Search Results

You are looking at 51 - 60 of 837 items for

  • Abstract: IVM x
  • Abstract: IVF x
  • Abstract: in vitro fertilization x
  • Abstract: ICSI x
  • Abstract: IUI x
  • Abstract: ART x
  • Abstract: assisted reproductive technology x
  • Abstract: cryopreservation x
  • Abstract: fertility preservation x
  • Abstract: preimplantation genetic diagnosis x
  • Abstract: donor insemination x
  • Abstract: egg donation x
  • All content x
Clear All Modify Search
Free access

D. A. PISTENMA, N. SNAPIR, and H. C. MEL

Summary.

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.

Free access

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.

Free access

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.

Open access

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.

Free access

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.

Free access

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.

Free access

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.

Free access

T Tharasanit, S Colleoni, G Lazzari, B Colenbrander, C Galli, and T A E Stout

Oocyte cryopreservation is a potentially valuable way of preserving the female germ line. However, the developmental competence of cryopreserved oocytes is presently poor. This study investigated whether the morphology of the cumulus complex surrounding an immature equine oocyte and/or the oocyte’s stage of maturation affect its cryopreservability. Compact (Cp) and expanded (Ex) cumulus oocyte complexes (COCs) were vitrified either shortly after recovery (germinal vesicle stage, GV) or after maturation in vitro (IVM); cryoprotectant-treated and -untreated non-frozen oocytes served as controls. In Experiment I, oocytes matured in vitro and then vitrified, or vice versa, were examined for maturation stage and meiotic spindle quality. Cp and Ex COCs vitrified at the GV stage matured at similar rates during subsequent IVM (41 vs 46% MII), but meiotic spindle quality was better for Cp than Ex (63 vs 33% normal spindles). Vitrifying oocytes after IVM resulted in disappointing post-warming spindle quality (32 vs 28% normal for Cp vs Ex). In Experiment II, oocytes from Cp and Ex COCs vitrified at the GV or MII stages were fertilized by intracytoplasmic sperm injection (ICSI) and monitored for cleavage and blastocyst formation. Oocytes vitrified prior to IVM yielded higher cleavage rates (34 and 27% for Cp and Ex COCs) than those vitrified after IVM (16 and 4%). However, only one blastocyst was produced from a sperm-injected vitrified–warmed oocyte (0.4 vs 9.3% and 13% blastocysts for cryoprotectant-exposed and -untreated controls). It is concluded that, when vitrification is the chosen method of cryopreservation, Cp equine COCs at the GV stage offer the best chance of an MII oocyte with a normal spindle and the potential for fertilization; however, developmental competence is still reduced dramatically.

Free access

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.

Free access

Ming-Wen Li, Kristy L Kinchen, Jadine M Vallelunga, Diana L Young, Kaleb D K Wright, Lisa N Gorano, Katherine Wasson, and K C Kent Lloyd

In the present report we studied the safety, efficacy and efficiency of using an infrared laser to facilitate IVF by assessing fertilization, development and birth rates after laser-zona drilling (LZD) in 30 subfertile genetically modified (GM) mouse lines. We determined that LZD increased the fertilization rate four to ten times that of regular IVF, thus facilitating the derivation of 26 of 30 (86.7%) GM mouse lines. Cryopreserved two-cell stage embryos derived by LZD-assisted IVF were recovered and developed to blastocysts in vitro at the same rate as frozen–thawed embryos derived by regular IVF. Surprisingly after surgical transfer to pseudopregnant recipients the birth rate of embryos derived by LZD-assisted IVF was significantly lower than that of embryos derived by regular IVF. However this result could be completely mitigated by the addition of 0.25 M sucrose to the culture medium during LZD which caused the oocyte to shrink in volume relative to the perivitelline space. By increasing the distance from the laser target site on the zona pellucida, we hypothesize that the hyperosmotic effect of sucrose reduced the potential for laser-induced cytotoxic thermal damage to the underlying oocytes. With appropriate preparation and cautious application, our results indicate that LZD-assisted IVF is a safe, efficacious and efficient assisted reproductive technology for deriving mutant mouse lines with male factor infertility and subfertility caused by sperm–zona penetration defects.