Breast levonorgestrel concentrations in women using a levonorgestrel-releasing intrauterine system

OBJECTIVE

To measure breast tissue and serum LNG concentrations in women using a LNG-IUS.

STUDY DESIGN

This pilot study was performed in 25 healthy women undergoing breast surgery at the Ghent University hospital. LNG concentrations were measured in serum and microdissected breast tissue samples using a validated ultra-performance liquid chromatography/tandem mass spectrometry assay.

RESULT(S)

The mean LNG concentration in the 18 LNG-IUS users was 0.18±0.16 ng/mL in serum and 0.26±0.28 ng/g in breast tissue. For four women without any form of hormonal contraceptive (the negative controls), the mean concentrations were below the limit of quantification, i.e., 0.15 ng/mL and 0.20 ng/g, for serum and breast tissue, respectively. For the three positive controls the concentrations in the serum (20.5 and 3.4 ng/ml) and the breast (3.74 and 1.24 ng/g) were respectively for the 20 μg EE/100 μg users and 315 pg/ml in the serum and 1.17 ng/g in the breast for the minipill user. The intracellular free fraction of LNG may be as low as 0.008 ng/g.

CONCLUSION(S)

The concentration of LNG in breast epithelium cells in women using the LNG-IUS is very low.

IMPLICATIONS

The relationship between the serum and breast tissue levels of LNG was studied in women using a LNG-IUS or oral LNG-containing contraception. Compared to oral contraception, the tissue levels of LNG in LNG-IUS users are much lower in the breast. It is not known what level of LNG exposure in the breast would stimulate RANKL and WNT4 expression; such information is needed.

Herbal preparations for the menopause: beyond isoflavones and black cohosh

Complementary and alternative medicines (CAM) such as isoflavones and black cohosh are commonly used to deal with menopausal symptoms, but benefit a limited proportion of women. The aim of this minireview is to summarize the evidence of the efficacy and safety of other herbal preparations. Randomized controlled trials (RCTs) find that the extracts of Mediterranean pine bark (Pycnogenol(®)), linseed, and Lepididium meyenii (Maca) reduce vasomotor symptoms. The results of RCTs of the hop flavonoid 8-prenylnaringenin are conflicting. Animal and human studies suggest that Dioscorea villosa (Wild yam),and Broccoli may protect against osteoporosis and breast and gynecological cancers but further evidence is required. Linseed may protect against breast cancer but the results are conflicting.

Number of women needed in a prospective trial to prove potential cardiovascular benefit of hormone replacement therapy

INTRODUCTION

Hormonal replacement therapy (HRT) may be beneficial for the cardiovascular system if hormones are given shortly after the onset of menopause. So far, no randomized trial has provided conclusive results.

MATERIALS AND METHODS

Based on Belgian population data, we calculated the number of women that should be included in a prospective double-blinded study to prove a potential cardiovascular benefit of HRT. Sample size calculations were based on the extrapolation of empirical observations made in three large databases from epidemiological studies carried out in Belgium during the past 20 years.

RESULTS

The 10-year mortality varies with the age at which women are included in the observation. In the normal Belgian female population, the cardiovascular mortality risk is 0.85% and 1.58% for women aged 50-54 and 55-59 years, respectively. To prove that HRT induces a decrease of 10-year mortality of 30% in a normal population of 50-54-year-old women, 34 630 subjects would have to be included; for reductions of 20% and 10%, the numbers would be, respectively, 82 468 and 348 056. To prove a significant decrease in 10-year mortality starting with a normal population with an average age of 55-59 years, the numbers needed for hypothetical reductions of 30%, 20% and 10% would be, respectively, 18 514, 44 072 and 185 936.

CONCLUSION

If cardiovascular mortality is the study end-point, it is obvious that such a study will be a gigantic task. Taking cardiovascular morbidity as the end-point, such a study would be feasible.

