bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anatomy of the extrinsic gut musculature of Gammarus minus (Crustacea: Amphipoda)
Authors: Carlton Christopher E. , Schmitz Eugene H. 
Published: February 2005

AbstractInserting on the buccal and esophageal foregut of Gammarus minus are numerous pairs of serially arranged dorsal dilator muscles, a single pair of lateral muscles, and two pairs of posterior muscles. Muscles of the cardiac stomach include three dorsal sets, a single pair associated with the pterocardiac ossicles, and two pairs inserting on the ventral aspect. A single pair of muscles inserts on the lateral aspect of the pyloric stomach. The extrinsic muscles of the foregut originate from exoskeletal apodemes of the cephalothoracic cuticle, sockets of the mandible, and a maxillary bridge that lies just ventral to the cardiac stomach. The extrinsic musculature of the hindgut is restricted to the rectal region and consists of paired dorsal and ventral series in an X‐configuration. A single unpaired muscle inserts on the ventral midline. Extrinsic muscles of the hindgut originate from the integument of the last pleonic segment. The general arrangement of extrinsic gut muscles in G. minus is similar but not identical to that of other amphipods studied. However, the pattern is quite different from that of other malacostracans.
Analysis of the endocardium and cardiac jelly in truncal development in the cardiac lethal mutant axolotl Ambystoma mexicanum
Authors: Lemanski Larry F. , Fitzharris Timothy P. 
Published: February 2005

AbstractRecessive mutant gene c in axolotls results in a failure of the heart to function because of abnormal embryonic induction processes. The myocardium in this mutant lacks organized sarcomeric myofibrils. The present study was undertaken to determine if developmental abnormalities were evident in other areas of the heart besides the myocardium. A detailed comparative survey of the structure of developing normal and mutant hearts, including the endocardium, its cellular derivatives, and the extracellular matrix, known as cardiac jelly, showed that in the mutant there are fewer than the normal number of endocardial cells lining the heart lumen, the number of mesenchyme cells is reduced, and the cardiac jelly area is greatly enlarged in the posterior part of the truncus adjacent to the ventricle.
Electron microscopic investigation relating the occlusal morphology to the underlying enamel structure of molar teeth of the wombat (Vombatus ursinus)
Authors: Ferreira J. M. , Phakey P. P. , Palamara J. , Rachinger W. A. , Orams H. J. 
Published: February 2005

AbstractThis investigation relates the occlusal morphology of the continuously growing molars of common wombats (Vombatus ursinus) to the underlying enamel ultrastructure that was investigated using the techniques of light microscopy, scanning electron microscopy, and transmission electron microscopy. The main feature of the occlusal enamel was a prominent ridge, which followed the contour of the dentine‐enamel junction (DEJ). It was found that the occlusal morphology depended upon the orientation of the dentinal and enamel tissues, variations in prism orientation, Hunter‐Schreger bands (HSB), and presence or absence of cleavage. Cleavage of enamel promoted by sheets of parallel prisms occurred along the face between the DEJ and the ridge, whereas on the face between the ridge and the cementum‐enamel junction (CEJ) cleavage was inhibited by HSB. The slope of the latter face was mainly due to a decrease in wear resistance going from the ridge, where prisms were intercepted transversely, toward the CEJ, where they were intercepted obliquely. Occasionally small surface undulations were observed on the face between the ridge and the CEJ. These undulations were found to correspond to gradually decussating enamel regions. The pronounced cleavage of enamel parallel to the face between the DEJ and the ridge played an important role in conferring on the continuously growing molars a distinct property to develop and maintain a self‐sharpening ridge throughout the life of the tooth.
Morphological comparison of major arteries in the ridgeback prawn, Sicyonia ingentis
Authors: Martin Gary G. , Hose Jo Ellen , Corzine Cathleen J. 
Published: February 2005

