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PubMed1989

Fetal development.

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Embryo, Mammalian↗
PubMed1992

Efficacy of first trimester transvaginal sonography in detecting normal fetal development.

The transvaginal probe is now commonly used by the obstetrician/gynecologist. The improved resolution offered by the probe makes it easier to study the anatomic development of the first trimester fetus in greater detail. The aim of this study was to define the gestational age at which certain fetal structures become apparent by ultrasound and to screen pregnancies at high risk for development of fetal anomalies that could be detected in the first trimester. Endovaginal ultrasound was performed on 60 pregnant women at 8 to 13 menstrual weeks. Clinical follow-up disclosed 36 normally developed fetuses at delivery, five abnormal scans, and 19 ongoing pregnancies. The results of this study show that it is possible to demonstrate most of the major fetal structures by 13 weeks' gestation. By imaging the fetus transvaginally, detection of fetal anomalies can be accomplished much earlier than with the transabdominal scanning alone.

Adult↗
PubMed2000

Fetal haemodynamic changes in fetuses during fetal development evaluated by arterial pressure pulse and blood flow velocity waveforms.

OBJECTIVE: To study the relation between diameter pulse (pressure pulse) and flow velocity waveforms in the fetal descending aorta in fetuses with intrauterine growth retardation and acceleration. DESIGN: Blood flow through a tubular system can be expressed by the ratio of blood pressure to vascular resistance. Doppler ultrasound and a phase locked loop echo tracking system coupled to a B-mode ultrasonic imager (central frequency 3.5 MHz) were used to assess downstream resistance and change in blood pressure, respectively. SETTING: Tertiary referral unit in a teaching hospital PARTICIPANTS: Serial study between 21 and 40 weeks of 22 women with normally grown fetuses at intervals of four weeks; 25 women with small for gestational age fetuses with uteroplacental insufficiency (high umbilical artery pulsatility index); and six women with large for gestational age fetuses. MAIN OUTCOME MEASURES: We measured the maximum systolic and minimum diastolic diameter of the fetal descending aorta (the pulse amplitude) and then calculated the pulsatile waveform time integral above the least diastolic diameter (pulsatile area) and total waveform time integral (perfusion area). RESULTS: Normal fetal growth was associated with an increase in systolic and diastolic diameters in the fetal descending aorta with advancing gestational age. Pulse amplitude, pulsatile and perfusion areas increased with gestational age. The increased pulse amplitude and increased pulsatile area in association with a decrease of the pulsatility index in the descending aorta during the second trimester suggested that pulse pressure and stroke volume were increased. In the group with intrauterine growth retardation, systolic and diastolic diameters of the descending aorta and perfusion area were within the normal range. Moreover, there was an increase in the diastolic diameter per unit fetal weight and a decrease in the pulsatile area. In the large for gestational age fetuses, there was an increase in the pulse amplitude and pulsatile area. CONCLUSION: These findings suggest that in growth restricted fetuses there is an increase in diastolic pressure and a reduction in stroke volume, while in large for gestational age fetuses there is an increase in the pulse pressure and stroke volume. It is possible that measurement of pressure pulse waveform in relation to Doppler velocity waveform may be used to infer changes of blood flow.

Blood Flow Velocity↗
PubMed1989

Amniotic oxytocin and vasopressin in relation to human fetal development and labour.

Previous experiments in rats revealed increased amniotic oxytocin (OXT) levels in the course of normal development and increased vasopressin (AVP) levels in retarded fetal growth. In order to see whether similar changes would also occur in human, OXT and AVP levels were determined in amniotic fluid, maternal and fetal plasma before or during labour. Positive correlations were found between umbilical AVP levels on the one hand and gestation length, birth weight, placental weight and brain size on the other. This suggests a maturation process taking place in the AVP-producing system. A marked increase in maternal plasma OXT and umbilical AVP was found during labour. Increased amniotic fluid AVP levels were found in conditions indicative of fetal stress (viz., lower pH, higher PCO2) without any correlation to fetal growth parameters, while increased amniotic OXT levels were correlated with higher PO2. Furthermore, fetal brain size correlated positively with amniotic OXT levels. In conclusion, a rise in amniotic OXT levels seems to reflect normal development of the human fetus, similarly to what has been found in the rat. Increased amniotic AVP levels seem indicative of fetal acidosis.

Acid-Base Equilibrium↗
PubMed2003

Fetal development after assisted reproduction--a review.

Despite the success of assisted reproduction technologies (ART) in allowing conception in couples with infertility problems, a growing body of evidence points to implication of ART on fetal birth weight alterations, fetal malformations, chromosomal aneuploidies and syndromes related to genomic imprinting modifications. Different causes can be accounted for to explain the increased risk of fetal defects. Pregnancies generated by ART differ from spontaneously achieved pregnancies in that gametes and embryos are cultured in vitro, more than one conceptus is transferred into the uterine cavity, and the time of transfer is different to what occurs in normal conditions. Epigenetic reprogramming of gene expression has been advocated in relation to the gamete and embryo manipulation, with a significant role of genomic imprinting in determining changes in fetal growth. Moreover, the maternal environment, with the ovarian hyperstimulation of the beginning of pregnancy, could alter the maternal response to the early phases of trophoblast invasion. There are suggestions that placental weights and placental/fetal weight ratios are increased in these pregnancies resembling the model of maternal undernutrition in the early phases of pregnancy. Therefore concern has also arisen around the possible long term and transgenerational effects of assisted reproduction procedures and studies should be carried out to evaluate these possibilities.

Adult↗
PubMed1983

Colonic mucus in human fetal development.

The labelling behaviour of specimens of human fetal colon at different stages of development was examined using eight fluorescently labelled lectins with preferences for different carbohydrate structures. Peanut agglutinin (PNA) binding can be demonstrated in specimens from fetal colons between the 4th and 5th week and the 5th and 6th lunar month. Since CEA may bind to similar structures as PNA, an answer was sought to the question whether these structures are in fact identical. While there is evidence in favour of non-identity, it is not entirely conclusive. PNA-binding to fetal tissues is of interest since PNA binds to adult transformed colonic tissues, but not to normal ones.

Antigens, Neoplasm↗
PubMed2004

Expression of fibroblast growth factors 18 and 23 during human embryonic and fetal development.

Fibroblast Growth Factor (FGF) 18 and 23 are two recently identified members of the FGF family, a family of structurally related polypeptides with diverse roles in physiological and pathological processes. Studies mostly performed in rodents and chicken have demonstrated that FGF18 is a pleiotropic growth factor involved in the development of various organs, while there are no data supporting a direct role of FGF23 in cell proliferation or differentiation either in physiology or pathology in any species. However, it is now established that FGF23 can be a humoral messenger and an important regulator of phosphate homeostasis and vitamin D metabolism. As a first step towards elucidating the roles of these FGF in human development, we examined FGF18 and FGF23 mRNA expression by in situ hybridization in whole human embryos at 30 days and 8 weeks of gestation (GW) and in specific fetal tissues at different ages. We report a highly restricted expression pattern for both FGF genes in human embryonic development.

Cell Differentiation↗
PubMed2003

The effects of maternal age and parity on placental and fetal development in the mare.

REASONS FOR PERFORMING STUDY: The normality of equine placentation is essential for fetal health and development. Substantial information exists on the gross morphological status of the placenta but few studies have addressed the problem of degenerative lesions that interfere with placental morphology and placental efficiency. HYPOTHESIS: Degenerative changes in the endometrium with increasing age and parity are reflected in the morphology and density of the placental microcotyledons. OBJECTIVE: To assess placental efficiency on the basis of foal birthweight as a function of total microscopic area of fetomaternal contact. METHODS: Stereology was used to examine the placentae of 84 Thoroughbred mares grouped on the basis of age and parity. Placental efficiency, assessed by expressing foal birthweight as a function of total microscopic area of fetomaternal contact, was also determined. RESULTS: Mare age and parity influenced the development of the microcotyledons and microcotyledon surface density (Sv) was lowest in aged multiparous mares, presumably due to degenerative changes in their endometrium. However, primiparous mares also showed significantly lower Sv values than young multiparous mares, despite the virginal endometrium of the former group. This apparent 'priming' effect of a first pregnancy on microcotyledonary Sv was illustrated further by 11 maiden mares followed in 2 successive pregnancies. They all showed significant increases in Sv values in their second parity, with equivalent improvements in foal birthweight. CONCLUSIONS: Foal birthweight is a reflection of the balance between fetomaternal contact and placental efficiency. Increases in fetomaternal contact are correlated to reductions in placental efficiency, which may reflect the ability of the placenta to modify its exchange capabilities. POTENTIAL RELEVANCE: Further work is needed to elucidate how such changes in microcotyledon morphology and efficiency are brought about.

Age Factors↗