OBJECTIVE: We studied the effect of the site of laser zona opening on the complete hatching of mouse blastocysts and the cell numbers of the completely hatched blastocysts. METHODS: Mouse blastocysts were randomly allocated to the inner cell mass (ICM) group (zona opening performed at the site of the ICM, n=125), the trophectoderm (TE) group (zona opening performed opposite to the ICM, n=125) and the control group (no zona opening, n=125). RESULTS: The rate of complete hatching of the blastocysts was not significantly different in the ICM and the TE group (84.8% vs 80.8%, respectively; p=0.402), but was significantly lower in the control group (51.2%, p<0.001). The cell numbers in the completely hatched blastocysts were comparable in the control group, the ICM group, and the TE group (69±19.3, 74±15.7, and 71±16.8, respectively; p=0.680). CONCLUSION: These findings indicate that the site of laser zona opening did not influence the rate of complete hatching of mouse blastocysts or their cell numbers.
Animals ; Blastocyst* ; Cell Count* ; Herpes Zoster* ; Mice* ; Zona Pellucida

In the studies on the hatching mechanisms in mammals, many investigators focused on the embryonic intrinsic factor(s) in in vitro culture, but the uterine environment as the extrinsic factor(s) is thought to play an important role in hatching mechanism. Therefore, to evaluate the effect of uterine environment on the hatching event in vivo, the immature(GV) and ovulated(MII) oocytes, and the late 2-cell embryos of mouse were transferred to pseudopregnant foster mother's uterus during peri-implantation period. So it was verified whether there would happen hatching by only uterine environment independently on embryonic stage. The ultrastructural changes of the zona surface of transferred group were compared with those of in vivo and vitro group by SEM. 36 hrs after transfer, the immature and ovulated oocytes almost degenerated, and the late 2-cell embryos developed to various embryonic stages. However, the embryos which didn't develop to blastula stage did not hatch. The ultrastructural network of ZP in transferred group seemed to be smoothed uniformly, which was different from in vitro group. In conclusion, it is suggested that the uterine environment during peri-implantation period enhances the embryo hatching by provoking the structural change of ZP.
Animals ; Blastula ; Embryonic Structures* ; Herpes Zoster* ; Humans ; Mammals ; Mice* ; Oocytes* ; Research Personnel ; Uterus ; Zona Pellucida*

It is well known that the bona pellucidae of mouse oocytes become 'hardened' when they are allowed to mature in vitro in the absence of serum components. To see if oocytes already undergone meiotic resumption in vivo exhibit similar zona hardening, hardening of ZP of cumulus-enclosed oocytes(CEOs) was examined after culture in vitro since their release from follicles various hours after hCG injection. When CEOs matured in vivo for 3h or longer were subjected to culture in vitro for 14h with BSA alone, zona hardening was significantly reduced compared to those cultured in vitro from the begining of maturation. However, when CEOs matured in vivo for 5h were freed from cumulus cells and then cultured in vitro with BSA alone, little reduction of zona hardening was observed. Preincubation of CEOs for 5h with fetuin, one of the well known inhibitor of in vitro zone hardening, did not prevent bona hardening during its subsequent culture of CEOs for 14h without fetuin. However, when CEOs precultured with both fetuin and PMSG for 5h and then further cultured with BSA alone for 14h, zona hardening was dramatically reduced. Under these conditions, the expansion of cumulus cell was observed. In addition, CEOs cultured with both BSA and dbcAMP to prevent their meiotic resumption showed a significant increase of zona hardening. Whether the observed zona hardening was correlated with the conversion of ZP2 to ZP2f was examined. Zona pellucida, isolated from CEOs matured for 5h in vivo and then further cultured with BSA alone was subjected to SDS-PAGE. Most of ZP2 molecules from these CEOs did not undergo conversion from ZP2 to ZP2f. From these results, it is concluded that CEOs undergone meiotic resumption in vivo do not exhibit bona hardening when they were subsequently cultured in vitro without serum components. It appears that cumulus cells play an important role in this phenomenon.
Animals ; Bucladesine ; Cumulus Cells ; Electrophoresis, Polyacrylamide Gel ; Fetuins ; Herpes Zoster* ; Mice* ; Oocytes* ; Zona Pellucida

