1 Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715 and 2 California National Primate Research Center, Davis, CA, USA
3 To whom correspondence should be addressed at: Wisconsin National Primate Research Center, 1223 Capitol Court, Madison, WI 53715, USA. e-mail: schramm{at}primate.wisc.edu
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: fibrillarin/genome activation/in-vitro maturation/macaque/oocyte
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Mammalian preimplantation embryogenesis is initially dependent upon maternally-inherited molecules during the early cleavage stages (Bacharova and De Leon, 1980; McLaren, 1981
; Telford et al., 1990
). As development proceeds, and maternally-inherited molecules diminish, the process of embryogenesis becomes dependent upon the expression of genetic information derived from the embryonic genome (Telford et al., 1990
; Tesarik, 1990
). Developmental failure may thus result from insufficient accumulation of developmentally important maternally-derived molecules during development or maturation of oocytes, subsequently leading to cleavage arrest during the maternally-controlled period of development, impairments in the transition from maternal to embryonic control of development, or abnormal pre- or post-implantation gene expression. It has been proposed that failure of timely onset of embryonic transcription may be a common cause of developmental failure of in-vitro produced human embryos (Tesarik, 1987
, 1989a,b; Tesarik et al., 1986b
; Braude et al., 1988
). Because genome activation is thought to be under the control of maternal genome products (Tesarik, 1987
, 1994; Wang and Latham, 1997
), it has been suggested that impairments in genome activation may likely result from incomplete or inadequate cytoplasmic maturation of oocytes (Tesarik, 1987
, 1994; Winston et al., 1991
; Hardy et al., 1993
). Understanding the causes of developmental failure of in-vitro matured primate oocytes may lead to viable strategies for improving their cytoplasmic maturation and subsequent developmental competence.
In macaque, as well as human embryos, genome activation occurs at the 6- to 8-cell stage (Tesarik, 1987; Tesarik et al., 1986a
,b, 1988; Artley et al., 1992
; Weston and Wolf, 1994
; Schramm and Bavister, 1999b
), coincident with the onset of nucleolar rRNA synthesis (Tesarik et al., 1986a
,b, 1987; Schramm and Bavister, 1999b
), and expression of fibrillarin (Schramm and Bavister, 1999b
), a nucleolar protein involved in methylation and processing of pre-rRNA (Kass et al., 1990
; Calzergues-Ferrer et al., 1991
; Kiss-Laszlo et al., 1996
). We hypothesize that incomplete cytoplasmic maturation of oocytes during IVM leads to impairments in genome activation resulting in developmental failure during the embryonically-controlled period of preimplantation development. Specific aims of the this study were to determine whether the timely onset of embryonic genome activation among individual blastomeres of preimplantation embryos is impaired by IVM of oocytes and whether these impairments are associated with stage specific developmental failure in macaque embryos.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
For collection of in-vivo matured oocytes, rhesus monkeys (Macaca mulatta; n = 13) received twice daily i.m. injections of 30 IU recombinant human FSH (rhFSH; Organon Inc., NJ, USA) for 7 days, beginning on days 1 to 3 of the menstrual cycle (day 1 = first day of menstruation). Recombinant hCG (1000 IU; Ares Advanced Technology, NJ, USA) was injected (i.m.) on treatment day 8 for induction of oocyte maturation. Oocytes were aspirated laparoscopically into Tyrodes lactate (TL)-HEPES medium (37°C) containing 0.1 mg/ml polyvinyl alcohol (PVA) and 10 IU/ml heparin 2732 h following injection of hCG. Oocytes were retrieved from aspirates using an EM Con filter (Veterinary Concepts, Spring Valley, WI, USA). Cumulus masses were treated with 0.1% hyaluronidase to facilitate recovery of oocytes. Oocytes were cultured in modified (Boatman, 1987) CMRL-1066 medium; (Connaught Medical Research Laboratories Medium-1066; Invitrogen, Carlsbad, CA, USA) containing 20% bovine calf serum (Hyclone, Logan, UT, USA) at 37°C in a humidified atmosphere of 5% CO2 in air for 48 h prior to insemination.
Immature germinal vesicle (GV) oocytes for IVM, were obtained from both the WNPRC and the CNPRC. Monkeys (n = 28) received rhFSH as described above, but did not receive hCG prior to follicular aspiration (Schramm and Bavister, 1994). Oocytes were retrieved from monkeys either laparoscopically (n = 9; WNPRC) or using ultrasonography (n = 19; CNPRC) on the morning following the last day of rhFSH treatment. Immature oocytes (enclosed by at least three layers of cumulus cells) from each monkey were cultured in one of two types of medium, but not in both. Thus, oocytes cultured in each of the two IVM treatments were obtained during different cycles, as were the in-vivo matured oocytes. All oocytes from the WNPRC were cultured in modified CMRL-1066 medium with or without human gonadotrophins (5 µg/ml hFSH and 10 µg/ml hLH) containing 20% bovine calf serum (CMRLa), as described previously (Morgan et al., 1991
; Schramm et al., 1993
, 1994; Schramm and Bavister, 1994
, 1995, 1996a). At the CNPRC, oocytes from 16 monkeys were cultured in modified CMRL-1066 medium containing hFSH and hLH (0.03 IU/ml Pergonal, Ares-Serono), 10 µg/ml androstenedione (Steraloids, Wilton, NH, USA) and 10% bovine calf serum (CMRLb). Oocytes obtained from three monkeys at the CNPRC were cultured in CMRLa medium with gonadotrophins, as described above. All oocytes were cultured in microdrops under mineral oil at 37°C in a humidified atmosphere of 5% CO2 in air for 2830 h prior to insemination.
IVF/embryo culture
Sperm was collected from adult males by electroejaculation as described previously (Bavister et al., 1983; Sarason et al., 1991
). Sperm capacitation and IVF were done as described previously (Bavister et al., 1983
) with a few minor modifications. Briefly, 10 x 106 washed sperm/ml were resuspended in 2 ml TALP medium and incubated at 37°C in 5 % CO2 in air for 110 h. Sperm were treated with dbcAMP (1mmol/l) and caffeine (1mmol/l) to induce hyperactivation either during (WNPRC) or for 30 min before (CNPRC) co-incubation with oocytes. Sperm (300 000/ml) were co-incubated with oocytes for 1216 h at 37°C in a humidified atmosphere of 5% CO2 in air. Sperm and remaining cumulus cells were then removed manually by pipetting through a finely pulled glass pipette, and oocytes were examined for evidence of fertilization. Embryos used for developmental studies were cultured in HECM-9 medium (McKiernan and Bavister, 2000
) for 48 h, then switched into HECM-9 containing 5% bovine calf serum. Embryos were cultured in 5% CO2, 5% O2 and 90% N2 at 37°C in microdrops under mineral oil and placed into fresh media every other day until zona escape or developmental arrest. Embryos used for genome activation studies were cultured similarly and processed for immunocytochemistry at the 8- to 12-cell stage. Embryos obtained from the CNPRC to be used for genome activation studies were inseminated and cultured to the pronucleate stage, and then loaded into cryovials in equilibrated HECM-9 medium and shipped overnight to the WNPRC in a portable incubator (Minitube, Inc., Madison, WI, USA) at 37°C. Upon arriving at the WNPRC, embryos that had progressed to the 4-cell stage were cultured an additional 24 h (8- to 12-cell stage) before processing for immunocytochemistry. The authors have used this method of shipping embryos extensively and have never observed impairments in subsequent development (R.D.Schramm, unpublished data).
Assessment of nucleolar transcriptional activation in individual blastomeres
Immunocytochemistry for expression of fibrillarin was done as described previously for macaque embryos (Schramm and Bavister, 1999b). Embryos were attached to poly-L-lysine-coated slides, fixed in methanol-free formaldehyde for 1 h and then permeabilized at 37°C in 0.1 mol/l phosphate buffered saline containing 1.0% Triton X-100 (PBS-triton). Following a glycine rinse for reducing free aldehydes, embryos were blocked in PBS-triton containing 3 mg/ml non-fat dry milk (NFDM) and then incubated for 1 h at 37°C with the anti-fibrillarin antibody purchased as the nucleolar pattern component of the Anti-Nuclear Antibody kit (ANA-N; Sigma). After rinsing in PBS-triton-NFDM, embryos were incubated as above in fluorescein isothiocyanate (FITC)-conjugated goat anti-human immunoglobulin diluted in PBS with Evans blue (Sigma). After a rinse in PBS-triton, containing 20 µg/ml Hoechst 33342 (Sigma), specimens were mounted in Vectashield mountant (Vector Laboratories), and stored at 4°C in the dark. Negative controls for background fluorescence were treated as described above, but the primary antibody (ANA-N) was omitted. Whole mounts were examined at 100200x using a Nikon Eclipse TE 300 microscope. Ultra violet and FITC signals were detected using appropriate filter combinations, and photographed with a Nikon 2000 camera mounted on the microscope.
