Ultrastructure and formation of the hooked setae in Owenia fusiformis delle Chiaje, 1842: implications for annelid phylogeny

1996 ◽  
Vol 74 (12) ◽  
pp. 2143-2153 ◽  
Author(s):  
Karsten Meyer ◽  
Thomas Bartolomaeus
Keyword(s):  
Extracellular Matrix ◽  
Basal Lamina ◽  
Functional Significance ◽  
Follicle Cell ◽  
Sister Group ◽  
Epidermal Cells ◽  
The Body ◽  
Monophyletic Group ◽  
Follicle Cells

Several members of the Annelida bear apically curved or hooked setae that are aligned in a transverse row inside the neuropodial rim. Based on the hypothesis that these specific setae characterize a monophyletic group within the Annelida, the structure and development of the hooked seta in Owenia fusiformis are analysed and compared with data from other annelids with such setae. The neuropodial hooks of O. fusiformis are arranged in multiple transversal rows or setal patches on each side of the body from the fourth setiger onwards. The setae are curved distally and consist of two identical spines lying side by side at the same level. Their tips generally point ventrofrontally. Within each patch, the setae lie inside a setal follicle that consists of a basal chaetoblast, at least one follicle cell, and varying numbers of epidermal cells. Each setal patch is basally surrounded by an extracellular matrix that is continuous with the subepidermal basal lamina. An additional discontinuous extracellular matrix lies between the epidermis and the follicle cells. It is of functional significance for the attachment of the epidermal cells and seems to be related to the special organization of the setal patches, because it is absent in juveniles; they have single neuropodial rows of hooked setae per segment. New setae are formed at the dorsal and caudal edges of each patch, whereas the degeneration of setae is observed at the frontal edge of each patch. Microvilli project from the apex of the chaetoblast into canals within the fully differentiated setae. These canals remain when the microvilli are withdrawn from the seta during formation. Each hook is formed by a single large microvillus. The results of the present paper substantiate the hypothesis of a homology of the hooked setae in the Oweniida and other Annelida. These results and data from the literature support the hypothesis that the Oweniida is the sister-group of a monophylum which consists of the Terebellida, Pogonophora, and Sabellida.

scholarly journals Gap junctions between the oocyte and companion follicle cells in the mammalian ovary.

1976 ◽  
Vol 71 (2) ◽  
pp. 680-686 ◽  
Author(s):  
E Anderson ◽  
D F Albertini
Keyword(s):  
Electron Microscopy ◽  
Gap Junctions ◽  
Functional Significance ◽  
Adult Mouse ◽  
Freeze Fracture ◽  
Follicle Cell ◽  
Neonatal Rat ◽  
Follicle Cells ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron

Tracer and freeze-fracture electron microscopy of the ovaries of neonatal rat and adult mouse, rat, rabbit, and primate have revealed the presence of gap junctions between follicle cells and oocytes. The junctional connections are found at the ends of follicle cell projections which traverse the zona pellucida and terminate upon microvilli and evenly contoured nonmicrovillar regions of the oolemma. Gap junctions are often seen associated with a macula adherens type of junction. The gap junctions occasionally consist of minute ovoid plaques, but nore frequently appear as rectilinear single- or multiple-row aggregates of particles on the P-face or pits on the E-face. The functional significance of follicle cell-oocyte gap junctions is discussed with respect to the regulation of meiosis and luteinization.

