Are you Y S Cho?

Claim your profile

Publications (8)25.88 Total impact

  • Y S Cho, M Svelto, G Calamita
    [Show abstract] [Hide abstract]
    ABSTRACT: Spermatogenesis, the maturation of spermatozoa and their concentration and storage in the seminiferous vessels are associated with considerable fluid secretion or absorption in the male reproductive tract. These fluid movements are in total agreement with the presence of multiple aquaporin (AQP) water channel proteins in germ cells and other tissues within the male reproductive tract. A series of functions of prime importance have already been hypothesized for aquaporins in the physiology of male reproduction. Aquaporins could be involved in the early stages of spermatogenesis, in the secretion of tubular liquid and in the concentration and storage of spermatozoa in the epididymis. In the male reproductive tract, alterations in the expression and functionality and/or regulation of aquaporins have already been demonstrated to be at the basis of forms of male infertility. Indeed, rats with reduced reabsorption of seminiferous fluid in the efferent ducts have been shown to be sub-fertile or infertile. Functions have also been suggested in the fertilization process, where aquaporins may play a role in maintaining osmotic homeostasis in gametes during fertilization. Aquaporins have also been suggested to mediate water movement into antral follicles and to be the pathway for transtrophectodermal water movement during cavitation. Aquaporins are the subject of considerable technological interest for cryopreservation used in medically assisted procreation, as they could be the molecular pathway by which water and/or solutes move across the plasma membrane during the process of freezing/thawing gametes and embryos. Indeed, artificial expression ofAQP3 has been showed to improve the survival of mouse oocytes after cryopreservation.
    Cellular and molecular biology 07/2003; 49(4):515-9. · 0.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Spermatogenesis and sperm maturation and storage are accompanied by significant movements of water, and multiple aquaporin transmembrane water channels (AQPs) have been recognized in the male reproductive tract. Nevertheless, the involvement of aquaporins in male reproductive physiology is mostly unknown. Here the expression and localization of AQP8 in rat spermatogenesis is defined and compared to that of AQP7, another aquaporin expressed in male germ cells. AQP8 mRNA was found in testis but not in epididymis, whereas the AQP7 transcript was present in both locations. By immunoblotting, the AQP8 protein was detected as a 25-kDa band and a 32- to 40-kDa diffuse component corresponding to the core and glycosylated protein, respectively. Membrane fractionation revealed AQP8 both in microsomal and plasma membrane-enriched fractions of rat testis while no apparent bands were detected in epididymis. AQP7 appeared as a 23- to 24-kDa band and was found both in testis and epididymis. By immunofluorescence, AQP8 labeling was found intracellularly as well as over the plasma membrane of germ cells throughout spermatogenesis. AQP7 was present in spermatids and spermatozoa and was predominant over the plasma membrane. AQP8 may be involved in the cytoplasmic condensation occurring during differentiation of spermatids into spermatozoa and in the generation of seminiferous tubule fluid.
    Biology of Reproduction 07/2001; 64(6):1660-6. · 3.45 Impact Factor
  • Fertility and Sterility 09/2000; 74(3). · 4.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to compare the effect of the addition of follicular fluid (FF) collected from preovulatory follicles with that of oestrous mare serum (EMS) (acting as the control) to TCM-199 medium on the in-vitro maturation, fertilization and development of equine cumulus-enclosed oocytes. Oocytes (<30 mm in diameter) were obtained from the ovaries of slaughtered mares. After in-vitro maturation in the presence of the two supplements, their fertilization, cleavage and developmental potential were compared after conventional in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) using frozen-thawed spermatozoa. Follicular fluid did not increase the maturation of oocytes to metaphase II stage compared to control. After IVF, there was no difference in fertilization rates between FF-supplemented oocytes