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At least 991 records · Page 55Linked to original sources
PubMed1987

Birth weight distribution as an indicator of environmental effects on fetal development.

A medical birth registry was used for a geographical analysis of birth weight distribution. Nearly 900,000 Swedish singleton births, 1973-1981, were used for an analysis of the effect of some variables and for standardization for these variables. A marked change in the rate of low birth weight infants (LBW, less than 2,500 g) was seen in the country between 1976 and 1977. A U-formed effect of maternal age and of parity was demonstrated. A marked interaction between the effects of these two variables existed. Two social groups were compared and the well-known high rate of LBW infants associated with low socioeconomic conditions was demonstrated. Standardization for the variables mentioned influenced this effect only little but reduced the difference between the social groups concerning infants above 3.5 kg weight. The background data were used for analysis of restricted geographical areas.

Adult↗
PubMed1986

Thyroid hormone opposes some glucocorticoid effects on glycogen content and lipid synthesis in developing fetal rat lung.

Because of current interest in use of a combination of glucocorticoid and thyroid hormones for prevention of respiratory distress syndrome we examined the effects of dexamethasone and triiodothyronine (T3), alone and in combination, on glycogen content and rates of fatty acid and phosphatidylcholine synthesis in fetal rat lung. The hormones were administered to the mothers on the 2 days before delivery on days 17-22 of gestation. Both hormones increased the rate of choline incorporation into phosphatidylcholine, an index of surfactant synthesis, on day 20 just prior to the normal developmental surge but had no effect on this parameter on days 19, 21, or 22. There is a developmental increase in lung glycogen on days 17-20 with a decrease thereafter and a developmental increase in the rate of fatty acid synthesis between days 20 and 21. The increases in glycogen content and fatty acid synthesis were accelerated by dexamethasone and prevented by T3 and when the hormones were administered together T3 antagonized the stimulatory effects of dexamethasone on these parameters. Both dexamethasone and T3 accelerated the normal developmental decrease in lung glycogen later in gestation and the effects of the two hormones on this parameter were additive. The combination of dexamethasone and T3 led to significantly smaller fetuses and increased mortality late in gestation. These data show that glucocorticoid and thyroid hormones have opposite as well as common effects on parameters of fetal lung maturation. Although the relationship between changes in lung glycogen or fatty acid synthesis and surfactant production are not known the combination of hormones may be beneficial at certain gestational ages but harmful at others.

Animals↗
PubMed1976

Levels of testosterone in the plasma, gonads, and adrenals during fetal development of the rabbit.

Testerone (T) concentrations in the plasma, gonads, and adrenals were measured by radioimmunoassay in 188 male and 160 female rabbit fetuses. Determinations were performed daily from the 20th to the 31st day of gestation and were correlated with the maternal plasma concentration of T. The T content of both testes remained relatively constant from the 20th (3040 pg) to the 26th day (3940 pg), and subsequently decreased until the 31st day (1630pg). the concentration of testicular T fluctuated only slightly from the 20th (1040 pg/mg) to the 23rd day (783 pg/mg), and thereafter decreased until the 31st day (138 pg/mg). The T levels in plasma of males (132-361 pg/ml) were significantly higher than those of females (21-116 pg/ml). Plasma T levels in males were relatively constant and did not exhibit any rise, which is similar to observations of the testis during differentiation of the genital tract. Testosterone concentrations were low in the adrenals (3.5-12.3 pg/mg) of both sexes and in the ovaries (1.5-20.4 pg/mg) of fetuses. These data provide the first evidence for testicular T secretion at the time of genital differentiation in the rabbit.

Adrenal Glands↗
PubMed1996

The sites of gene expression of atrial, brain, and C-type natriuretic peptides in mouse fetal development: temporal changes in embryos and placenta.

Atrial (ANP), brain (BNP), and C-type natriuretic peptide (CNP) belong to a family of hormones important in blood pressure and sodium homeostasis. Expression of ANP has been reported in embryo hearts, but BNP and CNP expression during development has not been described. We used in situ hybridization to identify the sites of gene expression of ANP, BNP, and CNP during development in mouse embryos at daily intervals from midgestation. Very intense expression of ANP and BNP was visible in the heart from 9.5 days gestation; levels of expression of both peptides in the ventricle exceeded those in atria throughout gestation. There was a major peak of atrial and ventricular ANP and BNP expression at 12.5 days, attaining levels similar to those in adult heart and then declining until birth. Cardiac expression of CNP was undetectable. Expression of ANP and CNP was also observed in distinct sites in the brain, and all three peptides were expressed in the spinal cord. In mouse placenta, strong CNP expression was seen in the decidua basalis around the large maternal blood vessels, and BNP message was detected at the peripheral margin of the decidual layer. This pattern of expression indicates that ANP and CNP are present during development of the mouse central nervous system and suggests that CNP and BNP participate in regulating the maternal blood supply to the developing embryo.

Animals↗
PubMed1976

Effects of superovulation on fetal development and hormone levels in the pregnant hamster.

Treatment of hamsters with 30 i.u. PMSG induced ovulation of 46 ova/animal, 90% of which were fertilized. CL growth was normal. About 27 zygotes/animal implanted and at term (Day 16) the litter size of the PMSG-treated hamsters was 21 compared to the normal number of 10. Parturition occurred at the normal time. Average weight at birth was about 500 mg less for young of PMSG-treated mothers than for controls. Differences were found in the serum progesterone and oestradiol concentrations of the treated and control hamsters, but serum FSH and LH levels were similar.

Animals↗