ALBERT

Notizen: Study of the visceral anatomy of 41 specimens of amphisbaenians representing 13 genera shows that they share a very distinct structure which differs from that found in either snakes or typical lizards. The left lung is large while the right is rudimentary or absent (unique); the kidneys are freely suspended in the coelom by a mesentery (unique); the spleen is usually embedded in the anterior end of the pancreas (as in snakes); the gall bladder lies in a notch in the liver, and the kidneys lie opposite each other (as in lizards). The distinctness of this pattern supports the recognition of the Amphisbaenia as a separate suborder of the Squamata.

Notizen: Light and electron microscope studies were made on harvestman oocytes during the course of their origin, differentiation, and vitellogenesis. The germ cells appear to originate from the ovarian epithelium. They subsequently migrate to the outer surface of the epithelium, where they remain attached often by means of stalk cells which suspend them in the hemocoel during oogenesis. The “Balbiani bodies,” “yolk nuclei,” or “nuage” constitute a prominent feature of young, previtellogenic oocytes, and take the form of large, but variable sizes of electron-dense cytoplasmic aggregates with small fibrogranular components. The cytoplasmic aggregates fragment and disperse, and cannot be detected in vitellogenic oocytes. The young oocytes become surrounded by a vitelline envelope that appears to represent a secretory product of the oocyte. The previtellogenic oocytes are impermeable to horseradish peroxidase under both in vivo and in vitro conditions. In addition to mitochondria, dictyosomes, and abundant ribosomes, the ooplasm of the previtellogenic oocyte acquires both vesicular and lamellar forms of the rough-surfaced endoplasmic reticulum. In many areas, a dense homogeneous product appears within the cisternae of the endoplasmic reticulum and represents nascent yolk protein synthesized by the oocyte during early stages of vitellogenesis. Later in vitellogenesis, the oocyte becomes permeable to horseradish peroxidase under both in vivo and in vitro conditions. This change is associated with a massive process of micropinocytosis which is reflected in the presence of large numbers of vesicles of variable form and structure in the cortical ooplasm. Both spherical and tubular vesicles are present, as are coated and uncoated vesicles. Stages in the fusion of the vesicles with each other and with developing yolk platelets are illustrated. In the harvester oocytes, vitellogenesis is a process that involves both autosynthetic and heterosynthetic mechanisms.

Notizen: The clitellar epithelium of the freshwater oligochaete, Tubifex hattai, is composed of four types of gland cells (Type I, II, III, and IV), in addition to the cells generally found in the epidermis of this worm. The possible function of these gland cells in cocoon formation was studied with the electron microscope.Type I cells discharge their secretory granules by means of compound exocytosis and provide the materials for the future cocoon membrane. Immediately after completion of the discharge from Type I cells, Type II and III cells simultaneously discharge their secretory granules by means of compound exocytosis. The secretions from Type II cells constitute a colloid in the cocoon lumen and probably cause structural modifications in the future cocoon membrane. The secretory products from Type III cells form the cocoon plug. Although the process of discharge of secretory granules from Type IV cells was not observed, the contribution of these cells to the cocoon formation, producing hoops on the outer surface of the future cocoon membrane and fixing its anterior ends on the clitellum, is inferred from a morphological comparison of the hoop and the structure of the secretory granules.

Notizen: The distribution and activity patterns of monoamine oxidase and monoaminergic (formaldehyde-induced) fluorescence in the central nervous system of web-building and hunting spiders have been studied using histochemical methods. Enzyme activity occurred in the neuronal perikarya and in varying intensity in the structures of the neuropile mass, but only when dopamine, adrenaline, and noradrenaline were used as substrates. The optic centres of the spider brain normally exhibited relatively strong enzyme reactions when compared with the staining intensity of the rest of the nervous system.The neuronal cell bodies contained numerous granules of yellow-green fluorescence. Monoaminergic fluorescence of the neuropile was generally a weak green. The optic mases of the hunting spiders, the anterior bridge, several commissures of the ventral cord, and the neural lamellae showed a slightly higher fluorescence intensity and single fluorescing granules.The results obtained indicate the presence of catecholamines in the spider nervous system.

Notizen: The tongue of the striped dolphin, Stenella coeruleoalba, shows a V-shaped row of pits on its posterior dorsum. Their development is described on the basis of macroscopic and light microscopic observations on fetal, young, and adult stages. Four to eight pits occur, most often five in the adult. Anlagen of the pits first protrude as round epithelial thickenings which later increase in diameter and become thin. The circular primordia then sink, and grooves oriented both circularly and radially develop in the walls of the shallow pits thus formed. Pits and grooves deepen with development so that older pits become lined with conical projections. As pits grow further, they become elongated anterolaterally, retaining slit-like openings. Each pit in the adult is 2-8 mm long and about 1 mm wide. The pits are not derived from lingual gland ducts but develop independently. Taste buds resembling those of other mammalian tongues can be found in young dolphins but are few in number and limited to the thin epithelium of the pit projections and to that of the side wall of the pits. They first appear in the late prenatal period but degenerate in the adult. A rich nerve supply is observable in the lamina propria below taste buds in the calf. The pits and their projections in the dolphin correspond to the vallate papillae of other mammals, but whether each projection or a whole pit corresponds to a single vallate papilla is undecided.

Notizen: Two morphologically distinct structures occur on the surfaces of the oral papillae in several loricariid catfish species; namely, (1) typical vertebrate taste buds composed of receptor and sustentacular cells and (2) brushlike projections, termed epidermal brushes, that represent specialized epidermal cells containing keratin. Both of these structures were studied with the combined use of light microscopy and scanning and transmission electron microscopy. The general body surface, fins, and rostral cutaneous processes of some loricariid catfishes are covered with taste or terminal buds but lack the epidermal brushes. It is suggested that the epidermal brushes found on the oral papillae serve as protective devices for the taste buds and as abrasive surfaces for substrate scraping during feeding. The taste buds on the oral papillae may detect any gustatory stimuli from the resulting substrate disturbance. Comparative studies reveal many differences in the number and spatial arrangement of these two structures on the oral papillae among the several species of the Loricariidae examined. These differences may represent functional adaptations to the various modes of life in the Loricariidae.

Notizen: The Y-organ has been histologically identified in all six larval stages of the crab, Cancer anthonyi. The paired glands are located anterior to the branchial chamber and ventral to the base of the antennules. In the first zoeal stage the gland consists of a cord of 6 to 10 epidermal cells with dark staining nuclei, sparse cytoplasm, and indistinct cell boundaries. As development progresses the glands become more complex through extensive folding and intertwining of the cellular cords. The glands in all larval stages show cyclical activity which corresponds to the molt cycle. Immediately following a molt the gland is dense and compact with little cytoplasm. At approximately day four in the molt cycle, the glands become greatly hyperthropied due to an increase in the number and size of the cytoplasmic vacuoles. These histological changes suggests a cyclical production and presumably the release of some product most likely ecdysone.

Notizen: The digestive tract of a harpacticoid copepod, Tigriopus californicus (Baker), was studied by using techniques of light and electron microscopy. Four cell types could be distinguished: type 1, an embryonic cell which will replace cells worn away or lost during secretion; type 2, a cell which synthesizes and secretes proteins and also plays a role in lipid absorption; and types 3 and 4, two cell types which absorb lipids. From the abundance of each cell type, the length of microvilli, the development of basal plasma membrane (PM), and luminal projections, the following conclusions were made. (1) The midgut caecum absorbs digested nutrients. (2) The anterior midgut absorbs nutrients and more importantly functions in merocrine and exocrine secretion. The presence of concretions in cell types 2 and 3 in the anterior midgut suggests that these tissues contribute in excretion, and in water and/or ion regulation. (3) The posterior midgut absorbs nutrients and contributes some holocrine secretion.

Notizen: Tactile hairs are present on all three subsegments of the antennal flagellum of the human louse. There is, in addition, a single chemoreceptor (tuft organ) on subsegment 2 and 12 or 13 chemoreceptors (one tuft organ, two pore organs and nine or ten pegs) on subsegment 3. The cuticle surrounding the bases of the pegs at the tip of the antenna is unusual in that parts of it are perforated by many fine pores. This cuticle is underlain by a thin layer of dendrites. This region may also have a chemoreceptor function.

Notizen: The heart-body of the marine worm Amphitrite, located within the supraesophageal dorsal vessel, is in the form of a cylinder the thin wall of which is deeply corrugated by luminal projections and folds along its entire length. It is anchored in places to the luminal surface of the dorsal vessel by an extracellular matrix containing collagen fibers. The luminal surfaces of both the heart-body and the dorsal vessel are covered by a basement membrane-like vascular lamina which in turn supports a discontinuous pseudoendothelium of littoral hemocytes.The cells of the heart-body constitute a pseudostratified, high columnar epithelium. They possess extensive rough endoplasmic reticulum (RER), a well developed Golgi zone, ferritin particles and granules, and several types of membrane-bound inclusions. Hemoglobin molecules identical to those in the circulation lie within cytoplasmic, membrane-bound vesicles. Analysis of our electron micrographs suggests the following sequence of hemoglobin production and secretion: Large quantities of a moderately dense flocculent material, probably globin, are synthesized in RER and move to the Golgi zone within partly rough- and partly smooth-surfaced transitional cisternae; small transport vesicles, formed from Golgi cisternae that have fused with transitional cisternae, convey the flocculent material from the convex to the concave face of the Golgi complex; a similar flocculent material and an amorphous, highly dense material are processed in the Golgi complex and are transferred to condensing vacuoles in which clearly identifiable hemoglobin molecules are first observed. Mature secretory vesicles containing only hemoglobin migrate to the cell periphery and discharge their contents by exocytosis. Hemoglobin molecules then cross the vascular lamina to reach the circulation.

