancy. In maternal caruncles (CAR), vascular cell proliferation was less (P<0.05) for IVA than other groups. Compared with NAT, density of blood vessels was less (P<0.05) for IVF and IVA in fetal membranes (FM) and for NAT-ET, IVF, and IVA in CAR. In FM, mRNA expression was decreased (P<0.01–0.08) in NAT-ET, IVF, and IVA compared with NAT for vascular endothelial growth factor (VEGF) and its receptor FLT1, placental growth factor (PGF), neuropilin 1 (NP1) and NP2, angiopoietin 1 (ANGPT1) and ANGPT2, endothelial nitric oxide synthase 3 (NOS3), hypoxia-inducible factor 1A (HIF1A), fibroblast growth factor 2 (FGF2), and its receptor FGFR2. In CAR, mRNA expression was decreased (P<0.01–0.05) in NAT-ET, IVF, and IVA compared with NAT for VEGF, FLT1, PGF, ANGPT1, and TEK. Decreased mRNA expression for 12 of 14 angiogenic factors across FM and CAR in NAT-ET, IVF, and IVA pregnancies was associated with reduced placental vascular development, which would lead to poor placental function and compromised fetal and placental growth and development.