摘要:

AbstractProblems concerning terminology and relationships of basement membranes to extracellular matrices (ECMs) and connective tissue systems in invertebrates are discussed, and recommendations regarding nomenclature are presented. It is suggested to use ‘basal matrix’ as a comprehensive term for various basal ECM structures, and apply the term ‘basement membrane’ (BM) for a unique ECM structure that is fully resolved only by electron microscopy and as a general and descriptive word in both light microscopy, biochemistry and electron microscopy. When possible and relevant it is recommended to apply the subdivisions: ‘lamina lucida’, ‘lamina densa’ (= ‘basal lamina’) and ‘lamina fibroreticularis’ (sometimes missing). A brief and non‐technical account of the recent concepts of BM macromolecules and their assembly is given, based on mammalian models. Basement membranes probably first appeared in cnidarians, and from then on became obligatory ECM structures. It is emphasized that this event was crucial for evolution of the multicellular state, and for construction and morphogenesis of tissues and organs. Lower worms, such as turbellarians and nemertines, display the most varied and complex basal matrices. First, in annelids, complete correlation between BM structure and composition has been demonstrated, with isolation and consecutive localization of basement‐specific molecules such as, for example, collagen IV and laminin. Both in arthropods, especially insects, and echinoderms, the introduction of modern techniques corresponding to those used in mammalian BM research has now given equally valid results. An interesting and fundamental outcome of the reviewed work on invertebrate BMs is the realization of the early evolution of BM components. Macromolecules such as laminin, collagen IV and fibronectin are highly conserved, but with fine modulations, and in lower invertebrates they may exist without being assembled into true BM structures. Laminin and fibronectin are expressed with certainty in cnidarians, and fibronectin

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01196.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAdults of the European lancelet were collected at Banyuls‐sur‐Mer (Mediterranean France) in mid‐spring, shortly before the onset of the breeding season. The dorsal and ventral fin rays were studied by light microscopic histochemistry and by transmission electron microscopy (TEM). Each fin ray is a mass of extracellular material that accumulates beneath the mesothelium of a fin box coelom. The fin ray material is rich in lipids, proteins, and neutral mucopolysaccharides. TEM reveals no lipid droplets in this material, which consists entirely of a packed mass of 15–20 nm granules of medium electron density. It is likely that these granules consist of glycoproteins or glycolipoproteins. Our results are consistent with the proposal of Azariah (1965,Journal of the Marine Biological Association of India7: 459–661) that lancelet fin rays are nutritional reserves supporting gametogenesis during the breedi

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01197.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe thymus of the soleSolea soleacontained lymphoblasts and thymocytes within a network of pale and dark epithelial cells. The pale cells were characterized by tonofilaments and desmosomes and some embraced rodlet cells within their cytoplasmic processes. The dark epithelial cells had numerous electron‐dense inclusions and electron‐lucent vacuoles. Lymphocytes were closely associated with the plasma membrane of both types of epithelial cells and with macrophages. Breakdown of effete lymphocytes appeared to be the main function of the macrophages. Some macrophages were multinucleated. Those containing melanin granules associated with phagosomes were classified as melanomacrophages. Pigment cells including melanophores and guanophores were present along the connective tissue trabeculae and surrounding the blood vessels. A few plasma cells and mucous cells were pres

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01198.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractVarious horseradish peroxidase‐conjugated lectins have been used for the ultrastructural localization of carbohydrate moieties of glycoconjugates on plasma membranes of the surface cells ofBlennius sanguinolentusepidermis.Concanavalia ensiformis(Con A),Arachis hypogaea(PNA),Pisum sativum(PSA) andUlex europaeus(UEA I) lectins bind only to the outermost plasma membranes, the glycocalyx and the intercellular spaces of the surface cells. Other lectins applied, such asTriticum vulgare(WGA),Glycine max(SBA) andGriffonia simplicifolia(GS I), presenting GlcNAc and GaINAc specificity, reacted with the plasma membranes of basolateral domains and gave an attenuated reaction with the outermost plasma membranes. The results suggest that regional differences exist in the distribution patterns of GlcNAc and GalNAc‐terminating glycoconjugates. The possible implication of the polarized expression of these glycoconjugates in ion transport is discus

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01199.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe term vomer was coined over four centuries ago to denote one of the 23 bones normally comprising an adult human skull. As time went on more and more craniates were designated vomerate. To date, however, the issue as to whether brachiopterygian fish are or are not vomerate has remained unresolved. Those who consider these fish to be vomerate have suggested at least three different palatal bones as the homologue of the human vomer. Examination of embryological material ofPolypterus senegalusshows that this brachiopterygian actually develops a vomer which eventually becomes united indistinguishably with the anterior part of the parasphenoid. The vomer is suggested to have arisen through the fusion of dental plates belonging to a supplementary set of buccopharyngeal denticulate bones. The other subethmoidal bones of the brachiopterygian palate seem likely to be derivatives of the tooth plates which originally were applied to the first two pairs of infrapharyngeals. When these endoskeletal elements were put to use for encapsulation of the organs of smell early in craniate phylogeny, some of the tooth plates that covered their inner surfaces fused to provide anterior palatal bones. Identified at one time or another as vomers, these bones are here termed glochinals and dacnils.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01200.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractEarlier papers dealing with the innervation and homologues of the anterior end appendages of some aphroditacean families were re‐studied. However valuable these earlier works may be, in some respects they proved to be insufficient for detailed comparisons with other polychaete families and some of their statements are quite contradictory. This prompted a re‐investigation of the central‐most parts of the nervous system of representatives of the families Polynoidae, Sigalionidae, Aphroditidae and Acoetidae. In the present paper, the brain commissures and the innervation of,inter alia, the antennae, the palps and the ommatophores (when present) inLepidonotus squamatus, Harmothoe longisetis, Leanira (Sthenolepis) tetragona, Laetmonice producta benthaliana, andPanthalis oerstediare described. Special attention is paid to the much‐debated question about the presence or absence of a palp ganglion. The results, summarized in schematic diagrams, are compared with corresponding observations of the brains of, above all, the ‘spiomorphic’ polychaetes. Using the first Remanian criterion for identifying homologies, equivalents in the aphroditacean brain and the central nervous system of ‘sedentary’ families are proposed. By this a broader base is established for the discussion regarding the fundamental constitution of the anterior end of the polychaetes and the structure and homologues of their ceph

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01201.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe running speed ofAgama stellio stelliowas 2.1 ± 0.3 m s−1at preferred body temperature (Tb, 30°C). To account for sprint locomotion, we meaured two mechanical parameters and examined the ultrastructural features of a major locomotory muscle in normal walking and running locomotion, the iliofibularis muscle, which is considered to act as an extensor of the lower hind limb. The time to peak isometric twitch tension and time to half relaxation were 52 ± 7 ms and 76 ± 5 ms, respectively.The comparative ultrastructure of the fast and slow fibes provides structure‐to‐function correlation. The sarcoplasmic reticulum and T‐tubules system are abundant in fast fibres which serve to transmit Ca2+and spread the excitatory impulse intracellularly with great rapidity. In contrast, the membranous system of slow fibres is relatively poor and this indicates slow impulse propagation. Thus, these results show that the fast locomotion ofAgama stellio stelliocan, in part, be explained by the physiology and ultrastructure of the fibres of the locomot

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01202.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractOikopleura dioicahas two large subchordal cells which were studiedin vivoand with light and electron microscopy. They have fixed positions within the haemocoel of the tail but change their morphology continually by protruding and withdrawing processes in an amoeboid manner. Also the fine structure varies considerably from one animal to the next. The cell surface sometimes indicates a strong pinocytotic activity with many coated pits and vesicles. In other cases there are many small vesicles which are interpreted as exocytotic. They are found both in the cytoplasm close to the plasma membrane and in the haemocoelic fluid. Subchordal cells with no pronounced surface activity have a large amount of rough endoplasmic reticulum, which suggests that they synthesize proteins. The presence of subchordal cells in the tail is correlated with the presence of the ontogenetically related bioluminescent oral gland cells in the pharynx; either both types exist simultaneously or both are lacking. It is speculated that the two cell types are also functionally co‐ordinated.Oikopleura albicanshas a multitude of tiny subchordal cells which have essentially the same fine structure as the two largeOikopleura dioicacell

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1991.tb01203.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY