Tannage quinonique de la capsule ovigère de la Roussette Scyliorhinus canicula (Linné)

1990 ◽  
Vol 68 (12) ◽  
pp. 2553-2563 ◽  
Author(s):  
Marguerite Rusaouën-Innocent
Keyword(s):  
Capsule Wall ◽  
Scyliorhinus Canicula ◽  
Secretion Process ◽  
Nidamental Gland ◽  
Quinone Tanning

Histochemical and histoenzymological investigations performed on sections of the capsule wall have led to the localisation of the substances involved in the process of quinone tanning. Ultrastructural autoradiography and cytochemical and cytoenzymological techniques applied to the nidamental gland have helped to clarify previous histochemical results and to establish a link between gland secretions and the different capsule layers; a hypothesis concerning the capsule secretion process and its hardening is presented.

Changes in macromolecular organization in collagen assemblies during secretion in the nidamental gland and formation of the egg capsule wall in the dogfish Scyliorhinus canicula

1993 ◽  
Vol 341 (1298) ◽  
pp. 419-436 ◽  
Keyword(s):  
Endoplasmic Reticulum ◽  
Liquid Crystalline ◽  
Secretory Granules ◽  
Capsule Wall ◽  
Micellar Phase ◽  
Scyliorhinus Canicula ◽  
Smectic A ◽  
Nidamental Gland ◽  
Collagen Molecules ◽  
Egg Capsule

The thickest layer (L 2 ) of the egg capsule wall of the dogfish, Scyliorhinus Canicula , is constructed largely from highly ordered collagen fibrils (Knight & Hunt 1976). This collagen is stored and secreted by the nidamental gland and passes through an extraordinary series of ordered phases, m any of which have well defined liquid crystalline structure. We have examined the changes in macromolecular packing of the collagen as it moves from the cisternae of the endoplasmic reticulum to secretory granules, is secreted and then formed into the egg capsule wall. Within the endoplasmic reticulum cisternae the collagen appears anisotropic but becomes assembled into a smectic A or lamellar phase in the Golgi cisternae. This phase persists in early secretory granules, where it is found in conjunction with a micellar phase. As these granules mature, the collagen passes through a cholesteric mesophase before adopting a columnar hexagonal arrangement. On merocrine secretion the granules’ contents revert rapidly to the smectic A-lamellar and micellar phases. As it passes along the nidamental gland tubules, the collagen is first converted into a second distinct micellar phase before assembling into the final fibrils that constitute the egg capsule. These phase transitions give powerful insights into the way in which the macromolecular arrangement of collagen molecules can be modulated and are discussed in the context of a range of other related structural transitions in collagens.

Molecular orientations in an extruded collagenous composite, the marginal rib of the egg capsule of the dogfish Scyliorhinus canicula ; a novel lyotropic liquid crystalline arrangement and its origin in the spinnerets

1996 ◽  
Vol 351 (1344) ◽  
pp. 1205-1222 ◽  
Keyword(s):  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scyliorhinus Canicula ◽  
Twisted Nematic ◽  
Nidamental Gland ◽  
Collagen Molecules ◽  
Bright Field Microscopy ◽  
Egg Case ◽  
Diffraction Patterns

The egg case of the dogfish, Scyliorhinus canicula is a composite material largely constructed from collagen fibrils. It is formed as a drawn extrusion from transverse rows of spinnerets within the lining of the nidamental gland. In the L 2 layer, which forms over 90% of the thickness of the marginal rib, each spinneret extrudes a flattened ribbon which runs the length of the rib and measures approximately 150 x 8.5 μm in cross section. The structure of these ribbons and the orientation of collagen molecules and fibrils within them has been investigated in a correlative study using: low angle x-ray diffraction; bright field microscopy of peeled preparations; transmission (TEM) and scanning (SEM) electron microscopy; confocal and quantitative polarizing microscopy. The way in which the molecular orientations are defined within the spinneret has been followed by SEM of fixed material from actively secreting nidamental glands. The extruded ribbon showed a predominantly biaxial fibril orientation in low angle x-ray diffraction patterns recorded with the beam passing horizontally through the marginal rib. This x-ray pattern is derived from a remarkably regular parabolic arrangement of fibrils superficially resembling that seen in biological twisted nematic liquid crystals. However, evidence is presented here that the arrangement in the marginal rib is novel, apparently arising from authentically curved fibres showing a splayed- or bent- rather than twisted-nematic construction. Evidence is also presented that the spinnerets are able to control molecular orientations in a nematic liquid crystal to produce this and the other arrangements seen in the egg case.