Notizen: The dermopteran basicranium combines a primitively constructed and oriented auditory bulla formed by ectotympanic, rostral entotympanic, and tubal cartilage with derived features of the middle ear transformer and internal carotid circulation. Living dermopterans possess a primitive eutherian auditory region that has been structurally modified to perceive a lower frequency sound spectrum than probably was utilized by ancestral Mesozoic therians. Perception of the low to midfrequency range is enhanced in Dermoptera by reducing stiffness in the mechanical transformer while maintaining low mass of the component parts. Stiffness has been reduced by (1) development of an epitympanic sinus about four times the volume of the middle ear cavity proper, (2) detachment of the anterior process of the malleus from the ectotympanic, and (3) by delicate suspension of the ear ossicles within the middle ear.We apply to dermopterans a measure of hearing efficiency derived from recent functional studies of the mammalian middle ear that regards the middle ear mechanism as an impedance matching transformer. Calculation of the impedance transformer ratio for Dermoptera suggests that these mammals are relatively efficient in comparison to other eutherians in their ability to match the impedance of cochlear fluids to that of air at the eardrum. Dermopterans theoretically are capable of using over 90% of incident sound energy striking the eardrum at the resonant or natural frequency. Mechanical impedance of the middle ear transformer exerts a minimal influence on hearing efficiency due to low mass, little stiffness, and little frictional resistance.Analysis of measurements of the middle ear transformer published by Gerald Fleischer and integration of these data with current theory on the peripheral hearing mechanism in mammals allow us to propose a model that describes the structural and functional evolution of the mammalian middle ear transformer. Structural changes appear to be correlated with alteration in function from primitive small mammals with stiff middle ear transformers and high frequency dominated hearing to mammals with a wider range in body size with more mobile middle ear transformers and a greater range of frequency perception, often including improved sensitivity to lower frequencies.Mammals employ different anatomical strategies in attainment of increased hearing efficiency and sensitivity. Efficiency is improved by adjustment of lever and areal ratios of the middle ear transformer to achieve an optimum impedance match of external air and cochlear fluids. Sensitivity over a broad frequency spectrum is attained by minimizing mass, stiffness, and frictional resistance of the transformer. The morphology of the auditory region of both living and fossil mammals seems explicable in terms of selection pressure directed toward these ends.

Notizen: Analysis based on telemetered electromyography from the quadriceps femoris of Lemur fulvus, a Malagasy prosimian, during walking, galloping, leaping, and a variety of postural behaviors partially confirms and partially contradicts earlier hypothesized functions of this musculoskeletal complex. As predicted on the basis of morphological criteria (large physiological cross-section and long parallel fibers), the vastus lateralis is of special functional significance in leaping. This relatively large muscle consistently initiates the leap and frequently undergoes a very long period of force enhancement via active stretch. By contrast, the vastus intermedius fails to exhibit increased electrical activity and undergoes little or no active stretch during jumps. The myological details of vastus intermedius (short fibers, no fusion with other components), therefore, cannot be accounted for as adaptations to leaping. Rather, a primary postural role is indicated for the vastus intermedius, because in normal resting postures, with the knee quite flexed, it alone is continuously active. The existence of a fibrocartilaginous superior patella in the tendon of vastus intermedius, however, is most plausibly related to the complex tensile and compressive stresses generated in the tendon during the completely hyperflexed phase of leaping.The phasic patterning of the quadriceps femoris of Lemur fulvus does not point to any special role of the vastus lateralis or vastus intermedius during walking and galloping; it does indicate very different patterns of muscle recruitment in comparison to those in nonprimate mammals and some anthropoid primates. The forward cross walk (diagonal sequence, diagonal couplets) of primates versus the backward cross gait (lateral sequence) of most other mammals probably accounts for some of these differences. Lemur fulvus lacks the degree of elastic storage and release of kinetic energy in the quadriceps femoris that characterizes the gallop of dogs, cats, and Erythrocebus patas.

Notizen: The active motility of the cells of the yolk sac of the living Fundulus embryo was studied by time-lapse cinemicrography with phase contrast optics. In the teleost, the yolk sac lies peripheral to the body of the embryo proper and consists of a fluid-filled space bounded above by a superficial epithelium, the enveloping layer (EVL), and below by the yolk syncytial layer (YSL). The cell types treated in the present study are the enveloping layer epithelial cell, the stellate cell which lies in a layer flattened on the inner surface of the EVL, the epithelioid deep cell, the yolk sac amoebocyte, the yolk sac endothelial cell and the yolk sac melanoblast. The most actively motile cells examined in the present study are the yolk sac amebocyte and the melanoblast, which emigrates from the embryo proper at stages 19-21. The amoebocytes are compact rounded cells that move very rapidly by the extension of lamellipods with scalloped margins. The amoebocytes wander over the yolk sac in an apparently undirected fashion and invade the embryo proper when they happen to encounter it, moving between cells of the lateral mesoderm. The melanoblasts migrate by the gradual extension of elongated branching processes. Cells are sometimes monopodial, with movement being parallel to the long axis of the cell. Alternatively, movement may be perpendicular to the predominant long axis, with processes being extended alternatively from opposite ends of the cell obliquely forward, so the path described is a zig-zag to either side of the overall direction of movement. Although the melanoblasts show irregularity in their movement, the predominant direction of initial movement is away from the embryo proper. The major yolk sac blood vessels form in situ by the collective activities of presumptive endothelial cells that enclose volumes of the yolk sac space with sheet-like processes from the cell body and from the extensions that connect cells into networks.

Notizen: Morphometric analysis of vertebral structure in caecilians (Amphibia: Gymnophiona) is presented. Ontogenetic variation in Dermophis mexicanus is analyzed through the 100+ vertebrae composing the column. Vertebral structure in adult D. mexicanus is compared with that in Ichthyophis glutinosus and Typhlonectes compressicauda. Centra of the atlas, second, tenth, 20th, and 50th vertebrae grow at allometrically different rates in D. mexicanus, though the 20th and 50th are not significantly different, Growth appears significantly slower in several dimensions of anterior and posterior vertebrae relative to midtrunk vertebrae in all three species. Mensural patterns throughout the entire column are similar in the terrestrial burrowers D. mexicanus and I. glutinosus; patterns in the aquatic T. compressicauda differ substantially from those of the burrowing species and are strongly influenced by allometry. Of the 112 D. mexicanus examined, 13.4% had vertebral anomalies, usually fusions.

Notizen: Statoblasts of five higher phylactolaemates were compared morphologically. As a result, they were divided into two groups: Group I comprising Lophopus crystallinus, Lophopodella carteri, and Pectinatella gelatinosa, and Group II comprising Pectinatella magnifica and Cristatella mucedo. These two groups are thought to represent independent evolutionary series. In Group I and in P. magnifica, the statoblasts are curved to varying degrees after the manner of a saddle. When the dorsal and ventral valves are flattened, therefore, the contour is different between the two. In Group I, the outermost layer of a mature statoblast is hard-gelatinous and basophilic; it remains intact after the statoblast is set free. The statoblast does not float until it is dry, and the float is similar in size on both valves. In Group II, a mature statoblast is covered by a softgelatinous basophilic layer, which decays after the statoblast is released. The statoblast floats without drying, and the float is better developed on the dorsal valve than on the ventral. Moreover, in the members of Group II, large yolk granules are first formed, followed by much smaller yolk granules. When their statoblasts are treated with KOH, the shell is separated completely into two valves. These characters are common to many lower phylactolaemates. By contrast, in L. carteri and P. gelatinosa, the yolk granules are uniformly small and the capsule proper resists KOH treatment. On these points, L. crystallinus is somewhat different from these two species, suggesting its primitive nature.

Notizen: Teeth of fetuses of a caecilian, Dermophis mexicanus (Amphibia: Gymnophiona), show ontogenetic variation in crown structure from small, multidenticulate, and non-pedicellate to larger, spoon-shaped, pedicellate teeth with a single apical spike. Number of denticles decreases as enamel-secreting cells mature. Numbers of teeth and of tooth rows increase ontogenetically. A fetal vomeropalatine set of teeth is present in D. mexicanus but absent in species previously examined. Teeth transitional to the adult shape and arrangement appear shortly before birth. The transition is correlated with birth, not fetal size. There is relatively little increase in numbers of teeth during the juvenile period. The pattern of development does not fully agree with either morphogenetic field theory or with clone theory, both as defined by Osborn ('78). Sequence of initiation is appropriate to either. Tooth shape changes agree with aspects of clone theory. Multiple rows of fetal teeth and the transition to adult follow field theory. Clone theory holds that patterns of development and shape are self-regulated, field theory that they are controlled extrinsically. I suggest that substances regulating differentiation mediate early development, and hormones later development, including inception of adult teeth, and are comparable to “field substances” influencing primordia that originate according to clone theory. Components of both theories are appropriate to analyzing tooth development phenomena.

Notizen: Previously unreported structures found on the head and thorax of several species of microcaddisflies (Trichoptera: Hydroptilidae) are described. Depending on the species, these presumptive pheromone-producing glands are found either (1) on the basal segment of the antenna, (2) on movable and immovable occipital sclerites, (3) as eversible organs from the occipital area of the head, or (4) on structures which are attached near the bases of the front wings.

Notizen: The morphology and organization of chromatophores in the neotropical glass-frog, Centrolenella fleischmanni (family Centrolenidae), were studied with both light and electron microscopes. Four types of pigment cells are described in the dorsal skin. The fine structure of two chromatophores corresponds to the typical amphibian xanthophore and iridophore; one is similar to the unusual melanophore found in phyllomedusine hylids; the fourth cell type is unlike any chromatophore previously described. Pigment granules in the unusual chromatophore are moderately electron-dense and have an irregular shape, suggesting a fluid composition. This pigment appears to be laid down in organelles similar in appearance to pterinosomes. The organization of pigment cells in this species differs from that of other green, leaf-sitting frogs in that there are few discrete groups resembling “dermal chromatophore units.” It is suggested that the unusual new pigment cell contributes significantly to the overall green color of C. fleischmanni.

Notizen: Electron microscopy of the cerebral ganglionic commissure of the leech Macrobdella decora (Say, 1824) revealed numerous neurosecretory axons terminating in the neural lamella of both the inner and outer capsules, and in the neural lamella deep within the neuropile. The proximal protions of the terminals, with an investment of glial tissue, contain either numerous large homogeneously electron dense granules, or numerous large granules of varying electron density. The distal portions, often devoid of glia, display numerous infoldings, omega profiles, and electron dense focal sites, and contain numerous neurosecretory granules, small lucent vesicles, and, occasionally, acanthosomes. Statistical analysis of the size distribution and morphology of the neurosecretory granules showed that in many individual terminals the granules are not significantly different from those seen within four groups of neurosecretory cells found in the cerebral ganglion. These terminals, because of their diffuse nature, probably represent a neurohemal complex of a primitive nature. The term “intralamellar complexes” is proposed to describe the form and location of these neurosecretory terminals.

Notizen: Rat submandibular gland was dissociated by enzymatic digestion with collagenase and hyaluronidase, followed by mild mechanical shearing and filtration through a nylon mesh. The dissociated cell populations contained predominantly groups of acinar cells which maintained their acinar arrangement. The morphological and functional viability of the cells was confirmed by electron microscopic examination and a normal secretory response to β-adrenergic or cholinergic stimulation was observed. Both isoproterenol (IPR) and carbachol caused the fusion of secretory granules into large vacuoles which were also continuous with the lumen, and into which the secretory product was released. Secretion was assessed quantitatively from the incorporation of 14C-glucosamine into the acinar cells and its subsequent release into the culture medium as labelled glycoprotein. IPR stimulated secretion to 125% of untreated controls in the concentration range 5 × 10-5 to 5 × 10-7 M, and to 110% of controls at 5 × 10-8 M, after 40 min incubation. Carbachol stimulated secretion to 131% of controls at 5 × 10-5 M and to 115% at 5 × 10-6 M but had no effect at 5 × 10-7 or 5 × 10-8 M. The secretory response was blocked by the respective β-adrenergic and cholinergic antagonists, propranolol and atropine. These findings show that dissociated rat submandibular acinar cells provide a useful in vitro model for the study of mucus synthesis and secretion.

Notizen: The cupula of the supraorbital neuromast in the lateral line canal of the clown knifefish contains vertical columns. In the central region of the cupula overlying the macula, these columns are densely packed, are relatively constant in size, and run from the base of the cupula to the surface of the cupula which is exposed to canal fluid. There are two types of columns, dark and light, which form elliptical compartments in planes of section that cut across the columns; the cupula therefore has the appearance of mosaic tile in such sections. The dark compartments contain tubules that extend from the base of the cupula at the junction with the macula to the top of the cupula. Each tubule is associated with the kinocilium of a single hair cell. The lateral parts of the cupula, not overlying the macula, also contain compartments, but these compartments differ in size and structure from those in the central region. In addition to the compartments, the central region of the cupula also contains spherical aggregates of droplets. These small aggregates, termed mora, are found principally in a layer within the central region of the cupula, but are also found outside this layer. Because of their light-reflecting properties, the mora can be used for noninvasive optical measurements in vivo of the motion of the cupula.

Notizen: 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.

Notizen: The paired organ of Bellonci protrudes from the optic lobe of the giant Antarctic isopod, Glyptonotus antarcticus. It is linked to the cortex by a broad peduncle. No connection to the cuticle or “sensory pore organ” was found. A cluster of sensory-like cells forms two outer ciliary segments branching into numerous microvilli with microtubules. The putative sensory somata are irregular in shape and contain a very high density of glycogen granules. The two outer segments sprout from two pits of the soma in different directions, forming a right angle. Glial cells wrap around the sensory cells and also delimit lacunae into which bundles of microvilli project. These lacunae contain electron-dense granules of small size and with species-specific patterns. Lacunae and dense granules show features typical of a degeneration process in the sensory cells.This general morphology corresponds to the unilobular type of organ of Bellonci, known in other isopods; it differs from the plurilobular type with onion bodies found in other Crustacea.

Notizen: Neuromast structure in Rana cancrivora larvae was observed by scanning and transmission electron microscopy. Neuromast units, each being composed of two or three neuromasts, are arranged in several well-defined lines in the head, body, and tail regions. The structure of neuromasts in these three regions is basically identical. The neuromast is composed of sensory, sustentacular, and mantle cells. The top of each neuromast has a hillocklike appearance, and is surrounded by four to six epidermal cells with tight intercellular junctions. Long kinocilia and many stereocilia occur in the apex of the neuromasts and are surrounded by numerous microvilli. Numerous granules are present on the apical portions of the mantle and the sustentacular cells. Four or five trapeziform mantle cells are connected closely with each other to form the shell of the neuromast. Large intercellular spaces occur between the mantle cells and the cells of the inner epidermal layers, and between the cells of the inner epidermal layer. Thus, at the apical parts of the neuromast intercellular junctions are tight and the intercellular spaces are more dilated in more basal areas. Morphologically the neuromasts of R. cancrivora larvae resemble those of generalized pond anurans, based on the grouping of Lannoo (Journal of Morphology 191:115-129, 1987a), although larvae of this species inhabit brackish water.

Notizen: 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.

Notizen: The muscle fibers of the feline biceps femoris have tapered ends, across which tension is transmitted to the endomysium. The angle of taper of 11 ends, measured on scanning electron micrographs, varied between 0.16° and 1.18°. The muscle fibers are highly variable in cross-sectional shape. The shape of the fibers has been quantified as the ratio (form factor [FF]) of the measured perimeter to the calculated circumference of a circle having an area equal to that contained by the fiber perimeter. The FF for 173 terminal portions of fibers varied between 1.06 and 1.85 and was found to have a highly significant negative correlation with sarcomere length. The slope of the regression line suggests that the fibers maintain both volume and surface area as they change length. These studies suggest that isovolumic muscle fibers maintain a constant surface area by changing shape as they change length.

Notizen: Salt glands of the domestic duck Anas platyrhynchos differ from those of the herring gull Larus argentatus and other birds. In ducks, each salt gland consists of distinct medial and lateral segments. Centrally located drainage ducts that extend along the entire length of these medial and lateral segments collect hypertonic fluid secreted by an array of lobules. Each lobule is formed by a single mass of branched tubules in which the direction of capillary blood flow is opposite to that of the secreted fluid. This fluid drains from the medial segment through an external duct that opens into the nasal cavity at the base of the vestibular fold. A duct from the lateral segment loops and opens onto the surface of the nasal septum. The structure and function of the secretory cells is reviewed briefly within the context of our study of the configuration of duck nasal salt glands.

Notizen: A contrast radiographic study of pelvic fin drainage in rays reveals considerable differences in patterns of drainage among the species studied. The “typical” shark pattern of drainage, to the lateral abdominal vein, is also found in rays with shark-like morphology. However, variation in the connections of pelvic fin veins to muscular and cutaneous vessels of the pectoral fin occurs in the more “derived” batoid groups, with marked differences between rays of similar external morphology and mode of locomotion. There is a positive association between the pattern of fin drainage and the number of radial cartilages in the posterior (metapterygial) lobe of the pectoral fin. Variation in shark pelvic fin drainage may also be related to differences in pectoral fin morphology.

Notizen: Dissections of Sudan black B stained specimens reveal that, of a complex of medial, intermediate, and lateral muscles of skates, presumed homologous to the cucullaris of sharks, only the lateral muscle is innervated by a branch or branches of the vagus and is inserted, in part, to the fused pharyngobranchials of the caudal visceral arches. The medial and intermediate muscles are supplied by separate branches of rostral spinal nerves and do not attach to the branchial skeleton. The lateral muscle therefore is the most likely homologue of the cucullaris (trapezius) of sharks and perhaps other fishes and tetrapods. The medial and intermediate muscles appear to be part of the axial musculature.

Notizen: An immunocytological study of four different parts of the gut of Helix aspersa clearly demonstrates the presence of many cells and fibers immunoreactive toward antibodies directed to vertebrate (α, β-endorphin, α, β-MSH, ACTH 1-24 and ACTH 17-39, met-enkephalin, somatostatin, insulin, glucagon, P.P., serotonin) or invertebrate (FMRF-amide) peptides.These results are evidence of the presence of different substances related to known peptides or amines in the epithelial and connective tissue cells and nerve fibers of the snail gut. Immunocytochemistry may help to elucidate the morpho-functional characteristics of the enteroendocrine cells of H. aspersa.

Notizen: A histochemical investigation of kidney and lower intestine of the European starling (Sturnus vulgaris) shows no carbonic anhydrase activity in proximal convoluted tubules, although activity is seen in similarly prepared sections of rat proximal tubules. Early distal tubule cells in the starling are stained throughout the cytoplasm and at the apical and highly infolded basolateral membranes. Late distal tubules lose apical activity and have reduced basolateral infolding, resulting in less intense staining. Darkly stained intercalated cells appear in the connecting tubules and cortical collecting ducts. Both of these segments also show intense basolateral staining. Medullary cones of the starling are highly organized, with central zones containing unstained thin descending limbs of loops of Henle, surrounded by both medullary collecting ducts with only scattered cells staining for enzyme, and by thick ascending limb segments. The latter contain many uniformly stained cells intermingled with occasional unstained cells. Scattered cells of the starling colonic villi demonstrate intense apical brush border membrane staining as well as cytoplasmic staining. Cells lining the cloaca stain less intensely. A biochemical assay for carbonic anhydrase was used to quantify enzyme activity in these tissues. Starling kidney contained 1.96 ± 0.33 (mean ± SEM) enzyme units/mg protein, less than half the activity seen in rat kidney. Stripped colonic epithelium contained 0.66 ± 0.15 enzyme units/mg protein. These quantitative results correlate well with the interpretations derived from the histochemical observations. The lack of proximal tubule carbonic anhydrase activity suggests that the avian kidney relies more on distal nephron segments to achieve net acidification of the urine.

Notizen: 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.

Notizen: In the first half of this century, several workers observed small, seemingly glandular structures attached to the ampullate glands of spiders. Hence, they were termed accessory ampullate glands. In juvenile Araneus cavaticus, two pairs of these structures are present (starting at least with third instars), one pair attached to the major ampullate (MaA) glands and the other pair attached to the minor ampullate (MiA) glands. In adults, two pairs of accessory MaA glands and two pairs of accessory MiA glands are present. The two latter-formed pairs of accessory ampullate glands are clearly the remnants of those ampullate glands which atrophy shortly after adulthood is reached. Morphological similarities between these accessory ampullate glands and those present in juveniles provide an indication that the latter also have their origin in functional ampullate glands.A reduction in the number of ampullate glands following the last molt occurs in many spiders. The reason(s) for these reductions is unknown. In penultimate spiders close to ecdysis, we have observed that while the larger pairs of MaA and MiA glands (those that are retained in the adult) are undergoing molt-related changes which apparently render them nonfunctional, their smaller counterparts are seemingly unaffected and functional. This raises the possibility that the principal role of the smaller ampullate glands may be to assume functions during the pre-ecdysial period which are normally in the domain of the larger ampullate glands. If true, then their degeneration after the last molt would make economic sense.The presence of cylindrical spigots in juvenile females starting with fourth instars is documented.

Notizen: Three basic types of cells are distinguished in the rat vomeronasal epithelium at birth: bipolar neurons, supporting cells, and basal cells. Neurons at this time include both immature and differentiated cells. By the end of the first postnatal week, all neurons show morphological signs of maturity in their cytoplasm, including abundant granular and smooth endoplasmic reticulum, neurotubules, dense lamellar bodies, apical centrioles, and tufts of microvilli. During the third week microvilli are more frequently encountered and appear to be longer and more branched. Supporting cells appear well-developed by the second day after birth. During the first ten days of life, supporting cells lose their centrioles and all of the complex associated with ciliary generation in the apical zone. Basal cells appear to be more numerous in newborns than in older animals. Protrusions projecting into the lumen are frequently observed in the epithelium of newborn animals, both on the dendrites of neurons and on supporting cells. After the third week, such protrusions are only observed in the transitional zone between the sensory and the non-sensory epithelia of the vomeronasal tubes. In this transitional zone, a fourth cell type showing apical protrusions with microvilli differentiates. Cytoplasm in this type resembles that of neighboring ciliated cells but has no cilia or centrioles. These transitional cells are considered to be cells in an intermediate state of differentiation, between that of the differentiated neurons and supporting cells of the sensory epithelium and that of the predominate ciliated cells of the non-sensory epithelium. The results suggest that by the end of the third week the vomeronasal epithelium is morphologically mature.

Notizen: The wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1-5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.

Notizen: Previous studies by Stephens and McNulty and Strecker and Stephens have demonstrated that foil barriers placed between the mesonephros and lateral plate at stages 12 to 15 inhibited limb development, but foil barriers placed between the neural tube and somites at stages 11 to 12 resulted in limbs with normal skeletal patterns. It was concluded that some influence present in the paraxial region of the embryo at stages 11 to 15 is necessary for normal limb development. The present study was undertaken to localize that influence more precisely. Foil barriers were placed in the lateral edge of the somites or segmental plate of stage 10 to 15 chick embryos. Barriers placed into stage 13 to 15 embryos resulted in chicks with normal limbs, but barriers placed into stage 10 to 11 embryos resulted in chicks with defective limbs. Barriers inserted just lateral to Hensen's node at stages 6 to 8 resulted in embryos with defective or absent wings. We also grafted stage 4 to 9 presumptive limb territories with and without Hensen's node. Explants without Hensen's node formed limb-like structures in 1% of the cases. Explants with Hensen's node formed limb-like structures in 27% of the cases. When barriers were implanted and a node was placed on the lateral side of the barrier, limbs formed in 40% of the cases. These data suggest a medial to lateral progression of some as yet unknown morphogenetic influence necessary for normal limb development and we hypothesized that the influence may initially emanate from Hensen's node.

Notizen: The limb bone skeleton of the moa, a family of extinct ratite birds endemic to New Zealand, is described with particular reference to the anatomical and functional significance of osteological landmark form variation. The results generally support the existing classification of moa. Four genera, Megalapteryx, Anomalopteryx, Dinornis, and Pachyornis, were found to be evolved within moa, with Emeus and Euryapteryx possibly being more primitive. Megalapteryx was found to be less mobile than other moa genera. The Dinornis species were found to be more cursorial and more mobile relative to other moa. They may also have had a different center of gravity. A marked development of the lower leg in Anomalopteryx suggested a digging habit associated with food procurement.

Notizen: A detailed description of muscular and skeletal features of the pelvi-cloacal region of the amphisbaenian Blanus cinereus reveals that the species has real hind limbs articulating with a real pelvic girdle. Arguments support this homology: 1) a link with the vertebral column; 2) a movable articulation, showing all the features of a diarthrosis, between the femur and the acetabulum; 3) all the long bone characteristics for the femur which distally bears a horny element. The morphological peculiarities of the amphisbaenian pelvic girdle are generally close to those of lizards, but the pubis seems to be more reduced. For the same number of precloacal vertebrae, the amphisbaenians have more appendicular elements than lizards have, and this composition recalls that of the Leptotyphlopidae, Aniliidae, and Boidae. The account provides more information concerning the aponeuro-tendinous system associated to the skeleton of the girdle and the hindlimb, the musculature, and the interrelations between the different structures of the pelvi-cloacal region.

Notizen: Programmed cell death is an integral and ubiquitous phenomenon of development that is responsible for the reduction of wing size in female moths of Orgyia leucostigma (Lymantriidae). Throughout larval and pupal life, cells of the wing epithelium proliferate and interact to form normal imaginal discs and pupal wings in both sexes. But at the onset of adult development, most cells in female O. leucostigma wings degenerate over a brief, 2-day period. Lysosomes and autophagic vacuoles appear in cells of the wing epithelium shortly after it retracts from the pupal cuticle. Hemocytes actively participate in removing the resulting cellular debris. By contrast, epithelial cells in wings of developing adult males of O. leucostigma do not undergo massive cell death. Wing epithelium of female pupae transferred to male pupal hosts behaves autonomously in this foreign environment. By pupation, cells of the female wing apparently are committed to self-destruct even in a male pupal environment. Normal interactions among epithelial cells within the plane of a wing monolayer as well as between the upper and lower monolayers of the wing are disrupted in female O. leucostigma by massive cell degeneration. Despite this disruption, the remaining cells of the wing contribute to the formation of a diminutive, but reasonably proportioned, adult wing with scales and veins.

Notizen: We describe the localization of lipids in the wall and superficial ooplasm of the largest avian ovarian follicles by the use of different fixatives and light and electron microscopy. We demonstrate that each yolk globule is always accompanied by one or more highly osmiophilic and sudanophilic alcohol insoluble yolk masses, which we have called satellite yolk. Together with the protein containing yolk globule it forms an integral morphological part of a compartmentalized, bipartite yolk system. Cytochemical, histoautoradiographic, biochemical, and light and electron microscopical aspects of satellite yolk were studied. At the start of satellite yolk formation in the 3-4 mm diameter follicle (when the oocyte begins to yellow) the distribution of the microcirculation of the follicle wall becomes printed on the underlying superficial ooplasm of the oocyte. The oocyte then presents so-called yolk mountains (containing satellite yolk), only localized below the thecal capillary sinus and not below the efferent and radially perforating thecal veins (black hole regions). We also describe the structural continuity between the thecal intercellular spaces and the microvilli-associated extracellular spaces of the granulosa cells via the basement membrane. The thecal cells present centripetal extensions into the basement membrane and the basement membrane material extends centripetally into the granulosa microvillar channels. Therefore, at least two cellular barriers are crossed when fat or fat precursors are transported from the thecal capillary sinus to the ooplasm.

Notizen: Embryos of the poeciliid Heterandria formosa develop to term in the ovarian follicle in which they establish a placental association with the follicle wall (follicular placenta) and undergo a 3,900% increase in embryonic dry weight. This study does not confirm the belief that the embryonic component of the follicular placenta is formed only by the surfaces of the pericardial and yolk sacs; early in development the entire embryonic surface functions in absorption. The pericardial sac expands to form a hood-like structure that covers the head of the embryo and together with the yolk sac is extensively vascularized by a portal plexus derived from the vitelline circulation. The hood-like pericardial sac is considered to be a pericardial amnion-serosa. Scanning and transmission electron microscopy reveal that during the early and middle phases of development (Tavolga's stages 10-18 for Xiphophorus maculatus) the entire embryo is covered by a bilaminar epithelium whose apical surface is characterized by numerous, elongate microvilli and coated pits and vesicles. Electron-lucent vesicles in the apical cytoplasm appear to be endosomes while a heterogeneous group of dense-staining vesicles display many features characteristic of lysosomes. As in the larvae of other teleosts, cells resembling chloride cells are also present in the surface epithelium. Endothelial cells of the portal plexus lie directly beneath the surface epithelium of the pericardial and yolk sacs and possess numerous transcytotic vesicles. The microvillous surface epithelium becomes restricted to the pericardial and yolk sacs late in development when elsewhere on the embryo the non-absorptive epidermis differentiates. We postulate that before the definitive epidermis differentiates, the entire embryonic surface constitutes the embryonic component of the follicular placenta. The absorptive surface epithelium appears to be the principle embryonic adaptation for maternal-embryonic nutrient uptake in H. formosa, suggesting that a change in the normal differentiation of the surface epithelium was of primary importance to the acquisition of matrotrophy in this species. In other species of viviparous poeciliid fishes in which there is little or no transfer of maternal nutrients, the embryonic surface epithelium is of the non-absorptive type.

Notizen: The flagellum of the thysanopteran spermatozoon has been examined by electron microscopy and computer-aided image analysis. The flagellum consists of 27 microtubular elements that probably are formed as outgrowths from three separate basal bodies. Nine of the elements are normal microtubular doublets that carry dynein arms and nine are doublets without dynein arms. The remaining nine elements are microtubular singlets that apparently bear dynein arms and have the same appearance as A-subtubules of microtubular doublets. The 27 elements are arranged in a fixed pattern that consists of nine groups, each of which begins with a microtubular singlet and ends with an arm-less microtubular doublet. Computer-aided image analysis has shown that the A-subtubules of the doublets and the microtubular singlets have lumens with very similar patterns. The sperm tail is known to have some motility; it generates fast waves running along its length. The amalgamated axonemes hence act as a functional flagellum. The thysanopteran sperm tail is the only type of flagellum known to us that consists of microtubules in a highly asymmetric array.

Notizen: Many arachnids lack extensor muscles at the femoropatellar (knee) joint of their legs and extend this joint with hydraulic pressure during locomotion. Pressure is generated through compression of the prosoma, but there is disagreement about which muscles are involved in this process. Many arachhnologists consider contraction of the musculi laterales, a group of modified extrinsic leg muscles, as the cause of high prosomal pressure and regard hydraulic extension as a derived feature. However, integration of results from phylogenetic and comparative anatomical studies supports the view that hydraulic extension is primitive in Arachnida and that fluid pressure is generated by contraction of endosternal suspensor muscles.The functional predictions of the musculi laterales and endosternite hypotheses were tested by measuring muscle activity and prosomal pressure during unrestrained locomotion in a primitively “extensorless” arachnid, the giant whipscorpion. The results corroborate the endosternite model and refute the musculi laterales model. Changes in the prosomal pressure baseline were correlated with changes in endosternal muscle activity, while the musculi laterales fired in a step-coupled pattern of discrete bursts that appeared to be incapable of generating the pressure observed during locomotion. Step-coupled fluctuations in prosomal pressure were observed but were apparently caused by rapid flexing of the femoropatellar joints of the fourth leg pair rather than contraction of the musculi laterales.

Notizen: In the fungiform papilla of Rana esculenta (Anura Ranidae), the Ca++-ATPase is mainly distributed on the basolateral membrane of the sensory area cells (i.e., neuroepithelial, supporting, and mucous cells). Apical membranes of all cells facing the surface present a slight enzymatic activity. Lateral wall cells have a strong Ca++-ATPase activity on basolateral and apical membranes. Strong Na+, K+-ATPase activity occurs on the apical surface of neuroepithelial cells. Ca++-ATPase activity is absent on the surface of endothelial cells of the capillaries located under the sensory area. These observations lead us to conclude that the sensory area of fungiform papilla is the selective way for calcium influx. Furthermore the absence of ATPase activity on the surface of the endothelial cells indicates that there is no functional barrier to calcium influx into capillary, and that calcium can be removed by vessels from the sensory area.

Notizen: 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).

Notizen: The morphology and distribution of muscle spindles of jaw and tongue muscles in the mallard were examined in serial transverse sections of single muscles and in horizontal sections of a whole head. Our observations on spindle morphology are in agreement with previous descriptions of spindles in birds. Some spindles differ in their innervation and the pattern of intrafusal muscle fibers. The spindles of individual adductor and pterygoid muscles are distributed unevenly. Some adductor muscles lack spindles, whereas those of other muscles are confined to limited areas. Jaw opening muscles and extrinsic tongue muscles lack spindles. The stretch of extrafusal muscle fibers could be estimated from the difference in sarcomere length for birds with the beak open and closed. Not all muscle fiber groups are stretched evenly over the whole range of jaw opening. Only those fiber groups that are continuously stretched during jaw opening contain spindles.

Notizen: Living embryos of three species of South American annual fishes, Cynolebias constanciae, C. nigripinnis, and C. whitei, were observed from fertilization through the 10-somite stage. A description of normal stages of development applicable to all three species of Cynolebias is presented. Cleavage (stages 1-10) is meroblastic and produces a typical teleost blastoderm. Following cleavage (stages 11-13) blastomeres segregate into two populations, viz., (1) a population of deep blastomeres that will disperse as single motile cells, and (2) a hemispherical shell of outer blastomeres that flattens to form an enveloping cell layer (EVL). When epiboly of the EVL and the yolk syncytial layer (YSL) commences (stage 14), deep blastomeres clump together as a consolidation mass and then migrate outward as single cells on the YSL. When epiboly is concluded (stage 19), deep blastomeres have completely dispersed. If diapause does not intervene, the dispersed phase lasts only a few days. Subsequently, the dispersed cells come together to form a definitive aggregate (stage 27). Embryogenesis within the reaggregated mass of previously dispersed cells produces a typical teleost embryo.Early development in Cynolebias resembles that of other South American annual fishes, such as Austrofundulus, in that a phase of deep blastomere dispersion and reaggregation spatially and temporally separates epiboly from embryogenesis. Several features of development markedly differ from Austrofundulus. There are far fewer (250 vs. 2,500) deep blastomeres. Deep cells of Cynolebias are flattened rhomboids with filipodial extensions in contrast to the amoeboid cells of Austrofundulus. Blastomeres of dispersion and reaggregation stages in Cynolebias send out numerous cell surface extensions onto the YSL and in contact with one another, and often line up in rows as do some African annual fishes, e.g., Nothobranchius. During Dispersion II (stage 21), Reaggregation I (stage 22), and Reaggregation II (stage 23), deep cells move in an oriented pattern with respective mean velocities of 3.48 ± 0.91, 1.28 ± 0.46, and 1.31 ± 0.31 μm/minute. Cells move toward a granular mass of unknown composition, located at the YSL-yolk interface in the lower hemisphere of the egg. This mass appears to coincide with the site of cell reaggregation.

Notizen: Several surfperches (Embiotocidae), including the black surfperch, Embiotoca jacksoni, exhibit a specialized prey handling behavior known as winnowing, in which ingested food and non-nutritive debris are separated within the oropharyngeal cavity. Prey items are swallowed, and unpalatable material is ejected from the mouth. Winnowing is believed to play an important role in the partitioning of food resources among sympatric embiotocids. We present a mechanistic model for this separative prey processing based on high-speed video analysis, cineradiography, electromyography, and buccal and opercular cavity pressure transducer recording.Winnowing by embiotocids is characterized by premaxillary protrusions repeated cyclically with reduced oral gape. Protrusion is accompanied by depression of the hyoid apparatus and adduction of the opercula. Alternating expansion and contraction of the buccal and opercular cavities generate regular pressure waveforms that indicate bidirectional water flow during processing. Separation of food from debris by Embiotoca jacksoni occurs in three phases. The prey-debris bolus is transported anteriorly and posteriorly within the oropharyngeal cavity and is then sheared by the pharyngeal jaws. Mechanical processing is complemented by the rinsing action of water currents during hydraulic prey transport.The feeding apparatus of Embiotoca jacksoni is functionally versatile, although not obviously specialized relative to that of nonwinnowing surfperches. Protrusion of the premaxillae and depression of the hyoid apparatus are critical to both prey capture and subsequent prey processing. The pharyngeal jaws exhibit kinematic patterns during separation of food from debris distinct from those observed during mastication of uncontaminated prey. This behavioral flexibility facilitates resource partitioning and the coexistence of E. jacksoni in sympatric embiotocid assemblages.

Notizen: Quantifying shape is a broad problem in the morphological sciences. Most techniques for numerically describing shape abstract the shape into the most logical ideal Euclidean dimension. The fractional, or fractal, dimension is a simple computation that expresses shape in real, rather than ideal, space. The structured walk technique developed for the fractal analysis of rugged boundaries is applied here to the contour of the human sagittal suture in order to discriminate the separate morphological patterns of interfingering and interlocking. These attributes contribute differentially to the suture's “complexity,” a concept often used in biomechanical hypotheses. Previous techniques for estimating sutural complexity do not isolate small-scale from large-scale morphological patterns. Results indicate that despite the visual appearance of great variation, human sagittal sutures are remarkably consistent in the degree of complexity expressed separately by large-scale interfingering lateral excursions and small-scale interlocking ruggedness. There is no significant correlation between the absolute or bregma-lambda chord length of the human sagittal suture and its degree of complexity as determined by the structured walk technique.

Notizen: 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.

Notizen: Spermiogenesis in the South American leptodactylid frog Odontophrynus cultripes was analyzed ultrastructurally. The spermatids undergo morphological modification while still enclosed in microtubule-rich processes of Sertoli cells. Electron-dense plates resembling junctional structures appear in regions at which the spermatids lie in close contact with the surface of Sertoli cell processes. Spermatid differentiation can be divided into five distinct stages based mainly on chromatin condensation. In the late stages, the densely compacted chromatin loses reactivity to ethanolic phosphotungstic acid (E-PTA). Helical arrangements of microtubules appear in the cytoplasm that surrounds the spermatid nucleus after the second stage. The acrosomal vesicle differentiates into a cone-shaped acrosome that caps the anterior region of the nucleus. The connecting piece, located in the flagellum implantation zone, has transverse striations, and is continuous with the axial rod. The tail is formed by a 9 + 2 axoneme, an undulating membrane, and an axial rod that is rich in basic proteins as demonstrated by E-PTA staining.

Notizen: Morphology of the chromaffin cells of Triturus cristatus during a complete annual cycle has been investigated. General ultrastructural characteristics are similar for all chromaffin cells, including numerous small mitochondria, well-developed Golgi apparatus and rough endoplasmic reticulum with short cisternae. The primary difference among cells is the type of the chromaffin granules they posses. These are of two kinds: adrenalin (A) and noradrenalin granules (NA). Both types are simultaneously present in the chromaffin cells but with different ratios during the year. During December-January and May-August, NA granules largely prevail, while in September-November and February-April, A and NA granules are present in about equal quantities. The total quantity of catecholamine granules, however, is relatively constant throughout the year. These findings suggest that T. cristatus has a single type of chromaffin cell, the granule content of which varies according to different functional states. The catecholamines are apparently discharged by exocytosis.

Notizen: The palatoquadrate and associated dermal bones have significant evolutionary transformations among teleostomes and provide numerous features that characterize teleostomian subgroups. The palatoquadrate forms the upper part of the mandibular arch and is present as a single cartilaginous element in the early ontogeny of teleostomes, except for some advanced teleosts such as siluroids where it is divided into pars autopalatina and pars pterygoquadrata. During ontogeny, the palatoquadrate may ossify as a unit, with a pars autopalatina (absent in Acanthodii), pars quadrata, and pars metapterygoidea in teleostomes (e.g., primitive acanthodians and actinopterygians, onychodonts, and rhipidistians). However, the palatoquadrate may remain cartilaginous (e.g., chondrosteans) or it may ossify as separate elements (e.g., autopalatine, metapterygoid, and quadrate) as occurs in advanced acanthodians, Polypterus and advanced actinopterygians, and advanced actinistians. From the single-unit pattern, separate autopalatine, metapterygoid, and quadrate evolve in parallel in the three teleostomian subgroups. Therefore, it is necessary to distinguish between actinopterygian and actinistian autopalatines and among acanthodian, actinopterygian, and actinistian metapterygoids and quadrates. A palatoquadrate fused with the neurocranium occurs in parallel in dipnoans.There are differences in the timing of ossification of the autopalatine, metapterygoid, and quadrate. The autopalatine ossifies late in ontogeny in Polypterus, Amia, and primitive teleosts (absent in lepisosteids and osteoglossmorphs), whereas both metapterygoid and quadrate ossify early in ontogeny. The early ossification of the autopalatine is characteristic of clupeocephalan teleosts. During ontogeny, tooth plates (not forming a separate dermometapterygoid) fuse with the metapterygoid in actinopterygians.Pars autopalatina, pars metapterygoidea, and pars quadrata are regions at the three corners of the single-unit palatoquadrate present in primitive teleostomes; there are no clear limits among these regions, but they may be identified by their processes, articular facets, and topographical relationships with surrounding bones and the orbit. Autopalatine, metapterygoid, and quadrate are chondral bones, perichondrally ossified. Dermal elements such as dermopalatine(s), entopterygoid, ectopterygoid, and tooth plates may cover the palatoquadrate medially. The predermopalatine that originates in front of pars autopalatina in Cladistia and the “dermopalatine” that lies medial to the ectopterygoid in Ginglymodi are specializations of these groups. A dermopalatine fused with the autopalatine is characteristic of clupeocephalan teleosts. Highly specialized tendon bone pterygoids are found in some teleosts (e.g., siluroids). The presence of both maxilla and lacrimal lateral to the pars autopalatina is synapomorphous of osteichthyans. The eye supported by the bony palatoquadrate is a teleostomian synapomorphy. Dermal elements support the eye in actinopterygians, the entopterygoid in advanced actinopterygians, but the ectopterygoid in lepisosteids.A quadratojugal is a synapomorphy of osteichthyans but exhibits a number of transformations in connection with the vertical pit-line and the preopercular canal; a quadratojugal bearing the vertical pit-line is the primitive condition for osteichthyans. Ontogenetic evidence does not support the homology of the membranous posterior process of the teleostean quadrate with the quadratojugal. The lack of a quadratojugal and the presence of the elongate posterior or posteroventral process of the quadrate is a synapomorphy of teleosts.

Notizen: The presence of scolopophorous organs in aquatic Heteroptera has been reported in a number of species. This study presents a morphological investigation of these sensory structures of Lethocerus (Belostomatidae) as observed with the scanning electron microscope (SEM). Paired mesothoracic and metathoracic organs are present. Externally, each sensory structure consists of a raised sensory membrane. The distal-most portion consists of thickenings of this sensory membrane (sclerite). The receptor neurons of the mesothoracic organ are of two types - one discolopidial sensillum and 12 monoscolopidial sensilla. The former is attached to the internal wall and distal thickening of the sensory membrane, while the latter are dispersed throughout the interior and attached to the internal wall of the sensory membrane. The structure of the organs suggest that an effective stimulus could be a compression of the membrane. A discussion of possible functions (pressure reception and hearing) is included.

Notizen: Scanning electron microscopy (SEM) of the surface tubercles of a specialized mechanoreceptor found within the head of Elaphe obsoleta lindheimeri indicates that the tubercle consists of a craterlike structure with a peg emerging from its center. After removal of the outer keratinized layers of the epidermis, the SEM discloses a replicate tubercle on the underlying alpha keratin layer. Over 6000 tubercles were found within a single snake. The mechanoreceptors were more densely concentrated on anterior scales, and their number appears to be species specific so that they are more concentrated in snakes with smaller heads than in those with larger ones.

Notizen: The interstitial nematode Theristus caudasaliens n. sp. normally locomotes by hopping on the left side of its tail tip, a mode of locomotion that is unique among nematodes. The animal uses its caudal glands and caudal musculature to perform the hops, attaching itself momentarily between hops with the glands and executing the hops by straightening and curling the posterior part of its body.The caudal gland apparatus can be seen by electron microscopy to consist of five gland cells of two different types. Three of these cells, termed viscid glands, are involved in adhesion of the animal to substrates and produce ovoid granules with a central dense band. The other two cells are characterized by smaller, lessdense granules and presumably function in releasing the animal from substrates. The ducts of both gland types extend to the tail tip where they terminate in a common crescent-shaped space. Their secretions are released to the outside through two pores on the left side of the tail tip. There is no spinneret valve in this nematode. The muscles of the tail and of the mid-body region are developed to the same extent.The caudal gland apparatus can be compared with the duo-gland adhesive organs of other interstitial animals, but its homology with either these organs or the caudal glands of other nematodes is uncertain. Theristus caudasaliens is described as a new species.

Notizen: The ventral surface of the most proximal tarsomere of each mesothoracic leg of the female black fly, Simulium venustum Say, bears approximately 60 bifurcate sensilla. Externally, a sensillum appears as a hair set into an asymmetric socket and with the distal tip flattened into two flared lobes. A single pore opens into a short groove at the base of the lobes. The hair shaft is divided into two lumina, one of which contains the dendrites. Each sensillum is innervated by four neurons, the dendrites of which extend unbranched to the pore. Sensillum liquor bathes the dendritic tips and extends through the pore into the adjacent groove and across part of the lobes. A sieve-like structure exists in the pore region of many if not all sensilla. At least two sheath cells are associated with each sensillum.It is suggested that, although the bifurcate sensilla have the internal structure associated with known contact chemosensilla, they have secondarily acquired an olfactory function which is facilitated by the flattened lobes which increase the adsorptive surface area.Along each side of the bifurcate sensilla is a row of sturdy spines, each innervated by a neuron with a tubular body, a characteristic of cuticular mechanoreceptors. These spines are likely tactile sensilla.

Notizen: Histology and cytology of dermal scales of the gymnophionans Ichthyophis kohtaoensis and Hypogeophis rostratus reveal their structure and the nature of their mineralization.Dermal scales are small flat disks set in pockets in the transverse ridges of the skin. Each pocket contains several scales of various sizes. A ring of “hypomineralization” of varying diameter may occur on scales of a particular dermal pocket but bears no relation to the diameter of these scales.Three different layers form the scales and are seen on sections perpendicular to the surface. The cells of the basal layer lie deepest. Each of the two or three more superficial fibrous layers is composed of bundles of fibres that are oriented in parallel. The orientation varies among layers. The striation of the fiber scales has a periodicity comparable to that of the surrounding dermal fibers. Squamulae form a discontinuous layer on the scale surface and are the only mineralized part of the scale. The minerals are deposited both on the collagen fibers passing from the fibrous layers into the squamulae, and in the interfibrillar spaces. Spherical concretions, either isolated or coalescent, reaching up to 1 μm, are found on the surface of the squamulae.The dermal scales of Gymnophiona present some analogies with those of evolved bony fishes. Their characteristics could make them an original model for the study of mineralization.

Notizen: Using light and electron microscopy, three hemocyte types are described in the hemolymph of the crayfish. The coagulocyte comprises 65% of the total hemocyte number and contains medium-sized cytoplasmic granules, abundant dilated rough endoplasmic reticulum, and a highly developed Golgi complex. It rapidly undergoes cytolysis in vitro and participates in coagulation by releasing the contents of its granules to the hemolymph. The granulocyte comprises 31% of the total hemocyte number and is capable of phagocytosis. It contains large, irregularly shaped cytoplasmic granules, a moderately developed Golgi complex, and moderate amounts of non-dilated rough endoplasmic reticulum. During coagulation in vitro, the cell attaches and spreads onto the substratum; this is followed by a slow intracellular granule breakdown and cytolysis. The amebocyte comprises 4% of the total hemocyte number and it is also capable of phagocytosis. It possesses small cytoplasmic granules, many vacuoles, a moderately developed Golgi complex, and large amounts of smooth endoplasmic reticulum. It is distinguished from the other two cell types by being stable and motile in vitro.

Notizen: Lateral cortex is the most laterally placed of the four cortical areas in snakes. Earlier studies suggest that it is composed of several subdivisions but provide no information on their organization. This paper first investigates the structure of lateral cortex in boa constrictors (Constrictor constrictor), garter snakes (Thamnophis sirtalis), and banded water snakes (Natrix sipedon) using Nissl and Golgi preparations; and secondly examines the relation of main olfactory bulb projections to the subdivisions of lateral cortex using Fink-Heimer and electron microscopic preparations.Lateral cortex is divided on cytoarchitectonic grounds into two major parts called rostral and caudal lateral cortex. Each part is further divided into dorsal and ventral subdivisions so that lateral cortex has a total of four subdivisions: dorsal rostral lateral cortex (drL), ventral rostral lateral cortex (vrL), dorsal caudal lateral cortex (dcL) and ventral caudal lateral cortex (vcL). Systematic analyses of Golgi preparations indicate that the rostral and caudal parts each contain distinct populations of neurons. Rostral lateral cortex contains bowl cells whose dendrites arborize widely in the outer cortical layer (layer 1). The axons of some bowl cells can be traced medially into dorsal cortex, dorsomedial cortex and medial cortex. Caudal lateral cortex contains pyramidal cells whose somata occur in layers 2 and 3 and whose dendrites extend radially up to the pial surface. In addition, three populations of neurons occur in both rostral and caudal lateral cortex. Stellate cells occur in all three layers and have dendrites which arborize in all directions. Double pyramidal cells occur primarily in layer 2 and have dendrites which form two conical fields whose long axes are oriented radially. Horizontal cells occur in layer 3 and have dendrites oriented concentric with the ependyma. Fink-Heimer preparations of snakes which underwent lesions of the main olfactory bulb show that the primary olfactory projections to cortex are bilateral and restricted precisely to rostral lateral cortex. Electron microscopic degeneration experiments indicate that the olfactory bulb fibers end as terminals which have clear, spherical vesicles and asymmetric active zones. The majority are presynaptic to dendritic spines in outer layer 1.These studies establish that lateral cortex in snakes is heterogeneous and contains two major parts, each containing two subdivisions. The rostral and caudal parts have characteristic neuronal populations. Primary olfactory input is restricted to rostral lateral cortex and seems to terminate heavily on the distal dendrites of bowl cells. Axons of some of these cells leave lateral cortex, so that the rostral lateral cortex forms a direct route by which olfactory information reaches other cortical areas. The functional role of caudal lateral cortex is not clear.

Notizen: The caudal neurosecretory system of the molly, Poecilia sphenops (Poeciliidae) was studied by light and electron microscopy. In this species the cell bodies form a focal nuclear group in the caudal spinal cord. The neurosecretory cells are in contact with glial elements, axon terminals, and the lumen of the central canal. The axons of the neurosecretory cells form a definitive tract, which leaves the spinal cord proper to penetrate a well defined neurohemal organ, the urophysis. The urophysis contains an abundance of neurosecretory granules within the neurosecretory axonal processes. This study is the first ultrastructural study of the caudal neurosecretory system in this family of fishes, which has been used as a neuroendocrine model. This species acclimates easily to the laboratory aquarium and may be most suitable for further studies on the effects of changes in external salinity on the caudal neurosecretory system.

Notizen: The relationships between dimensions of book lung subunits were measured and analyzed as a function of body size in diverse spiders over a body mass range of 3.4 to 3,190 mg. Book lungs are the characteristic respiratory gas exchange organs in these arachnids. Actual gas exchange occurs across numerous air-filled cuticular plates, which invaginate hemolymph sinuses within the abdomens of these animals. Characteristic linear dimensions of these air-filled compartments reflecting diffusion paths scaled to the 0.2 power of body mass and showed only a fourfold increase over the size range in the sample. This deviation from isometric scaling in the direction obtained and its numerical similarity to scaling of alveolar dimensions to body size in vertebrates was interpreted as an adaptation to reduce diffusion distances between these compartments and vascular fluids. Conversely, lengths and widths of these plates scaled to the one-third power of body mass, isometric scaling, and increased between six-and eightfold over the size range. This result is consistent with the hypothesis that respiratory gas distribution within spider lungs is achieved by convective mixing as has been recently hypothesized.

Notizen: This study carried out on the posterior caeca of Orchestia in intermolt by means of light and electron microscopy shows that the diverticula of the midgut consist of two segments which are different from an anatomical point of view. The distal segment is in close relationship to the dorsal blood vessel, whereas the proximal segment, twice as long as the distal one, only touches the haemocoel. The cells of the distal segment are characterized by a brush border, some apical extrusions, a great number of ribosomes, rough endoplasmic reticulum, often associated with the mitochondria, the matrix of which is clear, high activity of the Golgi complexes, and a great development of extracellular channels. All these features indicate an activity in synthesizing proteins and transport. In the proximal segment, the cells are characterized by a striated border, reduced intercellular space, and especially by a great development of the smooth endoplasmic reticulum sometimes associated with mitochondria having a dense matrix. These diverse features indicate absorption ion and water transport. From an ultrastructural point of view, the posterior caeca of Orchestia cannot be considered homologous to the Malpighian tubules. Whereas during molting the posterior caeca of Orchestia are sites of calcium storage, during intermolt they are probably involved in the processes of water and mineral regulation and excretion.

