bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface ultrastructure of the cornea and adjacent epidermis during metamorphosis of Rana pipiens A scanning electron microscopic study
Authors: Kaltenbach Jane C. , Harding Clifford V. , Susan Stanley
Published: February 2005

The external surface of the cornea and adjacent epidermis of larvae in representative developmental stages and of adult frogs, Rana pipiens, was studied by scanning electron microscopy. Surface cells are polygonal, usually hexagonal, in outline and covered with microprojections. During larval development prior to metamorphic stages, neither eyelids nor Harderian glands have developed; microprojections on the corneal surface are high and branched, and cell boundaries are elevated. On the anterior portion of the cornea and on the epidermis near the eye, the surface pattern is less dense, and ciliated cells are present. During metamorphic stages, corneal cell boundaries become less prominent and the pattern of microprojections more variable and markedly different from that of larvae of earlier stages. Corneal cells have a spongy appearance, are covered by a coating material, or are characterized as light or dark based on their brightness and surface texture. As eyelids develop in metamorphic stages XX–XXI, the numbers of ciliated cells increase dramatically, both on the corneal surface and on the edges of the developing lids. In later metamorphic stages XXII–XXV, lids and Harderian glands become well‐developed, and cilia are no longer observed. The adjacent epidermal surface becomes devoid of cilia but perforated by openings of cutaneous glands. Its spongy appearance is similar to that of both the cornea and neighboring epidermis of the mature frog. Changes in corneal surface features are probably metamorphic events associated with development of lids and Harderian glands and a shift from an aqueous to an air environment.
The kidney of Leptonychotes weddelli (Pinnipedia: Phocidae) with some observations on the kidneys of two other southern phocid seals
Authors: Vardy P. H. , Bryden M. M.
Published: February 2005

The structure of the kidney of Leptonychotes weddelli was examined using corrosion casts, India ink injection, and histological methods. Some observations were made on the kidney of the crabeater seal (Lobodon carcinophagus) and the elephant seal (Mirounga leonina). The kidneys in all three species are reniculate, as in many other marine mammalian species. Features that have not been described previously in a phocid seal are a peripyramidal muscle, and venous drainage characterized by a large extrinsic system and a small intrinsic system.

Examination of specialized fornices, relative medullary thickness, and the volumes of juxtamedullary relative to peripheral glomeruli (all of which relate to urine concentrating ability) revealed that each reniculus of Leptonychotes is similar to the unilobar kidney of a small mammal that produces only moderately concentrated urine. The high glomerular volume to cortical volume ratio may be related to high glomerular filtration rates after feeding observed in marine mammals.

It is concluded that reniculation is more likely to be related to the large size of most marine mammals than to some factor related directly to the marine environment.
Vasculogenesis of the bursa cloacalis (bursa of Fabricius) of the chick embryo
Authors: Schoenwolf Gary C. , Bell Laird A. , Watterson Ray L.
Published: February 2005

Vasculogenesis of the bursa cloacalis (bursa of Fabricius) was examined in 10‐ to 21‐day chick embryos and in chicks during the first 5 days post‐hatching. The entire circulatory system was injected with India ink, and the bursae were then removed and either cleared for examination in toto or sectioned serially. The bursa was supplied by three pairs of extrinsic blood vessels. At 10 and 11 days of incubation, most intrinsic vessels were arranged in a superficial, hexagonal network. In regions of developing plicae, the hexagonal plexus extended into the core of each plica, forming middle plical vessels. The latter were interconnected across interplical areas by cross‐connecting vessels. The middle plical vessels gave rise to small capillary offshoots, which soon increased in complexity, forming delicate loops. Branches extended from these loops through the subepithelial lamina propria to incipient epithelial buds by 12 days of incubation. All epithelial buds were supplied by at least one such branch, and similar branches extended to the basal aspect of the epithelium in areas where epithelial buds had not yet formed. This observation is consistent with the hypothesis that blood vessels induce formation of epithelial buds. At about 15 days of incubation, the cortex and medulla of each developing lymphatic follicle were defined clearly, and an intricate, web‐like, capillary network coursed throughout the follicular cortex. The medulla appeared to be devoid of capillaries. The diameters of all intrinsic and extrinsic bursal blood vessels gradually increased throughout development. During post‐hatching stages, the diameters of the extrinsic vessels continued to increase, whereas those of the intrinsic vessels were markedly decreased from late pre‐hatching stages.
The effects of androgens on the β‐glands of the tokay (Gekko gecko): Modification of an hypothesis
Authors: Maderson P. F. A. , Chiu K. W.
Published: February 2005

Study of the posterior abdominal epidermis in hypophysectomized/thyroidectomized male and female tokays following surgery, and subsequent androgen therapy, indicates that, contrary to a previous model, all aspects of β‐gland differentiation are under direct androgenic control. On the other hand, another epidermal specialization, the digital foot‐pad, shows a pattern of histogenesis directly comparable to that of β‐glands, but is unaffected by androgens. These data are discussed with respect to the evolution of glandular epidermal specializations in gekkonid lizards and the possible role of androgens in modifying the control of cell differentiation in lizard epidermis.
The cranial nerves of the teleost Trichiurus lepturus
Authors: Harrison George
Published: February 2005

The cranial nerves of the cutlassfish, Trichiurus lepturus, were described from their external brain origin to their most distal points. The nervus olfactorius, nervus opticus, nervus oculomotorius, nervus trochlearis, nervus abducens, nervus glossopharyngeus, and nervus vagus of Trichiurus are characteristic of teleosts. The cephalic autonomic nervous system also follows the general scheme for teleosts.

Atypical patterns are exhibited by portions of the ramus mandibularis facialis, ramus mandibularis trigemini, nervus stato‐acusticus, and nervus lineae later‐alis. A cutaneous ramus mandibularis externus facialis arises from the ramus mandibularis; this cutaneous nerve has been recorded specifically in only certain siluroid catfish. A connection from the ramus mandibularis trigemini to the cutaneous ramus mandibularis externus facialis is present; an equivalent of this connection has been reported only in the silversides, Menidia, and the siluroid catfish Parasilurus. This nerve pattern probably represents an archaic arrangement. The nervus stato‐acusticus of Trichiurus is typical for teleosts, except for a branch extending from the posterior part of the nerve; this branch sends connections to the nervus lineae lateralis and then exits the cranium via the vagus foramen. Connections between the nervus lineae lateralis and the nervus stato‐acusticus have previously been reported in only the hatchetfish, Argyropelecus, and the bristle‐mouth, Cyclothone. This condition may represent a specialized adaptation of certain mesopelagic teleosts having extreme vertical‐migration capabilities.
Evidence for the holocrine nature of lipoid secretion by avian epidermal cells: A histochemical and fine structural study of rictus and the uropygial gland
Authors: Menon G. K. , Aggarwal S. K. , Lucas A. M.
Published: February 2005

Cells of the avian epidermis (rictus of the chicken), when examined under the light microscope following suitable fat staining, show similarities to epithelial cells of the uropygial gland of chicken and pigeon, an organ which is recognized both morphologically and functionally as a holocrine gland. Evidence thus far from electron microscopic studies strongly suggests that the skin of the bird is also a holocrine gland, although details of cytogenesis and secretion differ somewhat in the two organs.
Morphogenesis of the hereditary microphthalmia in a new strain of rat
Authors: Kobayashi Kenji , Otani Katsumi
Published: February 2005

Morphogenesis of the eye was studied in a new strain of micro‐phthalmic rat. Abnormalities were noted immediately after the formation of the optic cup. The inner layer in the central part of the optic cup was relatively thick and contained many mitotic figures, whereas that of the marginal part was thin and contained only a few. The transitional point in the inner layer between the central and the marginal parts was well marked. This is evidently due to the extreme growth inhibition of the inner layer at the marginal part.

At the early developmental stage, an area of the inner layer corresponding to the transitional point protruded toward the lens because the central part of the inner layer continued to differentiate.

The differentiation and the protrusion of the inner layer proceeded variably at the later stages depending on the degree of the growth inhibition. The eyes were classified into three groups: Group A–the retina was recognized as a cyst consisting of the pigment layer and the pigment‐layerlike structure which originated from the inner layer; group B‐the neural retina and its layered structure were inverted; group C‐abnormalities, such as the destruction of the lens, were observed.

Although previous authors who studied eye mutants suggested the vascular abnormality as the primary cause of the production of abnormal eyes, we feel that this is not the case in our animals.
Characteristics of gonads and oviducts in hatchlings and young of Chelydra serpentina resulting from three incubation temperatures
Authors: Yntema C. L.
Published: February 2005

Eggs of Chelydra serpentina were incubated at 30°C and 26°C. In addition, incubation was done at 20°C during the temperature‐sensitive period for sex determination. Incubation at 20°C and 30°C resulted in females; incubation at 26°C resulted in males in 99% of the cases. The average gonadal length was less in the males. The average length of the 20°C ovaries did not vary significantly from that of the 30°C ovaries.

The condition of the oviducts was correlated with histology of the gonads in hatchlings and in 3‐month‐old animals. When at least one of the oviducts was obvious and intact, ovaries were present. If the oviducts were absent or interrupted, testes were present. Histological characteristics of the gonads resulting from the three incubation temperatures are described. In the 26°C testes, cellular infiltrations occurred frequently. The ovaries of 20°C hatchlings tended to have a less developed germinal epithelium than that of the 30°C animals. Also, epithelial cysts occurred frequently in the 20°C ovaries. The incidence of follicles at 3 months was not differential.
Johnston's organ in Neodiprion sertifer (Insecta: Hymenoptera)
Authors: Hallberg Eric
Published: February 2005

The fine structure of Johnston's organ in the pine sawfly, Neodiprion sertifer, was studied by electron microscopy to determine if there exists a dimorphism in this organ corresponding to the sexual dimorphism in antennal shape and surface area.

The organ is made up of scolopidia that are ultrastructurally similar to those of other insects. The scolopidia, identical in both sexes, comprise three sensory cells bearing two types of sensory processes: Two are shorter and smaller in diameter than the third, which extends into the cuticle of the membrane connecting pedicel and flagellum and terminates at an epicuticular invagination. The dendrites and sensory processes are surrounded by two types of enveloping (glial) cells‐a scolopale cell and an attachment cell. Other enveloping cells occur at different levels of the scolopidium.

