bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mesodermal metamerism in the teleost, oryzias latipes (the medaka)
Authors: Martindale Mark Q. , Meier Stephen , Jacobson Antone G. 
Published: February 2005

AbstractPrevious studies of the metameric pattern in mesodermal tissues of chick, mouse, turtle, and amphibian embryos have indicated that segmental characteristics exist along the entire length of the embryo. This paper describes this phenomenon in a fish embryo, for some differences in the cranial segmental plan exist between the anamniote and the amniote embryos hitherto studied. Embryos of the cyprinodont, Oryzias latipes, were fixed at various times, then examined by means of stereo scanning electron microscopy. As in other vertebrate embryos, the first indication of mesodermal metamerism in this fish embryo is the occurrence of somitomeres, which are orderly, tandemly arranged units of uncondensed mesenchymal cells in the paraxial mesoderm. As many as ten somitomeres can be observed caudal to the last formed somite to the elongating tail region. In addition, 7 somitomeres are present rostral to the first definitive somite, which is segment number eight. As in other vertebrate embryos examined, somitomeres in Oryzias embryos are circular, bilaminar arrays of paraxial mesoderm that form before any indications of segmentation can be seen with the light microscope. In the trunk region these mesodermal units condense to give rise to definitive somites, but in the head they eventually disperse. Despite a fundamentally different mode of gastrulation and a relatively small number of cells in the newly formed somitomeres, cranial segmentation in Oryzias embryos was found to be more similar in number to the metameric pattern of the embryos of the bird, reptile, and mammal than to the situation found in the two amphibians studied thus far.
A morphological study of the anterior nervous system of the praesoma of Neoechinorhynchus cylindratus (Acanthocephala: Neoechinorhynchidae)
Authors: Gee Randall J. 
Published: February 2005

AbstractThe nerve pathways in the praesoma, based on light microscopy of serial transverse, sagittal, and longitudinal sections stained with Ehrlich's acid hematoxylin are described for the first time for a memeber of Neoechinorhynchus. The route from the cerebral ganglion to the musculature and sense organs of the proboscis and body wall for 11 nerves, five pair and one single, the presence and structure of the Stutzzelle (support cell) and its association with the neck sense organs are described. A comparison with the nervous system in the praesoma of Paulisentis fractus is discussed.
Seasonal changes in the oviduct of the pied myna (Aves: Sturnidae)
Authors: Gupta S. K. , Maiti B. R. 
Published: February 2005

AbstractStudy of the oviduct of the pied myna (Sturnus contra contra) throughout the year reveals that oviducal weight, length, surface epithelial height and glycogen content are low during August to January (nonbreeding phase), partially increase during February to April (prebreeding phase), maximally increase in May (breeding phase) and decrease in June and July (post‐breeding phase). In the nesting cycle, there is greatest growth in all the regions of the oviduct from early nest‐building to the egg‐laying period and this is followed by rapid involution during incubation and nestling periods.Some notable features in the oviduct of the pied myna are described: (1) All five regions of the oviduct (infundibulum, magnum, isthmus, uterus, and vagina) are clearly distinguishable when studied from serial sections of the oviduct even during the nonbreeding phase of the annual ovarian cycle. (2) There is a strong correlation between initiation of tubular gland formation and the onset of nestbuilding activity. (3) The distal part of the magnum is differentiated into a ‘mucous region’ having well developed basal nonciliated cells. (4) A sixth zone can be identified between the magnum and isthmus. Sperm hostlike glands exist at the cranial end of the zone. (5) Several circular epithelial invaginations are evident in the intermucosal folds and their size decreases in centripetal order in the vagina. (6) The pattern and degree of regression are different in various regions of the oviduct.A close synchrony between ovarian and oviducal cycles is indicated in the pied myna (Sturnus contra contra).
Morphology of neurosecretory cells delineated with cobalt applied extracellularly to the cephalic aorta of the insect Rhodnius prolixus
Authors: Chiang R. G. , Davey K. G. 
Published: February 2005

