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Biomedical subjects

D M Noden

Publications and source records attributed to D M Noden.

At least 37 records · Page 2Linked to original sources
PubMed1988

Ontogeny of architectural complexity in embryonic quail visceral arch muscles.

Understanding the mechanisms of muscle pattern formation requires that the complete sequence of ontogenetic events be defined, particularly in the emergence of architectural complexity and in the spatial relations between muscles and skeletal elements. This analysis of visceral arch myogenesis in quail (Coturnix coturnix japonica) embryos identifies the location of premuscle condensations and subsequent segregation of individual muscles, documents the initial orientation of myofibers and changes in alignment associated with maturation, and describes the spatial and temporal relations between muscle development and the formation of connective tissues. Premuscle condensations form within the visceral arches on embryonic days 2-4, before skeletal elements make their appearance. Discrete muscles may form from the subdivision of a muscle mass after fiber orientations have been established (e.g., jaw adductor and hyobranchial muscles) or by the segregation of a mesenchymal cluster from the condensation prior to the appearance of oriented fibers (e.g., protractor, muscle of the columella). The rate and pattern of subsequent muscle maturation are closely associated with the development of the hard tissues. Myogenesis in 4-9-day embryos centers around the quadrate cartilage, the retroarticular process of the mandibular (Meckel's) cartilage, and the epibranchial cartilage. Muscles form attachments on these elements and remain without additional attachments until the appropriate elements (e.g., otic capsule, pterygoid bone) develop. No single description of myogenic events applies to all visceral arch muscles, nor is there an arch-specific pattern of ontogeny. Rather, each muscle has distinctive characteristics based on its spatial relations within the developing head.

Animals↗
PubMed1988

Interactions and fates of avian craniofacial mesenchyme.

Craniofacial mesenchyme is composed of three mesodermal populations - prechordal plate, lateral mesoderm and paraxial mesoderm, which includes the segmented occipital somites and the incompletely segmented somitomeres - and the neural crest. This paper outlines the fates of each of these, as determined using quail-chick chimaeras, and presents similarities and differences between these cephalic populations and their counterparts in the trunk. Prechordal and paraxial mesodermal populations are the sources of all voluntary muscles of the head. The latter also provides most of the connective precursors of the calvaria, occipital, otic-parietal and basisphenoid tissues. Lateral mesoderm is the source of peripharyngeal connective tissues; the most rostral skeletal tissues it forms are the laryngeal and tracheal cartilages. When migrating neural crest cells encounter segmented paraxial mesoderm (occipital and trunk somites), most move into the region between the dermamyotome and sclerotome in the cranial half of each somite. In contrast, most cephalic crest cells migrate superficial to somitomeres. There is, however, a small subpopulation of the head crest that invades somitomeric mesoderm. These cells subsequently segregate presumptive myogenic precursors of visceral arch voluntary muscles from underlying mesenchyme. In the neurula-stage avian embryo, all paraxial and lateral mesodermal populations contain precursors of vascular endothelial cells, which can be detected in chimaeric embryos using anti-quail endothelial anti-bodies. Some of these angioblasts differentiate in situ, contributing directly to pre-existing vessels or forming isolated, nonpatent, cords that subsequently vesiculate and fuse with nearby vessels. Many angioblasts migrate in all directions, invading embryonic mesenchymal and epithelial tissues and participating in new blood vessel formation in distant sites. The interactions leading to proper spatial patterning of craniofacial skeletal, muscular, vascular and peripheral neural tissues has been studied by performing heterotopic transplants of each of these mesodermal and neural crest populations. The results consistently indicate that connective tissue precursors, regardless of their origin, contain spatial information used by the precursors of muscles and blood vessels and by outgrowing peripheral nerves. Some of these connective tissue precursors (e.g. the neural crest, paraxial mesoderm) acquire their spatial programming while in association with the central nervous system or developing sensory epithelia (e.g. otic, optic, nasal epithelia).

