摘要:

AbstractThe nephridium of the dwarf male ofBonellia viridiswas investigated by means of transmission electron microscopy. The nephridium proved to be of a distinct protonephridial type and not a metanephridium as maintained in the older literature. The nephridium is composed of a ciliated duct that projects into the coelom. Five crown cells at the end of the duct function as terminal filtration cells. Each crown cell has a bundle of about 20 cilia, surrounded by a labyrinthic weir of cell processes that are presumably involved in filtration. The ciliary bundles enter the nephridial duct through perforations of the adjacent tubule cells. This finding of a protonephridium in a minute, coelomate animal that lacks a circulatory system corroborates a recently formulated functional theory on the distribution of nephridial types.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01174.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe organization of the dwarf male ofBonellia viridiswas studied by electron microscopy. The epidermis is formed by two types of epithelial cells: the majority are multiciliated cells; highly vacuolated, non‐ciliated cells are less abundant. The body wall musculature consists of an outer circular, a diagonal, and a longitudinal layer. As a unique feature in coelomate spiralians it was found that the perikarya of all muscle cells are located internal to the entire contractile muscular layer. The muscles are solitary myocytes embedded in extracellular matrix. Masses of secretory and indifferent cells occur inside the muscles. Two types of secretory cells were distinguished. Both of them apparently undergo holocrine secretion. A complete lining of thin peritoneal cells delimits the body cavity. Also, the gut and sperm sac have a complete peritoneal lining. The coelomic lining of the gut is a single‐layered myoepithelium, that of the sperm sac a pseudo‐stratified myoepithelium. The vas deferens was seen to be ciliated. The entrance of the sperm sac is formed by a ciliated funnel that leads into the reservoir by means of a thin, ciliated canal. The existence of repeated transverse nerves and of four longitudinal nerve cords is described for the first

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01175.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractWe performed an investigation at the light microscopical level of the differential distribution of lectin‐binding sites among cells of the epidermis and glandular domains of the African clawed frogXenopus laevis. Using a panel of biotinylated lectins (Con‐A. PSA, LCA, UEA‐I, DBA, SBA, SJA, RCA‐I, BSL‐I, WGA, s‐WGA, PHA‐E and PHA‐L) and an avidin–biotin–peroxidase complex (ABC), we have identified specific binding patterns.The results show that expression of saccharide moieties inXenopusepidermal keratinocytes is related to the stage of cellular differentiation, different cell layers expressing different sugar residues. Moreover, oliogosaccharides with “identical” biochemically defined sugar compositions can be distinguished. The method allowed further characterization of complex glycoconjugates of dermal glands. In view of these results, the ABC technique and the biotinylated lectins employed in the present study are believed to be a reliable method for the precise localization of saccharide residues of glycoconjugates present in

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01176.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe internal architecture of the limbate setae ofSabella penicillus(Sabellidae) is described, based on transmission and scanning electron microscopy. The setae are composed of a number of cylindrical channels (mean= 877). The number of channels is less than one third of the number of spines on the distal swollen part of the setae. In the proximal shaft, channels are hollow and cylindrical. Towards the expanded distal part of the setae, the lumen gradually disappears, and the shape of the wall of the channels changes from circular to hexagonal. With no lumen, the term microrod is suggested as more descriptive than ‘channel’ for the units in this part of the seta. The solid microrods change from a strictly hexagonal shape to a more irregular indented shape, and gradually taper off towards the tip region. The cortical layer of the expanded part contains numerous irregular cavities. Morphometric data on the organization of the internal components are presented. When tested for flexibility, the setae broke when bent to a mean of 93.6° (±9°). Calculations based on morphometry show that the bending stiffness is up to 19 times greater in the swollen part than in the shaft, and it is reduced to about 1/50 in the dista

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01177.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractInArmina maculatathe heart lies anteriorly and has a large muscular ventricle and a delicate auricle running obliquely to the antero‐posterior axis. The auriculoventricular valve and the aortic valve are disposed at the anterior end of the auricle and ventricle respectively. The aortic trunk is located just anterior to the ventricle and gives off several arteries, which extend through the whole body. The main arteries are: the cephalic artery (to the buccal apparatus); the posterior artery (to the notum, digestive glands, ovotestis and renal chamber); the pedal artery (to the foot); and the genital arteries (supplying the different organs of the reproductive system). These data are compared with those of other arminacean specie

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01178.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the spermatozoon ofGeogarypus nigrimanus(Arachnida, Pseudoscorpionida) is described. The spermatozoon is composed of a small elliptic nucleus, a short flagellum and a very long and complex acrosome. In the male genital ducts, as in other studied species of pseudoscorpions, the sperm components are rolled up to form a globular structure enclosed in a cyst wall. TheGeogarypusspermatozoon with a reduced flagellum and a giant acrosome seems to be evolutionary more advanced than spermatozoa from other pseudoscorpions.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01179.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractEarlier papers dealing with the anatomy of the amphinomid brain were studied. Discrepancies in the studied works prompted a re‐investigation of the central nervous system of these animals. In this paper the brain commissures, the clusters of ganglion cells and the innervation of the antennae, the palps and the nuchal organs ofEurythoe complanata, Amphinome rostrata, Pherecardia striata, andNotopygos variabilisare described in some detail. The brain ofHermodice carunculatais studied more cursorily. The results, summarized in schematic diagrams, are compared with corresponding observations of the brains of ‘spiomorphic’ and ‘serpulimorphic’ polychaetes and to information given by earlier authors about structures in the Nereidiformia and Aphroditiformia. Using the major Remanian criteria for identifying homologies, equivalents in the amphinomid brain and the central nervous systems of some ‘sedentary’ and ‘errant’ families are proposed. As a consequence, some earlier opinions about the morphological value of the cephalic appendages of the amphinomids are strengthened while others are rejected. The necessity of further investigations of the polycheaete nervous sys

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1990.tb01180.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY