ABSTRACT Previous studies suggest that jaw movement is an important factor in the development of cartilage in the temporomandibular joint during the prenatal and postnatal periods. In the present study, the effects of fetal jaw movement on the articular disk were studied in mice by restraining the opening movement of the mouth using the mouse exo utero development system. At embryonic day 18.5, the articular disk was reduced in size in the embryos whose maxilla and mandible were sutured (sutured group) and there were changes in the cellular morphology of the mesenchymal cells in the disk. The volume of the articular disk, the total number of cells and the number of 5-bromo-2′-deoxyuridine-positive cells in the articular disk were significantly lower in the sutured group than in the non-sutured control group. Our data revealed that fetal jaw movement affects the development of the articular disk in the temporomandibular joint.
ABSTRACT The aim of the investigation was to describe the chromosomal deletions identified by a birth defects registry with respect to the chromosomes involved, pregnancy outcome, method of diagnosis, inheritance, sex, and the diagnosis of major structural birth defects. Cases were derived from a population-based birth defects registry in Hawaii and comprised all infants and fetuses with chromosomal deletions delivered during 1986–2003. A total of 71 cases were identified through a statewide birth defects registry in Hawaii during 1986–2003. The chromosomes involved in the greatest proportion of deletions were chromosomes 22 (14.1%), 4 (11.3%), and 5 (11.3%). Live births accounted for 58 (81.7%) of the cases. Diagnosis was made by amniocentesis or chorionic villus sampling in 19 (26.8%) of the cases. Of the 18 cases with known inheritance, the deletion was inherited in 5 (27.8%) and de novo in 13 (72.2%). Males accounted for 28 (39.4%) and females for 43 (60.6%) of the cases. Major structural birth defects were identified in 51 (71.8%) of the cases. Chromosomal deletions do not appear to affect all chromosomes equally. Most of the chromosomal deletions that were detected occurred among live births and were de novo conditions. Infants and fetuses with chromosomal deletions are more likely to be females and to be associated with major structural birth defects.
ABSTRACT Morphometric and histological studies of the pons were performed by light microscopy in 28 cases of externally normal human fetuses ranging from 90 to 246 mm in crown-rump length (CRL) and from 13 to 28 weeks of gestation. The brainstems of fetuses were embedded in celloidin or paraffin, and transverse sections were prepared. The pons was divided into two regions at the most ventral margin of the medial lemniscus at the level of the motor trigeminal nucleus. The relationships between the total dorsoventral length, ventral length, and dorsal length of the pons versus CRL and gestational ages were calculated, and empiric formulas were fitted. It was found that the ventral portion increased in size more rapidly than the dorsal portion. The proportion of the ventral portion in the total dorsoventral length was constitutively higher than that of the dorsal portion in the present range of CRL. In the pontine nuclei, from 235 mm in the CRL, some large cells with rich cytoplasm, pale nuclei, and a distinct nucleolus appeared on the dorsal side of the pyramidal tract. According to Weigert stained preparations, the first myelinated fibers in each motor root of the trigeminal, abducent, and facial nerves were recognized at 130–140 mm in CRL and the medial lemniscus at 230–235 mm.
ABSTRACT A 32-year-old gravida 2, para 1 woman, with a previous uneventful pregnancy, underwent first trimester ultrasound screening for Down syndrome at 13 weeks according to the Fetal Medicine Foundation guidelines (http://www.fetalmedicine.com/pdf/11-14/english/FMF-English.pdf). The ultrasound showed increased nuchal translucency (NT) of 8.9 mm with an estimated risk of Down syndrome of 1:8. Fetal karyotype was normal 46,XX by chorionic villus sampling. The patient underwent weekly ultrasound and at 19 weeks of gestation, a dilatation of the 4th ventricle with partial agenesis of the cerebellar vermis and normal posterior fossa were observed by transvaginal transcerebellar section of the fetal head. This finding was consistent with a diagnosis of Dandy-Walker variant and the patient opted for termination of pregnancy after extensive counselling. Autoptic examination confirmed the prenatal ultrasonographic findings and revealed signs of an underlying cerebro–fronto–facial syndrome due to the presence of facial dysmorphisms consistent with horizontal eyelid, high nasal root, low set ears and a wide forehead. Increased NT is not only a common phenotypic expression of chromosomal abnormalities, but is also associated with a wide range of fetal defects and genetic syndromes. Careful ultrasonographic follow-up is mandatory in all cases of increased first trimester nuchal translucency with normal karyotype in order to identify associated anomalies.
ABSTRACT The case of a 36 year-old primigravida is presented. After a normal anomaly scan at 22 weeks and a normal pregnancy, she went into labor at term. Dystocia due to massive abdominal distension complicated the second stage. The newborn girl had meconium peritonitis with colonic perforation and required colonic resection with colostomy. Genetic testing detected cystic fibrosis. In this case complex meconium peritonitis developed silently (without any clinical sign) after a normal anomaly scan. This has not been reported since the start of the widespread use of obstetric ultrasound. Late meconium peritonitis can escape detection and should be thought of in cases of unexpected abdominal distension causing dystocia.
ABSTRACT In October 2006, a new revision of the draft guideline (OECD Guideline for the Testing of Chemicals, Proposal for a New Guideline 426. Developmental Neurotoxicity Study) and Draft Document of the Retrospective Performance Assessment (RPA) of the Draft Test Guideline 426 on Developmental Neurotoxicity were distributed following incorporation of the results of the Expert Consultation Meeting in Tokyo on May 24–26, 2005. The draft guideline consists of 50 paragraphs and an appendix with 102 references; and the draft RPA consists of 37 paragraphs with 109 references. National coordinators were requested to arrange for national expert reviews of these draft documents in their member countries. Members of the Developmental Neurotoxicology (DNT) Committee of the Japanese Teratology Society (JTS) reviewed, discussed, and commented on the draft Test Guideline Proposal. The DNT Committee of the JTS also commented on the draft document of the RPA. These comments were sent to the OECD Secretariat. The DNT Committee of the JTS expects the comments to be useful for the finalization of these draft documents.