Gestational Data Research Articles

Persistent short stature, other potential outcomes, and the effect of growth hormone treatment in children who are born small for gestational age.

Persistent short stature, other potential outcomes, and the effect of growth hormone treatment in children who are born small for gestational age.

Biologic Limits of Viability

After completing this article, readers should be able to: 1. Define the gestational range for extremely preterm birth. 2. Explain the difference between possibility and probability in reference to survival following extremely preterm birth. 3. Describe the key lung development required for adequacy of gas exchange. 4. Describe the renal functional limitations for water, sodium, and creatinine homeostasis in the first postnatal week of the extremely preterm infant. 5. List at least one structural and/or functional limitation of at least five organ systems that increases mortality risks for the extremely preterm infant. With the advent of neonatal intensive care in the 1960s, preterm infants born at progressively lower gestational ages began to survive. The progression of the decrement did not follow a recognizable relationship; rather, it was erratic as the knowledge base of neonatal physiology and pathology expanded and new technical capabilities for life support were developed. The most dramatic increase in survival of extremely preterm birth (<26 completed weeks’ gestation) came with the introduction of surfactant replacement therapy in the late 1980s. The increased use of maternal antenatal corticosteroid therapy for induction of lung maturation with threatened preterm delivery following the National Institute of Child Health and Human Development Consensus Conference recommendations in 1994 also contributed to improved survival. Since that time, the survival of infants of gestational ages as low as 22 weeks’ has been reported. The purpose of this article is to review the current understanding of the biologic factors limiting survival potential, particularly as they inform clinical decision-making. Viability or survival potential, when used in reference to a fetus, frequently is used to indicate the possibility for a fetus to be live born and capable of living to a specified endpoint of either a designated time, reaching a certain age or a landmark event, admission to a neonatal intensive care unit, …

Exposure to air pollution during different gestational phases contributes to risks of low birth weight.

Although there have been growing concerns about the adverse effects of air pollution on birth outcomes, little is known about which specific exposure times of specific pollutants contribute to low birth weight (LBW). We evaluated the relationships between LBW and air pollution exposure levels in Seoul, Korea. Using the air pollution data, we estimated the exposure during each trimester and also during each month of pregnancy on the basis of the gestational age and birth date of each newborn. Generalized additive logistic regression analyses were conducted considering infant sex, birth order, maternal age, parental education level, time trend, and gestational age. The monthly analyses suggested that the risks for LBW tended to increase with carbon monoxide (CO) exposure between months 2-5 of pregnancy, with exposure to particles <10 micro m (PM(10)) in months 2 and 4, and for sulphur dioxide (SO(2)) and nitrogen dioxide (NO(2)) exposure between months 3-5. This study suggests that exposure to CO, PM(10,) SO(2) and NO(2) during early to mid pregnancy contribute to risks for LBW.

Compromise ultrasound dating policy in maternal serum screening for Down syndrome.

Routine ultrasound biometry is the method of choice for gestational dating when screening for Down syndrome. However, it is costly and an alternative policy is to restrict ultrasound to women most likely to have menstrual dating errors. This was evaluated by statistical modelling with parameters from 14,274 women screened between January 1997 and July 2001 using free beta-human chorionic gonadotrophin (free beta-hCG), alpha-fetoprotein (AFP) and unconjugated estriol (uE(3)). A total of 12,711 (89%) women had both ultrasound and menstrual gestations, but in 4101 (29%) women either the last menstrual period (LMP) was uncertain or a pill-withdrawal period, or there were irregular or abnormal length cycles. The LMP was not entered in the test request form for a further 1404 (9.8%) women. Routine ultrasound dating yielded a predicted detection rate higher than for menstrual dating by 3.9-7.1%, depending on the marker combination and cut-off. The false-positive rate was reduced by 0.2-1.1%. Selectively scanning the 39% with unreliable dates increased detection by 2.6-4.6%, and reduced the false-positive rate by 0.04-0.6%. Some centres only use the ultrasound estimate of gestation when it differs from the menstrual estimate by more than 7 days. Such a rule reduces the gain in detection rate to 2.5-4.6% for routine ultrasound and 1.7-3.1% with the compromise policy; the false-positive rate reductions are 0.06-0.6% and 0.0-0.3%, respectively. We conclude that if routine ultrasound is not financially and practically feasible, the compromise policy yields a clinically important improvement in screening performance compared to menstrual dating.

Détresse respiratoire, corticothérapie postnatale précoce et leucomalacie périventriculaire

The aetiology of cavitating periventricular leukomalacia (cPVL) involves pre and perinatal factors. Early postnatal dexamethasone has been associated with an increase in cerebral palsy but its role in the development of PVL remains uncertain. Objectives. – (1) Reevaluate major factors associated with cPVL, (2) Evaluate the potential effect of early postnatal dexamethasone. Method. – This retrospective case-control study (matched for gestational age, birth weight, twin pregnancy and date of birth) compared 50 premature infants with cPVL diagnosed between D7 and D45 from 1995 to 2000 and 50 matched control newborns with normal serial neurosonograms. A data base with 97 selected perinatal variables was used to perform logistic regression analysis in controlling confounding variables, the results are expressed as adjusted Odds Ratio (OR) with 95% confidence interval. Results. – The two populations were comparable for gestational age (median: 29.3 weeks, range: 24,4 –34,7) and birth-weight (1297 g, 645 –2130 g). The annual incidence of cPVL in preterm infants with a gestational age < 33 weeks varied from 1995 to 2000 : 1.3%, 4.5%, 13.4%, 2.1%, 3%, 2.9%. Early postnatal dexamethasone was used in 23 of the newborns who developed cPVL (between november 1996 and march 1998). The only antenatal factor associated with cPVL was cardiac decelerations (28% vs 14%, OR = 3.4, 1.1 –11,3). The postnatal risk factors were respiratory distress syndrome requiring the use of rescue surfactant (78% vs 38%, OR = 4,2, 1.4 –11,9) and early postnatal dexamethasone at the time it was used (78% vs 17%, OR = 17,1, 3,9 –73). Conclusion. – The use of rescue surfactant and of early postnatal dexamethasone in preterm infants with respiratory distress syndrome were independently associated with the subsequent occurrence of cPVL. Cardiac deceleration was the only antenatal factor associated with cPVL.

Lung maturation in diabetes in pregnancy: If and when to test

Poorly controlled maternal diabetes in pregnancy may delay fetal pulmonary maturation. However, diabetic women with good glycemic control have fetal lung maturation at the same gestational age as nondiabetic women. With modern ultrasound technology, gestational dates can be accurately assessed in the first or early second trimester. Respiratory distress syndrome is rare in nondiabetic and well-controlled diabetic pregnancies confirmed by early ultrasound to be at or beyond 37 weeks. Early confirmation of dates thus eliminates the need for amniotic fluid assessment of fetal lung maturity prior to elective delivery at or beyond 38 weeks in well-controlled diabetic and nondiabetic women. Poorly controlled diabetic women and pregnancies without early ultrasound verified dates may require amniotic fluid analysis for lung maturity prior to elective delivery.

Ultrasonic measurements of second and third trimester fetuses to predict gestational age and date of parturition in captive and wild spotted hyenas Crocuta crocuta

Parturition in spotted hyenas ( Crocuta crocuta) is a fascinating event to witness, as females of this species are highly masculinized and give birth through a penis-like clitoris. Furthermore, shortly after birth, a high rate of aggression occurs between littermates that can sometimes end in siblicide. To study these events thoroughly, an accurate estimate of the date of parturition is necessary. To this end, we performed transabdominal ultrasounds every 20–30 days in five captive spotted hyenas of known gestational age, beginning approximately 30 days after mating. We measured the femur length (FL), abdominal circumference (AC), and biparietal diameter (BPD) of eight fetuses from Days 42 to 100 of their 110 days of gestation. FL proved to be the most effective measurement, as it correlated well with gestational age and was easy to obtain consistently. The relationship between estimated gestational age (EGA) and FL is described by the equation: [EGA=37.3+(14.0×FL)]. AC also correlated well with EGA, but was more difficult to measure than FL. Measuring BPD became increasingly difficult as pregnancies advanced beyond 70 days of gestation. Because gestational age is often not known in captive and free-ranging spotted hyenas, measuring fetal FL ultrasonographically is a rapid and reliable way to determine an approximate date of parturition. This technique proved invaluable when used to track and monitor a free-ranging spotted hyena during the days just before and after parturition.

