bluuebunny/crossref_metadata_2025_split huggingface dataset:
Form and function of the feeding apparatus of Alligator mississippiensis
Authors: Busbey Arthur B. 
Published: February 2005

AbstractThe architecture of the jaw muscles and their tendons of Alligator mississippiensis is described and their function examined by electromyography. Alligator grabs its prey with forward lunges or rapid lateral movements of the head. It does not engage in regular masticatory cycles. Prey is manipulated by inertial movements and the tongue does not appear to play any role in transport. The Mm. adductor mandibulae externus, adductor mandibulae posterior, and pterygoideus activate bilaterally and simultaneously during rapid closing or crushing. The M. pterygoideus does not act during prey holding whereas the Mm. adductor mandibulae externus, adductor mandibulae posterior continue to be active. The Mm. depressor mandibulae and intramandibularis are variably active during both jaw opening and closing.
Post‐hatching growth of the kidney in the chukar (Aves: Phasianidae)
Authors: Goldstein David L. 
Published: February 2005

AbstractThe post‐hatching growth of the kidney of the chukar partridge, Alectoris chukar, was studied in birds aged 5, 24, 56, and 140 days. As body mass increased from 24 gm (5 d) to 479 gm (140 d), kidney mass increased from 0.16 to 1.6 gm. The number of nephrons in the kidney increased through age 56 d, but did not change thereafter. This increase was primarily a function of increasing development of the cortical regions; more than 90% of reptilian‐type nephrons developed after hatching. The full complement of medullary cones was present at hatching. However, the lengths of the medullary cones and the number of loops of Henle of mammalian‐type nephrons contained in each medullary cone increased through growth, so that approximately 65% of the mammalian‐type nephrons developed after hatching. The chukar kidney contained 19% mammalian‐type nephrons at age 5 d, but this was reduced to approximately 5% by 24 d, after which the proportions of mammalian‐and reptilian‐type nephrons did not change. This study demonstrates that metanephric kidney growth in birds begins in the deepest regions of the kidney and then extends peripherally but also that mammalian‐type nephrons continue to develop throughout kidney growth, presumably from pre‐existing reptilian‐type nephrons.
Ultrastructural features of the developing eosinophils in bone marrow and spleen of the musk shrew, Suncus murinus
Authors: Ishizeki Kiyoto , Nawa Tokio 
Published: February 2005

AbstractEosinophilopoiesis in the musk shrew, Suncus murinus, a representative of the order Insectivora, was studied by light and electron microscopy. To examine biochemical features of cytoplasmic granules, extraction with proteolytic enzymes was carried out on ultrathin sections of bone marrow. In this species, eosinophils are produced in the same manner in both spleen and bone marrow. Developing eosinophils were distinguished as belonging to four stages, recognized by ultrastructural changes in cytoplasmic organelles as well as the eosinophilic granules during maturation. Granulogenesis began by budding of vacuoles containing flocculent material from the concave face of the Golgi apparatus, in the promyelocyte to myelocyte stage. The matrix of developing granules transformed into a finely granular structure, and the large spherical granules of mature eosinophils were homogeneous without crystalline cores. It was shown by proteolytic enzyme extraction that the proteinaceous cores of mature granules were uniformly removed; there was no evidence that they contained crystalloid inclusions. These results indicate that shrew eosinophils can be regarded as cells that retain a prototype of eosinophil granules, probably like those of ancestral mammals rather than those of higher living Mammalia.
Porosity of eggshells from wild and captive, pen‐reared alligators (Alligator mississippiensis)
Authors: Wink Carole S. , Elsey Ruth M. , Bouvier Marianne 
Published: February 2005

AbstractArtificially incubated fertile eggs from wild alligators have a significantly better hatch rate than those of captive, pen‐reared alligators, possibly due to differences in the morphology of the eggshells. We compared the morphology of eggshells of wild alligators to those of captive alligators living in semi‐natural environmental pens. Lengths and widths of eggs were measured and volume was determined, assuming an ellipsoid shape. Eggs were also evaluated for the quality of the eggshell (the presence or absence of rough deposits). Pieces of shell were cut from unincubated eggs and from eggs incubated for 55 days (just before hatching) and examined by scanning electron microscopy. Open pores on the outer surface of the shells were counted and thickness of the pieces was measured from micrographs. Results indicated that the number of pores on eggshells was lowest in eggs of captive alligators with early embryonic death. The number of pores was intermediate in eggs with early embryonic death from wild alligators, and the number of pores was highest in eggs with full‐term embryos from wild or captive alligators. It is suggested that decreased porosity of eggshells may be associated with early embryonic death, is more prevalent in captive animals, and may, therefore, be related to poor hatch rate among penreared alligators.
Histology and histochemistry of the oviductal sperm storage pockets of the agamid lizard Calotes versicolor
Authors: Kumari T. Ruth Shantha , Sarkar H. B. Devaraj , Shivanandappa T. 
Published: February 2005