AbstractThe structure of the major vessels conducting hemolymph away from the heart of the ridgeback prawn, Sicyonia ingentis, was examined using light and electron microscopy. Three varieties of vessel wall morphology were observed. In most vessels the wall is composed of the following four layers, proceeding from lumen to exterior: (1) thick basal lamina, which selectively stains with Verhoffapos;s Van Giesonapos;s stain for elastin, (2) a continuous layer of cells rich in microtubules, (3) a loose connective tissue layer with highly branched cells widely separated by a fibrillar matrix, which also stains for elastin, and (4) a thin basal lamina covering the outer surface of the vessel. The dorsal abdominal artery shows the second type of vessel wall construction and differs from the previous vessels in the following ways: (1) the inner basal lamina is thinner, (2) a layer of striated muscle replaces the unspecialized endothelial layer, and (3) the connective tissue layer includes two well‐organized bands of elastin‐like material. The hematopoietic vessels that branch off the ophthalmic arteries display the third type of vessel wall morphology. The lumen of the vessel is lined by a very thin basal lamina, which completely encircles the endothelial cells. The rest of the wall is composed of hemocytes, presumably in various stages of maturation, embedded in a matrix of fibroblast‐like cells and collagen fibrils. The morphology of the vessel wall is the same as that previously described for the tubules of the hematopoietic nodules. The functional significance of these different vessel walls is discussed.
Spermiogenesis in the Nile tilapia Oreochromis niloticus with notes on a unique pattern of nuclear chromatin condensation
Authors: Lou Ya‐Huan , Takahashi Hiroya 
Published: February 2005

AbstractSpermiogenesis in the Nile tilapia, Oreochromis niloticus, was observed ultrastructurally. The process of spermatid differentiation can be divided into six distinct stages based mainly on changes in the nucleus of spermatids. During the latter half of the process, nuclear chromatin condenses progressively to form many dense globules, which ultimately adhere tightly to pack the head of mature spermatozoa. During chromatin condensation the nucleus diminishes in size, and part of the nuclear envelope and nucleoplasm forms a vesicular structure that is finally discarded from the cells together with an associated thin layer of cytoplasm. The spermatozoon comprises a roundish head, a relatively small midpiece, and a relatively short flagellum consisting of the usual 9+2 axoneme. No acrosomal structure is developed during spermiogenesis.
Major ocular glands (Harderian gland and lacrimal gland) of the musk shrew (Suncus murinus) with a review on the comparative anatomy and histology of the mammalian lacrimal glands
Authors: Sakai Tatsuo 
Published: February 2005

AbstractThe Harderian gland of the musk shrew Suncus murinus is elongated anteroposteriorly from in front of the eye to behind the ear. The gland is divided into two portions: an anterior portion (A portion) and a posterior portion (P portion). The single secretory duct of the gland emerges from the anterior end of the P portion, receives several secretory ducts of the A portion during the course along it, runs around the ventral aspect of the eyeball, and finally opens into the anterior corner of conjunctival sacs. The two portions of the gland show a fundamentally similar histological structure, having a poorly developed intraglandular duct system and wide tubular alveoli. The quantity of lipid vacuoles and stromal connective tissue in the A portion is greater than in the P portion. The lipid vacuoles in both portions are surrounded by unit membranes, but their contents appear different.The lacrimal gland of the musk shrew is located along the ventral side of the P portion of the Harderian gland. The lacrimal duct emerges from its anterior end, runs around the ventral and anterior aspects of the ear, crosses the A portion of the Harderian gapos; and, and finally opens at the posterior corner of conjunctival sacs. The lobules of the lacrimal gland comprise a branched duct system and terminal acini with two types of secretory cells: (1) acidic cells positive both for the periodic acid‐Schiff reaction (PAS) and for Alcian blue (AB) and (2) neutral cells positive for PAS and negative for AB. Both cell types tend to make separate acini, but when present in the same acinus, the acidic cells occupy relatively peripheral positions in the acinus. Both cell types lack intercellular canaliculi.On the basis of the present study as well as previous descriptions in the literature, the author suggests that the mammalian lacrimal glands can be divided into two sets: (1) a Glandula lacrimalis superior with multiple secretory ducts associated with the upper eyelid and (2) a Glandula lacrimalis inferior with a single secretory duct opening into the lateral corner of the conjunctival sacs. These glands have a fundamentally similar histological structure; but in the rabbit, which possesses both sets of lacrimal glands, they are different. On the other hand, the secretory cells of lacrimal glands generally have no intercellular secretory canaliculi, which are characteristically present between the serous secretory cells of the salivary glands.
Structure of the ovotestis and evidence for heterosynthetic incorporation of yolk precursors in the oocytes of the nudibranch mollusc, Spurilla neapolitana
Authors: Eckelbarger Kevin J. , Blades‐Eckelbarger Pamela I. 
Published: February 2005