Elevated plasma homocysteine in early pregnancy: A risk factor for the development of severe preeclampsia

Objective: The aim of our study was to determine if an elevated plasma homocysteine level in early pregnancy is associated with the development of severe preeclampsia. Study Design: Blood samples were obtained from patients attending their first antenatal visit. Cases were asymptomatic women who subsequently developed severe preeclampsia. Controls were matched for gestational age and date of sample collection. Plasma homocysteine level was measured by using fluorescence polarization immunoassay. Results: There were 56 patients with severe preeclampsia from whom blood samples were obtained at a mean (±SD) gestation of 15.3 weeks (±4.04 weeks) and 112 controls at 14.9 weeks (±3.41 weeks). The preeclampsia cases had a mean (±SD) homocysteine level of 9.8 μmol/L (±3.3 μmol/L), whereas controls had a mean homocysteine level of 8.4 μmol/L (±1.9 μmol/L), P ≤.0001. Conclusion: Women who develop severe preeclampsia have higher plasma homocysteine levels in early pregnancy than women who remain normotensive throughout pregnancy. An elevated plasma homocysteine level in early pregnancy can increase the risk of developing severe preeclampsia by almost threefold. (Am J Obstet Gynecol 2001;185:781–5.)

Factors Influencing Fetal Growth

After completing this article, readers should be able to: 1. Describe the roles of insulin-like growth factor on fetal growth and development. 2. Delineate components of “maternal constraint.” 3. Explain the role of the placenta in regulating fetal growth. 4. Describe the effects of fetal glucose, amino acid, and fat supply on fetal growth. The principal determinants of fetal growth are fetal genotype and in utero environment. Environmental factors include maternal and paternal genetics, maternal size, and the capacity of the placenta to provide nutrients to the fetus. These environmental factors interact with the intrinsic growth pattern of the fetus, yielding a particular rate and composition of fetal growth. Most of the variation in fetal growth in a population is due to variations in environmental factors, not the fetal genome, although a genetically abnormal fetus clearly might not grow as well as a normal fetus if affected genes include those that are important for growth. Many genes contribute to fetal growth and birthweight. Techniques in which specific genes can either be deleted (“knockouts”) or overexpressed have led to greater understanding of how some of these genes regulate fetal growth. Such studies have shown that both maternal and paternal influences are present during fetal development and are passed on to the developing fetus by spermatozoa or oogonia by a mechanism called imprinting. Although the maternal genetic composition exerts greater influence than fetal genotype in the overall regulation of fetal growth, both maternal and paternal genomes are important in fetal growth and development (1)(2). For example, gynogenetic zygotes (two maternal genome copies) lead to underdeveloped extraembryonic tissues but well-developed embryos. The more modest regulation offered by the paternal genotype is essential for trophoblast development. For example, zygote nuclear transfer experiments have shown that androgenetic zygotes (two paternal genome copies) develop extensive trophoblast tissues but …

Neonatal and neurodevelopmental outcome in infants born before 30 weeks of gestation with absent or reversed end-diastolic flow velocities in the umbilical artery.

The objective of our study was to examine the outcome of infants born at a gestational age < 30 weeks with absent or reversed end-diastolic flow velocity (AREDFV) in the umbilical artery in comparison with gestational age-matched eutrophic controls. A group of 40 infants who had AREDFV were matched for gestational age and date of birth with 40 appropriate for gestational age infants. Perinatal outcome variables were retrospectively reviewed. In 16 out of the 40 matched pairs, a standardized neurological examination was done and, depending on age, the Kaufman Assessment Battery for Children or the Bayley Scales of Infant Development were applied at a corrected age of 13 to 100 months to assess neurodevelopmental outcome. The results were compared using Fisher's Exact Test or Mann Whitney U Tests as appropriate. In the AREDFV group, 26/40 (65%) survived until discharge compared to 39/40 (97.5%) in the control group (P < 0.001). AREDFV was associated with a higher rate of chronic lung disease, retinopathy of prematurity > or = grade III and impaired intestinal motility. More AREDFV infants suffered from permanent neurological sequelae compared with control infants: 44% versus 25% were mentally retarded (P = 0.033), and 38% versus 19% showed severe motor impairment (P = 0.073). Absent or reversed end-diastolic flow velocity is not only associated with a higher mortality and morbidity during the neonatal period, but the surviving infants of this high risk group have an increased risk for mental retardation and severe motor impairment as compared with appropriate for gestational age preterm infants of the same gestational age.