AbstractSome reptiles are known to possess sperm storage in the female genital tract. Examination of the oviduct of the lizard Calotes versicolor shows the presence of sperm in storage pockets of the uterovaginal region throughout the reproductive cycle. Histochemical studies indicate that the epithelium of these pockets resembles the local oviductal epithelium and that a considerable amount of activity of steroidogenic and metabolic enzymes exists.
Vascular organization of the head and respiratory organs of the air‐breathing catfish, Heteropneustes fossilis
Authors: Olson K. R. , Munshi J. S. D. , Ghosh T. K. , Ojha J. 
Published: February 2005

AbstractLight and scanning electron microscopy of vascular replicas from the facultative air‐breathing fish Heteropneustes fossilis show modifications in the macrocirculation of the respiratory organs and systemic circulation, whereas, gill microcirculation is similar to that found in typical water‐breathing fish. Three and sometimes four ventral aortae arise directly from the bulbus. The most ventral vessel supplies the first pair of arches. Dorsal to this another aorta supplies the second gill arches, and a third, dorsal to, and larger than the other two, supplies the third and fourth arches and the air sacs. Occasionally a small vessel that may be the remnant of a primitive aortic arch arises from the first ventral aorta and proceeds directly to the mandibular region without perfusing gill tissue. The air sac is perfused by a large‐diameter extension of the afferent branchial artery of the fourth gill arch and its circulation is in parallel with the gill arches. Blood drains from the air sac into the fourth arch epibranchial artery. A number of arteries also provide direct communication between the efferent air sac artery and the dorsal aorta. All four gill arches are well developed and contain respiratory (lamellar) and nonrespiratory (interlamellar and nutrient) networks common to gills of water‐breathing fish. Air sac lamellae are reduced in size. The outer 30% of the air sac lamellar sinusoids are organized into thoroughfare channels; the remaining vasculature, normally embedded in the air sac parenchyma, is discontinuous. A gill‐type interlamellar vasculature is lacking in the air sac circulation. Despite the elaborate development of the ventral aortae, there is little other anatomical evidence to suggest that gill and air sac outflow are separated and that dorsal aortic oxygen tensions are maintained when the gills are in a hypoxic environment. Physiological adjustments to hypoxic water conditions probably include temporal regulation of gill and air sac perfusion to be effective, if indeed they are so.
The urohyal: Development and homology within osteichthyans
Authors: Arratia Gloria , Schultze Hans‐Peter 
Published: February 2005

AbstractThe formation of the unpaired structure ventral to the basibranchial region, the so‐called urohyal, differs within osteichthyans. A cartilaginous preformed, unpaired “urohyal” is present in sarcopterygians. A three‐tendon ossification is present in Polypterus. An “urohyal” or urohyal is absent in both Amia and Lepisosteus. The urohyal formed as an unpaired ossification of the tendon of the sternohyoideus muscle is a feature of teleosts. A new structure, the parurohyal, arises as a double ossification of the tendon of the sternohyoideus muscle in siluroids; during ontogeny an anterodorsal crest or cup‐like structure derives from the anterior basibranchial region and the tendon bone; therefore, the parurohyal is compound in origin. Judging from their formation and their distribution within osteichthyans the cartilaginous preformed “urohyal” and the teleostean urohyal are nonhomologous, whereas the urohyal and parurohyal are homologous. The urohyal is connected by ligaments with the ventral hypohyals in most teleosts, whereas it articulates with the ventral hypohyals in teleosts such as Anguilla and Chanos. The parurohyal is a synapomorphy of siluroids. The parurohyal in siluroids is articulated with both ventral and dorsal hypohyals, and with the basibranchial region in catfishes such as diplomystids and ictalurids, whereas it articulates only with the ventral hypohyals in other catfishes such as trichomycterines. The passage of the hypobranchial artery through the hypobranchial foramen of the parurohyal is a unique feature of siluroids, like the absence of the basihyal bone.An ossified dorsal hypohyal appears late in ontogeny in Amia, as do tooth plates related to the medial side of the hyoid arch and branchiostegal rays in Amia, and tooth plates on the hyoid arch and branchiostegal rays in Elops (unique features within extant teleosts). Two ossified hypohyals, a synapomorphy of teleosts, are present early in ontogeny.There is intraspecific variation in the onset of ossification of the bones of the head, but the sequence of ossification between bones in a defined structural system is conserved (e.g., branchiostegal rays ossify first, then bones of the hyoid arch).
An ultrastructural study of the spleen of the ranid frog Rana perezi
Authors: Alvarez Rafael 
Published: February 2005

AbstractThe spleen of Rana perezi is encapsulated by connective tissue and shows by light microscopy two areas with no obvious border: the white pulp and the red pulp. The white pulp–lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp displays two different portions. The predominant region consists of reticular cells, lymphocytes, a variety of other leucocytes, and cells undergoing division. This area possibly performs a haemopoietic function. The smaller portion of the red pulp is characterized by reticular–phagocytic cells and may be haemocaretic in its function. Macrophages and pigmented cells occur in both white and red pulp. The organization of the spleen of R. perezi can be considered as a transitional or intermediate state between the primitive condition seen in certain fishes and amphibians and the more complex organ of ammiotes.
Minute protrusions of the cuticle: Fine surface structures of the tunic in ascidians
Authors: Hirose Euichi , Saito Yasunori , Watanabe Hiroshi , Hashimoto Koichiro 
Published: February 2005

AbstractThe fine structure of the cuticular surface of the tunic was studied by scanning and transmission electron microscopy in 25 species belonging to 9 families of ascidians. The cuticular surface is ornamented with numerous minute protrusions in some species, but not in others. The minute protrusions are usually papillate in shape, and less than ∼0.05 μm high (in some species of the families Polyclinidae and Polycitoridae), or ∼0.1 μm high (in all species of Botryllidae, all colonial species of Styelidae and one solitary species of Pyuridae). In Clavelina miniata (Polycitoridae), the tunic is provided with parallel ridges on the surface of which papillate protrusions are distributed. The minute protrusions of Halocynthia roretzi (Pyuridae) are irregularly shaped, giving an appearance of paving stones. No protrusions are found in the families Didemnidae, Cionidae, Perophoridae, and Ascidiidae, and in one solitary species of Styelidae. At least in some colonial species, the density of the minute protrusions is lower at the edge of the colony than elsewhere. It is very probable that minute protrusions are found shortly after the secretion of tunic, growing larger both in size and in number as the tunic becomes older.
Structure of the kidney in the crab‐eating frog, Rana cancrivora
Authors: Uchiyama Minoru , Murakami Toshiki , Wakasugi Chikashi , Yoshizawa Hideki 
Published: February 2005

AbstractThe structure of the nephron in the ranid frog, Rana cancrivora, was studied by light and electron microscopy. This frog is the only amphibian species to live in mangrove swamps of very high salinity. The nephron consists of the following parts: renal corpuscle, ciliated neck segment, proximal tubule, ciliated intermediate segment, distal tubule, connecting tubule, and collecting duct. The distal tubule is located in the ventromedial region of the kidney, and the other tubules are situated in the dorsolateral region. Renal corpuscles are found between the two regions. Some renal corpuscles have a wide Bowman's space because of the small glomerulus within them. The proximal tubules are composed of columnar cells with a dense luminal brush border of long microvilli and numerous apical vesicles and vacuoles. The initial part of the distal tubule consists of heavily interdigitated cells, characterized by a very regular palisade arrangement of mitochondria. In the terminal part of the distal tubule, shorter mitochondria of the infolding cells are situated irregularly around the nucleus. The connecting tubule consists of principal cells and canaliculus cells. The collecting duct consists of columnar or cuboidal cells; cytoplasmic organelles are relatively sparse. The canaliculus cells are intercalated between principal cells from the terminal distal tubule to the proximal part of the collecting duct. Our findings indicate that the kidney of R. cancrivora is structurally similar to kidneys of other amphibians. These findings are discussed with regard to probable correlations between ultrastructure and function in R. cancrivora.
An ultrastructural analysis of the dispersed cell phase during development of the annual fish, Cynolebias
Authors: Carter C. A. , Wourms J. P. 
Published: February 2005

AbstractCell ultrastructure was investigated during the dispersion phase of development in the annual fish Cynolebias. Three cellular populations encompass the yolk mass during dispersion, namely, 1) the yolk syncytial layer (YSL) or periblast, which lies directly over the surface of the yolk; 2) the deep blastomeres of the blastoderm, which engage in morphogenetic movements on the surface of the YSL and beneath the enveloping layer prior to forming the future embryo; and 3) the enveloping layer (EVL) of the blastoderm, which is a cohesive epithelium that forms the outermost cell layer of the blastoderm. Deep blastomeres contain numerous mitochondria and scattered glycogen rosettes that appear to function in the utilization of energy reserves. These cells also possess surface extensions such as filopodia and ruffles. Numerous microfilaments running parallel to the plasma membrane occur in cell extensions and in the cortical cytoplasm of neighboring blastomeres. In bleb‐like extensions such as ruffles, microfilamentous stress fibers run parallel to the plane of the plasma membrane and prevent cellular organelles from entering the hyaline cap of the ruffle. Deep blastomeres also have basal projections that contain glycogen as well as pits in the basal membrane. Blastomeres move about using the YSL as a substrate. The YSL possesses specializations for nutrient uptake, storage, and transport such as numerous multivesicular bodies and large amounts of glycogen. Glycogen, in the rosette form, occurs in extraordinary amounts, virtually occluding the cytoplasm. Glycogen reserves are postulated to serve as an energy source during diapause. Glycogen is sometimes contained within villous projections that extend from the apical surface of the YSL. This configuration suggests the possibility of glycogen transport to the overlying deep blastomeres. Specializations of the EVL include apical tight junctions and basal lateral zonulae adherentes that interdigitate with those of adjacent EVL cells. The EVL serves as an impermeable membrane that protects the developing egg from the vicissitudes of its environment.
Ultrastructure of the maxillary gland of Asellus aquaticus (crustacea, isopoda)
Authors: Walter Uwe , Wägele Johann Wolfgang 
Published: February 2005

AbstractAsellus aquaticus is a freshwater isopod with an unusually long excretory duct of the maxillary gland. The ultrastructure of this gland is described in detail for the first time. Only one comparable description of an isopod excretory gland has been published until now (for a marine species). The gland is composed of an end sac (coelomosac) with podocytes which allow passive ultrafiltration by haemolymph pressure. The podocytes resorb material (probably proteins) from the primary urine. The opening to the excretory duct is controlled by a valve, which consists of muscular sphincter cells and larger valve cells; the latter protrude into the duct. The ultrastructure of cells in different regions of the excretory duct and of the terminal duct is described and correlated with the possible function of the organ.
Fine structural observations on the process of spermiation in the holocephalan fish Hydrolagus colliei
Authors: Stanley Hugh P. 
Published: February 2005

AbstractThe process of spermiation in the ratfish Hydrolagus colliei is described and compared with that in mammals and amphibians. Spermiation in this species involves prior fluid space expansion both within the apical parts of the Sertoli cytoplasm and in the spaces between Sertoli cells and spermatids. The apical ends of Sertoli cells fragment, including the parts immediately around the spermatid acrosomes. Intercellular material between the spermatid tips and the Sertoli cells dissolves. Concurrently an opening from the seminiferous follicle into the efferent ductule is made by means of changes in cell shape and separation of Sertoli cells and efferent ductule cells that adhere to each other up to the time of sperm release.
Changes in lectin‐binding pattern in the digestive tract of Xenopus laevis during metamorphosis. I. Gastric region
Authors: Ishizuya‐Oka Atsuko , Shimozawa Atsumi 
Published: February 2005

AbstractThe distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin‐biotinperoxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA‐I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA‐I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA.‐I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA‐I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA‐I, SBA, and WGA; and for Con A, RCA ‐I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly idpntifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA‐I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.
The origin, development, and degeneration of the pronephros in Caretta caretta
Authors: Collins Patricia 
Published: February 2005

AbstractAn SEM and TEM study revealed details of the development of the pronephros of Caretta caretta. The pronephros develops and degenerates over 13 days from day 7 to day 20 in embryos incubated at 33°C. Podocytes, with primary branches, secondary branches, and pedicles, on a basal lamina, can be seen from day 11, as can ciliated pronephric tubule ostia opening into the coelom. At this stage the embryo has four pharyngeal arches with unfused mandibular processes, and small fore‐limb buds each with an apical ectodermal ridge. Maturation of the pronephros occurs between days 15 and 17. Degeneration begins around day 18 and is advanced by day 20 when the embryo has a fully developed face, fore‐limbs with digits, and the carapace and plastron have formed.
Endocrine cells and brush cells at the bronchiolo‐alveolar junctions of neonatal syrian hamster lungs
Authors: Ito Takaaki , Kanisawa Masayoshi 
Published: February 2005

AbstractEndocrine cells and brush cells at the bronchiolo‐alveolar junctions of the lung of neonatal hamsters were studied by transmission electron microscopy. On both sides of the junctions (bronchiolar and alveolar), clusters of endocrine cells occur as neuroepithelial bodies (NEB). A few solitary endocrine cells are also present at the alveolar sides of the junctions. Some endocrine cells reach from the basement membrane to the air space but the area of apical cell membrane exposed to the airway is small as the cells are largely covered by Clara cells in the bronchioles and by thin attenuations of alveolar type 1 cells in the alveoli. Some Clara cells around NEB contain cytoplasmic lamellar bodies, similar to those characteristically associated with alveolar type 2 cells. A few brush cells are also seen at both sides of the junctions. Long wide microvilli with filamentous cores extend from the apices of the brush cells. Endoplasmic reticulum and Golgi apparatus are moderately developed. Well‐developed bundles of intermediate filaments course throughout the cytoplasm of some of the brush cells. The functions of endocrine cells and brush cells are unknown. However, the presence of these cells at the bronchiolo‐alveolar junctions of neonatal hamster lungs suggests a role in regulation of respiratory function.