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PubMed1989

Effects of eflornithine hydrochloride (DFMO) on fetal development in rats and rabbits.

Eflornithine hydrochloride (DFMO) is a highly selective, enzyme-activated, irreversible inhibitor of the enzyme L-ornithine decarboxylase (ODC). Because of its role in the biosynthetic pathway of polyamines, ODC is essential for the growth and development of newly implanted embryonic tissue. In order to assess its effect on embryonic growth and fetal development, at various stages of gestation, DFMO was administered in the drinking water to pregnant rats and rabbits at several concentrations (from 0.03% to 3.0%) and times (from days 7, 10, or 11 through days 18 or 19). Rats were killed on day 21 and rabbits on day 29 of pregnancy (day 1 = day of insemination), and the implantations and fetuses were examined. At a concentration of 1.0% (approximately 1,270 mg/kg/day) in rats and 3.0% (approximately 915 mg/kg/day) in rabbits, maternal food and water consumption and body weight gain were significantly reduced during the treatment period, and all implantations were aborted or resorbed. At lower doses (approximately 200-600 mg/kg/day) fetuses survived to term, though in reduced numbers, and a marked reduction in average fetal weight was seen. At levels of 60 mg/kg/day or lower, there were no deleterious effects to the dams or their offspring. Few malformations were detected at any dose level by gross teratologic examination; nor were any considered to have been drug induced because of their sporadic incidence. The embryotoxicity and severe growth retardation demonstrated by these studies verify that adequate polyamine levels are essential for normal embryonic and fetal development.

Abnormalities, Drug-Induced↗
PubMed2003

IGF-I, 17beta-estradiol and progesterone in SHR and in rats treated with L-NAME: fetal-placental development.

METHODS: The relationship between progesterone (P4), 17beta-estradiol, insulin-like growth factor (IGF-I) and embryonic and fetal development, were examined. Female Sprague Dawley rats were divided into two groups: control untreated (n=60) and treated (n=63) with L-NAME (N(omega)-nitro-L-arginine methyl ester), 15 mg/day in drinking water from the first day after mating to day 18 of gestation. A further group was formed (n=63) of spontaneously hypertensive rats (SHR). Mean systolic blood pressure was recorded daily. On days 6, 11 and 18 of pregnancy, the number of sites of implantation, litter and placenta weight was examined. In addition, serum levels of P4, 17beta-estradiol and IGF-I were determined. RESULTS: Systolic blood pressure (SBP) (mmHg) increased significantly in L-NAME and SHR rats over the course of the experiment. On day 6 of pregnancy, in the L-NAME group the number of implantation sites, levels of IGF-I and 17beta-estradiol were significantly lower than in the control group. In SHR, only the concentration of IGF-I was low (p<0.05). In contrast, on day 11 of pregnancy no variation was found in the parameters under study. On day 18 of gestation, a significant decrease in litter and placenta weight, concentration of P4 and IGF-I was observed in the experimental groups. CONCLUSION: The data further suggest that nitric oxide might regulate IGF-I production, indicating that growth factors may play an important role in fetal-placental development.

Animals↗
PubMed1984

Reproduction and teratology studies on hexamethylmelamine in the rat and rabbit.

The antineoplastic drug hexamethylmelamine (HMM) was evaluated for effects on reproduction and postnatal development in the rat and on embryonal and fetal development in the rat and rabbit. Daily po treatment of male rats for 62 days with doses of 0, 10, 20, or 40 mg/kg/day resulted in testicular atrophy, reduced fertility, and a possible dominant lethal mutagenic effect at the higher two dose levels. Alterations in morphology and function of the beta cells of the pancreatic islets were observed after treatment of males for more than 28 days with 20 or 40 mg/kg/day. The same dose levels administered to female rats for 14 days prior to breeding and through Day 13 or 20 of gestation had no adverse effects on fertility, but the highest dose was embryocidal and postnatal survival was decreased at both the 20- and 40-mg/kg/day dose levels. Similar effects on postnatal survival were observed when the drug was administered by gavage to rats during the last week of gestation and throughout the lactation period. Treatment of pregnant rats throughout organogenesis (Days 6 to 15) or for 4-day intervals during organogenesis (Days 6 to 9, 9 to 12, or 12 to 15) with po doses ranging from 20 to 80 mg/kg/day resulted in decreased body weight gain and food consumption, an increased resorption rate in dams receiving 80 mg/kg/day on Days 6 to 9, and decreased fetal weights at all dose levels and most treatment intervals. The incidence of minor skeletal defects was increased among litters of HMM-treated groups. Major fetal malformations were limited in number but were considered treatment related. Treatment of pregnant rabbits po on Days 6 to 18 of gestation with doses of 0, 20, 40, or 60 mg/kg/day did not result in an embryocidal or teratogenic effect. Treatment with 60 mg/kg/day did, however, result in decreased kit weights, indicating a mild embryo-fetotoxic effect.

Abnormalities, Drug-Induced↗
PubMed1994

[Morphology of the neuroendocrine-immunologic network of connective tissue in rodent fetal development].

Multi-range neuro-endocrine-immunological function in regulation of body homeostasis gives reasons for establishment of peripheral morphological bonds. As a result from our study, the unit of trophic protection of pelvic connective tissue was identified in embryonal and fetal development of rodents. This unit connects blood vessels and their autonomic innervation with chromaffin cells, mast cells, and simple neurons. Nerve fibres of para-organ pelvic ganglions determine to complete. Author suggestion on integration of another connective tissue cells and erythroid cells with systemic network requires verification.

Animals↗
PubMed1990

Cardiac troponin T in developing, regenerating and denervated rat skeletal muscle.

Fetal rat skeletal muscles express a troponin T (TnT) isoform similar to the TnT isoform expressed in the embryonic heart with respect to electrophoretic mobility and immunoreactivity with cardiac TnT-specific monoclonal antibodies. Immunoblotting analyses reveal that both the embryonic and the adult isoforms of cardiac TnT are transiently expressed during the neonatal stages. In addition, other TnT species, different from both cardiac TnTs and from the TnT isoforms expressed in adult muscles, are present in skeletal muscles during the first two postnatal weeks. By immunocytochemistry, cardiac TnT is detectable at the somitic stage and throughout embryonic and fetal development, and disappears during the first weeks after birth, persisting exclusively in the bag fibers of the muscle spindles. Cardiac TnT is re-expressed in regenerating muscle fibers following a cold injury and in mature muscle fibers after denervation. Developmental regulation of this TnT variant is not coordinated with that of the embryonic myosin heavy chain with respect to timing of disappearance and cellular distribution. No obligatory correlation between the two proteins is likewise found in regenerating and denervated muscles.

Animals↗
PubMed2002

The effects of epidermal growth factor on gene expression in human fibroblasts.

A better understanding of the molecular effects of epidermal growth factor (EGF) on target cell can help to reveal important aspects of cellular proliferation, transformation, and apoptosis, as well as embryonic and fetal development. In this study, we examined the differences in gene expression of cultured fibroblasts with EGF stimulation for 48 h by using high-density complementary deoxyribonucleic acid (cDNA) arrays. We found that EGF could cause widespread alteration in gene expression. Eight hundred and fifty-five genes, more than 20% of those assayed, showed changed expression, which are involved in various cellular processes, such as energetic metabolism, biosynthesis, the progress of cell cycle, and the signaling pathways of receptor tyrosine kinase (RTKs) and G protein-coupled receptors (GPCRs). The most striking finding is that long-term EGF treatment on cultured fibroblasts resulted in down-regulation of the genes encoding membrane receptors and ion channels and desensitized RTKs and GPCRs to their physiological and nonphysiological stimuli, which seems to be a slow-acting, but permanent, effect of EGF on RTK and GPCR signaling pathways and to play important roles in embryonic and fetal development.

Cell Line↗
PubMed2003

Effects of fluoride on Xenopus embryo development.

Fluoride was first associated with fetal malformation shortly after water fluoridation was initiated in the 1940s. Since many chemicals can interact directly with the embryo to cause malformation, the effects of fluoride on embryonic and fetal development were investigated. The effects of sodium fluoride on the development of frog embryos were studied under conditions described by the Frog Embryo Teratogenesis Assay-Xenopus (FETAX), a screening assay for teratogens. The most prominent malformations caused by sodium fluoride are reduction in the head-tail lengths and dysfunction of the neuromuscular system of the tadpoles. The values for LC50, EC50, and minimal concentration to inhibit growth (MCIG) of sodium fluoride met the limits established for a teratogen in frog embryos, showing that sodium fluoride is a direct acting teratogen on developing embryos. Since FETAX has a high degree of success in identifying mammalian teratogens, the observed teratogenic action of sodium fluoride on frog embryos would indicate a strong possibility that sodium fluoride may also act directly on developing mammalian fetuses to cause malformation.

Animals↗
PubMed1991

Reciprocal embryo transfer between SHR and WKY. II. Effect on cardiovascular development.

In order to study the in vivo effect of putative hypertensinogenic factors on early development of the cardiovascular system, embryos were reciprocally transferred between WKY and SHR to allow embryonic and fetal development of WKY in a hypertensive intrauterine environment and SHR in a non-hypertensive uterine environment. In one day-old neonates blood vessel dimensions and blood pressures were assessed. Pressures were also measured in animals which matured to the adult stage to determine whether there were any long-term effects on pressure of having developed in an in utero environment different from the one they would have naturally experienced. The data indicate that there are no consistent effects of intrauterine environment on vascular development, as indicated by the fact that normalized wall/lumen ratios were not different between normal and transferred animals, and immediate and long-term pressures were also similar in normal and transferred groups.

Animals↗
PubMed1996

Synchronized order of appearance of hyaluronic acid (or acidic galactan) --> chondroitin C-6 sulfate --> chondroitin C-4/C-6 sulfate, heparan sulfate, dermatan sulfate --> heparin during morphogenesis, differentiation and development.

The synthesis of glycosaminoglycans and acidic polysaccharides during embryonic and fetal development in mammals and molluscs is briefly reviewed. A sequential order of appearance of each of the acidic polysaccharides was observed, coinciding with the major processes of the ontogeny. In mammals, hyaluronic acid is the first glycosaminoglycan synthesized at the beginning of morphogenesis. This glycosaminoglycan is then replaced by chondroitin 6-sulfate during the migration of the mesenchymal cells. Heparan sulfate, dermatan sulfate and chondroitin 4-sulfate are synthesized only during cell differentiation. The synthesis of heparin, on the other hand, is confined to mast cells in a few tissues and is a late event in the differentiation process. The same general pattern is also observed in molluscs except that hyaluronic acid is replaced by an acidic galactan in the morphogenetic process. The activity of the degrading enzymes responsible for the disappearance of hyaluronic acid, chondroitin sulfate and the acidic galactan in each phase of embryonic development is also reviewed.

Animals↗
PubMed1991

Lack of effect of peritoneal endometriosis on fertility in the rabbit model.

STUDY OBJECTIVE: To study the isolated influence of peritoneal endometrial implants on fertility in an adhesion-free rabbit model. STUDY DESIGN: Thirty-two rabbits with endometrium implants were used; 31 rabbits with fat implants served as controls. In these rabbits parameters of early embryonic development were investigated. RESULTS: No significant differences were noted in ovulation, ovum pick-up, fertilization, tubal transport, and embryonic and fetal development. CONCLUSION: In the adhesion-free rabbit model, peritoneal implants of endometriosis do not have an effect on fertility. This supports the contention that therapies focused toward the implants are unlikely to change the pregnancy outcomes. Alternatively, it may cast doubts onto the relevance of animal models in studying this disease.

Animals↗
PubMed1991

Peptide growth factors: the parallel between fetal development and malignant transformation.

