bluuebunny/crossref_metadata_2025 huggingface dataset:
Regeneration of the eighth nerve fibers after transection in the red‐eared turtle, Chrysemys scripta elegans
Authors: Marbey Debra A. , Browner Robert H.
Published: February 2005

The present study examined the time sequence of degeneration and regeneration after transection of the eighth nerve in the red‐eared turtle as well as the chromatolytic reaction of the turtle auditory ganglion cells. Horseradish peroxidase (HRP) transport between auditory ganglion cells and the medulla identified eighth nerve connections. The course of eighth nerve degeneration was followed with Fink and Heimer degeneration stain and HRP reaction. Cresyl‐violet‐stained sections through auditory ganglion cells were observed for chromatolysis.

Degeneration by‐product was intense in the eighth nerve and primary auditory nuclei in turtles surviving 25 and 32 days after eighth nerve transection. Turtles surviving 45 days or less after eighth nerve transection showed HRP reaction product in the eighth nerve to the point of its dorsolateral penetration into the medulla following cochlear duct injections. Acoustic tubercle injections in 50‐day survivors showed HRP filling in eighth nerve and auditory ganglion cells. Cochlear duct injections in 67‐day survivors demonstrated HRP filling in the eighth nerve and acoustic tubercle. Sections stained for degeneration in 67‐day survivors showed little or no degeneration by‐product and 80‐ and 90‐day survivors showed none.

The proportion of chromatolytic auditory ganglion cells was greatest in the 50‐day postoperative turtles when compared to control turtles and other survival stages. Animals which survived longer than 50 days had reduced numbers of chromatolytic cells.

Results suggest that the eighth nerve fibers are regenerated to primary brainstem auditory nuclei in experimental turtles surviving 50 days or more. Regeneration occurs between the 45th and 50th day following transection.
Fine structure of the foveae dorsales and foveal glands in the female tickAmblyomma americanum(acari: Ixodoidea: Ixodidae)
Authors: El Shoura Samir M.
Published: February 2005

The fine structure of the paired foveae dorsales and foveal glands in the unfed femaleAmblyomma americanumis described and compared with that in other tick species. Each fovea opens to the exterior via pores which lead internally into a single cuticular tube, the pore‐tube. This is surrounded by 2–3 epithelial cells. The pore‐tube enlarges basally forming a large cavity possessing a cup‐shaped cytoplasmic protrusion. The pore‐tube cuticular lining extends downward to form an electron‐dense, flaplike protrusion bracketing narrow cytoplasmic extensions filled with microtubules. These extensions form a previously undescribed valvelike structure that seems to control the flow of pheromone secretion from the foveal gland to the pore‐tube.

The single foveal gland lying beneath each pore‐tube is composed of 2–3 inner, large, storage cells surrounded by outer, spindle‐shaped cells; both types of cells have a characteristic feature of epithelia involved in secretory activity and ion transport. The outer cells extend upward to join the base of the poretube cells by septate desmosomes. A nerve, the foveal nerve, containing axons with neurosecretory vesicles occurs in the vicinity of the foveal gland. The secretory activity of the pheromone glands seems to be partially, if not entirely, under a neural regulation.
Observations on the fine structure of the baroreceptors and adrenergic innervation of the guinea‐pig carotid sinus
Authors: Shin H. S. , Hulbert W. C. , Biggs D. F.
Published: February 2005

We examined the fine structure of the baroreceptors and the adrenergic innervation of the guinea‐pig carotid sinus. The tunica adventitia contained many nerve bundles whose perineuria enclosed unmyelinated nerve fibers, alone or together with myelinated nerve fibers. Baroreceptors, which lay close to elastic and collagen fibers in the adventitia and media, were surrounded by “terminal” cells with ultrastructural features characteristic of Schwann cells and contained inclusions of various types. Morphologic features of the baroreceptors included densely packed mitochondria, osmiophilic lamellated and homogeneous bodies, clear and granular vesicles, lamellar systems, glycogen granules, neurofilaments, neurotubuli, and vacuolated mitochondria. In animals that had been treated with 6‐hydroxydopamine, occasional electrondense endings (or fibers) were observed in the adventitial layer. The baroreceptors in the guinea‐pig carotid sinus appear to have most of the morphologic features reported for other species.
Functional characteristics of rat gastrocnemius and tibialis anterior muscles during growth
Authors: De Koning J. J. , Van Der Molen H. F. , Woittiez R. D. , Huijing P. A.
Published: February 2005

Several morphological and functional characteristics of the rat gastrocnemius medialis and tibialis anterior muscle were studied in young, adult, and old rats to assess the influence of growth. Antagonist muscles were studied to determine how changes of muscle architecture and functional characteristics are influenced by the demands of increased body weight and by the specific roles of these muscles in locomotion.

Both muscles change drastically, for instance, in muscle length, volume, physiological cross‐sectional area aponeurosis length, and their muscular geometry changes allometrically for both muscles. The relationships between muscle length, distance between origin and insertion, tendon length, and tibial length also change with growth. Both muscles are rather pennate, so that the increase of physiological cross‐sectional area is a major factor in the determination of muscle length.

No significant difference could be shown for fundamental physiological characteristics (i.e., functional characteristics normalized for muscular dimensions such as maximal work per unit volume). The changes of morphological and functional variables of both muscles parallel each other as is apparent from the index of antagonist characteristics, which is constant for all variables studied with the exception of muscle volume and tendon length.

Consequently, the considerable and similar changes of TA and GM morphology and functional characteristics that take place during growth from approximately four weeks postnatally is not caused by changes of muscular material but by changes of the amount and architectural arrangement of the material involved.
The growth of the skull and jaw muscles and its functional consequences in the New Zealand rabbit (Oryctolagus cuniculus)
Authors: Weijs W. A. , Brugman P. , Klok E. M.
Published: February 2005

Between weaning and adulthood, the length and height of the facial skull of the New Zealand rabbit (Oryctolagus cuniculus) double, whereas much less growth occurs in the width of the face and in the neurocranium. There is a five‐fold increase in mass of the masticatory muscles, caused mainly by growth in cross‐sectional area. The share of the superficial masseter in the total mass increases at the cost of the jaw openers. There are changes in the direction of the working lines of a few muscles. A 3‐dimensional mechanical model was used to predict bite forces at different mandibular positions. It shows that young rabbits are able to generate large bite forces at a wider range of mandibular positions than adults and that the forces are directed more vertically. In young and adult animals, the masticatory muscles differ from each other with respect to the degree of gape at which optimum sarcomere length is reached. Consequently, bite force can be maintained over a range of gapes, larger than predicted on basis of individual length—tension curves. Despite the considerable changes in skull shape and concurrent changes in the jaw muscles, the direction of the resultant force of the closing muscles and its mechanical advantage remain stable during growth. Observed phenomena suggest that during development the possibilities for generation of large bite forces are increased at the cost of a restriction of the range of jaw excursion.
The exocrine glands of Dysdercus cingulatus (Heteroptera, Pyrrhocoridae): Morphology and function of nymphal glands
Authors: Farine Jean‐Pierre
Published: February 2005

The exocrine glandular system of the nymphs and the adults of Dysdercus cingulatus were studied. The D. cingulatus nymphs present 3 dorso‐abdominal glands (lying under the 3rd, 4th, and 5th abdominal terga) and a pair of dorso‐lateral pygidial glands on the pygidium (tergum 8). Histological and ultrastructural studies show that the upper and lower walls of the dorso‐abdominal glands differ in structure; 3 types of cells were described: epidermal cells, unicellular secretory cells, and multicellular secretory units. Each of these exocrine glands plays an important part in the behavior of the nymphs (gregariousness, alarm, defense). The morphology of the various glands is discussed, and the chemistry of their secretions and their biological functions are considered.
TheJournal of morphologyas window and mirror: Reflections and glimpses on the birth of american biology
Authors: Benson Keith R.
Published: February 2005

The centennial of theJournal of Morphologyprovides a fitting occasion to reflect upon the condition of American biology surrounding the founding years of theJournal.TheJournalwas started by C.O. Whitman in 1887. At this same time, the American biological community experienced a gradual change from a community of amateurs based within the natural history tradition to a professional community based within universities with specialized research programs. Many of the changes associated with this maturation process are exhibited in the pages of the first ten volumes of theJournal.They show that theJournalplayed a central role in communicating research methods and questions to the growing community of professional biologists. Moreover, these same volumes provide an accurate record of the character of the morphological sciences at the end of the 19th century.
Functional mechanisms and histologic composition of the lingual appendage in the alligator snapping turtle, Macroclemys temmincki (Troost) (Testudines: Chelydridae)
Authors: Spindel Edward L. , Dobie James L. , Buxton Donald F.
Published: February 2005

Gross and microscopic examination of the lingual appendages of juvenile and adult alligator snapping turtles, Macroclemys temmincki, shows that it is divided into an anterior horn, a body, and a posterior horn. Lingual appendages of adults usually are more darkly pigmented than those of juveniles and melanocyte distribution is variable, resulting in a mottled appearance. The musculoskeletal components of the hyoid apparatus, presumably responsible for most of the motion displayed by the appendage, are described here. The lingual appendage is innervated by the lingual nerve which divides into three branches, two coursing rostrally into the anterior horn and one running caudally into the posterior horn. These branches ramify and end in numerous terminals within the lamina epithelialis and lamina propria. The lamina epithelialis of the distal three‐fourths of the horns of the lingual appendage contain structures similar to taste buds described in other species of turtles. Goblet cells, containing acid mucopolysaccharides, are located in the stratified squamous epithelium. Blood is transported to the appendage via the lingual artery, which is a terminal branch of the external carotid artery. Numerous venous sinuses lie among the predominant bundles of connective tissue and account for approximately one‐fifth of the total volume of the appendage. An engorged appendage is swollen and pinker in color.

The coloration, enlargement, and wiggling movement combined with its buoyancy in water make the appendage imitate a small worm or an insect larva. The increase in melanin during ontogeny may produce a more variable pattern and may increase the number of organisms attracted by the appendage. The acid mucopolysaccharides of the globlet cells presumably may condition the nonkeratinized, stratified squamous epithelial surface of the appendage. The flexibility of the pseudoerect, active appendage keep it from being injured.
Gross and ultrastructural development of the saccule of the toadfish Opsanus tau
Authors: Sokolowski Bernd H. A. , Popper Arthur N.
Published: February 2005

The development of the saccule of the inner ear in the toadfish was studied using light and scanning electron microscopy. Development was studied from the early embryo (2–3 days postfertilization), when the otocyst first forms, to the early‐aged juvenile when the development of the inner ear approximates that of the adult (4 weeks postfertilization). The ultrastructural features examined included the morphological sequence of ciliary bundle growth, the development of orientation patterns of the ciliary bundles, and the relation of the ultrastructural development to overall gross development.

Gross development may be divided into four distinct morphological stages. Stage I encompasses the time from initial formation of the otocyst until the start of stage II, which is the stage when the pars inferior begins migrating ventrally. In stage III the pars inferior continues to elongate ventrally. Stage IV starts when the pars inferior elongates in a rostral and caudal direction. The ear attains its adult shape in stage IV.

The differentiation of the sensory cells begins during stage I. During the early part of stage I, a small cilium is found on the apical surface of each cell throughout the otocyst. In the middle and late periods of stage I, a few micro—villous buds add to the surface of the cells that already have a kinocilium. These early ciliary bundles are clustered on the rostral—ventral and caudal walls of the otocyst. There is no clear patterning to the orientation of these ciliary bundles. In stage II the ventral stretching of the labyrinth wall causes a spreading of the clustered bundles along the ventral and medial walls of the pars inferior. The orientation of the ciliary bundles has no distinct pattern. In stage III the orientations of the ciliary bundles appear adultlike, although there are so few ciliary bundles that it is difficult to make a definite determination. During stage IV, hair cells with an adultlike horizontal and vertical orientation pattern are found on the rostral and caudal sections of the saccular macula, respectively. The transition region lying between these areas has ciliary bundles with various orientations.
Morphology of the oral disc of Bufo bufo (Salientia: Bufonidae) tadpoles
Authors: Marinelli M. , Vagnetti D.
Published: February 2005

The fully developed oral disc of the tadpole of Bufo bufo consists of dorsal and ventral labia bearing, respectively, two and three ridges bearing numerous horny denticles, a horny beak provided with jaw sheath serrations, and large lateral papillae that are borne by two cutaneous plicae. As development progresses toward metamorphosis, these structures gradually regress until they disappear. Each cusped clavate labial denticle adheres, by means of a thin peduncle, to a similar labial denticle fixed in the lip and formed by a group of three or four cells that keratinize gradually and thus present remarkable differences in their morphology. Once all the cells of a group have been converted into horny tissue, the denticle sheds and is replaced by the underlying one. The beak serrations also are horny structures; each consists of a columnar band of cells which undergoes a gradual keratinization. The horny cells that detach themselves at intervals, being replaced by those of the underlying anlagen. The labial denticles and the beak serrations keratinize in two distinct ways. In the former, the desmosomal filaments appear to play an important role whereas, in the latter, the keratin seems to be synthesized “ex novo” by the ribosomes.
Morphological and videofluorographic study of the hyoid apparatus and its function in the rabbit (Oryctolagus cuniculus)
Authors: Anapol Fred
Published: February 2005

The anatomy of the hyoid apparatus and positional changes of the hyoid bone during mastication and deglutition are described in the New Zealand White rabbit (Oryctolagus cuniculus). A testable model is constructed to predict the range of movement during function of the hyoid, a bone entirely suspended by soft tissue. Frame‐by‐frame analysis of a videofluorographic tape confirms the accuracy of the prediction through observation of hyoid bone excursion during oral behavior.

During chewing, translation of the hyoid bone is diminutive and irregular, lacking a clearly discernible path of excursion. However, some movements of the hyoid occur with regularity. During fast opening, anterodorsal movement of the hyoid is interrupted with an abrupt posteroventral depression when the bolus is moved posteriorly toward the cheek teeth by the tongue. This clockwise rotation (when viewed from the right side) of the hyoid accompanies jaw opening and is reversed (posteroventral movement) for the jaw closing sequence. Lateral movements of the hyoid may be slightly coupled to mandibular rotation in the horizontal plane.

The findings suggest that the hyoid bone maintains a relatively static position during the dynamics of chewing. The primary function would be to provide a stable base for the movements of the tongue. Another possible function would be to control the position of the larynx within the pharyngeal cavity. Some characteristic features of the rabbit hyoid apparatus may be consequential to relatively erect posture and a saltatory mode of locomotion.
Ultrastructure of the sensory complex on the maxillary and labial palpi of the colorado potato beetle, Leptinoarsa decemlineata
Authors: Sen A.
Published: February 2005

Sensilla on the maxillary and labial palpi of Leptinotarsa decemlineata were examined by scanning and transmission electron microscopy. There are a total of 370 sensilla on the apical tip of the maxillary palpi and 130 on the labial palpi. Four morphologically different types of sensilla are present on the maxillary palpi, three of which are common to the labial palpi. Type A sensilla, unique to the maxillary palpi, and type C sensilla have the structural characteristics of olfactory sensilla. Types B and D, with an apical pore, are considered contact chemoreceptors. Cuticular specializations, interrelationships of enveloping cells, comparative morphometry of dendrites, distribution of each sensillar type, and the predominance of olfactory sensilla are discussed in relation to feeding behavior.
Morphology of the pronephros of the juvenile brown trout, Salmo trutta
Authors: Tytler Peter
Published: February 2005

The pronephros in juvenile brown trout (Salmo trutta) consists of a large ovoid renal corpuscle and a pair of tubules. The corpuscle is retained for 11 months, after which the glomerulus regresses. The glomerular arteries come directly from the dorsal aorta. The interstitium is permeated with venous blood vessels that arise from the anterior cardinal veins and are closely apposed to the tubules. Two distinct segments of the pronephric tubular system are distinguished by the histological and ultrastructural features of their component cells: (1) a short, transitional neck in which cells change from capsular epithelium to columnar epithelium, typical of tubules; (2) the convoluted segment composed of cells similar to first proximal tubular cells of the opisthonephros with well‐formed brush borders, apical vesicles that vary in size and number along this segment, and lysosomes. Pinocytosis and exocytosis are also evident in this segment. The tubular system increases in length and in its convolutions until about week 9, when the opisthonephros develops. Distally each tubule connects with a Wolffian duct, with cells marked by the absence of apical inclusions and the presence of a uniform brush border, numerous mitochondria, and elaborate infolding of the basalar membrane. Nephrostomes, which are often characteristic of pronephroi, are not present. Cells with long cilia are found throughout the tubular system but are most characteristic of the neck and Wolffian‐duct segments.
A comparison of the structure of the spermatozoa and spermatogenesis of 16 species of patellid limpet (Mollusca: Gastropoda: Archaeogastropoda)
Authors: Hodgson A. N. , Bernard R. T. F.
Published: February 2005

Light and transmission electron microscopy of the spermatozoa and spermatogenesis of 16 species (in three genera, Patella, Helcion, Cellana) of patellid limpet have shown that head lengths of the sperm range from 3 to 13 μm, and each species has a sperm with a unique morphology, indicating that the spermatozoa can be used as a taxonomic character. Although spermatozoon structure is species specific, five types can be recognized, based on the size, shape, and structure of the nucleus and acrosome. The occurrence of five morphological types of sperm, one of which (Cellana capensis) is particularly different from other patellids, suggests that the taxonomy of the family Patellidae be re‐examined. The morphological changes that occur during spermatogenesis are very similar in all species, although two patterns of chromatin condensation are found. Those species with sperm that have short squat nuclei (length:breadth < 3.5:1) have a granular pattern of condensation. Species with sperm that have more elongate nuclei (length:breadth > 5:1) have an initial granular phase followed by the formation of chromatin fibrils. These fibrils become organized along the long axis of the elongating nucleus. The absence of a manchette suggests that nuclear elongation is brought about from within the nucleus.
Arterial and venous vasculature of the heart of the beluga whale (Delphinapterus leucas)
Authors: Bisaillon André , Martineau Daniel , Le St‐Pierre Michè A. , Béland Pierre
Published: February 2005

The arteries and veins of the heart of the beluga whale (Delphinapterus leucas) are described from the dissection of nine specimens. The arterial distribution is composed of the basic mammalian pattern of two major vessels, the left and right coronary arteries, which supply the cardiac tissue. The venous drainage is provided by three major systems which are the great, middle, and small cardiac veins. The vascular characteristics of the heart of the beluga whale are the marked sinuosity of both coronary arteries and their main branches, the numerous large interarterial anastomoses between major vessels, and the duplication of vessels in parallel branches. These characteristics are discussed in functional terms and correlated with the diving ability of the species.
Multicellular complex of chloride cells in the gills of freshwater teleosts
Authors: Hwang Pung‐Pung
Published: February 2005

Morphology of branchial chloride cells in the freshwater teleosts Plecoglossus altivelis, Cyprinus carpio, and Oreochromis mossambicus was studied by light and transmission electron microscopy. The chloride cell has an apical membrane directly in contact with the outer medium. Generally, two or more neighboring chloride cells share an apical pit, forming a multicellular complex. The chloride cells form a multicellular complex in which cells differ in cytoplasmic electron density, development of tubular system, and in cell size. Chloride cells are linked by junctions which are shallower than the tight junctions that occur between neighboring pavement cells or between pavement and chloride cells. Multicellular complexes of chloride cells create additional paracellular pathways marked apically by the shallower junctions. Since junctional structure affects transepithelial permeability, development of multicellular complexes of chloride cells in freshwater fishes may be related to the transport of some substances as in the gills of marine fishes.
The buccopharyngeal mucosa of the turtles (Testudines)
Authors: Winokur Robert M.
Published: February 2005

Gross and histological examination of all extant families of turtles revealed that the buccopharyngeal mucosa is morphologically highly varied. The tongues of aquatic species have small lingual papillae or lack them entirely, while terrestrial species have tongues with numerous glandular papillae. The pharynx and the esophagus also have papillae in some species. These either facilitate swallowing in which case they are long, pointed, keratinized, and occur commonly in marine turtles, or they are vascular and nonkeratinized, facilitate respiratory gas exchange and are found in the Trionychidae, Dermatemyidae, and Carettochelyidae. The morphology of the buccopharyngeal mucosa of turtles reflects their diet, feeding behavior, habitat, and relationships. Convergence in the morphology of the buccopharyngeal mucosa occurs among families, especially among the Emydidae and other familes of turtles. Intergeneric parallelism is also seen within the Emydidae.
Trophoblast concept as applied to therian mammals
Authors: Blackburn Daniel G. , Taylor J. Mary , Padykula Helen A.
Published: February 2005

Available evidence provides little support for a recent proposal that the term “trophoblast” be applied solely to eutherian mammals. Arguments for such a restricted usage are based on a dichotomous interpretation of therian reproduction that underestimates the developmental, structural, and functional diversity of trophoblastic tissues occurring within the infraclass Eutheria. The occurrence of developmental patterns that are phenotypically intermediate between those of commonly studied eutherians and metatherians suggests that blastocyst development is not fundamentally different in marsupials and eutherians.

The trophoblast of marsupials accomplishes most or all of the major functions of the eutherian trophoblast, including maternal‐fetal physiological exchange, implantation, contribution to placental membranes, steroid metabolism, and possibly, immunological protection of the conceptus. Furthermore, application of the term “trophoblast” to marsupials is consistent with present and past usage, as well as with the original definition and etymological derivation of the term. Therefore, we recommend that the term “trophoblast” continue to be applied in a functional‐morphological sense to the appropriate extraembryonic tissues of marsupials. Such use of functional (rather than taxonomic) criteria for application of this term avoids biasing interpretations of mammalian reproductive evolution.
Form and function of the tongue in agamid lizards with comments on its phylogenetic significance
Authors: Smith Kathleen K.
Published: February 2005

The morphology of the tongue of agamid lizards is reviewed and discussed in the context of its functional and phylogenetic significance. It is shown that in several features, including the development of the central musculature of the tongue into a ring muscle and the presence of a genioglossus internus muscle in adults, the tongue in most agamids is derived relative to that in other squamates. In some features, such as the vertical connective tissue septa, agamids share primitive features with Sphenodon. Some conditions found in agamids are also found in anoline iguanids. Two genera, Uromastyx and Leiolepis, differ significantly from other agamids in intrinsic tongue musculature.

The functional significance of the unique tongue morphology is that agamids utilize a different mechanism of tongue protrusion from that of other lizards. This mechanism involves the production of force against the lingual process, leading to an anterior slide of the tongue, and is detailed in this paper. Finally, I discuss the mechanical basis for the transformation series of tongue protrusion mechanisms from agamids to chamaeleonids. It is suggested that the mechanism of tongue protrusion in chamaeleonids is not unique, but is a highly derived state of the condition found in agamids.
Intercellular bridges and factors determining their patterns in the grasshopper testis
Authors: Carlson J. Gordon , Handel Mary Ann
Published: February 2005

Intercellular bridges joining cells contained in cysts of Chortophaga viridifasciata testes were studied with light and electron microscopy. Preparations consisted of expressed whole cells (living, or fixed and stained) as well as sections. The secondary spermatogonia of each cyst are joined centrally by persisting fused interzonal bodies (fusomes) of incompletely cleaved cells. Shifts in cell orientation during anaphase are apparently responsible for central as opposed to chain linkage of cells. In the primary spermatocytes, the central fusome is replaced by a chain linkage, apparently resulting from the breakdown of the fusome into its original interzonal body components. Intercellular bridges are also present in spermatids, but there is no evidence to indicate the time of their formation (in the immediately preceding meiotic divisions or in the secondary spermatogonial divisions). The function of the compact centrally situated fusome in the secondary spermatogonial cyst is discussed as it relates to synchrony, number of cell divisions, spermatodesm formation, and fertility.
External observations on the formation of statoblasts in Plumatella emarginata (Bryozoa, Phylactolaemata)
Authors: Mukai Hideo , Kobayashi Kumiko
Published: February 2005

Using laboratory‐grown colonies of Plumatella emarginata, the formation of the floatoblast and the sessoblast was studied. Both types of statoblast develop in the funiculus. Toward the termination of development, the floatoblast secretes a gas and the float chambers are filled with the gas in about 20–30 minutes. The floatoblast thus complete is separated from the funiculus. Until early epidermal‐disc‐stage, distinction between a floatoblast and a sessoblast is impossible at least morphologically. Toward the late epidermal‐disc stage, a future sessoblast becomes larger than a future floatoblast and attaches by its cystigenic side to the cystid. Very often it initially attaches to a lateral wall, then migrates to the basal wall of the cystid. Both the attachment to and the migration along the cystid wall are attained by peritoneal cells covering the sessoblast, specifically by those in the marginal zone of the cystigenic side. The sessoblast is separated from the funiculus precociously, shortly after attachment to the cystid. Then, it produces the capsule, followed by the formation of both the lamella, a homologue of the float in the floatoblast, and the attaching apparatus.

Almost all polypides produce floatoblasts (up to 17 in number), but only a small portion of them produce both floatoblasts and sessoblasts. The number of sessoblasts produced by a single polypide is usually not more than 3 but occasionally reaches up to 6. When multiple sessoblasts are formed by a polypide, they are as a rule derived from primordia located adjacently on the funiculus, accordingly successively in a short period, but their arrangement on the basal wall of the cystid does not always correspond to that on the funiculus. Sessoblast formation is never associated with the death of the mother polypide. Ancestrulae derived from statoblasts never produce mature statoblasts, though may undergo gametogenesis. Several mosaic statoblasts consisting of floatoblast‐ and sessoblast‐portions were found in some species of the Plumatellidae. A primordium of the statoblast seems to have a dual ability of differentiating into either a floatoblast or a sessoblast; but little has been known about the mechanism or factors controlling the formation of these two types of statoblasts.
Ocular morphology in antarctic notothenioid fishes
Authors: Eastman Joseph T.
Published: February 2005

Beneath the sea ice at McMurdo Sound, Antarctica, notothenioid fishes are subject to extreme seasonal variation in the annual light cycle including 4 months of continual darkness. Gross and microscopic anatomy of the eyes of 18 species revealed ocular morphology that was generally similar to that of coastal fishes elsewhere in the world, and unlike that of deep sea fishes living in perpetual darkness. The spectacle was well developed as were hyaloid arteries at the vitreoretinal interface. Fourteen species had a choroid body, and its presence was considered a primitive character state for notothenioids. The choroid body was absent in phyletically derived groups. The choroid body was especially large in Dissostichus mawsoni, the only species with a rod dominated retina. Retinae were 154–279 μm thick with layering and sublayering typical for teleosts. Although all species had both rods and cones, there was marked interspecific variation in the ratio of cones:rods and in the total number of visual cells. Non‐Antarctic notothenioids from New Zealand had more visual cells than most species from McMurdo Sound. Retinae appeared balanced for vision under dim but seasonally variable light conditions and not specially adapted to the 4‐month period of winter darkness. Retinal histology reflected the ecology and depth range of most species. Based on ecology and retinal histology, four groups of species were recognized: (1) Non‐Antarctic, (2) cryopelagic (including two visually oriented benthic species), (3) pelagic and benthopelagic, and (4) benthic.
Ultrastructure of spermatozoa of the lung fluke, Paragonimus ohirai (Trematoda: Troglotrematidae), in the seminal receptacle
Authors: Orido Yasuhide
Published: February 2005

The seminal receptacle of Paragonimus ohirai contains not only mature spermatozoa, but also atypical and degenerate ones, suggesting that abnormal spermatozoa are retained in this organ. The spermatozoon is of a parallel biflagellar type with cortical microtubules, consisting of the anterior region, first mitochondrial region, intermediate (amitochondrial) region, second mitochondrial region, posterior nuclear region (PNR) and tail region (TR). The first third of the spermatozoon exhibits typical undulatory movement, while the middle part shows vibratory movement. At the area between head and midsections (H‐M area) the peripheral doublets of axonemes are interrupted, and the external ornamentation is distributed widely around this portion. Throughout the immotile PNR and TR, the axonemes lack the dynein arms of their peripheral doublets. H‐M, PNR, and TR ultrastructural characteristics are specific in P. ohirai spermatozoon and seem to be closely related to its pattern of movement.
Distribution and ultrastructure of neurosecretory cells in the cerebral ganglion of the earthworm
Authors: Al‐Yousuf Shoaa
Published: February 2005

Neurosecretory (Nsy) cells within the cerebral ganglion of Lumbricus terrestris were classified ultrastructurally. The Nsy cells within the subesophageal ganglion, nerve cord ganglion, and the peripheral nervous system were also examined. A comparative survey of Nsy cells of four other species of oligochaetes, Eisenia feotida, octolasion cyaneum, Dendrobeona subrubicunda, and Allolophora longa, was also carried out. Seven cell types (A1, A2, A3, A4, A5, C, and SEF), distinguished by special cytological and ultrastructural features, were found within the cerebral ganglion. Distribution of these cells inside and outside the cerebral ganglion was studied in detail by light and electron microscopy. The nerve terminals of each cell type were followed into the neuropile region. Exocytosis from cell bodies appears to be the main release mechanism for the Nsy granules, whereas small Nsy vesicles are released through synapses in the neuropile. Peripheral fibers of some cell types (A1, A2, and A3) extend through the capsule to the pericapsular epithelium. It is possible that Nsy cells secrete hormones from their cell bodies and peripheral processes and that their centrally directed axons release modulators/transmitters within the neuropile.
Labral glands in Centropages typicus (Copepoda, Calanoida). I. Sites of synthesis
Authors: Arnaud Jean , Brunet Michel , Mazza Jacques
Published: February 2005

In Centropages typicus the labrum contains two symmetric gland clusters on the right and left sides. Each cluster comprises two principal elements: a vast unit (AU) located in the anterior, distal area and a dozen smaller units (LPU) in the lateral, posterior area. All these glandular units empty through several pores situated on the labrum. In addition, other secretory units (LDU) are observed in a more dorsal and posterior zone at the level of the perioesophageal nerve ring, and hence outside the labrum itself; these LDU probably secrete through the dorsal side of the stomodeum. All the glandular units (i.e., AU, LPU, and LDU) are organized in syncytia. They have the typical ultrastructural features of a secretory system (rough endoplasmic reticulum, numerous dictyosomes, and secretory granules, the latter amassed at one pole), and several stages of activity may be characterized. The biochemical composition of the products synthesized by rough endoplasmic reticulum and Golgi apparatus is probably very complex. Mucopolysaccharides and glycoproteins both appear to be contained in a single type of grain. The mucopolysaccharides would cause agglutination of food particles carried up to the stomodeum by water currents. The glycoproteins would consist of different enzymes functioning in a preliminary digestive phase occurring before the aliments enter the midgut.
Sequence of ontogenetic development and atrophy of the oral apparatus of six anuran tadpoles
Authors: Thibaudeau D. Giselle , Altig Ronald
Published: February 2005

The development of the oral structures of six species of anuran tadpoles with four different types of mouth parts and the metamorphic atrophy of these structures in two species with different mouth parts are described. The oral labia of typical tadpoles, oral flaps of microhylids, and lateral oral folds ofRhinophrynusare assumed to be homologous. We also suggest that the barbels of the tadpoles ofRhinophrynusare homologs of the marginal papillae of species with an oral disc. Developmental patterns and sequences of the oral structures of all tadpoles examined follow a common pattern: stomodeal invagination, oral pad development, jaw sheeth delimitation, tooth row ridge development, jaw sheath keratinization, and labial tooth keratinization. Developmental patterns remain constant, while interspecific differences are apparent because of truncations of ontogeny at specific stages. Metamorphic atrophy of oral structures occurs roughly in the reverse order of development, although the procedure is rapid and more haphazard than development.
Bryozoan larvae as mosaics of multifunctional ciliary fields: Ultrastructure of the sensory organs of Bugula solonifera (Cheilostomata: Cellularioidea)
Authors: Reed Christopher G. , Ninos John M. , Woollacott Robert M.
Published: February 2005

The ultrastructure of ciliated sensory and effector organs has been examined by light microscopy and by scanning and transmission electron microscopy in larvae of the cellularioid cheilostome, Bugula stolonifera. The larval surface is formed by a mosaic of ciliary fields, each distinctive in organization and function. The most extensive ciliary field consists of the motile cilia of the corona, which collectively constitute the primary larval locomotory organ and form most of the larval surface. The corona is innervated basally by a nerve ring that circumscribes the larval equator. A circular field of immotile shorter cilia at the aboral pole arise from bands of radial cells in the apical disc. The radial ciliated cells form chemical synapses with underlying nerves of the paired aboral nerve cords, which extend to an equatorial nerve plexus on the median anterior side of the larva, beneath the pyriform organ. The pyriform organ is a complex of ciliated and glandular regions aligned along the anterior midline of the larva. It consists of, in aboral to oral sequence: the superior glandular field, the vibratile plume, the inferior glandular field, and the ciliated cleft. The vibratile plume is distinctive from the surrounding ciliation by its length and pattern of beating. It consists of four bundles of cilia approximately 64 μm long that beat rhythmically in synchrony into the ciliated cleft. Each bundle of cilia arises from a single cell which is further distinguished by apical pits of stout microvilli. The glandular fields and the vibratile plume are bordered by a variety of previously undescribed ciliated cells, longitudinal myoepithelial cells, and a pair of antero‐medial eyespots. Another type of ciliated sensory cell is located between cornal cells. These intercoronal cells form synapses directly with the adjacent coronal cells. On the basis of these ultrastructural observations, the radial ciliated cells of the apical disc and the intercoronal cells are classified as primary sensory cells with different motor pathways. The radial ciliated cells are associated with the various effector organs of the larva via the nervous system. The intercoronal cells may combine sensory and motor functions by synapsing directly with the larval locomotory organ.
Paraphalangeal elements of gekkonid lizards: A comparative survey
Authors: Russell Anthony P. , Bauer Aaron M.
Published: February 2005

Paraphalanges of gekkonid lizards are cartilaginous structures associated with interphalangeal joints. Their form and structure have been investigated by dissection, cleared‐and‐stained specimens, routine histoloty, and radiography. A family‐wide survey revealed that paraphalangeal elements occur in at least 57 species in 16 genera of the subfamily Gekkoninae. The distribution and structure of these elements suggests multiple origins among gekkonine geckos. In most instances, they are present in species with expanded subdigital climbing pads, divided scansors, and a markedly raised penultimate phalanx that is elevated from, or free of, the pad. Thus, they seem to be associated with placement of the scansors onto the locomotor substrate. In two genera, Uroplatus and Palmatogecko, paraphalanges at the more proximal interphalangeal joints are associated with muscles that run between them. In these cases, the paraphalanges appear to be involved in grasping abilities of the foot associated with digging and climbing modifications.
Ontogeny of functional design in tiger salamanders (Ambystoma tigrinum): Are motor patterns conserved during major morphological transformations?
Authors: Lauder George V. , Shaffer H. Bradley
Published: February 2005

The process of metamorphosis in tiger salamanders, Ambystoma tigrinum, is used to investigate motor pattern conservatism in vertebrates. Specifically, we examined cranial muscle activity to determine if changes in the motor pattern are correlated with the morphological or environmental changes that occur at metamorphosis.

Twenty‐three variables were measured from electromyographic recordings from six cranial muscles in 13 tiger salamanders. These variables described the configuration of the motor pattern: the peak amplitude of activity, duration, relative onset, and time to peak amplitude were measured for each of the six muscles. Univariate and multivariate statistical analyses showed that there was no change in the mean motor pattern associated with the morphological transformation at metamorphosis: larval and metamorphosed individuals feeding in the water have very similar motor patterns. This was true despite significant morphological changes in the design of the feeding mechanism at metamorphosis and despite a significant decrease in aquatic feeding performance following metamorphosis.

There was a change in the mean motor pattern to jaw muscles when metamorphosed individuals fed in water and on land: metamorphosed terrestrial feedings tend to have longer bursts of muscle activity then do aquatic feedings. The environmental changes in the motor pattern cannot be attributed to effects of differing fluid density or viscosity between water and air and are instead related to the shift to feeding by tongue projection on land.

The decrease in aquatic feeding performance that occurs after metamorphosis is not correlated with changes in the motor pattern. Instead, the results suggest that changes in behavioral performance during ontogeny are associated with the transformation of hydrodynamic design of the feeding mechanism from uni‐ to bidirectional, and that motor patterns driving complex rapid behaviors may be conserved when behavior is altered by changes in peripheral morphology.
Ultrastructure of the branchial wall of a lower chordate: The ascidian Ciona intestinalis
Authors: Pestarino Mario , Fiala‐Medioni A. , Ravera F.
Published: February 2005

Transmission electron micrographs show the branchial epithelium of the ascidian Ciona intestinalis to be composed of three kinds of cells: ciliated, parietal, and “dark.” Absorptive processes of phagocytosis appear in ciliated and parietal cells; moreover, apocrine‐like secretion is evident exclusively in the parietal cells. Finally, the occurrence of secretory cells in the branchial epithelium suggests a digestive role of the ascidian branchial sac.
The role of cellular parenchyma and extracellular matrix in the histogenesis of the paruterine organ of Mesocestoides lineatus (Platyhelminthes: Cestoda)
Authors: Conn David Bruce
Published: February 2005

The cellular parenchyma of adult Mesocestoides lineatus consists primarily of muscle cells divided into myofibrils, myocytons with numerous greatly dilated cisternae of granular endoplasmic reticulum, and glycogen‐rich myocytons with lipid droplets and membranous whorl inclusions. The latter are connected to each other by numerous gap junctions. Other mesenchymally arranged cells in the parenchyma are calcareous corpuscle cells. The extracellular matrix (ECM) consists of an electron‐lucent ground substance and numerous filaments. During histogenesis of the paruterine organ wall, the myocytons surrounding the posterior end of the uterus undergo extensive flattening, followed by cellular deterioration. There is a concomitant reduction in ECM/cell ratio. The paruterine organ lumen dilates and then its uterine epithelium breaks down as the wall thickens, so that the late gravid paruterine organ consists of a thick wall of membranous sheets enclosing the egg mass. Parenchymal cells in other regions of the proglottid do not undergo change. These data provide evidence for epithelial‐mesenchymal‐ECM interactions in the development of an epithelio‐mesenchymal organ in the Platyhelminthes.
Ultrastructure of the nymphal integument in the camel tickHyalomma(Hyalomma)dromedarii(Ixodoidea: Ixodidae)
Authors: El Shoura Samir M.
Published: February 2005

The ultrastructure of the nymphal integument in the ixodid tickHyalomma(Hyalomma)dromedariiis compared for stages of development during and after feeding, and up to the first step of molting, apolysis. The integument comprises a cuticular layer and underlying epidermal cells. The body cuticle, which consists of both sclerotized and non‐sclerotized parts, is divided into an outer, thin epicuticle, and an inner, thick, fibrillar procuticle. Pore canals in the procuticle are continuous with wax canals which traverse the epicuticle. As feeding progresses, the parallel, extensible epicuticular folds disappear due to the gut filling with ingested blood. The procuticular zone, however, becomes subdivided into an exocuticle, similar to the previously seen procuticle, and a lamellate endocuticle. Pore canals lose their parallel pattern and appear to have become deformed by stretching of the cuticle.

The flat epidermal cells grow asynchronously during feeding; their cytoplasm becomes packed with well‐developed rough endoplasmic reticulum (RER), while the cell apices project long microvilli extending deep into the procuticle. The RER undergoes ultrastructural changes indicating synthetic activity. Dense material released through the microvilli may serve to lyse the endocuticle and thus cause separation of the cuticle from the epidermis during apolysis. The lysed area, the exuvial cavity, is filled with lysed components which are probably withdrawn by endocytosis into the apical coated vesicles which appear in epidermal cells. Two types of integumental glands, which may participate in wax production, are observed in this study. The ultrastructure of their previously undescribed cuticular ducts is described, in addition to other hypodermal structures including epidermis‐muscle attachments and sensory receptors.