Plant polyphenolics as anti-invasive cancer agents

Because invasion is, either directly or via metastasis formation, the main cause of death in cancer patients, development of efficient anti-invasive agents is an important research challenge. We have established a screening program for potentially anti-invasive compounds. The assay is based on organotypic confronting cultures between human invasive cancer cells and a fragment of normal tissue in three dimensions. Anti-invasive agents appeared to be heterogeneous with regard to their chemical nature, but plant alkaloids, polyphenolics and some of their synthetic congeners were well represented. Even within this group, active compounds were quite diverse: (+)-catechin, tangeretin, xanthohumol and other prenylated chalcones, 3,7-dimethoxyflavone, a pyrazole derivative, an isoxazolylcoumarin and a prenylated desoxybenzoin. The data gathered in this system are now applied in two projects. Firstly, structure-activity relationships are explored with computer models using an artificial neural network approach, based on quantitative structural descriptors. The aim of this study is the prediction and design of optimally efficient anti-invasive compounds. Secondly, the metabolism of orally ingested plant polyphenolics by colonic bacteria is studied in a simulator of the human intestinal microbial ecosystem (SHIME) and in human intervention trials. This method should provide information on the final bioavailability of the active compounds in the human body, with regard to microbial metabolism, and the feasibility of designing pre- or probiotics that increase the generation of active principles for absorption in the gastro-intestinal tract. The final and global aim of all these studies is to predict, synthesize and apply in vivo molecules with an optimal anti-invasive, and hence an anti-metastatic activity against cancer.

Anti-invasive/anti-metastasis strategies: new roads, new tools and new hopes

Unfortunately, the anticancer drugs that are used nowadays in the clinic have only limited success. To provide a significant clinical advancement, new concepts have to be introduced to aid the design of new tools for therapy. Cancer is not only restricted to neoplastic cells, but rather it involves an ensemble of protagonists. In addition, the evolution of cancer is extremely complex, since multiple cellular activities are involved. Some key steps in the evolution to a metastatic tumor have been shown to be no useful targets. Targeting the stroma cells, however, could bring a new efficiency in anticancer treatment. Targeting the disorganized tissue architecture at the primary site and the restoration of the cell death program in cancer cells appears to create new possibilities in drug design. Also the cytoskeleton, which represents a dynamic set due to its plasticity and multiplicity, seems to be a promising target in anticancer therapy. Moreover, the evolving knowledge of the role of metastasis suppressor genes in regulating cancer cell growth at the secondary site suggests that they could serve as new targets for therapeutic intervention. This review intends to highlight the unraveling of new therapeutic pathways, and to unveil new powerful research tools for combating metastasis.

Tibolone and its metabolites inhibit invasion of human mammary carcinoma cells in vitro

Tibolone is used in postmenopausal women to alleviate menopausal symptoms and to prevent osteoporosis, but it does not stimulate the endometrium and the breast. Up to date, little data are available on the effect of tibolone on breast cancer initiation and progression.

OBJECTIVE

In the present in vitro study, we investigated the effect of tibolone and its metabolites (3alpha-OH tibolone, 3beta-OH tibolone, the Delta4 isomer and the sulphated isoform) on invasion of human breast cancer cells.

METHODS

The effect on invasion was evaluated in the chick heart invasion assay using MCF-7/6 cells and in the collagen type I invasion assay using T47-D cells. Furthermore, the compounds were tested in aggregation and migration assays.

RESULTS

We observed that, at a concentration of 100 microM, tibolone and its 3beta-OH metabolite possess anti-invasive activities in the two different invasion assays. However, this was neither due to effects on cell-cell adhesion nor on motility. In an attempt to probe the mechanism underlying the anti-invasive effect, we found that pro-MMP-9 release was markedly reduced in the supernatant of MCF-7/6 breast cancer cells treated with tibolone, 3alpha-OH tibolone and the Delta4 isomer but, interestingly, not with the sulphated metabolite.

CONCLUSION

We conclude that tibolone and its 3beta-OH metabolite have an anti-invasive effect on the tested breast cancer cell lines in vitro. This effect on invasion is not correlated with an effect on cell-cell adhesion or motility but coincides with a decreased release of pro-MMP-9 in the medium.

Tangeretin inhibits extracellular-signal-regulated kinase (ERK) phosphorylation

Tangeretin is a methoxyflavone from citrus fruits, which inhibits growth of human mammary cancer cells and cytolysis by natural killer cells. Attempting to unravel the flavonoid's action mechanism, we found that it inhibited extracellular-signal-regulated kinases 1/2 (ERK1/2) phosphorylation in a dose- and time-dependent way. In human T47D mammary cancer cells this inhibition was optimally observed after priming with estradiol. The spectrum of the intracellular signalling kinase inhibition was narrow and comparison of structural congeners showed that inhibition of ERK phosphorylation was not unique for tangeretin. Our data add tangeretin to the list of small kinase inhibitors with a restricted intracellular inhibition profile.

A safety study of oral tangeretin and xanthohumol administration to laboratory mice

BACKGROUND

The detection of molecular targets for flavonoids in cell signalling has opened new perspectives for their application in medicine. Both tangeretin, a citrus methoxyflavone, and xanthohumol, the main prenylated chalcone present in hops (Humulus lupulus L.), act on the mitogen-activated protein kinase pathway and await further investigation for administration in vivo.

MATERIALS AND METHODS

A safety study was designed in laboratory mice orally administered concentrates of purified tangeretin (1 x 10(-4) M) or xanthohumol (5 x 10(-4) M) at libitum for 4 weeks. Blood samples were collected for the analysis of a variety of haematological and biochemical parameters.

RESULTS

A reduction of the circulating lymphocyte number was noticed for tangeretin, while all other parameters were unaffected by treatment with either tangeretin or xanthohumol. The parameters encompassed an integrity check of the following tissues and organs: bone marrow, liver, exocrine pancreas, kidneys, muscles, thyroid, ovaries and surrenal cortex. Furthermore, no differences were noted in the metabolism of proteins, lipids, carbohydrates and uric acid, as well as in ion concentrations.

CONCLUSION

All data indicate that oral administration of tangeretin or xanthohumol to laboratory mice does not affect major organ functions and opens the gate for further safety studies in humans.

Distribution of Soy-Derived Phytoestrogens in Human Breast Tissue and Biological Fluids

OBJECTIVE

Soy-derived phytoestrogens may exert several health-beneficial effects. Although plasma and urine levels of these compounds after ingestion have been thoroughly investigated, little is known about their tissue distribution, which is particularly important for tissues with high endogenous estrogen and estrogen receptor concentrations. We aimed to investigate the concentrations of genistein, daidzein, and equol in human breast tissue homogenate and to compare these with the corresponding values in serum and urine.

METHODS

A randomized, double-blind, placebo-controlled study was undertaken to evaluate the concentrations of soy-derived phytoestrogens achieved in breast tissue homogenate, serum, and urine after ingestion of either a soy-based food supplement (n = 9) or a placebo tablet (n = 19) for 5 consecutive evenings before aesthetic breast surgery. To account for the heterogeneity of the breast tissue samples, markers for cellularity, epithelial content, blood vessel content, and total fat were determined.

RESULTS

Urine concentrations of genistein, daidzein, and equol were significantly higher in the soy-supplemented subjects than in the subjects ingesting the placebo (P <.05). Only genistein was found to be significantly higher in serum of the soy group than in the placebo group, and no significant differences were found in breast tissue homogenate concentrations of all analytes between the 2 groups.

CONCLUSION

Intake of soy-based food supplements for 5 consecutive days did not result in significantly higher genistein, daidzein, and equol concentrations in breast tissue homogenate when compared with the placebo group. The concentrations were in the low nanomolar range, whereas in the corresponding serum samples, concentrations were a hundred-fold higher.