Animals↗
PubMed1986

Patterning of avian craniofacial muscles.

Vertebrate voluntary muscles are composed of myotubes and connective tissue cells. These two cell types have different embryonic origins: myogenic cells arise from paraxial mesoderm, while in the head many of the connective tissues are formed by neural crest cells. The objective of this research was to study interactions between heterotopically transplanted trunk myotomal cells and presumptive connective tissue-forming cephalic neural crest mesenchyme. Presumptive or newly formed cervical somites from quail embryos were implanted lateral to the midbrain of chick hosts prior to the onset of neural crest emigration. Hosts were sacrificed between 7 and 12 days of incubation, and sections examined for the presence of quail cells. Some grafted tissues differentiated in situ, forming ectopic skeletal, connective, and muscle tissues. However, many myotomal cells broke away from the implant, became integrated into adjacent neural crest mesenchyme, and subsequently formed normal extrinsic ocular or jaw muscles. In these muscles it was evident that only the myogenic populations were derived from grafted trunk cells. Ancillary findings were that grafted trunk paraxial mesoderm frequently interfered with the movement of neural crest cells which form the corneal posterior epithelial and stromal tissues, and that some grafted cells formed ectopic intramembranous bones adjacent to the eye. These results verify that presumptive connective tissue-forming mesenchyme derived from the neural crest imparts spatial patterning information upon myogenic cells that invade it. Moreover, interactions between myotomal cells and both lateral plate somatic mesoderm in the trunk and neural crest mesenchyme in the head appear to operate according to similar mechanisms.

Animals↗
PubMed1986

Inherited homeotic midfacial malformations in Burmese cats.

During the past three decades, Burmese cats have been selected for a shorter muzzle and a more rounded face. Recently there arose a line of these animals that consistently exhibit such a brachycephalic appearance; unfortunately, approximately 25% of these kittens are born with a neonatal lethal midfacial malformation. The abnormality is characterized by agenesis of all derivatives of the medial nasal prominence; lateral duplication of most derivatives of the maxillary process; including the canine teeth and whiskers fields; telencephalic meningoencephalocele; and secondary ocular degeneration. The anatomy, embryology, and pattern of inheritance of this unique midfacial malformation are described.

Abnormalities, Multiple↗
PubMed1986

Origins and patterning of craniofacial mesenchymal tissues.

Three mesenchymal tissues participate in the formation of orofacial tissues; these are the neural crest, paraxial mesoderm, and lateral mesoderm. Interactions both among these populations and between them and surrounding epithelial tissues are an essential feature of facial development. Perturbation of these interactions may result in craniofacial malformations and dysmorphologies. This review outlines the origins and early morphogenetic movements of each of the three mesenchymal populations, then describes experiments which reveal some of the interactions that control their development. Spatial organization within cephalic mesenchyme is manifest initially in connective tissue precursors. In the facial region these are derived from the neural crest; in contrast, much of the neurocranium is derived from paraxial mesoderm. Most crest populations become spatially programmed prior to their emergence from the neuroepithelium, presumably during the primary induction of the neural plate. As they migrate to form the branchial arches, the crest populations bring spatial information to these peripheral regions. Connective tissue-forming populations within cephalic paraxial mesoderm display a similar inherent spatial programming, but it is not known when or how they acquire this information.

Animals↗
PubMed1983

Contributions of placodal and neural crest cells to avian cranial peripheral ganglia.

The method of embryonic tissue transplantation was used to confirm the dual origin of avian cranial sensory ganglia, to map precise locations of the anlagen of these sensory neurons, and to identify placodal and neural crest-derived neurons within ganglia. Segments of neural crest or strips of presumptive placodal ectoderm were excised from chick embryos and replaced with homologous tissues from quail embryos, whose cells contain a heterochromatin marker. Placode-derived neurons associated with cranial nerves V, VII, IX, and X are located distal to crest-derived neurons. The generally larger, embryonic placodal neurons are found in the distal portions of both lobes of the trigeminal ganglion, and in the geniculate, petrosal and nodose ganglia. Crest-derived neurons are found in the proximal trigeminal ganglion and in the combined proximal ganglion of cranial nerves IX and X. Neurons in the vestibular and acoustic ganglia of cranial nerve VIII derive from placodal ectoderm with the exception of a few neural crest-derived neurons localized to regions within the vestibular ganglion. Schwann sheath cells and satellite cells associated with all these ganglia originate from neural crest. The ganglionic anlagen are arranged in cranial to caudal sequence from the level of the mesencephalon through the third somite. Presumptive placodal ectoderm for the VIIIth, the Vth, and the VIIth, IXth, and Xth ganglia are located in a medial to lateral fashion during early stages of development reflecting, respectively, the dorsolateral, intermediate, and epibranchial positions of these neurogenic placodes.

Animals↗
PubMed1983

The embryonic origins of avian cephalic and cervical muscles and associated connective tissues.

The objective of these experiments was to determine the embryonic origins of craniofacial and cervical voluntary muscles and associated connective tissues in the chick. To accomplish this, suspected primordia, including somitomeres 3-7, somites 1-7, and cephalic neural crest primordia have been transplanted from quail into chick embryos. Quail cells can be detected by the presence of a species-specific nuclear marker. The results are summarized as follows: (table; see text) These results indicate that muscles associated with branchial arch skeletal structures are derived from paraxial mesoderm, as are all other voluntary muscles in the vertebrate embryo. Thus, theories of vertebrate ontogeny and phylogeny based in part on proposed unique features of branchiomeric muscles must be critically reappraised. In addition, many of these cephalic muscles are composites of two separate primordia: the myogenic stem cells of mesodermal origin and the supporting and connective tissues derived from the neural crest or lateral plate mesoderm. Defining these embryonic origins is a necessary prerequisite to understanding how the mesenchymal primordia of cephalic muscles and connective tissues interact to form patterned, species-unique musculoskeletal systems.

Animals↗
PubMed1983

The role of the neural crest in patterning of avian cranial skeletal, connective, and muscle tissues.

The morphology of skeletal tissues formed in each of the branchial arches of higher vertebrates is unique. In addition to these structures, which are derived from the neural crest, the crest-derived connective tissues and mesodermal muscles also form different patterns in each of the branchial arches. The objective of this study was to examine how these patterns arise during avian embryonic development. Presumptive second or third arch neural crest cells were excised from chick hosts and replaced with presumptive first arch crest cells. Both quail and chick embryos were used as donors; orthotopic crest grafts were performed as controls. Following heterotopic transplantation, the hosts developed several unexpected anomalies. Externally they were characterized by the appearance of ectopic, beak-like projections from the ventrolateral surface of the neck and also by the formation of supernumerary external auditory depressions located immediately caudal to the normal external ear. Internally, the grafted cells migrated in accordance with normal, second arch pathways but then formed a complete, duplicate first arch skeletal system in their new location. Squamosal, quadrate, pterygoid, Meckel's, and angular elements were present in most cases. In addition, anomalous first arch-type muscles were found associated with the ectopic skeletal tissues in the second arch. These results indicate that the basis for patterning of branchial arch skeletal and connective tissues resides within the neural crest population prior to its emigration from the neural epithelium, and not within the pharynx or pharyngeal pouches as had previously been suggested. Furthermore, the patterns of myogenesis by mesenchymal populations derived from paraxial mesoderm is dependent upon properties inherent to the neural crest.

Animals↗
PubMed1980

Somatotopic and functional organization of the avian trigeminal ganglion: an HRP analysis in the hatchling chick.

While the somatotopic organization of many central systems is well characterized, that of peripheral sensory neurons has not been adequately defined. This is especially true for the trigeminal ganglion. By applying HRP subcutaneously at each of 14 sites and also intramuscularly, it is possible to determine whether the location of sensory neurons within the ganglion reflects their peripheral projections. There is no discernible somatotopic organization of neurons in the ophthalmic lobe. However, the location of maxillary neurons in the maxillo-mandibular lobe is organized with the most posterior cells projecting to sites closest to the ganglion and with neurons located more anteriorly projecting to progressively more distant sites. There is a less well defined organization in the superior-inferior axis of the ganglion, and none along its proximal (root) to distal axis. Mandibular exteroceptive neurons are found primarily in the anterior region of the maxillo-mandibular lobe, while mandibular proprioceptive cells are located in the proximo-central part of this lobe. In most cases there is a considerable scattering of horseradish peroxidase (HRP)-filled neurons. Projections to contralateral ganglia, the trigeminal motor nucleus, and the trigeminal mesencephalic nucleus were also examined. Cytologically, the hatchling trigeminal consists of two interspersed types of neurons: large, lightly staining and smaller, darkly staining cells. Previous experiments have proved that these two cell types do not correspond to each of the embryonic precursors of trigeminal neurons, the neural crest and placodal cells. In this study HRP was found localized in both classes of neurons following injection at all sites, including jaw-closing muscles. This indicates that the dual cytology is not correlated with either distribution of peripheral fibers or exteroceptive vs. proprioceptive functions. The possibilities that the two types of neurons may have different central projections and/or may be related to visceral vs. somatic afferent functions are discussed.

Animals↗
PubMed1980

Somatotopic organization of the embryonic chick trigeminal ganglion.

Horseradish peroxidase (HRP) has been injected into periocular, upper beak, or lower jaw tissues of chick embryos aged 6--8 days of incubation. Subsequent mapping of the distribution of labeled neurons in the trigeminal ganglion indicates that the somatotopic organization of neurons is essentially identical to that found after hatching. At these stages most labeled cells are in the distal parts of the bilobed ganglion. There is no indication that any of these neurons, most but not all of which are derived from epidermal placodes, establish any erroneus projections. Most of the proximo-central or core neurons, which are of neural creast origin, are immature at these stages. On the eighth day of development, by which time the embryo is responsive to tactile stimulation of the beak, few of these core cells have established projections to more distal (rostral) periocular or upper beak areas or to the lower jaw. In contrast, injection of HRP above the eye results in labeling of many of the core neurons. This suggests that there is an asymmetry in the time of neurite outgrowth from core neurons that is correlated with their peripheral projections but not with their time of terminal mitosis. Following injection of HRP into temporal periocular tissues, most of the core cells in the maxillo-mandibular lobe contain peroxidase. This is probably due to uptake by growth cones emerging along the maxillary ramus. Examination of contralateral trigeminal ganglia indicates that the transmedian projections of these sensory fibers form later in development. Branches of the mandibular motor nerve extend throughout the lower jaw and presumptive jaw-closing muscle anlagen, as evidenced by incorporation of HRP into motoneurons of the trigeminal nucleus.

Animals↗
PubMed1980

An autoradiographic analysis of the development of the chick trigeminal ganglion.

The avian trigeminal ganglion, which is embryonically derived from the neural crest and epidermal placodes, consists of two topographically segregated classes of immature neurons, large and small, during the second week of incubation, and two neuronal cell types, dark and light, interspersed throughout the mature ganglion. In order to establish the times of terminal mitosis of trigeminal sensory neurons, embryos were treated with [3H]thymidine during the first week of incubation and their ganglia fixed on embryonic day 11. The embryonically large, distal, placodal-derived neurons are generated between days 2 and 5, while the small, proximal, neural crest-derived neurons are formed mostly between days 4 and 7. By comparing the locations of labeled cells in ganglia treated with isotope but fixed on day 18 of incubation with their 11-day counterparts, we have proved that there are no morphogenetic rearrangements of neurons during the final week of incubation. Thus, no unique relationship exists between the two neuron types in the mature ganglion and the two cell classes in the immature trigeminal. Therefore, both the light and the dark neurons in the mature trigeminal ganglion arise from neural crest as well as placodal primordia.

Animals↗