bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of sensory receptors in the flexor carpi radialis muscle of the cat
Authors: Richmond Frances J. R. , Stuart Douglas G. 
Published: February 2005

AbstractThe structures and distribution of encapsulated muscle receptors were examined in serial transverse sections of flexor carpi radialis in the adult cat. Four types of receptors (muscle spindles, Golgi tendon organs, paciniform, and Pacinian corpuscles) were identified. Their structures resembled those encountered in other limb muscles. Pacinian corpuscles were rare and occurred only in the external fascial coat of the muscle near its origin. The other three receptor types were distributed in an uneven but consistent pattern throughout the muscle. As noted previously (Gonyea and Ericson, '77), spindles were largely confined to a deep muscle region comprising less than 20% of the muscle volume, located directly between the long tendon of origin and the tendon of insertion. This region contains the largest proportion of type SO muscle fibers (Gonyea and Ericson, '77). Tendon organs and paciniform corpuscles were concentrated along the tendons that lined the spindle‐rich muscle region. This region appeared to be composed of extrafusal fibers that were shorter and of more oblique pinnation than those in other regions. The localization of muscle receptors to the “oxidativex” core of the muscle in its direct line of pull may have functional implications for afferent input to the spinal cord which are discussed. In addition, the possibility is raised that there are more paciniform corpuscles in flexor carpi radialis (and possibly other muscles) than previously thought.
Effects of Germanium (Ge) on the silica spicules of the marine sponge Suberites domuncula: Transformation of spicule type
Authors: Simpson Tracy L. , Gil Maryvonne , Connes Robert , Diaz Jean‐Pierre , Paris Jean 
Published: February 2005

AbstractGermanium (Ge), in the form of germanic acid, at a Ge/Si molar ratio of 1.0 inhibits gemmule development and silica deposition in the marine demosponge Suberites domuncula. Lower Ge/Si ratios inhibit the growth in length of the silica spicules (tylostyles) producing short structures, but with relatively normal morphology and close to normal width; spherical protuberances occasionally occur on these spicules. A few of the short spicules possess completely round rather than pointed tips. Many of the latter develop when Ge is added (pulsed) to growing animals, thus inducing a change in spicule type. These results indicate that the growth in length of the axial filament is more sensitive to Ge inhibition than is silica deposition and that pointed spicule tips normally develop because the growth of the axial filament at the spicule tip is more rapid than silica deposition. Newly formed spicules initiate silica deposition at the spicule head but the absence of Ge‐induced bulbs as in freshwater spicules (oxeas) leaves open the question of whether there is a silicification center(s) present in Suberites tylostyles. The morphogenesis of freshwater oxeas and of marine tyolstyles appears fundamentally different‐bidirectional growth in the former and unidirectional growth in the latter. X‐ray analysis demonstrate relatively uniform Ge incorporation into the silica spicules with considerable variation from spicule to spicule in the incorporated level. Increased silicic acid concentration induces the formation of siliceous spheres, suggesting that the axial filament becomes prematurely encased in silica.
In situ manifestations of nonself recognition between incrusting sponges
Authors: Van De Vyver Gysèle , Toussaint Dominique , Buscema Marco 
Published: February 2005

AbstractThe present study investigates the morphological aspects of nonself recognition between three incrusting sponge species living in contact.Two types of association have been observed: nonmerging fronts and epizoism. In two of the three combinations studied, Hymeniacidon sanguinea/Halichondria panicea and Halichondria panicea/Ophlitaspongia seriata, nonself contacts consisted of either epizoism or of nonmerging fronts. In contrast, only nonmerging fronts were observed between Hymeniacidon sanguinea and Ophlitaspongia seriata.In the two types of associations, the main phenomenon consists of the isolation of the foreign sponges by a spongin barrier secreted by the partners in the zone of contact. The microscpic structure and the thickness of the barrier vary according to the type of association and the species paired, but they are clearly defined for a given combination.The conditions required for the establishment of epizoism and the existence of a natural xenogeneic tolerance between sponges are discussed.
A freeze‐fracture study of postembryonic differentiation of latissimus dorsi muscles of the chicken
Authors: Zhang Yatian , Shafiq Saiyid A. 
Published: February 2005

AbstractThe differentiation of fiber type characteristics in the anterior (ALD) and posterior (PLD) latissimus dorsi muscles is examined by the freezefracture technique in 1‐, 7‐ and 30‐day‐old chicks. Several characteristics of plasma membrane (caveolae, rectilinear arrays, intramembranous particles) and sarcoplasmic reticulum which show fiber type differences in the adult ALD and PLD muscles are compared in the developmental stages. The caveolar density in the ALD fibers is about 20/μm2 at 1 day increasing to about 37/μm2 at 30 days, whereas in the PLD fibers it remains at about 20/μm2 during this period. The distribution of the caveolae in the two muscles is different from the begining; in the ALD fibers the caveolae are distributed throughout the plasma membrane and in PLD fibers they are patterned into clusters overlying the I band regions. The density of intramembranous particles of 1‐day ALD and PLD plasma membranes appears similar, but by 7 days the particle counts in the sarcolemma of the ALD muscle are about twice as numerous as those in the PLD muscle. The rectilinear arrays are virtually absent in the ALD muscle, whereas in the PLD muscle their density is about 10/μm2 at 1 day and about 20/μm2 at 7 days. Already at 1 day posthatching the SR in ALD and PLD fibers has the adult configuration, i.e., an open irregular network in ALD fibers and periodically arranged tubules with triadic expansions in the PLD fibers. It is concluded that the membrane structure of ALD and PLD muscles is already different at hatching, and at 1 week the differences are identical to those of slow and fast fibers of the adult stage. The membrane changes, therefore, do not support the view that the ALD muscle undergoes a transitional, fast‐type stage in posthatching chicks.
Immunocytochemical study of the hyperglycemic hormone (CHH)‐producing system in the eyestalk of the crayfish Astacus leptodactylus during larval and postlarval development
Authors: Gorgels‐Kallen Janine L. , Meij Johanna T. A. 
Published: February 2005

AbstractImmunocytochemical investigation of the eyestalks of the larval and postlarval stages of the crayfish Astacus letodactylus, using an anti‐Astacus‐CHH serum, shows that immunopositive staining starts in the immediate posthatching larval stage, in neurosecretory cells of the medulla terminalis ganglionic X‐organ (MTGX), in an MTGX‐sinus gland tract, and in part of the axon terminals of the sinus gland. The number of these immunopositive cells increases during postlarval development. Neurosecretory granules belonging to distinct axon terminals of the neurohemal region show immunostaining. The mean diameter of the stained granules increases during postlarval development. The hemolymph glucose concentration in adult crayfish increases after injection of larval eyestalks.
The occurrence of abnormal sperm in the cauda epididymis of Rhinolophus capensis (Mammalia: Chiroptera)
Authors: Bernard R. T. F. 
Published: February 2005

AbstractThe spermatozoa of Rhinolophus capensis are stored in the cauda epididymidis for about 10 months, 4 months prior to copulation and 6 months after copulation. Electron microscopy has shown the occurrence of sperm defects (mitochondrial proliferation, bending and coiling of the tail, and Dag defect) throughout the period of sperm storage. However, these defects are more common during the postcopulation period, when excess spermatozoa are being removed, suggesting that they may be associated with sperm degradation.
Modifications of the fertilized egg surface following the cortical reaction in Limulus polyphemus L. as viewed with the scanning electron microscope
Authors: Barnum Susan R. , Clapper David L. , Brown George G. 
Published: February 2005