AbstractCobalt applied extracellularly to the cephalic aorta in Rhodnius prolixus filled neurosecretory cells (NSCs) located in the brain, the retrocerebral complex, and the suboesophageal ganglion (SOG). Axons of these cells converged over the corpora cardiaca and corpus allatum and merged into a large tract before travelling posteriorly along the ventral side of the aorta. Cobalt‐filled cells in the posterior margins of the brain and the retrocerebral complex lacked extensive dendritic arborizations, suggesting that their cell bodies and/or axonal processes in the retrocerebral complex are directly involved with integrative processes determining hormone release. Cobalt‐filled cell bodies in the anterior region of the brain were closely associated with the ocellar nerve, and the cobalt‐filled cells in the SOG formed extensive dendritic arborizations in the neuropile, suggesting the involvement of sensory cells in regulation of their electrical activity. The ability to fill NSCs with cobalt applied to the aorta demonstrates that the cephalic aorta of R. prolixus is an important neurohaemal region.
Avian scale development: XI. Immunoelectron microscopic localization of α and β keratins in the scutate scale
Authors: Carver Wayne E. , Sawyer Roger H. 
Published: February 2005

AbstractEpithelial‐mesenchymal interactions play important roles in morphogenesis, histogenesis, and keratinization of the vertebrate integument. In the anterior metatarsal region of the chicken, morphogenesis results in the formation of distinct overlapping scutate scales. Recent studies have shown that the dermis of scutate scales is involved in the expression of the β keratin gene products, which characterize terminal differentiation of the epidermis on the outer scale surface (Sawyer et al.: Dev. Biol. 101:8–18, '84; Shames and Sawyer: Dev. Biol. 116:15–22, '86; Shames and Sawyer: In A.A. Moscona and A. Monroy (eds), R.H. Sawyer (Vol. ed): Current Topics in Developmental Biology. Vol. 22: The Molecular and Developmental Biology of Keratins. New York: Academic Press, pp. 235–253, '87). Since α and β keratins are both found in the scutate scale and are members of two different multigene families, it is important to know the precise location of these distinct keratins within the epidermis. In the present study, we have used protein A‐gold immunoelectron microscopy with antisera made against avian α and β keratins to specifically localize these keratins during development of the scutate scale to better understand the relationship between dermal cues and terminal differentiation. We find that the bundles of 3‐nm filaments, characteristic of tissues known to produce β keratins, react specifically with antiserum which recognizes β keratin polypeptides and are found in the embryonic subperiderm that covers the entire scutate scale and in the stratum intermedium and stratum corneum making up the platelike beta stratum of the outer scale surface. Secondly, we find that 8–10‐nm tonofilaments react specifically with antiserum that recognizes α keratin polypeptides and are located in the germinative basal cells and the lowermost cells of the stratum intermedium of the outer scale surface, as well as in the embryonic alpha stratum, which is lost from the outer surface of the scale at hatching. The α keratins are found throughout the epidermis of the inner surface of the scale and the hinge region. Thus, the present study further supports the hypothesis that the tissue interactions responsible for the formation of the beta stratum of scutate scales do not directly activate the synthesis of β keratins in the germinative cells but influence these cells so that they or their progeny will activate specific β keratin genes at the appropriate time and place.
Morphological changes in the oral (Buccopharyngeal) membrane in urodelan embryos: Development of the mouth opening
Authors: Takahama Hideki , Sasaki Fumie , Watanabe Kyozo 
Published: February 2005

AbstractThe ultrastructure of the oral (buccopharyngeal) membrane in the embryo of the urodelan, Hynobius tokyoensis, was examined by transmission (TEM) and scanning electron microscopy (SEM). The oral membrane consists of the stomodeal ectoderm and foregut endoderm, and is three to five cell layers thick at stage 24. The oral membrane gradually thickens as development proceeds. The stomodeal collar, derived from the ectoderm, is folded inward along the foregut endoderm. Tooth germs are formed partly by cells of the stomodeal collar and partly by mesenchymal cells and calcification takes place before hatching. Secretory granules, which are markers of epithelial differentiation, appear in some cells of the foregut endoderm. Within the oral membrane, the cells of the stomodeal collar become the basal cells, and the endodermal cells of the foregut become the apical cells of the future oral epithelium. Gaps are formed by the epithelial differentiation of the endodermal cells of the foregut in the oral membrane. The gaps connect with each other, with the stomodeum, and with the foregut. As a result of these events, the mouth opens at stage 43, just after hatching.
Reevaluation of the caudal skeleton of some actinopterygian fishes: II. Hiodon, Elops, and Albula
Authors: Schultze Hans‐Peter , Arratia Gloria 
Published: February 2005

AbstractThe vertebral centra of Hiodon, Elops, and Albula are direct perichordal ossifications (autocentra) which enclose the arcocentra as in Amia. An inner ring of ovoid cells forms in late ontogeny from the intervertebral space inside the autocentrum. The chordacentrum is reduced or completely absent in centra of adult Elops, whereas it forms an important portion of the centra in adult Hiodon. The posterior portion of the compound ural centrum 3+4+5 is partially (Hiodon) or fully formed by the chordacentrum (Elops, Albula). The haemal arches and hypurals are fused medially by cartilage or bone trabecles of the arcocentrum with the centra, even though they appear autogenous in lateral view in Elops and Albula. The composition of the caudal skeleton of fossil teleosts and the ontogeny of that of Hiodon, Elops, and Albula corroborate a one‐to‐one relationship of ural centra with these dorsal and ventral elements. The first epural (epural 1) of Elops relates to ural centrum 1, whereas the first epural (epural 2) of Hiodon and Albula relates to ural centrum 2. In Albula, the first ural centrum is formed by ural centrum 2 only. With 4 uroneurals Hiodon has the highest number within recent teleosts. Juvenile specimens of Hiodon have eight, the highest number of hypurals within recent teleosts; this is the primitive condition by comparison with other teleosts and pholidophorids. Reduction of elements in the caudal skeleton is an advanced feature as seen within elopomorphs from Elops to Albula. Such reductions and fusions occur in osteoglossomorphs also, but the lack of epurals and uroneurals separates most osteoglossomorphs (except Hiodon) from all other teleosts.
Ultrastructure of the malpighian tubules of Schistocerca gregaria
Authors: Garrett Margaret A. , Bradley Timothy J. , Meredith Joan E. , Phillips J. E. 
Published: February 2005

AbstractThe ultrastructure of the Malpighian tubules of the adult desert locust, Schistocerca gregaria, is described. Male and female adults possess about 233 tubules, which empty proximally into the midgut‐ileal region of the alimentary canal by way of 12 ampullae. The tubules vary from 10 mm to 23 mm in length. About one third of them are directed anteriorly, attaching distally at the caeca, while the remainder are directed posteriorly, attaching to other tubules, the rectum or large tracheal trunks adjacent to the hindgut. The Malpighian tubules from all locations examined consist of three ultrastructurally distinct regions: proximal, middle, and distal, referring to their position relative to the midgut. All cell types possess ultrastructural features characteristic of ion transporting tissue, i.e., elaboration of the basal and apical membranes and a close association of these membranes with mitochondria. The distal and proximal segments are short (1.5‐1.7 mm) and heavily tracheated, and each is composed of a single, distinct cell type. The middle region is the longest segment of the Malpighian tubule and is composed of two distinct cell types, primary and secondary. Both cell types are binucleate. The more numerous primary cells have large nuclei, contain laminate concretions in membrane‐bound vacuoles, and possess large microvilli that contain mitochondria. The secondary cells are smaller and possess smaller nuclei. The microvilli are reduced and lack mitochondria. Secondary cells do not contain laminate concretions. The possible compartmentalization of ion and fluid transport function based on segmentation in the Malpighian tubules is discussed.
Basement membrane proteoglycans and anionic sites in the fetal rat kidney during late gestation
Authors: Bakala H. , Cornet S. , Cheignon M. , Djaziri R. , Schaeverbeke J. 
Published: February 2005

AbstractProteoglycans were studied in developing rat fetal kidney using cytological and biochemical techniques. These compounds were detected with immunoperoxidase in the nephron basement membranes from the earliest stages of differentiation. In the glomerular basement membrane, immunostaining appeared as both diffuse and granular deposits, as long as this membrane consisted of loose material; however, as soon as a three‐layered membrane had formed, staining was confined to the laminae rarae as regularly arranged granules. The same pattern of staining was observed during differentiation of the basement membrane of the proximal tubule. In Bowman's capsule, immunostaining appeared as granules, which were sparsely distributed in the developing glomerulus and then regularly lined the stacked laminae when differentiation was complete. In all basement membranes, anionic sites (disclosed by polyethyleneimine) were colocated with immunostained granular diposits. Total glycosaminoglycan content gradually increased from the beginning of metanephros development to birth. During this period, the relative proportions of glycosaminoglycans changed: heparan sulfate increased and hyaluronic acid deceased as differentiation proceeded. The possible relationship between morphological observations and biochemical changes in glycosaminoglycan content is discussed.
The anatomy of the middle ear of the tinamiformes (Aves: Tinamidae)
Authors: Saiff Edward 
Published: February 2005

AbstractThe morphology of the middle ear region including the basicranium and quadrate of tinamous is compared among ratites and flying birds belonging to the Procellariiformes, Sphenisciformes, Pelecaniformes, and Ciconiiforms. The middle ears of tinamous and ratites share a number of important characters including absence of a separate foramen for the glossopharyngeal nerve; eustachian tube, carotid artery, and stapedial artery encased in bone; and a metotic process with vascular canals or notches. Outgroup analysis confirms these characters as synapomorphies. These data support the position that the Tinami and Ratiti form a monophyletic assemblage.
Fine structure of larval malpighian tubules and rectal sac in the tick Ornithodoros (Pavlovskyella) erraticus (Ixodoidea: Argasidae)
Authors: El Shoura Samir M. 
Published: February 2005

AbstractThe fine structure of the Malpighian tubules (Mts) and rectal sac (rs) is described in the larval tick Ornithodoros (Pavlovskyella) erraticus before and after feeding up to molting. Mts consist of structurally different pyramidal and cuboidal cells along the entire length of the tubule. In unfed ticks, the two types of cell are characterized by apical microvilli and a few basal membrane infoldings. The abundant pyramidal cells contain glycogen particles, lipid droplets, lysosomelike structures, and rickettsialike microorganisms. After feeding but before molting, pyramidal cells loose glycogen particles and become very dense and dramatically reduced in size. These cells are possibly involved in the formation of guanine crystalloids as an excretory product. In contrast, cuboidal cells, filled with glycogen particles, free ribosomes, and mitochondria in unfed larvae, grow steadily after feeding; their cytoplasm becomes rich in lipid droplets in addition to showing an increase in glycogen particles. Lipid and glycogen could be the source of energy required for water and ion reabsoprtion in which cuboidal cells are probably involved.The paired‐lobe rs consists of one type of cuboidal cells with basal membrane infoldings and a brush‐border microvilli covered by a fuzzy coat of glycocalyx. These cells grow rapidly after feeding; they have functional features indicating extensive, selective reabsorption of essential components from excretory products.
The cleavage pattern in the leech Theromyzon tessulatum (Hirudinea, Glossiphoniidae)
Authors: Sandig Martin , Dohle Wolfgang 
Published: February 2005

AbstractIn order to evaluate the differences in the cleavage patterns of the glossiphoniid leeches Glossiphonia complanata and Theromyzon tessulatum, previously studied by Müller ('32) and Schmidt ('17, '41), the cleavage of Theromyzon tessulatum was reexamined. For the period of the first 29 hours of development embryos were observed, photographed, and serially sectioned for light microscopy at each developmental stage. The exact cell lineage until completion of teloblast formation is reported. Besides some other not previously reported features, we show that the mesoteloblast precursor cell in the glossiphoniid leeches, as probably in most Annelida, is not the cell 3D, but cell 4d formed by an additional division of cell 3D. The results further indicate that all glossiphoniid leeches likely share a common cleavage pattern, and that major differences between Glossiphonia complanata and Theromyzon tessulatum do not exist. A comparison between the cleavage patterns of some Oligochaeta and Hirudinea is made, and plesiomorphic characters in the cleavage of a clitellate ancestor species and their deviations in present day species are discussed.
Localization of serotonin‐like immunoreactivity in the eyestalk of the prawn Palaemon serratus (Crustacea, Decapoda, Natantia)
Authors: Bellon‐Humbert C. , Van Herp F. 
Published: February 2005

AbstractA serotonin‐like substance in the organ of Bellonci in the eyestalks of embryos, larvae, and adults of the prawn Palaemon serratus was visualized by the use of two specific antisera against serotonin (5‐hydroxytryptamine; 5‐HT) in combination with peroxidase‐antiperoxidase (PAP). The organ of Bellonci, characterized by compact onion bodies distally and degenerating onion bodies proximally, was the only site of the serotonin‐like substance in adults, as well as during development in embryos and larvae. Variations in the content of the 5 HT analogue in the adult were detected during the molting cycle. There was more immunoreactivity in specimens fixed at night than in those fixed in daytime. Likewise, colchicine and nialamide injections enhanced the immunoreactivity of the serotonin‐like substance. Extirpations of the medulla externa X organ (MEX), a neurosecretory cell group of the optic ganglion medulla externa, produced the same effect.
Histochemistry of flight muscles in the jamaican fruit bat, Artibeus jamaicensis: Implications for motor control
Authors: Hermanson John W. , Foehring Robert C. 
Published: February 2005

AbstractTwo fast‐twitch fiber types are histochemically identified in the primary flight muscles of Artibeus jamaicensis. These are classified as type IIa and IIb according to an acid‐preincubation staining protocol for myosin ATPase. All fibers in the bat flight muscles exhibit relatively intense staining properties for NADH‐TR, suggesting a high oxidative capacity. The glycolytic potential of all fibers is rather low, as assessed by stains for alpha‐GPD. This two‐type histochemical profile appears to parallel biphasic electromyographic patterns observed in these muscles and leads us to propose that flight muscle histochemistry and activation are mediated by a “two‐gear” neuromuscular control system. In contrast, earlier studies on Tadarida brasiliensis demonstrate the existence of a “one‐gear” neuromuscular control system, exemplified by the presence of one fiber type. These observations are discussed with respect to the natural history and flight styles of several species.
Scanning electron microscopy of changes in epidermal structure occurring during the shedding cycle in squamate reptiles
Authors: Irish Frances J. , Williams Ernest E. , Seling Edward 
Published: February 2005

AbstractPrevious studies of squamate epidermal structure have focused on either histology and ultrastructure or oberhautchen surface texture as revealed by scanning electron microscopy (SEM). Using SEM data drawn from a variety of lizard taxa (primarily iguanids, but also agamids, chamaeleonids, and scincids), as well as amphisbaenians and colubrid snakes, we relate the surfaces encountered in gross dissection of squamate skin to histologically identifiable layers, and characterize their surface structure. Only the oberhautchen bears the repeating pattern of ornamentation noted by previous authors. Because the clear layer is a perfect template of the oberhautchen surface, it is the only layer with which the oberhautchen might be confused. However, the clear layer can be identified by its tendency to curl and crack during preparation. All other surfaces encountered were relatively featureless, except for impressions left by dermal “papillae” associated with mechanoreceptors. Using a method for examining preserved specimens to determine the stage in the shedding cycle, we assess two sources of variation in epidermal surface structure: stage in the shedding cycle and wear. Examination of immature renewal‐phase epidermis suggests that the oberhautchen does not mature synchronously across a single scale or across body regions. Comparing inner‐ and outer‐generation oberhautchen in sheddingphase epidermis, we conclude that changes in surface appearance caused by natural wear fall into two categories: discrete scratches and accumulation of debris. We see no evidence of overall “buffing” on a microscopic level, though surface structure may be obscured by scratches and gouges. Many squamate taxa show a gradient from low relief surface structure on elevated regions such as keels to high relief patterns at scale edges. This gradient is not due to wear; its significance is unknown.