摘要:

AbstractThe subsarcolemmal cisternae of the sarcoplasmic reticulum form peripheral couplings with the sarcolemma. The junctional gap is crossed by periodic densities called junctional processes. Desmosomes provide mechanical coupling between the myofibres. Hemidesmosomes connect the myofibre with a well developed connective tissue sheath.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00253.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe diploid number 44 has been determined, with reserve, for the echinoidCidaris cidaris, thus further supporting the hypothesis that the phylum Echinodermata is characterized by an astonishing stability of chromosome numbers. The spermatogonial chromosomes ofC. cidarisare very minute and heterocyclic elements are absent.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00254.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe structure of the sarcotubular systems of the caudal muscle cells is described in various larvaceans. InOikopleurathere is both a transverse tubular system and a sarcoplasmic reticulum; there are internal couplings between the two and also sarcolemmal couplings. InFritillaria(and probably also inKowalevskaia), a transverse tubular system is lacking, and there are only sarcolemmal couplings with the sarcoplasmic reticulum, which is related to the mitochondria as well as to the myofilaments. The significance of these differences is discussed, and it is concluded that the arrangement of the sarcotubular systems is related to muscle fibre thickness; within the Tunicata, these systems do not indicate phylogenetic relationships.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractUltrastructural observations of the rod‐shaped organ inCypridina norvegicaandParaconchoecia elegansindicate homology with the organ of Bellonci of other crustaceans. InC. norvegicathe organ is situated close to the ventral cup of the nauplius eye. Distally in the organ, several ciliary ramifications of the sensory neurons protrude into internal cavities formed by bordering cells. Six dendrites, with cell bodies within and in front of the brain, form the proximally bifurcated nerve, which enters the protocerebrum in the region of the medullae terminales. In this species the organ represents the deep receptor of the organ of Bellonci complex. InP. elegansthe external part of the organ is situated between the proximal parts of the antennulae. Four dendrites in two groups emerge from the protocerebrum. Distally, they form branching cilia that are in close contact which the cuticle of the organ, thus forming a receptor similar to the superficial receptor of the organ of Bellonci complex of other crustaceans. It is suggested that the terms frontal organ and rod‐shaped organ be abandoned in favour of the term organ of Bello

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn the blood ofMyxine glutinosathree cell lines may be distinguished: erythrocytes, granulocytes and agranulocytes. The erythrocytes are remarkably large, oval and nucleated. They are well defined in all their developmental stages by a characteristic micropinocytosis. They originate from blast cells which proliferate in the circulating blood. The blast cells probably form from agranulate stem cells of the intestinal myeloid tissue. The granulocytes constitute about half of the leucocytes. They are neutrophilic with a lobated nucleus. The granulocytopoiesis takes place in the intestinal myeloid tissue. The agranulocytes mainly include two cell types, termed spindle cells and lymphocyte‐like cells. These cell types, however, transform into each other. Macrophages occur essentially in the peritoneal cavity rarely in the blood. Transition forms between macrophages and granulocytes may exist. The blood also contains cells which on morphological grounds have been termed thrombocytes. Whether these cells are identical with those necessary for clotting of the blood remains to be proved. With the exception of erythroblasts, the different lines of blast cells are difficult to identify and distinguish from each other. Possibly all lines of blood cells originate from agranulate lymphocyte‐like stem cells, most of which are produced by the intestinal myeloid tis

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00257.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe development of the spermatogenetic stages in the testis of the hagfishEptatretus burgeriwas studied by means of histological techniques. These animals have an annual reproductive cycle with a spawning season in October. Spermatocytes begin to appear in January and reach a maximum in March. The development of spermatids of stage I and stage II starts in April and June, respectively. In August about 35% of the testicular follicles contain spermatids of stage II. The gonadosomatic index shows a more or less constant increase from November until August. During the spawning season, no animals with well developed testis could be trapped. About 10% of male hagfish bear undeveloped gonads.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00258.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe “rhizoidsrdquo; surrounding the base of the erect “colony” emanating from the ancestrula in the Crisiidae, especially the simple speciesCrisidia cornuta(L.), are a regular adnate system of autozooids. Each autozooid is composed of a proximal adnate part and a distal peristome (in some species kenozooids are possibly intercalated). The autozooid peristomes support erect branches identical in budding and structure with the branch emanating from the erect peristome of the ancestrula. Thus, the complete crisiid colony consists of an adnate system of ancestrula and autozooids, which form erect branches from their peristomes. The adnate zooid system is comparable in autozooid morphology and budding pattern with simple uniserial stomatoporids. The tentative hypothesis is proposed that the crisiid group has developed from primitive stomatoporids; the adnate zooid system of the stomatoporids apparently evolved peristomial budding to produce the erect colony branches characteristic of cri

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00259.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe olfactory organ of tench is functionally divided in a vestibule and a gallery. Experimental observations are presented indicating that an unidirectional watercurrent is created from the vestibule to the gallery via the corridors which are formed by the leaves of the olfactory rosette. The conditions for creating the watercurrents are: oriented and symmetrical beats of cilia situated on the walls of the corridors, and appropriate spacing of the corridors. This principle for water sampling is found in the olfactory organs of trout, carp, roach, catfish, eel, rockling and dogfish. In some other fishes studied the olfactory organs have accessory olfactory sacs and there is no subdivision in vestibule and gallery. In these organs the watercurrents are achieved by a pumping mechanism of the sacs.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1977.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY