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PubMedDate not supplied

Early development of visual cortex in human fetuses.

Prenatal development of visual cortex (area 17) was studied in human fetuses of 8-9, 13-15 and 16-18 weeks of gestation, with a view to analyse the early critical events. Under light microscope, five zones of development were seen in all the age groups. The total thickness of cortex of area 17 as well as that of its cortical plate was measured with the help of camera lucida. It was observed that the total thickness of the cortex increased with increase in age. Diversity in the shape, size, staining intensity and arrangement of neurons was noted in the different zones. Most of the cells were found to have a thin rim of cytoplasm and a prominent nucleus with multiple nucleoli. The cells in subventricular zone and cortical plate were regularly arranged in vertical rows while in other zones, they were irregularly scattered. Several mitotic figures were seen in the ventricular zone at 8-9 weeks but later they were also noticed in subventricular and intermediate zones. In the later ages the mitotic figures were observed to be fewer in the ventricular zone. No mitosis was seen in cortical plate at any age period.

Cell Division↗
PubMed2002

Early development of the adrenal glands in the grass snake Natrix natrix L. (Lepidosauria, Serpentes).

The aim of the study was to investigate the development and differentiation of the adrenal glands in the grass snake (Natrix natrix L.) during the early stages of ontogenesis, i.e., from egg-laying to hatching of the first specimens. The material used for the studies consisted of a collection of embryos of the grass snake. The Natrix eggs were incubated in the laboratory at a constant temperature of 30 degrees C and 100% relative humidity. Embryos were isolated in a regular sequence of time from egg-laying to hatching. The age of the embryos was qualified according to normal tables for this species. For histological and histochemical investigations, the smallest embryos were fixed in toto. From the oldest embryos, the medial region with the mesonephros and adrenal primordium were resected. Depending on the requirements of histochemical methods, the material was fixed in various fixatives, namely, 10% formalin solution, Bouin, Wood and Millonig fluid, embedded in paraffin and sectioned into serial transversal, sagittal and longitudinal sections. The sections for review were stained with H&E and azan. For detection of adrenaline and noradrenaline in chromaffin tissue, the Wood and Honoré methods were used. SGC cells were detected with the silver stain method after Bodian. For electron microscopic studies, the adrenal gland was fixed in 2.5% glutaraldehyde and 2.0% paraformaldehyde 1:1 in 0.1 M phosphate buffer at pH 7.4 and post-fixed in 1.5% osmic acid in the same buffer. The fixed sections of the adrenal glands were embedded in Epon 812. Semithin and ultrathin sections were cut on ultramicrotome ultratome IV. Semithin sections were stained with methylene blue and ultrathin sections were routinely contrasted with uranyl acetate and lead citrate, then examined and photographed with the JEM JEOL 1220 electron microscope. According to morphological and metrical observation in the course of the grass snake embryo development, one can distinguish 12 stages of development. The primordia of the adrenal cortex appear at the first trimester of egg incubation as two asymmetrical strands between the mesonephros and aorta dorsalis. They are made of dense mesenchymal cells. At the second trimester of development, primordia are penetrated by chromaffinoblasts and capillaries. The mesenchymal cells differentiate into interrenal cells, while chromaffinoblasts are arranged dorsally of the gland. The glands are enclosed by the capsule which separates them from the mesonephros. At the third trimester of the eggs incubation, only noradrenaline appears in a chromaffin tissue. At the moment of snake hatching, the adrenal glands are completely differentiated, both in their structure and their function. The primordia of the interrenal tissue differentiate from mesenchymal cells similarly to mammals. During the development of the snake interrenal tissue, several types of cells can be recognized, varying in the degree of differentiation and in ultrastructural features: 1. Undifferentiated cells with features of mesenchymal cells 2. Differentiating mesenchymal cells 3. Transitional cells with features of mesenchymal and steroidogenic cells 4. Differentiating interrenal cells with pleomorphic mitochondria and numerous lipid droplets 5. Embryonic interrenal cells containing circular lipid droplets and underdeveloped smooth endoplasmic reticulum 6. Transitional interrenal cells containing mitochondria with tubular and vesicular cristae, large lipid droplets, numerous myelin structures, and well-developed smooth endoplasmic reticulum 7. Degenerating cells of embryonic interrenal tissue 8. Differentiating mesenchymal cells with features of fibroblasts The above classification is very schematic and presumptive. In developing adrenal glands at the first trimester of egg incubation type 1 and 2 cells predominate. Type 3 and 4 cells were observed at the second trimester of the adrenal primordia development. At the third trimester of egg incubation, embryonic adrenal glands were composed of the type 5 cells. At the moment of snake hatching, interrenal tissue contained type 5 and 6 cells. In the next days of the adrenal gland development, at the border between the cortex and in medulla as under the capsule, numerous cells were degenerated. During the entire development period the adrenal capsule was built from type 7 cells. The chromaffin tissue of the adrenal glands is derived from the neural crest. These findings agree with the findings of all embryologists. The first chromaffinoblasts infiltrated the adrenal cortex primordium around stage IV of development. They were mixed with interrenal cells and just at hatching they were localized dorsally of the gland. The chromaffinoblasts differentiated gradually from neuron-like cells to typical chromaffinocytes. All the chromaffinoblasts contained the chromaffin granules. The size and numerical density of the chromaffin granules increased with development. Just before hatching, the cells of the chromaffin tissue contained only noradrenaline. Differentiation chromaffinoblasts into chromaffin cells are probably stimulated and controlled by the influence of hormones, which are produced by the cells of the interrenal tissue. According to morphological, histochemical and ultrastructural observation in the course of adrenal differentiation and development in the grass snake, six morphological phases can be distinguished.