Sexual dimorphism is evident only in the numbers of scolopidial groups: Males have more groups with fewer scolopidia, but both sexes possess about the same total number of scolopidia.
A stereological analysis of developing egg chambers in Ephestia kuhniella
Authors: Torres Joseph
Published: February 2005

A polytrophic ovariole of the flour moth, Ephestia kuhniella, is composed of a linear series of increasingly mature egg chambers, each consisting of an oocyte, an interconnected cluster of seven nurse cells, and a covering layer of follicle cells. This study describes changes in the volume of each component as a function of the position of the egg chamber in the ovariole. Analysis of the growth curve of the Ephestia oocyte yields two possible correlations between accelerated oocyte growth and ultrastructural events enhancing the supply of yolk materials to the oocyte: the first is the initiation of yolk synthesis by the follicle cell layer and its transfer to the oocyte, and the second is the formation of channels between the follicle cells allowing hemolymph to gain access to the oocyte. An Ephestia oocyte increases in volume from approximately 2.5 × 103 μm3 to approximately 2.0 × 107 μm3 over an average series of 58 egg chambers.
Allometric analysis of the morphometric pulmonary diffusing capacity in dogs
Authors: Gehr Peter , Siegwart Benno , Weibel Ewald R.
Published: February 2005

The lung volume, the morphometrically determined alveolar and capillary surface area, and the capillary volume of 27 dogs (weight 2.65–57 kg) all were linearly correlated with body weight. The thickness of the air‐blood barrier increased only slightly with increasing body size. The structural diffusing capacity, containing these parameters, was used to estimate the gas exchange capabilities of the lung and was also found to scale in direct proportion to body size. This coincides with reports on physiologically estimated diffusing capacity but is obviously different from the interspecies slope for metabolism which scales to the 3/4 power of body weight.
Experimental regeneration of the caudal skeleton of the glass knifefish, Eigenmannia virescens (Rhamphichthydae, Gymnotoidei)
Authors: Kirschbaum Frank , Meunier Francois Jean
Published: February 2005

This paper describes the regeneration of the caudal axial skeleton after amputation of the tail, including about 20 vertebrae, in the gymnotoid fish Eigenmannia virescens. Seven days after amputation, a regeneration blastema developed and soft tissues degenerated. A cylinder of cartilage developed at the end of the notochord. When this cartilage was about 10 mm long (21 days), perichondral ossification began. The cartilage continued to elongate and ossification increased while osteoclasts began to destroy the cartilage ventrally. Finally, a bony rod formed and at its tip the cartilage persisted as a rod, 2 to 3 mm long. The anal fin also regenerated: Endoskeletal cartilage developed first, following by differentiation of the lepidotrichia, and finally ossification of the endoskeleton.
Early ultrastructural changes of developing oocytes in the dog
Authors: Tesoriero John V.
Published: February 2005

Many aspects of the developmental stages of the oocyte of the dog resemble those of other mammalian species. The oocyte of the dog, however, contains large amounts of lipid yolk material. A study of the ultrastructural morphology of early growth and maturation of dog oocytes was undertaken to clarify the nature and appearance of this yolk material. The lipid yolk first appears in early primary oocytes as aggregated dense bodies that gradually fill the ooplasm as the oocyte matures. The site of the yolk's initial appearance is consistently related to a single centriole and often to the lamellae of smooth endoplasmic reticulum that surrounds groups of forming lipid yolk bodies. Dense cortical granule‐like vesicles are found to lie deep within the maturing oocyte and often are enclosed within the lamellar yolk space. Granules within this space undergo changes in size, matrix configuration, and vacuolization. These changes suggest a mechanism whereby material is added to the lipid yolk bodies. Light microscope histochemistry for lipid and polysaccharide material is described.
Morphological evidence for probable secreting site for the pheromone “seducin” in males of Nauphoeta cinerea. I. Light microscope studies
Authors: Menon Maya
Published: February 2005

Males of the cockroach, Nauphoeta cinerea (Olivier), possess a thickened secretory epithelium limited to the inner surfaces of sternites three to seven and tergites two to eight. The epithelium consists of three cell types: 1. large columnar secretory cells, 2. squamous nonsecretory cells, and 3. duct cells. Type 1 cells constitute the innermost layer and contain large nuclei and vacuoles, which are especially prominent in the epidermis of older males. This cell type may be involved in “seducin” secretion. Type 2 cells lie in the narrow basophilic zone which separates the secretory cells from the cuticle. Here, cellular boundaries are poorly defined. Type 3 cells with condensed nuclei are associated with cuticular ductules leading from the epidermis to the exocuticle. The epidermal height in the secretory zone of the sclerites approaches 40–200 μm depending on the age of the male. The changes in appearance of the secretory cells (increase in height and vacuolation) indicate heightened secretory activity. This is supported by the results obtained when extracts of these regions from different aged males are bioassayed for pheromone (Dimeo et al., '78). A striking difference in the morphology of the cuticle and epidermis of the secretory halves of sternite and tergal integument is noticeable.
A quantitative analysis of mitotic gradients during early development in Calliphora erythrocephala Meig. (Diptera)
Authors: Lundquist Anders
Published: February 2005

