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PubMed1998

Embryonic development as a quasi-historical process.

This essay explores the nature of embryonic development in contrast to other kinds of processes. Anhistorical processes are highly reproducible and are therefore subject to standard scientific analysis. Such analyses yield results that may well apply universally. Euhistorical processes are non-reproducible. Therefore they are not subject to standard scientific analysis, but are investigated primarily by retrospective speculation. Information gained from such analyses is of relatively limited applicability. Embryonic development exhibits traits associated with both anhistorical and euhistorical processes and is therefore defined as a quasi-historical process. The quasi-historical nature of developmental processes places constraints on the nature of the solution we can hope to obtain for the problem of development, but also provides a means of exploring the euhistorical process of evolution.

Animals↗
PubMed1993

Hypoxanthine phosphoribosyltransferase activity in bovine embryos during the early embryonic development.

The activity of hypoxanthine phosphoribosyltransferase (HPRT) was determined in the bovine embryo during early embryonic development. Microassay, using [(3)H] hypoxanthine, was improved to measure enzyme activity in the embryonic extract. This activity depended on the reaction time and the concentration of phosphorybosyl pyrophosphate (PRPP) in a reaction. mixture. Maximum activity was obtained at 4 hours of reaction time and at a concentration of 1 mM PRPP, but was much lower than the activity recorded in the mouse embryo. During early embryonic development, HPRT activity rapidly increased beyond the 8-cell stage. When distributions and activities of HPRT, adenine phosphorybosyltransferase (APRT), and the ratio of HPRT: APRT were examined in individual blastocysts, HPRT activity was broadly distributed, but it did not clearly show the bimodal distribution expected. Six of demi-embryos with high or low HPRT:APRT ratios were transferred to recipient cows from which 2 calves were obtained. Both offspring were of the sex predicted by the HPRT: APRT ratio. These results indicate that HPRT activity of bovine preimplantation embryos can be microassayed using radiolabeled hypoxanthine, and this assay could provide an alternative method for embryo sexing.

Journal Article↗
PubMed2004

Insulin-like growth factor binding protein 1 and human embryonic development during 6 - 10 gestational weeks.

BACKGROUND: Insulin-like growth factor binding protein-1 (IGFBP-1), which is a carrier of Insulin-like growth factors (IGFs) regulates the fetal development by working as an active factor controlling the combination of IGFs with their receptors. This study was designed to investigate the relationship between IGFBP-1 and human embryonic development during weeks 6 - 10 of gestation. METHODS: A total of 44 pregnant women with singleton pregnancy were divided into two groups: one with abnormal embryo development (n = 32) and the other with normal embryo development (n = 12). Enzyme-linked immunosorbent assay (ELISA) was employed to detect IGFBP-1 levels in maternal serum and decidual tissue. The expression of IGFBP-1 mRNA in deciduas was examined by reverse transcription polymerase chain reaction (RT-PCR) technique. RESULTS: The level of IGFBP-1 protein in maternal serum was significantly higher in the abnormal group [(125.36 +/- 47.93) micro g/ml] than in the normal group [(70.72 +/- 21.21) micro g/ml]. Both of IGFBP-1 and IGFBP-1 mRNA in deciduas were higher in abnormal group [(1.60 +/- 1.39) micro g/ml and 1.66 +/- 1.64, respectively] than in the normal group [(0.35 +/- 0.23) micro g/ml and 0.40 +/- 0.20, respectively]. The level of IGFBP-1 in maternal serum was positively correlated with IGFBP-1 mRNA (r = 0.90, P < 0.05) and IGFBP-1 protein (r = 0.92, P < 0.05) in decidual tissue. CONCLUSIONS: During weeks 6 - 10 of gestation, abnormal embryonic development is correlated with elevated IGFBP-1. The level of IGFBP-1 in maternal serum is related to the concentrations of IGFBP-1 mRNA and IGFBP-1 in decidual tissue. The IGFBP-1 level in maternal serum may be used as a predictive marker to evaluate embryonic development.

Adult↗
PubMed2005

[Formation of striatum structural and ultrastructural organization in the early postnatal ontogenesis of rats subjected to altered conditions of their embryonic development].

Formation of the structure of striatum during two postnatal weeks in rats subjected to acute hypoxia during various periods of their embryonic development was studied using light microscopic (Nissl's stain and Golgi's silver nitrate impregnation) methods and electron microscopy. This study was supplemented by a simultaneous investigation of physiological development of the same population of rats. The data obtained demonstrated that prenatal hypoxia on day 13.5 of embryonic development (E13.5) led to a delayed neurogenesis (retardation in the development of neuropil elements and cell differentiation) as well as to the malformation of the structure of striatum (degeneration, in particular, chromatolysis of neurons and glial nodule formation). Morphometric analysis demonstrated that prenatal hypoxia on E13.5 resulted in a statistically significant decrease in cell number in the striatum, these changes being especially pronounced in large neurons. Prenatal hypoxia on E18.5, however, caused no significant changes in striatum. Structural changes in the striatum were shown to be accompanied by significant changes in the physiological development of animals. The data obtained demonstrated that the alteration of the conditions of embryogenesis (hypoxia) during the period of most intensive proliferation of forebrain neuroblasts resulted in the disturbances of the formation of both striatum nervous tissue of the organism as a whole during early postnatal ontogenesis.

Animals↗
PubMed2006

Normal embryonic development of the Japanese pipistrelle, Pipistrellus abramus.

The normal embryonic development of the Japanese pipistrelle, Pipistrellus abramus was described. A total of 13 stages between the early pharyngula and the embryo just before birth were established, based on external morphological features of 33 embryonic specimens. To aid embryological comparison between chiropteran lineages, the stage numbers used in the Carollia perspicillata embryonic staging system (Cretekos et al., 2005) were applied to each embryonic stage of P. abramus. The size (crown-rump length, CRL) of P. abramus embryos became larger throughout ontogeny at a relatively constant rate. When the CRL of embryos was compared in each morphologically corresponding embryonic stage, the CRL of P. abramus was always smaller than that of C. perspicillata. The overall nature of organogenesis was almost similar in both P. abramus and C. perspicillata. Species-specific differences in bats were observed at later stages of embryogenesis, notably in the craniofacial and tail regions.

Animals↗
PubMed1999

Expression of LKB1 and PTEN tumor suppressor genes during mouse embryonic development.

Germ-line mutations of LKB1 and PTEN tumor suppressor genes underlie the phenotypically related Peutz-Jeghers syndrome (PJS) and Cowden disease (CD), respectively. To analyze possible developmental roles of PTEN and LKB1, we have studied their mRNA expression during mouse embryonic development (E7-17.5) by in situ hybridization. Ubiquitous expression of both genes during early stages (E7-11) became more restricted in later embryonic development (E15-19) where LKB1 and PTEN showed prominent overlapping expression in e.g. gastrointestinal tract and lung. In contrast, LKB1 was selectively expressed at high levels in testis and PTEN was prominently expressed in skin epithelium and underlying mesenchyme. These results indicate that LKB1 and PTEN display largely overlapping expression patterns during embryonic development. Moreover, a high expression of these genes was observed in the tissues and organs affected in PJS and CD patients and in PTEN+/- mice.

AMP-Activated Protein Kinases↗
PubMed2004

The effect of oxygen tension on porcine embryonic development is dependent on embryo type.

