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PubMed2001

Feed and forage toxicants affecting embryo survival and fetal development.

Early embryonic and fetal development in mammals is sensitive to deficiencies and excesses of specific nutrients and toxicants. Operating directly and/or indirectly, these deficiencies and excesses can result in embryonic death or, in less severe circumstances, disruption of normal embryo and fetal growth. This paper explores the threats posed by feed and forage toxicants to the developing embryo and their impact on early programming of fetal development. Using significant examples, we consider the relevance of temporal sensitivities during early development in utero, and their implications for the morphology and functional competence of specific organs and tissues.

Animal Feed↗
PubMed1995

Corticosteroid-binding globulin (CBG) in fetal development.

In fetal sheep the prepartum increase in plasma cortisol concentration is associated with an increase in high affinity corticosteroid binding activity in plasma. This appears to reflect an increase in corticosteroid-binding globulin (CBG) biosynthesis from the fetal liver, and evidence is presented that hepatic CBG gene expression is increased by exposure to glucocorticoids in the fetus. Immunoreactive CBG is found in other fetal tissues, and CBG mRNA is present in fetal pituitary. CBG reduces the ability of cortisol to exert negative feedback on basal or CRH-stimulated ACTH output by fetal sheep pituitary cells in culture. We suggest that CBG interacts with cortisol in a manner that maintains a low negative feedback on the pituitary, and perhaps hypothalamus. This constitutes a component of the cascade of events that is associated with hypothalamic-pituitary-adrenal activation in the late gestation fetus, and with the onset of parturition.

Animals↗
PubMed2004

Central vagal sensory and motor connections: human embryonic and fetal development.

The embryonic and fetal development of the nuclear components and pathways of vagal sensorimotor circuits in the human has been studied using Nissl staining and carbocyanine dye tracing techniques. Eight fetal brains ranging from 8 to 28 weeks of development had DiI (1,1'-dioctadecyl-3,3,3',3' tetramethylindocarbocyanine perchlorate) inserted into either the thoracic vagus nerve at the level of the sternal angle (two specimens of 8 and 9 weeks of gestation) or into vagal rootlets at the surface of the medulla (at all other ages), while a further five were used for study of cytoarchitectural development. The first central labeling resulting from peripheral application of DiI to the thoracic vagus nerve was seen at 8 weeks. By 9 weeks, labeled bipolar cells at the ventricular surface around the sulcus limitans (sl) were seen after DiI application to the thoracic vagus nerve. Subnuclear organization as revealed by both Nissl staining and carbocyanine dye tracing was found to be advanced at a relatively early fetal age, with afferent segregation in the medial Sol apparent at 13 weeks and subnuclear organization of efferent magnocellular divisions of dorsal motor nucleus of vagus nerve noticeable at the same stage. The results of the present study also confirm that vagal afferents are distributed to the dorsomedial subnuclei of the human nucleus of the solitary tract, with particular concentrations of afferent axons in the gelatinosus subnucleus. These vagal afferents appeared to have a restricted zone of termination from quite early in development (13 weeks) suggesting that there is no initial exuberance in the termination field of vagal afferents in the developing human nucleus of the solitary tract. On the other hand, the first suggestion of afferents invading 10N from the medial Sol was not seen until 20 weeks and was not well developed until 24 weeks, suggesting that direct monosynaptic connections between the sensory and effector components of the vagal sensorimotor complex do not develop until this age.

Carbocyanines↗
PubMed2001

Superovulation of female mice delays embryonic and fetal development.

Mouse and human embryos, cultured in vitro, undergo a delay in development compared with those grown in vivo. This delay can be caused by suboptimal culture conditions, but possible influences of ovarian stimulation cannot be excluded. The objective of this study was to test the hypothesis that both in vitro and in vivo, preimplantation embryonic development and postimplantation fetal development are impaired in superovulated female mice when compared with naturally cycling controls. A delay in in-vitro blastocyst hatching and in-vivo blastocyst formation (P < 0.03 and P < 0.0001 respectively) and a 40% fetal growth retardation (P < 0.0001) were observed after superovulation in comparison with naturally cycling controls. After transfer to non-stimulated foster mothers, blastocysts from stimulated females had a lower implantation rate (P < 0.005), and developed into fewer living fetuses (P < 0.02), more resorption sites (P < 0.02) and had more pronounced growth retardation (P < 0.0001) when compared with blastocysts from naturally cycling controls. In conclusion, superovulation in the mouse causes a delayed embryonic development in vitro and in vivo, an increased abnormal blastocyst formation, a pronounced fetal growth retardation, and an increased number of resorption sites. If this observation in mice can be extrapolated to humans, it may offer an explanation for the delay in embryonic development and the low birth weight observed after IVF.