Mitotic waves during superficial cleavage and early gastrulation were analyzed quantitatively in Calliphora. Three consecutive patterns are present: (1) a monotonic anterioposterior mitotic gradient during early superficial cleavage; (2) a double mitotic gradient from the anterior and posterior poles during superficial cleavage, especially toward the end of the period; and (3) more complicated patterns with intermediate mitotic centers during the last superficial cleavage division and during early gastrulation. Mitotic gradients are absent in many eggs during early superficial cleavage, but they then become ubiquitous. The gradients are longitudinal; no transverse component was detected before gastrulation. Anterior and posterior gradient patterns are not mirror images of each other; mitotic activity always starts earlier anteriorly. The gradients are accompanied by a pronounced increase in interphase length. The mitotic gradients are compared with the morphogenetic gradients predicted in a current model for pattern specification in insect eggs.
Microanatomy of the renal cortex in the domestic fowl
Authors: Wideman Robert F. , Braun Eldon J. , Anderson Gary L.
Published: February 2005

Two aspects of the avian renal cortical microanatomy previously were unclear. The precise in situ folding patterns and orientations of the nephrons with respect to the other cortical elements had not been demonstrated. It also was not known whether certain nephron segments are supplied exclusively by either the arterial or the portal blood flow. In the present study, a new casting compound was developed to allow selective examination of the cortical components by light microscopy. Cortical nephrons at the surface of the kidney were serially sectioned and reconstructed in order to determine: (a) their relationships to the vasculature and collecting ducts; (b) the location and characteristics of the tubule segments; and (c) the primary and secondary folding patterns of the tubules. The anatomical findings were documented individually and then summarized in a comprehensive diagram of the superficial cortical microanatomy. In addition, an in vivo method was used to determine the extent of portal blood distribution to the nephron segments. It was demonstrated that renal portal blood suffuses all of the segments except for the loops of Henle.
Sensilla of the antennae and the labial and maxillary palps of Blattella germanica (L.) (Dictyoptera: Blattellidae): Their classification and distribution
Authors: Ramaswamy S. B. , Gupta A. P.
Published: February 2005

The various sensilla on the antennae and on the labial and maxillary palps of Blattella germanica (L.) were studied. Thick‐walled chemoreceptors with fluted shafts and articulated bases are located on the antennae and on the labial and maxillary palps. Thin‐walled chemoreceptors, without fluted shafts or articulated bases, are restricted to the flagellar segments of the antennae and to the distal segments of the palps. Antennae of adult males have more thin‐walled chemoreceptors than do those of females. Hair‐plate sensilla are found at the scape‐head and scape‐pedicel joints, and at the joints of segments on the palps. Campaniform sensilla are concentrated as a ring around the distal margin of the pedicel, and are also scattered singly on the scape, pedicel, and flagellar segments of the antennae, and on the first segment of the maxillary palps. Occasionally, a few sensilla coeloconica and cold receptor sensilla are found on the antennal flagellum.
Observations on preadipocytes and their distribution patterns in rat adipose tissue
Authors: Askew E. W. , Schuschereba S. T. , Brown J. P. , Hecker A. L.
Published: February 2005

Microscopic examination of adipocytes isolated from adult rat epididymal adipose tissue revealed numerous small cells (< 10 μm) morphologically similar to larger adipocytes. These small adipocytes appear identical to a new classification of adipose cells termed preadipocytes. Electron micrographs of these preadipocytes revealed examples of cells < 10 μm in diameter in various stages of maturation and lipid accumulation. The percent distribution pattern of these small adipocytes was not significantly altered by exercise although exercise shifted the distribution patterns of the larger cells (> 30 μm) toward a smaller mean cell size. The quantitative significance of preadipocytes is not established but these preliminary observations indicate that adipocytes < 10 μm in diameter may account for a numerically greater proportion of the total adipocytes observed in collagenase isolated preparations than heretofore recognized, although their contribution to total adipose mass is probably negligible.
Limb regeneration following the discontinuation of growth hormone therapy in the hypophysectomized newt, Notophthalmus viridescens
Authors: Landesman Richard , Hessler Arthur C.
Published: February 2005

Untreated adult newts do not undergo normal limb regeneration following hypohysectomy. A fibrocellular dermal barrier (cicatrix) atypically forms between the apical epithelium and the underlying mesenchymal tissues. Historically, continuous administration of growth hormone or of prolactin in combination with thyroxine restored regenerative capacity to these newts. In a previous investigation, we demonstrated that the initial effect of these two hormone treatments, when administered on alternate days to hypophysectomized newts beginning eight days post‐amputation, was to facilitate the erosion of the fibrocellular barrier and establish the epithelial mesenchymal interface that is observed in a regenerating limb.

The present investigation was designed to evaluate the necessity of continuous hormone therapy to maintain limb regeneration in hypophysectomized newts. One, two, or three injections of growth hormone or of prolactin in combination with thyroxine was administered on successive alternate days to hypophysectomized newts either immediately following limb amputation (ID) or beginning eight days post‐amputation (DD). The ID and DD newts receiving one, two, or three injections of growth hormone showed evidence of regeneration to the digitiform stage by day 30 post‐amputation, while those receiving prolactin and thyroxine underwent wound healing. While both hormone treatments initially promoted a dermis‐free apical epithelium, only hypophysectomized newts that had received growth hormone were able to continue regenerating.

We have, therefore, concluded that discontinuous growth hormone therapy is sufficient to initiate and maintain the conducive environment for limb regeneration to advanced stages in the hypophysectomized newt. While initiating this process, prolactin and thyroxine therapy on a discontinuous regime does not maintain regeneration. The direct and indirect role of growth hormone in supporting limb regeneration in normal and hypophysectomized newts is discussed.
External features of embryonic development of a jumping bristletail, Pedetontus unimaculatus Machida (Insecta, Thysanura, Machilidae)
Authors: Machida Ryuichiro
Published: February 2005

The external features of the embryo and the first instar larva of Pedetontus unimaculatus are described. Blastokinesis of P. unimaculatus is very similar to that of Petrobius brevistylis (Larink, '69), but differs from that of Machilis alternata (Heymons and Heymons, '05). The superficial structures of three pairs of protocerebral lobes are present. The terga of the mandibular, maxillary, and labial segments take part in the formation of the head capsule. In the maxilla and labium, the palpi are homologous with the telopodites of the legs; the other parts proximal to the palpi are homologous with the coxopodites. No sternal element contributes to the postmentum. Both glossa and paraglossa consist of two lobes. The pleuropodium, stylus and ventral sac are derived from distal parts of appendage anlagen. The pleuropodium of the first abdominal segment is homologous with the styli of the successive abdominal segments; the ventral sacs of succeeding segments are serially homologous. The basal parts of appendage anlagen cover each sternum in the first to ninth abdominal segments to form coxites, which are therefore appendicular in origin. The basal part of the cercus also covers the ventral and lateral surfaces of the eleventh abdominal segment.
The embryonic development of the primitive moth, Neomicropteryx nipponensis Issiki (lepidoptera, micropterygidae): Morphogenesis of the embryo by external observation
Authors: Kobayashi Yukimasa , Ando Hiroshi
Published: February 2005

The micropterygid moth Neomicropteryx nipponensis belongs to the most primitive suborder Zeugloptera of the Lepidoptera. During embryogenesis the small circular germ disk formed on the ventral egg surface invaginates deeply into the yolk. It finally separates from the egg periphery or rudimentary serosa, and becomes a sac‐shaped germ rudiment. Its anterior part later develops into the germ band, while its posterior part is the future amnion. Just before revolution of the embryo, the embryo assumes a completely superficial position beneath the yolk. Neither amnion nor serosa rupture during revolution; by completion of dorsal closure they have been incorporated into the yolk to form the secondary dorsal organ.

The formation of the germ rudiment and embryonic membranes in N. nipponensis resembles those of swift moths, Endoclyta (suborder Monotrysia) and of the caddisflies, Stenopsyche (Trichoptera), but differs from those of ditrysian Lepidoptera. The secondary dorsal organ has never been found in any other lepidopteran embryos; however, it is formed in N. nipponensis and in the Trichoptera. The results of the present study strongly support the general phylogenetic views that the Zeugloptera have a close affinity to the Trichoptera.
Olfactory bulb efferents in the channel catfish, Ictalurus punctatus
Authors: Bass Andrew H.
Published: February 2005

Autoradiographic, HRP, and Fink‐Heimer techniques define olfactory bulb efferents in the channel catfish. The olfactory bulb projects bilaterally to eight targets in the area ventralis telencephali including the preoptic area, five targets in area dorsalis telencephali, and the posterior tuber of the diencephalon. There is additional input to the peripheral margin of the internal cell layer of the contralateral olfactory bulb. Fibers cross in rostral (nervus terminalis and commissure of Goldstein) and caudal components of the anterior commissure and the habenular commissure. HRP techniques reveal the origin of bulb efferents from the internal and mitral cell layers of the olfactory bulb. The olfactory tract is divided into five major components, each with a unique subset of ipsilateral and commissural pathways.
The cytoarchitecture of the torus semicircularis in the red‐eared turtle
Authors: Browner Robert H. , Kennedy Michael C. , Facelle Thomas
Published: February 2005

The cytoarchitecture and neuronal morphology of the torus semicircularis in the red‐eared turtle, Chrysemys scripta elegans, were examined in Nissl‐stained and Golgi‐impregnated material. The torus semicircularis begins in the caudodorsal mesencephalon and extends rostrally and laterally to end ventrally to the tectal ventricle. The torus semicircularis consists of a central nucleus and a laminar nucleus, which is interposed between the central nucleus and the ventricle.

The central nucleus can be divided into two regions, a small, large‐celled area, located dorsally, and a larger area of small spherical (6–17 μm), large spherical (18–25 μm), triangular (15–27 μm) and fusiform (10–26 μm) neurons. The small spherical cells have two dendritic patterns: “radiate” and “single.” The radiate pattern has a dorsoventral orientation, several secondary branches and few dendritic spines. These cells are usually located in the center of the central nucleus. The single pattern is oriented mediolaterally. This cell type is most often observed at the periphery of the central nucleus. These neurons have few secondary branches and dendritic spines. The large spherical neurons display two dendritic orientations: dorsoventral and mediolateral. All dendritic trees have numerous secondary branches and few dendritic spines. The triangular neurons exhibit primary dendrites projecting from the corners of the somata and have few secondary branches and dendritic spines.

The fusiform neurons have a majority of their dendrites oriented mediolaterally, few secondary branches and a small number of dendritic spines.