Normal embryonic development and tissue homeostasis depend upon cell-to-cell and tissue-to-tissue communication. Much of this depends upon the production and release of peptide growth regulators such as fibroblast growth factor, epidermal growth factor, etc. As the molecular basis of malignant transformation has been documented, it is apparent that a common means by which a tumor becomes autonomous of external control is by becoming independent of the need for external growth factor stimulation. This can occur through the cell producing and releasing the growth factors needed for its own growth. A similar end result can occur with growth factor receptor mutants in which the receptor gives a positive signal even when no growth factor is bound to the receptor. One potential therapeutic strategy is to interfere with this autocrine loop. Suramin is presented as an example of a drug capable of blocking such autocrine loops. This drug also reverses malignant transformation due to Platelet Derived Growth Factor and K-fgf/hst oncogenes on this basis. Another potential mechanism to accomplish the same end is through the use of monoclonal antibodies to either the growth factor or its receptor. Examples of this are available for TGF-alpha. We have discussed a range of practical issues involved in developing monoclonal antibodies as therapeutic agents.

Antibodies, Monoclonal↗
PubMed2003

Metaphase II nuclei generated by germinal vesicle transfer in mouse oocytes support embryonic development to term.

BACKGROUND: Cytoplasmic defects are thought to cause aneuploidies in oocytes and embryos and oocyte 'reconstruction' by germinal vesicle (GV) transfer may circumvent such defects. In mice 'reconstructed' oocytes undergo meiosis and fertilize normally, but early embryonic development is compromised if their ooplasm matured in vitro. This study employs sequential MII spindle and/or pronucleus (PN) transfer to assess the embryonic potential of MII nuclei that form following GV transfer. METHODS AND RESULTS: Mouse embryos generated by these procedures were transferred to the oviducts of pseudopregnant mice to monitor pregnancy outcome. Following GV transfer, the resultant metaphase II (MII) nuclei were activated either in situ or transferred and activated in ooplasts from in-vivo matured oocytes. When exchanged with the female PN of a fertilized zygote, only the PNs that developed in in-vivo matured ooplasts generated live offspring. Viable offspring also resulted when MII nuclei were transferred to in-vivo matured ooplasts and fertilized by insemination with sperm or by artificial activation and male PN transfer. Significantly, the offspring displayed normal fertility as adults. CONCLUSION: This report of live births following GV transfer in mice illustrates the importance of the maturational history of the ooplasm at PN formation for normal embryonic and fetal development.

Animals↗
PubMed1991

Regional development of Langerhans cells and formation of Birbeck granules in human embryonic and fetal skin.

The regional development of Langerhans cells (LC) and the formation of Birbeck granules (BG) were examined in human embryonic and fetal skin. Samples were obtained from multiple anatomic sites and stained with anti-CD36, anti-CD1a, and anti-HLA-DR antibody as well as Lag antibody specifically reactive to BG and some vacuoles of human LC. In the first trimester, CD36+ dendritic epidermal cells were identified before the appearance of CD1a+ cells and Lag+ cells. Some of the former co-expressed HLA-DR antigens but not CD1a antigens. In the second trimester, regional variations in LC development were observed. Epidermal LC of palms and soles reached a peak in number in the first trimester but were rarely detected after 18 weeks estimated gestation age (EGA), whereas, in other regions, their number increased with age. In the second trimester, CD1a+ cells and Lag+ cells were also identified in the epidermis, although Lag+ cells appeared later than CD1a+ cells. The Lag+ cells until 17 weeks EGA showed a variety of staining intensities and immunoelectron microscopy revealed that they contained various amounts of Lag-reactive BG. Flow cytometric analysis showed that relative amounts of Lag antigens in LC increased during the second trimester and that fetal LC of 18 weeks EGA expressed the same amounts of HLA-DR, CD1a, and Lag antigens as did adult human LC. In the dermis, in the second trimester, numerous CD36+ cells and HLA-DR+ cells were found, whereas CD1a+ cells and Lag+ cells were rarely detected. Taken together, it is suggested that HLA-DR+ dendritic cells acquire CD1a+ antigens first and then form BG after migration to the epidermis and that fetal LC are phenotypically mature in the second trimester.

