Functional states and fine structure of the contractile apparatus of the penis retractor muscle (PRM) of Helix pomatia L.

1975 ◽  
Vol 156 (2) ◽  
Author(s):  
RudolfW. Wabnitz
Keyword(s):  
Fine Structure ◽  
Helix Pomatia ◽  
Retractor Muscle ◽  
Contractile Apparatus ◽  
Functional States

scholarly journals Observations on the breeding habits, shell development, decollation, and reproductive anatomy of Pontophaedusa funiculum (Mousson 1856) (Gastropoda, Pulmonata, Clausiliidae, Phaedusinae)

2008 ◽  
Vol 7 ◽  
pp. 11-14 ◽  
Author(s):  
Barna Páll-Gergely ◽  
László Németh
Keyword(s):  
Fine Structure ◽  
Young Adult ◽  
Mating Behaviour ◽  
Taxonomic Position ◽  
Retractor Muscle ◽  
Face To Face ◽  
The Family ◽  
Genital Structure ◽  
Egg Morphology ◽  
Reproductive Anatomy

The internal and external egg morphology, shell development, decollation process, mating behaviour and reproductive anatomy (genital structure, inner structure of the penis, fine structure of the retractor muscle and the spermatophore) of the clausiliid Pontophaedusa funiculum (Mousson 1856) are described, and illustrated by photographs of the laid eggs, their inner structure, juvenile, young adult and old individuals, as well as a schematic drawing of the mating. P. funiculum is the only known clausiliid species with hard shelled eggs and the only known example of the family Clausiliidae which mates face to face. The taxonomic position within the Phaedusinae subfamily is mentioned.

The lantern of Echinus esculentus (L.) III . The fine structure of the lantern retractor muscle and its innervation

1966 ◽  
Vol 164 (997) ◽  
pp. 651-658 ◽  
Keyword(s):  
Fine Structure ◽  
Muscle Cell ◽  
Single Neuron ◽  
Vascular System ◽  
Thin Sheet ◽  
Retractor Muscle ◽  
Muscle Fibres ◽  
Nerve Fibres ◽  
Pyramid Structures ◽  
Two Populations

The lantern retractor muscles are attached to the calcareous pyramid structures by a diffuse connective tissue into which the proximal ends of the muscle fibres are inserted. The lantern musculature is invested by a compartment of the water vascular system, and the limiting layer is a thin sheet of ciliated cubical epithelium. The muscle fibres are about 8 to 12 μm in diameter and several millimetres in length. They contain many short myofilaments arranged longitudinally in the cell; these are 1 to 2 μm in length and 45 nm in diameter. The muscle cells show much folding of the surfaces, and there is interdigitation of the surfaces of two contiguous cells. The finger-like projections are often bulbous at the end, containing mitochondria and glycogen droplets. The attachment area of the muscles also contains many nerve fibres. These arise at the hyponeural ganglion, and pass in tracts up to the muscles. The fibres fall into two populations, one (85%) of presumed motor fibres being about 0.8 μm in diameter, the minority (15%) reaching only 0.25 μm. Each muscle cell is innervated by a single neuron at the proximal end. The neuromuscular junction is a short dilation of the nerve wrapped in wing-like process of the surface of the muscle cell. In this area the nerve terminal contains small synaptic-type vesicles, and the muscle cell is possessed of many mitochondria.

The Fine Structure of the Mesenteries of the Sea-Anemone Metridium senile

1958 ◽  
Vol s3-99 (48) ◽  
pp. 523-540
Author(s):  
A. V. GRIMSTONE ◽  
R. W. HORNE ◽  
C.F. A. PANTIN ◽  
ELAINE A. ROBSON
Keyword(s):  
Fine Structure ◽  
Epithelial Cell ◽  
Striated Muscle ◽  
Regular Structure ◽  
Retractor Muscle ◽  
Muscle Fibres ◽  
Fibrous Root ◽  
Epithelial Surface ◽  
Metridium Senile ◽  
Mucus Cells

Sections of the retractor and radial face of mesenteries of Metridium senile (L.) fixed with osmic, osmic-phosphotungstic, or formol-phosphotungstic fixatives were examined by electron microscopy. Each muscle-fibre forms the basal part of a musculo-epithelial cell and is in contact through the cell membrane with a differentiated surface layer of the underlying mesogloea. The muscle-fibres bear crests of cytoplasm containing mito-chondria. Each crest is continuous with a cytoplasmic stem which passes through the intercellular space into the epithelial part of the musculo-epithelial cell. The musclefibre consists of densely packed longitudinal filaments 40-80 Å across. The muscle-fibres present a similar appearance over a great range of extension of the muscle. The filaments show no gross periodic structure like that of striated muscle; nor has any fine regular structure like that described in some other ‘plain’ muscle-fibres yet been detected. There is, however, an irregular beading on the filaments at about 240 Å. Though much smaller, the muscle-fibres of the very slowly contracting radial muscle sheet have the same fine structure as those of the very rapidly contracting retractor muscle. The epithelial part of the cell bears a flagellum arising from a cytoplasmic ‘crater’. The flagellum contains vesicles as well as the typical fibrils. It passes continuously into a complex basal corpuscle which continues into a striated fibrous root. Near the epithelial surface there are conspicuous cross-connexions between adjacent cells. Mucus cells and amoebocytes are described. The mesogloeal lattice of Chapman, which permits free extension of the actinian body, is composed of fibres which seem to be built up of tubular fibrils of about 100 Å diameter. The fibrils show well-developed banding at 260 Å. Where fibrils adhere together their banding is congruent. The criteria of correspondence between the electron micrographs and the living structure are discussed, and the value of information from artifacts and varied methods of fixation is noted.

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