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PubMed2002

Oligodendrocyte and astrocyte development in rodents: an in situ and immunohistological analysis during embryonic development.

Lineally related multipotent neuroepithelial cells (NEP), neuronal restricted precursors (NRP), and glial restricted precursors (GRP) have been identified in the spinal cord. To determine the sequence of differentiation and identify lineage and stage-specific markers, we have examined the spatiotemporal expression of established glial markers during rodent embryonic development and within fetal cell culture. In this report, we show that proliferating stem cells in the developing neural tube do not express any glial markers at E10.5. By E11, however, glial precursors have begun to differentiate and at least two regions of the ventral neural tube containing glial precursor cells can be distinguished, an Nkx2.2/Neurogenin 3 (Ngn3) domain and a platelet-derived growth factor receptor alpha (PDGFRalpha)/Olig2/Sox10 domain. Radial glia, as identified by RC1 immunoreactivity, develop in concert with other glial precursors and can be distinguished by their morphology, spatial distribution, and antigen expression. Astrocytes as assessed by glial fibrillary acidic protein (GFAP) immunoreactivity are first detected at E16. A novel dorsal domain of CD44 immunoreactivity that can be distinguished from the more ventral glial precursor domains can be detected as early as E13.5.

Animals↗

PubMed1978

Development of the compound eyes of dragonflies (Odonata). II. Development of the larval compound eyes.

The development of the compound eye was analyzed by marking individual ommatidia and by studying naturally occurring pigment band patterns. New ommatidia are added to the eye along its anterior margin. This changes the directions of view of the older ommatidia with the greatest change occurring in the fovea. New ommatidia are added to the fovea medially, and old ones are removed laterally as their interommatidial angles and directions of view in the visual field change. Over one-third of the aeshnid ommatidia are foveal during at least one of the early larval instars, and are then used for peripheral vision later in development. The design of each ommatidium is a compromise so that it is adapted for all stages of development, but sometimes better adapted for one instar than for others. Factors which are balanced for best vision are lens diameter, facet admission function, interommatidial angle, and inclination of the optic axis to the eye surface. Ommatidia are described in terms of these factors throughout their life history, from initial differentiation anteriorly, through passage through the fovea, to their final relatively posterior location.

Animals↗

PubMed1988

Skull development during anuran metamorphosis: I. Early development of the first three bones to form--the exoccipital, the parasphenoid, and the frontoparietal.

In anuran amphibians, cranial bones typically first form at metamorphosis when they rapidly invest or replace the cartilaginous larval skull. We describe early development of the first three bones to form in the Oriental fire-bellied toad, Bombina orientalis--the parasphenoid, the frontoparietal, and the exoccipital--based on examination of serial sections. Each of these bones is fully differentiated by Gosner stage 31 (hindlimb in paddle stage) during premetamorphosis. This is at least six Gosner developmental stages before they are first visible in whole-mount preparations at the beginning of prometamorphosis. Thus, developmental events that precede and mediate the initial differentiation of these cranial osteogenic sites occur very early in metamorphosis--a period generally considered to lack significant morphological change. Subsequent development of these centers at later stages primarily reflects cell proliferation and calcified matrix deposition, possibly in response to increased circulating levels of thyroid hormone which are characteristic of later metamorphic stages. Interspecific differences in the timing of cranial ossification may reflect one or both of these phases of bone development. These results may qualify the use of whole-mount preparations for inferring the sequence and absolute timing of cranial ossification in amphibians.

Animals↗

PubMed2001

LF-interpretability and language development: a study of verbal and nominal features in Greek normally developing and SLI children.

This paper includes (i) a comparison of the developmental pattern of certain morphosyntactic features in normally developing (ND) Greek children with similar data from a group of children with specific language impairment and (ii) a new analysis of the differences found. The analysis is based on a minimalist notion of LF interpretability. Depending on the feature-specification of lexical items (i.e., [+/- interpretable] at LF), a different route of development follows. In addition, phonological salience of both interpretable and noninterpretable features is argued to play an important role in an account of crosslinguistic differences in both normal and exceptional development.

Child↗

PubMed1997

Postembryonic development of the olfactory system in the moth Manduca sexta: primary-afferent control of glomerular development.

The olfactory system of the sphinx moth Manduca sexta bears many similarities to its vertebrate counterpart in functional organization, physiology and development. In the moth, the antenna (the olfactory organ) and the antennal lobe (the primary olfactory center) of the brain arise during postembryonic metamorphic development and are accessible, independently manipulable, and structurally relatively simple. In addition, they house a conspicuous, sexually dimorphic subsystem specialized for detection of a specific pheromonal odor. These features make this system experimentally favorable for studies of development of olfactory glomeruli. Such studies have demonstrated the importance of regulatory interactions among sensory axons, glial cells and antennal-lobe neurons.

Journal Article↗

PubMed1989

Development of spare human preimplantation embryos in vitro: an analysis of the correlations among gross morphology, cleavage rates, and development to the blastocyst.

Following in vitro fertilization, the criteria commonly used to select human embryos for transfer are the cleavage rate and gross morphology, the contention being that those embryos which divide more rapidly and have regular, spherical blastomeres are more likely to lead to a pregnancy. In order to assess the validity of this assumption, the development in vitro of spare embryos was investigated. Eggs and embryos were cultured in Earle's balanced salt solution containing 10% heat-inactivated patient's serum, and insemination was performed at 40 hr post human chorionic gonadotropin (hCG). At 82-90 hr post hCG, up to four embryos were transferred. Any spare embryos were cultured in the same medium for up to 6 days and scored daily for cell number and morphology using a "quality" scale of 4-1 according to degree of fragmentation and shape of the blastomeres. Of 317 fertilized eggs, 55 (17%) developed to the fully expanded blastocyst stage. The remaining embryos ceased development at the one-cell (6; 2%), two-cell (49; 15%), four-cell (110; 35%), eight-cell (61; 19%), and cavitating morula (36; 11%) stages. The relationship between developmental arrest and gross morphology is discussed.

Blastocyst↗

PubMed1996

Abnormal gonadal differentiation in two subjects with ambiguous genitalia, Mullerian structures, and normally developed testes: evidence for a defect in gonadal ridge development.

Among a group of patients with abnormal sexual differentiation, we have identified two subjects who had a 46,XY karyotype, ambiguous genitalia, and well-developed Müllerian structures, but normal appearing testes. The presence of ambiguous genitalia and persistent Müllerian structures implied both Leydig cell and Sertoli cell dysfunction, hence, gonadal dysgenesis. However, the normal testicular histology suggested that the underlying abnormality was not a defect in testis determination itself but an abnormality in timing of gonadal ridge and testis development. In one of the two subjects genomic DNA was available. The sequence of the SRY gene was normal. Because rare patients with partial androgen insensitivity may have a similar phenotype, the AR gene was evaluated by denaturing gradient gel electrophoresis (DGGE) and was normal. Some subjects with mutation of the WT1 gene or with deletion of the distal short arm of chromosome 9 may have similar phenotypes. The WT1 gene was studied by single-strand conformation polymorphism (SSCP) analysis and was normal. In addition, there was no loss of heterozygosity of polymorphic markers in distal 9p. The gene for Müllerian inhibiting substance (MIS) was also studied by SSCP and was normal. Although the exact mechanism for the defect in the two subjects is unknown, it may be due to an abnormality in a gene or genes involved in the timing of gonadal ridge development.

Cell Differentiation↗

PubMed2002

Integrated Child Development Services (ICDS) scheme: a program for holistic development of children in India.

The Integrated Child Development Services (ICDS) scheme is the largest program for promotion of maternal and child health and nutrition not only in India but in the whole world. The scheme was launched in 1975 in pursuance of the National Policy for Children. The scheme has expanded in the last twenty-seven years form 33 projects to 5171 blocks. ICDS is a multi-sectoral program and involves several government departments. The program services are coordinated at the village, block, district, state and central government levels. The primary responsibility for the implementation of the program lies with the Department of Women & Child Development at the Centre and nodal department at the states, which may be Social Welfare, Rural Development, Tribal Welfare or Health Department or an independent Department. The beneficiaries are children below 6 years, pregnant and lactating women and women in the age group of 15 to 44 yrs. The beneficiaries of ICDS are to a large extent identical with those under the Maternal and Child Health Program. The program provides an integrated approach for converging all the basic services for improved childcare, early stimulation and learning, health and nutrition, water and environmental sanitation aimed at the young children, expectant and lactating mothers, other women and adolescent girls in a community. ICDS program is the reflection of the Government of India to effectively improve the nutrition and health status of underprivileged section of the population through direct intervention mechanism. The program covers 27.6 million beneficiaries with supplementary nutrition. The program services and beneficiaries has essentially remained the same since 1975. Recently a review of the scheme was held, sponsored by Government of India, which suggested modifications in the health and nutrition component of ICDS scheme to improve the program implementation and efficiency.

Adolescent↗

PubMed2003

Results of transplanting developing third molars as part of orthodontics space management. Part 2: results following the orthodontic treatment of transplanted developing third molars in cases of aplasia and premature loss of teeth with atrophy of the alveolar process.

MATERIAL AND METHODS: The aim of this study was to assess the effects of atrophy of the alveolar process and subsequent orthodontic treatment on the transplantation results of developing third molars. The material consisted of 35 teeth transplanted to an atrophied alveolar process. 19 of these teeth were treated orthodontically subsequent to transplantation. The control group consisted of 61 developing molars transplanted to a new extraction socket. The transplanted teeth were followed up clinically and radiographically for a mean period of 3.2 years. RESULTS: The success rate was 85% for transplants to new extraction sockets and 84% for transplants to atrophied jaw sections with subsequent orthodontic treatment. In contrast, transplants to atrophied jaw sections without subsequent orthodontic treatment showed a significantly (p < or = 0.001) lower success rate of only 37.5%. These poorer results were due to persistent infraocclusion and ankylosis. CONCLUSIONS: Even in cases with atrophy of the alveolar process, a transplantation with subsequent orthodontic treatment represents a promising treatment concept, whereas teeth without subsequent orthodontic treatment showed a lower success rate. Orthodontic tooth movement had no negative effect on the healing rates of transplanted developing third molars.

Adolescent↗

PubMed2005

Mutation in the Arabidopisis thaliana DEK1 calpain gene perturbs endosperm and embryo development while over-expression affects organ development globally.

A T-DNA insertion in the Arabidopsis thaliana DEK1 gene, encoding a calpain-like cysteine proteinase with a predicted membrane anchor, causes unorganized embryo development displaying irregular mitotic divisions in the embryo proper and suspensor. Embryo development is arrested at the globular stage, and the embryo proper lacks a defined protoderm. In the endosperm, the aleurone-like peripheral cell layer is partly or completely lacking. The Arabidopsis DEK1 wild-type transcript is expressed evenly throughout the endosperm and the embryo in developing seed as determined using in situ hybridization. The conclusion that the observed phenotype is caused by a T-DNA insertion in the Arabidopsis DEK1 gene is confirmed by complementation with the Arabidopisis DEK1 genomic sequence, as well as analysis of a second T-DNA insertion allele. Over-expression of the Arabidopsis DEK1 gene coding sequence under the control of the 35S promoter causes a number of developmental phenotypes, including a global lack of trichomes, leaves exhibiting improper dorsiventral symmetry and aberrant cell organization in flowers. We interpret the data to suggest a role for DEK1 in providing cells with positional clues for an appropriate developmental context within plant tissues.

Alleles↗

PubMed2006

Role of sugars in regulating transfer cell development in cotyledons of developing Vicia faba seeds.

Transfer cell formation in cotyledons of developing faba bean (Vicia faba L.) seeds coincides with an abrupt change in seed apoplasm composition from one dominated by hexoses to one in which sucrose is the principal sugar. On the basis of these observations, we tested the hypothesis that sugars induce and/or sustain transfer cell development. To avoid confounding effects of in planta developmental programs, we exploited the finding that adaxial epidermal cells of cotyledons, which do not become transfer cells in planta, can be induced to form functional transfer cells when cotyledons are cultured on an agar medium. Growth rates of cotyledons cultured on hexose or sucrose media were used to inform choice of sugar concentrations. The same proportion of adaxial epidermal cells of excised cotyledons were induced to form wall ingrowths independent of sugar species and concentration supplied. In all cases, induction of wall ingrowths coincided with a marked increase in the intracellular sucrose-to-hexose ratio. In contrast, further progression of wall ingrowth deposition was correlated positively with intracellular sucrose concentrations that varied depending upon external sugar species and supply. Sucrose symporter induction and subsequent maintenance behaved identically to wall ingrowth formation in response to an external supply of hexoses or sucrose. However, in contrast to wall ingrowth formation, induction of sucrose symporter activity was delayed. We discuss the possibility of intracellular sugars functioning both as signals and substrates that induce and control subsequent development of transfer cells.

Carbohydrates↗

PubMed1982

Maternal methadone administration: deficit in development of alpha-noradrenergic responses in developing rat brain as assessed by norepinephrine stimulation of 33Pi incorporation into phospholipids in vivo.

The effects of perinatal methadone exposure on the development of noradrenergic responses in the brain were examined by assessing the ability of intracisternally administered norepinephrine to stimulate 33Pi incorporation into phospholipids in vivo; the effect of norepinephrine is mediated by alpha1-receptors juxtaposed to noradrenergic nerve terminals. Although there was no difference in basal (unstimulated) incorporation of 33Pi, a deficit in norepinephrine-induced stimulation of incorporation was found throughout the preweaning period in offspring of dams treated daily with methadone beginning in midgestation. This effect was not seen when methadone was given during the postnatal period. Since perinatal methadone exposure also delays development of presynaptic catecholaminergic nerve terminals in the brain, these results support the view that perinatal exposure to methadone depresses overall central noradrenergic synaptic function; however, the effects on presynaptic development and on receptor-mediated responses appear to be separable in that they display differences in the critical age periods of sensitivity to perturbation by the drug.

Animals↗

PubMed1994

Closely spaced recurrent hippocampal seizures elicit two types of heightened epileptogenesis: a rapidly developing, transient kindling and a slowly developing, enduring kindling.

Kindling is widely accepted as a model of chronic epilepsy as well as a model of plasticity in the nervous system. Conventional kindling studies have used infrequent stimuli (separated by many hours) to establish a fully kindled state in which enhanced responses (kindled motor seizures and protracted afterdischarges) are consistently triggered by stimuli that initially did not elicit such responses. The enhanced responses occur even after a prolonged stimulus-free interval. Whereas the establishment of a kindled state with traditional stimulus protocols takes several weeks, our previous work showed that kindling could take place much more quickly when the interstimulus interval was set at 30 min (rapid kindling). In this report we tested whether rapid kindling protocols share with traditional kindling protocols the ability to establish a fully kindled state. Using different stimulus protocols involving recurrent hippocampal seizures, we characterized two types of kindling. 'Rapid kindling' developed over hours, but was transient, with a decay rate of a few days so that a fully kindled state did not persist. In contrast, 'slow kindling' developed over several weeks and was enduring, apparently permanent, being associated with a fully kindled state. These findings suggest that, while having certain similarities, the two types of kindling arise from dissimilar mechanisms. The existence of these two types of kindling has implications for epileptogenesis in humans. Moreover, the protocols developed in this work provide a useful means to control for the effects of seizures that are not related to mechanisms underlying a fully kindled state.

Animals↗

PubMed1989

Early development in mice: V. Sensorimotor development of four coisogenic mutant strains.

Effects on sensorimotor development of four genes (at, Re, fz, and Wv) involved in coat color differences were investigated by employing four coisogenic strains of mice with the same genetic background C57BL/6JOrl (B6). Compared to wild-type B6, two mutations (fz and Wv) showed pleiotropic effects on development but the direction of these effects (delay or advance) differed in different tests. Body weight was decreased for each mutation. Heterozygosity vs. homozygosity at the W locus caused differences in crossed extensor, bar holding and female body weight. Epistatic effects between the at and Re genes were investigated by developing a double coisogenic strain, and were found for righting, hindpaw grasping, vibrissae placing responses and weight.

Animals↗

PubMed1990

Comparison of six-day bovine embryo development in uterine tube (oviduct) epithelial cell co-culture versus in vivo development in the cow.

A study was designed to evaluate and compare the appearance of embryos recovered from donor cows on Day 6 to embryos from in vivo fertilized cow zygotes developed to Day 6 on uterine tube (oviduct) epithelial cell co-culture using serum-free CZB medium. Embryo stage of development and quality score were assessed. Hoechst 33342 DNA stain was then used to determine the total number of blastomeres, the number of poor nuclei and the number of nuclei in mitosis. Mean cell counts did not differ for the 70 embryos evaluated in each group (65 cells in vivo, 61 cells in vitro). The percentage of transferable emryos (excellent, good or fair quality), in each group also did not differ (57% in vivo, 56% in vitro). There were no significant differences in any of the measured parameters. Our findings suggest that co-culture of in vivo produced cow zygotes can result in embryos comparable in developmental stage and quality to embryos developed in vivo in the cow for 6 d.

Journal Article↗

PubMed1995

Postnatal development of the substance P-, neuropeptide Y- and serotonin-containing fibers in the rat suprachiasmatic nucleus in relation to development of the retino-hypothalamic projection.

The suprachiasmatic nucleus (SCN) in the hypothalamus controls many of the circadian rhythms in mammalian species. In the present study, we investigated the development of substance P (SP)-, neuropeptide Y (NPY)- and serotonin (5-hydroxytryptamine, 5-HT)-immunoreactive fibers in the rat SCN and the development of the retino-hypothalamic tract using cholera toxin beta subunits (CTB), in order to understand which parts of the SCN participate in diurnal rhythm regulation and entrainment. In newborn rats, SP-, NPY- and 5-HT-immunoreactive fibers were scarcely detected in the SCN. The number of SP-immunoreactive fibers gradually increased between postnatal days (P) 15 and 30. At P30, the distribution pattern of SP-immunoreactive fibers in the SCN was similar to that in the adult rat. The number of NPY- and 5-HT-immunoreactive fibers increased greatly between P10 and P15, and the increase in NPY- and 5-HT-immunoreactive fibers continued until P20. CTB was injected into the unilateral eyeball of the rat at various postnatal stages. In neonates, several labeled retinal fibers already existed in the ventral part and ventro-lateral edge of the SCN. The number and density of labeled retinal fibers in the SCN gradually increased between P10 and P20. Between P20 and P30, a decrease in the labeling was observed in the dorsolateral part of the SCN. The adult pattern of labeled retinal fibers was achieved between P20 and P30. The development of SP-immunoreactive fibers was delayed about 10 days relative to that of NPY-, 5-HT-immunoreactive fibers and retinal fibers.

Animals↗

PubMed1983

The development of the free-living stages of Strongyloides papillosus. I. Effect of temperature on the development of the heterogonic and homogonic nematodes in faecal culture.

Temperature had a significant effect on the proportion of free-living females and infective larvae of Strongyloides papillosus developing from faecal culture. The number of free-living males recovered from cultures incubated at 20 degrees C and 30 degrees C was fairly constant. However, females were most numerous at 30 degrees C and infective larvae at 20 degrees C, with the sum of the two approximately the same at both temperatures. This indicates that infective larvae and females are developing from genetically identical eggs. The critical period by which the course of development has been fixed occurs between 4 and 5 h at 30 degrees C, but between 4 and 24 h at 20 degrees C.

Animals↗

PubMed1994

Comparison between normal developing striatum and developing striatal grafts using drug-induced Fos expression and neuron-specific enolase immunohistochemistry.

The cell-level functional maturation of cell suspension grafts from embryonic day 14-15 rat striatal primordia implanted unilaterally into ibotenic acid lesioned striata of adult female rats was studied from two days to 10 weeks post-grafting. The functional and morphological characteristics of the grafts were compared with those of adult grafts (one year after implantation), normal adult striata and postnatal developing striata (up to four weeks after birth). Serial sections were stained with Cresyl Violet and investigated immunohistochemically with antibodies against dopamine- and adenosine 3',5'-monophosphate-regulated phosphoprotein (DARPP-32, as a striatal marker), tyrosine hydroxylase (as a marker of dopaminergic fibres), Fos protein (as a cell-level marker of functional dopaminergic host-graft interactions), and neuron-specific enolase (correlated to differentiation and functional maturation of neuronal cells). Selected sections were double-stained for DARPP-32 and either tyrosine hydroxylase, Fos or neuron-specific enolase. The rats used to study dopamine receptor-activated expression of Fos were killed 2 h after administration of either the dopamine-releasing agent D-amphetamine (5 mg/kg intraperitoneally) or the dopamine-receptor agonist apomorphine (0.25 mg/kg subcutaneously, at which dosage it is active only on supersensitive receptors of denervated neurons). In normally developing rats, amphetamine induced Fos expression in both the striatum and globus pallidus by two weeks after birth; by four weeks, the pattern of amphetamine-induced Fos immunoreactivity was similar to that observed in adults. In the globus pallidus of both two- and three-week-old rats, amphetamine induced greater expression of Fos than in adults. Apomorphine did not induce appreciable Fos activation in either the striatum or the globus pallidus at any stage of development. In striatal grafts, amphetamine induced Fos expression from three weeks after implantation onwards, and by five to 10 weeks post-grafting the pattern of Fos immunoreactivity was similar to that observed in adult grafts. However, apomorphine induced a considerable number of Fos-positive nuclei in striatal grafts at three and four weeks after grafting. Neuron-specific enolase immunoreactivity was moderate in normal adult striatum and very high in the adult globus pallidus, and mainly located in neuronal perikarya and processes. Before two weeks of age, most neuron-specific enolase immunoreactivity was observed in internal capsule fascicles and the striatal afferents. Between two and four weeks after birth, neuron-specific enolase immunoreactivity in striatal and globus pallidus neurons gradually increased, while that in afferent fibres decreased to adult levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