Morphometric study on the characteristic external features of normal and abnormal human embryos

The embryonic period is characterized by organogenesis and accompanying dynamic changes in external features. The measurement of human embryos has been limited to whole body dimensions, such as crown-rump length. More detailed measurements would add quantitative information about these characteristic events and provide a better understanding of normal and abnormal embryonic development. In the present study, we defined axes, landmarks, and measurements for human embryos, and measured 250 externally normal human embryos at Carnegie stages 14-23 (6.5-29.3 mm in crown-rump length, approximately 5-8 weeks of estimated ovulation age) that were fixed in Bouin's solution and preserved in 10% formalin solution. The axes, landmarks, and measurements defined for human embryos are corresponding to those in human and primate fetuses. The whole body, head, face, and extremities were measured using a scale attached to a dissecting microscope. Axial length, head height plus ear-shoulder length plus trunk height, was designated as a new measurement of the whole body, which is comparable with crown-rump length. Approximate standards of these measurements were obtained. The ratios of some measurements to trunk height and between the different parts were also obtained, and several different developmental patterns were recognized. The reproducibility of each measurement was evaluated by measuring 50 specimens three times each at intervals of one or two months. As a pilot study for the application of the proposed measurements, 84 human embryos with external anomalies, including holoprosencephaly, anomalies of extremities, and pharyngeal arch anomalies, were measured using the same method, and a few tendencies characteristic to holoprosencephaly were noticed.     

Analysis of the harmonized growth pattern of fetal organs by multidimensional scaling and hierarchical clustering

The development of an organ may be affected by various growth and differentiation factors released from other organs. These factors are believed to have important effects on the development of multiple organs. To detect and analyze harmonized development among multiple organs, similarities in growth patterns among fetal organs were examined using multivariate analysis. Ninety human fetuses obtained from the Kyoto Collection of Human Embryos were dissected. Harmonized development of organs was evaluated by multidimensional scaling and cluster analysis using measurements (length, width, height, and weight) of the fetal organs. Similar growth patterns were observed between the brain, including cerebrum, diencephalon, and midbrain (cerebrum‐to‐midbrain [Cer‐Mid]), and pituitary (crown‐rump length [CRL] 95–155 mm). Further, similar growth patterns were observed between the liver and Cer‐Mid and cerebellum (Cb; CRL 156–202 mm), and between Cer‐Mid and Cb (CRL 203–253 mm). Similarities in growth patterns were also observed between right and left lungs (CRL 99–235 mm) and between the aorta and heart (CRL 139–187 mm), but not between the lung and pulmonary trunk. These findings revealed synchronized development among fetal organs and suggested a functional and structural relationship among different organs in the prenatal period. These relationships include the existence of common factors in organ development, such as cross‐talk mediated by humoral factors, and the presence of an anatomical and functional relationship in the fetal circulatory system.     

Fetal development of the hand, digits and digit ratio (2D:4D)

OBJECTIVE: The purpose of this study was to investigate growth patterns in human hands, digits and digit ratio (2D:4D) during the fetal period. METHODS: The study is carried out on 161 human fetuses (83 males, 78 females) free from external pathology or malformation with ages ranging between 9 and 40 weeks of gestation. Following general external measurements, length and width of the hand, digit lengths separate for each hand was measured, hand index and the ratio of the lengths of the 2nd finger to the 4th finger (2D:4D index) was computed. RESULTS: Means and standard deviations of the parameters with respect to gestational weeks, months and trimesters were calculated. There was a significant correlation between all parameters and gestational age (p<0.001). No significant differences were observed between sexes or sides for any of the parameters (p>0.05). 2D:4D ratio was significantly higher in females compared to males (p<0.05) and mean 2D:4D did not change with gestational age. CONCLUSION: Detailed information of hand and digit parameters related to the fetal period will reveal the extent of biological variations of hand and digit parameters to be used in future studies. We hope that data acquired in this study will facilitate other studies on hand and digit anomalies, pathologies and variations as well as diagnoses and treatments of such conditions conducted in obstetrics, perinatology, forensic medicine and fetal pathology departments.     

Subclassification of Anencephalic Human Fetuses According to Morphology of the Posterior Cranial Fossa

Anencephaly is a designation for congenital absence of the cranial vault with cerebral hemispheres completely missing or decreased to small masses attached to the base of the skull. The etiology is unknown. Whether the bony tissue or soft brain tissue is a primary factor is also unknown. The present study has focused on the posterior cranial fossa in anencephaly. The goal is to determine whether differences in the posterior cranial fossa could provide a basis for subclassification of anencephalic fetal skeletons. Twenty-three human anencephalic fetuses, at gestational ages 13 to 22 weeks, were studied. Radiologic and cephalometric analyses, including measurements of bone sizes and different angles, were performed. Permission for autopsy of the central nervous system was not available. For comparison of anencephalic findings with normal conditions, standards from a recent publication were used. Foot length served as a parameter for age comparison. The study showed 2 morphologic types of the posterior cranial fossa. One type had a fossa cranial morphology close to normal morphology, whereas the other had a malformed and much smaller posterior cranial fossa. The latter condition was presumed to be due to a primary error in chondral and cranial development. The current skeletal subgrouping might be essential for clinicians’ or pathologists’ future assessment of the autopsy results. The skeletal subgrouping should, if possible, be associated with karyotyping and analysis of the central nervous system. The goal is to distinguish between congenital conditions resulting in anencephaly and acquired conditions resulting in anencephaly. published online November 17, 2004.     

Maternal hypothyroidism and fetal chondro-osseous development in rats.

The bone development of rat fetuses from female Wistar rats thyroidectomized prior to mating was studied, between 16 and 21 days of gestation. The parameters studied in each rat fetus were fetal weight, number of fetuses per litter, radiological data and frequency of appearance of ossification centers, diaphyseal radiological length of long bones, longitudinal ratio between epiphysis and diaphysis of long bones on cleaned and stained limbs, and volumetric tibial studies on the same limbs. Our results show a delay of fetal chondro-osseous development and a delay of weight increase in fetuses from thyroidectomized rats. After onset of fetal thyroid function, the fetal development begins a catch-up growth, which is not sufficient to completely overcome development delay prior to birth.     

Development of the human principal sensory trigeminal nucleus: a morphometric analysis

The anatomical development of the principal sensory trigeminal nucleus was assessed with morphometric features using serial celloidin sections of 15 human brains, including 12 brains obtained from fetuses and neonates. A microscope and an optical electronic planimeter combined with a computer were employed for morphometric measurements of columnar areas, neuronal numbers, neuronal areas and neuronal perimeters to statistically analyze and evaluate the development of neuronal densities, neuropil indexes and circularity ratios. We could not detect the principal sensory trigeminal nucleus in the specimen of 12 gestational weeks (GW). Microscopic observation disclosed that the fetal principal sensory trigeminal neurons approached those of the adult around 33 GW in terms of cell arrangements, amounts of Nissl bodies and morphology of neurons. Our morphometric analysis showed that the columnar volume, the neuronal area and the neuropil index increased with gestational age. The neuronal density decreased with gestational age, especially from 16 to 32 GW. Comparing the neuronal area with the columnar volume, it developed before the columnar volume during the fetal period. The neurons of the principal sensory trigeminal nucleus matured around 33 GW under microscopic observation and in terms of the distribution of neuronal areas. The development of the neuropil may accelerate after individual neurons of principal sensory trigeminal nucleus mature.     

Anatomical development of the fetal uterus

OBJECTIVE: The objective of this study was to gather data on the morphology of the uterus during its development, to provide detailed information regarding the neighboring structures and its variations using anatomical dissections. STUDY DESIGN: Eighty uteri acquired from female fetuses aged 10-40 weeks of gestation were used in this study. Firstly, the relationship between the fetal uterus and the linea terminalis and the position of the uterus within the pelvic cavity was noted. Then the distance between the fundus of the uterus to the promontory and pubic symphysis were measured. Fetal uteri were classified according to their physical appearances. Finally the lengths of the corpus and cervix in three planes and the anteflexion angle were measured. RESULTS: During the fetal period, the fundus of the uterus was above the linea terminalis in 94% and below it in 6% of the cases. The distance between the fundus of the uterus and the promontory significantly correlated with the distance between the fundus of the uterus and the pubic symphysis (p<0.001). This was true for the correlation between the gestational age and the orthogonal lengths of the uterine corpus and cervix (p<0.001). As the gestational age advanced, the anteflexion angle was noted to reduce from 177 degrees to 120 degrees . The shape of the uterus was either cylindrical, pear-shaped, heart-shaped or hourglass-shaped during the fetal period. CONDENSATION: We believe that the data obtained through dissections of the human fetuses in this study will help identifying uterine developmental variations, anomalies and pathologies and will contribute to the studies carried out in obstetrics, perinatology, forensic medicine and fetal pathology departments.     

Abnormalities of the vertebral column and ribs associated with anorectal malformations

Lumbosacral vertebral abnormalities are a common association of anorectal malformations (ARMs) and are one of the determinants of the eventual level of fecal continence that can be achieved. This study used a fetal rat model to investigate the spectrum of axial skeletal maldevelopment that may occur with ARMs. Time-mated pregnant rats received 125 mg/kg of 1% ethylenethiourea (ETU) (experimental group) or vehicle only (control). Their fetuses were examined for external malformations and prepared for staining of their skeletons using Alcian blue and Alizarin red S. ARMs developed in 67/68 (98%) of ETU-exposed fetuses, of which 28 (42%) also developed rachischisis, mainly involving the lumbosacral vertebrae. No skeletal abnormality was found in control fetuses. ETU-exposed fetuses with ARMs and rachischisis had abnormal ossification of the vertebral centrum, abnormal fusion between the neural arches of vertebrae, localized narrow or interrupted thoracic vertebral canal, a widely open vertebral canal in the lumbosacral area (rachischisis), and absence of the lower two sacral and coccygeal vertebrae. Rib abnormalities included absence of two to three floating ribs, abnormal fusion of adjacent proximal segments, and abnormal ramification, irregularity, and angulation of their distal segments. The vertebral and rib abnormalities found in ETU-exposed fetuses with ARMs but no rachischisis were much less severe. In addition to the lumbosacral anomalies that are common with ARMs, severe abnormalities of the thoracic vertebrae and their corresponding ribs may occur also. Fetuses with both ARM and rachischisis tend to have more extensive and severe vertebral and rib anomalies. These observations imply a possible common aetiology for ARMs and vertebral anomalies and are consistent with our understanding of the perceived role of the notochord in axial development.     

Apoptosis in the developing human brain: a preliminary study of the frontal region

BACKGROUND: Natural cell death due to apoptotic mechanisms has been described in various species. Relatively few studies examined this process in humans. AIM: To investigate the distribution of apoptosis in fetal brain tissue. DESIGN: We examined apoptosis in the frontal region of human fetal brain by the TUNEL method in nine fetuses with no neurological conditions, gestational age 14-26 weeks, and three fetuses with structural anomalies of the nervous system (lumbar meningomyeloceles, n=2, hydrocephalus, n=1). RESULTS: In normal fetuses, TUNEL-positive cells were most concentrated in the intermediate zone (IZ) and between 18 and 22 weeks of gestation; cortical apoptosis was not prominent. The fetus with hydrocephalus had increased numbers of TUNEL-positive cells while those with neural tube defects did not differ from normals. CONCLUSION: The definition of normally occurring apoptosis may provide a basis for further studies directed at central nervous system (CNS) malformations.     

Effects of Food Restriction on the Fetal Development during Major Organogenesis in Rats

ABSTRACT This study was designed to determine the effects of food restriction and fasting on fetal development during major organogenesis in Sprague-Dawley rats. The maternal body weight gain markedly decreased during the 60%- and 90%-restricted feeding and fasting periods with a concomitant decrease in the plasma glucose levels. The number of resorptions slightly increased in the 90%-restricted feeding and fasting groups with lower fetal viability. The mean fetal body weight of the restricted feeding and fasting groups and the mean placental weight of male fetuses of the 60%-restricted feeding group were significantly lower than those of the control groups. Ossification of the metacarpi and metatarsi was slightly but significantly retarded by 60%-restricted feeding. The incidence of cardiovascular malformations (mainly ventricular septal defect and abnormal origin of the right subclavian artery) and visceral variations apparently increased in the restricted feeding and fasting groups. Abnormal fetuses tended to be lighter than normal fetuses. In conclusion, maternal food restriction and fasting during major organogenesis caused the fetal growth retardation with slightly delayed ossification and a high incidence of cardiovascular abnormalities in rats. This possibility must be taken into consideration when teratology data with a reduction in maternal food consumption are evaluated.     

Prenatal detection of microtia by MRI in a fetus with trisomy 22

Trisomy 22 is a rare chromosomal abnormality infrequently detected prenatally. External ear abnormalities, in particular microtia, are often associated with trisomy 22, but prenatal detection of microtia has not been reported in association with trisomy 22. We report a fetus with trisomy 22, with fetal MRI findings of microtia, craniofacial dysmorphism, and polygyria. Fetal MRI is a useful tool for auricular assessment and might have utility in the prenatal detection of chromosomal abnormalities, especially among fetuses with structural anomalies.     

Intrapartum surveillance of IUGR fetuses with cardiotocography and fetal pulse oximetry

OBJECTIVE: To investigate the efficacy and safety of intrapartum fetal pulse oximetry, as a predictor of metabolic acidosis at birth of fetuses with intrauterine growth retardation (IUGR). STUDY DESIGN: We studied 18 IUGR fetuses (group I) and a control group of 30 appropriate for gestational age (AGA) fetuses (group II) during labor. Both groups had abnormal fetal heart rate tracings and were monitored simultaneously throughout labor with cardiotocography and fetal pulse oximetry. Apgar scores, pH and base excess of fetal blood obtained from the umbilical artery after delivery were compared in both groups. SETTING: The Fetal Surveillance Unit of the 2nd Department of Obstetrics and Gynecology, Aretaieion Hospital, Medical School, Athens University. RESULTS: In IUGR fetuses, when their oxygen saturation value (FSPO2) was less than 34%, cord artery pH was 7.10 +/- 0.04, base excess -13 +/- -1 mmol/l and Apgar scores < or =5 at the 5th min, and when FSPO2 was over 35%, artery pH was 7.29 +/- 0.08, base excess -8 +/- -2 mmol/l and Apgar scores > or =7 at the 5th minute. In cases of drops of FSPO2)below 30% for more than 2 min, labor was completed operatively and cord pH was 7.00 +/- 0.04, base excess -15 +/- -2 mmol/l and Apgar scores < or =5 at the 5th minute. In AGA fetuses, when FSPO2 was over 30%, artery pH was over 7.20, base excess <-11 mmol/l and Apgar scores > or =9 at the 5th minute; in contrast, when FSPO2 was <30% for 2 min, a cesarean section was performed and cord pH was < or =7.02, base excess > or =-13 mmol/l and Apgar scores < or =4 at the 5th minute. CONCLUSIONS: In IUGR fetuses, FSPO2 values less than 34% represent an acidotic status, while values of > or =35% are well tolerated. Fetal pulse oximetry proved reliable, according to umbilical cord blood measurements and Apgar scores, reducing cesarean deliveries in cases of nonreassuring cardiotocographic patterns in IUGR fetuses.     

Developmental Toxicity of Aspirin Prenatally Given to Rats: Assessment in Sic: Wistar-KY Rats

Abstract Slc:Wistar-KY rats were administered orally with 62.5, 125, 187.5 or 250 mg/kg aspirin suspended with 0.5 % CMC-Na on days 9–11 of gestation (plug += day 0). Suppression of maternal weight gain and food consumption during treatment was observed at and over 187.5 mg/kg. At term, the fetal mortality increased at and over 187.5 mg/kg and the fetal weight was lowered at and over 125 mg/kg. Among 15 live fetuses at 250 mg/kg, 4 had external malformations. In the skeletal examination (double staining), skeletal anomalies increased at and over 187.5 mg/kg. The skeletal variations such as vertebral anomalies, fused costal cartilages and increased presacral vertebrae were often encountered and delayed ossification was also found at and over 125 mg/kg. The internal anomalies tended to increase at and over 187.5 mg/kg. The live birth rate was significantly lower at 187.5 mg/kg than that in controls, and all pups, except for 3 from a dam, died before weaning. At 125 mg/kg, the pivoting locomotion on day 7 post partum was poorer as compared with controls. The physical and functional development at 62.5 mg/kg was not changed. There were no significant effects on male offspring in the open-field, rotarod, under-water T-maze and avoidance learning tests. However, in the Biel T-maze test (9–10 weeks of age), the aspirin-treated groups showed more errors and the increased elapsed time on the 1st trial day than controls. These results indicate that aspirin may induce a slight learning defect on rat offspring even at the non-teratogenic dose and the Biel T-maze test is more sensitive than any other learning tests given in this study.     

Developmental Toxicity of Aspirin Prenatally Given to Rats: Assessment in Slc: Wistar-KY Rats

ABSTRACT  Slc:Wistar-KY rats were administered orally with 62.5, 125, 187.5 or 250mg/kg aspirin suspended with 0.5 % CMC-Na on days 9–11 of gestation (plug += day 0). Suppression of maternal weight gain and food consumption during treatment was observed at and over 187.5 mg/kg. At term, the fetal mortality increased at and over 187.5 mg/kg and the fetal weight was lowered at and over 125 mg/kg. Among 15 live fetuses at 250 mg/kg, 4 had external malformations. In the skeletal examination (double staining), skeletal anomalies increased at and over 187.5 mg/kg. The skeletal variations such as vertebral anomalies, fused costal cartilages and increased presacral vertebrae were often encountered and delayed ossification was also found at and over 125 mg/kg. The internal anomalies tended to increase at and over 187.5 mg/kg. The live birth rate was significantly lower at 187.5 mg/kg than that in controls, and all pups, except for 3 from a dam, died before weaning. At 125 mg/kg, the pivoting locomotion on day 7 post partum was poorer as compared with controls. The physical and functional development at 62.5 mg/kg was not changed. There were no significant effects on male offspring in the open-field, rotarod, under-water T-maze and avoidance learning tests. However, in the Biel T-maze test (9–10 weeks of age), the aspirin-treated groups showed more errors and the increased elapsed time on the 1st trial day than controls. These results indicate that aspirin may induce a slight learning defect on rat offspring even at the non-teratogenic dose and the Biel T-maze test is more sensitive than any other learning tests given in this study.     

Developmental Toxicity of Aspirin Prenatally Given to Rats: Assessment in Sic: Wistar-KY Rats

Abstract Slc:Wistar-KY rats were administered orally with 62.5, 125, 187.5 or 250 mg/kg aspirin suspended with 0.5 % CMC-Na on days 9–11 of gestation (plug += day 0). Suppression of maternal weight gain and food consumption during treatment was observed at and over 187.5 mg/kg. At term, the fetal mortality increased at and over 187.5 mg/kg and the fetal weight was lowered at and over 125 mg/kg. Among 15 live fetuses at 250 mg/kg, 4 had external malformations. In the skeletal examination (double staining), skeletal anomalies increased at and over 187.5 mg/kg. The skeletal variations such as vertebral anomalies, fused costal cartilages and increased presacral vertebrae were often encountered and delayed ossification was also found at and over 125 mg/kg. The internal anomalies tended to increase at and over 187.5 mg/kg. The live birth rate was significantly lower at 187.5 mg/kg than that in controls, and all pups, except for 3 from a dam, died before weaning. At 125 mg/kg, the pivoting locomotion on day 7 post partum was poorer as compared with controls. The physical and functional development at 62.5 mg/kg was not changed. There were no significant effects on male offspring in the open-field, rotarod, under-water T-maze and avoidance learning tests. However, in the Biel T-maze test (9–10 weeks of age), the aspirin-treated groups showed more errors and the increased elapsed time on the 1st trial day than controls. These results indicate that aspirin may induce a slight learning defect on rat offspring even at the non-teratogenic dose and the Biel T-maze test is more sensitive than any other learning tests given in this study.     

Visceral anomalies in prenatally adriamycin-exposed rat fetuses: a model for the VATER association

Adriamycin is teratogenic if given to pregnant rats. A wide range of anomalies involving the gastrointestinal, renal, and cardiovascular systems has been described, similar to the VATER association, yet it is not known if they are identical to the human pattern. The aim of this study was to document the visceral anomalies in rat fetuses exposed to adriamycin and to determine their similarities with the congenital defects in humans with the VATER association. The results revealed a spectrum of very similar anomalies. Furthermore, the characteristics of the tracheo-oesophageal anomalies had a lot of features in common with the human pattern. We conclude that the adriamycin-treated fetal rat is an excellent model for studying the VATER association.     

The development of jejunum and ileum during the fetal period

OBJECTIVE: In our study, the morphologic structures of the jejunum and ileum sections of small intestine were investigated in human fetuses during the fetal period. MATERIALS AND METHODS: The study was realised on 131 human fetuses (male: 69; female: 62) with ages between 10 and 40 weeks, which have got no external pathology and anomalies. The external sizes of fetuses were measured, and then the structures in the abdominal cavity were determined by the abdominal dissection. The localization of jejunum and ileum, duodenojejunal flexure and ileal orifice points, the measurements of macroscopic diameters, types of the mass of jejunum and ileum and the localization according to the abdominal regions of the mass of jejunum and ileum were determined. Also, the samples of the jejunum and ileum were examined both macroscopically and microscopically. The thickness of tunica serosa, tunica muscularis and tunica mucosa was determined under the light microscope. RESULTS: According to the sexes, gestational ages and groups, the averages and the standard deviations of the all parameters were determined. The correlations between the parameters were determined. The percentage of parameters was compared according to sex and among groups. No differences were found in parameters between sexes (p<0.05). The macroscopic parameters were increased according to the gestational age. The thickness of tunica serosa did not change according to the gestational age. CONCLUSION: It is thought that the data we have will help the evaluation of jejunum and ileum in intrauterine period; we also believe that the data in our study may help in the diagnosis and treatment of anomalies and pathologies in fetal period that belongs to jejunum and ileum.     

Skeletal and total body volumes of human fetuses: assessment of reference data by spiral CT

OBJECTIVE: To define reference data for skeletal and total body volumes of normal human fetuses. MATERIALS AND METHODS: Spiral CT was used to assess the skeletal and total body volumes of 31 normal human stillborn infants with gestational age (GA) and body weight (BW) ranging from 14 to 41.5 weeks and 22 to 3,760 g, respectively. CT scans (slice thickness 2.7 mm, pitch 0.7) were performed within the first 24 h after delivery. Precise bone and soft-tissue windows were defined from analysis of the density along the diaphysis of the fetal long bones and from the measurement of a phantom that mimics soft tissues. Lengths and volumes were obtained from 3D reconstructions. The femur lengths measured from CT images (FLct) were compared with those provided by US studies (FLus). RESULTS: Significant correlations ( r>0.9) were found between BW, measured volumes of the entire skeleton or head, long-bone lengths, biparietal diameter and GA. Strong linear correlations ( r>0.98) were observed between FLct and FLus. CONCLUSIONS: Skeletal and total body volume values obtained using spiral CT were significantly correlated with fetal biometric measurements. These data could complement those obtained in obstetric investigations with US.