Animals↗
PubMed2002

Fetal development of mouse oocytes and zygotes cryopreserved in a nonconventional freezing medium.

This study (1) analyzed fetal development of mouse embryos after oocyte cryopreservation in CJ2, a choline-based medium, (2) examined the effect of culture duration in vitro on subsequent fetal development, and (3) compared survival and fetal development of zygotes frozen in embryo transfer freeze medium (ETFM; sodium-based medium) or CJ2. Unfertilized oocytes and zygotes were cryopreserved using a slow-cooling protocol. After thawing, oocytes were inseminated after drilling a hole in their zona, cultured in vitro either to the two-cell or blastocyst stage, and transferred to the oviducts or uterine horns of recipient mice. In parallel experiments, frozen-thawed zygotes were similarly cultured and transferred. Implantation rates for transferred embryos were high (range 66-88%), regardless of whether they had been frozen as oocytes or zygotes and whether they had been transferred to the oviduct or uterus. However, fetal development was significantly higher when two-cell embryos were transferred. With blastocyst transfer, control embryos implanted and produced a greater proportion of fetuses than did oocytes frozen in CJ2, whereas transfer at the two-cell stage resulted in similar proportions of implantation sites and fetuses. Blastocyst transfer of zygotes cryopreserved in ETFM or CJ2 produced similar fetal development rates (23.6% vs 20.0%), but when frozen-thawed zygotes were transferred at the two-cell stage the fetal development rates were higher in the ETFM group (53.3%) than in the CJ2 group (32.0%). A high proportion (46.7%) of oocytes frozen in CJ2 in a nonprogrammable freezer and plunged at -20 degrees C developed into live offspring. This study shows that in the mouse (1) oocytes frozen in CJ2 can develop into viable fetuses, (2) prolonging culture in vitro has a detrimental effect on embryo transfer outcome, and (3) CJ2 offers no advantage for zygote cryopreservation.

Animals↗
PubMed1997

Effects of finasteride, a type 2 5-alpha reductase inhibitor, on fetal development in the rhesus monkey (Macaca mulatta).

In genetic male fetuses, dihydrotestosterone (DHT) plays an important role in normal prostatic and external genital differentiation. The enzyme steroid 5-alpha reductase (5 alpha R) catalyzes the conversion of testosterone (T) to DHT. The importance of 5 alpha R in sexual differentiation is evident from the study of human genetic males who congenitally lack this enzyme and consequently develop ambiguous genitalia. These individuals are specifically deficient in the type 2 isozyme, whereas the normal type 1 isozyme activity has been found. The purpose of this study was to determine 1) the suitability of the rhesus monkey for testing the safety of 5 alpha R inhibitors when administered during pregnancy and 2) the potential risk of administering a known type 2 5 alpha R inhibitor, finasteride, during the critical period of internal and external genital differentiation in rhesus monkeys. In vitro studies were also performed on selected rhesus monkey tissues to determine the distribution of the 5 alpha R isozymes. Gravid monkeys were treated once daily from gestational days (GD) 20 to 100. Sonographic monitoring was performed during the course of gestation to monitor viability, growth, and organ system development. Detailed fetal evaluations for developmental abnormalities were performed at term (GD 152 +/- 2). A group of 13 pregnant monkeys ("positive control") were given a high oral dose (2 mg/kg/day) of finasteride to demonstrate that inhibiting type 2 5 alpha R results in specific external genital abnormalities in male fetuses. Thirty-two pregnant monkeys were administered an intravenous (i.v.) formulation of finasteride at doses of 8, 80, or 800 ng/day. The highest i.v. dose selected was at least 60-750 times the semen levels of finasteride in man given orally 5 or 1 mg/day, respectively. Seventeen vehicle-control pregnant monkeys were also included. Administration of a high oral dose (2 mg/kg/day) of finasteride resulted in external genital abnormalities characterized by hypospadias, preputial adhesions to the glans, a small underdeveloped scrotum, a small penis, and a prominent midline raphe in male fetuses; however, no developmental abnormalities were seen in female fetuses. Similarly, no abnormalities were observed in either male or female fetuses of mothers given iv doses (8, 80, or 800 ng/day) of finasteride during pregnancy. The in utero sonographic findings in fetuses correlated with the gross findings at term. These studies have shown that external genital abnormalities can be produced in male monkey fetuses when exposed to a high oral dose (2 mg/kg/day) of finasteride, whereas no abnormalities were observed in fetuses exposed to the i.v. formulation of finasteride. Detailed in vitro studies demonstrated that the rhesus monkey also has two 5 alpha R isozymes (types 1 and 2) with a tissue distribution similar to that seen in man and, furthermore, that finasteride is a potent, mechanism-based inhibitor with selectivity for both human and rhesus type 2 5 alpha R. These studies have demonstrated that the monkey is a suitable model for assessing the safety of 5 alpha R inhibitors administered during pregnancy.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Maternal choline availability alters the localization of p15Ink4B and p27Kip1 cyclin-dependent kinase inhibitors in the developing fetal rat brain hippocampus.

Previously we have shown that changes in maternal dietary choline are associated with permanent behavioral changes in offspring. Importantly, in adult male rats, feeding a choline-deficient diet increases the localization of cyclin-dependent kinase inhibitors (CDKIs) in the liver, whereas young adult CDKI knockout mice (p15Ink4B or p27Kip1) exhibit behavioral abnormalities. Thus, maternal dietary choline-CDKI interactions could underlie the changes we observe in fetal hippocampal development and cognitive function in offspring. Here, timed-pregnant rats on embryonic day E12 were fed the AIN-76 diet with varying levels of dietary choline for 6 days, and, on E18, fetal brain sections were collected, and the localization of CDKI proteins was studied using immunohistochemistry and an unbiased image analysis method. In choline-supplemented animals compared to controls, the number of cells with nuclear immunoreactivity for p15Ink4b CDKI protein was decreased 2- to 3-fold in neuroepithelial ventricular zones and adjacent subventricular zones corresponding to the fimbria, primordial dentate gyrus and Ammon's horn regions in the fetal hippocampus. In contrast, maternal dietary choline deficiency significantly decreased nuclear p15Ink4b immunoreactivity in the neuroepithelial layer of the dentate gyrus. Unlike p15Ink4b, the CDKI protein p27Kip1 was observed almost exclusively in the cytoplasm, though the protein was distributed throughout the proliferating and postmitotic zones in the E18 fetal hippocampus. Maternal dietary choline supplementation decreased the cytoplasmic staining intensity for p27Kip1 throughout the fetal hippocampus compared to control animals. Choline deficiency increased the staining intensity of p27Kip1 throughout the hippocampus in association with increased expression of MAP-1 and vimentin proteins. These results link maternal dietary choline availability to CDKI protein immunoreactivity and commitment to differentiation during fetal hippocampal development.

Animal Nutritional Physiological Phenomena↗
PubMed1990

[Fetal development of the omasum of cattle (Bos taurus)].

Structures characteristic of the omasum are already present by the third month of development. The fetal omasal laminae exhibit their typical arrangement (1434243414). Muscle fibers from the lamina circularis also extend into the first through third order laminae at this stage. Conical projections and small secondary papillae begin to appear on the laminae as the fetus ages. The lamina muscularis mucosae can be found in all of the laminae by the fourth to fifth month of development. The cuboidal to columnar epithelium of the stratum basale remains largely unaltered throughout the course of fetal development, whereas the stratum superficiale is subjected to a continuous series of changes. Superficial cell layers increase and the glycogen content of the epithelial cells fluctuates significantly.

Animals↗
PubMed1986

[Evaluation of fetal development and well-being with the ultrasonic Doppler fetal actocardiograph].

Fetal development and well-being were investigated during pregnancy with respect to the relation between fetal movement (FM) and fetal heart rate (FHR) in 192 normal and 43 high-risk fetuses in the antepartum period utilizing ultrasonic Doppler fetal actocardiograph that enabled the simultaneous and continuous recording of FM and FHR by single ultrasonic probe. The analysis of simultaneously obtained records of FHR and the movements of fetal trunk and legs revealed that gross fetal trunk movement was mainly related with FHR acceleration. The number of FM signal bursts, which was accompanied by fetal trunk rotating movements, showed a peak at 30-31 weeks of gestation and decreased in the other stage of pregnancy. The synchronization rate of FM signal bursts to transient FHR rises increased with gestational age, and the amplitude and inclination of the rise accompanied by bursts increased linear from the 24th to the 38th week of gestation. Fetuses of high-risk pregnancy produced on antepartum actocardiogram with low FM and FHR values. The changes were particularly remarkable in the cases of intrauterine growth retardation and/or gestosis.

Embryonic and Fetal Development↗
PubMed1984

[Hemodilution and anemia in pregnancy and fetal development].

The relation between hemodilution or anemia of pregnancy and fetal development was studied in 350 pregnant women who were delivered of full term singleton infants and were without any complications except iron deficiency anemia. The mean birth weight of the infants whose mother's hematocrit levels were 28.0-31.9% in 28-32 weeks' gestation was significantly higher than those of infants whose mother's hematocrits were 32.0-35.9% and 36.0-39.9%. There was also observed the same relation between birth weights and mother's hematocrits in 36-37 weeks' gestation. The incidence of small for dates infants was not significantly different between pregnant with different hematocrits. The iron deficiency anemia of pregnancy had no adverse effects on fetal development. It was suggested that hemodilution of pregnancy had an important physiological role in improving placental microcirculation to accelerate fetal development.

Anemia↗
PubMed1976

Gene activation of molecules with carcinoembryonic antigen determinants in fetal development and in adenocarcinoma of the colon.

"Fingerprints" of 0.9% NaCl solution extracts obtained from fetal guts and individual adenocarcinoma of the colon show a randomized pattern of expression of carcinoembryonic antigen (CEA) determinants by CEA radioimmunoassay and isoelectric focusing. All CEA-containing antigens found in a pool of 20 primary adenomas were found at some stage in fetal development. No single CEA-reacting peak was typical of any one period of fetal development. When fetal gut profiles were grouped according to trimester in utero, however, an expanded gene pool was found in the second trimester which correlates well with maximum gastrointestinal growth and differentiation. Isoelectric focusing-CEA radioimmunoassay profiles of individual primary adenomas were similar to but never identical with individual fetal gut profiles. "Fingerprints" of metastatic adenomas of entodermal origin showed quantitative and qualitative increases in molecules with CEA determinants unlike these latter categories. Such data suggest that both integrator and controller gene activities may be lost in metastatic disease. Rather than "phase-specific gene sets" on different chromosomes being activated by various oncogenic modalities, it is more probable that individual chromosomes are involved in oncogenesis. While more data are needed to confirm this idea, it is safe to say that the expression of molecules with CEA determinants need not be caused by either derepressive or reexpressive gene activation. These data point to the individuality of gene expression of molecules with CEA determinants both in fetal development and in early neoplasia. Since CEA-reacting molecules were not found in tumors of ectodermal or mesodermal origin by these methods, such products should be termed carcino-developmental antigens of entodermal or colonic origin.

Adenocarcinoma↗
PubMed2005

Maternal cholesterol in fetal development: transport of cholesterol from the maternal to the fetal circulation.

Cholesterol is required for fetal development. Data obtained from recent studies in humans, rodents, and cell cultures showed that circulating maternal cholesterol can affect fetal metabolism and sterol accretion. Recent studies in our laboratory showed that the efflux of cholesterol from the basolateral side of the placental cells and the secretion of cholesterol from endodermal yolk sac cells to the fetal circulation can be regulated. The ability to manipulate the mass of maternal cholesterol that crosses to the fetus could result in a dramatic improvement in the development of fetuses that lack the ability to synthesize cholesterol, such as those with Smith-Lemli-Opitz syndrome. On the other hand, it could also accelerate the development of various age-related diseases, such as atherosclerosis.

Biological Transport, Active↗
PubMed1995

Expression of amphiregulin is regulated in cultured human keratinocytes and in developing fetal skin.

Previous studies have indicated that amphiregulin is a major autocrine factor for human keratinocytes. To evaluate the possibilities that amphiregulin could function in fetal skin morphogenesis and contribute to the growth regulation of epidermis, immunostaining with a specific anti-amphiregulin monoclonal antibody was observed at different stages of fetal skin development, and the results were compared with neonatal and adult skin specimens and cultured neonatal keratinocytes. Immunoreactive amphiregulin was readily detected in the periderm and basal epidermal layers of embryonic epidermis but became gradually less detectable in the periderm concurrent with an increase in staining of the spinous layer as it developed during the fetal period. Basal and spinous keratinocyte expression of amphiregulin was predominantly cytoplasmic, but with punctate nuclear foci, and this pattern persisted into the neonatal period. At all developmental stages, epithelial and mesenchymal cells of the follicle were reactive, often in a nuclear pattern. Dermal mesenchymal cells were increasingly reactive in late fetal skin, but the staining decreased postnatally. In adult skin only randomly scattered nuclei of spinous keratinocytes and follicular structures such as the inner root sheath were stained. Examination by scanning laser confocal microscopy of cultured neonatal keratinocytes showed a nonrandom distribution of amphiregulin to the peripheral cytoplasm and plasma membranes at the outer perimeter of cell colonies, with much less reactivity of apposed keratinocyte membranes at interior sites. Nuclei were heterogeneously stained. Amphiregulin reactivity declined at higher cell densities. These data indicate that expression of amphiregulin is regulated in vitro and developmentally during cutaneous morphogenesis.

Adult↗
PubMed1982

Experimental studies on the influence of male alcoholism on fetal development.

To study the effect of paternal chronic ethanol consumption on fetal development, an experimental rat model was established and compared to the fetal alcohol syndrome. Male and female Wistar rats were divided into 30% ethanol (E) and control groups. Before mating and during pregnancy the ethanol group and control group received E and water, respectively. Pregnancies were terminated on gestational day 21. The body weight, liver weight, blood glucose, serum insulin and cerebral CNPase activity were decreased in alcoholic males. The adverse effect of maternal chronic ethanol on fetal development was shown clearly and was not related to paternal ethanol. The adverse effect of paternal alcoholism on the fetus was shown in decreased litter size, or decreased body weight, cerebral weight and cerebral DNA, RNA and leucine incorporation into protein without a decrease in the litter size. The former finding was observed in the fetuses of aged male and female rats and latter in the fetuses of young female rats. In conclusion, both observations in our study indicate the adverse effect of paternal alcoholism on the fetal development.

Alcoholism↗
PubMed1997

Maternal diabetes induces upregulation of hepatic insulin-like growth factor binding protein-1 MRNA expression, growth retardation and developmental delay at the same stage of rat fetal development.

Since maternal diabetes is associated with fetal growth abnormalities in humans and rats, effects of maternal diabetes on fetal expression of genes regulating growth are of interest. Increased expression of Insulin-Like Growth Factor Binding Protein-I (IGFBP-1) is associated with several examples of growth retardation and is upregulated in response to diabetes. As we have shown previously, IGFBP-1 expression is upregulated in gestational day (GD) 14 rat fetuses in response to maternal diabetes. Here we analyze the effect of streptozotocin-induced maternal diabetes on IGFBP-1 mRNA expression during GD12-16 of rat fetal development, using in situ hybridization. IGFBP-1 mRNA was more abundant in GD12-14 fetal livers from diabetic dams than in livers of age-matched controls. This upregulation is not due to the approximately 1-day fetal developmental delay associated with maternal diabetes, as there is no gross difference in the level of IGFBP-1 mRNA in GD13 vs GD12 or GD14 vs GD13 control fetal livers. At GD15-16, however, we detected little difference in IGFBP-1 expression between experimental and control fetuses. This transient period of maternal diabetes-stimulated IGFBP-1 mRNA expression (GD12-14) is coincident with the sensitive period for maternal diabetes-induced defects in fetal growth and development, suggesting that IGFBP-1 is involved in the regulation of fetal growth and development in response to the maternal condition.

Animals↗
PubMed2005

Contractile properties of the developing fetal sheep bladder.

AIM: To characterise the developmental changes to the normal bladder by examining the in vitro contractile properties of the fetal sheep detrusor smooth muscle bladder at different gestational ages. METHODS: Three groups of normally developing fetal sheep bladders were investigated: (1) 65-70 days gestation (2nd trimester); (2) 105-110 days (3rd trimester); (3) 135-140 days (term). Isometric contractions in isolated detrusor strips were measured during either electrical field stimulation (EFS) or exposure to agonists: carbachol, alpha-beta methylene-ATP (ABMA) and KCl. RESULTS: There was a significant increase of absolute force elicited by EFS with fetal age. Contractures elicited by carbachol, ABMA and KCl increased between Groups 1 and 2, but not thereafter. The proportional increase of contractions elicited by carbachol and ABMA was also greater between Groups 1 and 2, than for EFS and KCl. CONCLUSIONS: Fetal development between 65 and 140 days in the sheep is associated with increased contractile activation. The data are consistent with an increase of muscle development in the earlier stages (65-110 days). In the later stage (110-140 days) muscle development is complete but functional innervation of the tissue continues.

Adenosine Triphosphate↗