Statistical analyses
Percentages for developmental data, mean regression lines (slopes) for various developmental periods, and numbers of activated cells per embryo were compared using general linear models. Percentage data was arcsine transformed to increase linearity (Sokal and Rohlf, 1995). Post-hoc treatment differences were determined using Fishers least significant difference (LSD) test. Percentages of embryos having no activated cells and
1 non-activated cell were compared using protected Pearson
2 analyses.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
In this study, relatively little developmental failure occurred prior to the time of genome activation in in-vivo or in-vitro matured oocytes, similar to that reported previously for in-vivo matured rhesus oocytes (Schramm and Bavister, 1996b, 1999a). However, earlier studies have shown that significant developmental failure occurred prior to the 8-cell stage in in-vitro matured oocytes obtained from non-stimulated, as opposed to FSH-primed, monkeys (Schramm and Bavister, 1994
, 1995, 1996a, 1999a). Thus, the ability to develop through the maternally controlled period of development may likely be acquired during the later stages of follicular development, even in fully grown oocytes.
The transition from maternal to embryonic control of development occurs at species specific stages and has been commonly referred to as genome activation. It is coincident with this critical stage that preimplantation embryos experience speciesspecific blocks to development in the presence of -amanitin and under various culture conditions in vitro. Since genome activation is thought to be under the control of maternal genome products (Tesarik, 1987
, 1994; Wang and Latham, 1997
), it has been suggested that impairments in genome activation may result from incomplete or inadequate cytoplasmic maturation of oocytes (Tesarik, 1987
, 1994; Winston et al., 1991
; Hardy et al., 1993
). In the present study, we have shown that developmental failure of embryos derived from in vitro matured oocytes (cultured in CMRLa medium) occurred predominantly during the embryonically controlled period of development. Analyses of the developmental regression lines, or slopes, indicate that the rate of developmental failure was similar among treatments through the maternally controlled period of development, but increased dramatically beginning shortly after the time of genome activation in embryos derived from oocytes matured in vitro in CMRLa medium. A similar pattern of developmental failure was recently reported for in-vivo matured oocytes obtained from prenatally androgenized rhesus monkeys, in conjunction with abnormal serum and follicular fluid hormone concentrations both before and after hCG (Dumesic et al., 2002
). Taken together, these data suggest that cytoplasmic impairments in oocytes, incurred during oocyte development or maturation, may subsequently lead to impairments in the transition from maternal to embryonic control of development. Interestingly, although the percentages of oocytes developing into morulae and blastocysts were markedly reduced when matured in CMRLa medium, the developmental slope between the morula and blastocyst stage was similar to that of the other two treatment groups. This implies that IVM derived embryos that succeed in completing the transition from maternal to embryonic control of development are not further impaired in their ability to complete the morula to blastocyst stage transition. This does not however, imply that resulting blastocysts are of equal quality.
The increased incidence of developmental failure after the time of genome activation was not evident in IVM derived oocytes cultured in CMRLb medium, indicating that this medium may provide factors, such as androstenedione, necessary for development through the embryonically driven period of development. Differential effects of in-vitro culture and culture media on gene expression in preimplantation embryos have previously been demonstrated in other species and have been related to developmental abnormalities (Reik et al., 1993; Ho et al., 1994
, 1995; Behboodi et al., 1995
; Doherty et al., 2000
). In order to determine whether developmental failure during the embryonically driven period of development was caused by impairments in embryonic genome activation, we used the expression of fibrillarin in individual blastomeres as a marker for genome activation, as described previously (Pinto-Correia et al., 1995
). In previous studies in rhesus monkeys, the onset of fibrillarin expression mirrored that of tritiated uridine incorporation into the nucleolus, first appearing in 6- to 8-cell stage embryos (Schramm and Bavister, 1999b
). In similar studies in mice (Baran et al., 1995
; Cuadros-Fernandez and Esponda, 1996
), rabbits (Pinto-Correia et al., 1995
; Baran et al., 1997
) and cows (Schramm and Paprocki, 2000b
), nucleolar expression of fibrillarin was first detected at the species-specific time of genome activation, coincident with that of nucleolin, protein B23, RNA polymerase I and the onset of nucleolar transcription (Baran et al., 1995
, 1996; Cuadros-Fernandez and Esponda, 1996
). Results of this study demonstrate that the mean percentages of non-activated blastomeres per embryo, as well as the proportions of embryos with at least one blastomere that had failed to undergo genome activation or with no blastomeres that had undergone genome activation were all significantly greater in embryos derived from oocytes matured in CMRLa than in those matured in CMRLb medium or embryos derived from in-vivo matured oocytes. In fact, 12/27 IVM-derived embryos matured in CMRLa had none of their blastomeres stained, indicative of complete genome activation failure. There were no significant differences in any of these endpoints between embryos derived from in-vivo matured and in-vitro matured CMRLb oocytes. It should be noted that while expression of fibrillarin requires genome activation, it does not neccessarily indicate that activation was complete. Likewise, the absence of fibrillarin expression does not necessarily imply that no aspect of genome activation has occurred. It is also possible that genome activation may have been delayed, rather than failing completely in blastomeres failing to express fibrillarin. Nevertheless, these findings are compatible with the developmental findings above, suggesting that impairments in genome activation may be a prevalent cause of developmental failure in IVM derived primate embryos.
Similar studies have not been done on IVM oocytes in other species. However, autoradiographic studies of tritiated uridine incorporation into IVF embryos obtained from in-vivo matured human oocytes have shown that transcription failure is not uncommon in blastomeres of 8-cell and morula stage embryos (Camous et al., 1986). These blastomeres express very low levels of extranucleolar RNA synthesis and a complete absence of nucleolar RNA synthesis, with up to 30% of blastomeres exhibiting this impairment. The absence of rRNA synthesis in these blastomeres is of particular importance since the embryo must support its demand on protein synthesis using maternally inherited ribosomes, which are rapidly exhausted during the first three cleavage divisions (Tesarik et al., 1986a
). Some of these embryos in which the switch from maternal to embryonic gene activity has failed in a large proportion of blastomeres can progress to the morula stage (Tesarik, 1987
, 1989a,b; Tesarik et al., 1987
) but fail to develop into blastocysts (Tesarik, 1989a,
1994). Similar studies in bovine embryos (Pavlok et al., 1993
) have shown that unlike in 8-cell embryos derived from oocytes from large antral follicles, those derived from oocytes from small (12mm) antral follicles exhibited very low levels of extranucleolar RNA synthesis and the absence of nucleolar RNA synthesis, indicative of a delayed onset of genome activation. This was observed not only among embryos, but also among blastomeres within the same embryo (Pavlok et al., 1993
), and was associated with a high incidence of developmental failure. Taken together, these developmental and molecular findings indicate that the relatively poor developmental competence typical of in-vitro matured human (Cha et al., 1991
, 1992; Barnes et al., 1995
, 1996; Trounson et al., 1998
) and non-human primate (Morgan et al., 1991
; Schramm and Bavister, 1994
, 1995, 1996a, 1999a) oocytes is likely caused, in part, by impairments in the timely onset of embryonic transcription, resulting in developmental failure.
Although the precise mechanisms and components necessary for initiation of embryonic transcription are not known, genome activation may be under the control of maternally inherited factors, such as Oct 4 (Rosner et al., 1990; Abdel-Rahman et al., 1995
), eukaryotic transcription initiation factor (Scholer et al., 1991
; Rosner et al., 1990
; De Sousa et al., 1998
), or the maternal gene factor MATER (Dean, 2002
). Impairments in the transition from maternal to embryonic control of development in IVM derived embryos may have their origins in aberrant expression of genes for these or other maternal factors resulting from incomplete cytoplasmic maturation. Although genome activation failure may contribute to developmental failure in IVM derived embryos, other molecular impairments may also contribute to developmental failure. Some embryos may be impaired in their ability to transcribe some, but not all, embryonically encoded genes (Artley et al., 1992
). In addition, some maternally inherited messages may be involved in the control of cellular events in relatively late stages of human preimplantation development, after genome activation has occurred (Tesarik, 1989a
), and insufficient accumulation of these messages may lead to impairments in the morula to blastocyst stage transition (Renard et al., 1994
; Moor et al., 1998
). The effects of in-vitro culture of oocytes on expression of maternally derived messages and subsequent activation of specific embryonically encoded genes has not been examined in any species.
In conclusion, we have demonstrated that the relatively poor developmental competence of in-vitro matured oocytes is likely caused, in part, by failure in the timely onset of embryonic transcription, resulting from incomplete cytoplasmic maturation during IVM. Identification of specific maternal transcripts and cytoplasmic components acquired during oocyte development and maturation that are essential for normal pre- and post-implantation embryogenesis, will vastly improve our understanding of oocyte cytoplasmic maturation on a molecular level, and how cytoplasmic changes incurred during oocyte development and maturation are subsequently linked to the regulation of embryonic gene expression and preimplantation embryogenesis in primates. Such information will be of tremendous value in formulation of strategies for production of developmentally competent human oocytes by IVM techniques.