The role of biological markers as predictors of response to preoperative chemotherapy in large primary breast cancer

The aim of this prospective study was to evaluate biological markers, their correlation with response and outcome, and the change in these markers under the influence of preoperative chemotherapy (PCT) in patients with a large primary breast cancer. One hundred and thirty-five women were treated with PCT, followed by locoregional therapy and adjuvant treatment. Estrogen receptor (ER), progesterone receptor (PgR), HER-2, p53, and cathepsin D were determined by immunohistochemistry (IHC) before and after PCT. The overall response (OR) was 70% and the pathologic complete response (pCR) was 13%. Forty-four percent of the patients could be offered breast-conserving surgery (BCS). At a median follow-up of 50 mo the overall survival is 82% and the disease-free survival is 70%. No local recurrence (LR) has developed following BCS. Invasive ductal carcinoma (IDC) was more frequently ER-negative and HER-2-positive than invasive lobular carcinoma (ILC). P53-negative and ER-negative patients seemed to be more chemosensitive compared to p53-positive patients (74% vs 53%) and ER-positive patients (75% vs 65%), but this difference did not reach statistical significance. A trend toward higher complete pathologic remission rate was seen for ER-negative patients (p = 0.0609). PgR, HER-2, and cathepsin D were not related to response. The pattern of biological markers did not change with PCT, making repeated determination useless.

Better cosmetic results and comparable quality of life after skin-sparing mastectomy and immediate autologous breast reconstruction compared to breast conservative treatment

Preoperative chemotherapy (PCT) can be used in large primary breast cancer to facilitate breast conservative surgery (BCS). Cosmetic results of BCS are influenced by the size of the residual tumour, relative to the size of the breast. After mastectomy, immediate breast reconstruction (IBR) with autologous tissue provides excellent cosmetic outcome and has proven to be safe in breast cancer patients. Besides improving overall and disease free survival, Quality of Life (QoL), body image and cosmetic outcome are also important issues after treatment for breast cancer. In this study, Health-Related-Quality of Life (HRQL) and body image were evaluated, in patients treated with PCT, followed by BCS, or skin-sparing mastectomy (SSM) and perforator-flap breast reconstruction. Additionally, clinical observers assessed cosmetic outcome. All participants were evaluated by the Medical Outcomes Study (MOS) 36-item Short Form Health Status Survey (SF-36, 36 items) and a study-specific questionnaire. An external panel evaluated standardised photographs of the breasts. For all patients, norm-based scores of physical and mental health state are comparable with the general population, except for vitality (VT) score, which is somewhat lower. No significant differences can be observed between both groups. The majority of the patients were satisfied with the appearance of their breasts. The cosmetic results, assessed by the clinical team, were significantly better for patients having IBR, compared to BCS. The mean score was 7.5/10 for IBR, versus 6.0/10 for BCS (p<0.0001).Breast conserving treatment or mastectomy with reconstruction may yield comparable results of QoL, but cosmetic outcome is better after SSM and perforator-flap reconstruction. Patients must be offered both options, and clinicians should stress that both are equally effective.

Different responses to preoperative chemotherapy for invasive lobular and invasive ductal breast carcinoma

AIM

Preoperative chemotherapy (PCT) is used in primary breast cancer, to facilitate breast conservative surgery (BCS). Clinical and pathologic responses are important prognostic parameters. Biologic markers are needed to individualize treatment.

PATIENTS AND METHODS

One hundred and thirty-five patients with breast carcinoma were treated with PCT, followed by surgery and adjuvant therapy. Clinical response and pathological complete response (pCR), biological markers and type of surgery were compared between invasive ductal (IDC) and invasive lobular carcinoma (ILC).

RESULTS

Overall response (OR) for IDC was 75% compared to 50% for ILC (P=0.0151). Pathological CR was 15% for IDC and 0% for ILC (P=0.0066). Fifty-six percent of the responding patients had BCS, in contrast with 16% of the non-responders. BCS was performed in 50% of patients with IDC, in 38% of the patients with ILC. Salvage surgery was more necessary in ILC (19%) compared to IDC (4%) (P=0.0068). Patients with ILC were more frequently ER-positive and HER-2 negative than patients with IDC.

CONCLUSIONS

Clinical and pathological responses are lower in ILC compared to IDC. After PCT, patients with large ILC should preferably be offered mastectomy with immediate breast reconstruction. However, PCT still remains valuable to evaluate tumor response and biologic factors in vivo.

Quantitation of soy-derived phytoestrogens in human breast tissue and biological fluids by high-performance liquid chromatography

A new and reliable HPLC method for the quantitation of daidzein, equol, and genistein in human breast tissue has been developed. The method was applied to biopsies from women undergoing breast reductions, who, prior to surgery, had ingested either a soy isoflavone preparation or a placebo tablet. The results were compared with data collected for urine and serum of the same subjects using standard methods. The limits of detection in the breast tissue homogenate were 24.7 nmol/l for daidzein, 148.0 nmol/l for equol, and 28.4 nmol/l for genistein (S/N of 3). The chromatographic limits of quantitation were 62.5 nmol/l for daidzein and genistein, and 125.0 nmol/l for equol, for which the accuracies were 86.0%, 83.6%, and 81.8%, respectively. The coefficients of variation of these measurements were all below 20% (11.1% for daidzein, 16.4% for genistein, and 13.2% for equol). The sample preparation comprised a concentration step and the absolute limits of quantitation were, therefore, 4.7 nmol/l, 18.8 nmol/l, and 0.94 nmol/l for daidzein and genistein, and 9.4 nmol/l, 37.5 nmol/l, and 1.9 nmol/l for equol in urine, serum, and breast tissue homogenate, respectively. Recoveries were between 70% (+/-5.6%) in breast tissue homogenate and 100% (+/-14.1%) in urine and serum for all three compounds. Equol (less than 1 micromol/l homogenate) was found to be the predominant phytoestrogen in breast tissue and its concentrations exceeded those in serum. The concentrations of phytoestrogens were at least 100-fold higher in urine than in serum and breast tissue.

The citrus methoxyflavone tangeretin affects human cell-cell interactions

Two effects of the citrus methoxyflavone tangeretin on cell-cell interactions are biologically relevant. Firstly, tangeretin upregulates the function of the E-cadherin/catenin complex in human MCF-7/6 breast carcinoma cells. This leads to firm cell-cell adhesion and inhibition of invasion in vitro. Secondly, tangeretin downregulates the interleukin-2 receptor on T-lymphocytes and natural killer cells. This leads to a decrease in the cytotoxic competence of these immunocytes against cancer cells. The second effect can become important when high doses of tangeretin are combined with adjuvant tamoxifen treatment for breast cancer. Experiments with nude mice bearing MCF-7/6 tumors showed that tangeretin given orally at high doses, abrogated the therapeutic suppression of tumor growth exerted by tamoxifen. No evidence for a tumor promoting effect of tangeretin by itself was found in these experiments. Tangeretin may be an interesting molecule for application in cases where immunosuppression could be clinically beneficial.

Inhibition of tamoxifen's therapeutic benefit by tangeretin in mammary cancer

Tangeretin, a molecule present in citrus fruits and in certain 'natural' menopausal medications, is an effective tumour growth and invasion inhibitor in vitro of human MCF 7/6 breast cancer cells. However, when added to the drinking water of MCF 7/6 tumour-bearing mice it neutralises the beneficial tumour-suppressing effect of tamoxifen. Tangeretin reduces the number of natural killer cells. This may explain why the beneficial suppressive effect of tangeretin on MCF 7/6 cell proliferation in vitro is completely counteracted in vivo.

Influence of tangeretin on tamoxifen's therapeutic benefit in mammary cancer

BACKGROUND

Tamoxifen and the citrus flavonoid tangeretin exhibit similar inhibitory effects on the growth and invasive properties of human mammary cancer cells in vitro; furthermore, the two agents have displayed additive effects in vitro. In this study, we examined whether tangeretin would enhance tamoxifen's therapeutic benefit in vivo.

METHODS

Female nude mice (n = 80) were inoculated subcutaneously with human MCF-7/6 mammary adenocarcinoma cells. Groups of 20 mice were treated orally by adding the following substances to their drinking water: tamoxifen (3 x 10(-5) M), tangeretin (1 x 10(-4) M), tamoxifen plus tangeretin (3 x 10(-5) M plus 1 x 10(-4) M), or solvent.

