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C S Goodman

Publications and source records attributed to C S Goodman.

At least 163 records · Page 9Linked to original sources
PubMed1986

Guidance of neuronal growth cones in the grasshopper embryo. II. Recognition of a specific axonal pathway by the aCC neuron.

In the previous paper, we experimentally analyzed the selective affinity of the pCC growth cone for the MP1/dMP2 fascicle in the grasshopper embryo. Here we describe a similar experimental analysis demonstrating the selective affinity of the aCC growth cone for the U fascicle. These results support the labeled-pathways hypothesis. The 2 sets of cell ablation experiments argue against the simple location of axons, the simple timing of axon outgrowth, and/or simple quantitative differences in the expression of a common surface label being the major determinant in pathway selection by neuronal growth cones. Rather, these 2 examples of growth-cone specificity, together with previous studies on the G growth cone, suggest that neuronal recognition molecules are differentially expressed on the surfaces of different embryonic axonal pathways and tracts and are used to guide growth cones through a series of choice points to their targets.

Animals↗
PubMed1986

Guidance of neuronal growth cones in the grasshopper embryo. III. Recognition of specific glial pathways.

In the previous 2 papers, we focused on the selective affinities that growth cones display for specific axonal pathways. Little is known, however, about how this orthogonal scaffold of axonal pathways in the CNS is established in the first place, and what, if any, role glia might play in these events. Here we show an important relationship between pioneering growth cones and primitive glial cells in the developing longitudinal connectives and peripheral nerve roots of the grasshopper embryo. We describe a preformed glial pathway for the formation of the intersegmental nerve, one of the major roots exiting the CNS. The growth cones that pioneer this nerve display a selective affinity for the segment boundary cell (SBC), a primitive glial cell that establishes the location of this nerve root. Similar glial cells are also found along the pathway where the longitudinal connectives form, and they too may play an important role in the formation of the first longitudinal axonal pathways. Experimental analysis shows that when the SBC is ablated, the growth cones that normally turn laterally to pioneer the intersegmental nerve do not do so, thus confirming the importance of the guiding role of this glial cell. We postulate that a simple orthogonal scaffold of primitive glia is involved in the initial patterning of axonal pathways within and exiting the insect CNS; this concept is remarkably similar to the blueprint hypothesis proposed by Singer et al. (1979) to explain the development of axon pathways in vertebrates.

Animals↗
PubMed1986

Guidance of neuronal growth cones in the grasshopper embryo. IV. Temporal delay experiments.

In the previous 3 papers, we demonstrated that neuronal growth cones display selective affinities for both specific axonal and glial pathways in the grasshopper embryo; for example, the pCC growth cone selectively recognizes the MP1/dMP2 axons, while the aCC growth cone selectively recognizes the U axons and a specific glial cell (the segment boundary cell). We were interested in further testing the temporal specificity of these affinities. To address this issue, we performed specific temporal transplant experiments by using a laser microbeam in ovo to ablate the neuronal precursor cell, neuroblast (NB) 1-1, that generates the aCC and pCC neurons. Neighboring ectodermal cells regulate and replace the ablated NB 1-1; the new NB 1-1 then generates the aCC and pCC neurons with a temporal delay of 10-20 hr (2-4% of development), depending upon the experimental paradigm. The results of these temporal delay experiments further demonstrate the selective affinities of the aCC and pCC growth cones for specific axonal and glial surfaces and confirm that these specificities are absolute and not hierarchical. Furthermore, they suggest that precise timing is not important; both the pCC and aCC growth cones are able to selectively recognize their appropriate axonal and glial pathways after delays of 10-20 hr despite being confronted with the surfaces of many additional axons and pathways.

Animals↗
PubMed1985

From epithelium to neuroblasts to neurons: the role of cell interactions and cell lineage during insect neurogenesis.