Maternal life history--versus gestation-focused assessment of prenatal exposure to substances of abuse.

Substance use by pregnant women is socially stigmatized and may be legally punishable. This societal condemnation raises concerns about underascertainment of prenatal substance exposure of offspring if mothers are asked specifically about their behavior during gestation, versus their life histories without reference to gestational dates. This study assessed agreement between life history-focused and pregnancy-focused assessments of prenatal exposure, and percentages of offspring classified as exposed to a range of substances by each measure, in a sample of school-aged children of methadone-maintained, opioid-dependent parents. Prenatal exposure was assessed in 172 offspring of 109 mothers by: (a) questionnaires administered to mothers about substance use during pregnancy; and (b) best-estimate (BE) diagnoses of substance use disorders in mothers overlapping with pregnancy dates. BE diagnoses were based on interviews with the Schedule for Affective Disorders and Schizophrenia-Lifetime Version, conducted by trained mental health professionals with mothers about their life histories of psychiatric and substance use disorders, as well as mothers' medical records. Chance-corrected agreement between the measures was examined using kappa statistics. Percentages of offspring classified as exposed by each method were compared using McNemar chi 2 tests. Except for cigarettes, agreement between the measures was poor. Except for alcohol, diagnosed episodes of substance use disorders in mothers with dates overlapping pregnancy classified more offspring as exposed than mothers' responses to the questionnaire focusing on behavior while pregnant, though the differences in proportions identified as exposed were not always large or statistically significant. When retrospective ascertainment of prenatal exposure is necessary, asking mothers for their own life histories, without reference to pregnancy dates, may be the preferred approach.

The roles of clinical assessment, human chorionic gonadotropin assays, and ultrasonography in medical abortion practice

The clinical assessment of patients who request early medical abortion includes confirmation of the diagnosis of pregnancy and estimation of gestational age. Accurate gestational dating is essential, because the efficacies of medical abortion regimens decline as pregnancy advances. Whereas medical abortion researchers in the United States have relied on routine ultrasonography for gestational dating, abortion providers experienced with mifepristone and prostaglandin regimens outside the United States have reported high efficacy and safety primarily with clinical dating parameters. Diligent follow-up of patients allows clinicians to confirm that complete abortion has occurred without complications. In cases of uncertain outcome or suspected ectopic pregnancy, transvaginal ultrasonography and β-human chorionic gonadotropin assays can assist in prompt diagnosis and management. As medical abortion with mifepristone and misoprostol becomes more prevalent in the United States, studies will be needed to further evaluate the effects of these modalities on medical abortion outcomes. (Am J Obstet Gynecol 2000;183:S34-S43.)

Myomectomy during Early Pregnancy

Abdominal pain during early pregnancy may be caused by leiomyoma of the uterus. Inconsistency of uterine size and gestational dates in a pregnant patient with acute abdominal pain may be the first sign of leiomyoma. This 31-year-old primigravida presented with progressively worsening lower abdominal pain at 12 weeks gestational age. Ultrasonography and magnetic resonance imaging demonstrated a large fundal heterogeneous mass and an intrauterine gestation compatible with her menstrual dates. Exploratory surgery and myomectomy confirmed a large leiomyoma showing benign degenerative changes. The operative procedure was successful, and the pregnancy progressed normally. An elective cesarean section was performed at 37 weeks gestation after confirming fetal maturity by amniocentesis and serial ultrasonography. Abdominal pain in a pregnant patient with leiomyoma uteri may be attributable to degenerative changes in the myoma. Surgical intervention during pregnancy is occasionally necessary in uncommon cases of intractable pain.

The prediction of adverse pregnancy outcome using low unconjugated estriol in the second trimester of pregnancy without risk of Down's syndrome.

To investigate the relationship between low unconjugated estriol (uE3) levels in the second trimester and adverse perinatal outcomes in pregnancies without increased risk for Down's syndrome, 1,096 women under 35 years of age underwent a mid-trimester AFP-hCG-uE3 screening test between January 1995 and June 1998. Multiple pregnancies, maternal diabetes, smoking and elevation of AFP and hCG levels more than 2.0 multiple of median (MoM) were excluded from our study population. The results were divided into a low-uE3 group with uE3 levels at or below 0.75 MoM and a normal uE3 group with uE3 levels above 0.75 MoM. The risk for adverse pregnancy outcome was compared between the two groups and the role of low uE3 as a predictor of adverse pregnancy outcome was determined. The data were assessed using chi 2 or Fisher exact test and then logistic regression was used for the final analysis. The odds ratio (OR) and corresponding 95% confidence intervals (CI) were also calculated. Unconjugated E3 levels at or below 0.75 MoM was significantly associated with fetal growth restriction after adjustment for maternal age, weight, sampling weeks, AFP and hCG levels (OR 0.413, 95% CI 0.174-0.900; P = 0.035). Low uE3 levels in the second-trimester could help in the detection of fetal growth restriction by a low risk group in Down's syndrome. Careful gestational dating and serial clinical and sonographic assessment of fetal growth may be required for the clinician to manage these parturients.

Neurogenesis of galanin cells in the bed nucleus of the stria terminalis and centromedial amygdala in rats: A model for sexual differentiation of neuronal phenotype

Male rats possess twice as many cells that express arginine-vasopressin (AVP) in the bed nucleus of the stria terminalis (BST) and centromedial amygdala (CMA) as do females. This sex difference may arise from sex differences in the induction of AVP expression in galanin (GAL)-expressing cells, which themselves do not differ in number between males and females. To test whether AVP expression could arise from a single pool of galaninergic cells, we determined whether the cell birth profile of GAL-immunoreactive (ir) cells was similar to that of AVP-ir cells. Dams were injected with the cell birth marker bromodeoxyuridine (BrdU) on one of seven gestational dates, ranging from embryonic day 11 (E11) to E17. The resulting offspring were sacrificed at 3 months of age. Processing their brains for the presence of either GAL and BrdU, or AVP and BrdU immunoreactivity revealed that in both the BST and CMA, the majority of GAL-ir and AVP-ir cells were labeled with BrdU on E12 and E13. In contrast, most other cells in the same region were labeled on E14 and E15. The similarity in the timing of cell birth of the GAL-ir and AVP-ir cells is consistent with the idea that GAL-ir cells in the BST/CMA constitute a single pool of cells that may be induced to express AVP during development. © 1999 John Wiley & Sons, Inc. J Neurobiol 38: 491–498, 1999

Neurogenesis of galanin cells in the bed nucleus of the stria terminalis and centromedial amygdala in rats: A model for sexual differentiation of neuronal phenotype

Male rats possess twice as many cells that express arginine-vasopressin (AVP) in the bed nucleus of the stria terminalis (BST) and centromedial amygdala (CMA) as do females. This sex difference may arise from sex differences in the induction of AVP expression in galanin (GAL)-expressing cells, which themselves do not differ in number between males and females. To test whether AVP expression could arise from a single pool of galaninergic cells, we determined whether the cell birth profile of GAL-immunoreactive (ir) cells was similar to that of AVP-ir cells. Dams were injected with the cell birth marker bromodeoxyuridine (BrdU) on one of seven gestational dates, ranging from embryonic day 11 (E11) to E17. The resulting offspring were sacrificed at 3 months of age. Processing their brains for the presence of either GAL and BrdU, or AVP and BrdU immunoreactivity revealed that in both the BST and CMA, the majority of GAL-ir and AVP-ir cells were labeled with BrdU on E12 and E13. In contrast, most other cells in the same region were labeled on E14 and E15. The similarity in the timing of cell birth of the GAL-ir and AVP-ir cells is consistent with the idea that GAL-ir cells in the BST/CMA constitute a single pool of cells that may be induced to express AVP during development.

Necrotising enterocolitis: is there a relationship to specific pathogens?

Outbreaks of necrotising enterocolitis (NEC) have often been related to specific pathogens such as Enterobacteriaceae. This relationship, however, remains uncertain because of the retrospective nature of the studies addressing this issue. We performed a prospective study to investigate whether there is indeed an association between NEC and specific pathogens. Between April 1993 and March 1997, stools of neonates of < 36 weeks admitted to our neonatal unit were investigated for bacteria in weekly intervals. Clinical and bacteriological data from each infant who developed NEC were compared with those from two control infants matched for gestational age and date of admission. Eighteen infants developed 19 episodes of NEC (clinical signs + air in portal vein); 8 of these had laparotomy; two died. Occurrences of NEC were homogeneously distributed over the 4-year study period. The only significant differences in the clinical course prior to NEC were a more severe stage of respiratory distress syndrome [median 2 (0-4) vs. 0 (0-3), P < 0.05] and a higher proportion of infants who had only been formula fed (63 vs. 32%, P < 0.05) in the cases. Within the last week prior to NEC, potentially pathogenic bacteria were identified in stools of all cases and 79% of controls (P < 0.05). However, there was no significant difference in the occurrence of specific pathogens or groups of pathogens in cases compared with controls. Although gut colonisation with potential pathogens appeared to be a prerequisite for the development of NEC, there were no specific bacteria associated with this disease if data from infants with NEC were compared with those from time- and gestational age-matched controls.

