bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Light 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

The 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

The 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

The 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

The 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

Cell 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

Asellus 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

The 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

The 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

An 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

Endocrine 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.
The behavior of pharyngeal outer epithelial cells during regeneration of the planarian Dugesia japonica japonica
Authors: Asai Etsuo
Published: February 2005

The behavior of the nuclei of pharyngeal outer epithelial cells was observed by electron microscopy during regeneration of head fragments of planaria transected at the prepharyngeal region. On the fourth day of regeneration, the surface cells of the pharyngeal rudiment show some evidence of differentiation: septate desmosomes and immature rod‐shaped bodies. These cells then develop many cilia and a few microvilli on their free surfaces, and the electron‐density of their karyoplasm and cytoplasm increases. The basal cytoplasmic processes of the surface cells protrude into the intercellular spaces between underlying cells. Each elongated nucleus goes down into one of these processes. Two types of nuclear descent are observed. The first type occurs when the basal lamina has not yet formed under the epithelial cells. The second type occurs when the basal lamina has already developed under the epithelial cells. Many microtubules are seen running along the long axis of the cells with descending nuclei. Fine fibrous bodies are frequently observed in the descending nuclei of the epithelial cells. Intercellular substances with moderate electron‐density are observed sporadically in the spaces between descending cytoplasmic processes and surrounding cells. Glycogen granules accumulate in large numbers in the basal cytoplasm in the vicinity of the descended nucleus. The mechanism of the descent of the perikarya of the pharyngeal outer epithelial cells is discussed in terms of these results.
Interfiber tension transmission in series‐fibered muscles of the cat hindlimb
Authors: Trotter John A.
Published: February 2005

Several muscles of the cat hindlimb, including biceps femoris and tenuissimus, are composed of short, in‐series muscle fibers with tapered intrafascicular terminations. Tension generation and transmission within such muscles requires that active fibers should be mechanically coupled in series via myomyous junctions, specialized connective tissue attachments, or the endomysium. This report establishes that the tapered fibers of the cat biceps femoris and tenuissimus muscles have insignificant numbers of either myomyous or specialized connective tissue junctions. Tension appears to be transmitted in a distributed manner across the plasmalemma of the tapered (and probably the non‐tapered) portions of the fibers to the connective tissue of the endomysium, which is therefore an essential series elastic element in these muscles. Subplasmalemmal dense plaques were identified and may play a role in transmembrane force transmission. In addition to the endomysium, passive muscle fibers may also serve to transmit tension between active fibers, and therefore should also be considered to be series elastic elements.
Electron microscopic study of the development of amphioxus, Branchiostoma belcheri tsingtauense: The gastrula
Authors: Hirakow R. , Kajita N.
Published: February 2005

The gastrulae of amphioxus were investigated by means of scanning and transmission electron microscopy (SEM and TEM) during 7 arbitrary stages that were seen about 4 to 10 hr after fertilization. Throughout gastrulation, SEM revealed subtle differences in cells of the blastoporal lip. In fractured specimens at early and middle stages, two opposing zones different in shape, size, and connection of the component cells were found: one which consists of columnar smaller cells in close contact in animal region and the other which is composed of round or polygonal larger cells in looser association in vegetal region. The polar body was found unexpectedly on the concave vegetal surface of the early gastrula in about 25% of cases. This might be the result of migration of the polar body. A short cilium that later elongated was recognized on each cell at mid‐gastrula stage. The cilia on the dorsal surface (the neural ectoderm) of the final‐stage gastrula became shorter than those on the epidermal ectoderm. TEM of thin sections demonstrated that the cytoplasmic components of gastrula cells are essentially the same as those of cleavage cells. But, the homogeneous nucleus seen during cleavage changed into a heterogeneous structure in which a nucleolus and dense particles were seen. Until the late stage, regional characteristics of the gastrulae indicating definitively the anterior‐posterior and dorso‐ventral polarity were not detected in the present SEM and TEM study.
Ultrastructure of the agranular cells in the adenohypophysis of the South American lungfish, Lepidosiren paradoxa
Authors: Chiba Akira , Oka Shunya , Honma Yoshiharu , Ishiyama Mikio
Published: February 2005

Light and electron microscopic examination demonstrated two types of non‐endocrine agranular cells, cavity boundary cells and stellate cells, in the adenohypophysis of the South American lungfish, Lepidosiren paradoxa. The cavity boundary cells line the hypophyseal cleft and diverticulum and display few microvilli, occasional cilia, prominent junctional complexes, and many cytoplasmic microfilaments. The stellate cells are scattered in the glandular parenchyma and are devoid of microvilli and cilia. When adjacent, they are connected to one another by desmosomes. Pinocytotic vesicles or caveolae are frequently seen along the plasma membrane of the agranular cells adjoining the endocrine cells or abutting on the basement membrane. Possible roles of the agranular cells, physically and metabolically supportive functions, are discussed on the basis of their ultrastractural features.
Orbital gland structure and secretions in the Atlantic bottlenose dolphin (Tursiops truncatus)
Authors: Tarpley Raymond J. , Ridgway Sam H.
Published: February 2005

Orbital gland structure of the Atlantic bottlenose dolphin, Tursiops truncatus, was examined at the macroscopic, light microscopic, and electron microscopic levels. The gland completely encircles the ocular globe in a belt‐like fashion near the conjunctival fornix but is considerably more developed medially. Duct openings are scattered throughout the fornix and over the surface of the palpebral conjunctiva. Microscopically, the gland has a tubuloalveolar arrangement; alveolar cells contain numerous secretory vesicles which can be interpreted as two structural types by light and electron microscopy. Histochemical staining demonstrates that both types contain glycosaminoglycans. Lipid analysis of the glandular secretion (dolphin tears) shows them to be non‐oily and to contain only negligible amounts of cholesterol, triglycerides, phospholipids, and free fatty acids. The secretion is clear, slippery, and viscoelastic and well‐adapted to protecting the eye and to reducing frictional forces between the eye surface and surrounding seawater.
Fine structure of the spermatophores and their ejaculated forms, sperm reservoirs, of the Japanese common squid, Todarodes pacificus
Authors: Takahama Hideki , Kinoshita Tsutomu , Sato Michio , Sasaki Fumie
Published: February 2005

Spermatophores in a squid, Todarodes pacificus, were observed by light and electron microscopy and were further analyzed by X‐ray microanalysis (XMA) of frozen thin sections. Each spermatophore consists of a sperm mass, a cement body, an ejaculatory apparatus, and some fluid materials, all of which are covered by an outer tunic. The outer tunic consists of about 20 membranous layers, each containing straight, parallel microgrooves. Each layer's microgroove pattern is roughly in an orthogonal arrangement with respect to the next layer's pattern. The sperm mass, which is the only cellular component, consists of a sperm rope which is coiled more than 500 times. Most of the spermatozoa in the rope are arranged regularly and are enveloped in materials which are well‐stained by Alcian blue. The cement body is located between the sperm mass and ejaculatory apparatus and has a hard outer shell with an arrowhead‐like structure, presumably for penetration into the tissue of the female. Calcium and phosphorus are present in the shell of the cement body, which also has an affinity for alizarin red. The ejaculatory apparatus consists of two tubes, designated as the inner tunic and the inner membrane.