Reducing oxygen concentration from atmospheric levels during in vitro culture generally, but not invariably, improves embryonic development across a range of species. Since the few published reports of such an action in the pig are contradictory--perhaps a consequence of the derivation of the embryos prior to culture--a study was performed to examine the effect of O2 tension during culture on three different types of porcine embryos, namely: in vivo flushed embryos, and in vitro matured oocytes either fertilized in vitro or parthenogenetically activated. In vivo embryos (n=208) were flushed at the 2-8 cell stage. Cumulus oocyte complexes (COCs) destined for IVF or parthenogenetic activation were derived from 2 to 6 mm, post-pubertal ovarian follicles and matured for 48 h in TCM-199. Parthenogenones were generated by activating denuded oocytes (n=573) with 10 mM calcium ionophore, followed by 2 mM DMAP prior to culture. The IVF embryos (n=971) were produced by fertilizing COCs (day 0) with fresh ejaculated semen in modified tris-based medium for 6 h before cumulus removal. All embryos were cultured in BECM-3 containing 12 mg/mL fatty-acid-free BSA up to day 4, followed by BECM-3 supplemented with 10% calf serum until day 7. The gas environment for IVM/IVF was 5% CO2 in air, while that for IVC was either 5% CO2 in air or 5% O2, 5% CO2 and 90% N2. Low O2 tension increased both day 7 blastocyst rates (high versus low O2, respectively; 9.3+/-2.9%: 26/280; 23.9+/-4.2%: 71/293; P<0.001) and total cell numbers (39.3+/-2.9, n=24 versus 61.2+/-7.7, n=61; P=0.01) of parthenogenetically activated embryos. In contrast, such a treatment neither affected blastocyst rates (89.3+/-6.9 versus 87.8+/-7.5) nor cell numbers (87.4+/-4.5 versus 87.7+/-4.8) of in vivo flushed embryos. The effect of reduced O2 concentration on IVF embryos was intermediate, since only cell numbers were improved (69.8+/-3.5, range=17-204, n=49; 88.5+/-5.8, range=28-216; n=66; P<0.01), equivalent to that recorded in in vivo flushed embryos. However, blastocyst rates were unaffected (10.7+/-1.4%: 51/486; 12.9+/-2.2%: 67/485). The effect, when present, of reducing O2 concentration from 20 to 5% was beneficial for pig in vitro embryonic development. The responses are apparently dependent on firstly, the manner by which the embryonic cell cycle is activated and secondly, the derivation of the tissue prior to placement into culture, if the observed resilience of in vivo embryos is independent of treatment duration.

Animals↗
PubMed2005

Possible effect of 30K proteins in embryonic development of silkworm Bombyx mori.

The silkworm Bombyx mori possesses a 30K protein family of 3x10(4) Da, the biological functions of which have not been fully identified. The relationship between the 30K protein family and the embryonic development of temperature sensitive sex-linked mutant strain of silkworm was investigated by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The results show that protein spots 1-5 of the 30K protein family, mainly existing in normal strain, are possibly related to embryonic development. The early consumption of a 30K protein named 6G1-30K-1 and the accumulation of 30K proteins named 6G1-30K-3 and 6G1-30K-4 are likely caused by the destruction of physiological balance in normal embryonic development, which may lead to lower hatchability of the temperature sensitive strain. The results suggest that reasonable metabolism of 30K proteins is a prerequisite for the embryo's normal development.

Animals↗
PubMed1992

Relationship of hen age and egg sequence position with fertility, hatchability, viability, and preincubation embryonic development in broiler breeders.

Indian River broiler breeder hens (n = 29) were caged individually to investigate whether hen age and egg sequence position were related significantly to the dependent variables fertility, hatchability, viability (hatch of fertile eggs), and preincubation embryonic development. Hens were artificially inseminated once per week. All eggs laid during the period of 31 to 54 wk of age were stored at 16 to 17 C for .5 to 7 days. Time of oviposition records were used to assign eggs to sequence position ("first" or "subsequent"). Eggs laid on odd-numbered weeks were broken open, fertility determined, and embryonic development staged. Eggs laid on even-numbered weeks were sent to a commercial hatchery to assess hatchability. Unhatched eggs were opened to determine fertility and embryonic mortality. In addition, hen weight, number of days since insemination, time of oviposition, and egg weight were recorded to determine their relationship to the dependent variables. Fertility (n = 3,240 eggs) and hatchability (n = 1,653 eggs) were not significantly related to egg sequence position, but were related to hen age (P = .0001 and P = .0002, respectively). Older hens demonstrated lower fertility and hatchability. In contrast, embryo viability (n = 1,487 eggs) and preincubation embryonic development (n = 1,200 eggs) were not significantly related to hen age, but were related to egg sequence position (P = .0026 and P = .0001, respectively). First-of-sequence eggs had lower viability, and embryos of these eggs were more developed than embryos of subsequent eggs. These data indicate that the reduction in chick production observed as the hen ages may be due to the increased incidence of first-of-sequence eggs.

Aging↗
PubMed2001

Tet-system for the regulation of gene expression during embryonic development.

The ability to control gene expression in a temporal and spatial manner provides a new tool for the study of mammalian gene function particularly during development and oncogenesis. In this study the suitability of the tet-system for investigating embryogenesis was tested in detail. The tTACMV(M1) and rTACMV-3 (reverse Tc-controlled transactivator) transgenic mice were bred with NZL-2 bi-reporter mice containing the vector with a tTA/rTA responsive bidirectional promoter that allows simultaneous regulation of expression of two reporter genes encoding luciferase and beta-galactosidase. In both cases reporter genes were found to be expressed in a wide spectrum of tissues of double transgenic embryos and adult mice. The earliest expression was detected in tTACMV(M1)/NZL-2 embryos at embryonic day 10.5 (E10.5) and rTACMV-3/NZL-2 embryos at E13.5. Doxycycline abolished beta-gal expression in tTACMV(M1)/NZL-2 but induced it in rTACMV-3/NZL-2 embryos including late stages of embryo-genesis. The tTA and rtTA transactivators thus revealed a partially complementary mode of action during second half of embryonic development. These experiments demonstrated that both Tet regulatory systems function during embryonic development. We conclude that the Tet systems allows regulation of gene expression during embryonic development and that 'double reporter' animals like the NZL-2 mice are useful tools for the characterization of newly generated tet transactivator lines expressing tTA (or rtTA) in embryonic as well as in adult tissues.

Aging↗
PubMed1979

Ultrastructural study of the embryonic development of the pineal gland of the chicken (Gallus gallus).

The authors studied the embryonic development of the pineal gland of the chicken with the electron microscope. The denomination of 'pinealoblasts' was given to the undifferentiated cells which form the primitive pineal outline. In the wall of the pineal cavities, the follicular and parafollicular zones were distinguished; these are formed by type A and type B pinealocytes, the B type being much more abundant. The degenerated cells are constant in the pineal throughout its embryonic development, but much more abundant in the early phases.

Animals↗
PubMed2025

FTDC1/2, oocyte-specific cofactors of DNMT1 required for epigenetic regulation and embryonic development.

The unique epigenetic patterns during gametogenesis and embryonic development indicate the existence of specialized methylation machinery. In the present study, we describe the discovery of two oocyte-specific cofactors of DNA methyltransferase 1 (DNMT1), encoded by uncharacterized genes, ferritin domain containing 1 and 2 (Ftdc1 and Ftdc2). Genetic ablation of Ftdc1 or Ftdc2 causes midgestation defects and female infertility. FTDC1 or FTDC2 depletion induces the progressive loss of DNA methylation including imprinted regions in early embryos. This loss correlates with a marked reduction in DNMT1 protein due to increased degradation, likely via the ubiquitin-proteasome pathway. Mechanistically, we find that FTDC1, FTDC2 and DNMT1 form a complex by direct interactions, thereby stabilizing each other. Surprisingly, knockout of Ftdc1 or Ftdc2 displayed stronger DNA demethylation phenotypes and earlier embryonic lethality than the Dnmt1-null mutant, implying their unique functions. These data suggest that FTDC1/2 are crucial players specifically involved in maintaining genomic methylation during embryogenesis, offering new insights into the epigenetic control of mammalian development.

DNA (Cytosine-5-)-Methyltransferase 1↗
PubMed1981

Role of the polyamines in germ cell differentiation and in early embryonic development.

The physiological function of the polyamines in germ cell differentiation and in early embryonic development was studied with the aid of the highly specific polyamine synthesis inhibitors DL-alpha-methylornithine (MO) and DL-alpha-difluoromethylornithine (DFMO). In the invertebrate Ophryotrocha labronica DFMO-induced polyamine deficiency severely affected nucleolar formation and activity in germ cell differentiation as revealed by RNA-labelling experiments and by ultrastructural analysis. Both in an invertebrate (Ophryotrocha labronica) and in a vertebrate (chick), inhibitor-induced polyamine deficiency caused a block of embryonic development at gastrulation. The major ultrastructural effect observed in the arrested embryos was an interference with nucleolar formation. Our data suggest that polyamine synthesis is essential for the ribosomal gene expression that is associated with oogenesis and embryogenesis.

Animals↗
PubMed2002

Respiration and energetics of embryonic development in a large altricial bird, the Australian pelican (Pelecanus conspicillatus).

