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At least 271 records · Page 15Linked to original sources
PubMed1991

Fetal development and gestational changes in Bos taurus and Bos indicus genotypes in the tropics.

Weights of the gravid uterus and fetus as well as the fetal measurements were determined at slaughter for 107 Bos taurus cows grazed on improved pastures and for 70 Bos indicus cows grazed on native pastures in northern Australia. The stage of gestation was assessed from palpation per rectum in early-to-mid gestation and at slaughter and from fetal development characteristics at slaughter. The age and breed of the cow and the sex of the fetus did not significantly affect any of the uterine components or fetal measurements. Growth curves had dominant, positive linear components but negative quadratic ones, which improved the fit, particularly for the later stages of gestation. Uterine components and fetal measurements were highly correlated (0.94 to 0.99). For Bos taurus cows, there were higher estimates at birth for weights of the gravid uterus and the fetus, but estimates for other fetal measurements were similar to those for Bos indicus cows. Major fetal growth occurred during the third trimester, with the length of the foreleg tending to change relatively slowly and the head width quite fast during the first trimester. Correction factors for cow liveweight to adjust to commonality for non-pregnancy were 5, 7, 10, 14, 20, 29, 43 and 65 kg for Bos taurus and 2, 4, 6, 10, 15, 23, 35 and 51 kg for Bos indicus at 2 to 9 months of gestation.

Journal Article↗
PubMed1982

Bendectin and fetal development. A study of Boston City Hospital.

As part of a prospective study investigating maternal characteristics and habits during pregnancy and their impact on fetal development, 1,690 mother/infant pairs were studied. Of the mothers, 375 reported using Bendectin during pregnancy. Multivariate analyses examining birth weight, length, head circumference, gestational age, and congenital malformations as dependent variables demonstrated no associations between Bendectin exposure and adverse fetal outcome.

Abnormalities, Drug-Induced↗
PubMed1984

Effect of short-term exposure to five industrial metals on the embryonic and fetal development of the mouse.

An increase is expected in the world's industrial use of several metals, Al, Co, Mo, V, and W, among others. Very little is known about their possible effects on early mammalian development. Groups of mice were injected with compounds of these metals either before implantation or at early organogenesis. None of the metal compounds showed any interference with implantation, but all of them significantly affected fetal development: Al caused an increased frequency of fetal internal hemorrhage, Mo inhibited fetal normal weight gain, W increased the frequency of resorptions, and Al, Co, Mo, and V all interfered with fetal skeletal ossification.

Animals↗
PubMed1988

5'-Nucleotidase and adenosine deaminase in developing fetal guinea pig brain and the effect of maternal hypoxia.

The activity of key enzymes of adenosine metabolism was studied in the developing fetal guinea pig brain. The activities of 5'-nucleotidase and adenosine deaminase were determined in the brains of fetal guinea pigs at 30, 35, 40, 45, 50, 55, and 60 days of gestation. The level of 5'-nucleotidase activity was extremely low at 30 and 35 days of gestation but increased rapidly during the 40 to 60 day period. The enzyme activity increased in the presence of Mg2+ with the Mg2+ - dependent activation increasing with the age of gestation. This Mg2+ - dependent activity was primarily associated with the membrane fraction. Prenatal hypoxia significantly increased the fetal brain M2+ - independent 5'-nucleotidase activity at 45 days of gestational age and beyond. Prior to this age, no effect was evident. Furthermore, following hypoxia, the Mg2+ - dependent activation of 5'-nucleotidase activity was lost. The activity of adenosine deaminase was present at 30 days of gestation and, unlike 5'-nucleotidase, it remained at the same level until 60 days. The results indicate that the term fetal guinea pig brain has the enzymatic mechanisms of adenosine metabolism and thus the potential for adenosine-mediated regulation of cerebrovasculature during hypoxia.

5'-Nucleotidase↗
PubMed1995

Expression of CD44 molecules and CD44 ligands during human thymic fetal development: expression of CD44 isoforms is developmentally regulated.

