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At least 667 records · Page 37Linked to original sources
PubMed1982

Immunohistochemical demonstration of a CCK-like peptide in the nervous system of a marine annelid worm, Nereis diversicolor O.F. Müller.

Perikarya and nerve fibers containing a substance immunologically related to CCK-8 were detected in the nervous system of Nereis, a marine annelid worm. The most noteworthy immunostaining was seen in cell bodies, localized at the periphery of the brain, within nuclei 5, 6, 7, 9, 10, 13, 14, 15, 17, 20, 23-24. Immunoreactive fibers were also found in the neuropile without any particular grouping. Numerous other "positive" perikarya occur in the medioventral portion of the ventral nerve cord, and in the ventral and dorsal parts of the suboesophageal ganglion. In addition to the cell bodies in the cerebral external layer, immunoreactive axons were abundantly observed in the connectives between the ganglia. Moreover, our results demonstrate CCK-like staining in neurons showing variations in size and shape, and in affinity for paraldehyde fuchsin. The present results support the hypothesis that this peptide may exert a role as neurotransmitter or neuromodulator in annelids.

Animals↗
PubMed1983

Ultrastructural studies of neuromuscular junctions in visceral and skeletal muscles of the chaetognath Sagitta setosa.

The ultrastructural characteristics of the neuromuscular junctions were studied in oesophageal (visceral) muscle and in four skeletal muscles of the head and trunk in Sagitta. Three types of neuromuscular junctions were encountered. The first is made up of nerve terminals which synapse with the surface of the muscle fiber, in a deep or in a slight depression. The second is characterized by muscle fiber protrusions that cross the connective tissue and form synapses with nerve endings; in this type, numerous post-junctional membrane folds are noted. In the third type, the synaptic cleft is very large (greater than 0.2 micron) and contains bundles of connective fibers. Nerve endings are partially ensheathed in glial cells; they contain mostly clear synaptic vesicles, though some dense-cored vesicles are noted. In many muscle fibers post-junctional membrane thickenings are also observed. All observed neuromuscular junctions resemble chemical synapses. Chaetognaths thus show a great variety of neuromuscular junction ultrastructure as do for instance Arthropods.

Animals↗
PubMed1978

The respiratory epithelium in the lungs of the slow-worm, Anguis fragilis.

The epithelium covering the respiratory portion in the lung of the slow-worm (Anguis fragilis) has been studied by electron microscopy. The epithelium is composed of two different types of pneumonocytes. The type I pneumonocytes are roughly squamous and their cytoplasmic sheets spread over relatively large areas of the septal walls. These cytoplasmic sheets are attenuated in regions where they overlie septal capillaries; they usually have extensive areas of contact with adjacent cells. The type II pneumonocytes are also squamous but are more compact and possess more organelles. Their osmiophilic inclusion bodies are especially conspicuous. Most of their microvilli are concentrated on the surfaces of cytoplasmic "hillocks". Deposits of membranous material are present in the air sacs. The morphological evidence suggests that the type II cells of Anguis secrete surface-active material.

Annelida↗
PubMed1977

Freeze fracture studies on the annelid septate junction.

Freeze-fractured preparations of septate junctions between epidermal cells of annelids (Lumbricus terrestris and Tubifex spec.) have been investigated. In Lumbricus the protoplasmic face (PF) of the plasma membrane is characterized by variously arranged rows of particles. Apically the rows take an undulating course and often are separated by wide distances. In the basal part of the junction the rows run closely together and more or less in parallel. The diameter of the particles measures 80--120 A, the distance between two particles (centre to centre) is 150--250 A. Additionally striking rows of large particles (long diameter 150--200 A). Are to be observed mainly near the basal part of the junction. In Tubifex both faces of the plasma membrane could be studied in detail. The protoplasmic face (PF) contains rows of distinct individual particles (mean diameter 100--150 A, centre to centre distance approx. 250 A) whereas the particles of the extracellular face (EF, mean diameter 200-250 A) usually form continuous strands in which the individual particles seem to fuse. The density of arrangement of the strands varies considerably. Additionally ladder-shaped membrane structures have been observed in plasma membranes of this species.

Animals↗
PubMed1978

A note on the structure of synapses in the ventral nerve cord of the onychophoran Peripatoides leuckarti.

The fine structure of synapses, their distribution and arrangement in the ventral nerve cord of Peripatoides leuckarti (phylum Onychophora) is described. The asymmetric synaptic junctions show a well developed synaptic cleft (300 A) and pre- and subsynaptic electron dense apposition. They frequently show an array of presynaptic projections and a subsynaptic cisterna of endoplasmic reticulum. The onychophoran synapses differ from those of annelids and insects.

Animals↗