RESULTS AND CONCLUSIONS

Oral treatment of mice with tamoxifen resulted in a statistically significant inhibition of tumor growth compared with solvent treatment (two-sided P = .001). Treatment with tangeretin did not inhibit tumor growth, and addition of this compound to drinking water with tamoxifen completely neutralized tamoxifen's inhibitory effect. The median survival time of tumor-bearing mice treated with tamoxifen plus tangeretin was reduced in comparison with that of mice treated with tamoxifen alone (14 versus 56 weeks; two-sided P = .002). Tangeretin (1 x 10(-6) M or higher) inhibited the cytolytic effect of murine natural killer cells on MCF-7/6 cells in vitro, which may explain why tamoxifen-induced inhibition of tumor growth in mice is abolished when tangeretin is present in drinking water.

IMPLICATIONS

We describe an in vivo model to study potential interference of dietary compounds, such as flavonoids, with tamoxifen, which could lead to reduced efficacy of adjuvant therapy. In our study, the tumor growth-inhibiting effect of oral tamoxifen was reversed upon addition of tangeretin to the diet. Our data argue against excessive consumption of tangeretin-added products and supplements by patients with mammary cancer during tamoxifen treatment.

Changes of intracellular free calcium during intracytoplasmic sperm injection

The present experiments were undertaken to investigate whether the procedure of intracytoplasmic sperm injection (ICSI) is associated with changes in the intracellular free calcium concentration ([Ca2+]i). [Ca2+]i was measured, using the calcium-sensitive dye fura-2, during and after impalement of mouse oocytes with an ICSI pipette and injection of a small amount of medium alone or of medium containing a normal human spermatozoon. Forty-five oocytes were injected with medium. Two different responses were observed: 20 of these cells showed a large increase of [Ca2+]i upon impalement; the other 25 cells did not show any change of [Ca2+]i, neither in the acute period nor in a late period 4 hr after impalement. All the cells that responded with an increase of [Ca2+]i subsequently lysed within the first 30 min following impalement, while all the cells with no [Ca2+]i change remained intact. This observation suggests that only traumatic impalement is associated with an increase of [Ca2+]i. Thirty-one oocytes were successfully, i.e., without subsequent cell lysis, injected with a normal mouse or human spermatozoon. In none of these cells could any acute or late change of [Ca2+]i be observed. The experiments illustrate that successful performance of the ICSI procedure, i.e., ICSI not followed by cell lysis, is not associated with changes of [Ca2+]i in mouse oocytes. This suggests that the ICSI technique, by itself, does not help in activating the oocyte via manipulation-induced changes of [Ca2+]i.

Methods to increase the success rate of artificial insemination with donor semen

Donor insemination was performed in two fertility clinics using cryopreserved semen from the same sperm bank. Donors were selected in agreement with American Fertility Society recommendations. In the first clinic, cup insemination was combined with intra-uterine insemination in 321 cycles. Follicular development was closely monitored with vaginal echography and serum hormonal measurements. In the second clinic, 1287 insemination cycles were performed using intra-cervical insemination, timed only on basal body temperature. In the first clinic, a total of 53 pregnancies were obtained, of which seven were in 55 unstimulated cycles (12.5%), 21 in 159 cycles with clomiphene citrate stimulation (13.1%, P > 0.1), and 25 in 107 cycles stimulated with clomiphene plus human menopausal gonadotrophin (HMG) (23.9%, P < 0.03). No multiple pregnancies were observed in the latter group. In the second clinic, 159 pregnancies occurred during 1287 insemination cycles (12.4%). It is concluded that neither intra-uterine insemination, nor hormonal and echographic cycle monitoring, nor clomiphene citrate enhances the success rate of artificial insemination with donor semen, but HMG treatment probably exerts a favourable effect.

Intracellular pH changes during zona drilling

OBJECTIVE

To investigate whether zona drilling of oocytes, a technique used to locally disrupt the zona pellucida, causes important changes in intracellular pH.

DESIGN AND METHODS

In a first set of experiments, intracellular pH was measured during zona drilling of mouse oocytes, using pH-sensitive microelectrodes. In a second set of experiments human oocytes that failed to fertilize were used to measure intracellular pH during drilling. In these cells intracellular pH was measured using microfluorimetry with the pH-sensitive dye 2',7'-bis-carboxyethyl-5(6)-carboxyfluorescein.