The laminar nucleus consists of several layers and three cell types: ovoid (9–15 μm), triangular (20–40 μm), and fusiform (20–40 μm). All neurons have few secondary dendritic branches and few dendritic spines. The dendrites of many neurons course perpendicularly to the long axis of the brainstem and encapsulate the central nucleus. Some ovoid and fusiform neurons display dendrites that enter the central nucleus.
The torus semicircularis in a gekkonid lizard
Authors: Kennedy Michael C. , Browner Robert H.
Published: February 2005

The cytoarchitecture and neuromorphology of the torus semicircularis in the tokay gecko, Gekko gecko, were examined in Nissl‐stained, fiber‐stained, and Golgi‐impregnated tissues.

From a superficial position, the torus semicircularis extends rostrally under the caudal half of the optic tectum. Caudally, the two tori abut upon one another; rostrally, they diverge. The torus semicircularis consists of central, laminar, and superficial nuclei.

The central nucleus consists of fusiform, spherical and triangular neurons. Their dendrites are highly branched, with numerous dendritic spines, and are oriented mediolaterally, dorsoventrally, and rostrocaudally. Fusiform and spherical neurons display two dendritic patterns: “single axis,” ramifying in one axis, and “dual axis,” exhibiting higher‐order branches perpendicular to the primary dendrites. Triangular neurons exhibit a “radiate” dendritic pattern.

In the rostral half of the torus semicircularis, the laminar nucleus caps the central nucleus. The laminar nucleus encircles the central nucleus in the caudal torus semicircularis. The neurons of the laminar nucleus have dendritic arrays oriented parallel to the border of the central nucleus. These dendrites exhibit a paucity of dendritic spines and higher‐order branches. Fusiform and spherical neurons exhibit “single axis” and “dual axis” dendritic patterns. Triangular neurons display “radiate” patterns.

The caudal superficial nucleus lies dorsal and dorsolateral to the central nucleus. The superficial nucleus is sparsely populated by small fusiform and spherical neurons with moderately branched dendrites and moderate numbers of dendritic spines. These neurons display “single axis” (fusiform neurons) as well as “dual axis” and “radiate” (spherical neurons) dendritic patterns. They are oriented either parallel to or perpendicular to the boundary of the laminar nucleus.
A Study of the influence of the ambient microflora on the structure of lung alveolar macrophages and an ultrastructural comparison of lung and peritoneal macrophages in germ‐free and conventionally reared mice
Authors: Woodward B.
Published: February 2005

In order to investigate quantitatively and objectively the influence of the normal microbial flora on the ultrastructure of the alveolar macrophage, three groups of mice were studied stereologically: germ‐free (GF), conventionally reared under non sterile isolation conditions (IC), and conventionally reared in an open environment (OC). The alveolar macrophages of GF mice possess a smaller mitochondrial compartment, possibly with fewer organelles, than the macrophages of conventional mice. Other influences of the normal microflora on alveolar macrophage substructure are obscured by the effects of nonmicrobial stimuli such as droplets of lung surfactant.

No previous comparison exists of alveolar and peritoneal macrophage ultrastructure. Lung macrophages are larger than the phagocytes of the peritoneum, but the difference in size is much less than is commonly believed. Alveolar macrophages are rounder than peritoneal macrophages, and exhibit much less rough endoplasmic reticulum (RER) as well as differences in mitochondrial morphometry. No difference in mitochondrial volume fraction exists between the two types of macrophage even though alveolar macrophages represent the extreme of aerobic adaptation in the mononuclear phagocyte system. Phagosomes occupy a significant fraction of cellular volume only in the alveolar macrophages. Moreover alveolar phagocytes contain fewer but larger lysosome‐like granules than are found in peritoneal macrophages. The results represent the first objective, quantitative structural evidence confirming the common belief that alveolar macrophages experience greater physiological stimulation than peritoneal macrophages. The normal microflora accounts for only a small proportion of the differing degree of stimulation exerted on the two types of macrophage.
An electron microscopic study on the innervation of the gill filaments of a lamprey, Lampetra japonica
Authors: Nakao Taisuke
Published: February 2005

This paper reports observations on the innervation of gill filaments of the lamprey, Lampetra japonica. Nerve fibers run on each side of the afferent filament artery (AFA nerve) and in the connective tissue compartment along the efferent filament artery (EFA nerve). The AFA nerve supplies vasomotor fibers to the afferent filament artery and arteriovenous anastomoses and special visceral motor fibers to branchial muscle fibers (musculus compressor branchialis circularis). Nerve endings of the vasomotor fibers contain large, cored vesicles (60–180 nm in diameter) with a variable number of small, clear vesicles (30–70 μm in diameter), whereas those of the visceral motor fibers have many small, clear vesicles with few large, cored vesicles. The EFA nerve supplies vasomotor fibers to the efferent filament artery. Their endings, containing mixtures of predominantly large, cored vesicles and small, clear vesicles make close synaptic contacts with reticular cells. The latter in turn are connected with each other or with smooth muscle cells in the wall of the efferent filament artery by nexuses. No nerves are found in the axial plate between the afferent and efferent filament arteries nor in the secondary lamellae of individual gill filaments. No afferent nerve supply to the gill filament has been found.
Retinal afferents and efferents of an infrared sensitive snake, Crotalus viridis
Authors: Schroeder Dolores M.
Published: February 2005

The retinal afferents and efferents were examined in Crotalus viridis. Retinofugal fibers were traced by injecting horseradish peroxidase (HRP) or tritiated leucine into the eye, or by removing the eye and staining degenerating axons with silver methods. Terminations were seen contralaterally in the suprachiasmatic nucleus, the dorsal and ventral lateral geniculate nuclei (extensive), the pretectal nuclei, including the nucleus posterodorsalis (a very heavy input), the nucleus lentiformis mesencephali, nucleus geniculatus pretectalis, and nucleus pretectalis, the superficial layers of the optic tectum, including the stratum zonale, the stratum opticum, the stratum griseum et fibrosum centrale and the upper portion of stratum griseum centrale, and the basal optic nucleus. Ipsilateral input reaches the intermediate portion of the dorsal lateral geniculate nucleus, a small portion of the pretectal nucleus and nucleus posterodorsalis, and the basal optic nucleus (very minimally). Retinopedal fibers were traced with the HRP method. The cell bodies lie in the ventral thalamus within the nucleus of the ventral supraoptic decussation. These neurons project primarily to the contralateral retina, but some more rostrally located neurons project to the ipsilateral retina.
The fully formed chondrocranium of the agamid lizard, Agama pallida
Authors: Zada Suher
Published: February 2005

Major features of interest in the mature chondrocranium of Agama pallida are striking curvature of the nasal region, lack of the paranasal cartilage and concha nasalis, and presence of a cartilaginous roof over Jacobson's organ. In addition, the course of the ethmoid nerve deviates from the normal lacertilian pattern; there is no foramen epiphaniale, and the temporal region is reduced. The prefacial commissure and facial foramen lie in front of the cochlear portion of the auditory capsule, whereas the prominentia semicircularis anterior is separated from the rest of the otic capsule. Several chondrocranial characters are suggested to be unique to the agamids.
Mandibular movement and muscle activity during mastication in the guinea pig (Cavia porcellus)
Authors: Byrd Kenneth E.
Published: February 2005

Optoelectronic analysis of mandibular movement and electromyography (EMG) of masticatory muscles in Cavia porcellus indicate bilateral, unilateral, and gnawing cycles. During bilateral and unilateral cycles, the mandibular tip moves forward, lateral, and down during the lingual phase of the power stroke to bring the teeth into occlusion. EMG activity is generally asymmetric, with the exception of activity of the temporalis muscle during bilateral cycles. During gnawing cycles, the mandible moves in an anteroposterior direction that is opposite that during bilateral and unilateral chew cycles. Bilateral and unilateral cycles of pellets were significantly longer than carrot. With the exception of the width of bilateral cycles, the magnitude of cycle width, length, and height during the mastication of carrots was greater than that during the mastication of pellets. Significant differences exist between EMG durations during mastication of pellets and carrots. The lateral pterygoid displays continuous activity during gnawing cycles. Significant differences also exist in the durations of EMG activity between the working and balancing side during all three cycle types. High level activity of balancing side temporalis and anterior belly of digastric (ABD) during bilateral cycles occurs during rotation and depression of the mandible during the power stroke. The temporalis apparently provides a „braking”︁ or compensatory role during closing and power strokes. Differences between Cavia masticatory patterns and those shown by Rattus and Mesocricetus are apparently due to differences in dental morphology, occlusal relationships, and, possibly, the poorly developed temporalis in Cavia. The large number and wide diversity of rodent groups afford students of mammalian mastication an opportunity to investigate and compare different masticatory specializations.
Morphological and ultrastructural aspects of Branchiobdella pentodonta Whit. (Annelida, oligochaeta) suckers
Authors: Farnesi Rosalba M. , Marinelli Marinella , Tei Simonetta , Vagnetti Daniela
Published: February 2005

The muscular system in the posterior sucker of Branchiobdella pentodonta Whit. has circular, longitudinal and radial fibers. In the anterior sucker, which has circular and longitudinal fibers, the muscle system is scarce. Concentric fibers are found around the mouth. In both suckers the glandular elements form voluminous complexes secreting mucus for attachment to the substrate. Suckers show neuromuscular junctions and three distinct types of neuroglandular junctions: one with typical neurosecretory granules, one with larger neurosecretory granules produced by cells located at the origin of the segmental nerves, and one with presynaptic vesicles. The second type is peculiar to the posterior sucker. A comparison is made between suckers of Branchiobdella and those of leeches.
Ultrastructure of the heart of the marine mussel, Geukensia demissa
Authors: Watts John A. , Koch Robert A. , Greenberg Michael J. , Pierce Sidney K.
Published: February 2005