We examined whether the previously reported low cost of embryonic development in pelicans could be attributed to a more efficient conversion of egg energy to hatchling tissues as a result of high initial egg water content, low embryonic metabolic rate and growth later in incubation than in more precocious species. We therefore determined egg and hatchling composition and the development of embryonic respiration in the Australian pelican Pelecanus conspicillatus, which lays one of the largest eggs (140-210 g) with an altricial developmental mode. The small yolk fraction (21%) is typical of all pelecaniforms; however, we found that intraspecific variability in fresh egg mass was related to water content (principally in the albumen), but independent of yolk mass (mean 13 g dry mass). P. conspicillatus eggs have, on average, 635 kJ of energy, irrespective of egg mass across the whole range of egg mass. The embryonic developmental pattern of O(2) consumption and CO(2) production showed clear plateaus lasting 2-3 days immediately prior to internal pipping, resembling the typical precocial pattern. However, the rate of pre-internal pipping O(2) consumption was low in comparison with that of precocial species of similar egg mass. There is no evidence to support the hypothesis that the observed plateau in rates of O(2) uptake is due to a diffusion limitation of the eggshell gas conductance in this species. Embryonic metabolic rate nearly doubled during the pipping period, but the mass-independent metabolic rate of the hatchling was low in comparison with that of the resting adult. The total O(2) consumed (11 063 ml) is equivalent to 217.3 kJ (or 34% of egg energy) based on indirect calorimetry and the observed respiratory exchange ratio of 0.71. Thus, the cost of development (direct calorimetry) was 0.29 kJ J(-1) in the egg (mean egg mass 168 g), which is one of lowest reported values. As a result, the production efficiency of pelican embryonic development was 61.6%, higher than the average for birds in general (56.9%) and, in particular, of seabirds that have prolonged incubation periods on the basis of egg mass. High efficiency in embryonic development in this species was attained as a result of rapid embryonic growth later in incubation, low hatchling energy density (23.6 kJ g(-1) dry matter) and dry matter content, low embryonic metabolic rate throughout incubation and a shorter than expected incubation period of 33 days (predicted 36 days).

Animals↗
PubMed2002

Changes in sex steroid levels in yolks of the leghorn chicken, Gallus domesticus, during embryonic development.

Yolk steroid hormones have been documented to have growth and behavior effects on hatchlings in several avian species. The purpose of these investigations was to determine initial levels of androstenedione (A), dihydrotestosterone (DHT), estradiol (E(2)), and testosterone (T), and document any changes in those hormones during the course of embryonic development in the Leghorn chicken, Gallus domesticus. Eggs were collected, labeled for hen of origin and egg sequence, incubated at 37.8 degrees C, and sacrificed at predetermined times during development. The embryos were staged, the yolk material collected, homogenized and hormones extracted. A, DHT, E(2), and T were separated via column chromatography and hormone levels determined using radioimmunoassays (RIAs). Results indicate a significant decrease in A and T during embryonic development, similar to that reported by our laboratory for the alligator, with A levels being significantly greater initially than levels of all other hormones. Changes in DHT mirrored changes in T levels. Chicken E(2) yolk content dynamics differ from those we have measured in both the turtle and the alligator. After an initial decline, E(2) in the yolks of chicken eggs undergoes a significant increase at the end of development, between embryonic stages 40 and 45 (days 14 and 20 of development). As the increase is much larger than could be accounted for by hormones present in the yolk material, this may represent early embryonic production of steroid hormones by the developing gonads.

Animals↗
PubMed2002

Bovine somatotropin increases embryonic development in superovulated cows and improves post-transfer pregnancy rates when given to lactating recipient cows.