and controls (7/87, 8.4% of oocytes showing two pronuclei with FF versus 7/116, 6% with EMS; not significant). However, after ICSI, FF-supplemented oocytes showed significantly increased normal fertilization (32/85, 37.6% of two-pronuclear oocytes) and developmental potential (15/31, 48% cleavage) compared to the control oocytes (7/47, 14.9%, P < 0.01; and 2/48, 4%, P < 0.01, respectively). Overall, ICSI resulted in increased fertilization rates compared to IVF, regardless of the presence or absence of FF (39/132, 29.5% with ICSI versus 14/203, 6.9%). These results suggest that follicular fluid supplementation may improve the maturity of equine cumulus-enclosed oocytes sufficiently for the successful use of ICSI, but not sufficiently for normal sperm-egg interaction occurring during IVF.
    Human Reproduction 12/1997; 12(12):2766-72. · 4.59 Impact Factor
  • Y S Cho, V Traina, P Boyer
    Human Reproduction 06/1997; 12(5):1116-7. · 4.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Conventional IVF as well as several assisted microfertilization techniques have shown limited success in the horse. After recent positive results achieved with intracytoplasmic injection of a single spermatozoon (ICSI) in human IVF, we chose to try the method in the horse. We compared conventional IVF to ICSI by fertilization rates of oocytes with compact and expanded cumuli and by developmental potential of the resulting embryos. Cumulus-oocyte complexes (COCs) were obtained by aspirating the follicular fluid from the ovaries of slaughtered mares. Complexes showing complete cumulus investment, either compact or expanded, were randomly assigned to IVF or ICSI trials and separately cultured for IVM. Frozen-thawed stallion spermatozoa were prepared for IVF with a swim-up procedure conducted in Talp-Hepes with heparin or for ICSI in Earle's balanced salt solution (EBSS) supplemented with human serum albumin (HSA). Oocytes for IVF were partially decumulated by pipetting, whereas those for ICSI were totally denuded with 80 UI/ml hyaluronidase. Oocytes were fixed, stained and examined for signs of fertilization the day after IVF or ICSI. The percentage of normally fertilized oocytes showing 2 pronuclei or cleavage was significantly higher with ICSI than IVF (29.8%, 17/57 vs 8.7%, 9/103 ; P < 0.01). Significantly higher fertilization rates were observed in oocytes retrieved with an expanded cumulus when submitted to ICSI procedure as compared with IVF (52.2%, 12/23 vs 17.1%, 6 35 ; P < 0.01), whereas in oocytes recovered with a compact cumulus, fertilization rates were low (14.7%, 5/34 with ICSI and 4.4%, 3 68 with IVF; NS). Embryonal development did not occur after culture following IVF, as indicated by absence of cleavage in any of the 93 inseminated oocytes. Following ICSI, 7 of 55 injected oocytes cleaved, 5 of which had shown expanded cumuli; of the 5, 2 were at the 16-cell stage and one each at the 8-, 3- and 2-cell stage, respectively. The other 2 fertilized oocytes, originating from compact cumuli, reached 4- and 8- cell stages, respectively. These results indicate that ICSI can be applied successfully to in-vitro matured equine oocytes to increase the fertilization rates. In addition, it seems that in vitro cytoplasmic maturation of oocytes issuing from a compact cumulus may not be complete enough to lead to a successful fertilization and that ICSI may be a tool to evaluate ooplasmic maturation.
    Theriogenology 04/1997; 47(6):1139-56. · 1.85 Impact Factor
  • Theriogenology 12/1996; 47(1):390-390. · 1.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: No oocytes were obtained at ovum retrieval in a 33-year-old patient with secondary tubal infertility, whereas in a previous cycle nine oocytes were obtained under the same ovarian stimulation protocol as used in the studied cycle. Oocyte retrieval failed in spite of the correct administration of human chorionic gonadotrophin (HCG) as demonstrated by serum beta-HCG concentration (58.6 mIU/ml) on day HCG+1. However, it was shown that progesterone failed to rise even after the administration of exogenous HCG as the luteinizing hormone signal. Therefore, when ovum retrieval fails, the serum progesterone as well as beta-HCG concentrations may be useful to help identify the cause of this unusual event.
    Human Reproduction 12/1993; 8(11):1854-5. · 4.59 Impact Factor