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PubMed2001

Endocrine profiles and embryo quality in Japanese black cattle superovulated with human menopausal gonadotrophin and porcine follicle stimulating hormone.

Induction of superovulation using human menopausal gonadotriphin (hMG) in Japanese Black cattle can result in the recovery of a higher percentage of high quality embryos compared with that using porcine follicle stimulating hormone (FSH). In order to clarify the endocrinological mechanism involved in this discrepancy, 30 superovulation sessions of 17 Japanese Black cattle were studied. Fifteen cattle were super-stimulated with hMG (total 600 IU), and the remaining 15 cattle were given FSH (total 20 mg). The plasma profiles of LH, estradiol-17beta (E2) and progesterone (P4) were correlated, and the embryo quality was investigated. The total number of ova recovered and the number of transferable embryos tended to be larger in the hMG-treated group than in the FSH-treated group. The percentage of excellent embryos tended to be higher in the hMG-treated group than in the FSH-treated group (54.3 and 28.7%, respectively, p < 0.10). The E2 level increased during the first 3 days after the initial administration of either hMG or FSH and was higher in the hMG-treated group than in the FSH-treated group (p < 0.05). During this period, the E2 level could be categorized into one of the following three types according to whether it increased or decreased and according to the degree of increase or decrease: (1) increase by a factor of 1.2 or more (quick increase type) (2) slight increase by a factor less than 1.2 (slow increase type), and (3) no increase (unstable increase type). In the group treated with hMG, 66.7% of the animals (10 of 15 cattle) showed a quick increase in the E2 level. However, in the FSH-treated group, 40% (six of 15) of the animals showed a slow increase in the E2 level. The plasma LH level increased dramatically 8 h prior to the peak level in both the hMG- and FSH-treated groups, and then it returned to the basal level 12 h later. After the administration of prostaglandin (PG)F2alpha, the LH peak level was attained within 44 h in 80% of the animals in the hMG-treated group, whereas in the FSH-treated group, the LH peak level tended to be reached later. The P4 level did not increase during the period of hMG or FSH treatment and decreased drastically following administration of PGF2alpha. After the onset of oestrus, the P4 level was higher in the hMG group than in the FSH group, and 5 to 7 days after oestrus, the level remained higher in the hMG group than in the FSH group (p < 0.05). After the first 3 days of hMG administration, the E2/P4 ratio was higher than that after FSH administration. Furthermore, on the day following PGF2alpha administration, the ratio was significantly higher in the hMG group than in the FSH group (p < 0.05). These results indicate that superovulation in cattle given hMG results in a significant increase in plasma E2 during the first 3 days and that the increase in the plasma P4 level is larger a few days after oestrus and thereafter compared with FSH-induced superovulation. Therefore, such plasma level profiles may be related to the increased recovery rate of high quality embryos.

Animals↗

PubMed1997

A somatostatin analogue decreases embryonic loss following superovulation in rats by normalizing insulin-like growth factor-I action in the uterus.

This study was designed to determine whether the somatostatin analogue, octreotide, could prevent embryonic loss by normalizing increased uterine insulin-like growth factor-I (IGF-I) action related to hyperoestrogenaemia following superovulation. Superovulated immature and oestradiol-17beta-treated adult rats were infused with 100 or 300 microg/ml of octreotide respectively, or injected daily with 1 or 10 microg of octreotide from day 1 to day 3 of pregnancy. On day 3, embryos were collected from the oviducts and uteri. Uterine luminal fluid was subjected to embryo culture. The amounts of uterine IGF-I and IGF binding proteins (IGFBP) were determined by radioimmunoassay and ligand binding assay respectively. Octreotide infusion normalized uterine IGF-I action following superovulatory and oestradiol-17beta treatment, by reducing IGF-I concentrations and increasing IGFBP concentrations. Octreotide infusion increased the number of normal embryos by 2.7-fold and 1.7-fold in superovulated and oestradiol-17beta-treated rats respectively, and reversed the detrimental effects of uterine luminal fluid on embryonic development caused by superovulatory and oestradiol-17beta treatment. Daily injections with octreotide had similar but reduced effects in all parameters examined in both treatment groups. In conclusion, octreotide may reduce embryonic loss, at least in part, by normalizing IGF-I action following superovulation.

Animals↗

PubMed2006

Aberrant DNA methylation of imprinted loci in superovulated oocytes.