![]() |
Acknowledgements |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Artley, J.K., Braude P.R. and Johnson, M.H. (1992) Gene activity and cleavage arrest in human pre-embryos. Hum. Reprod., 7, 10141021.[Abstract]
Bacharova, R. and De Leon, V. (1980) Polyadenylated RNA of mouse ova and loss of maternal RNA in early development. Dev. Biol., 74, 18.[ISI][Medline]
Baran, V., Flechon, J.E. and Pivko, J. (1996) Nucleogenesis in the cleaving bovine embryo: immunocytochemical aspects. Mol. Reprod. Dev., 44, 6370.[CrossRef][ISI][Medline]
Baran, V., Vesela, J., Rehak, P., Koppel, J. and Flechon, J.E. (1995) Localization of fibrillarin and nucleolin in nucleoli of mouse preimplantation embryos. Mol. Reprod. Dev., 40, 305310.[ISI][Medline]
Baran, V., Mercier, Y., Renard, J.P. and Flechon, J.E. (1997) Nucleolar substructures of rabbit cleaving embryos: an immunocytochemical study. Mol. Reprod. Dev., 48, 3444.[CrossRef][ISI][Medline]
Barnes, F.L., Crombie, A., Gardner, D.K., Kausche, A., Lacham-Kaplan, O., Suikkari, A.M., Tiglias, J., Wood, C. and Trounson, A. (1995) Blastocyst development and birth after in vitro maturation of human primary oocytes, intra-cytoplasmic sperm injection and assisted hatching. Hum. Reprod., 10, 32433247.[Abstract]
Barnes, F.L., Kausche, A., Tiglias, J., Wood, C., Wilton, L. and Trounson, A. (1996) Production of embryos from in vitro-matured primary human oocytes. Fertil. Steril., 65, 11511156.[ISI][Medline]
Bavister, B.D., Boatman, D.E., Leibfried, L.M., Loose M. and Vernon, M.W. (1983) Fertilization and cleavage of rhesus monkey oocytes in vitro. Biol. Reprod., 28, 983999.[ISI][Medline]
Behboodi, E., Anderson, G.B., BonDurant, R.H., Cargill, S.L., Kreusche, B.R., Medrano, J.F. and Murray, J.D. (1995) Birth of large calves that developed from in vitro-derived bovine embryos. Theriogenology, 44, 227232.[CrossRef][ISI]
Boatman, D.E. (1987). In vitro growth of non-human primate pre-and peri-implantation embryos. In Bavister, B.D. (ed.) The Mammalian Preimplantation Embryo. Plenum Press, New York, pp. 273308.
Braude, P., Bolton, V. and Moore, S. (1988) Human gene expression first occurs between the four- and eight-cell stages of preimplantation development. Nature, 332, 459461.[CrossRef][ISI][Medline]
Calzergues-Ferrer, M., Mathieu, C., Mariottini, P. and Amalric, F. (1991) Developmental expression of fibrillarin and U3 snRNA in Xenopus laevis. Development, 112, 317326.[Abstract]
Camous, S., Kopecny, V. and Flechon, J.E. (1986) Autoradiographic detection of the earliest stage of [3H]uridine incorporation into the cow embryo. Biol. Cell., 58, 195200.[ISI][Medline]
Cha, K.Y., Koo, J.J., Ko, J.J., Choi, D.H., Han, S.Y. and Yoon, T.K. (1991) Pregnancy after in vitro fertilization of human follicular oocytes collected from nonstimulated cycles, their culture in vitro and their transfer in a donor oocyte program. Fertil. Steril., 55, 109113.[ISI][Medline]
Cha, K.Y., Do, B.R., Chi, H.J., Yoon, T.K., Choi, D.H., Koo, J.J. and Ko, J.J. (1992) Viability of human follicular oocytes collected from unstimulated ovaries and matured and fertilized in vitro. Reprod. Fertil. Dev., 4, 695701.[ISI]
Cuadros-Fernandez, J.M. and Esponda, P. (1996) Immunocytochemical localization of the nucleolar protein fibrillarin and RNA polymerase 1 during mouse early embryogenisis. Zygote, 4, 4958.[ISI][Medline]
De Sousa, P.A., Watson, A.J. and Schultz, R.M. (1998) Transient expression of a translation initiation factor is conservatively associated with embryonic gene activation in murine and bovine embryos. Biol. Reprod., 59, 969977.
Dean, J. (2002) Oocyte-specific genes regulate follicle formation, fertility and early mouse development. J. Reprod. Immunol., 53, 171180.[CrossRef][ISI][Medline]
Doherty, A.S., Mann, M.R.W., Tremblay, K.D., Bartolomei, M.S. and Schultz, R.M. (2000) Differential effects of culture on imprinted H19 expression in the preimplantation mouse embryo. Biol. Reprod., 62, 15261535.
Dumesic, D.A., Schramm, R.D., Peterson, E., Paprocki, A.M., Zhou, R. and Abbott, D.H. (2002) Impaired developmental competence of oocytes in adult prenatally androgenized female rhesus monkeys undergoing gonadotropin stimulation for in vitro fertilization. J. Clin. Endocrinol. Metab., 87, 11111119.