Antigens, CD↗
PubMed2001

Immunolocalization of an FGF-binding protein reveals a widespread expression pattern during different stages of mouse embryo development.

Fibroblast growth factors (FGFs) play important roles during fetal and embryonic development. FGF-2 (basic FGF, bFGF) is widely expressed in the embryo and has been linked to tissue growth and remodeling. However, it is tightly bound to heparin sulfate proteoglycans of the extracellular matrix which quenches its biological activity. We showed previously that a secreted FGF-binding protein (FGF-BP) can mobilize and activate FGF-2 from the extracellular matrix. While considerable data exist on the expression and pivotal role of FGF-BP in tumor growth, less is known about FGF-BP during embryonic development. In this immunohistochemical study in mice, we show FGF-BP protein expression in a broad spectrum of tissues at various stages between day 8 and day 16 of embryonal development, and compare FGF-BP and FGF-2 immunolocalization. FGF-BP is detected in the digestive system, thymus, skin, hair follicles, dental germ, respiratory tract, various glandular tissues, kidney, liver, and certain areas of the CNS, with immunoreactivity being mainly confined to cells of primitive epithelia. The putative significance of these findings with regard to mobilization of FGF-2 or other molecules is discussed. From the locally confined, time-dependent, and apparently tightly regulated FGF-BP expression we propose that FGF-BP may play an important role in embryonic development.

Adrenal Glands↗
PubMed1990

Embryonic stem cells alone are able to support fetal development in the mouse.

The developmental potential of embryonic stem (ES) cells versus 3.5 day inner cell mass (ICM) was compared after aggregation with normal diploid embryos and with developmentally compromised tetraploid embryos. ES cells were capable of colonizing somatic tissues in diploid aggregation chimeras but less efficiently than ICMs of the same genotype. When ICM in equilibrium with tetraploid and ES in equilibrium with tetraploid chimeras were made, the newborns were almost all completely ICM- or ES-derived, as judged by GPI isozyme analysis, but tetraploid cells were found in the yolk sac endoderm and trophectoderm lineage. Investigation of ES contribution in 13.5 day ES in equilibrium with tetraploid chimeras by DNA in situ hybridization confirmed the complete tetraploid origin of the placenta (except the fetal blood and blood vessels) and the yolk sac endoderm. However, the yolk sac mesoderm, amnion and fetus contained only ES-derived cells. ES-derived newborns failed to survive after birth, although they had normal birthweight and anatomically they appeared normal. This phenomenon remains unexplained at the moment. The present results prove that ES cells are able to support complete fetal development, resulting in ES-derived newborns, and suggest a useful route for studying the development of genetically manipulated ES cells in all fetal lineages.

Animals↗
PubMed2000

Mitochondrial DNA segregation in the developing embryo.

Mitochondrial (mt)DNA is strictly maternally inherited in mammals; new mutations thus segregate along maternal lineages without the benefit of homologous recombination with mtDNA of paternal origin. Despite the high mtDNA copy number (approximately 100000 or more) in mature oocytes, and despite the relatively small number of cell divisions during oogenesis, mtDNA sequence variants segregate rapidly between generations. This paradoxical behaviour has been ascribed to the presence of a mtDNA 'bottleneck' in oogenesis or early embryogenesis. The nature and size of this bottleneck have been the subject of much controversy. This review argues that segregation of mtDNA sequence variants in the female germline occurs primarily during mitosis in the oocyte precursor population. Segregation is rapid because the precursor cells (primordial germ cells and oogonia) contain a relatively small number of mtDNA templates (the bottleneck) and because the replication of mtDNA is under relaxed control. For the most part, the process appears similar in mice segregating polymorphic sequence variants and in human pedigrees segregating pathogenic point mutations. In particular, there is no evidence for selection against high levels of pathogenic mtDNA point mutations in oogenesis, in early embryonic development, or in fetal development, thus suggesting that efficient respiratory chain function is not critical until post-natal life. These results have important practical implications for clinical genetics.

Chromosome Segregation↗