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PubMed1989

Changes in X-ray sensitivity of mouse eggs from fertilization to the early pronuclear stage, and their repair capacity.

To study the changes in radiosensitivity of male and female genomes from fertilization to the pronuclear stage, the frequency of induced chromosome aberrations was examined at the first-cleavage metaphase in eggs fertilized with X-irradiated sperm, in eggs X-irradiated at the mature oocyte stage immediately before fertilization, and in fertilized eggs exposed to X-rays at various stages before DNA synthesis (1-5 h after insemination). Gametic treatment, fertilization and embryo culture were carried out in vitro. Most of the induced chromosome aberrations were chromosome-type aberrations, the frequency of chromosome fragments being the highest, followed by chromosome exchanges in both sperm and oocytes. The induction of chromosome-type aberrations was much higher in oocytes than in sperm. Chromosome-type aberrations were the main type also in fertilized eggs irradiated at the pre-DNA-synthetic stage. The radiosensitivity increased gradually with pronuclear formation (1-4h after insemination), but little difference in radiosensitivity was observed between eggs irradiated at 4 h and 5 h, corresponding to the stage when pronuclear formation was complete. The drastic change with pronuclear formation was found not only in radiosensitivity but also in the frequency of chromosome aberrations. The frequency of chromosome-type exchanges decreased drastically 2 h after insemination, and exchanges were barely observed at 5 h. The difference in radiosensitivity between male and female genomes also markedly changed with pronuclear formation, the chromosome aberration induction in the female genome being much higher than that in the male genome before accomplishment of pronuclear formation. The analysis of potentiation effects of 3-aminobenzamide and caffeine on the yield of X-ray-induced chromosome aberrations demonstrated that the increase of radiosensitivity and the decrease of chromosome-type exchange induction with pronuclear formation, may be closely correlated with alterations in chromatin configuration in the pronuclei and in repair capacity of fertilized eggs at the pre-DNA-synthetic stage. No evidence based on repair efficiency was found for the marked difference in radiosensitivity between male and female genomes during pronuclear formation.

Animals↗
PubMed2006

Fertility treatment and reproductive health of male offspring: a study of 1,925 young men from the general population.

Little is known the about the reproductive health of offspring after fertility treatment. In 2001-2005, the authors approached young Danish men attending a compulsory physical examination to determine their fitness for military service. A total of 1,925 men volunteered, delivered a semen sample, had a physical examination performed and a blood sample drawn, and responded to a questionnaire. Their mothers were questioned about whether they had received fertility treatment in order to conceive their sons. Forty-seven mothers reported having received fertility treatment to conceive the index subject. After control for confounders, men whose mothers had received fertility treatment to conceive them had a 46% lower sperm concentration (95% confidence interval (CI): -63, -20) and a 45% lower total sperm count (95% CI: -64, -16). They had a smaller testis size (-0.9 ml, 95% CI: -2.2, 0.4), fewer motile sperm (-4.0%, 95% CI: -8.0, -0.1), and fewer morphologically normal spermatozoa (-2.0%, 95% CI: -4.1, 0.0). They also had a lower serum testosterone level and free androgen index (results not statistically significant). These findings should be viewed in light of the increasing use of fertility treatments. Although the cause of these findings is unknown, they raise concern about possible late effects of fertility treatment. Larger-scale studies of children born after fertility treatment should be performed.

Adult↗
PubMed1996

A comparison of baseline and induced DNA damage in human spermatozoa from fertile and infertile men, using a modified comet assay.

Baseline DNA damage in spermatozoa from fertile and infertile men was compared using a modified alkali single cell gel electrophoresis (comet) assay. Semen from normozoospermic fertile, normozoospermic infertile and asthenozoospermic infertile (World Health Organization criteria, 1992) samples were studied. No significant difference was observed in levels of baseline damage between the three groups. A median value for baseline damage of approximately 20% (80% head DNA) was obtained in all samples. Irradiation with X-rays (5-30 Gy) produced no additional damage in fertile samples when median values were examined. However, irradiation with 30 Gy X-rays produced significant damage in both infertile groups. Hydrogen peroxide (40 microM) treatment induced significant damage in the asthenozoospermic group, whereas 100 microM H2O2 was required to cause significant damage in the normozoospermic fertile and infertile samples. Within the fertile population a subgroup in which percentage head DNA was greater than 80% was observed in both treated and untreated specimens. This subgroup significantly decreased with treatment in both infertile groups. We conclude that the asthenozoospermic infertile group is more susceptible to damage than the normozoospermic infertile group, which in turn is more susceptible than the fertile group. The fertile group contains a resistant subpopulation of spermatozoa with relatively intact DNA.

DNA↗
PubMed1998

Multiple deletions of mitochondrial DNA are associated with the decline of motility and fertility of human spermatozoa.

Sperm motility is one of the major determinants of male fertility and is required for successful fertilization. In a previous study, we demonstrated that the occurrence and accumulation of the 4977 bp deletion of mitochondrial DNA (mtDNA) is associated with diminished fertility and motility of human spermatozoa. The possible relationship between multiple deletions of mtDNA and the decline of fertility and motility in human spermatozoa was further explored in 36 subjects including subfertile and infertile males in this study. Using long-range polymerase chain reaction (PCR), we confirmed the 4977 bp deletion and identified two novel deletions of 7345 and 7599 bp of mtDNA in the spermatozoa with poor motility. We used Percoll gradients to fractionate spermatozoa with differing motility, and then screened for two novel large-scale deletions of the mtDNA. The results showed that the ratio of the deleted mtDNA in the spermatozoa with poor motility and diminished fertility were significantly higher than those in the spermatozoa with good motility and fertility. In addition, we found that the frequencies of the three large-scale deletions in the spermatozoa from patients with primary infertility and oligoasthenozoospermia were higher than those of the fertile males. Our findings suggest that mtDNA deletions may play an important role in some pathophysiological conditions of human spermatozoa.

Base Sequence↗
PubMed2004

Growth response and sapwood hydraulic properties of young lodgepole pine following repeated fertilization.

We examined how tree growth and hydraulic properties of branches and boles are influenced by periodic (about 6 years) and annual fertilization in two juvenile lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands in the interior of British Columbia, Canada. Mean basal area (BA), diameter at breast height (DBH) and height increments and percent earlywood and sapwood hydraulic parameters of branches and boles were measured 7 or 8 years after the initial treatments at Sheridan Creek and Kenneth Creek. At Sheridan Creek, fertilization significantly increased BA and DBH increments, but had no effect on height increment. At Kenneth Creek, fertilization increased BA, but fertilized trees had significantly lower height increments than control trees. Sapwood permeability was greater in lower branches of repeatedly fertilized trees than in those of control trees. Sapwood permeabilities of the lower branches of trees in the control, periodic and annual treatments were 0.24 x 10(-12), 0.35 x 10(-12) and 0.45 x 10(-12) m2 at Kenneth Creek; and 0.41 x 10(-12), 0.54 x 10(-12) and 0.65 x 10(-12) m2 at Sheridan Creek, respectively. Annual fertilization tended to increase leaf specific conductivities and Huber values of the lower branches of trees at both study sites. We conclude that, in trees fertilized annually, the higher flow capacity of lower branches may reduce the availability of water to support annual growth of the leader and upper branches.

Pinus↗
PubMed2005

Carbon budget for Scots pine trees: effects of size, competition and site fertility on growth allocation and production.

Time series of carbon fluxes in individual Scots pine (Pinus sylvestris L.) trees were constructed based on biomass measurements and information about component-specific turnover and respiration rates. Foliage, branch, stem sapwood, heartwood and bark components of aboveground biomass were measured in 117 trees sampled from 17 stands varying in age, density and site fertility. A subsample of 32 trees was measured for belowground biomass excluding fine roots. Biomass of fine roots was estimated from the results of an earlier study. Statistical models were constructed to predict dry mass (DW) of components from tree height and basal area, and time derivatives of these models were used to estimate biomass increments from height growth and basal area growth. Biomass growth (G) was estimated by adding estimated biomass turnover rates to increments, and gross photosynthetic production (P) was estimated by adding estimated component respiration rates to growth. The method, which predicts the time course of G, P and biomass increment in individual trees as functions of height growth and basal area growth, was applied to eight example trees representing different dominance positions and site fertilities. Estimated G and P of the example trees varied with competition, site fertility and tree height, reaching maximum values of 22 and 43 kg(DW) year(-1), respectively. The site types did not show marked differences in productivity of trees of the same height, although height growth was greater on the fertile site. The G:P ratio decreased with tree height from 65 to 45%. Growth allocation to needles and branches increased with increasing dominance, whereas growth allocation to the stem decreased. Growth allocation to branches decreased and growth allocation to coarse roots increased with increasing tree size. Trees at the poor site allocated 49% more to fine roots than trees at the fertile site. The belowground parts accounted for 25 to 55% of annual G, increasing with tree size and decreasing with site fertility. Annual G and P per unit needle mass varied over the ranges 1.9-2.4 and 3.5-4.0 kg(DW) kg(-1), respectively. The relationship between P and needle mass in the example trees was linear and relatively independent of competition, site fertility and age.

Biomass↗
PubMed1988

Boron fertilization and carbohydrate relations in mycorrhizal and nonmycorrhizal shortleaf pine.

Eight-week-old shortleaf pine seedlings (Pinus echinata Mill.) with and without ectomycorrhizae formed by Pisolithus tinctorius were treated for two to eight weeks with 25 microg borate ml(-1) solution applied either to the soil, or as a foliar spray, or in both ways. Control seedlings were fertilized only with modified Hoagland's solution containing 0.03 microg ml(-1) borate. Five sugars (pinitol, fructose, glucose, myoinositol and sucrose) were quantitated in both mycorrhizal and nonmycorrhizal roots by gas-liquid chromatography. Fertilization with boron increased the total carbohydrate content of mycorrhizal roots except in seedlings receiving foliar applications of boron. Foliar + soil fertilization yielded a 24% increase in total carbohydrates in mycorrhizal roots, whereas foliar fertilization alone decreased the total carbohydrate content. Carbohydrate content of nonmycorrhizal roots was significantly increased only by soil fertilization with boron. Individual sugars were affected less by boron fertilization in nonmycorrhizal roots than in ectomycorrhizal roots. However, significant increases in sugars in response to boron fertilization were observed in both ectomycorrhizal and nonmycorrhizal plants.

Journal Article↗
PubMed1986

Fertilized and unfertilized ova are transported at different rates by the hamster oviduct.

To determine if the egg provides any clues for the regulation of ovum transport in the hamster, oocyte and embryo transport were compared. On the evening preceding ovulation, the animals were randomly assigned to one of five groups. They were caged overnight with a male of proven fertility (Group 1) or they were isolated (Group 2). Other females were artificially inseminated in both uterine horns at 2200 h either with fertile epididymal spermatozoa (Group 3), spermatozoa rendered infertile by freezing and thawing (Group 4), or with fertile spermatozoa in one uterine horn and infertile spermatozoa in the contralateral horn (Group 5). The number, condition, and distribution of ova in the genital tract were assessed at various intervals during the next 4 days. The rate of fertilization and normal development in females or sides inseminated with fertile or infertile spermatozoa was over 90% and 0% respectively. Embryos in Groups 1 and 3 reached the uterus 1 day earlier than unfertilized oocytes in Groups 2 and 4. In group 5, the transport of embryos resulting from insemination with fertile spermatozoa followed a pattern similar to those in Groups 1 and 3; the oocytes in the contralateral tract resembled those of Groups 2 and 4. The different transport rates of embryos and oocytes were not associated with the reproductive state of the female but with the condition of the ova. Moreover, the different transport rates were observed in animals transporting the two types of eggs simultaneously on different sides indicating that there is a local recognition of some unidentified factor unequally present in fertilized and unfertilized eggs.

Animals↗
PubMed1985

Proteolytic activity in anther extracts of fertile and cytoplasmic male sterile petunia.

Proteolytic activity is compared in anther extracts from Petunia parodii fertile and cytoplasmic male sterile lines. It is characterized relative to developmental stage of the anthers, effect of variable incubation times, pH of isolation buffers, and degradation of marker proteins. In fertile anthers, proteolytic activity increases at the end of microsporogenesis and peaks early in microgametogenesis. Degradation is most severe in extracts of fertile anthers and in high molecular weight proteins and reaches its maximum within 20 minutes. Degradation of marker proteins is greatest at pH 5.6 to 8.0 in fertile anther extracts and is eliminated under strong acid conditions (pH 2.8 to 4.0) in both fertile and cytoplasmic male sterile anther extracts. Marker proteins degrade more severely in extracts of fertile anthers; however, the order of substrate sensitivity-myosin > phosphorylase b > bovine serum albumin and ovalbumin > beta-galactosidase-is the same in extracts from fertile and cytoplasmic male sterile anthers.

Journal Article↗
PubMed2001

Return of fertility in nulliparous women after discontinuation of the intrauterine device: comparison with women discontinuing other methods of contraception.

OBJECTIVE: To clarify the effect of the using the intrauterine device on fertility in nulliparous women. DESIGN: Prospective cohort study of two groups of nulliparous women, one recruited while using an intrauterine device and the other while using an oral contraceptive. SETTING: Seventeen family planning clinics in England and Scotland. SAMPLE: 1,071 nulliparous, married women, aged 18-40 years, 558 of whom contributed information to the main objective of the study. METHODS: The women were recruited between 1982 and 1985 and followed up annually to 1994. Dates and reasons for any contraceptive method changes (which were most frequently to barrier methods) were recorded, together with the outcome of any pregnancies, at each follow up. MAIN OUTCOME MEASURES: The number of nulliparous women giving birth at term after stopping contraception (oral contraceptive, intrauterine device or barrier method) in order to conceive. RESULTS: Women who stopped using a barrier method to achieve a planned pregnancy conceived most quickly: 54% were delivered after one year vs 39% of intrauterine device and 32% of oral contraceptive users (log rank P = 0.002). There was no association between fertility and duration of oral contraceptive use: However, short term intrauterine device users (< 42 months) showed a fertility pattern more favourable than seen in those discontinuing oral contraceptives, with increasing duration of intrauterine device use being associated with decreasing fertility (linear trend P = 0.005); the fertility of women who had used the intrauterine device for 78 + months was the most impaired (28% were delivered by 12 months vs 46% of short term users; at 36 months the corresponding figures were 79% vs 91%). This association remained after adjusting for potential confounding factors, including maternal age, husband's social class, and history of gynaecological illnesses, factors which themselves had independent associations with fertility. CONCLUSIONS: Long term intrauterine device use in nulliparous women appears to be associated with an increased risk of fertility impairment.

Adolescent↗
PubMed2006

Caesarean section and subsequent fertility in sub-Saharan Africa.

OBJECTIVE: To determine the impact of caesarean section on fertility among women in sub-Saharan Africa. DESIGN: Analysis of standardised cross-sectional surveys (Demographic and Health Surveys). SETTING: Twenty-two countries in sub-Saharan Africa, 1993-2003. SAMPLE: A total of 35 398 women of childbearing age (15-49 years). METHODS: Time to subsequent pregnancy was compared by mode of delivery using Cox proportional hazards regression models. MAIN OUTCOME MEASURES: Natural fertility rates subsequent to delivery by caesarean section compared with natural fertility rates subsequent to vaginal delivery. RESULTS: The natural fertility rate subsequent to delivery by caesarean section was 17% lower than the natural fertility rate subsequent to vaginal delivery (hazard ratio = 0.83, 95% CI 0.73-0.96, P < 0.01; controlling for age, parity, level of education, urban/rural residence and young age at first intercourse). Caesarean section was also associated with prior fertility and desire for further children: among multiparous women, an interval > or =3 versus <3 years between the index birth and the previous birth was associated with higher odds of caesarean section at the index birth (OR = 1.4, 95% CI 1.1-1.7, P= 0.005); among all women, the odds of desiring further children were lower among women who had previously delivered by caesarean section (OR = 0.67, 95% CI 0.54-0.84, P < 0.001). Caesarean section did not appear to increase the risk of a subsequent pregnancy ending in miscarriage, abortion or stillbirth. CONCLUSIONS: Among women in sub-Saharan Africa, caesarean section is associated with lower subsequent natural fertility. Although this reflects findings from developed countries, the roles of pathological and psychological factors may be quite different because a much higher proportion of caesarean sections in sub-Saharan Africa are emergency procedures for maternal indication.

Adolescent↗
PubMed1996

Ectopic pregnancy loss during fertility management.

Using qualitative techniques, data were obtained from seven women who experienced an ectopic pregnancy loss while undergoing fertility management. Ectopic pregnancy is a risk factor associated with fertility management, but unlike early miscarriage in fertility management, an ectopic pregnancy has additional potential negative sequelae for the women, including risk for severe hemorrhage and death and threat to future fertility. The purpose of this study was to describe women's experiences of loss following diagnosis and treatment of an ectopic pregnancy while undergoing fertility management. A thematic analysis of the data derived from semistructured interviews was conducted. Themes emerging from the women's discussion of their pregnancy loss and fertility plans included physical pain and shutdown, emotional protection, grief, and pressure, endpoints, and decision making. For women continuing fertility management, both the life-threatening risks of future ectopics and time allowances for grieving were minimized.

Abortion, Spontaneous↗
PubMed1995

Nuclei from fertilized mouse embryos have calcium-releasing activity.

During mammalian fertilization, the sperm triggers a series of intracellular Ca2+ oscillations which initiate oocyte activation and the formation of pronuclei. Oocyte activation can be induced artificially by a variety of chemical and physical stimuli which elevate intracellular calcium. We show that the transfer of nuclei from 1- and 2-cell-stage fertilized mouse embryos to unfertilized oocytes stimulates the completion of meiosis and the formation of pronuclei. Nuclei from embryos that had developed to the 4-cell stage did not stimulate meiotic resumption. The ability to cause oocyte activation was specific to nuclei transferred from fertilized embryos as nuclei from parthenogenetic embryos or cytoplasts from fertilized or parthenogenetic embryos did not induce activation. Nucleus-induced oocyte activation was associated with the generation of intracellular Ca2+ transients, which were seen after nuclear envelope breakdown of the transferred nuclei. Treatment of the oocyte with the intracellular Ca2+ chelator, BAPTA, prior to nuclear transfer inhibited intracellular Ca2+ transients and oocyte activation. The specific Ca(2+)-releasing activity of the nucleus was not caused by sperm-induced protein synthesis since similar activity was present in nuclei originating from embryos exposed to cycloheximide throughout fertilization. The specific ability of nuclei from fertilized embryos to stimulate Ca2+ transients and oocyte activation was also found in nuclei from embryos parthenogenetically activated by the injection of a partially purified cytosolic sperm factor. The results suggest that the fertilizing sperm introduces Ca(2+)-releasing activity which becomes associated with the nucleus of early mammalian embryos.

Animals↗
PubMed1994

Nuclear distribution of proliferating cell nuclear antigen (PCNA) in fertilized eggs of the starfish Asterina pectinifera.

Previous studies (Nomura et al. (1991) Dev. Biol. 143, 289-296 (1993) Dev. Biol. 159, 288-297) determined the time of DNA replication period (S phase) in starfish eggs fertilized either during or after oocyte maturation. Here proliferating cell nuclear antigen (PCNA) localized within nuclei of starfish eggs was detected with an anti-PCNA human antiserum. Using a confocal laser scanning microscope, a three-dimensional structure of the PCNA region was analyzed. In eggs fertilized during maturation, PCNA started to localize within the nuclei at the same time as the initiation of the first S phase. During the S phase, the distribution of localized PCNA in a three-dimensional view coincided with the chromatin distribution. After the S phase, PCNA remained localized within the nuclei, but its distribution no longer coincided with the chromatin distribution. In eggs fertilized after maturation, however, PCNA started to localize within the female pronuclei about 10 minutes ahead of the first S phase. Localized PCNA occupied only a limited region of the nuclei without diffusing over the whole nuclear area. Chromatin distributed around the peripheral region of the nuclei mostly outside the PCNA region. When the first S phase was initiated, the chromatin distribution became coincident with the PCNA region. Later behavior of PCNA was the same as that of the eggs fertilized during maturation. The precocious localization of PCNA in those eggs fertilized after maturation simply demonstrates that the 'postactivation process' for preparing DNA replication is triggered by fertilization and PCNA localization and S phase are sequentially initiated with a time-lapse. On the other hand, the simultaneous occurrence of them seen in those eggs fertilized during maturation indicates that the postactivation process must be going on in parallel with the maturation process.

Adenine↗
PubMed2002

[Correlation between polyspermy and the outcome of in vitro fertilization-embryo transfer]

OBJECTIVE: To explore the influence of polyspermy on IVF outcomes in in vitro fertilization and embryo transfer(IVF-ET). METHODS: The data from 496 IVF-ET cycles and 5349 oocytes were analyzed retrospectively. A comparison of a number of fertility parameters with and without polyspermy was done. The fertility parameters were the number of oocytes retrieved, percentage of mature oocytes, fertilization rate, cleavage rate, occytes for ET, pregnancy rate. RESULTS: The percentage of mature occytes, fertilization rate, cleavage rate was 67.0 %,76.7 %and 95.6 %, respectively( P< 0.01). The pregnancy rate was higher in polyspermic fertilization cycles (25.7 %) than in cycles without polyspermy(23.6 %),but with no statistical significance ( P>0.05). CONCLUSION: Polyspermic fertilization is correlated with improved oocyte receptibility to sperm and could be considered as an encouraging sign for the success of IVF.