Eppig, J.J. and Schroeder, A.C. (1989) Capacity of mouse oocytes from preantral follicles to undergo embryogenesis and development to live young after growth, maturation and fertilization in vitro. Biol. Reprod., 41, 268276.[Abstract]
Eppig, J.J., Schroeder, A.C. and OBrien, M.J. (1992) Developmental capacity of mouse oocytes matured in vitro: effects of gonadotrophic stimulation, follicular origin and oocyte size. J. Reprod. Fertil., 95, 119127.[Abstract]
Frei, R.E., Schultz, G.A. and Church, R.B. (1989) Qualitative and quantitative changes in protein synthesis occur at the 816-cell stage of embryogenensis in the cow. J. Reprod. Fertil., 86, 637641.[Abstract]
Funahashi, H., Cantley, T. and Day, B.N. (1994) Different hormonal requirements of pig oocyte-cumulus complexes during maturation in vitro. J. Reprod. Fertil., 101, 159165.[Abstract]
Goy, R.W. and Robinson, J.A. (1982) Prenatal exposure of rhesus monkeys to patent androgens: morphological, behavioral and psychological consequences. Banbury Rep., 11, 355378.
Goy, R.W. and Kemnitz, J.W. (1983) Early, persistent and delayed effects of virilizing substances delivered transplacentally to female rhesus monkeys. Raven Press, New York.
Hardy, K., Winston R.M.L. and Handyside, A.H. (1993) Binucleate blastomeres in preimplantation human embryos in vitro: failure of cytokinesis during early cleavage. J. Reprod. Fertil., 98, 549558.[Abstract]
Hirao, Y., Miyano, T. and Kato, S. (1990) Fertilization of in vitro grown mouse oocytes. Theriogenology, 34, 10711077.[ISI]
Hirao, Y., Nagai, T., Kubo, M., Miyano, T., Miyake, M. and Kato, S. (1994) In vitro growth and maturation of pig oocytes. J. Reprod. Fertil., 100, 333339.[Abstract]
Ho, Y., Doherty, A.S. and Schultz, R.M. (1994) Mouse preimplantation embryo development in vitro: effect of sodium concentration in culture media on RNA synthesis and accumulation of gene expression. Mol. Reprod. Dev., 38, 131141.[ISI][Medline]
Ho, Y., Wigglesworth, K., Eppig, J.J. and Schultz, R.M. (1995) Preimplantation development of mouse embryo in KSOM: augmentation by amino acids and analysis of gene expression. Mol. Reprod. Dev., 41, 232238.[ISI][Medline]
Kass, S., Tyc, K., Steitz, J.A. and Sollner-Webb, B. (1990) The U3 small nuclear ribonucleoprotein functions in the first step of pre-ribosomal RNA processing. Cell, 60, 897908.[ISI][Medline]
Kiss-Laszlo, Z., Henry, Y., Bachellerie, J.P., Caizergues-Ferrer, M. and Kiss, T. (1996) Site-specific ribose methylation of pre-ribosomal RNA: a novel function for small nucleolar RNAs. Cell, 85, 10771088.[ISI][Medline]
Kobayahi, K., Yamashita, S. and Hoshi, H. (1994) Influence of epidermal growth factor and transforming growth factor- on in vitro maturation of cumulus cell-enclosed bovine oocytes in defined medium. J. Reprod. Fertil., 110, 3546.
Lanzendorf, S.E., Zelinski-Wooten, M.B., Stouffer, R.L. and Wolf, D.P. (1990) Maturity at collection and the developmental potential of rhesus monkey oocytes. Biol. Reprod., 42, 703711.[Abstract]
Liebfried-Rutledge, M.L., Critser, E.S., Eyestone, W.H., Northey, D.L. and First, N.L. (1987) Development potential of bovine oocytes matured in vitro or in vivo. Biol. Reprod., 36, 376383.[Abstract]
Mattioli, M., Galeati, G. and Seren, E. (1988) Effect of follicle somatic cells during pig oocyte maturation on egg penetrability and male pronucleus formation. Gamete Res., 20, 177184.[ISI][Medline]
McKiernan, S.H. and Bavister, B.D. (2000) Culture of one-cell hamster embryos with water soluble vitamins: pantothenate stimulates blastocyst production. Hum. Reprod., 15, 157164.
McLaren, A. (1981) Analysis of maternal effects on development in mammals. J. Reprod. Fertil., 62, 591596.[CrossRef][Medline]
Mochizuki, H., Fukui, Y. and Ono, H. (1991) Effect of the number of granulosa cells added to culture medium for in vitro maturation, fertilization and development of bovine oocytes. Theriogenology, 36, 973986.[CrossRef][ISI]
Moor, R.M., Dai, Y., Lee, C. and Fulka, J.J. (1998) Oocyte maturation and embryonic failure. Hum. Reprod. Update, 4, 223236.