BACKGROUND: There is an increased incidence of rare imprinting disorders associated with assisted reproduction technologies (ARTs). The sex-specific epigenetic modifications that are imposed during gametogenesis act as a primary imprint to distinguish maternal and paternal alleles. The most likely candidate for the gametic mark is DNA methylation. However, the timing of DNA methylation acquisition in adult oocytogenesis and the effects of superovulation are unknown. METHODS: We examined the maternal methylation of PEG1(MEST), LIT1(KCNQ1OT1) and ZAC(PLAGL1) and the paternal methylation of H19 in adult growing oocytes of humans and mice and compared them with the methylation status of mouse neonatal growing oocytes by using bisulphite sequencing. Furthermore, we examined the effects of superovulation in the human and mouse. RESULTS: Maternal methylation of these genes has already been initiated to some extent in adult human and mouse non-growing oocytes but not in mouse neonates. In addition, the methylation dynamics during adult human and mouse oocyte development changed more gradually than those during neonatal oocyte development. Furthermore, we found the demethylation of PEG1 in growing oocytes from some ART-treated infertile women and a gain in the methylation of H19. We also detected methylation changes in superovulated mice. CONCLUSION: Our studies in the human and mouse suggest that superovulation can lead to the production of oocytes without their correct primary imprint and highlight the need for more research into ARTs.

Adult↗

PubMed1995

Gonadotropin surge-attenuating factor bioactivity in serum from superovulated women is not blocked by inhibin antibody.

Primary pituitary cultures from adult female rats were used to investigate gonadotropin surge attenuating factor (GnSAF) bioactivity. Serum from superovulated women was charcoal-treated and incubated with either an inhibin antibody (MC4), normal sheep serum (NSS), or serum-free defined medium (SFDM) before addition to cell culture. The reduction in GnRH-induced LH secretion (GnSAF bioactivity) produced by the serum (30.1 +/- 6.5%, p < 0.001, of control) was not altered by prior incubation with either MC4 or NSS (24.9 +/- 3.6 and 23.2 +/- 2.7%, p < 0.001, of control, respectively). This indicates that GnSAF bioactivity present in serum from superovulated women is not entirely attributable to inhibin. Recombinant human inhibin reduced basal FSH secretion to 24.6 +/- 4.7% (p < 0.001) of the control value. However, this was totally abolished by prior incubation with MC4, but not NSS. We have also shown that ovarian steroids are not responsible for GnSAF bioactivity in vitro. In conclusion, in contrast to findings in superovulated rats, inhibin antibody did not block GnSAF bioactivity in serum from superovulated women.

Animals↗

PubMed1995

Superovulation and intrauterine insemination in the treatment of male factor infertility.

Recent studies report that superovulation combined with intrauterine insemination (IUI) is more successful than superovulation alone, IUI alone or superovulation with intracervical insemination in couples with male subfertility. Our study evaluated two superovulation protocols in the management of male factor infertility using IUI: (A) clomiphene citrate and human chorionic gonadotropin (HCG) and (B) human menopausal gonadotropin and HCG. Fifteen couples with severe oligoasthenozoospermia (OAS) were treated with protocol A in 54 cycles, and no pregnancies were achieved. Eight of the 15 couples with severe OAS subsequently received protocol B for 24 cycles and elicited no pregnancies. Thirty-seven couples with moderate OAS received protocol A for 169 cycles, and 2 pregnancies ensued (5.4% per couple and 1.12% per cycle). Twelve of the 35 nonpregnant couples with moderate OAS then received protocol B for 31 cycles, and 4 pregnancies were recorded (33.3% per couple and 12.9% per cycle).

Adult↗

PubMed1993

Continuous luteinizing hormone infusion prevents atretic changes of the follicles during superovulation in hamsters.

Superovulation with exogenous gonadotropins has been used widely to study the reproductive events in animals and in vitro fertilization and embryo transfer in human beings. However, details of the mechanism of superovulation are not yet clearly understood. The present study was conducted to study the mechanism of superovulation with purified human FSH and LH preparations. Cyclic hamsters received continuous infusion of purified FSH and LH for 4 days, from estrus to proestrus. The number of ova shed was significantly increased by 5 iu FSH/minipump infusion, and further increased by 5 iu FSH/minipump plus 5 iu LH/minipump group. On the other hand, the number of atretic follicles was decreased significantly (P < 0.01) by the combined infusion of FSH and LH, but not by FSH alone. Among these experimental groups, there was no significant difference in embryonic development which was assessed by the counting of the number of 4-cells and more developed embryos on day 3 of pregnancy. These data indicated the different roles of FSH and LH in the superovulation process, because FSH stimulated some small follicles to grow and LH, in the presence of FSH, rescued the follicles to undergo atresia.