It has recently been recognized that CD44 comprises a large family of alternatively spliced forms. In the thymus, CD44 has been postulated to play an important role in immature T cell migration and maturation. In this paper, we have studied the expression of CD44 molecules and two CD44 ligands, hyaluronan (HA) and fibronectin (FN), during human thymic fetal development. We found that mAbs against all CD44 isoforms (A3D8 or A1G3) reacted with both thymic epithelial (TE) cells and thymocytes beginning at the time of initial colonization of the human thymus by hematopoietic stem cells at 8.2 weeks of fetal gestation. However, mAbs specific for splice variants of CD44 containing membrane-proximal inserts (11.24, 11.10 and 11.9) reacted only with terminally differentiated TE cells in and around Hassall's bodies beginning at 16-19 weeks of fetal gestation. Studies of differentiated versus undifferentiated TE cells in vitro confirmed the selective expression of CD44 variant isoforms on terminally differentiated TE cells. Expression of HA and FN was determined by fluorescence microscopy using either biotinylated-HA binding protein or an anti-FN mAb. We found that whereas FN was present throughout the human fetal thymus beginning at 8.2 weeks, HA was not present until 16 weeks of gestational age. These data demonstrate the differential expression of standard versus variant CD44 isoforms during thymic ontogeny and implicate CD44 interactions with ligands other than HA as important in the earlier stages of human thymus development.

Antibodies, Monoclonal↗
PubMed1977

Vitamin A and retinol-binding protein metabolism during fetal development in the rat.

Studies were conducted on the metabolism and placental transport of vitamin A and plasma retinol-binding protein (RBP) during fetal development in the rat. Vitamin A accumulated in the conceptus in three phases: an early phase (days 7-9 of gestation) characterized by a high vitamin A concentration; a second phase (days 11-14) where vitamin A and RBP accumulated in parallel; and a third phase of continued vitamin A and RBP accumulation (days 16-20) in which vitamin A was stored in the fetal liver. The early phase of vitamin A accumulation may reflect a mechanism that exists to prepare the conceptus to meet the presumably higher vitamin A requirements of the critical period (days 10-14) of organ differentiation. Fetuses and placentas from retinol-deficient dams showed low levels of RBP through days 16-18 of gestation. A retinol-repletion study suggested, moreover, that the maternal retinol-RBP complex crossed the placenta. The various studies all suggest that vitamin A is transported from dam to fetus, from and after day 11, mainly by transplacental transport of maternal retinol-RBP. Finally, evidence was obtained indicating that the fetal liver begins to synthesize RBP around the 16th day of gestation and that by the 20th day, the fetal liver has a considerable capacity for RBP synthesis.

Animals↗
PubMed1986

Human placental lactogen and unconjugated estriol concentrations in twin pregnancy: monitoring of fetal development in intrauterine growth retardation and single intrauterine fetal death.

Human placental lactogen and unconjugated estriol concentrations in maternal serum were evaluated in 100 uneventful twin pregnancies, and these values were compared with those observed in 16 twin pregnancies associated with intrauterine growth retardation or single intrauterine fetal death. In pregnancies associated with intrauterine growth retardation (n = 8), human placental lactogen levels were at the lower limit of normal range for singleton pregnancies, whereas estriol levels were normal in most cases. When one of the fetuses had died before week 33 of pregnancy (n = 5), both human placental lactogen and estriol levels were low and they were almost at the levels in singleton pregnancy. When intrauterine fetal death occurred after week 36 of pregnancy (n = 3), both hormone levels remained normal until term. Thus human placental lactogen rather than estriol is a good indicator of intrauterine growth retardation in twin pregnancy. Both human placental lactogen and estriol are useful for the monitoring of the surviving fetus in the case of single intrauterine fetal death.

Adult↗
PubMed1985

Effects of high ambient temperature on respiration rate, rectal temperature, fetal development and thyrold gland activity in tropical and temperate breeds of sheep.