Previous studies indicated that the use of bovine somatotropin (bST) in concurrence with a timed artificial insemination (TAI) protocol increased pregnancy rates. However, the mechanisms for such a bST effect on fertility were not clear. Objectives of this study were to determine the effects of bST on fertilization and early embryonic development after cows received a superovulation treatment, test whether embryos recovered from bST-treated cows were more likely to survive after transfer to recipients, and evaluate whether treatment of recipient cows with bST affects pregnancy rates. Lactating (n = 8) and nonlactating (n = 4) Holstein donor cows were superovulated, inseminated at detected estrus and assigned to a nontreated control group or to a treatment group receiving a single injection of bST (500 mg, sc) at insemination. Embryos were nonsurgically flushed 7 days after AI and frozen in ethylene glycol for direct transfer. Embryos derived from bST-treated (bST-embryos) or control (control-embryos) donors were transferred to lactating Holstein recipient cows that received either bST treatment 1 day after estrus (500 mg, sc; bST-recipients) or were untreated controls (control-recipients). Thus, there were four treatment groups: control-embryos/control-recipients (n = 43), bST-embryos/control-recipients (n = 41), control-embryos/bST-recipients (n = 37), and bST-embryos/bST-recipients (n = 60). Pregnancy was determined by palpation per rectum 33-43 days after embryo transfer. Unfertilized ova per flush was less for bST than for control (1.0 +/- 0.9 < 3.7 +/- 0.9; P < 0.04). Percentage of transferable embryos was greater for bST than for control (77.2% > 56.4%; P < 0.01). Number of blastocysts per flush was greater for bST than for control (2.4 +/- 0.7 > 0.4 +/- 0.7; P < 0.04). Pregnancy rates following embryo transfer were 25.6% for control-recipient/control-embryo, 43.2% for bST-recipient/control-embryo, 56.1% for control-recipient/bST-embryo, and 43.3% for bST-recipient/bST-embryo. Transfer of bST-embryos increased pregnancy rates compared with transfer of control-embryos (P < 0.04). An interaction between embryo and recipient treatments (P < 0.05) indicated that treatment of recipient cows with bST increased pregnancy rates as compared to control-recipients that received a control-embryo. However, there was no additive effect when bST-recipients received a bST-embryo. Administration of bST at AI decreased the number of unfertilized ova, increased the percentage of transferable embryos, and stimulated embryonic development to the blastocyst stage. Moreover, bST affected both early embryonic development and recipient components to increase pregnancy rates following embryo transfer.

Animals↗
PubMed1996

Competence of oocytes from the B6.YDOM sex-reversed female mouse for maturation, fertilization, and embryonic development in vitro.

When the Y chromosome of a Mus musculus domesticus mouse strain is placed onto the C57BL/6J (B6) inbred genetic background, the XY (B6.YDOM) progeny develop ovaries or ovotestes, but not normal testes, during fetal life. At puberty, while some of the hermaphroditic males become fertile, none of the XY sex-reversed females produce litters. We have previously demonstrated that the eggs ovulated from the B6.YDOM ovary undergo fertilization efficiently, but cannot develop beyond the 2-cell stage either in vivo or in vitro. In the present study, we collected oocytes directly from the XY ovary, and examined their maturation, fertilization, and embryonic development in vitro. The results show that the juvenile XY ovary yielded far more fertilizable oocytes by direct collection and in vitro maturation than through in vivo ovulation, but the majority of fertilized eggs failed to reach the blastocyst stage. Hence, developmental incompetence of oocytes in the XY ovary appears to be programmed during oocyte differentiation or growth. Nonetheless, in vitro matured oocytes showed a higher potential of embryonic development than the ovulated eggs, suggesting that fertility of the XY female may be impaired by multiple factors. We hypothesized that poor responsiveness of the XY ovary to gonadotropins, as we have previously demonstrated in testosterone production, may impair follicular development or proper recruitment of oocytes for ovulation. In the present study, we compared 125I-hCG binding in XX and XY ovaries, but did not find a significant difference. Hence, LH activity appears to be impaired after receptor binding in the XY ovary. On the other hand, the pattern of 125I-hCG binding indicated that the majority of antral follicles in the XY ovary failed to undergo normal preovulatory phases, which may explain the lower developmental capacity of eggs after ovulation.

Animals↗
PubMed1992

Platelet activating factor in culture media as an indicator of human embryonic development after in-vitro fertilization.

Although human chorionic gonadotrophin can detect trophoblast after implantation of the conceptus, there is a need to detect the conceptus before implantation. We have investigated whether human embryo-derived platelet activating factor is formed during embryonic development after in-vitro fertilization. A total of 99 ova from 12 patients were cultured and the 54 media were analysed. Platelet activating factor was also measured by radioimmunoassay after extraction. Fertilization increased the amount of platelet activating factor 4-fold over non-fertilized ova to a level of 4 ng/ml. This increase was also dependent on the degree of embryonic development with a maximum level of platelet activating factor of 7 ng/ml at the 2-cell stage. The follicular inducing agent used to treat the patient also had an effect on platelet activating factor; buserelin treatment gave embryos with a higher level than did clomiphene citrate treatment. These results indicate that platelet activating factor may have a role in embryonic development before implantation and may serve as a useful marker for fertilization and the developmental stage of the embryo.

Adult↗