AbstractIn the development of the horseshoe crab, Limulus polyphemus, the fertilized egg undergoes a complicated cleavage (Stages 1–3) resulting in blastoderm formation (Stage 4). Stage 1 involves intralecithal cleavage and consists of nine discrete surface modifications (events) which have been briefly described with light microscopy by Brown and Barnum ('83). Since in Stage 1 the cortical reaction (events 1–4) has already been examined with ultrastructural methods, the objectives of the present study were to examine with scanning electron microscopy: (1) the first two of three intermittent granulations (events 5 and 7), and (2) the associated events characterized by smooth surfaces (events 4, 6, and 8). The first granulation occurs 2 1/2 to 3 hours after fertilization (22°C) and lasts approximately 1 1/2 hours. The second granulation appears approximately 5 hours after fertilization and lasts about 3 hours.The dynamic changes that occur during the two granulations involve the transformation of a smooth appearing embryonic surface, liberally coated with microvilli, into a granule‐dominated surface on which microvilli are greatly reduced in number. Also of considerable interest are the numerous projections which begin to appear on the surface near the end of the second granulation (event 7) and dominate the surface of the following smooth step stage (event 8). Hypotheses on the significance of these dynamic changes and surface modifications involve relationships to the cell cycle, possible mechanisms for membrane storage, and secretory function.
Temporal analysis of the role of growth hormone in the initiation and maintenance of limb regeneration in the hypophysectomized newt Notophthalmus viridescens
Authors: Landesman Richard , Hessler Arthur C. 
Published: February 2005

AbstractThis study was designed to investigate and determine for how long, after either hypophysectomy or the third (last) growth hormone injection (to previously hypophysectomized newts), the circulating and now declining titers of endogenous or exogenous hormone remained at a sufficient concentration to permit a morphologically normal forelimb regeneration response in the adult newt Notophthalmus viridescens.To examine the declining levels of endogenous hormone (hormone withdrawal series [HW]), left forelimbs were amputated at specific times following hypophysectomy. Right forelimbs were amputated 5 days prior to hypophysectomy. The declining levels of exogenous hormone hormone replacement series [HR] were examined in newts whose left forelimbs were amputated at specific times following the last of three consecutive alternate‐day growth hormone injections that were initiated 5 days post hypophysectomy. Right forelimbs were amputated immediately following the first hormone injection. All experimental animals were sacrificed when their right forelimbs regenerated to an advanced digitiform regenerate. In both series right forelimbs regenerated normally.In the HW series normal regeneration resulted only when forelimbs were amputated within 48 hours post hypophysectomy, whereas in the HR series normal regeneration occurred in only those newts whose forelimbs were amputated within 12 hours of the last hormone injection. The regeneration response of left forelimbs in both series gradually declined with the time interval between either hypophysectomy or hormone injection and forelimb amputation. As the hormone titer declined, fewer limbs initiated a normal response; they became progressively more hypomorphic and eventually failed to undergo typical regeneration.
Ovarian, oviductal, and placental morphology of the reproductively bimodal lizard, Sceloporus aeneus
Authors: Guillette Louis J. , Jones Richard E. 
Published: February 2005

AbstractSceloporus aeneus exhibits reproductive bimodality. That is, one taxon (Sceloporus aeneus bicanthalis) is viviparous whereas the other (Sceloporus aeneus aeneus) is oviparous. Morphological differences in luteal and oviductal structure were examined. Oviparous and viviparous females have distinct corpora lutea that form immediately after ovulation and remain active until just prior to oviposition or parturition. Luteal activity is correlated positively with follicular atresia. The oviduct of both subspecies is divided into three distinct morphological regions: an anterior infundibulum, a median uterus, and a posterior vagina. The infundibulum and vagina of females exhibiting either parity type are similar, whereas distinct differences in utering morphology are apparent. Primarily, these differences include the loss of uterine glands and a reduction in epithelial cell height in the viviparous form. Moreover, viviparous females possess a simple but well‐developed chorioallantoic placenta and a simple choriovitelline placenta. Chorioallantoic placentation is associated with a significant increase in uterine vascularity, indicating a role in gas and/or water exchange. The evolution of viviparity and placentation are discussed in relation to these observations.
The ultrastructure of the cardiac ganglion of the desert scorpion, Paruroctonus mesaensis (Scorpionida: Vaejovidae)
Authors: Farley Roger D. , Chan Darwin J. 
Published: February 2005

AbstractLight and electron microscopy of the pacemaker ganglion of the scorpion heart indicate that it is about 15 mm long and 50 μm in diameter and extends along the dorsal midline of the heart. The largest cell bodies (30–45 μm in diameter) occur in clusters along the length of the ganglion. The ganglion appears to be innervated with fibers from the subesophageal and first three abdominal ganglia.The cardiac ganglion is surrounded by a neurilemma and a membranous sheath. The latter is apparently derived from connective tissue cells seen outside the ganglion. Nerve fibers other than those in the neuropil areas are usually surrounded by membrane and cytoplasm of glial cells. Often there are several layers of glial membrane, forming a loose myelin. The cardiac nerves to the heart muscle are also surrounded by a neurilemma, and the axons are surrounded by glia. The motor nerves contain lucent vesicles 60–100 nm and opaque granules 120–180 nm in diameter.In the cardiac ganglion, some nerve cell bodies have complex invaginations of glial processes forming a peripheral trophospongium. In the neuropil areas, nerve cell processes are often in close apposition. The septilaminar configuration typical of gap junctions is common, with gap distances of 1–4 nm. In tissues stained with lanthanum phosphate during fixation, we found gaps with unstained connections (1–2 nm diameter) between nerve‐nerve and glial‐nerve cell processes. Annular or double‐membrane vesicles in various stages of formation were also seen in some nerve fibers in ganglia stained with lanthanum phosphate.Nerve endings with electron‐lucent vesicles 40–60 nm in diameter are abundant in the cardiac ganglion, suggesting that these contain the excitatory transmitter of intrinsic neurons of the ganglion. Less abundant are fibers with membrane‐limited opaque granules, circular or oblong in shape and as much as 330 nm in their longest dimension. Also seen were some nerve endings with both vesicles and granules.
The trophotaenial placenta of a viviparous goodeid fish. I. Ultrastructure of the internal ovarian epithelium, the maternal component
Authors: Lombardi Julian , Wourms John P. 
Published: February 2005

AbstractEmbryos of goodeid fishes develop to term within the ovarian lumen, where they undergo considerable increase in weight due to transfer of maternal nutrients across a trophotaenial placenta. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the ovarian lining. The latter was examined by transmission electron microscopy, scanning electron microscopy, and light microscopy in both gravid and non‐gravid ovaries of the viviparous goodeid fish, Ameca splendens. The single median ovary of A. splendens is a hollow structure whose lumen is divided into lateral chambers by a highly folded longitudinal ovarian septum. Germinal tissue occurs within folds of the ovarian lining that extend into each of the two lateral chambers. Matrotrophic embryonic development takes place within ovarian chambers. During gestation, the lining of the ovarian lumen is in direct apposition to body surfaces and trophotaenial epithelia of developing embryos. The ovarian lining consists of a simple cuboidal epithelium, termed the internal ovarian epithelium (IOE), overlying a well‐vascularized bed of connective tissue. Cells of the IOE are apically convex. Well‐developed granular and agranular endoplasmic reticula and numerous large membrane‐bound vesicles with electron‐dense content occupy the apical cytoplasm of IOE cells. Two functional states of the same cell type are distinguished within the IOE. Phase I cells contain few, if any, large apically situated vesicles; Phase II cells contain many. Secretory products of the IOE are presumed to be an important source of nutrients for embryonic development. Structural and functional relationships of the IOE to the trophotaenial epithelium of developing embryos are discussed in relation to maternal‐embryonic nutrient transfer processes.
The digestive system of the lobster, Homarus americanus: I. Connective tissue of the digestive gland
Authors: Factor Jan Robert , Naar Michele 
Published: February 2005