Adrenal Glands↗
PubMed1998

Ripped pocket and pickpocket, novel Drosophila DEG/ENaC subunits expressed in early development and in mechanosensory neurons.

Drosophila melanogaster has proven to be a good model for understanding the physiology of ion channels. We identified two novel Drosophila DEG/ ENaC proteins, Pickpocket (PPK) and Ripped Pocket (RPK). Both appear to be ion channel subunits. Expression of RPK generated multimeric Na+ channels that were dominantly activated by a mutation associated with neurodegeneration. Amiloride and gadolinium, which block mechanosensation in vivo, inhibited RPK channels. Although PPK did not form channels on its own, it associated with and reduced the current generated by a related human brain Na+ channel. RPK transcripts were abundant in early stage embryos, suggesting a role in development. In contrast, PPK was found in sensory dendrites of a subset of peripheral neurons in late stage embryos and early larvae. In insects, such multiple dendritic neurons play key roles in touch sensation and proprioception and their morphology resembles human mechanosensory free nerve endings. These results suggest that PPK may be a channel subunit involved in mechanosensation.

Amiloride↗
PubMed1975

Cytoplasmic control of nuclear DNA synthesis during early development of Xenopus laevis: a cell-free assay.

Nuclei isolated from nondividing cells were induced to synthesize DNA by incubation with cytoplasm from early embryos of Xenopus laevis. Numerous replication eyes were formed in the nuclear DNA molecules, and high levels of [3-H]dTTP were incorporated. With this assay a protein(s) which appears to initiate DNA synthesis was found at high levels in the cytoplasm of eggs, blastulae, or gastrulae, but only at low levels in the cytoplasm of oocytes, hatched embryos, or adult tissues.

Animals↗
PubMed1996

Cellular immune responses of jirds to extracts of life cycle stages and adult excretory secretory products during the early development of Brugia pahangi.

The Brugia-jird model of lymphatic filariasis was used to examine the induction of cellular immune responses during the early premicrofilaremic phases of the infection. The intensity of the pulmonary granulomatous inflammatory response (PGRN) was determined by measuring granuloma areas around Sepharose beads coated with parasite extracts which were embolized in the lungs of jirds prior to necropsy. Necropsies were performed at 7, 14, 28, 56, and 150 days postinfection (DPI). These time points correspond to specific developmental changes in the life cycle. Lymphocyte blastogenesis assays were performed using cells from draining renal lymph nodes and splenocytes at 14 and 150 DPI. Soluble extracts of third stage larvae (L3), fourth stage larvae (L4), adult females, adult males, microfilariae (MF), and excretory secretory products (ES) of males and females were used in both measurements of cellular responsiveness. A marked granulomatous response to parasite extracts peaked at 7 DPI or 14 DPI followed by a gradual decrease to a hyporesponsive state at 120 DPI. The response of renal lymph node cells also was significantly elevated at 14 DPI and significantly decreased at > 150 DPI. The splenocyte responses were erratic and did not follow this pattern. Significant differences in PGRN responses to somatic extract preparations were not seen during the early stages of the infection (7, 14, 28 DPI), but those to MF and L3 were significantly less at 56 and 120 DPI. Although PGRN responses to ES followed a similar pattern, these were less than those to the somatic extract. The data indicated that a rapid, intense cell-mediated inflammatory response is induced early during a primary infection and that this response is rapidly downregulated. This downregulation begins prior to the maturation of adult parasites and microfilarial production. The early phase of the cellular response appears to be compartmentalized in that this response was consistently observed in the renal lymph nodes but not in the spleen. Soluble protein components of the parasites responsible for these responses are likely multiple and shared by all life cycle stages.

Animals↗
PubMed1995

Early development of the hindbrain: a longitudinal ultrasound study from 7 to 12 weeks of gestation.

Twenty-nine healthy pregnant women were examined by transvaginal ultrasound to evaluate embryonic development in vivo between 7 and 12 weeks of gestation. The rhombencephalon with its fourth ventricle, the cerebellum and the choroid plexuses of the fourth ventricle were identified and measured. The cavity of the rhombencephalon, the future fourth ventricle, was always visible from 7 weeks, initially lying superiorly in the head of the embryo. The cerebellum and the choroid plexuses of the fourth ventricle became distinguishable during week 8. The volume of the rhombencephalic cavity was estimated. The shape and size of these rhombencephalic structures, their position in relation to each other and their relation to other brain structures changed specifically during the embryonic and early fetal period. This sonoembryological development corresponded to the descriptions in classical embryological literature.

Adult↗
PubMed2001

Immunolocalization of NA(+),K(+)-ATPase in the branchial cavity during the early development of the European lobster Homarus gammarus (Crustacea, Decapoda).

We examined the ontogeny of the osmoregulatory sites of the branchial cavity in embryonic and early postembryonic stages of the European lobster Homarus gammarus through transmission electron microscopy, immunofluorescence microscopy, and immunogold electron microscopy using a monoclonal antibody IgGalpha(5) raised against the avian alpha-subunit of the Na(+),K(+)-ATPase. In mid-late embryos, Na(+),K(+)-ATPase was located along the pleurites and within the epipodite buds. In late embryos just before hatching, the enzyme was confined to the epipodite epithelia. After hatching, slight differentiations of ionocytes occured in the epipodites of larval stages. Na(+),K(+)-ATPase was also located in the ionocytes of the epipodites of larvae exposed to seawater (35.%o) and to dilute seawater (22.1 %o). After metamorphosis, the inner-side branchiostegite epithelium appeared as an additional site of enzyme location in postlarvae held in dilute seawater. Within the ionocytes, Na(+),K(+)-ATPase was mostly located along the basolateral infoldings. These observations are discussed in relation to the physiological shift from osmoconforming larvae to slightly hyper-regulating (in dilute seawater) postmetamorphic stages. The acquisition of the ability to hyper-osmoregulate probably originates from the differentiation, on the epipodites and mainly along the branchiostegites, of ionocytes that are the site of ion pumping as evidenced by the location of Na(+),K(+)-ATPase.

Animals↗
PubMed1999

Na+/K+-ATPase activity during early development and growth of an Antarctic sea urchin.

In Antarctic environments, the physiological bases for long larval life spans under natural conditions of limited food availability are not understood. The Na+ pump is likely to be involved with hypometabolic regulation in such cold environments. Changes in the activity and metabolic importance of Na+/K+-ATPase were measured in embryos of the Antarctic sea urchin Sterechinus neumayeri and in larvae reared under different feeding conditions. The rate of increase of total Na+/K+-ATPase activity was 3.9 times faster in fed than in unfed larvae. During development and growth, there was an increase in the percentage of total, potential Na+/K+-ATPase activity that was physiologically utilized. In early (10-day-old) gastrulae, 17 % was utilized in vivo, increasing to 77 % in six-arm pluteus (48-day-old) larvae. The metabolic importance of in vivo Na+/K+-ATPase activity also increased during development, accounting for 12 % of metabolic rate at day 10 and 84 % at day 48. When compared at the same enzyme assay temperature (15 degrees C), the protein-specific total Na+/K+-ATPase activities for late embryonic (prism) and early larval (pluteus) stages of S. neumayeri were 2.6 times lower than those for comparable developmental stages of two temperate sea urchin species (Strongylocentrotus purpuratus and Lytechinus pictus).

Animals↗
PubMed1998

Ion channels and early development of neural cells.

In this review we underscore the merits of using voltage-dependent ion channels as markers for neuronal differentiation from the early stages of uncommitted embryonic blastomeres. Furthermore, a fairly large part of the review is devoted to the descriptions of the establishment of a simple model system for neural induction derived from the cleavage-arrested eight-cell ascidian embryo by pairing a single ectodermal with a single vegetal blastomere as a competent and an inducer cell, respectively. The descriptions are focused particularly on the early developmental processes of various ion channels in neuronal and other excitable membranes observed in this extraordinarily simple system, and we compare these results with those in other significant and definable systems for neural differentiation. It is stressed that this simple system, for which most of the electronic and optical methods and various injection experiments are applicable, may be useful for future molecular physiological studies on the intracellular process of differentiation of the early embryonic cells. We have also highlighted the importance of suppressive mechanisms for cellular differentiation from the experimental results, such as epidermal commitment of the cleavage-arrested one-cell Halocynthia embryos or suppression of epidermal-specific transcription of inward rectifier channels by neural induction signals. It was suggested that reciprocal suppressive mechanisms at the transcriptional level may be one of the key processes for cellular differentiation, by which exclusivity of cell types is maintained.