The grasshopper central nervous system is composed of a brain and a chain of segmental ganglia. Each hemiganglion contains about 1000 neurons, most of which can be individually identified by their unique morphology and synaptic connectivity. Shortly after gastrulation the ventral ectoderm becomes a neurogenic region. In each hemisegment, ca. 150 neurogenic ectodermal cells (nECs) give rise to a stereotyped pattern of 30 identified neuroblasts (NBs, neuronal stem cells); the remaining nECs become various non-neuronal cells or die. The 30 NBs then give rise to about 1000 neurons as each NB initiates an invariant lineage, generating a stereotyped chain of ganglion mother cells (GMCs), each of which in turn divides once to generate two identified neurons. We have used a laser microbeam or microelectrode to ablate individual cells in ovo and in vitro at various stages of embryogenesis to study how neuronal diversity and specificity are generated during development. Our results suggest that cell interactions between ca. 150 equivalent nECs allow 30 cells to enlarge into NBs, the dominant fate in a hierarchy; the NBs inhibit adjacent nECs and thus cause them to differentiate into various non-neuronal cells; each NB is assigned its unique identity according to its position of enlargement within the neurogenic epithelium; each NB then generates its characteristic chain of GMCs by an invariant cell lineage; and each GMC generates a pair of equivalent progeny, the fate of each individual neuron being determined by both its GMC of origin and interactions with its sibling.

Cell Communication↗
PubMed1985

Heterogeneous properties of segmentally homologous interneurons in the ventral nerve cord of locusts.

The G, B1, and B2 neurons are three prominent interneurons located in adjacent segmental ganglia in the central nervous system of locusts. Previous studies on the adult nervous system have shown that each of these cells has its own distinctive morphology and responsiveness to auditory input. Previous studies on the embryonic nervous system have described the lineage and development of one of these cells, the G neuron, in the mesothoracic (T2) segment. In this paper it is shown that the G, B1, and B2 neurons are segmental homologues in that they arise from equivalent lineages during embryogenesis in the T2, T3, and A1 segments, respectively. Each cell arises (along with its identified sibling neuron) from the division of the second ganglion mother cell of neuroblast 7-4. The segment-specific morphology of the G homologues was determined in the T3 and A1 segments between 60-70% of embryonic development, and their identity was established as the adult B1 and B2 neurons by comparing the distinctive cell-specific features of their morphology between embryo and adult. Although all three neurons display striking morphological differences, they all share certain structural features in common, including the location of their primary axons and neurites in specific tracts in the neuropil. By recording intracellularly from the main neurites of the G, B1, and B2 neurons, clear differences were found in the synaptic inputs each of the neurons receives and the synaptic outputs each makes. For example, G and B2, but not B1, receive direct monosynaptic input from the descending contralateral movement detector (DCMD) interneurons and from auditory afferents; B1, but not B2, connects directly to G; and B2, but not B1 or G, connects directly to flight motoneurons. The main conclusion from these observations is that lineally equivalent neurons in different segments can develop similar primary structures but quite different secondary morphologies and synaptic connections. How these segment-specific differences arise during embryogenesis remains unknown.

Animals↗
PubMed1985

Neuronal determination during embryonic development of the grasshopper nervous system.

We have examined the roles of cell lineage and interactions in the determination of individual identified neurons in the grasshopper embryo by selective ablations of individual cells and/or their neighbors at successive stages following their birth. The neurons in the grasshopper central nervous system (CNS) are produced by two types of identifiable neuronal precursor cells: neuroblasts (NBs), which generate most of the neurons, and midline precursors (MPs), which generate only a few. NBs divide asymmetrically in a stem cell fashion to generate a chain of ganglion mother cells (GMCs) which then divide once more symmetrically to produce pairs of sibling neurons: MPs cleave once to generate a single pair of sibling neurons. We analyzed the determination of (1) the pair of sibling progeny produced by midline precursor 3 (MP3) and the determination of (2) the pair of sibling progeny produced by the first GMC from neuroblast 1-1 (NB 1-1); in each case the siblings normally differentiate into morphologically distinct neurons. Our results indicate that both pairs of neuronal progeny (1) are born equivalent, (2) become determined by cell interactions early in their development before axonogenesis, and (3) demonstrate a hierarchy of fates with one fate dominant over the other. These results suggest a common pattern of neuronal determination in the grasshopper and possibly all insect embryos.

Animals↗
PubMed1985

Early events in insect neurogenesis. I. Development and segmental differences in the pattern of neuronal precursor cells.