Animals↗

PubMed1980

Radiolabelled uterine proteins during early pregnancy and pseudopregnancy in mice after unilateral ovariectomy and superovulation.

Uterine secretions were analysed after labelling in vivo with L-[4,5-3H]leucine. The acid-precipitable counts were highest on Day 1 p.c., low on Day 2, lowest on Day 3, and similar to Day 2 values on Day 4 p.c. After unilateral ovariectomy the acid-precipitable counts for the horn ((+)ovary) ipsilateral to the remaining ovary were higher than those in the contralateral horn ((-)ovary) for each condition studied. Superovulation yielded slightly higher acid-precipitable counts in the (-)ovary and (+)ovary horns of pregnant mice on Day 3 p.c., and in the (+)ovary horn only for pseudopregnant mice on Day 2 p.c. The Day 2 counts for the (+)ovary and (-)ovary horns of the superovulating pseudopregnant mice were higher counts than those for superovulating pregnant mice, but the reverse occurred for (+)ovary horns only on Day 4 p.c. No qualitative differences between pseudopregnant and pregnant mice were observed on Day 4 and superovulation appeared to enhance the profiles obtained.

Animals↗

PubMed1987

Comparison of subpopulations of luteal cells obtained from cyclic and superovulated ewes.

Peripheral blood samples were collected daily (Days 1-10 after ovulation) and analysed for progesterone content. Luteal tissue was collected on Day 10 after the LH surge, or Day 10 after hCG injection from cyclic and superovulated ewes, respectively. The tissue was enzymically dispersed and an aliquant was utilized for measurement of cell diameters, and staining for 3 beta-hydroxy-delta 5-steroid dehydrogenase-delta 5, delta 4-isomerase activity (3 beta-HSD). The remaining cell preparation was separated into small (10-22 micron) and large (greater than 22 micron) cell fractions by elutriation. Small and large cell suspensions were incubated (37 degrees C, 2 h) in the presence or absence or ovine LH (100 ng/ml) or dbcAMP (2 mM) and progesterone content of the medium was measured. Superovulation did not affect circulating progesterone concentrations, when expressed per mg luteal tissue recorded; basal progesterone production by small or large luteal cells; the unresponsiveness of large luteal cells to ovine LH or dbcAMP; the ratio of small:large cells recovered by dissociation the mean diameter of total cells; or the mean diameter of large cells. However, the mean cell diameter and LH stimulation of progesterone production by small cells were greater (P less than 0.05) in luteal tissue collected from superovulated than in that from cyclic ewes. These differences appear to be an amplification of basic function. Therefore, we conclude that corpora lutea obtained from superovulated ewes can be used to study functional aspects of small and large cells.

3-Hydroxysteroid Dehydrogenases↗

PubMed1994

Assessment of the presence of a dominant follicle and selection of dairy cows suitable for superovulation by a single ultrasound examination.

The physiological significance of the dominant follicle (> 9 mm in diameter in a growing phase; stable for < 3 days) for the superovulatory response in 117 lactating Holstein Friesian dairy cows was investigated. The presence or absence of a dominant follicle was determined retrospectively by analysing videotapes of follicular growth in all the ovaries. Superovulation was induced by 28 mg Armour units (400 mg NIH-FSH-P1) of FSH (Folltropin) administered either twice or once a day i.m. over 4 days in a decreasing regimen or as a single injection s.c. Donors were scanned daily from day 3 after the oestrus preceding superovulation until embryo recovery. In Expt 1 donors superovulated (two times a day for 4 days) in the absence of a dominant follicle yielded more corpora lutea (11.7 +/- 0.9 versus 4.7 +/- 1.1, P < 0.01), ova and embryos (8.2 +/- 1.2 versus 2.8 +/- 1.0, P < 0.01) and transferable embryos (5.0 +/- 1.0 versus 2.1 +/- 0.9, P < 0.05) compared with donors treated in the presence of a dominant follicle. In Expts 2 and 3 donors were scanned only on the day of superovulation and donors with < 10 follicles 3-8 mm in diameter were considered to have a dominant follicle, while donors with > or = 10 small follicles 3-8 mm in diameter were classified as having no dominant follicle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

Superovulation induction in the house musk shrew (Suncus murinus).

The number of ovulated oocytes in the adult house musk shrews was examined by natural mating. The positive rate of ovulation was 83.3%, and the mean number of ovulated oocytes was 4.4 +/- 1.9 (Mean +/- SD). The induction of superovulation was examined by administering either pregnant mare's serum gonadotropin (PMSG) or human chorionic gonadotropin (hCG), exogenous gonadotropin, to house musk shrews. As a result, the number of ovulated oocytes were within the number of oocytes ovulated spontaneously. The method of superovulation induction by administering both PMSG and hCG to house musk shrews was investigated. In the group intraperitoneally with 7.5 i.u. of PMSG followed by 7.5 i.u. of hCG 48 hr later, the positive rate of ovulation was as high as 94.6% and the mean number of ovulated oocytes was 11.7 +/- 13.4. Moreover, in 15 out of these 35 animals positive for ovulation, 10 oocytes or more were observed and the mean number of ovulated oocytes was 21.0 +/- 16.5, showing the superovulatory response. In the group of 5.0 i.u. PMSG and 5.0 i.u. hCG injected at an interval of 72 hr, every animal was induced to ovulate and the mean number of ovulated oocytes was 41.3 +/- 19.9. Thus, the injection of PMSG and hCG at a longer interval increased the number of superovulated oocytes. Furthermore, 97.5% of eggs recovered from superovulating animals contained cumulus cells.

Animals↗

PubMed2006

Variation with age in the numbers of ovulated ova and follicles of Wistar-Imamichi adult rats superovulated with eCG-hCG.

There are large variations with age in the number of ovulated ova found in superovulated female Wistar-Imamichi rats. In this study we investigated the numbers of ovulated ova and follicles with the aim of developing a superovulation technique that minimises variations. We also examined the number of non-atretic follicles in untreated rats aged 7-14 weeks, for each week of age. The numbers of 250-549 microm non-atretic follicles in untreated rats and the numbers of ovulated ova in superovulated rats both reached a peak at 12 weeks of age. The coefficients of variation for both follicle numbers and ova numbers changed with each week of age, reaching a maximum at 9 weeks of age and a minimum at 12 weeks of age. In order to achieve stable numbers of ova from superovulated rats, satisfactory results will be achieved using 12-week-old rats, minimising individual variations, with high numbers of ova.

Aging↗

PubMed1995

Factors affecting the developmental stage of embryos recovered on day 7 from superovulated dairy cattle.

The objective of this retrospective study was to evaluate the factors influencing developmental stage of bovine embryos recovered from superovulated dairy cattle 7 d after estrus. From 217 superovulated dairy cows and heifers, 2,211 eggs were recovered, of which 1,495 were classified as transferable embryos based on morphological evaluation of developmental stage and quality. From the evaluated embryos, 1,429 were non-surgically transferred to recipients to produce 623 calves. The transferable embryos were classified into five developmental stages and four quality grades. The least-developed transferable embryos tended to be classified into poorer quality grades. A multifactorial statistical model was used to analyze whether the following factors were associated with the developmental stage and quality grade of the embryos: donor breed, parity, gonadotropin preparation, embryo sex, insemination bull, embryologist (the person evaluating the embryo), year, and season of recovery. Among these factors, only the embryologist and the donor animal accounted for significant variation in embryo development. It was concluded that the developmental stage of embryos recovered at d 7 from superovulated cattle, when evaluated by simple morphological criteria, was correlated with the embryo's quality and was affected by the donor animal but in this study not by the embryo sex, donor breed and parity, gonadotropin preparation, and insemination bull used. The embryo's quality grading was influenced by the embryologist. Consequently, sexing of an embryo recovered from superovulated cattle is not possible by simple morphological evaluation of the embryo's developmental stage.

Animals↗

PubMed1992

Development of mouse oocytes superovulated at different ages.

The development of oocytes superovulated at 25, 50, or 90 days in four mouse strains (C57BL/6N, DBA/2N, ICR, and B6D2F1) was examined using the techniques of in vitro fertilization, culture, and transfer of two-cell embryos to pseudopregnant recipients. The highest number of ova were obtained from superovulated 25-day-old mice in all strains. Approximately 80% of oocytes developed to the two-cell stage after in vitro fertilization. Of these living oocytes, 60% developed to weanling stage through the recipient. These results suggested that donor age among 25, 50, or 90-day-old mice has no influence on the viability of superovulated oocytes. Consequently, we conclude that superovulated 25-day-old mice offer an economical and efficient source of viable oocytes for the production of transgenic mice.

Age Factors↗

PubMed1992

[Descent of ova and embryos in cows superovulated with serum gonadotropin].

The descent and localization of eggs and embryos in individual segments of the reproductive tract of superovulated cows were studied in this work. For the induction of superovulation, serum gonadotropin (PMSG, Ivanovice in Haná) at a dose of 2,500-3,500 I.U. was used, in combination with 0.5 mg of Cloprostenol (Oestrophan, Spofa), administered 48 hours after gonadotropin treatment. The start of superovulation fell on days 9 to 12 of the sexual cycle and was conditioned by the presence of the corpus luteum (CL). After the onset of the heat, 2-3 inseminations were carried out using fresh semen. Donor cows were slaughtered 3, 4, 5, 6, and 7 days after the second insemination and isolated reproductive organs (Fig. 1) were divided into five segments (two on oviducts and three on uterine horns) by the applied ligature. In laboratory conditions superovulation response was determined accurately, the volume of ovaries was assessed according to water displacement and the segments of oviducts and uterus were rinsed with TCM 199 or PBS supplemented with FCS. 3, 4, 5, 6, and 7 days after insemination (Tab. I). 18.1 (+/- 3.55), 12.4 (+/- 0.91), 19.2 (+/- 2.86), 20 and 23 (+/- 2.44) CL on average were recorded, which corresponded to the ovulation of 64, 50, 56, 71 and 72 percent of stimulated follicles (Fig. 2). Within 3 to 7 days after insemination nearly triple enlargement of ovaries was also observed (Tab. I, Fig. 3). During the lavage of individual segments of the tubular reproductive tract, 38 per cent of eggs and embryos were detected in the uterus as early as 3 days after insemination (Tab. II). Unfertilized eggs and degenerated embryos were found in the 2nd and 3rd uterine segment, embryos at the stage of 8-16 blastomeres were localized in the 1st and 2nd segment of the uterus. Four days after insemination (Tab. III), about 64 per cent of eggs and embryos at the stage up to 16 blastomeres were found in the uterus, but embryos up to 32 blastomeres were still flushed out of the oviduct. On day 5 after insemination, 92 per cent of eggs and embryos were released into the uterus, being localized mostly in the cranial and medial part of the uterus (Tab. IV). 7.5 per cent of recovered eggs and embryos at the stage of early or compacted morulae were still detected in the oviducts.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1993

Use of superovulated mice as embryo donors for ES cell injection chimeras.

We examined whether superovulation can be used to improve the efficiency of donor embryo collection in embryonic stem cell injection chimera experiments. Superovulation of prepuberal C57BL/6 mice was compared with spontaneous ovulation of mature mice with respect to production and survival of blastocysts. Our results indicate that, compared with spontaneous ovulation, superovulation results in an increased number of blastocysts per female with no difference in viability when transferred to outbred Swiss Webster foster mothers. The advantage of using superovulated females, in terms of maintaining smaller numbers of both females and stud males, is discussed.

Animals↗

PubMed1994

Morphological and hormonal changes after superovulation in cows treated with Neutra-PMSG.

Morphological changes in ovaries and hormonal changes as well as changes in Na, K, Ca, Mg, and P blood plasma levels were observed after superovulation induced by the administration of PMSG and the neutralization of this hormone with monoclonal antibodies Neutra-PMSG administered either 72 or 108 h later. The introduction of Neutra-PMSG 108 h after PMSG injection clearly decreases the number of surviving non-ovulated follicles with a diameter > 10 mm (1.7 +/- 0.8 vesicle in an individual cow on the average) in comparison to the group without Neutra-PMSG (19.4 +/- 9.5). The efficiency of ovulation in the group treated with Neutra-PMSG in the 108th h of the experiment (8.2 +/- 4.6 corpora lutea per cow on the average), did not differ statistically from the group treated with PMSG only (12.4 +/- 10.6). Early administration of Neutra-PMSG (72h), totally inhibits superovulation. Observations showed, that injection of Neutra-PMSG in the 108th h, caused a considerable decrease in the estradiol level, beginning with the 120th h of the experiment. Determination of the progesterone blood plasma level reflects the number of corpora lutea and can be helpful in evaluating the effects of superovulation. Superovulation did not effect the level of Na, K, Ca, Mg, and P in the blood plasma.

Animals↗

PubMed1996

Changes in lysosomal enzyme activities in pre-ovulatory follicles and endometrium of PMSG superovulated rats.

Large superovulatory doses of gonadotrophins result in reduced fertility in laboratory and large domestic animals and it has been postulated that some of the superovulated oocytes are derived from abnormal follicles which would not ovulate under normal physiological stimuli. Follicular growth, follicular maturation and atresia, ovulation and the nidation of the fertilized oocyte require intense tissue remodelation which can be accomplished only through the action of hydrolytic enzymes. We have studied the activities and sub-cellular distribution of three lysosomal enzymes (acid phosphatase, N-acetyl-beta-D-glucosaminidase and beta-glucuronidase) in the follicular fluid, granulosa and theca cells of preovulatory follicles and in the endometrial tissue of immature Wistar rats injected with 4 (control) or 40 (superovulated) IU of pregnant mare serum gonadotrophin (PMSG). Enzyme activities were from four to ten times higher in theca than in granulosa cells. This difference was particularly important in the case of beta-glucuronidase. Large preovulatory follicles tended to have higher activities of lysosomal enzymes in the free fraction of all the compartments studied. This difference was remarkable in theca cells where free enzymes would be required to help ovulation. Forty IU of PMSG induced higher activities of acid phosphatase in theca and granulosa cells than 4 IU, but in endometrial tissue this latter dose of PMSG was more efficient to induce higher activities of this enzyme. The endometrial bound fraction of N-acetyl-beta-D-glucosaminidase was almost three times higher than the free activity. This behavior was also observed in endometrial beta-glucuronidase but only in the control rats. The results observed in follicular fluid were less homogeneous. The activities of glucosaminidase and acid phosphatase were two to three times higher in rats overstimulated with 40 IU of PMSG than in the control rats, whereas the activities of beta-glucuronidase were lower in the superovulated rats. Our results suggest that alterations in the process of tissue remodeling required for ovulation of mature, normal oocytes and for nidation of the fertilized ovum may be important factors to explain pregnancy failure in the PMSG superovulated female.

Animals↗

PubMed1989

Preimplantation embryo development and serum steroid levels in immature rats induced to ovulate or superovulate with pregnant mares' serum gonadotropin injection or follicle-stimulating hormone infusions.

Follicular stimulation protocols using pregnant mares' serum gonadotropin (PMSG) or a follicle-stimulating hormone (FSH) preparation were compared to evaluate the yield and quality of embryos obtained from immature rats. Rats received a superovulatory dose of PMSG (40 IU), a nonsuperovulatory dose of the same gonadotrophin (4 IU), or a continuous s.c. infusion over a 72-h period with a purified FSH preparation containing an optimum ratio of luteinizing hormone (LH): FSH (FSH-hCG). The females were caged with fertile males on the evening of the 3rd day of gonadotropin treatment and scored for the occurrence of mating on the next morning; subgroups were killed on days 1-4 of pregnancy. High fertilization rates were observed in rats treated with 4 IU PMSG (84.1%) and in rats infused with FSH-hCG (91.0%); however, a much lower fertilization rate was observed following treatment with 40 IU PMSG (41.5%). From median ovulation rates of 9 and 79 in rats treated with 4 IU PMSG and in rats infused with FSH-hCG, medians of 8 and 69 embryos, respectively, were recovered from reproductive tracts flushed on day 4 of pregnancy, from which 75% were morulae or blastocysts; in contrast, from a median ovulation rate of 42.5, a median of only 12 embryos was recovered on day 3 of pregnancy following superovulation with 40 IU PMSG of which 80% were degenerate ova. Serum steroid profiles during the first 4 days of pregnancy differed significantly among treatment groups, the major differences being in substantially elevated levels of estradiol and androgens on days 1-3 in rats receiving the high (40 IU) dose of PMSG. Levels of these steroids in rats superovulated with the FSH-hCG infusion regimen were only marginally elevated above levels observed in rats treated with the low (4 IU) nonsuperovulatory dose of PMSG. Consistent with high ovulation rates, serum progesterone levels rose to considerably higher levels during the period in both superovulated groups than in animals receiving the low, nonsuperovulatory dose of PMSG. This work describes a novel method to superovulate rats (FSH-hCG) leading to high yields of normally developing embryos at all preimplantation stages and illustrates the close association between high yield of embryos and low levels of circulating androgens and estradiol-17 beta during the preimplantation period.

Animals↗