Morgan, P.M., Boatman, D.E. and Bavister, B.D. (1991) In vitro maturation of ovarian oocytes from unstimulated rhesus monkeys: assessment of cytoplasmic maturity by embryonic development after in vitro fertilization. Biol. Reprod., 45, 8993.[Abstract]
Pavlok, A., Kopecny, V., Lucas-Hahn, A. and Niemann, H. (1993) Transcriptional activity and nuclear ultrastructure of 8-cell bovine embryos developed by in vitro maturation and fertilization of oocytes from different growth categories of antral follicles. Mol. Reprod. Dev., 35, 233243.[ISI][Medline]
Pinto-Correia, C., Long, C.R., Chang, T. and Robl, J.M. (1995) Factors involved in nuclear reprogramming during early development in the rabbit. Mol. Reprod. Dev., 40, 292304.[ISI][Medline]
Reik, W., Romer, I., Barton, S.C., Surani, M.A., Howlett, S.K. and Klose, J. (1993) Adult phenotype in the mouse can be affected by epigenetic events in the early embryo. Development, 119, 933942.
Renard, J.P., Baldacci, P., Richoux-Duranthon, V., Pournin, S. and Babinet, C. (1994) A maternal factor affecting mouse blastocyst formation. Development, 120, 797802.
Rosner, M.H., Vigano, M.A., Ozato, K., Timmons, P.M., Poirier, F., Rigby, P.W.J. and Staudt, L.M. (1990) A POU-domain transcription factor in early stem cells and germ cells of the mammalian embryo. Nature, 345, 686692.[CrossRef][ISI][Medline]
Russell, J.B., Knezevich, K.M., Fabian, K.F. and Dickson, J.A. (1997) Unstimulated immature oocyte retrieval: early versus midfollicular endometrial priming. Fertil. Steril., 67, 616620.[CrossRef][ISI][Medline]
Sarason, R.L., VandeVoort, C.A., Mader, D.R. and Overstreet, J.W. (1991) Electro-ejaculation by direct penile stimulation of restrained but unanaesthetized macaques. J. Med. Primatol., 20, 122125[ISI][Medline]
Scholer, H.R., Ciesiolka, T. and Gruss, P. (1991) A nexus between Oct-4 and E1A: implications for gene regulation in embryonic stem cells. Cell, 66, 291304.[ISI][Medline]
Schramm, R.D. and Bavister, B.D. (1994) FSH-priming of rhesus monkeys enhances meiotic and developmental competence of oocytes matured in vitro. Biol. Reprod., 51, 904912.[Abstract]
Schramm, R.D. and Bavister, B.D. (1995) Effects of granulosa cells and gonadotropins upon nuclear and cytoplasmic maturation in vitro of oocytes from nonstimulated rhesus monkeys. Hum. Reprod., 10, 887895.[Abstract]
Schramm, R.D. and Bavister, B.D. (1996a) Granulosa cells from follicle-stimulating hormone-primed monkeys enhance developmental competence of in vitro matured oocytes from nonstimulated rhesus monkeys. Hum. Reprod., 11, 16981702.[Abstract]
Schramm, R.D. and Bavister, B.D. (1996b) Development of in-vitro-fertilized primate embryos into blastocysts in a chemically defined, protein-free medium. Hum. Reprod., 11, 16901697.[Abstract]
Schramm, R.D. and Bavister, B.D. (1999a) A macaque model for studying mechanisms controlling oocyte development and maturation in human and non-human primates. Hum. Reprod., 14, 25442555.
Schramm, R.D. and Bavister, B.D. (1999b) Onset of nucleolar and extranucleolar transcription and expression of fibrillarin in macaque embryos developing in vitro. Biol. Reprod., 60, 721728.
Schramm, R.D. and Paprocki, A.M. (2000a) Birth of rhesus monkey infant after transfer of embryos derived from in vitro matured oocytes. Hum. Reprod., 15, 24112414.
Schramm, R.D. and Paprocki, A.M. (2000b) Expression of fibrillarin in bovine oocytes and preimplantation embryos developing in vitro. Theriogenology, 54, 15171524.[CrossRef][ISI][Medline]
Schramm, R.D., Tennier, M.T., Boatman D.E. and Bavister, B.D. (1993) Chromatin configurations and meiotic competence of oocytes are related to follicular diameter in nonstimulated rhesus monkeys. Biol. Reprod., 48, 349356.[Abstract]
Sokal, R.R. and Rohlf, F.J. (1995) Biometry, the principles and practice of statistics in biological research. W.H. Freeman and Co., New York.