The earliest events in the development of the central nervous system in insect embryos involve the differentiation of a stereotyped pattern of individually identified neuronal precursor cells, called neuroblasts (NBs), each of which generates a stereotyped family of neuronal progeny. After gastrulation, the midventral region of the ectoderm becomes a neuroepithelium; it is from this sheet of seemingly uniform ectodermal cells that certain cells enlarge to become NBs while the rest of the cells either die or acquire other nonneuronal phenotypes. Here we focus on three aspects of neurogenesis. First, we examine the morphological changes associated with the differentiation of neuronal precursor cells and nonneuronal support cells. The differentiation of each cell type is reflected by its morphology; moreover, the identity of individual cells of certain cell types (e.g., a particular NB) is reflected by their position within the neuroepithelium. Second, we show that there is a characteristic temporal sequence of differentiation in the stereotyped pattern of NBs. Third, we show that this stereotyped pattern of NBs varies in a segment-specific way by the addition or deletion of particular neuronal precursor cells. These studies on the events of early neurogenesis set the stage for the experimental manipulations described in the following paper (C. Q. Doe and C.S. Goodman, 1985, Dev. Biol. 110, 206-219).

Abdomen↗
PubMed1985

Early events in insect neurogenesis. II. The role of cell interactions and cell lineage in the determination of neuronal precursor cells.

The insect central nervous system (CNS) is composed of a brain and a chain of segmental ganglia; each hemiganglion contains about 1000 individually identifiable neurons. How is the enormous neuronal diversity and specificity generated? Neurons of a hemiganglion largely arise during embryogenesis from a stereotyped pattern of individually identified neuronal precursor cells, called neuroblasts (NBs). The transition from ectoderm to individual neurons thus involves two major steps: first, an undifferentiated ectodermal cell sheet produces the stereotyped pattern of 30 NBs per hemisegment; second, each of these NBs contributes a specific family of neuronal progeny to the developing CNS. We have used a laser microbeam to ablate individual cells in the grasshopper embryo in order to study the initial events of neuronal determination. In particular, how does a layer of apparently equivalent ectodermal cells produce a highly stereotyped pattern of unique NBs? Our results suggest the following mechanism for NB determination. (1) Cell interactions between the approximately 150 equivalent ectodermal cells of a hemisegment allow 30 cells to enlarge into NBs. (2) As these young NBs enlarge they inhibit adjacent ectodermal cells from becoming NBs; the adjacent cells then either differentiate into nonneuronal support cells or die. (3) Each NB is assigned a unique identity due to its position of enlargement within the neuroepithelium. (4) The NB then generates its characteristic family of neurons by an invariant cell lineage. Development of the insect CNS depends on cell interactions and positional cues to create a pattern of NBs, and then on cell lineage to restrict the fate of the NB progeny.

Animals↗
PubMed1985

Muscle development in the grasshopper embryo. I. Muscles, nerves, and apodemes in the metathoracic leg.

Much is known about the development of nerve pathways in the metathoracic limb bud of the grasshopper embryo. In this series of three papers, we report on the development of muscles in the same embryonic appendage. In a fourth paper (E. E. Ball, R. K. Ho, and C. S. Goodman, 1985, J. Neurosci, in press) we examine the development of specific neuromuscular connections for one of these muscles (coxal muscle 133a). In this first paper, we present an overview of the development of muscles, nerves, and apodemes (tendons). We previously reported on a class of large mesodermal cells, called muscle pioneers (MPs), that arises early in development and appears to act as a scaffold for developing muscles and guidance cue for motoneuron growth cones (R. K. Ho, E. E. Ball, and C. S. Goodman, 1983, Nature (London) 301, 66-69). We have used the I-5 monoclonal antibody (which specifically labels the MPs as well as the nerve pathways), HRP immunocytochemistry, and Normarski optics to visualize muscle, nerve, and apodeme development in the embryonic metathoracic limb bud from 27.5% (before the appearance of the MPs) to 55% (after the muscles have attained their basic adult pattern). Cell fusions, cell migration, and cell death all appear to play important roles in the development of MPs. The patterns of muscle development vary greatly, ranging from (i) single MPs for simple muscles (which in the adult have only one bundle of muscle fibers, e.g., coxal muscle 133a), to (ii) arrays of MPs for complex muscles [which in the adult have many bundles of muscle fibers each with separate sites of insertion, e.g., the extensor tibiae (ETi) and flexor tibiae (FlTi) muscles in the femur].

Animals↗
PubMed1985

Muscle development in the grasshopper embryo. II. Syncytial origin of the extensor tibiae muscle pioneers.

The extensor tibiae muscle (ETi) in the metathoracic leg of the grasshopper, which powers the jump, is among the most studied insect muscles. In contrast to many insect muscles which are simple (consisting of only a single bundle of muscle fibers), the ETi is a complex muscle which consists of an array of bundles of muscle fibers, each with a separate site of insertion on the body wall ectoderm and on the ETi apodeme ectoderm. Here we describe the embryonic development of this complex muscle. The ETi muscle develops from a single muscle pioneer (MP) which connects the initial invagination of the ETi apodeme to the wall of the femur. This MP then dramatically expands around the developing apodeme to form a large horseshoe-shaped, multinucleate cell, called the supramuscle pioneer (supra-MP); the number of nuclei in the supra-MP increases by cell fusion rather than by nuclear division. The arms of the supra-MP grow steadily longer and their outer edges begin to appear scalloped, certain areas remaining tightly apposed to the ectoderm of the wall of the leg while adjacent areas lose their adhesion and are pulled away. By about 50% of embryonic development the ETi supra-MP consists of a periodic series of bridges (cytoplasmic extensions) connecting the leg wall ectoderm with the apodeme, and linked into a giant syncytium near their inner, apodeme surface by a thin layer of cytoplasm containing hundreds of nuclei. Each bridge is surrounded by a cluster of many smaller mesoderm cells. Next the syncytium begins to divide such that by 60% the periodic bridges of the supra-MP have lost syncytial contact with each other and now themselves form an array of smaller, individual, multinucleate MPs connecting the body wall to the apodeme, each surrounded by a mass of undifferentiated mesoderm cells. This initial cycle of fusion and division is followed by a second similar cycle in which the individual mesoderm cells surrounding each MP fuse with the MP. At the same time, the MP divides into the initial bundle of smaller muscle fibers. Coincident with this division into muscle fibers is the further development of thick and thin filaments and the T-tubule system.

Animals↗
PubMed1985

Muscle development in the grasshopper embryo. III. Sequential origin of the flexor tibiae muscle pioneers.

The flexor (FlTi) and extensor (ETi) tibiae are antagonist muscles located in the femur of the metathoracic leg of the grasshopper. Both are complex, consisting of an array of bundles of muscle fibers connecting the ectoderm of the wall of the femur with their respective apodemes. In the previous paper (E. E. Ball and C. S. Goodman, 1985, Dev. Biol. 111, 399-416) we described the embryonic development of the ETi muscle, focusing in particular on its syncytial origin from a giant supramuscle pioneer which later divides into an array of individual muscle pioneers. Here we describe the embryonic development of the FlTi muscle. In contrast to the development of the ETi muscle, the array of individual muscle pioneers for the FlTi does not have a syncytial origin but rather arises by sequential recruitment from the mass of smaller, undifferentiated mesoderm cells. The FlTi MPs first appear as two cells symmetrically placed on the corners of the FlTi apodeme at around 37%. A third MP is then added between these two; this third MP later dies. Subsequent growth occurs by symmetrical addition of MPs distally along the sides of the developing apodeme and by enlargement of the individual MPs. Initially each MP contains only a single nucleus; by about 50% there are at least two to three nuclei per MP and each is surrounded by a cluster of smaller, undifferentiated mesoderm cells. Each MP develops into a bundle of muscle fibers by a cycle of fusion and division. The individual mesoderm cells surrounding each MP fuse with it starting at about 60%. At the same time, the large MP begins to divide into smaller muscle fibers.

Animals↗
PubMed1985

Development of neuromuscular specificity in the grasshopper embryo: guidance of motoneuron growth cones by muscle pioneers.

In the grasshopper embryo, neuromuscular specificity develops between individual identified motoneurons whose cell bodies are located in the central nervous system, and specific skeletal muscles in the periphery. We previously reported on a class of large mesodermal cells, called muscle pioneers (MPs), that arise early in development (Ho, R. K., E. E. Ball, and C. S. Goodman (1983) Nature 301: 66-69). We suggested that the MPs might be involved in orchestrating the coordinated development of nerve and muscle. In this paper, we describe the development of the MP for coxal muscle 133a in the metathoracic limb bud, and its innervation by two excitatory motoneurons (fast, Df, and slow, Ds). Although many motoneuron growth cones extend out of nerve 5 and quite likely come in contact with the 133a MP between 35% and 45% of development, only Df and Ds display a high affinity for its surface; the other motoneurons innervate more distal leg muscles. When the 133a MP is ablated before arrival of motoneurons in the limb bud, the Df growth cone extends past the location where it normally gets off nerve 5 and continues to extend distally along the same pathway taken by its sibling motoneuron. Although there is a mass of small mesodermal cells in the area where the differentiated coxal muscle 133a normally forms, evidently it does not provide the necessary guidance cue for the Df growth cone. These results indicate the important role played by MPs in the specific guidance of motoneuron growth cones in the grasshopper embryo.