After the spermatophoric reaction, a sperm reservoir is formed at the anterior end of the extruded and inverted ejaculatory apparatus. The sperm reservoir, which encases the sperm mass, is composed of the cement body at the anterior end and the inner tunic of the ejaculatory apparatus at the posterior end.
Comparative anatomy and phylogeny of the cloacae of salamanders (Amphibia: Caudata). II. Cryptobranchidae, Hynobiidae, and Sirenidae
Authors: Sever David M.
Published: February 2005

Cloacae were examined from salamanders representing the three families in which fertilization of eggs is known or inferred to occur externally. The cloacae of male and female sirenids are aglandular and lack cilia. Sexual dimorphism in sirenid cloacae occurs only in the extent of epithelial stratification in the cloacal chamber in females (entire chamber) versus males (posterior angle of the vent). Both male and female Cryptobranchus alleganiensis possess ventral glands that secrete an acid mucopolysaccharide and have ciliated cloacal linings. The ventral glands are more numerous and hypertrophied in breeding male than female C. alleganiensis, but in males, ventral glands secrete only onto the surface of the cloacal lips along the anterior three‐fifths of the cloacal orifice, whereas in females, the glands secrete onto the border of the entire cloacal orifice. Except for male Onychodactylus japonicus, male and female hynobiids also possess only ventral glands and have ciliated cloacal linings. Hynobiid ventral glands secrete a glycoprotein. Much variation occurs, however, among these hynobiids in cloacal conformation, extent of epidermis into the cloaca, and anatomy of the ventral gland. Male O. japonicus possess an unciliated cloaca in which three types of cloacal glands occur, each giving unique reactions to tests for carbohydrates and proteins. The glands in male O. japonicus do not seem to be homologous to those found in spermatophore producing salamanders in the Salamandroidea, but this does not negate the possibility that O. japonicus makes spermatophores. Examination of cloacal characters in additional species of hynobiids may be useful in resolving intrafamilial phylogenetic relationships.
Collagen type conservation during metamorphic repatterning of the dermal fibers in salamanders
Authors: Frolich Larry M. , Schmid Thomas M.
Published: February 2005

The orientation of the fibers in the dermis of the tiger salamander, Ambystoma tigrinum, undergoes a dramatic repatterning at metamorphosis. The pre‐metamorphic, larval dermis is a tight layer composed of crossed fibers that wind helically around the trunk. This condition is retained by neotenic adults which do not undergo metamorphosis. In contrast, the metamorphosed adult dermis consists of a superficial, loose network of fibers invested with large multicellular glands—‐the stratum spongiosum—and a deeper tight layer of fibers—the stratum densum. However, unlike the crossed fibers of the pre‐metamorphic dermis, there is no preferred orientation to the fibers in either layer of the post‐metamorphic dermis.

In order to evaluate whether these two distinctly different fiber patterns are constructed from biochemically similar fibers, the collagen types present in the pre‐ and post‐metamorphic dermis were determined using SDS‐polyacrylamide gel electrophoresis. Type I collagen is the predominant collagen of the dermis and the same major collagen types are present for all individuals, whether preor post‐metamorphic. Thus, the major types of collagen that compose the dermal fibers do not change during metamorphic repatterning of the dermis.
Three‐dimensional architecture of identified cerebral neurosecretory cells in an insect
Authors: Westbrook Anne L. , Haire Mary E. , Kier William M. , Bollenbacher Walter E.
Published: February 2005

The organization of identified neurosecretory cell groups in the larval brain of the tobacco hornworm, Manduca sexta, was investigated immunocytologically. Computer‐assisted three‐dimensional reconstruction was used to examine the architecture of the neurosecretory cell groups. The group III lateral neurosecretory cells (L‐NSC III) which produce the prothoracicotropic hormone are located dorsolaterally in the protocerebrum and extend axons medially that decussate to the contralateral lobe prior to exiting the brain through the nervi corporis cardiaci I + II. The group IIa2 medial neurosecretory cells (M‐NSC IIa2) are located anteriorly in the medial dorsal protocerebrum. The axons of these cells also exit the brain via the contralateral nervi corporis cardiaci I + II. However, their axons traverse a different pathway through the brain from that of the L‐NSC III axons. Each of the cell groups possesses elaborate dendrites with terminal varicosities. The dendrites can be classified into specific fields based upon their location and projection pattern within the brain. The dendrites for these two neurosecretory cell groups overlap in specific regions of the protocerebral neuropil. After the axons of these neurosecretory cells exit the brain through the retrocerebral nerve, they innervate the corpus allatum where they arborize to form neurohemal terminals in strikingly different patterns. The L‐NSC III penetrate throughout the glandular structure and the M‐NSC IIa2 terminals are restricted to the external sheath. A third group of cerebral neurosecretory cells, the ventromedial neurons (VM) which stain with the monoclonal antibody to prothoracicotropic hormone in Manduca, are located anteriorly in the medial region of the brain. The axons of these cells do not exit the brain to the retrocerebral complex, but rather pass through the circumesophageal connectives and ventral nerve cord. These neurons appear to be the same VM neurons that produce eclosion hormone. One dendritic field of the L‐NSC III terminates in close apposition to the VM neurons. The distinct morphologies of these neurosecretory cell groups in relation to other cell groups and the distribution of neuropeptides within the neurons suggest that insect neurosecretory cells, like their vertebrate counterparts, may have multiple regulatory roles.
Variation in venous drainage of the pectoral fins of batoids (subclass elasmobranchii: Superorder batoidea)
Authors: Alexander R. L.
Published: February 2005

A contrast radiographic study of pectoral fin venous drainage in rays shows it to be morphologically conservative across the batoids studied. In all species examined, ventral propterygial and mesopterygial veins drain the anterior and posterior lobes of the fin, respectively. Variation in the central connections of these vessels enables the identification of four major patterns of drainage. A fifth pattern consists of additional veins that drain the central region of the fin between the zones drained by the pro‐ and mesopterygial veins. There is a significant, positive association between the numbers of brachial veins present and the dimensions (in numbers of radial cartilages) of the central, basal region of the fin. There is also an association between the types of patterns present and the dimensions of the propterygial and metapterygial basal cartilages.
Testis and epididymis of the indian wall lizard (Hemidactylus flaviviridis): Effects of flutamide on FSH and testosterone influenced spermatogenesis, Leydig Cell, and Epididymis
Authors: Rai Umesh , Haider Shamim
Published: February 2005

To determine the separate spermatogenic actions of FSH and testosterone, adult male lizards Hemidactylus flaviviridis with recrudescent testes were administered the non‐steroidal antiandrogen flutamide either alone or in combination with FSH or testosterone, and the histology and histochemistry of the testes and ductus epididymides were studied. Flutamide‐treated animals displayed a marked hypertrophy of Leydig cells. A few spermatids were also seen in testis of more than half the animals treated with flutamide. Flutamide also produced a significant increase of primary spermatocytes; no spermatids were observed in controls. A significant inhibition of spermatogenesis was noted in lizards treated either with testosterone alone or in combination with flutamide. Ovine FSH treatment caused a significant stimulation of spermatogenesis, as indicated by the increase of primary and secondary spermatocytes and the transformation of secondary spermatocytes into spermatids or, in a few cases, into spermatozoa. A considerable depletion of sudanophilic lipid and moderate Δ5‐3β‐hydroxysteroid dehydrogenase activity was noted in the Leydig cells of FSH‐treated animals indicating enhanced steroidogenesis. Similar results were obtained when lizards were treated with flutamide + FSH. The effects of simultaneous treatment of flutamide with FSH or testosterone on ductus epididymidis revealed that flutamide markedly inhibited the epithelial cell height and lumen diameter with a loss of luminal content when compared to FSH or testosterone‐treated lizards.
The gill arch of the striped bass (Morone saxatilis). IV. Alterations in the ultrastructure of chloride cell apical crypts and chloride efflux following exposure to seawater
Authors: King Judy A. C. , Hossler Fred E.
Published: February 2005

Osmotically induced alterations in the ultrastructure of the apical crypts of chloride cells and changes in chloride efflux were studied in striped bass (Morone saxatilis). Striped bass were divided into three groups: fish adapted to freshwater, fish transferred directly from freshwater to 100% seawater (3% salt, w/v) for 24 hr or less, and fish adapted to 100% seawater for 7 days or more. Transmission electron microscopy studies revealed multicellular complexes of cells in both freshwater‐ and seawater‐adapted fish. Cytoplasmic indigitations between cells in the complex were more numerous in seawateradapted bass. Scanning electron microscopy studies showed that the apical extensions in freshwater fish were uniform in size. Changes in ultrastructure and chloride efflux were observed within 3 hr after transfer to seawater. Initially the apical extensions of chloride cells become longer, more prominent, and branched. After 7 days in seawater some of the apical crypts develop into a deeper “pit” structure, while others remain like those of freshwater fish. An increase in the number of apical crypts is measured by 14 days after transfer. Chloride efflux increases to five times freshwater values after 24 hr and 17 times freshwater values after 7 days in seawater. Mitochondrial density is not significantly different between freshwater and seawater fish (7 or more days). The response of chloride cell apical crypts is not an all‐or‐none phenomenon as observed in other species. Striped bass are able to increase chloride efflux when osmotically stressed with little ultrastructural alteration.
Structure of the adult female reproductive system and oogenetic mode in the sea spider, Endeis nodosa (Pycnogonida; Endeidae)
Authors: Miyazaki Katsumi , Makioka Toshiki
Published: February 2005

As in other pycnogonids, the adult female reproductive system of Endeis nodosa is limited to the trunk and walking legs of the cephalothorax. The U‐shaped trunk ovary extends eight blind branches separately into the corresponding walking legs up to each femoral segment. In both the trunk and pedal region, the ovary lies dorsally above the gut, sandwiched between the dorsal and the ventral layer of the horizontal septum. Oogonia and very young oocytes occur throughout the ovary. They fill the trunk ovary and, in the tubular pedal ovary, are aggregated into several cord‐shaped longitudinally arranged germ zones. More advanced oocytes occur only in the pedal ovary. None lie in the germ zones. but instead they protrude individually from the wall of the pedal ovary into the hemocoel on cellular stalks. Vitellogenesis occurs in the larger stalked oocytes. An oval genital pore with a cuticular lid lies on the ventral surface of the second coxa of each walking leg. The pedal ovarian lumen is directly connected to the genital pore by a short oviduct in the second coxa. The ovarian structure and oogenetic modes in this pycnogonid species show some common characteristics with those of most chelicerates.
Cytology and function of the madreporite systems of the starfish Henricia Sanguinolenta and Asterias Vulgaris
Authors: Ferguson John C. , Walker Charles W.
Published: February 2005

The madreporite regions of two species of starfish were examined by high‐resolution light microscopy and transmission electron microscopy. In both, the madreporite gutter epithelium is predominantly composed of ciliated cells, each bearing a single elongate cilium and numerous microvilli that support and are embedded in cuticle. Fine, contractile pores (10–12 μm) open from the gutters into canals that descend mainly to the underlying ampulla and stone canal. Cells at the pore openings lack cuticle, have rounded, sometimes protruding apices, and bear intermeshing cilia that extend outward through the pores. Below them, the pore canal is lined with irregular, granule‐containing ciliated cells possessing retractable apical head pieces and secretory cells containing clusters of unstainable vesicles. Above the basal lamina here and elsewhere is a well‐developed nerve plexus. Where the pore canals open into the ampulla and connecting axial sinus, the ciliated cells are more cuboidal, vesiculated secretory cells are absent, and free coelomocytes are numerous. The stone canal is lined with tall, densely packed ciliated cells with numerous microvilli and long iuminal extensions. Cells on its central ridge tend to form choanocyte‐like collars. The stone canal appears to be a strong ciliary pump that draws fluid from the axial sinus and madreporite pores. It is likely that the complex form of the madreporite gutters and pore canals provides multiple levels of coordinated defense against the entry of undesirable materials, and probably satisfaction of much of the nutritional needs of the parts from incoming and recirculated fluid.
Ultrastructure of the nephron of the young camel Camelus dromedarius
Authors: Safer A. M. , Abo‐Salem K. S.
Published: February 2005

The present study was undertaken to compare the ultrastructure of the kidney of young camels (Camelus dromedarius) with that of adult kidneys, described previously (Safer et al., '88). Young kidneys are known to produce a urine that is only about half as concentrated as that of adult kidneys (Maloiy, '72; Abo‐Salem, '88). While possessing most of the ultrastructural features of adult kidneys, and of mammalian kidneys in general, young kidneys differ from those of adults in several respects. The basal lamina comprising part of the filtration barrier is approximately one‐fourth as thick as that of the adult kidney. Young kidneys also lack thickened, heterogeneous basal laminae associated with the parietal layer of Bowman's capsule, proximal convoluted tubules, and the thin segments of the loops of Henle in adult kidneys. In addition, the proximal convoluted tubules of young kidneys contain mixtures of lightly stained and darkly stained cells, while those of adult kidneys possess only lightly stained cells. These differences between young and adult kidneys might in part be related to a greater degree of water deprivation experienced by adult animals.
Ultrastructure of sperm development in the plant‐parasitic nematode Xiphinema theresiae
Authors: Kruger Johan C. De W.
Published: February 2005

Spermatogenesis and sperm ultrastructure were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in the longidorid Xiphinema theresiae. All germ cell stages, except spermatogonia, are present in the testes of young adult males. The nonflagellated, slightly elongated sperm displays little intraspecific variation and, although never polarized into a head and tail region, has a remarkably precise form, with a high degree of internal organization. Incipient fingerlike pseudopodia appear in the young spermatid and increase to such an extent that the adult sperm has a conspicuous “woolly” appearance. Microfilament bundles encircle the perinuclear mitochondria in the spermatid, and seem to be closely associated with the evaginated plasma membrane, especially in the spermatozoon. A large nucleus with nuclear envelope is prominent in the spermatocyte, but the envelope is absent in the young spermatid. Mitochondria are present in all germ cell stages and undergo certain morphological changes (e.g., in size and number, presence or absence of cristae), as well as changes in intracellular movements during spermatogenesis. Membranous organelles are prominent in the spermatocyte, but disappear in the older spermatid. Annulate lamellae and a residual body (i.e., cytophore) are conspicuous in the spermatocyte and spermatid, respectively; the spermatozoon clearly lacks a refringent body (i.e., acrosome).
Kinematics of prey capture and chewing in the lizard Agama agama (squamata: Agamidae)
Authors: Kraklau David M.
Published: February 2005

High speed video recordings (200 fields per second) of prey capture and food processing in Agama agama permit the identification of strikes, chews and transport movements. Ten variables from strike movements and seven variables from chewing sequences are digitized; transport movements are inspected only. Univariate and multivariate statistical analyses disclose significant interindividual differences for three variables (maximum gape distance, maximum head angle, and maximum throat distance); but neither these nor principal components analysis show differences between strikes and chews for any of the gape change and hyoid depression variables. However, strikes and chews obviously differ in tongue protrusion and body movements. Chewing may be divided into four stages, comparable to those of transport cycles of other lizards and the generalized tetrapod model. Transport differs from chewing by having a shorter power stroke and relatively more cranial and less jaw movement. The kinematics of feeding in Agama agama are compared with those of other lizards studied previously.
Brain‐capillary architecture of the newt, Triturus cristatus carnifex (Caudata: Salamandridae): Scanning electron‐microscopical study of vascular corrosion casts
Authors: Lazzari Maurizio , Ciani Franco , Franceschini Valeria
Published: February 2005

The brain‐microvascular architecture of the newt (Triturus cristatus carnifex) was studied by scanning electron‐microscopical examination of microvascular corrosion casts. It is characterized at the leptomeningeal level by a superficial network of single vessels that leave the meningeal sheath to form hairpin‐shaped capillary loops. These loops penetrate the nervous parenchyma to varying depths and are variously bent, inclined, and twisted. Each hairpin‐like loop consists of descending and ascending limbs connected by a distal U‐shaped segment. The limbs are of equal diameter and lack physical differentiation. Some loops branch in a secondary loop, but there are no intraparenchymal connections with analogous surrounding structures. On vascular casts we observed detailed imprints of endothelial cell nuclei. This microvascular architecture is present in the whole brain except in leptomeninx and choroidal plexuses. The vascular pattern of T. cristatus carnifex resembles that of apodans. However, it differs from the anuran condition, which is characterized by a three‐dimensional parenchymal network and from that of Ambystoma mexicanum which displays an intermediate condition between a single‐capillary network and a capillary‐loop model. At the level of paired capillaries, a counter‐current exchange system may occur between the two limbs of the same loop, an arrangement that could promote uniformity of extracellular fluid composition in parenchyma.
Cranial ontogeny in the direct‐developing frog, Eleutherodactylus coqui (anura: Leptodactylidae), analyzed using whole‐mount immunohistochemistry
Authors: Hanken James , Klymkowsky Michael W. , Summers Cliff H. , Seufert Daniel W. , Ingebrigtsen Nicole
Published: February 2005

Direct development in amphibians is an evolutionarily derived life‐history mode that involves the loss of the free‐living, aquatic larval stage. We examined embryos of the direct‐developing anuran Eleutherodactylus coqui (Leptodactylidae) to evaluate how the biphasic pattern of cranial ontogeny of metamorphosing species has been modified in the evolution of direct development in this lineage. We employed whole‐mount immunohistochemistry using a monoclonal antibody against the extracellular matrix component Type II collagen, which allows visualization of the morphology of cartilages earlier and more effectively than traditional histological procedures; these latter procedures were also used where appropriate. This represents the first time that initial chondrogenic stages of cranial development of any vertebrate have been depicted in whole‐mounts.

Many cranial cartilages typical of larval anurans, e.g., suprarostrals, cornua trabeculae, never form in Eleutherodactylus coqui. Consequently, many regions of the skull assume an adult, or postmetamorphic, morphology from the inception of their development. Other components, e.g., the lower jaw, jaw suspensorium, and the hyobranchial skeleton, initially assume a mid‐metamorphic configuration, which is subsequently remodeled before hatching. Thirteen of the adult complement of 17 bones form in the embryo, beginning with two bones of the jaw and jaw suspensorium, the angulosplenial and squamosal. Precocious ossification of these and other jaw elements is an evolutionarily derived feature not found in metamorphosing anurans, but shared with some direct‐developing caecilians. Thus, in Eleutherodactylus cranial development involves both recapitulation and repatterning of the ancestral metamorphic ontogeny. These modifications, however, are not associated with any fundamental change in adult morphology and cannot at this time be causally linked to the evolutionary success of this extraordinarily speciose genus.
Histology, histochemistry, and ultrastructure of the harderian gland of the snake Coluber viridiflavus
Authors: Minucci Sergio , Baccari Gabriella Chieffi , di Matteo Loredana
Published: February 2005

Analyses of the histology, histochemistry, and ultrastructre of the Harderian gland of Coluber viridiflavus prove the gland to be compound acinar and to produce a seromucous secretion. Acinar cells (type I) contain secretory granules that are composite, consisting ultrastructurally of three distinct parts that are sharply separated. They are similar to the “special secretory granules” described in the cells of the Harderian gland of the lizard Podarcis s. sicula. Some acini of the most anterior and posterior parts of the gland are mucous. Acinar cells (type II) of this type contain secretory granules that are Alcian blue/PAS positve. At the ultrastructural level, they appear homogeneous and of low density, characteristic of mucous secretions. These mucus‐secreting anterior and posterior parts of the Harderian gland may by considered as regions of intial differentiation of the anterior and posterior lacrimal galnds.