Volker Storch

The fine structure of the digital pads of rhacophorid tree frogs

SummaryThe digital pads of three tree-frogs (genus Rhacophorus) have been studied by transmission and scanning electron microscopy. The distal parts of the outermost epidermal cells are separated by wide gaps. The surface of these cells is characterized by stout microvillus-like processes. The apical plasma membrane is reinforced by a layer of electron-dense material attached to its inner side. The cytoplasm contains bundles of tonofilaments extending into the apical cellular processes, numerous ribosomes and abundant granular and vesicular inclusions. In the connective tissue under the epidermis mucous glands — characterized by granule-containing, mitochondria-rich and smooth muscle cells — and an extensive nerve plexus occur. The latter innervates the mucous glands and in addition consists of sensory fibres which have been found in connection with lamellated sensory corpuscles. In respect of the degree of adaption towards a tree-dwelling life, the excluvisely tree inhabiting species (Rhacophorus reinwardti) appears to be particularly advanced.

Ultrastruktur-Untersuchungen am männlichen Genitaltrakt und an Spermien vonTetranychus urticae (Tetranychidae, Acari)

SummaryThe paired testes of the spider miteTetranychus urticae are divided in a part producing germ cells and a secretory portion with a vast lumen. The secretory part is tubular and is connected to a vesicula seminalis that begins with paired pieces and then becomes unpaired. The penis is composed of two different parts: an evagination of the body wall that is penetrated by the ejaculatory duct and a ventral cuticular invagination the proximal part of which is an insertion for protractor muscles.The ultrastructures of the male genital tract and of the receptaculum seminis of the female are described in detail.The germinal epithelium is built up of a multinuclear somatic cell which envelops the germ cells. The spermiogenesis is characterized by the following features: invagination of the plasma membrane, degeneration of cell organelles, reduction in size and condensation of nucleus and cytoplasm. The germ cells lack flagellum and aerosome. The sperms leave the germ producing part of the testis with roundish shape, the invaginations — now pinched off the cell membrane — are to be seen as peripherally located vesicles. The chromatin is condensed, a nuclear envelope is absent. Mitochondria, a Golgi apparatus and ribosomes are reduced.In the receptaculum seminis the sperms are of irregular shape, they bear finger-shaped processes. Below the cell membrane numerous tubules are to be found.ZusammenfassungDie paarigen Hoden vonTetranychus urticae sind wie die anderer prostigmater Milben in einen Keimteil und einen Drüsenteil, der ein weites Lumen (Hodenlumen) enthält, gegliedert. Der Drüsenteil ist schlauchförmig und geht in eine anfangs paarige, dann unpaarige Vesicula seminalis über. DerTetranychus- Penis besteht aus zwei verschiedenen Teilen: einer Ausstülpung der Körperwand, die vom Ductus ejaculatorius durchzogen wird, und einer ventral davon gelegenen kutikularen Einstülpung, an deren proximalem Ende Penisprotraktoren ansetzen.Eine Beschreibung der Feinstruktur der einzelnen Elemente des männlichen Genitaltraktes sowie des Receptaculum seminis des Weibchens wird gegeben.Der Keimteil des Hodens wird aufgebaut von einer vielkernigen somatischen Zelle, die die Keimzellen umgibt. Die Spermiocytogenese ist durch folgende Vorgänge gekennzeichnet: Einfaltung der Zellmembran, Degeneration von Zellorganellen, Größenabnahme und Kondensation von Kern und Cytoplasma. Kinocilie und Akrosomkomplex werden nicht ausgebildet. Die Spermien verlassen den Keimteil als kugelige Gebilde, die abgeschnürten Einstülpungen liegen als periphere Vesikel unter der Zellmembran. Das Chromatin ist kugelförmig zusammengeballt, eine Kernhülle ist nicht vorhanden. Mitochondrien, Golgi-Apparat und Ribosomen sind verschwunden.Im Receptaculum seminis bekommen die Spermien eine unregelmäßige Gestalt mit fingerförmigen Ausläufern. Unter der Zellmembran und parallel zu ihr liegen zahlreiche Tubuli.

The fine structure of the stomochord of the enteropneusts Harrimania kupfferi and Ptychodera flava.

SummaryThe stomochord of Harrimania kupfferi and Ptychodera flava. a tubular structure which extends from the oral cavity into the presoma, consists of two cell types:a)epithelial cells interconnected by desmosomes, which bear at their apical pole a brush-border and cilia. The largest part of these cells is occupied by a voluminous vacuole;b)mucus cells. In addition, at the base of the epithelium numerous nerve fibres occur, which are characterized by electron dense granules of about 1,500 Å diameter. The whole stomochord is surrounded by a basement lamina and connective tissue fibres.The question of homology between stomochord and notochord is discussed.ZusammenfassungDas Stomochord von Harrimania kupfferi und Ptychodera flava, eine Ausbuchtung des Darmkanals der Enteropneusten, welche in das Präsoma hineinragt, besteht aus zwei Zelltypen:a)Epithelzellen, die durch Desmosomen verbunden sind und große Vakuolen besitzen; ihr distaler Zellsaum ist mit Mikrovilli und Zilien ausgestattet.b)Schleimzellen. An der Basis des Epithels kommen zahlreiche Nervenfasern vor, die Granula (Durchmesser etwa 1,500 Å) enthalten.Das Stomochord wird von einer Basallamina und Bindegewebsfasern umschlossen.Die Frage der Homologie des Stomochords mit der Chorda dorsalis wird diskutiert.

Fine structure of the sensilla of Peripatopsis moseleyi (Onychophora)

SummaryThree types of sensilla occurring on the lips and on the antennae of Peripatopsis moseleyi have been investigated by scanning and transmission electron microscopy. On the lips sensory spines can be found which contain numerous cilia originating from bipolar receptor cells. They reach the tip of the spine where the cuticle is modified. The perikarya of the sensory cells, a large supporting cell with a complicated surface and a second type of receptor, form a bud-like structure and are surrounded by a layer of collagen fibrils. The second receptor cell bears apical stereocilia as well as a kinocilium which are directed towards the centre of the animal — thus the cell appears to be turned upside down. The sensilla of the antennae are 1) sensory bristles containing two or three kinds of receptor cells, one of which bears an apical cilium and one kind of supportive cell and 2) sensory bulbs located within furrows consisting of receptor cells with branched cilia and two kinds of supportive cells which are covered by a modified thin cuticle. According to the electron microscopical findings the sensory spines on the lips are presumably chemoreceptors. The sensory bristles on the antennae can be regarded as mechanoreceptors and the sensory bulbs as chemoreceptors.

Podocytes in the blood vessel linings of Phoronis muelleri (Phoronida, Tentaculata)

SummaryIn several metasomal blood vessels of Phoronis muelleri myofilament-containing podocytes are the predominant cell-type. In some regions the podocytes can build a labyrinth resembling e.g. the glomerular epithelium of Enteropneusta and the axial organ of Asteroidea.

Epitheliomuscular cells in Lingula unguis (Brachiopoda) and Branchiostoma lanceolatum (Acrania).

SummaryEpitheliomuscular cells largely corresponding to those of cnidarians have been found in the mesenteria of Lingula and in various coelomic channels of Branchiostoma. They are characterized by basal extensions containing thin and thick myofilaments. In Lingula they also bear an apical cilium.

Septate junctions in the cephalic epidermis of turbellarians (Bipalium)

SummaryIn the epidermis of turbellarians septate junctions of the pleated sheet type have been demonstrated in conventional thin sections and freeze fractured preparations. The structure of these junctions entirely agrees with that found in molluscs and arthropods.