The effects of high ambient temperatures on rectal temperature (RT), respiration rate (RR), fetal development and serum thyroxine (T(4)) concentrations were stuaied in two experiments involving 35 ewes and 26 lambs from the following ewe groups: 1) Barbados Blackbelly (B), a tropical breed; 2) Dorset (D), a temperate breed; and 3) Blackbelly x Dorset crosses (BxD). Data were obtained on four B, five D and five BxD ewes exhibiting estrus during the summer (Exp. 1). In Exp. 2, eight B, seven D and six BxD ewes were maintained in two environmental chambers (cool, 22.2C; hot, 33.8C) from day 125 of gestation to seven days before the expected lambing date for each breed group (D and BxD, 140+/-1; B, 144+/-1 day of gestation). The B and BxD ewes were more heat-tolerant than D ewes as measured by significantly lower RT and RR in each experiment. Mean lamb birth weight, crown-rump length, number of functional uterine caruncles and caruncle weight and size did not vary significantly among breed groups or temperature chamber (Exp. 2), and there was no indication that the high temperature imposed caused fetal dwarfing in lambs removed from the uterus at a standard age of seven days before expected parturition. Serum T(4) varied markedly among breed groups (P<0.05) in each experiment with B ewes having the lowest and BxD ewes the highest concentration. In Exp. 1, follicular stage T(4) concentrations in B and BxD ewes were lower (P<0.02) than those during the luteal stage of the estrous cycle. The decrease in D ewes was not significant. High ambient temperature (Exp. 2) depressed T(4) levels in D ewes (P<0.05) and also depressed the pituitary-thyroid response to thyrotropin releasing hormone in D lambs. Such was not the case in B and BxD ewes and their lambs.

Journal Article↗
PubMed1992

Fetal development of mice following intrauterine exposure to a static magnetic field of 6.3 T.

The study was undertaken to investigate possible teratogenic effects of a high magnetic field on fetal development in mice. Eighty-four pregnant CD-1 mice (ICR) were exposed to a static magnetic field of 6.3 T for 1 hr a day from day 7 through day 14 of gestation, a period corresponding to major organogenesis. Fifty mice served as controls. Dams were sacrificed on day 18 of gestation. Fetuses were examined for both external and skeletal abnormalities. No significant differences between exposed and control groups were observed regarding litter size, fetal weight, intrauterine mortality rate, or external and skeletal anomalies. The effects of static magnetic field of 6.3 T on the parameters studied appear negligible.

Animals↗
PubMed1989

[Role of disorders of pentosephosphate pathway of glucose oxidation in the pathogenesis of the arrest of fetal development in miscarriage].

Activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, the enzymes participating in the pentose phosphate pathway of glucose oxidation was studied in the blood of 15 normal fetuses and 25 abortuses as well as in 80 females (20 with normally advancing pregnancy, 40 with the signs of discontinuation and 20 patients with spontaneous abortion developed during 24-26 weeks of gestation). The impact of abnormal pentose phosphate pathway of glucose oxidation on the pathogenesis of fetal development arrest in females with incompetent pregnancy was established.

Abortion, Spontaneous↗
PubMed1987

Evaluation of the effects of inhalation exposure to 1,3-dichloropropene on fetal development in rats and rabbits.

1,3-Dichloropropene (DCP), which has found widespread use as a soil fumigant, was evaluated for its potential effects on embryonal and fetal development in rats and rabbits. Pregnant Fischer 344 rats and New Zealand White rabbits were exposed to 0, 20, 60, or 120 ppm of 1,3-dichloropropene for 6 hr/day during gestation Days 6-15 (rats) or 6-18 (rabbits). Exposure-related decreases in maternal weight gain and feed consumption were observed in rats at all treatment levels. Decreased weight gain was also observed among rabbits at 60 and 120 ppm. A slight, but statistically significant, increase in the incidence of delayed ossification of the vertebral centra in rats exposed in utero to 120 ppm of DCP was considered of little toxicologic significance in light of the maternal toxicity observed at this exposure concentration. No evidence of a teratogenic or embryotoxic response was observed in either species at any exposure level tested. Thus, it was concluded that DCP was not teratogenic at exposure levels up to 120 ppm in either rats or rabbits.

Aerosols↗
PubMed1999

Effects of an environmental endocrine disruptor on fetal development, estrogen receptor(alpha) and epidermal growth factor receptor expression in the porcine male genital tract.

PURPOSE: We studied the effect of a potent reproductive tract toxin, 2,3,7,8-tetrachlorodibenzo-rho-dioxin, on fetal development and expression of estrogen receptor alpha and epidermal growth factor receptor (EGFR) in male swine. MATERIALS AND METHODS: Fetal domestic swine and miniswine were injected with 1 microg./kg. dioxin on day 50 of gestation and removed near term (114 days). Germ cell counts were performed on sections of formalin fixed testes. Estrogen receptor a protein, and messenger ribonucleic acid (mRNA) and EGFR mRNA expression were analyzed in frozen tissue using Western blotting and semiquantitative reverse transcriptase polymerase chain reaction. RESULTS: Of 15 dioxin exposed male offspring 8 (53%) had genital anomalies, including cryptorchidism in 4, epididymal detachment in 1, epididymal atresia in 1 and vasal dilatation in 3, while 3 of 17 control male swine (18%) had incompletely descended testes (p = 0.06). High intra-abdominal testes were found in 3 of 4 cryptorchid dioxin exposed but no control male swine. Mean germ cell number per tubule was 4.0+/-1.1 and 2.7+/-0.7 in control and dioxin groups, respectively (p = 0.01). Estrogen receptor a protein and mRNA were identified in fetal uterus, testis, gubernaculum and epididymis. Protein levels were 2 to 3-fold higher in dioxin exposed testis, and mRNA levels were significantly lower in gubernaculum and epididymis. EGFR mRNA expression was similar in treated and control testis and epididymis. CONCLUSIONS: Preliminary data suggest that dioxin produces cryptorchidism and wolffian duct anomalies in male swine exposed just before mid gestation. Germ cell counts and estrogen receptor alpha mRNA expression in gubernaculum and epididymis were significantly reduced, and estrogen receptor a protein expression in testis appeared to be increased by dioxin exposure. Aberrant regulation of estrogen receptor a expression by dioxin may contribute to reproductive tract anomalies in male fetuses.

Animals↗
PubMed1991

Developing fetal alveolar epithelial cells secrete fluid in primary culture.

The developing pulmonary epithelium secretes a Cl(-)-rich fluid during fetal life by a process involving active transport. To determine if alveolar cells contribute to this fluid production, we studied developing fetal rat alveolar epithelial cells (18-day gestation) in primary culture. Fetal alveolar epithelial cells aggregated to form cystic, alveolar-like structures with a fluid-filled lumen. On light and transmission electron microscopy, the cells were polarized with microvilli facing the lumen. Dexamethasone and triiodothyronine stimulated lamellar body production in many of the epithelial cells of the cyst wall. The transepithelial voltage in the cyst was -2.4 +/- 0.4 mV (lumen negative), suggesting the presence of active electrolyte transport. Bumetanide, an inhibitor of Cl- secretion in other systems, decreased the size and number of cysts. A membrane-permeant analogue of adenosine 3',5'-cyclic monophosphate (cAMP) and 3-isobutyl-1-methylxanthine increased the size of cysts, an effect that was blocked by coincubation with bumetanide. The increased size of the cysts did not result from stimulation of cell growth; in fact, [3H]thymidine incorporation was inhibited to 40% control values by cAMP, suggesting that growth was inhibited rather than stimulated. These results suggest that fetal alveolar epithelial cells secrete fluid via a cAMP-mediated Cl(-)-secretory process. Secretion of fluid by the developing alveolar epithelium may play an important role in lung development.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Platelet-derived growth factors and growth-related genes in rat lung. III. Immunolocalization during fetal development.

To further study the role of platelet-derived growth factor (PDGF) in fetal lung development, the distribution of the PDGF homodimers PDGF-AA and PDGF-BB was examined by immunohistochemistry in embryonic and fetal rat lung from d 12 to 22 of gestation (term = 22 d). PDGF-AA and PDGF-BB were localized to airway epithelial cells as early as d 12 of gestation, 2 d before their appearance in mesenchymal cells. Both PDGF homodimer immunoreactivities increased until the late pseudoglandular stage of lung development, followed by fluctuations in reactivity during the canalicular stage. Only weak immunoreactivity to either PDGF homodimer was evident during the saccular stage of lung development. Immunodetection by Western blotting revealed that PDGF-AA and PDGF-BB homodimer protein concentrations were high during the embryonic and pseudoglandular stage of lung development and decreased with advancing gestation. We conclude that the presence of PDGF in both developing airway epithelial cells and mesenchymal cells, as well as gestation-dependent changes of PDGF homodimers, is compatible with a role for this growth factor during fetal lung development.

Animals↗