OBJECTIVE: The present study was performed to investigate the efficiency of partial laser assisted hatching (p-LAH; lased 1/2 ZP width from ZP edge) on hatching of mouse blastocysts. METHODS: We used non-contact 1.48 micrometer diode laser (MTM, Switzland) to create a precise hole on zona pellucida. 2-cell embryos were collected from the mouse (ICR) oviduct at 48 hours after hCG administration. Collected 2-cell embryos were cultured in the P-1 medium supplemented with 0.4% BSA. For experiments, embryos at 8-cell stage were used after 20~22 hours in culture. After conventional (c-LAH) or partial laser assisted hatching, the embryos were further cultured in P-1 medium supplemented with 0.4% BSA for 3 days. To compare efficiency of complete and partial laser assisted hatching, hatching rate, hatching time and blastocyst diameter and zona pellucida thickness at hatching time were investigated. Embryos were examined every 12 hours. Blastocyst diameter and zona pellucida thickness at hatching time were measured with an ocular micrometer. RESULTS: Hatching rates of p-LAH group (84.2%) was significantly higher than that of control group (39.3%), but there was no difference between the p-LAH (84.2%) and c-LAH (91.2%). p-LAH group was hatched 12 hours earlier than control group, but hatched 12 hours later than c-LAH group. The diameter of blastocyst at hatching time of p-LAH group (113.1+/-6.4 micrometer) was smaller than that of control group (122.2+/-5.0 micrometer), but larger than that of c-LAH group (102.2+/-2.7 micrometer). Zona pellucida thickness at hatching time of p-LAH group (6.4+/-0.9 micrometer) was thicker than that of control group (4.5+/-1.5 micrometer), but thinner than that of c-LAH group (10.0+/-0.8 micrometer). CONCLUSION: These results suggest that p-LAH may maintains the cell arrangement of early embryos to ensure successful development and prevent precocious hatching of blastocyst when compare to c-LAH and conventional (acidic tyrode) AH. Thus, p-LAH may provide a valuable and effective AH technique for human ART program.
Animals ; Blastocyst ; Embryonic Structures* ; Humans ; Lasers, Semiconductor ; Mice* ; Oviducts ; Zona Pellucida

OBJECTIVE: This study aimed to examine the effect of laser-assisted zona thinning (LAZT) at one or four-points on the blastocyst formation and hatching process in mice with respect to female age. METHODS: Eight-cell or morula embryos collected from superovulated C57BL female mice with different ages (6-11 and 28-31 weeks) were treated with LAZT at one-point (LAZT1) or four-points (LAZT4). The zona pellucida was thinned to more than 70% of its initial thickness by making two holes of 15-20 microm. RESULTS: In the young mice, LAZT resulted in a significant increase in early hatching and hatching rates compared to the control group (p<0.05). However, in the old mice, LAZT significantly increased blastocyst formation as well as early hatching and hatching compared to the controls (p<0.05). These effects were more remarkable in LAZT4 than in LAZT1 and in aged mice than in young ones. CONCLUSION: These results show that multi-point LAZT leads to a significant improvement of blastocyst formation and hatching in mice compared to controls.
Animals ; Blastocyst ; Embryonic Structures* ; Female ; Herpes Zoster* ; Humans ; Mice* ; Morula ; Zona Pellucida

OBJECTIVE: Human infertility clinics have been faced the demand for improving clinical results. The purpose of this study was to evaluate the effect of microsurgical removal of damaged blastomeres (DB) in frozen-thawed embryos on the clinical outcomes. METHODS: From January 2003 to May 2004, out of 258 thawing ET cycles were divided into three groups: Group-1 (n=46): Intact cleavaged embryos after thawing. Remained cycles with embryos containing DB were randomly divided into two groups. Group-2 (n=102): Drilling zona pellucida (ZP) of frozen-thawed embryos by acidified Tyrode's solution. Group-3 (n=110): Drilling ZP and removal of DB. Embryos after microsurgical manipulation were transferred into the uterus of patients. RESULTS: Clinical profiles and the mean number of transferred embryos among three groups were not different. Pregnancy and implantation rates were similar in three groups. It were 30.4% and 9.3% in Group-1, 29.4% and 7.8% in Group-2, and 26.4% and 7.6% in group-3, respectively. Miscarriage rate in Group-3 (37.9%) was slightly higher than those in Group-1 and Group-2 (14.3% and 23.3%), but it was not statistically significant. CONCLUSION: Intact cleaving embryos after DB removal showed higher potent of pregnancy and implantation. We could not find any improvement of clinical outcome by removal of DB in frozen-thawed embryos.
Abortion, Spontaneous ; Blastomeres* ; Embryo Transfer* ; Embryonic Structures* ; Female ; Humans ; Infertility ; Pregnancy ; Pregnancy Rate ; Uterus ; Zona Pellucida

