ABSTRACT Two unbiased stereological techniques, the disector and the fractionator have been introduced. Synapse-to-neuron ratios were calculated from estimates of the numerical densities of neurons and synapses in the rat cerebral cortex. These estimates were made using the disector method at the light and electron micro- scopical levels. Neuronal nuclei were as the counting unit for neurons and paramembranous densities for synapses. The fractionator method was employed to estimate the total number of cerebellar Purkinje cells in rats. We employed a five-stage scheme to count the nucleoli of Purkinje cells. The cerebellum was first divided into uniform random slices, which were cut, in turn, into strips. The chosen strips were cut into pieces. A systematic selection of tissues was taken, and embedded together in the same mold. Subsequently the sections sampled were examined with a light microscope. All Purkinje cell nucleoli visible in these sections were counted.
ABSTRACT Reproductive and developmental toxicity of triphenyltin chloride (TPTCI) was evaluated in rats. Although no significant increase in the incidence of fetuses with malformations was observed following ad- ministration of TPTCl during organogenesis, a significant increase in the incidence of postimplantation embryonic loss was found. TPTCl during early pregnancy, especially on days 0-3 of pregnancy, caused implantation failure, i. e., preimplantation embryonic loss. The effects of TPTCl on the uterine function, as a cause of implantation failure, were determined using pseudopregnant rats. TPTCl was given on days 0-3 of pseudopregnancy and the decidual cell response was induced on day 4 of pseudopregnancy. Rats was sacrificed on day 9 of pseudopregnancy and the uterine weight served as an index of the uterine decidualization. A significantly lower weight of the uterus, which indicates the suppression of uterine decidualization, was found at the doses which induced implantation failure. These doses of TPTCl also caused a significant de- crease in the progesterone levels, which indicates reduced ovarian function. These findings suggest that TPTCl ex- erts adverse effects on uterine decidualization correlated with the reduction in serum progesterone levels and these effects are responsible, at least in part, for the implanta- tion failure induced by TPTCI.
ABSTRACT The roles of nestin in neural tube development were studied using immunostaining and antisense experiments in rat embryos. Nestin was detected in the neural tube of embryos of day 10.5 of gestation (ElOS), while no nestin staining was observed in E9.5 embryos in which the neural plate comprised 3 to 4 layers of neuroepithelii cells. As embryos developed, the neural tube became comprised of multiple cell layers and staining was observed in filamentous structures spanning from the ventricular surface to the pial surface of the neural tube. Nestin accumulation was suppressed in the neural tube of embryos treated with nestin antisense oligodeoxynucleotide (ODN). The treated embryos showed two types of neural tube deformation. One type was a thin neural tube which had 3 to 4 layers of neuroepithelial cells and the other was a local distribution of neuroepithelial cells near the basement membrane. While neuroepithelial cells in the neural tube were fewer in embryos treated with nestin antisense ODN than in controls, the percentage of Islet-l-positive neurons relative to the neuroepithelial cells was not different between the treated and control embryos. These results suggested that nestin plays roles in the proliferation of neural tube cells and in the formation and the maintenance of multiple cell layers in the neural tube but not in suppression of development of Islet-l-positive neurons.
ABSTRACT To investigate the incorporation of oligonucleotides (ODNs) into the tissues of cultured fetal mouse palates and their effects on in vitro palatogenesis, we cultured day-12.5 fetal mouse palates in a chemically defined serumless medium supplemented with either antisense or sense ODNs to epidermal growth factor receptor (EGF-r). The EGF-r ODNs were found to be incorporated into the palatal tissue and remained detectable for at least 72 hr. Immunohistochemical and immunoblot analyses revealed that the treatment with 5pM EGF-r antisense ODN suppressed the production of EGF-r protein. No pathological change was observed in the explanted palates when they were treated with 5 pM EGF-r antisense or sense ODNs, but the treatment with 10 or 20 pM ODN caused pyknotic changes in the palatal epithelium, probably due to the ODN toxicity. The present results indicate that under optimal conditions, antisense ODNs to EGF-r can be incorporated into fetal organs cultured in vitro and specifically inhibit the production of EGF-r protein. Since the suppression of the production of EGF-r protein did not prevent the palate fusion, EGF and/or EGF-r alone may not play a critical role in palatogenesis, as suggested by previous studies. The antisense ODN technique could be of potential use for analyzing the roles of specific molecules in normal and abnormal morphogenesis.
ABSTRACT In spite of the description of more than 70 cases of Seckel syndrome (SS) or Seckel-like primordial microcephalic dwarfism, reports about investigations into the central nervous system pathology in SS remaind infrequent Here we comment on the thorough neuropathological examination of the brain in a familial case of Seckel-like microcephalic dwarfism. The male fetus of a 6 gravida, 3 para was aborted at 19 weeks of gestation after prenatal ultrasound examination with the demonstration of severe microcephaly and retarded intrauterine development The propositus had two healthy sisters. Of two aborted fetuses and one deceased sibling, the deceased had also exhibited a Seckel-like phenotype as well as, in MRI scans, micrencephaly, callosal agenesis and pachygyria. Neuropathological examination of the brain in the propositus resulted in the demonstration of two main categories of changes: (1) defective telencephalic midline structures (arhinencephaly as well as callosal, septal, fornical, and hippocampal agenesis), and (2) impairment of migration (micrencephaly with lack of cortical neuroblasts in both the telencephalon and the rhombencephalon as well as heterotopias in the former). These findings corresponded with those described in the few neuropathological and neuroradiological literature reports, indicating that there appears to be in SS-like primordial microcephalic dwarfism and a characteristic, although not specific brain pathology which might be adequately summarized by the designation mediodysgenetic micrencephaly. The genetic background of SS as a basis for the CNS maldevelopment is discussed.
ABSTRACT We report an autopsy case of acrania with a review of the literature. A 31-year-old woman was admitted in poor genaral condition and diagnosed as pregnant at the 26th week of gestation. The fetus was suspected to be anencephalic or hydrocephalic by ultrasonography. She delivered a stillbirth male baby at the 28th week of gestation. Autopsy showed the cranium lacked the cranial vault The scalp directly covered the hydrocephalic brain without calvaria. No cerebellum was found macroscopically. On histological examination, the thinned cerebral layer was composed of white matter-like brain tissue with glial and ependymal cells. In the cerebral layer near the base of the skull, a few NSE-positive neurons among many GFAP-positive glial cells and oligodendrocyte-like cells were observed. The choroid plexuses were observed inside the ependymal layers. The brain stem and the spinal cord were normally preserved with clusters of NSE-positive neurons. Agnethia and horseshoe kidney were combined as malformations other than the brain. We reviewed 42 cases of acrania from the literature.