Ultrasonic monitoring of early development of lower vertebrate embryos

We have investigated whether the neuromeres of the developing chick spinal cord (myelomeres) are manifestations of intrinsic segmentation of the CNS by studying the patterns of cell proliferation and neuronal differentiation. Treatment of 2-day embryos with colchicine does produce exaggerated myelomeres, in confirmation of Kallen (Z. Anat. Entwickl.-Gesch. 123, 309–319, 1962). However, this does not imply that myelomeres are segmental proliferation centres: the undulations caused by colchicine are irregular alongside the unsegmented mesoderm, and another mitotic inhibitor, bromodeoxyuridine, has no such effects. In contrast to lower vertebrate embryos, there is no evidence for segmental groups of primary motor neurons in the chick: the earliest motor neurons express cholinesterase, and project their axons into the adjacent sclerotome, at random positions in relation to the somite boundaries. The population of motor neurons projecting HRP-labelled axons into a single somite lies out of phase with both myelomere and somite, and is placed symmetrically about the anterior half-sclerotome. The earliest intrinsic spinal cord neurons, as stained with zinc iodide-osmium tetroxide or anti-68 × Mr neurofilament antibody, show no segmental patterns of differentiation. We conclude that, in contrast to the rhombomeres of the developing hindbrain, myelomeres are not matched by segmental groupings of differentiating nerve cells, and result from mechanical moulding of the neuroepithelium by the neighbouring somites.

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Reproduction and the Early Development of Vertebrates in Space: Problems, Results, Opportunities

Life ◽

10.3390/life11020109 ◽

2021 ◽

Vol 11 (2) ◽

pp. 109

Author(s):

Alexandra Proshchina ◽

Victoria Gulimova ◽

Anastasia Kharlamova ◽

Yuliya Krivova ◽

Nadezhda Besova ◽

...

Keyword(s):

Developmental Biology ◽

Cell Proliferation ◽

Early Development ◽

Space Flight ◽

Morphological Changes ◽

Vertebrate Development ◽

The Moon ◽

Adaptive Changes ◽

Space Flights ◽

Vertebrate Embryos

Humans and animals adapt to space flight conditions. However, the adaptive changes of fully formed organisms differ radically from the responses of vertebrate embryos, foetuses, and larvae to space flight. Development is associated with active cell proliferation and the formation of organs and systems. The instability of these processes is well known. Over 20 years has passed since the last systematic experiments on vertebrate reproduction and development in space flight. At the same time, programs are being prepared for the exploration of Mars and the Moon, which justifies further investigations into space flight’s impact on vertebrate development. This review focuses on various aspects of reproduction and early development of vertebrates in space flights. The results of various experiments on fishes, amphibians, reptiles, birds and mammals are described. The experiments in which our team took part and ontogeny of the vertebrate nervous and special sensory systems are considered in more detail. Possible causes of morphological changes are also discussed. Research on evolutionarily and taxonomically different models can advance the understanding of reproduction in microgravity. Reptiles, in particular, geckos, due to their special features, can be a promising object of space developmental biology.

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Memoirs: The Early Development of Astropecten Irregularis, with Remarks on Duplicity in Echinoderm Larvae

Journal of Cell Science ◽

10.1242/jcs.s2-69.275.519 ◽

1925 ◽

Vol s2-69 (275) ◽

pp. 519-554

Author(s):

H. G. NEWTH

Keyword(s):

Early Development ◽

Normal Development ◽

Bilateral Symmetry ◽

Mechanical Deformation ◽

Insufficient Evidence ◽

Vertebrate Embryos ◽

Pore Canals

I. (1) The normal development of Astropecten irregularis is described up to the twenty-fifth day. (2) About a third of the larvae possessed two pore-canals, and larval twinning was observed in two cases. II. There is insufficient evidence for believing that normal Echinoderm larvae possess a ‘latent’ bilateral symmetry. III. The following provisional conclusions are reached regarding duplicity in Echinoderm larvae: (1) The various kinds of duplicity form a series. (2) They are of the same nature as those found in vertebrate embryos, and are probably due to similar causes. (3) They may be determined by (a) Alteration of the polarity of the egg ; (b) Interference with processes of early development affecting gastrulation ; (c) Physiological inhibition or mechanical deformation of the tip of the archenteron. (4) Their ultimate facies, in the case of (c), is determined largely by excess or defect of nutrition.

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Individual differences, social attention, and the history of the social motivation hypotheses of autism

Behavioral and Brain Sciences ◽

10.1017/s0140525x18002509 ◽

2019 ◽

Vol 42 ◽

Author(s):

Peter C. Mundy

Keyword(s):

Individual Differences ◽

Early Development ◽

Emotional Development ◽

Social Motivation ◽

Social Attention ◽

Social Emotional Development ◽

Social Emotional ◽

Precise Understanding ◽

The Social ◽

History Of

Abstract The stereotype of people with autism as unresponsive or uninterested in other people was prominent in the 1980s. However, this view of autism has steadily given way to recognition of important individual differences in the social-emotional development of affected people and a more precise understanding of the possible role social motivation has in their early development.

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Classical social reward signatures in infants with later ASD

Behavioral and Brain Sciences ◽

10.1017/s0140525x18002492 ◽

2019 ◽

Vol 42 ◽

Author(s):

Teodora Gliga ◽

Mayada Elsabbagh

Keyword(s):

Early Development ◽

Social Motivation ◽

Self Report ◽

Social Reward ◽

Socially Motivated

Abstract Autistic individuals can be socially motivated. We disagree with the idea that self-report is sufficient to understand their social drive. Instead, we underscore evidence for typical non-verbal signatures of social reward during the early development of autistic individuals. Instead of focusing on whether or not social motivation is typical, research should investigate the factors that modulate social drives.

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Early Development of Drug-Induced Hepatic Necrosis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066942 ◽

1971 ◽

Vol 29 ◽

pp. 576-577

Author(s):

F. G. Zaki ◽

E. Detzi ◽

C. H. Keysser

Keyword(s):

Early Development ◽

Hepatic Necrosis ◽

Screening Tests ◽

Dense Matrix ◽

Sprague Dawley ◽

Electron Microscopic ◽

Drug Induced ◽

Hepatocellular Damage ◽

Sprague Dawley Rats ◽

Microscopic Studies

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.

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Ultrastructural Changes of Smoooth Endoplasmic Reticulum in the Retinal Pigment Epithelium by Choline Chloride

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100093547 ◽

1972 ◽

Vol 30 ◽

pp. 58-59

Author(s):

Kazushige Hirosawa ◽

Eichi Yamada

Keyword(s):

Endoplasmic Reticulum ◽

Epithelial Cell ◽

Smooth Endoplasmic Reticulum ◽

Pigment Epithelium ◽

Choline Chloride ◽

Retinal Pigment ◽

Ultrastructural Changes ◽

Lower Vertebrate ◽

Visual Cells ◽

Pigment Epithelial

The pigment epithelium is located between the choriocapillary and the visual cells. The pigment epithelial cell is characterized by a large amount of the smooth endoplasmic reticulum (SER) in its cytoplasm. In addition, the pigment epithelial cell of some lower vertebrate has myeloid body as a specialized form of the SER. Generally, SER is supposed to work in the lipid metabolism. However, the functions of abundant SER and myeloid body in the pigment epithelial cell are still in question. This paper reports an attempt, to depict the functions of these organelles in the frog retina by administering one of phospholipid precursors.

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The early development of antenna and antennal sensilla in the noctuid moth, Agrotis segetum (Insecta: Lepidoptera)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160066 ◽

1990 ◽

Vol 48 (3) ◽

pp. 502-503

Author(s):

Eric Hallberg ◽

Lina Hansén

Keyword(s):

Cell Death ◽

Stem Cell ◽

Early Development ◽

Larval Stage ◽

Pupal Stage ◽

Agrotis Segetum ◽

Antennal Sensilla ◽

Noctuid Moth ◽

Standard Procedures

The antennal rudiments in lepidopterous insects are present as disks during the larval stage. The tubular double-walled antennal disk is present beneath the larval antenna, and its inner layer gives rise to the adult antenna during the pupal stage. The sensilla develop from a cluster of cells that are derived from one stem cell, which gives rise to both sensory and enveloping cells. During the morphogenesis of the sensillum these cells undergo major transformations, including cell death. In the moth Agrotis segetum the pupal stage lasts about 14 days (temperature, 25°C). The antennae, clearly seen from the exterior, were dissected and fixed according to standard procedures (3 % glutaraldehyde in 0.15 M cacaodylate buffer, followed by 1 % osmiumtetroxide in the same buffer). Pupae from day 1 to day 8, of both sexes were studied.

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Live Confocal Analysis of Fertilization and Early Development

Microscopy and Microanalysis ◽

10.1017/s1431927600031135 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 1012-1013

Author(s):

Uyen Tram ◽

William Sullivan

Keyword(s):

Drosophila Melanogaster ◽

Embryonic Development ◽

Real Time ◽

Early Development ◽

Fluorescent Probes ◽

Primary Defect ◽

Fluorescent Analysis ◽

Dynamic Event ◽

Enormous Amount ◽

Fluorescent Studies

Embryonic development is a dynamic event and is best studied in live animals in real time. Much of our knowledge of the early events of embryogenesis, however, comes from immunofluourescent analysis of fixed embryos. While these studies provide an enormous amount of information about the organization of different structures during development, they can give only a static glimpse of a very dynamic event. More recently real-time fluorescent studies of living embryos have become much more routine and have given new insights to how different structures and organelles (chromosomes, centrosomes, cytoskeleton, etc.) are coordinately regulated. This is in large part due to the development of commercially available fluorescent probes, GFP technology, and newly developed sensitive fluorescent microscopes. For example, live confocal fluorescent analysis proved essential in determining the primary defect in mutations that disrupt early nuclear divisions in Drosophila melanogaster. For organisms in which GPF transgenics is not available, fluorescent probes that label DNA, microtubules, and actin are available for microinjection.

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