The Effect of Ambient Carbon Monoxide on Low Birth Weight among Children Born in Southern California between 1989 and 1993

We evaluated the effect of carbon monoxide (CO) exposures during the last trimester of pregnancy on the frequency of low birth weight among neonates born 1989-1993 to women living in the Los Angeles, California, area. Using birth certificate data for that period, we assembled a retrospective cohort of infants whose mothers resided within 2 miles of 1 of 18 CO monitoring stations. Based on the gestational age and birth date of each child, we estimated last-trimester exposure by averaging the corresponding 3 months of daily CO concentrations registered at the monitoring station closest to the mother's residence (determined from the birth certificate). Where data were available (at 6 stations), we also averaged measurements taken daily for nitrogen dioxide and ozone and those taken at 6-day intervals for particulate matter [less than/equal to]10 microm (PM10) to approximate last-trimester exposures to other pollutants. Overall, the study cohort consisted of 125,573 singleton children, excluding infants born before 37 or after 44 weeks of gestation, those weighing below 1,000 or above 5,500 g at birth, those for whom fewer than 10 days of CO measurements were available during the last trimester, and those whose mothers suffered from hypertension, diabetes, or uterine bleeding during pregnancy. Within the cohort, 2,813 (2.2%) were low in birth weight (between 1,000 and 2,499 g). Exposure to higher levels of ambient CO (&gt;5.5 ppm 3-month average) during the last trimester was associated with a significantly increased risk for low birth weight [odds ratio (OR) = 1.22; 95% confidence interval (CI), 1.03-1.44] after adjustment for potential confounders, including commuting habits in the monitoring area, sex of the child, level of prenatal care, and age, ethnicity, and education of the mother.

Expression of CDKI P27 Kip1 in malignant and non-malignant trophoblastic cells

Summary The cyclin-dependent kinase inhibitors (CDKIs) inhibit the kinase activities of the cyclin and CDK complexes and block transitions of the cell cycle. As a negative regulator of the cell cycle, CDKI P27 kip1 regulates the decision of cell cycle to enter into S-phase or arrested in G1-phase by blocking G1 cyclin dependent kinase activities. Evidence suggests that P27 kip1 may be involved in tumorigenesis and acts as a tumor suppressor gene. In this study, the expression of P27 kip1 in complete hydatidiform mole (CHM), invasive mole (IM) and choriocarcinoma (CC) was investigated as well as in normal chorionic villi by immunohistochemistry. Decreased expression of P27 kip1 was observed in malignant trophoblastic neoplasms with a positive rate of 21.43%, which is less than that in normal chorionic villi (80%) and in CHM (73.33%) (P kip1 in those CHMs with large uterus size for gestational date was lower than that in those with a normal or small uterus for date (42.86% vs 100%). (P kip1 may be involved in the tumorigenesis of gestational trophoblastic neoplasm as a negative regulator of cell cycle, and the expression level of P27 kip1 in trophoblastic cells may be a prognostic factor for CHM.

Murine duodenum does not go through a "solid core" stage in its embryological development.

Embryological development of duodenum is believed to go through a "solid core" stage which subsequently vacuolizes. Failure of vacuolization is thought to be the cause of duodenal atresia. This study examines the embryological development of rat duodenum. Thirty-six time-mated Sprague-Dawley rats were studied. Six fetal duodenal specimens were obtained for each gestational day from day 9 to day 20. These specimens were fixed with formalin, sectioned, stained with haematoxylin and eosin and examined under microscope. The duodenal diameters and the lumen diameters at each gestational date were measured. The foregut started to form at the gestation stage of day 10. The lumen was narrowest on days 12 and 13, but the duodenum did not become a "solid core". No vacuolization was detected through out the development of the duodenum. Embryological development of rat duodenum did not go through a "solid core" stage.