Human sperm-egg recognition, adhesion and fusion are key steps in the whole reproductive process. Some abnormalities in human gamete interaction have been shown to be due to defects in the sperm, others attributed to defects in the zona pellucida (ZP) and the egg plasma membrane. This paper reviews the molecular basis and molecular mechanisms of human sperm-egg interaction. More and more advances in the studies of these aspects are shown to be of significant value to the diagnosis and treatment of infertility as well as to the development of assisted reproductive techniques.
Acrosome Reaction ; physiology ; Female ; Humans ; Infertility, Male ; physiopathology ; Male ; Sperm-Ovum Interactions ; physiology ; Zona Pellucida

Zona pellucida (ZP) plays a key role in the recognition, combination and penetration of sperms and oocytes, the prevention of multiple impregnation, the protection of embryos, and so on. The paper reviews the constitution, molecular structure, biological function and application of zona pellucida in male fertilization.
Acrosome Reaction ; physiology ; Animals ; Female ; Fertility ; physiology ; Humans ; Male ; Mice ; Molecular Structure ; Zona Pellucida ; chemistry ; physiology

Assisted hatching (AH), which is known to improve the hatching potential of mammalian embryos, has been used to increase the pregnancy rate in in vitro fertilization cycles. However, the effect of AH on a trypsin-like protease, which is known to be associated with the hatching process, has not been studied. In this study, we evaluate whether the intactness of zona pellucida affects the secretion of a trypsin-like protease from mouse blastocyst. Four- to 8-cell stage mouse embryos were collected at 66- to 68 hr after hCG injection and divided into 3 groups according to the manipulation of zona pellucida. The groups are no treatment (control), drilling of zona pellucida (ZD) and thinning of zona pellucida (ZT). The activity of a trypsin-like protease, blastocyst development and hatching rate were compared among the three groups at 110 and 135 hr after hCG injection, respectively. The protease activity and blastocyst development were not significantly different among control, ZD and ZT groups at 110 and 135 hr after hCG injection, respectively. However, the hatching rate of ZD and ZT groups was significantly higher than that of control group at each time, respectively (p>0.001). Even in the zona pellucida removed embryos, the protease activity did not differ from the control group. In conclusion, the secretion of a trypsin-like protease from mouse blastocyst does not seem to be affected by the intactness of zona pellucida.
Animal ; Blastocyst/secretion ; Blastocyst/enzymology* ; Female ; Fertilization in Vitro/methods ; Gonadotropins, Chorionic/pharmacology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred CBA ; Pregnancy ; Serine Endopeptidases/secretion ; Serine Endopeptidases/metabolism* ; Zona Pellucida/physiology* ; Zona Pellucida/drug effects

OBJECTIVE: To review the outcomes of preimplantation genetic diagnosis (PGD) using zona drilling with acid Tyrode's solution (chemical zona pellucida drilling, chemical ZD) and those of partial zona dissection (PZD). METHODS: Clinical outcomes of seventy-one couples undergoing 85 PGD cycles from January 2005 to December 2010 were included. Blastocyst formation and the hatching rate, clinical pregnancy rate, ongoing pregnancy rate, implantation rate, and fetal gender ratio of the PZD and chemical ZD groups were compared. RESULTS: Application of PZD resulted in a significantly higher rate of clinical pregnancy (40.7% vs. 15.4%, p=0.022), ongoing pregnancy (35.6% vs. 11.5%, p=0.023), and implantation (18.1% vs. 5.7%, p=0.007) compared with chemical ZD. Among non-transferred embryos, the rate of blastocyst formation on day 5 (49.1% vs. 39.5%, p=0.016) and hatching on day 6 (47.2% vs. 26.5%, p<0.001) were also significantly higher in the PZD group. CONCLUSION: The mechanical zona dissection method showed better outcomes than chemical ZD in terms of the blastocyst development and pregnancy rate. In this study, the fact that chemical ZD was conducted in different period from mechanical method should be considered in interpreting the result.
Blastocyst ; Embryonic Structures ; Family Characteristics ; Herpes Zoster ; Isotonic Solutions ; Mandrillus ; Pregnancy ; Pregnancy Rate ; Preimplantation Diagnosis ; Prostaglandins D ; Zona Pellucida