Journal Article↗
PubMed1992

A simple measure of fertility control.

We describe a simple measure of fertility control: the proportion of all births from the age-specific fertility schedule that occurs among women by age 35. This measure has broad applicability because it does not require information on marital fertility rates. When both the proportion of births by age 35 and the most commonly used measure of fertility control, m, are calculated for a population over time, they are correlated very highly. Because of increasing levels of nonmarital fertility in several developed countries, measures of fertility control that are based on marital fertility are less appropriate now than in the past.

Adult↗
PubMed1987

Fertility issues in the therapy of nonseminomatous testicular tumors.

Given the data described herein, there is reason for even greater optimism about the possibility of fertility among patients with testicular cancer. Fertility issues have been and will continue to be important as different therapies for nonseminomatous cancer are proposed. For example, we previously calculated that the difference in fertility between patients who are treated with expectant therapy versus lymph-adenectomy for clinical stage I disease was only 16 patients in favor of expectant therapy. If new data on relapse rates after expectant therapy (e.g., 30 per cent) and better ejaculation preservation rates after lymphadenectomy (e.g., 85 per cent) are incorporated into this calculation, the number benefited falls to 6 patients. It has also been proposed that patients with low-volume stage IIB disease should receive initial chemotherapy and that lymphadenectomy should be reserved for those patients with residual disease. Applying these calculations along with certain additional assumptions, the difference in fertility between these two treatment alternatives is only 4 patients in favor of initial chemotherapy (P.H. Lange; manuscript in preparation). However, this approach has significantly greater toxicity. Much more must be done to improve our understanding and management of infertility in patients with testicular cancer. Additional tasks include the need to establish the exact ratio of patients with testicular cancer who have infertility that precedes or is a result of their disease, and to develop methods for predicting fertility status so that treatment can be tailored accordingly. Also, we must consolidate and improve the indications, techniques, and results for fertility-sparing lymphadenectomy in ways that have been described herein. In addition, the exact damage-to-benefit ratio for the number of courses and types of chemotherapy administered to patients will need to be studied carefully and prospectively, preferably in cooperative groups. The accelerating advances in in vitro fertilization and cryopreservation must be watched carefully, and their application to appropriate patients with nonseminomatous cancer should be encouraged. Cryopreservation before therapy should continue to be advocated. All of these tasks are extremely difficult because they require precise analysis of carefully generated statistics and difficult judgments about individual human values.

Humans↗
PubMed1997

Activation of protein kinase C after fertilization is required for remodeling the mouse egg into the zygote.

Fertilization of the mammalian egg initiates numerous biochemical and structural changes which remodel the egg into a single-celled zygote. To date, the most extensively studied phenomenon of fertilization in virtually all species has been the relationship between sperm penetration and the induction of the initial rise in intracellular-free calcium ([Ca2+]i) concentration within the egg. In contrast, relatively few studies have focused on the biochemical events following this rise in calcium, and even fewer studies have directly linked the biochemical events to the structural changes which must ensue for proper development of the embryo. In this study, we exploited recently developed technologies to investigate the action of protein kinase C (PKC), a presumed downstream transducer of the initial rise in [Ca2+]i, during fertilization and artificial activation with calcium ionophore or phorbol 12-myristate 13-acetate (PMA). The newly developed myristoylated PKC pseudosubstrate (myrPKC psi) was used to specifically inhibit PKC, thereby averting the trauma of injecting the egg with nonmyristoylated PKC psi. Following fertilization, eggs which were pretreated with myr-PKC psi were not capable of forming a second polar body and pronuclear formation was significantly inhibited. Spatial and temporal localization of PKC using confocal microscopy to visualize the PKC reporter dye, Rim-1, demonstrated localization of PKC to the lateral aspects of the forming second polar body after fertilization, or after artificial activation with calcium ionophore or PMA. In vivo biochemical analysis of eggs which were fertilized or artificially activated demonstrated that PKC activity rose at the same time (40 min) as the second polar body formed and then subsided over the next 5 hr post activation. From these data, we conclude that PKC plays an integral role in directing the transformation from egg to embryo.

Animals↗