Telford, N.A., A.J. Watson and G.A. Schultz (1990) Transition from maternal to embryonic control in early mammalian development: a comparison of several species. Mol. Reprod. Dev., 26, 90100.[ISI][Medline]
Tesarik, J. (1987). Gene activation in the human embryo developing in vitro. In Feichtinger, W. and Kemeter, P. (eds) Future Aspects in Human in vitro Fertilization. Springer-Verlag, Berlin and Heidelberg, pp. 251261.
Tesarik, J. (1989a) Involvement of oocyte-coded message in cell differentiation control of early human embryos. Development, 105, 317322.[Abstract]
Tesarik, J. (1989b) Viability assessment of preimplantation concepti: a challenge for human embryo research. Fertil. Steril., 52, 364366.[ISI][Medline]
Tesarik, J. (1990). Genetics of human preimplantation development: implications in embryo viability testing. In Mashiach, S., Ben-Rafael, Z., Laufer, N. and Schenker, J.G. (eds) Advances in Assisted Reproductive Technologies, Plenum Press, New York, pp. 919928.
Tesarik, J. (1994). Developmental failure during the preimplantation period of human embryogenesis. In Van Blerkom, J. (ed.) Biological Basis of Early Human Reproductive Failure: Applications to Medically-assisted Conception, Oxford University Press, New York, pp. 326344.
Tesarik, J., Kopecny, V., Plachot, M. and Mandelbaum, J. (1986a) Activation of nucleolar and extranucleolar RNA synthesis and changes in the ribosomal content of human embryos developing in vitro. J. Reprod. Fertil., 78, 463470.[Abstract]
Tesarik, J., Kopecny, V., Plachot, M. and Mandelbaum, J., DaLage, C. and Flechon, J.E. (1986b) Nucleologenesis in the human embryo developing in vitro: ultrastructural and autoradiographic analysis. Dev. Biol., 115, 193203.[CrossRef][ISI][Medline]
Tesarik, J., Kopecny, V., Plachot, M. and Mandelbaum, J. (1987) High-resolution autoradiographic localization of DNA-containing sites and RNA synthesis in developing nucleoli of human preimplantation embryos: a new concept of embryonic nucleologenesis. Development, 101, 777791.[Abstract]
Tesarik, J., Kopecny, V., Plachot, M. and Mandelbaum, J. (1988) Early morphological signs of embryonic genome expression in human preimplantation development as revealed by quantitative electron microscopy. Dev. Biol., 128, 1520.[ISI][Medline]
Trounson, A.O., Anderiesz, C., Jones, G.M., Kausche, A., Lolatgis, N. and Wood, C. (1998) Oocyte maturation. Hum. Reprod., 13, 5262.[Medline]
Vanderhyden, B.C. and Armstrong, D.T. (1990) Effects of gonadotropins and granulosa cell secretions on the maturation and fertilization of rat oocytes in vitro. Mol. Reprod. Dev., 26, 337346.[ISI][Medline]
VandeVoort, C.A. and Tarantal, A.F. (2001) Recombinant human gonadotropins for macaque superovulation: Repeated stimulations and post-treatment pregnancies. J. Med. Primatol., 30, 304307.[CrossRef][ISI][Medline]
Wang, Q. and Latham, K.E. (1997) Requirement for protein synthesis during embryonic genome activation in mice. Mol. Reprod. Dev., 47, 265270.[CrossRef][ISI][Medline]
Weston, A.M. and Wolf, D.P. (1994) Timing of the maternal to embryonic transition in rhesus monkey embryos. Biol. Reprod., 50,
Winston, N.J., Braude, P.R., Pickering, S.J., George, M.A., Cant, A., Currie, J. and Johnson, M.H. (1991) The incidence of abnormal morphology and nucleocytoplasmic ratios in 2-, 3- and 5-day human pre-embryos. Hum. Reprod., 6, 1724.[Abstract]
Wolf, D.P., C.A. VandeVoort, G.R. Meyer-Haas, M.B. Zelinski-Wooten, D.L. Hess, W.L. Baughman and R.L. Stouffer (1989) In vitro fertilization and embryo transfer in the rhesus monkey. Biol. Reprod., 41, 335346.[Abstract]
Zhang, X., Zerafa, A., Wong, J., Armstrong, D.T. and Khamsi, F. (1993) HMG during in vitro maturation of human oocytes retrieved from small follicles enhances in vitro fertilization and cleavage rates. Fertil. Steril., 59, 850853.[ISI][Medline]
Submitted on August 30, 2002; resubmitted on November 21, 2002; accepted on December 4, 2002.