The structure of the heart of Geukensia demissa, a common object of physiological and biochemical investigation, is described by scanning, transmission and freeze‐fracture electron microscopy. A single‐cell epithelial layer covers the ventricle, but an endothelium is lacking. Myofibers are small (6–7 μm diam.), mononucleate, and tapered. Glycogen is concentrated peripherally. Mitochondria are particularly concentrated under the sarcolemma, near the ends of the nucleus, and in rows between bundles of myofilaments. The myofilaments (6–8nm thin, 30–35 nm thick filament diam.) are loosely arranged into sarcomeres (2–4 μm) by Z bodies. Many of these Z bodies interconnect, and some anchor to the sarcolemma forming attachment plaques. Cells are joined by intercalated discs consisting of fascia adherentes, spot desmosomes, and gap junctions. The gap junctions include intramembrane particles. T tubules are absent. The sarcolemma is coupled to the junctional sarcoplasmic reticulum (JSR) over 357ndash;40% of the cell surface. Tubules extend from the JSR deep into and throughout the cell as an irregularly dispersed network. The SR occupies 1% of the cell volume. A few, small (0.1–1.0 μm) unmyelinated nerves are present, but no neuromuscular junctions were seen. The auricles have fewer and smaller myocytes than the ventricle. The auricles also contain podocytes with pedicels having 20–35 nm slits and containing sieve‐like projections. The morphology of the Geukensia heart is similar to that of other bivalves.
Foot of two‐toed sloths: Its anatomy and potential uses relative to size of support
Authors: Mendel Frank C.
Published: February 2005

Feet of two‐toed sloths (Choloepus) are long, narrow, hook‐like appendages with only three functional digits, numbers II, III, and IV; Rays I and V are represented by metatarsals. Proximal phalanges of complete digits are little more than proximal and distal articulating surfaces. All interphalangeal joints are restricted, by interlocking surfaces, to flexion and extension. Ankle and transverse tarsal joints, however, allow extreme flexion and inversion of foot. Powerful digital flexion is augmented by several muscles from extensor compartment of leg. Intrinsic foot musculature is reduced to flexors and extensors but these, with the exception of lumbricals, are large and well developed. Choloepus uses its feet much like hooks with distal phalanges and covering claws forming the “hook” element. These hook‐like appendages are seemingly best suited for supports less than 50 mm in diameter suggesting that two‐toed sloths may prefer supports of this size in their natural habitat.
Ultrastructural localization of glucose‐6‐phosphatase and alkaline phosphatase in the vaginal epithelium of rat
Authors: Kang Yuan‐Hsu , West William L.
Published: February 2005

The effect of ovarian hormones on the activities of glucose‐6‐phosphatase and alkaline phosphatase in the vaginal epithelium was studied in immature and ovariectomized rats, using ultracytochemical techniques. Comparative studies were done on normal rats at the luteal phase and on day 14 of pregnancy.

Various vaginal cells show different degrees of response to progesterone and diethylstilbestrol (DES) with regard to glucose‐6‐phosphatase activity. Intense glucose‐6‐phosphatase activity was observed in the cisternae of granular endoplasmic reticulum (rER), Golgi saccules and vesicles, and nuclear envelope of both basal cells and stromal cells of progesterone treated rats, whereas in the basal cells and stromal cells of DES‐treated and control animals the enzyme was totally lacking. Detectable glucose‐6‐phosphatase activity was also observed, however, in the rER cisternae and Golgic complex of keratohyalin‐secreting squamous intermediate cells of the vaginal epithelium of DES‐treated rats. Alkaline phosphatase was observed in the plasma membranes of various cell types of vaginal epithelium in the normal, progesterone‐, and DES‐treated rats, Alkaline phosphatase was also found on the limiting membranes of secretory granules of mucocytes in animals at the luteal phase and during pregnancy. DES and progesterone in the doses used did not affect alkaline phosphatase activity in the rat vagina. Overall, progesterone enhances glucose‐6‐phosphatase activity in basal cells of the rat vagina prior to completion of mucification. Alkaline phosphatase was found in all cells involved in mucin secretion.
Rosette glands in the gills of the grass shrimp, Palaemonetes pugio. I. Comparative morphology, cyclical activity, and innervation
Authors: Doughtie Daniel G. , Rao K. Ranga
Published: February 2005

Two types of exocrine rosette glands (called type A and type B), located in the gill axes of the grass shrimp Palaemonetes pugio, are described. The type A glands are embedded within the longitudinal median septum of the gill axes, whereas the type B glands typically project into the efferent hemolymph channels of the gill axes. Although both glands have certain common characteristics (i.e., a variable number of radially arranged secretory cells, a central intercalary cell, and a canal cell that forms the cuticular ductule leading to the branchial surface), they differ in the following respects. The type B gland is innervated, but the type A gland is not; axonal processes, containing both granular (ca. 900–1300 Å) and agranular (ca. 450–640 Å) vesicles, occur at a juncture between adjacent secretory cells and the central cell of the type B gland. The secretory cells of type A and type B glands differ in their synthetic potential and membrane specializations. These differences are more pronounced in well‐developed, mature glands, most frequently encountered in larger (24–28 mm, total length) grass shrimp, than in the underdeveloped, immature glands that are most abundant in smaller (14–18 mm, total length) grass shrimp. Thus, in mature glands, the secretory cells of the type A rosette glands are characterized by extensive RER, abundant Golgi, and numerous secretory granules, whereas the secretory cells of the type B gland are characterized by extensively infolded and interdigitated basal plasmalemmas and by the presence of numerous mitochondria. In general, both types of glands exhibit increased secretory activity soon after ecdysis. The central and canal cells in both glands seem to have a role in the modification of the secreted materials. The possible functions assigned to the type A gland and the type B gland include phenol‐oxidase secretion and osmoregulation, respectively.