AbstractThe ovotestis of Spurilla neapolitana consists of a series of spherical lobes, each of which is composed of radially arranged, sac‐like acini or follicles. The male and female portions of each acinus are separated by ovarian follicle cells and testicular accessory cells. A thick basal lamina serves as a barrier between adjacent acini. The surface of each ovotestis lobe is covered by several layers of myoepithelial cells resting on a connective tissue layer. Developing oocytes are intimately associated with follicle cells except in the last stages of vitellogenesis. Follicle cells are characterized by the presence of extensive arrays of rough endoplasmic reticulum (RER) and Golgi complexes and may play a role in vitellogenesis. An ultrastructural analysis of vitellogenesis suggests that oocytes utilize both auto‐ and heterosynthetic mechanisms of yolk formation. Autosynthetsis is suggested by the activity of the Golgi complex and RER, while heterosynthesis is indicated by high levels of endocytotic activity by the oocyte. Follicle cell development and high endocytotic activity in the oocytes may be a reproductive adaptation to accelerate yolk synthesis, resulting in more rapid egg production.
Comparative study of the choanosome of porifera: II. The keratose sponges
Authors: Vacelet Jean , Boury‐Esnault Nicole , De Vos Louis , Donadey Claude 
Published: February 2005

AbstractThe aquiferous system of representatives of the orders Dictyocer‐atida, Dendroceratida, and Verongida has been studied to note its relevance to the systematics of the groups. The volume of the choanocyte chamber, the size and shape of the choanocytes, the number of choanocytes per chamber, the relative development of the mesohyl, and the features of endopinacocytes are estimated from scanning and transmission electron microscopic observations of representatives of most families of the three orders. Although the Dysideidae have a reticulate skeleton and were classified in the order Dictyoceratida, they are actually closer to the Aplysillidae (Dendroceratida) than to dictyoceratids. The anatomy and cytology of the Halisarcidae differ profoundly from those of these three orders and are clearly more closely related to nonkeratose sponges. Some changes in classification lead to a pattern with highly homogeneous orders that clearly differ in their anatomic and cytologic features, which does not support the hypothesis of a common origin of the “keratose” sponges.
Propulsive action of a snake pushing against a single site: Its combined analysis
Authors: Gasc J. P. , Cattaert D. , Chasserat C. , Clarac F. 
Published: February 2005

AbstractThe simultaneous use of electromyography (EMG), strain gauges, and cinematography show that the capacity of continuous displacement from a single peg is based on the following: sequential activity of the tested muscles from front to rear; activity restricted to the short portion of the body in contact with the peg; alternate action of the muscle longissimus dorsi on the two sides, the transition between one side to the other occurring at the site of contact with the peg; unilateral activity of the muscle supracostalis ventralis responsible for a bulging against the peg; a great stability in the direction of the resultant force, which makes only a small angle with the directio of the motion.
Ultrastructural organization of the accessory olfactory bulb of the lizard Podarcis hispanica
Authors: Llahi S. , García‐Verdugo J. M. 
Published: February 2005