Observations on the epidermis of the miracidium and on the formation of the tegument of the sporocyst of Fasciola hepatica

Parasitology ◽  
1970 ◽  
Vol 61 (2) ◽  
pp. 177-190 ◽  
Author(s):  
V. R. Southgate
Keyword(s):  
Plasma Membrane ◽  
Basal Lamina ◽  
Body Wall ◽  
Fasciola Hepatica ◽  
Epidermal Cells ◽  
The Body ◽  
Transitional Epithelium ◽  
Dense Granules ◽  
Outer Covering ◽  
Body Wall Muscles

The relationship between the ciliated epidermal cells and the subepidermal layer of the miracidium of Fasciola hepatica has been described. Non-ciliated ridge-like extensions of the subepidermal layer separate the ciliated epidermal cells from each other. The sunken portions of the subepidermal layer, each containing a nucleus, lie below the outer body wall muscles of the miracidium and open into the ridge by narrow neck-like connexions. Elongate vesicles, which may be a source of stored plasma membrane similar to that which occurs in the transitional epithelium of other animals, fill most of the ridge. In addition, characteristic round electron dense granules are found in the ridge but the majority are found in the sunken portions of the subepidermal layer.The development and origins of the tegument of the sporocyst of F. hepatica have been described at the ultrastructural level. When the miracidium is in the process of penetrating the snail host, large vacuoles appear between the ciliated epidermal cells and the basal lamina which overlies the muscles of the body wall. These vacuoles have the effect of loosening the epidermal cells from the basal lamina of the body wall of the miracidium. Possible mechanisms involved in the formation of such vacuoles are suggested and discussed.During penetration of the snail the ciliated epidermal cells of the miracidium are lost; the ridge, a syncytial layer between the epidermal cells which is connected with the subepidermal layer, spreads over the basal lamina and exposed body wall muscles of the metamorphosing sporocyst to form the new outer covering of the sporocyst.Cytoplasm passes from the subtegumentary layer into the tegument during this stage of the development of the body wall of the sporocyst. Muscular contraction and microtubules may be involved in the outward movements of this cytoplasm. The nuclei of the subtegumentary layer remain below the muscles of the body wall.Twenty-four hours after penetration of the snail the outer plasma membrane of the tegument forms folds, which greatly increase the surface area.Sixty hours after penetration involutions between the folds, which may indicate pinocytosis, are present, and it is suggested that pinocytosis may play a role in food absorption.The fully formed tegument is a syncytial layer containing numerous electron dense granules, vacuoles, mitochondria and lipid droplets.The results on the formation of the tegument of the sporocyst have been discussed with reference to the controversy about the origins and terminology of the outer covering of the Platyhelminths.

scholarly journals Microscopy of crustacean cuticle: formation of a flexible extracellular matrix in moulting sea slaters Ligia pallasii

2018 ◽  
Vol 99 (4) ◽  
pp. 857-865 ◽  
Author(s):  
J. Štrus ◽  
M. Tušek-Žnidarič ◽  
U. Repnik ◽  
A. Blejec ◽  
A. Summers
Keyword(s):  
Extracellular Matrix ◽  
Posterior Part ◽  
Ct Scanning ◽  
Histochemical Staining ◽  
Epidermal Cells ◽  
The Body ◽  
Capacity Change ◽  
Structural And Functional Properties ◽  
Epicuticular Layer ◽  
Mineral Resorption

AbstractStructural and functional properties of exoskeleton in moulting sea slaters Ligia pallasii from the Eastern Pacific coast were investigated with CT scanning and electron microscopy. Ultrastructure of preecdysial and postecdysial cuticular layers was described in premoult, intramoult and postmoult animals. Cuticle is a flexible extracellular matrix connected to the epidermal cells through pore channels. During premoult epicuticle and exocuticle are formed and during intramoult and postmoult endocuticular lamellae are deposited and the cuticle is progressively constructed by thickening and mineralization. Cuticle permeability, flexibility and waterproofing capacity change accordingly. Elaboration of epicuticular scales connected to an extensive network of nanotubules, establish its anti-adhesive and hydrophobic properties. Labelling with gold conjugated WGA lectins on Tokuyashu thawed cryosections exposes differences in chitin content between exocuticle and endocuticle. Histochemical staining of cuticle shows presence of acidic carbohydrates/glycoconjugates and lipoproteins in epicuticular layer. Chitin microfibrils are formed at the microvillar border of epidermal cells with abundant Golgi apparatus and secretory vesicles. Numerous spherules associated with nanotubules were observed in the ecdysial space in intramoult animals. The mineral component of the cuticle as visualized with CT scanning indicates progressive mineral resorption from the posterior to the anterior half of the body in premoult animals, its translocation from the anterior to posterior part during intramoult and its progressive deposition in the posterior and anterior exoskeleton during postmoult. Cuticle of sea slaters is a unique biocomposite and biodynamic material constantly reconstructed during frequent moults, and adapted to specific physical and biotic conditions of the high intertidal rocky zone.

Functional analysis of chondroitin 4 sulfate constituting osseointegration

Impact ◽  
2019 ◽  
Vol 2019 (8) ◽  
pp. 18-20
Author(s):  
Shuhei Tsuchiya
Keyword(s):  
Functional Analysis ◽  
Extracellular Matrix ◽  
Dental Implants ◽  
Maxillofacial Surgery ◽  
The Body ◽  
Oral And Maxillofacial Surgery ◽  
Direct Connection ◽  
Tooth Replacement ◽  
Living Bone ◽  
Natural Tooth

Osseointegration can be defined as a direct connection, both structural and functional, between living bone and the surface of an artificial implant. Indeed, the word comes from the Greek term for 'bone' and 'to make whole'. In dentistry, once dental implants are placed, the body will react with osseointegration, enabling the implants to become a permanent part of the jaw. There are many benefits to this type of implant, compared with traditional tooth replacement options, not least that dental implants mimic the strength and functionality of a natural tooth. Dr Shuhei Tsuchiya is a researcher based in the Division of Oral and Maxillofacial Surgery at Nagoya University, Japan, who is interested in a range of areas, including regenerative medicine and the extracellular matrix. One of his key preoccupations, though, is shedding light on osseointegration. He and his team are working to unravel the mysteries of the mechanism.

scholarly journals Optical Microscopy and the Extracellular Matrix Structure: A Review

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1760
Author(s):  
Joshua J. A. Poole ◽  
Leila B. Mostaço-Guidolin
Keyword(s):  
Extracellular Matrix ◽  
Confocal Microscopy ◽  
Laser Scanning ◽  
Biological Tissues ◽  
The Body ◽  
Stimulated Emission ◽  
Substantial Part ◽  
Fluorescence Lifetime Imaging ◽  
Structured Illumination ◽  
Structured Illumination Microscopy

Biological tissues are not uniquely composed of cells. A substantial part of their volume is extracellular space, which is primarily filled by an intricate network of macromolecules constituting the extracellular matrix (ECM). The ECM serves as the scaffolding for tissues and organs throughout the body, playing an essential role in their structural and functional integrity. Understanding the intimate interaction between the cells and their structural microenvironment is central to our understanding of the factors driving the formation of normal versus remodelled tissue, including the processes involved in chronic fibrotic diseases. The visualization of the ECM is a key factor to track such changes successfully. This review is focused on presenting several optical imaging microscopy modalities used to characterize different ECM components. In this review, we describe and provide examples of applications of a vast gamut of microscopy techniques, such as widefield fluorescence, total internal reflection fluorescence, laser scanning confocal microscopy, multipoint/slit confocal microscopy, two-photon excited fluorescence (TPEF), second and third harmonic generation (SHG, THG), coherent anti-Stokes Raman scattering (CARS), fluorescence lifetime imaging microscopy (FLIM), structured illumination microscopy (SIM), stimulated emission depletion microscopy (STED), ground-state depletion microscopy (GSD), and photoactivated localization microscopy (PALM/fPALM), as well as their main advantages, limitations.

scholarly journals Natural barriers: waterfall transit by small flying animals

2020 ◽  
Vol 7 (8) ◽  
pp. 201185
Author(s):  
Victor M. Ortega-Jimenez ◽  
Eva C. Herbst ◽  
Michelle S. Leung ◽  
Robert Dudley
Keyword(s):  
Complex Dynamics ◽  
Sister Group ◽  
The Body ◽  
Heterogeneous Structure ◽  
Flight Behaviour ◽  
Physical Constraints ◽  
Physical Barriers ◽  
Translational Speed ◽  
Geomorphological Features ◽  
Stroke Amplitude

Waterfalls are conspicuous geomorphological features with heterogeneous structure, complex dynamics and multiphase flows. Swifts, dippers and starlings are well-known to nest behind waterfalls, and have been reported to fly through them. For smaller fliers, by contrast, waterfalls seem to represent impenetrable barriers, but associated physical constraints and the kinematic responses of volant animals during transit are unknown. Here, we describe the flight behaviour of hummingbirds (the sister group to the swifts) and of various insect taxa as they fly through an artificial sheet waterfall. We additionally launched plastic balls at different speeds at the waterfall so as to assess the inertial dependence of sheet penetration. Hummingbirds were able to penetrate the waterfall with reductions in both their translational speed, and stroke amplitude. The body tilted more vertically and exhibited greater rotations in roll, pitch and yaw, along with increases in tail spread and pitch. The much smaller plastic balls and some flies moving at speeds greater than 2.3 m s −1 and 1.6 m s −1 , respectively, also overcame effects of surface tension and water momentum and passed through the waterfall; objects with lower momentum, by contrast, entered the sheet but then fell along with the moving water. Waterfalls can thus represent impenetrable physical barriers for small and slow animal fliers, and may also serve to exclude both predators and parasites from nests of some avian taxa.

A new species of Largocephalosaurus (Diapsida: Saurosphargidae), with implications for the morphological diversity and phylogeny of the group

2013 ◽  
Vol 151 (1) ◽  
pp. 100-120 ◽  
Author(s):  
CHUN LI ◽  
DA-YONG JIANG ◽  
LONG CHENG ◽  
XIAO-CHUN WU ◽  
OLIVIER RIEPPEL
Keyword(s):  
New Species ◽  
Type Species ◽  
Morphological Diversity ◽  
Transverse Process ◽  
Sister Group ◽  
The Body ◽  
Current Evidence ◽  
Diagnostic Features ◽  
Additional Information ◽  
A New Species

AbstractLargocephalosaurus polycarpon Cheng et al. 2012a was erected after the study of the skull and some parts of a skeleton and considered to be an eosauropterygian. Here we describe a new species of the genus, Largocephalosaurus qianensis, based on three specimens. The new species provides many anatomical details which were described only briefly or not at all in the type species, and clearly indicates that Largocephalosaurus is a saurosphargid. It differs from the type species mainly in having three premaxillary teeth, a very short retroarticular process, a large pineal foramen, two sacral vertebrae, and elongated small granular osteoderms mixed with some large ones along the lateral most side of the body. With additional information from the new species, we revise the diagnosis and the phylogenetic relationships of Largocephalosaurus and clarify a set of diagnostic features for the Saurosphargidae Li et al. 2011. Largocephalosaurus is characterized primarily by an oval supratemporal fenestra, an elongate dorsal ‘rib-basket’, a narrow and elongate transverse process of the dorsal vertebrae, and the lack of a complete dorsal carapace of osteoderms. The Saurosphargidae is distinct mainly in having a retracted external naris, a jugal–squamosal contact, a large supratemporal extensively contacting the quadrate shaft, a leaf-like tooth crown with convex labial surface and concave lingual surface, a closed dorsal ‘rib-basket’, many dorsal osteoderms, a large boomerang-like or atypical T-shaped interclavicle. Current evidence suggests that the Saurosphargidae is the sister-group of the Sauropterygia and that Largocephalosaurus is the sister-group of the Saurosphargis–Sinosaurosphargis clade within the family.

Juvenile hormone increases ouabain-binding capacity of microsomal preparations from vitellogenic follicle cells

1983 ◽  
Vol 61 (7) ◽  
pp. 826-831 ◽  
Author(s):  
T. T. Ilenchuk ◽  
K. G. Davey
Keyword(s):  
Juvenile Hormone ◽  
Binding Capacity ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Curvilinear Relationship ◽  
Scatchard Analysis ◽  
Ouabain Binding ◽  
Binding Characteristics ◽  
Brain Microsomes

A comparison has been made of the effects of juvenile hormone (JH) on the binding characteristics for ouabain of microsomes prepared from brain and from cells of the follicular epithelium surrounding previtellogenic or vitellogenic oocytes in Rhodnius. JH has no effect on the binding of ouabain to brain microsomes and decreases the Kd, but does not alter the Bmax for previtellogenic follicle cells. For vitellogenic follicle cells, Scatchard analysis reveals a curvilinear relationship, which is interpreted as indicating that a new population of JH-sensitive ouabain-binding sites develops as the follicle cell enters vitellogenesis. These results are related to earlier data obtained on the effect of JH on ATPase activity, volume changes in isolated follicle cells, and the development of spaces between the cells of the follicular epithelium.

Fine structure of the regressing interdigital membranes during the formation of the digits of the chick embryo leg bud

Development ◽  
1983 ◽  
Vol 78 (1) ◽  
pp. 195-209
Author(s):  
J. M. Hurle ◽  
M. A. Fernandez-Teran
Keyword(s):  
Extracellular Matrix ◽  
Fine Structure ◽  
Chick Embryo ◽  
Basal Lamina ◽  
Ultrastructural Study ◽  
Active Role ◽  
Epithelial Tissue ◽  
Complex Process ◽  
Cell Processes ◽  
Collagenous Material

There is recent evidence showing that in addition to the well-known mesenchymal necrotic mechanism involved in the disappearance of the interdigital membranes, the ectodermal tissue may also play an active role in the formation of the free digits of most vertebrates. Ultrastructural study of the regressing interdigital membrane of the chick leg revealed significant changes at the epitheliomesenchymal interface. Disruptions of the ectodermal basal lamina and an intense deposition of collagenous material were the most conspicuous changes observed in the extracellular matrix. In addition the basal ectodermal cells showed prominent cell processes projected into the mesenchymal core of the membrane, and mesenchymal macrophages appeared to migrate through the epithelial tissue to be detached into the amniotic sac. It is concluded from our results that the elimination of the interdigital membranes is a complex process requiring the interaction of all the tissue components of the membrane.

Functional significance and neural basis of larval lamprey startle behaviour

1987 ◽  
Vol 133 (1) ◽  
pp. 121-135 ◽  
Author(s):  
S. N. Currie ◽  
R. C. Carlsen
Keyword(s):  
Functional Significance ◽  
Action Potentials ◽  
Startle Response ◽  
Müller Cells ◽  
The Body ◽  
Simultaneous Action ◽  
Muller Cells ◽  
Neural Basis ◽  
Lateral Body ◽  
Motor Effects

1. The vibration-evoked startle response mediates rapid withdrawal in burrowed larval lampreys (ammocoetes). Ammocoetes withdraw in response to vibration by contracting pre-existing lateral bends in the trunk and tail, thus pulling their heads deeper into the burrow. 2. The motor effects of an ammocoete startle response are dependent on pre-existing posture. Areas of lateral body curvature contract more and exhibit larger electromyogram (EMG) amplitudes on their inner sides than on their outer sides. 3. Both of the anterior Mth and posterior Mth' (Mauthner) cells and both of the B1 and B2 (bulbar) Muller cells fired action potentials in response to vibration of the otic capsules. Both B3 and B4 Muller cells were inhibited by vibration, while M (mesencephalic) and I1 (isthmic) Muller cells were inhibited by ipsilateral vibration and excited by contralateral vibration. 4. Simultaneous action potentials in both of the anterior Mth cells were appropriate and sufficient for initiating the startle response EMG in a semi-intact preparation. 5. This study demonstrates a Mauthner-initiated startle response which activates musculature on both sides of the body to produce a rapid withdrawal movement and is thus adapted to the eel-like form and burrowed lifestyle of larval lampreys.

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