Grasshoppers↗
PubMed1984

Cell recognition during neuronal development.

Insect embryos, with their relatively simple nervous systems, provide a model system with which to study the cellular and molecular mechanisms underlying cell recognition during neuronal development. Such an approach can take advantage of the accessible cells of the grasshopper embryo and the accessible genes of Drosophila. The growth cones of identified neurons express selective affinities for specific axonal surfaces; such specificities give rise to the stereotyped patterns of selective fasciculation common to both species. These and other results suggest that early in development cell lineage and cell interactions lead to the differential expression of cell recognition molecules on the surfaces of small subsets of embryonic neurons whose axons selectively fasciculate with one another. Monoclonal antibodies reveal surface molecules in the Drosophila embryo whose expression correlates with this prediction. It should now be possible to isolate the genes encoding these potential cell recognition molecules and to test their function through the use of molecular genetic approaches in Drosophila.

Animals↗
PubMed1984

Neuronal growth cones: specific interactions mediated by filopodial insertion and induction of coated vesicles.

We are interested in the factors that guide individual neuronal growth cones during embryonic development. Here we report on the discovery of a highly specific interaction between developing growth cones in the grasshopper embryo as revealed by transmission electron microscope serial-section reconstructions. Numerous filopodia from an identified growth cone (MP1) insert deep within another identified growth cone (pCC), inducing the formation of coated pits and vesicles. This interaction is highly specific, since filopodia from other nearby growth cones that contact the surface of the two interacting neurons neither penetrate them nor induce coated vesicles. These specific filopodial interactions may play an important role in the subsequent development of these neurons.

Animals↗
PubMed1984

From embryonic fascicles to adult tracts: organization of neuropile from a developmental perspective.

We discuss ideas emerging from our studies on selective axonal fasciculation in the grasshopper embryo that have implications for the organization of the adult neuropile in insects and perhaps other animals. While one of our laboratories has been studying the embryonic development of the G neurone (in the mesothoracic segment) and its lineal homologues (in other segments), the other has been studying the morphology and physiology of this same neurone and its segmental homologues in the adult nervous system. Our embryonic studies show that the growth cone of the G neurone selectively fasciculates with the A/P fascicle in preference to all other longitudinal axon fascicles at it turns anteriorly. The homologues of G in other thoracic and abdominal segments fasciculate in this same bundle. However, early in their morphological differentiation, they reveal interesting segmental differences. Our studies on the adult nervous system show that the segmental homologues of the G neurone share many properties in common (e.g. axons in the LDT: lateral dorsal tract) while other features are quite different. The notion emerging from these studies is that a basic segmentally-repeated pattern arises during embryogenesis: a stereotyped axonal scaffold upon which growth cones faithfully fasciculate. Evolutionary plasticity allows the specialization of lineally equivalent neurones in different segments within the context of the neuropilar neighbourhood that they find themselves in as a consequence of their selective fasciculation.

Animals↗
PubMed1984

Cell determination and differentiation of identified serotonin-immunoreactive neurons in the grasshopper embryo.

We have begun to investigate the factors that underlie neurotransmitter determination in the central nervous system of the grasshopper embryo. The most prominent serotonin-immunoreactive neurons in the segmental ganglia are three clonally related interneurons, cells S1, S2, and S3. S1 and S2 are sibling neurons and are the first two born in the family of neurons that is produced by neuroblast 7-3; cell S3 derives from one of the second-born pair in the same family. S1 is serotonin-immunoreactive in all thoracic and abdominal segments, S2 in all but two segments (T3 and A1), and S3 in only the prothorax (T1). These segment-specific differences are not due to differential cell death but rather can be ascribed to biochemical differences between lineally homologous neurons. Furthermore, these homologous neurons also display interesting segment-specific differences in their morphology. Laser ablation of neuroblast 7-3 before it begins its series of programmed cell divisions results in the absence of its normal serotonin-immunoreactive neuronal progeny when screened at mature stages. These experiments support the hypothesis that transmitter determination is at least in part regulated by cell lineage in the grasshopper embryo and that some clonally related neurons appear to share a common transmitter determination by virtue of their common lineage. The results further suggest that cell lineage regulation of transmitter determination may vary according to segment or may be modified by as yet unidentified segment-specific factors.

Animals↗