AbstractThe ultrastructural organization of the accessory olfactory bulb (AOB) was studied in a squamate reptile, Podarcis hispanica. Five types of neuronal cell bodies were differentiated by their size, location, and ultrastructure. Dark and light small somata were observed in the glomerular layer and correlated with two possible subpopulations of periglomerular cells. Mitral cells, the biggest neurons in the AOB, were preferentially located in the mitral cell layer, but also observed in plexiform layers, and they could be classified into two different types mainly on the basis of the size of their somata. Finally, a fifth neuronal population, the granule cells, were observed in the deepest layers of the AOB.On the basis of their location and ultrastructure, five different types of synaptic contacts were also observed in the AOB. Vomeronasal nerve terminals made asymmetric synaptic contacts in the glomerular layer. Reciprocal synapses between mitral cell dendrites and granule cell gemmules were identified preferentially in the external plexiform layer, but also in the mitral cell and internal plexiform layers. Terminals forming symmetric synapses on mitral cells were also recognized in the external plexiform layer. In the deepest layers, two types of terminals established asymmetric and symmetric synaptic contacts, respectively, on granule cells.The basic organization of the AOB of lizards appears rather similar to that of the mammalian olfactory bulb, but some notable differences as to their neuronal composition were found.
Neuronal organization of the accessory olfactory bulb of the lizard Podarcis hispanica: Golgi study
Authors: Llahi S. , García‐Verdugo J. M. 
Published: February 2005

AbstractThe neuronal organization of the accessory olfactory bulb (AOB), which receives sensory information from the vomeronasal organ, was described in a squamate reptile (Podarcis hispanica) by means of light microscopy. Using the Golgi‐impregnation method, seven neuronal types could be distinguished:Periglomerular cells constitute a morphologically heterogeneous population of small neurons located between and around the glomeruli.The mitral cells are diffusely distributed in the AOB. Their cell bodies are usually located within the mitral cell layer, but some of them could be also observed in the plexiform layers. Mitral cells were classified into three subgroups on the basis of their sizes and dendritic tree morphologies. Thus, the “outer mitral cells” have the biggest cell bodies, and their distal secondary dendrites are mainly distributed rostrocaudally in the external plexiform layer. The “inner mitral cells” have large cell bodies, and their secondary dendrites are distributed dorsoventrally and are located deeper than those of the other two subgroups. The third type, the “small mitral cells,” is the smallest one among mitral cells in the AOB, and from their cell bodies, only two main dendritic trunks arise.The granule cells are composed of several categories based on their different cell body locations and dendritic tree morphologies. Thus, the “superficial granule cells” are located exclusively in the external plexiform layer and have small dendritic fields. The “middle granule cells” have fusiform cell bodies—situated in the internal plexiform layer—and present a wide dendritic projection area. Finally, the “deep granule cells” are distributed throughout the granule cell layer and include a great variety of dendritic tree morphologies.The distribution and morphological features of all neuronal types constituting the AOB of Podarcis were compared with those reported on other vertebrates. The results suggest that the lamination pattern and neuronal organization of the AOB in lizards are more similar to that of mammals than to that of the remaining vertebrates.
Microscopic study of the pyloric caeca of the starfish Marthasterias glacialis (Echinodermata): Finding of endocrine cells
Authors: Martinez A. , Villaro A. C. , Sesma P. 
Published: February 2005

AbstractThe ultrastructure of five epithelial cellular types is described. (1) Absorptive‐storing cells possess a striated border and accumulate lipids and glycogen. They also contain an apical multivesicular complex and numerous membrane‐bound PAS‐positive granules of unknown significance. (2) Zymogenic cells contain numerous, large secretory granules. These cells also possess microvilli and accumulate lipid droplets. (3) Current‐producing cells contain bundles of thick and thin myofilaments and extend from the basal lamina to the lumen. (4) Mucous cells display the characteristic features of such secretory cells. (5) In addition to these four cellular types, already observed under the light microscope by other authors, endocrine cells have also been identified by both light and electron microscope. They contain variable amounts of secretory granules of diverse sizes and electron densities. Immunocytochemical studies reveal the presence of cells immunoreactive to somatostatin, glucagon, and pancreatic polypeptide. Intraepithelial nerve fibers in contact with endocrine cells are also present. As far as we know, this appears to be the first description of enteroendocrine cells in the phylum Echinodermata.
Obplacental giant cells of the domestic rabbit: Development, morphology, and intermediate filament composition
Authors: Blackburn Daniel G. , Osteen Kevin G. , Winfrey Virginia P. , Hoffman Loren H. 
Published: February 2005

AbstractObplacental giant cells are large (210 m̈m) polyploid cells that appear in the stroma of the pregnant uterus of the rabbit following ovoimplantation. Histological examination of a complete developmental series indicates that obplacental giant cells arise from trophoblastic knobs that have traversed the uterine epithelium during early implantation. During maturation, the cells undergo a massive (approximately 6,000%) increase in volume and penetrate deeply into the uterine stroma and myometrium, where they often become associated with blood vessels and smooth muscle cells. Giant cells at mid‐gestation contain one or two large nuclei with prominent nucleoli and appear to be amitotic. They are rich in Golgi complexes, RER, SER, and cortically distributed cytoplasmic filaments, and contain intracellular canaliculi lined by microvilli. Giant cells vary with respect to the occurrence of lipid droplets, phagocytotic inclusions, lysosomal structures, and electron‐dense granules. Immunocytochemistry demonstrates that the giant cells exhibit intermediate filaments related to cytokeratin and vimentin, but are negative for desmin and for an endothelial cell marker, Factor VIII‐related antigen. The cells are positive for cytokeratin from their inception, but only become vimentin‐positive between Days 12 and 15 of pregnancy, a change seemingly related to their detachment from epithelial tissue to take on an independent existence. Our findings indicate that the giant cells originate from obplacental trophoblast and, at maturity, exhibit cytoskeletal characteristics of isolated epithelial cells, as well as a complement of organelles suggestive of synthetic activity.
Differentiation of the inner ear sensory epithelia of Proteus anguinus (Urodela, amphibia)
Authors: Bulog Boris 
Published: February 2005

AbstractThe stages of differentiation of the inner ear sensory epithelia of the neotenous cave urodele, Proteus anguinus, was studied with light and electron microscopy. Comparative ultrastructural analysis among specimens of different sizes confirms that new sensory cells may be generated throughout life, particularly along the periphery of the saccular macula. The inner ear of Proteus contains at least four types of sensory cells that differ in their apical ciliary part.The lungs and air‐filled buccal cavity may function as transducers of sound pressure in underwater conditions. Sound waves might be transmitted from the buccal cavity to the connected oval window. The very complex orientation of the sensory hair cells of the saccular macula and the large overlying saccular otoconial mass suggest that this macula facilitates orientation of Proteus in its underground aqueous habitat.
Centers of mass and weight distribution in spiders of the family uloboridae
Authors: Opell Brent D. 
Published: February 2005

AbstractIn the Uloboridae, web reduction is accompanied by changes in opisthosomal shape, leg length, and web‐monitoring tactics. These morphological changes make reduced‐web spiders more cryptic and alter their leg leverage and centers of mass. When compared with the orb‐weaver Uloborus glomosus, the irregular, reduced‐web spider, Miagrammopes animotus, invests more mass in its prosoma and first legs. However, the latter species' elongate opisthosoma posteriorly shifts this region's center of mass, causing the relative position of its composite center of mass and the distribution of weight between its first and fourth legs to be similar to that of the orb‐weaver. Like these species, the opisthosomal center of mass of the triangle‐weaver, Hyptiotes cavatus, lies near its midpoint. However, the shorter first legs and rounder, heavier opisthosoma of Hyptiotes posteriorly shift its composite center of mass and distribute more of its weight onto its fourth legs. Consequently, the morphology of M. animotus can be adequately explained by its adaptiveness for web manipulation, balance, and weight distribution and the crypsis that these features confer as an ancillary advantage. In contrast, anatomical changes in H. cavatus are better explained as adaptations for web manipulation and crypsis.
Developmental morphology of the solum nasi in the mouse lemur (Microcebus murinus)
Authors: Lozanoff Scott , Diewert Virginia M. 
Published: February 2005

AbstractThe solum nasi of Microcebus murinus is characterized by the presence of a zona annularis, continuity between the anterior transverse lamina and the paraseptal cartilage, a continuous paraseptal cartilage, a palatine cartilage and a posterior transverse lamina. It lacks a fibula reuniens and possibly a cartilage of the nasopalatine duct as well as a palatine papillary cartilage. The morphology in M. murinus closely resembles that seen in Tupaia and Galago. This affinity results from the retention of primitive traits. However, Galago is reported to lack a zona annularis, thus displaying a specialization not shared with M. murinus. Therefore, the zona annularis provides a useful trait for distinguishing between the ontogenies of M. murinus and Galago.