Notizen: The paired spermathecae of Rhodnius are simple tubular out-pocketings of the common oviduct. Each consists of a short muscular proximal duct and the distal glandular region with a blind tapering end. The spermathecal wall has a cuticular intima, slender columnar epithelial cells and ensheathing longitudinal striated muscle, connective tissue, tracheoles, and nerves. Glandular epithelial cells possess an elaborate apical secretion-filled tubular inpocketing with an extensively folded plasma membrane. Laterally, cells interact by desmosomes, septate desmosomes, and extensive interdigitations. The cytoplasm is rich in longitudinally oriented microtubules associating with membrane densities along the invagination, lateral, and basal plasmalemmae. Apical concentration of mitochondria suggests their role in secretion or ion transport. The possible role of the spermathecae in maintaining the stored luminal sperm and its role in transmitting the mating stimulus is considered in light of the epithelial ultrastructure. The ultrastructure of the spermathecae of Rhodnius differs significantly from that of other insects.

Notizen: Anatomical studies were conducted to characterize the source, type, and distribution of parathyroid gland innervation in European starlings. Denervation experiments demonstrated that the parathyroid glands and adjacent carotid bodies are innervated by nerve fibers originating in the nodose ganglion of the vagus nerve. In the parathyroid parenchyma, these fibers terminate adjacent to chief cells or near vascular smooth muscle. Vagal fibers also form synapses with catecholamine-containing glomus cells of the carotid body. Blood that first perfuses the carotid body subsequently perfuses the parathyroid parenchyma. These observations suggest that vagal innervation may influence parathyroid function in starlings either through direct chief cell innervation or through alteration of vascular perfusion. A neurohemal relationship also may exist between the carotid body and parathyroids.

Notizen: Voles and lemmings are the most successful group of graminivorous rodents, but the adaptations allowing them to enter this niche are not fully known. Dissections of the masticatory musculature of the 12 genera and subgenera of North American microtines show an increase in the potential anterior vector component and in the potential vertical vector component of these muscles relative to the molar tooth row. The result is a separation of the compressive and propulsive functions of the masticatory muscles during the power stroke of mastication. This has led to the formulation of a propalinal “swing” hypothesis which is supported by vector analyses of the musculature.

Notizen: The morphology of the bean-shaped accessory glands (BAGs) of males of Tenebrio molitor is described. All cells in the secretory epithelium are long and narrow (300-400 mμ × 5 mμ). The seven types of secretory cells are distinguished from one another by the morphology of their secretory granules. Granule substructure varies from simple spheres with homogeneous electrondense contents to complex forms with thickened exterior walls or with crystalline and membranous contents. Individual cell types were mapped by staining whole glands with Oil Red O, and the cell distributions were confirmed by wax histology and ultramicroscopy. The secretions of all seven cell types form a secretory plug composed of seven layers. During mating, the secretory plug from each BAG is forced into the ejaculatory duct by contractions of a sheath of circular muscle. The mirror image plugs from symmetrical BAGs fuse and are transformed into the wall of the spermatophore.

Notizen: Rickettsiae-like structures were found in the salivary gland cells of Drosophila auraria during different larval and prepupal developmental stages, from the early 3rd instar up to 14 hr after spiracle inversion. These microorganisms are surrounded by a membrane, are constantly intracellular, and occur singly or in groups. Their widespread occurrence in various tissues of other Drosophila species indicates that they can be considered as symbionts, but their actual functional significance (if any) is unknown.

Notizen: Histology of each of the five segments of the oviduct of the female turtle Chrysemys picta was described for successive intervals throughout their annual cycle. Uterine and glandular segments showed marked seasonal variations in the extent and content of the submucosal and epithelial glands. Submucosal glands were most prominent in preovulatory and postovulatory animals (May to June), regressing in late summer (oviposited animals) and recrudescing the following spring. These changes correlated with variations in the muscularis layer, the number of uterine epithelial blebs, oviductal vascularity, and the presence of eosinophils in cervical segment cross-sections. These cyclic seasonal changes are discussed in relationship to reported seasonal changes in gonadal steroids in this species. Hormonal control was corroborated by oviductal response to estradiol-17β injected (1 mg/kg daily for 2 weeks) into mature, reproductively inactive (winter) animals. This treatment induced increases in glandular activity, vascularity, and distribution of eosinophils comparable to those of reproductively active (summer) animals.

Notizen: Molluscan shells, including those of Gastropoda, are formed by accretionary growth at the mantle edge. The mantle is a thin membrane of skirt-like shape, which extends minutely beyond the aperture, and its edge adds a shell increment to the aperture margin so that each increment copies a configuration of the mantle edge at that time. Thus, regulation of shell morphogeny is almost equivalent to the factors which control the mantle form at the moment of shell growth. Form of the mantle skirt is considered to be kept in a state of balance between the force of its internal stress and forces acting on it such as fluid pressure or muscle contraction.The expansion behavior of the mantle skirt has been numerically analyzed by using an elastic model (DMS-tube), which represents the fundamental structure of the mantle tissue as a double membrane structure with internal springs (DMS). Four characteristic expansion patterns of the DMS-tube have been detected: (1) general outward expansion; (2) developing a ridge-like fold on an initial longitudinal protrusion of the tube edge; (3) drastic shift of the expanded state from a uniformly curved to an elliptical shape in outline, owing to the existence of a fixed boundary condition on the tube wall; and (4) constricted protrusion on the open region of the shell wall surrounding the DMS-tube. These results have the potential for answering the following questions relating to the morphogenesis of gastropod shells. How does the mantle skirt usually make contact with the inner surface of the shell wall so as to ensure continuous accretion of shell materials to the aperture margin? What is the cause of spiral ridges? Why do open coiling or minimally overlapping shells have generally circular apertures, while shells with apertures overlapped by whorls have non-uniformly curved apertural lips? What is the cause of long closed spines and why do they always appear on spiral ridges?

Notizen: The larval antenna of Bombyx mori has 13 sensilla and about 52 sensory neurons in its distal portion. The axons form two nerve cords which unite in the cranial hemocoel to supply the brain as the olfactory nerve. The antennal imaginal disc, which is a thick pseudostratified epithelium continuous with the antennal epidermis, thickens markedly during the 5th instar by rapid cell proliferation. At the prepupal stage cell proliferation ceases and the disc everts to form a large pupal antenna. Simultaneously, an extensive cell rearrangement occurs in the antennal epidermis and the disc tissue becomes much thinner because of the abrupt expansion of antennal surface area. The two larval nerve cords thin down markedly by degeneration of axons, but they do not disintegrate totally even after the onset of pupation. The epidermis of the larval antenna forms the distal portion of the pupal antenna, while the imaginal disc forms the more basal portion. Development to the adult antenna occurs almost immediately after the onset of pupation; many adult neurons appear in the simple epidermis facing toward the thick outer side of the newly formed pupal cuticle. By 12 hours after the onset of pupation, these neurons align themselves in many transverse rows which are the first sign of the adult antennal configuration. Addition of these neuronal axons to the once-thinned nerve cords causes resumed thickening of the cords during the first 24 hours and thereafter. Differentiation of adult sensilla begins in the next 24 hours and is almost completed at the third day of pupation, which requires a total of 10 days.

Notizen: Sensilla diversity and abundance were extremely high on the apex of the maxillary and labial palpi of two species of Gryllacrididae. The terminal segment of the maxillary palpi of these species had 9 and 15 sensilla types, respectively, and up to 2,834 sensilla. The labial palpi had 7 and 12 types, respectively, and up to 5,195 sensilla. Several types of multiporous smooth and ridged olfactory basiconic sensilla, and coeloconic, coelosphaeric, placoid, and multipapilliform sensilla occurred, as well as many trichoid sensilla and the more typical uniporous basiconic contact receptors. Two species of the closely related Stenopelmatidae were compared to the gryllacridids and found to have similar sensillar diversity and abundance, but three species of the more distantly related Tettigoniidae had only 4 or 5 sensilla types and a total number ranging from 320 to 960 on their maxillary palpi.

Notizen: The results of volumetric measurements led Hanström ('28) to suggest that specialized neuropil in the brain, the so-called central body (CB), may be of particular importance in the nervous control of web building behavior in spiders. We compared the volumes of the various brain regions in four spider species clearly differing in lifestyle and web building behavior: an orb weaver (Nephila clavipes), a wandering spider (Cupiennius salei), a jumping spider (Phidippus regius), and a bird spider (Ephebopus sp.). Our results obtained in adult animals as well as our observations on the postembryonic development of the brain do not support Hanström's hypothesis. The relative share of the CB in the brain is very similar in all four species (ca. 3.1 to 5.1%). The differentiation of the CB into a clearly demarcated two-lobed structure does not coincide with the onset of web building behavior in Nephila. The CB of both Nephila and Cupiennius is already clearly recognizable in spiderlings which have not even left the egg sac.

Notizen: The venom gland of Crotalus viridis oreganus is composed of two discrete secretory regions: a small anterior portion, the accessory gland, and a much larger main gland. These two glands are joined by a short primary duct consisting of simple columnar secretory cells and basal horizontal cells. The main gland has at least four morphologically distinct cell types: secretory cells, the dominant cell of the gland, mitochondria-rich cells, horizontal cells, and “dark” cells. Scanning electron microscopy shows that the mitochondria-rich cells are recessed into pits of varying depth; these cells do not secrete. Horizontal cells may serve as secretory stem cells, and “dark” cells may be myoepithelial cells. The accessory gland contains at least six distinct cell types: mucosecretory cells with large mucous granules, mitochondria-rich cells with apical vesicles, mitochondria-rich cells with electron-dense secretory granules, mitochondria-rich cells with numerous cilia, horizontal cells, and “dark” cells. Mitochondria-rich cells with apical vesicles or cilia cover much of the apical surface of mucosecretory cells and these three cell types are found in the anterior distal tubules of the accessory gland. The posterior regions of the accessory gland lack mucosecretory cells and do not appear to secrete. Ciliated cells have not been noted previously in snake venom glands.Release of secretory products (venom) into the lumen of the main gland is by exocytosis of granules and by release of intact membrane-bound vesicles. Following venom extraction, main gland secretory and mitochondria-rich cells increase in height, and protein synthesis (as suggested by rough endoplasmic reticulum proliferation) increases dramatically. No new cell types or alterations in morphology were noted among glands taken from either adult or juvenile snakes, even though the venom of each is quite distinct. In general, the glands of C. v. oreganus share structural similarities with those of crotalids and viperids previously described.

Notizen: 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.

Notizen: The micropylar apparatus (MA) in Rhagoletis cerasi (Diptera, Tephritidae) is located at the anterior pole of the egg and consists of two parts: an outer chorion and an inner vitelline membrane. Sperm entry takes place through the micropylar canal, 2.0-2.5 μm in diameter, which penetrates the micropylar endochorion and terminates in the thick vitelline membrane, thus forming the “pocket.” The pore of the micropylar canal, i.e., the micropyle, is covered by the exochorionic tuft.The formation of the MA is accomplished by 40 micropylar cells during oogenesis. These cells secrete the successive eggshell layers: the vitelline membrane, the wax layer, the innermost chorionic layer, the micropylar endochorion, and the exochorion. Two among 40 micropylar cells differentiate and form two tightly connected projections. The latter contain a bundle of parallel microtubules and participate in the formation of the micropylar canal and the pocket. At the tip of the projections there are two thin extensions full of microfilaments. In late developmental stages the two projections and the extensions degenerate and leave the canal and the pocket behind. We also discuss the structural features of the MA in relation to its physiology among Diptera.

Notizen: It is uncommon to find acid phosphatase activity in mature secretory granules. This paper demonstrates by light and electron microscope cytochemistry an acid phosphatase in mature secretory granules in the cells of one region of the salivary gland of Bradysia hygida (Diptera, Sciaridae). These secretory granules increase in number during larval development up to the beginning of the pre-pupal period when they undergo massive exocytosis. Biochemical assays show that upon exocytosis of the majority of the granules the total acid phosphatase activity in the granular gland region drops to 10% of the maximum reached before exocytosis. During and after exocytosis, two other acid phosphatases, eletrophoretically different and much weaker in activity, become increasingly detectable in all gland regions. At the same time, in whole mount preparations, numerous tiny acid phosphatase-positive granules (probably secondary lysosomes) become evident in all major cell types of the salivary gland. These results indicate that the S2 region of the salivary gland has mature secretory granules containing an acid phosphatase destined for exocytosis which is different in molecular properties from other acid phosphatases (likely lysosomal) made by the gland.

Notizen: The general histology and ultrastructure of the tongue and anterior process of the sublingual plica of four Taiwanese venomous snakes, the Chinese cobra (Naja naja atra), banded krait (Bungarus multicinctus), Taiwan habu (Trimeresurus mucrosquamatus), and bamboo snake (Trimeresurus stejnegeri stejnegeri) are described.The tongue fork exhibits a mid-dorsal invagination that broadens gradually toward its base. No mid-ventral invagination is observed. The epithelial cells on both dorsal and ventral aspects of the tongue fork have large and small microfacets, micropores and microvilli. The cell size, distribution pattern of the large microfacets, and the number of small microfacets present on both sides of the fork are essentially the same within a species, but vary among species. The function of these ultrastructures on the cell surface might be for the capture of chemical substances. The large microfacets are raised areas of the cell membrane, each with a pale granule contained within. The chemical nature of the pale granule is not yet known. The small pores surrounding the large microfacets are shallow hollows left after the release of the pale granules from the microfacets. The basic histological pattern of the tongue fork of these species is similar, being composed of a mucosal layer outside and dense musculature inside. No taste buds are discernible.The anterior processes are concave-like expansions of the anteriormost portions of the sublingual plicae. The oblique folds and micropapillae of this organ might be helpful for receiving the chemicals collected on the tongue, when the tongue makes contact with the elevated processes. The elevated processes may penetrate the ducts of Jacobson's organs to effect the final transfer.

Notizen: The scaleless notothenioid Gymnodraco acuticeps is a bottom dweller beneath the sea ice of McMurdo Sound, Antarctica. Gymnodraco experience unusual environmental conditions, including highly oxygenated subzero water. Skin morphology is evaluated with reference to its potential as a barrier to ice propagation and as a surface for cutaneous respiration. Light and electron microscopy and histochemistry reveal skin structure that is generally similar to that of other teleosts. In the epidermis, epithelial cells are arranged in nine to fifteen layers, and two types of mucous cells are also present. Large mucous cells are most common on external epidermal surfaces, whereas small cells are more frequent on internal epithelial surfaces. Epithelial cell junctions have extensive areas of desmosomes as well as interdigitations of the cell membranes, especially in the basal and midepidermis. The dermis consists of an exceptionally dense stratum compactum. The skin is thicker than that of Bovichtus, a scaleless temperate notothenioid from New Zealand. Mean skin thicknesses at sites on the trunk are 371-711 μm. With the exception of fins that contact the substrate, epidermal thickness between rays of most fins is 70-118 μm. The epithelial surfaces of the oral and branchial cavities are 27-50 μm thick. An unusual type of connective tissue is present beneath the epidermis of the pelvic fin. It contains abundant ground substance and is similar to mucous connective tissue of the mammalian umbilical cord. Perfusions of a microvascular filling agent reveal a moderately developed cutaneous vasculature. These vessels have the dimensions of capillaries (mean external diameter 11 μm). They are confined to the dermis and are more prominent on the head than on the trunk. The skin is secondary to the gills as a respiratory surface in Gymnodraco.

Notizen: 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.

Notizen: An immunohistochemical study of the localization of cytotactin and cytotactin-binding (CTB) proteoglycan throughout embryonic development of the anuran Xenopus laevis reveals that both appear in a restricted pattern related to specific morphogenetic events.CTB proteoglycan expression is first detected during gastrulation at the blastopore lip. Later, it is seen in the archenteron roof around groups of cells forming the notochord, somites, and neural plate. Cytotactin first appears after neurulation, and is restricted to the intersomitic regions. Both molecules appear along the migratory pathways of neural crest cells in the trunk and tail. Later, cytotactin is present at sites where neural crest cells differentiate, around the aorta and in the smooth muscle coat of the gut; CTB proteoglycan is absent from these sites. In the head, cytotactin is initially restricted to the regions between cranial somites, while CTB proteoglycan is distributed throughout the cranial mesenchyme. The expression of both molecules is later associated with key events in chondrogenesis during the development of the skull. After chondrogenesis, CTB proteoglycan is distributed throughout the cartilage matrix, while cytotactin is restricted to a thin perichondrial deposit. Both molecules are expressed in developing brain.These findings are compared to studies of the chick embryo and although distinct anatomical differences exist between frog and chick, the expression of these molecules is associated with similar developmental processes in both species. These include mesoderm segmentation, neural crest cell migration and differentiation, cartilage development, and central nervous system histogenesis.

Notizen: During metamorphosis of Xenopus laevis the extracellular matrix (ECM) proteins cytotactin and cytotactin-binding (CTB) proteoglycan, and the cell adhesion molecules N-CAM and Ng-CAM, appear in highly restricted patterns determined by immunofluorescence histology.During limb development, cytotactin appears from the earliest stages in a meshwork of ECM fibrils associated with migrating mesenchymal cells forming the limb bud. Cytotactin also appears in the ECM between the apical limb ectoderm and mesenchyme. Later, both cytotactin and CTB proteoglycan appear co-localized within the central (prechondrogenic) limb mesenchyme. During chondrogenesis in these areas, cytotactin becomes restricted to perichondrium, while CTB proteoglycan is expressed throughout the cartilage matrix. The premyogenic mesenchyme surrounding the chondrogenic areas expresses N-CAM. Later, N-CAM is concentrated at the myogenic foci where cytotactin appears at sites of nerve/muscle contact and in tendons.Expression of these molecules in the blastemas of regenerating limbs was also studied, and during development of the central nervous system, stomach, and small intestine.Analysis of the expression patterns of cytotactin and CTB proteoglycan throughout development and metamorphosis reveals several consistent themes. The expression of these molecules is highly dynamic, often transient, and associated with key morphogenetic events. Cytotactin appears at multiple sites where cells undergo a transition from an undifferentiated, migratory phenotype to a differentiated phenotype. One or both molecules appear at several sites of border formation between disparate cell collectives, and CTB proteoglycan expression is associated with chondrogenesis.

Notizen: In artificial fluid, the spermatozoa move as linear cells or round up and rotate, propelled by spontaneous bending of their tails. Both linear and rounded cells can move forward and backward, but usually they move forward. The tails of all cells display, simultaneously, small primary bends and fewer, much larger secondary bends. Rounded cells form single secondary bends that remain unchanged as the cells rotate. They also form “node-like” primary bends that travel posteriorly or anteriorly as the cells rotate forward or backward, respectively. Linear cells move their anterior regions into and out of focus in a cyclic fashion. They form rather prominent primary bends, as well as two to four secondary bends that travel posteriorly as the cells move forward. Secondary bends change in shape continuously and are not sinusoidal. The cells follow approximately linear trajectories, but the distances traveled per cycle, speeds, and secondary bending patterns are variable. When methyl cellulose is added to artificial fluid, linear movement is improved, and forward speeds are approximately tripled. The movement of spermatozoa in natural fluid of the female reproductive tract is remarkably less stereotyped than that of cells in artificial fluid. The cells, usually resembling straight lines or arcs, are very flexible and active. They lack obvious cyclic activity and double bending patterns. They are capable of moving both forward and backward and of adjusting their bending activity and speed within rather wide limits. Their average forward speed is about nine times faster than that of cells in artificial fluid.

Notizen: The neuromuscular organization of feline anterior sartorius was examined using three experimental approaches. First, the branching pattern of the nerve supplying anterior sartorius was inspected in muscles taken from a large number of feline cadavers. All muscles were found to be supplied by two major nerve branches, one directed proximally and the other directed distally, and most muscles (42/51) had a third distinct branch that entered the muscle centrally. Second, the motoneuronal populations supplying the three nerve branches were investigated by electrophysiological techniques. Motoneurons that supplied axons to the distally-directed branch did not appear to have collaterals in more proximally-located branches. In contrast, other motoneurons supplying the proximally-directed branch also appeared to supply axon collaterals to the centrally-directed branch. This result suggested that the motoneuronal population of the distally-directed branch was largely separate from that supplying the proximally- and centrally-directed branches. Third, the motor unit territories supplied by different nerve branches were mapped using glycogen-depletion methods. Muscle fibers supplied by the distallydirected nerve branch were mostly distributed to the medial portion of anterior sartorius, whereas the fibers supplied by the other two branches were generally found more anteriorly. Further, the muscle fibers supplied by an individual nerve branch were present in greater numbers at the end of the muscle closest to the entry point of that branch. Thus, the motor units supplied by discrete nerve branches were found to be distributed asymmetrically within anterior sartorius, but were arranged neither strictly in-parallel nor strictly in-series.

Notizen: The larvae of Halicryptus spinulosus bear six rings of sensory/ locomotory appendages. Twelve pedicellate flosculi, 6 dorsal and 6 ventral, are associated with the neck-lorica junction. Newly described are two rows of 4-5 flosculi present on the dorsal and ventral plates, and 2 tubuli located on each dorsolateral and ventrolateral plate near their junction with the midlateral plate. The ultrastructure of all organ systems is described. The multilayered lorica differs significantly from that of other priapulids. The anterior fourth of the lorica is not underlain by epidermal cells. At the junction of the introvert and neck are a series of adhesive tubuli that have groups of secretory cells basally. A gland is described at the junction of the fore- and midgut.

Notizen: 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.