Structure and Formation of the Egg Capsule Tendrils in the Dogfish Scyliorhinus canicula

1994 ◽  
Vol 343 (1305) ◽  
pp. 285-302 ◽  
Author(s):  
D. Feng ◽  
D. P. Knight
Keyword(s):  
Three Dimensional ◽  
High Concentration ◽  
Scyliorhinus Canicula ◽  
Extrusion Dies ◽  
Sequence Of Events ◽  
Nidamental Gland ◽  
Transverse Grooves ◽  
Pass Through ◽  
Specialized Region ◽  
Egg Capsule

The tendrils of the egg capsule of the dogfish Scyliorhinus canicula appear to act as damped springs which become entagled with one another, attaching the capsule firmly to the seaweed Halidrys siliquosa. The present paper describes the structure of tendrils and their method of formation in a specialized region of the nidamental gland which we have termed the tendril-forming region (TFR). The tendrils provide a unique system for studying the assembly of a complexly ordered collagenous material. Tendrils show primary twisting and then undergo secondary helical coiling. In cross section they have a lamellated, spiral construction. Each lamella appears to consist of a broad and a narrow lamina. Collagen fibril orientation is approximately longitudinal in the broad lamina and approximately circumferential in the narrow one. Fine, longitudinal fluid-filled canaliculi lie between the lamellae and may act as shock absorbers. Spherical granules containing a high concentration of tyrosine residues are present in large numbers in the outermost lamellae and may have rubber-like properties. The collagen is probably heavily cross-linked and gives the tendril high tensile strength. The tendril appears to be formed from the adhesion of successive lamellae which are wrapped round a central core as the forming tendril undergoes counter-clockwise (left-handed) rotation within the TFR. The latter appears to represent a modification of the structure of the simpler capsule wall-forming region (CWFR). A wave of progressive activation of tubular glands of the TFR travelling anteriorly followed by a wave of deactivation in the opposite direction appears to be responsible for the secretion of first the posterior tendril, then the marginal rib of the egg capsule and finally the anterior tendril. Secreted material passes from glandular tubules through secretory ducts to a series of parallel transverse grooves which act as complex extrusion dies to form the lamellae of the tendril. We have gone some way towards describing how the complex three-dimensional organization of the tendril is produced by these dies. Observations suggested the following sequence of events within the extrusion dies: secreted material becomes uniaxially oriented in the secretory duct and is then passed between ciliated plates we have termed `baffle plates'. These separate the material into an anterior flow containing vertically oriented collagen molecules and a thinner posterior flow containing approximately horizontally oriented ones. These two flows then pass through a transverse groove to become respectively the broad and the narrow lamina of a single lamella of the tendril. The lamellae become pleated within the transverse grooves probably by anisotropic shrinkage. The canaliculi appear to be formed by the partial adhesion of the pleated lamellae as they are wound onto the forming tendril by rotation within the TFR. The mechanism of rotation of the forming thread and its subsequent coiling in the posterior oviduct is discussed.

scholarly journals Corrigendum “Adverse effects of plastic ingestion on the Mediterranean small-spotted catshark (Scyliorhinus canicula)” [Mar. Environ. Res. 155 March 2020 104876]

2021 ◽  
Vol 169 ◽  
pp. 105325
Author(s):  
Annalaura Mancia ◽  
Tatiana Chenet ◽  
Gioacchino Bono ◽  
Michele Luca Geraci ◽  
Carmela Vaccaro ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Scyliorhinus Canicula ◽  
The Mediterranean
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