AbstractThe digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), has one continuous network of connective tissue in which the tubules are embedded and suspended and which forms the limiting layer of the organ. Light‐ and electron‐microscopical observations show that the outer connective‐tissue layer investing the entire digestive gland is a typical, fibrous connective tissue, containing hemal sinuses and a variety of cell types embedded in a collagenous matrix. This outer layer is continuous with the connective tissue among the tubules, which lacks a substantial fibrous matrix and lies peripheral to the digestive epithelium of each tubule. It consists of a complex, two‐layered, epithelial basement membrane, an area containing cells, a tunica propria, and hemal sinuses. Several types of cells are present between the basement membrane and the tunica propria: contractile cells form a network of circular and longitudinal processes around each tubule, and several types of granulocytes are found in areas where tubules abut.The previously applied terms “myoepithelium” and “myoendothelium” are inappropriate to describe the tissue among the tubules. Instead, the extraepithelial elements are interpreted as forming an extensive connective tissue supporting the functional units of the digestive gland.
Fine structure of spermatozoa of some labidognath spiders (Filistatidae, Segestriidae, Dysderidae, Oonopidae, Scytodidae, Pholcidae; Araneae; Arachnida) with remarks on spermiogenesis
Authors: Alberti Gerd , Weinmann Claudia 
Published: February 2005

AbstractThe present study reports on the spermiogenesis and spermatozoa of seven labidognath spiders: Filistata insidiatrix (Filistatidae), Segestria senoculata (Segestriidae), Dysdera sp., Harpactea hombergi (Dysderidae), Oonops domesticus (Oonopidae), Scytodes thoracica (Scytodidae), and Pholcus phalangioides (Pholcidae). Filistata insidiatrix is the first cribellate spider whose spermatology is described electron microscopically. A common characteristic of the spermatozoa of the cribellate spider and the remaining species, often referred to as haplogyne spiders, is the coiling process that occurs at the end of spermiogenesis. As a result of coiling, an elongated spermatid is converted into a lens‐shaped structure with the flagellum bearing a 9 × 2 + 3 axoneme becoming incorporated into the cell body. Remarkable differences regarding the main components (shape of nucleus, acrosomal vacuole, implantation fossa, and centriolar complex) probably reflect systematic relationships.The formation of sperm capsules and sperm balls is described for the first time in detail. Sperm capsules occur in Filistata, in which numbers of individual spermatozoa are grouped together by a common secretory envelope established in the distal vas deferens. In contrast, in the sperm balls, two (Harpactea) or four (Segestria, Dysdera, Seytodes) spermatids fuse completely at the end of spermiogenesis. These sperm balls, considered unique in the animal kingdom, are also provided with an envelope. A further peculiarity not reported previously is the occurrence of a large vesicular area in the sperm balls of Dysdera and Harpactea; this area is also found in Oonops, which, however, possesses individual spermatozoa. Components of the spermatozoa such as the acrosomal vacuole, part of the nucleus, and the axoneme protrude into this area and are thus secondarily covered with a membrane.A detailed study of the individual spermatozoa of Pholcus phalangioides completes earlier investigations and stresses the exceptional position of the genus in comparison to that of other spiders.
Muscle system organization in the echinoderms: II. Microscopic anatomy and functional significance of the muscle‐ligament‐skeleton system in the arm of the comatulids (Antedon mediterranea)
Authors: Carnevali M. Daniela Candia , Saita Abele 
Published: February 2005

AbstractComatulids are able to perform quick and complex movements of the arms which are used to swim, creep, walk, and also form a rigid, feeding‐filtration fan. To perform such versatile movements, the arms of these animals are equipped with a classical endoskeletal system, with joints, muscles, ligaments, and a hydroskeleton of three different coelomic channels. Light microscopic study of the detailed anatomical organization of the arm clarifies both the complex relations between the parts involved in the movements and their functional responsibilities. In particular, (1) the ventral muscle bundles show a heterogeneous structure that consists of different and variously arranged populations of fibers, which allows the different flexing movements of the arms (i.e., flexion and maintaining the flexed state); (2) the ligaments (both dorsal and interarticular) consist only of collagen fibrils and, therefore, have a passive function in binding the skeletal pieces together: their possible active engagement in the extending movements of the arms is thus excluded; (3) owing to the absence of other suitable antagonists to the flexor muscles, the only efficient antagonist system seems to be the coelomic cavities, which are well separated from each other and are also provided with muscular valves. They thus function as typical hydraulic systems, which allows the arm to perform both simple extensions and very complex combined movements and to maintain some rigid straight or twisted positions.