RESULTS

In mouse oocytes intracellular pH dropped from 7.25 +/- 0.02 (mean +/- SEM) to 7.09 +/- 0.03 during zona drilling, followed by a recovery to pH 7.17 +/- 0.02 after 4 minutes (n = 20). In human oocytes, intracellular pH dropped over 0.36 +/- 0.10 pH units during drilling, followed by a recovery that was complete within 4 minutes (n = 14).

CONCLUSION

Zona drilling is associated with a significant cytoplasmic acidification both in mouse and human oocytes. This effect is perhaps related to the high incidence of cytoplasmic degeneration after zona drilling of human oocytes.

Tubal hydatidiform mole

We report a tubal hydatidiform mole, most likely resulting from dispermic fertilization. Early hatching of the embryo, because of a defective zona pellucida, may have favored tubal implantation.

Normal survival and in-vitro development after cryopreservation of zona-drilled embryos in mice

The importance of the zona pellucida on survival after freezing and thawing was investigated. Zona-drilled and zona-intact mouse embryos were fertilized in vitro, cultured to the 2, 4 and 8-cell stages and frozen using conventional methods. Zona drilling did not affect the survival or development of frozen embryos to the blastocyst stage in vitro. We conclude that partial damage to the zona pellucida during micromanipulation procedures is compatible with rates of survival and development which are not different to those observed in zona-intact control embryos.

Experience with zona drilling and zona cutting to improve fertilization rates of human oocytes in vitro

Zona drilling (ZD) and zona cutting (ZC) were used in an IVF programme to assist fertilization in semen defect patients. Twenty-seven patients consented to ZD where acidified Tyrode's was used to create a hole in the zona pellucida. In 19 patients, ZD increased the fertilization rate to 29% compared with 8% (P less than 0.001) in their routine IVF cycles, and in eight patients precluded from routine IVF, a fertilization rate of 14% was achieved. Twenty-two patients consented to ZC where a slit in the zona is made mechanically. In 12 patients ZC increased the fertilization rate to 31% compared with 14% (P less than 0.01) from previous routine IVF cycles, and in 10 patients precluded from routine IVF, a fertilization rate of 34% was achieved. In 13 cycles, 68 uncut control oocytes were inseminated. In five cycles both control and ZC oocytes were fertilized (n.s.d.). In eight cycles no control oocytes were fertilized compared with 27% of ZC oocytes. The polyspermy rate was 4.6%. Twenty-four per cent of ZD and 12% of ZC (P less than 0.01) oocytes and embryos were degenerate after 42 h. Both ZD and ZC can increase the fertilization rate of sub-optimal semen, however, in our hands neither technique produced a pregnancy.

Comparison of zona cutting and zona drilling as techniques for assisted fertilization in the mouse

Zona cutting and zona drilling of the mouse oocyte significantly increased the fertilization rate (3.8-90%) at low sperm concentrations (less than 200,000/ml) compared with zona-intact controls (0-45%). More oocytes were fertilized after zona drilling. Zona cutting was associated with a low loss of oocytes (less than 1%), no increase in polyspermy and normal development in vitro and in vivo after fertilization. There was a 4% oocyte loss rate after zona drilling, mostly due to extrusion of the oocyte from the zona during the procedure. Hatching of blastocysts occurred about 12 h earlier for zona-drilled than for zona-cut and zona-intact control oocytes. Zona drilling was associated with a higher, but not statistically significant, rate of polyspermy at all sperm concentrations tested. The proportion of zygotes developing to the blastocyst stage was not different between the techniques (zona cut, 77%; zona drilled, 66%; control, 71%). Similarly, no difference was found in the percentage of embryos implanting after blastocyst transfer to the uterine horns of pseudopregnant female mice (zona cut, 67%; zona drilled, 68%; control, 77%). Transmission electron microscopy demonstrated the induced defects in the zona with no damage to the oocyte or oolemma. Parthenogenetic activation was not seen after either of the micromanipulative techniques. Both techniques have promise for application to the human.