Animals↗
PubMedDate not supplied

[The spatial-temporal distribution of the mRNA of the Na+-K+-ATPase alpha-subunit in the early development of the clawed toad studied by hybridization in situ].

Distribution of Na+-K+-ATPase alpha-subunit mRNA in full-grown oocytes and early embryos from of X. laevis has been studied using in situ hybridization on histological sections. The mRNA is dispersed about equally in the cytoplasm and is absent from the nucleus. The concentration of the mRNA is successively decreased from fertilization to the late blastula. The drastic decrease in mRNA concentration is observed in a period from morula to mid-blastula. The local increase in the mRNA concentration was detected in dorsal mesoderm and ectoderm during gastrulation.

Animals↗
PubMed1989

Localization of putative nicotinic cholinoreceptors in the early development of Paracentrotus lividus.

Experiments are described, showing the presence of putative nicotinic cholinoreceptors in the egg after fertilization. The experiments were carried out on gametes and early embryos of the sea urchin Paracentrotus lividus, by using nicotinic agonists and antagonists. 1 mM Acetylcholine (ACh), 100 microM nicotine, 100 nM alpha-bungarotoxin (alpha-BuTx) and 100 microM curare inhibit sperm motility and fertilization, while they have no effect on unfertilized eggs. The drugs added within 1 min. after the raising of the fertilization layer had stronger effects on cleavage and development; when added more than 15 min. after the raising of the fertilization layer, they had lesser effects on further development up to pluteus stage. In all the experiments, nicotine was the most effective drug. The binding of fluorescein-labelled alpha-BuTx did not point out any affinity sites on unfertilized eggs, while they were localized on the sperms and on the eggs fertilized by sperms, but not on the eggs activated artificially. The binding was prevented by pretreatment of sperms and activated eggs with 10 nM native alpha-BuTx and 10 microM curare. We conclude that, in the fertilized egg, putative nicotinic cholinoreceptors are present, which are able to bind alpha-BuTx and curare. Fertilization by sperms is needed to trigger the formation of alpha-BuTx receptors.

Animals↗
PubMed1996

Ultrastructural study of ensheathing cells in early development of olfactory axons.

Ultrastructural observations in the grey short-tailed opossum (Monodelphis domestica) and rat revealed that ensheathing cells were intimately related to the early formation of olfactory axons. Whilst the axons were still in the olfactory epithelium, they were enveloped by ensheathing cell processes which formed a cradle-like structure on the basal side of the epithelium. Continued downgrowth of the axons towards the lamina propria resulted in an evagination with the ensheathing cell process or cell body in direct contact with the basal lamina. Subsequently the basal lamina became fragmented, and the newly formed olfactory nerve emerged from the olfactory epithelium. As the olfactory nerve grew, it was observed that the ensheathing cell process always extended ahead of the axons while axon terminals moving ahead of ensheathing cells were never observed. The findings in this study suggest that ensheathing cells play a role in regulating and promoting olfactory axon growth.

Animals↗
PubMed2006

Early development of critical illness myopathy and neuropathy in patients with severe sepsis.

OBJECTIVES: To characterize the prevalence, time of onset, and cause of neuromuscular dysfunction in patients with severe sepsis. METHODS: We conducted a prospective cohort study in which participants with severe sepsis underwent weekly neurologic examinations and nerve conduction studies (NCSs) within 72 hours of developing severe sepsis until intensive care unit (ICU) discharge. Electromyography was preformed if clinical weakness developed or if there was a significant reduction in nerve conduction response amplitudes. RESULTS: Abnormal NCS were present upon enrollment in 63% of patients (31/48). The presence of abnormal baseline NCS was predictive of hospital mortality (55% vs 0% for patients with normal baseline NCS; p < 0.001). Development of acquired neuromuscular dysfunction could be predicted by NCS done on day 7. Twenty patients remained in the ICU long enough to have serial NCSs; 50% of these patients developed acquired neuromuscular dysfunction. Most patients with acquired neuromuscular dysfunction had electrophysiologic evidence of both critical illness myopathy and critical illness neuropathy. CONCLUSION: Changes in nerve conduction studies occur in the majority of patients early in the course of severe sepsis and predict the development of acquired neuromuscular dysfunction and mortality in intensive care unit patients. Most patients with acquired neuromuscular dysfunction after sepsis have both critical illness myopathy and critical illness neuropathy.

Adult↗
PubMed2005

Telomerase expression in noncancerous bronchial epithelia is a possible marker of early development of lung cancer.

Centrally located lung cancers in smokers frequently associated with subsequent primary tumors. We evaluated the telomerase expression chronologically in noncancerous epithelia as a risk factor of susceptibility to lung cancer development. Telomerase protein expression was examined in situ by immunohistochemistry in 26 noncancerous bronchial epithelia adjacent to centrally located early-stage lung cancers in sequential 23 patients treated by photodynamic therapy or surgery among 206 patients who underwent autofluorescence bronchoscopy from 1997 to 2003. Among the 15 lesions in 12 patients treated by photodynamic therapy alone, 11 lesions achieved complete remission after photodynamic therapy, and none of their noncancerous bronchial epithelia was telomerase positive. On the contrary, in the remaining four lesions, either recurrence or secondary lung cancer developed adjacent to the successfully treated primary cancer within 26 months, and the telomerase protein expression in noncancerous epithelia was detected before the secondary cancer development (P < 0.001). The overall relationship of human telomerase reverse transcriptase positivity in noncancerous epithelia and subsequent lung cancer development, including patients treated by radiation or surgery, showed higher significance (P < 0.0001). Histologically "normal" bronchial epithelia in smokers may unphysiologically express telomerase as a field, and such epithelia are likely susceptible to develop lung cancer. We propose that ectopic expression of telomerase in bronchial epithelia may precede transformation in human lung cancer development and that detection of telomerase protein in noncancerous bronchial epithelia will become a useful marker detecting high-risk patients for lung cancer development.

Biomarkers, Tumor↗
PubMed1999

Intracellular Ca2+ oscillations drive spontaneous contractions in cardiomyocytes during early development.

Activity of cardiac pacemaker cells is caused by a balanced interplay of ion channels. However, it is not known how the rhythmic beating is initiated during early stages of cardiomyogenesis, when the expression of ion channels is still incomplete. Based on the observation that early-stage embryonic stem cell-derived cardiomyocytes continuously contracted in high extracellular K+ solution, here we provide experimental evidence that the spontaneous activity of these cells is not generated by transmembrane ion currents, but by intracellular [Ca2+]i oscillations. This early activity was clearly independent of voltage dependent L-type Ca2+ channels and the interplay between these and ryanodine sensitive Ca2+ stores. We also show that intracellular Ca2+ oscillations evoke small membrane depolarizations and that these can trigger L-type Ca2+ channel driven action potentials.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2002

Circulating monocyte chemoattractant protein-1 and early development of nephropathy in type 1 diabetes.

OBJECTIVES: To investigate the possible role of hyperglycemia-dependent monocyte chemoattractant protein (MCP)-1 biosynthesis in the pathophysiology of early nephropathy in type 1 diabetes. RESEARCH DESIGN AND METHODS: We studied 30 patients with type 1 diabetes (15 with and 15 without microalbuminuria) compared with matched healthy control subjects. Plasma MCP-1 and plasma oxidant status (vitamin E, fluorescent products of lipid peroxidation [FPLPs], malondialdehyde [MDA]), HbA(1c), and albumin excretion rate [AER]) were evaluated at baseline. Furthermore, MCP-1, vitamin E, AER, and HbA(1c) were also analyzed in the microalbuminuric diabetic patients and in the healthy volunteers after 8 weeks of high-dose (600 mg b.i.d.) vitamin E treatment. RESULTS: FPLPs, MDA, and MCP-1 were significantly higher, whereas vitamin E was significantly lower in patients with microalbuminuria and poorer glycemic control as compared with normoalbuminuric patients and healthy control subjects. Plasma MCP-1 was positively correlated with HbA(1c), FPLPs, MDA, and AER, whereas plasma MCP-1 showed an inverse correlation with vitamin E. Interestingly, both MCP-1 and AER decreased significantly after vitamin E treatment, despite no changes in HbA(1c) values. CONCLUSIONS: This study suggests that prolonged hyperglycemia may lead to early renal complications in type 1 diabetes by inducing MCP-1 biosynthesis via enhanced oxidative stress. Long-term treatment of high-dose vitamin E significantly decreased MCP-1, thus providing a rationale basis for evaluating vitamin E supplementation as therapy adjuvant to conventional insulin treatment in type 1 diabetic patients in whom an acceptable glycemic control is difficult to achieve despite appropriate insulin treatment.

Adult↗