bluuebunny/crossref_metadata_2025 huggingface dataset:
Two sperm types in the spermatozeugmata of Tubifex tubifex (annelida, oligochaeta)
Authors: Braidotti Paola , Ferraguti Marco
Published: February 2005

The spermatozeugmata (sperm bundles lacking a distinct wall) from the spermathecae of Tubifex tubifex are composed of two different zones: an internal axial cylinder containing conventional spermatozoa and an external cortex composed of modified spermatozoa, tightly packed together. The conventional spermatozoa conform to the classical clitellate scheme: very long and thin with a complex acrosome, a filiform nucleus, small mitochondria, and a flagellum with Y links and β glycogen granules as accessory structures. The modified spermatozoa show “empty” acrosomes, degenerating nuclei, and tails which contain γ glycogen granules. The tails are helically wound around the spermatozeugma and are connected to each other by junctional complexes. The tips of the cortical tails are free and move with a metachronal wave. The presence of two sperm types in tubificids is discussed and a protective function for the modified cortical spermatozoa is proposed.
Morphometric studies on tenuissimus muscle spindles in the cat
Authors: Kucera Jan
Published: February 2005

Muscle spindles were studied histochemically in serial transverse sections of 42 cat tenussimus muscle specimens. Staining for myofibrillar adenosine triphosphatase was employed to identify nuclear bag1, nuclear bag2, and nuclear chain intrafusal muscle fibers. The nuclear chain fibers were further subdivided into three categories according to their polar length and the intensity of their staining for nicotinamide adenine dinucleotide tetrazolium reductase. A total of 430 spindle poles were surveyed. The mean spindle content of bag1, bag2, and chain fibers was established. The mean polar length of intrafusal fibers as well as that of the intracapsular and extracapsular spindle regions was determined. A cholinesterase (ChE) staining technique was used to demonstrate the termination sites of motor axons along intrafusal fibers. Two types of circumscribed ChE deposits, the “rim” and the “plate,” occurred on the fibers. The nuclear chain fibers usually carried both the ChE rims and plates, while most nuclear bag fibers displayed only the plates. The ChE plates were assessed in term of their appearance, staining intensity, length, and location along the fibers. The mean number of ChE plates found along the fibers was established for each of the various intrafusal fiber types.

These histochemical observations are discussed with regard to the current concepts of cat spindle morphology and motor innervation. The results suggest a degree of predictability in the spindle fiber content and in the distribution of motor nerve terminals along intrafusal muscle fibers, at least in the tenuissimus muscle.
The organization of the octavolateralis area in actinopterygian fishes: A new interpretation
Authors: McCormick Catherine A.
Published: February 2005

The octavolateralis area of actinopterygian fishes can be subdivided into a dorsal lateralis area composed of first‐order lateral line nuclei, and a ventral octavus area composed of nuclei receiving first‐order input from the eighth nerve. Three patterns of organization of the lateralis area are recognized in the present study. The organization of this area in polypteriforms and chondrosteans is similar to that in chondrichthyans. On the basis of recent studies in chondrichthyans (McCready and Boord, '76; Boord and Campbell, '77; Bodznick and Northcutt, '80), it is hypothesized that this pattern reflects the subdivision of the lateral line system into mechanoreceptive and electroreceptive portions. As petromyzontid agnathans also share this pattern of organization, it is hypothesized that they are elecroreceptive. The lateralis area of holosteans and nonelectroreceptive teleosts exhibits a second organizational pattern that is hypothesized to reflect the loss of the electroreceptive portion of the lateral line system; it is suggested that electroreception was lost sometime between the chondrostean and teleostean radiations. Each group of electroreceptive teleosts is believed to have evolved electroreception independently (Bullock, '74), a situation that is reflected centrally by a third organizational pattern within the lateralis area, which is distinctly different from that of early radiations of electroreceptive fishes.

The octavus area of actinopterygians exhibits two patterns of organization–that of polypteriforms, chondrosteans, and holosteans, and that of teleosts. The functional significance of these patterns has yet to be elucidated.
Development of the embryonic chick phagocytic system: Intraembryonic erythrophagocytosis induced by phenylhydrazine
Authors: Sorrell J. Michael , Weiss Leon
Published: February 2005

The intraembryonic reticuloendothelial response to phenylhydrazine‐induced hemolytic anemia was studied embryonic chicks (days 13–16) by light and electron microscopy and histochemical and biochemical assays for acid phosphatase. Phenylhydrazine was given on day 13 and tissue taken at 2, 5, and 10 h and at 1, 2, and 3 days after injections. The response varied in the three major reticuloendothelial organs. The spleen first demonstrated an increase in erythrophagocytosis that was accompanied by increased acid phosphatase levels. Erythrophagocytosis occurred primarily in the red pulp resulting in increased numbers of macrophages, increased size of macrophages, and retention of erythrocytes, which together combined to enlarge the spleens. By 2 days after phenylhydrazine injection, greatly enlarged macrophages began to migrate into the venous system, where some erythrophagocytosis continued to occur. The liver was also a major erythroclastic organ in which Kupffer cells became increasingly erythrophagocytic. However, erythrophagocytosis began later than in the spleen, and as measured by acid phosphatase levels, the liver was not as effective in removing damaged erythroid cells. Marrow erythrophagocytosis was only slightly enhanced; however, the marrow responded by increasing its production of red blood cells. Thus, the intraembryonic reticuloendothelial organs of the embryonic chick responded to phenylhydrazine‐induced hemolytic anemia in much the same manner as might be expected of the adult bird.
Innervation and structure of mouth part sensilla in females of the black fly Simulium venustum (Diptera: Simuliidae)
Authors: Sutcliffe James F. , McIver Susan B.
Published: February 2005

Associated with the mouth parts of female Simulium venustum are 13 morphologic types of sensilla: four on the labium, seven on the labrum, one in the cibarium, and one on the genal process to which the mandibles articulate. Seven types are probably sensitive only to mechanicla cues and three only to chemical ones, whereas the other three probably function in both modes. These sensilla likely monitor feeding‐associated chemical features of blood, sugar, and water and mechanical cues generated by the physical acts of ingestion.

Each S. venustum female has approximately 450 chemosensitive and 230 mechanosensitive neurons in the mouthpart‐associated sensilla. Both the total number of chemosensory neurons and the ratio of chemosensory to mechanosensory neurons in S. venustum are intermediate between those for blow flies, which feed on a wide variety of foodstuffs, and tsetse flies, exclusive blood‐feeders. These differences may be related to whether determination of acceptability of a potential food source occurs at the site of feeding and is dependent upon simultaneous sensitivity to many chemical cues, as in blow flies, or is the result of a complex stimulus chain composed of all host‐location steps and culminating with the detection of but a few phagostimulants in the food itself, as in blood‐feeders.
Morphology of the aedeagal gland of the male mealworm beetle (Tenebrio molitor L.)
Authors: Dailey Patrick J. , Happ George M.
Published: February 2005

The aedeagal gland of male Tenebrio molitor consists of numerous acini containing several secretory units (organules) of three epithelial cells in series. The distal cortical cell and intermediate cell are secretory cells. Secretory products are passed into microvilli‐lined extracellular reservoirs. From these storage areas products flow through minute canaliculi and into the efferent ductule. Canaliculi, cuticular trabeculae, and fibrillar material are characteristic features of the efferent ductules within the extracellular reservoirs of secretory cells. After passing from the secretory cells, the efferent ductule penetrates the basal ductule cell. The thin epicuticle that comprises the wall of the ductule is confluent with the epicuticle of the cuticular sheath forming the wall of the genital pocket. Secretory products flow from the cortical cell ductule into the intermediate cell and eventually empty into the genital pocket. A chemical reaction apparently takes place in the intermediate cell ductule, resulting in a frothy secretion product. When released from the ductule, this frothy product forms a foam‐like layer that coats the inner wall of the genital pocket. Ultrastructural and probable functional aspects of this gland are described and discussed.
Structure and evolution of tetraodontoid teeth: An autoradiographic study (pisces, Tetraodontiformes)
Authors: Andreucci Roberto D. , Britski Heraldo A. , Carneiro José
Published: February 2005

For years teeth of tetraodontoid fishes generally have been considered coalescent even though “coalescence,” which also is found in fishes of other families, has never been well defined. This paper deals with some aspects of coalescence of the teeth in tetraodontoids and attempts to define this condition. The sites of osteodentinogenesis and the mechanisms by which hard tissues are formed, reabsorbed, and abraded during feeding were analyzed from semiserial decalcified sections and from ground sections, as well as from autoradiographs of the premaxilla and dentary bones of Sphoeroides greeleyi. The observations reported here, taken together with other data we have obtained on members of the Tetraodontoidei, permit clear definitions of “tooth” and “supporting bone,” and consequently the structural meaning of coalescence. From these data we hypothesize how coalesced masticatory structures may have evolved in this group.
Fine structure of maxillary sensilla of larval Toxorhynchites brevipalpis (Diptera: Culicidae) with comments on the role of sensilla in behavior
Authors: McIver Susan , Siemicki Roman
Published: February 2005

Each maxilla of fourth instar Toxorhynchites brevipalpis bears nine sensilla: Four are located at the tip of the maxillary palp and five on the maxillary body. At the palp tip are three tapered pegs on bulbous bases (MS1, MS2, MS6) that are innervated by four, two, and two neurons, respectively, and probably function in chemoreception. Also at the palp tip is a sturdy, cuticular rod with a lumen (MS5) that opens distally to the exterior. The proximal end of the rod is closed by a cuticular base to which a single unbranched dendrite containing only a few microtubules is attached. The function of MS5 is enigmatic; possibilities include mechanoreception and detection of infrared radiation.

On the maxillary body are two tapered pegs on a common bulbous base (GS1, GS2) that are each innervated by three neurons, and probably are chemosensory. Three setae also occur on the maxillary body. They arise from prominent sockets and are each innervated by a neuron terminating at the hair base as a tubular body, a characteristic of cuticular mechanosensilla.

The maxillary sensilla are innervated by a total of 18 neurons: 14 are probably chemosensory, three mechanosensory, and one is of unknown function. These results, combined with those from a previous study on antennal sensilla (Jez and McIver, '80), indicate that the mechanosensitive neurons of the antennae and maxillae are a relatively small percentage of the total mechanosensilla on the entire larva. In contrast the chemosensitive neurons of the antennae and maxillae provide most of the information about the chemical environment of the larva.

T. brevipalpis has three less than the maximum of seven maxillary palpal sensilla found in larval mosquitoes so far studied. This difference may reflect a lesser need for sensory information about the acceptability of potential food in predators compared to browsers and filter‐feeders.
Intraendodermal and intramesenteric migration of anuran amphibian germ cells: Transmission and scanning electron microscopy
Authors: Delbos Martine , Gipouloux Jean‐Daniel , Guennoun Samira
Published: February 2005

Primordial germ cells (PGCs) from the dorsal side of midgut endoderm and from within the dorsal mesentery were examined by transmission and scanning electron microscopy. During migration of these cells, lamellipodia and filopodia, develop in a polarized pattern. Large amounts of extracellular material accumulate around the lamellipodia at the leading end of a migrating cell. It is suggested that the polarized pseudopodia function in conjunction with extracellular matrix as the means by which PGCs move en route to gonadal ridges.
Terminal degeneration in the mediodorsal cerebral cortex of the lizard Agama agama: Light and electron microscopy
Authors: Wouterlood F. G. , Alones V. E. , Elprana D. , Lohman A. H. M.
Published: February 2005

The degeneration of axon terminals in the small‐celled part of the mediodorsal cortex (sMDC) of the lizard Agama agama has been studied after lesions in the dorsal cortex at various survival periods. The Fink‐Heimer stain was used to map and demonstrate terminal degeneration with the light and electron microscope. Electron microscopy was used to identify and describe degenerating boutons ultrastructurally. One sham‐operated and three unoperated animals served as controls. Between 6 and 21 days postsurgically, degenerating terminals can be seen through 80% of the superficial plexiform layer, the zone adjacent to the cellular layer remaining free of degeneration. Swelling of dendrites in the outer part of the superficial plexiform layer and increased numbers of vacuolar invaginations, both present at short (24 hr–6 days; peak at 48–54 hr) survival periods, can be regarded as reaction to the surgical trauma. Degeneration of axon terminals takes three forms, all of the electron‐dense type: gray boutons, degenerating bouton‐dendritic spine complexes surrounded or engulfed by glia, and degeneration debris inside glial processes. Several forms of terminal degeneration occur concomitantly at any short (3–12 days) survival time. At longer survival times (15–21 days) only debris is present. From 6 days on, considerable numbers of degenerating structures are present, but the majority of degenerating boutons and debris are associated with reactive glia rather than with dendrites. From these observations it is concluded that in this lizard application of the combined degeneration‐Golgi‐EM technique would probably lead to little success. Electron microscopy of Fink‐Heimer‐stained sections suggests that degenerating bouton‐dendritic spine complexes and degeneration debris accumulate silver particles, whereas gray boutons do not.
Cerebellar afferents to paramedian lobule from the trigeminal complex in Tupaia glis: A horseradish peroxidase (HRP) study
Authors: Patrick G. W. , Haines D. E.
Published: February 2005

Projections from the trigeminal complex to paramedian lobule (PML) were studied in the tree shrew (Tupaia glis) by means of retrograde transport of horseradish peroxidase (HRP). Neurons which project to both dorsal and ventral folia of PML are located primarily in those areas of the trigeminal nuclear complex interpreted as nucleus interpolaris (Vi) and caudal areas of the nucleus oralis (Vo). The majority of HRP‐labeled neurons lie in ventral and ventrolateral regions of Vi/Vo. No HRP‐reactive cells are present in the principal (Vp), mesencephalic, or motor nuclei nor in nucleus caudalis or rostral portions of oralis. The majority of trigeminocerebellar (TC) cells are found in ipsilateral Vi; however, sparse numbers of labeled somata are present in this subnucleus on the contralateral side. Within Vi/Vo, small fusiform and medium‐ and large‐sized multipolar neurons contain HRP‐reaction product. Large multipolar cells are found primarily in ventrolateral portions of Vi/Vo, while medium and small neurons are scattered throughout the ventral half of the nucleus. Small‐sized neurons are also present dorsally within Vi/Vo. Axons of labeled TC cells course laterally through the spinal trigeminal tract, enter medial aspects of the restiform body, and arch dorsally into the cerebellum.
The early embryonic development of the primitive moth, Neomicropteryx nipponensis lssiki (lepidoptera, micropterygidae)
Authors: Kobayashi Yukimasa , Ando Hiroshi
Published: February 2005

This paper describes the early embryonic development of Neomicropteryx nipponensis from oviposition to the formation of the inner layer. Newly laid eggs are covered with many hygroscopic, gelatinous masses. The chorion is composed of a porous, spongy exochorion of variable thickness and of a thin endochorion. The eggs have a very thin periplasm and contain large amounts of yolk made of proteid and fatty yolk droplets. The processes of maturation division, fertilization, and cleavage are similar to those commonly found in lepidopteran eggs. The blastoderm of Neomicropteryx is very thin in comparison with that of other lepidopteran eggs. The small circular germ disk is formed on the ventral egg surface. It then invaginates deeply into the yolk to form a sac‐shaped germ rudiment. The formation of the germ rudiment and of the embryonic membranes resembles that of swift moths, Endoclita (suborder Monotrysia) and of the caddisfly, Stenopsyche (Trichoptera), but differs from that of ditrysian Lepidoptera. As in other lepidopteran insects, the formation of the inner layer begins after completion of the germ band, which has a bilobed protocephalon and a slender protocorm. Unlike the situation in most lepidopteran eggs, yolk segmentation does not occur in N. nipponensis. During formation of the germ band, hydropyle cells are formed in the dorso‐posterior region of the serosa; these are here reported for the first time in the eggs of holometabolan insects.
Abnormal differentiation of selected nuclear centers in the brain of a duck embryo associated with partial duplication of the primitive streak
Authors: Narayanan C. H. , Narayanan Y.
Published: February 2005

In a control set of duck embryos, and abnormal duck embryo of 16 days incubation was found which had two beaks as the only outward sign of duplication. The beaks were of equal size, each with upper and lower bills. Billclapping movements were absent. The embryo had two normal eyes placed one on either side of the head, and the rest of the body was normal in external appearance. Sections through the head revealed further duplication of the fore‐, mid‐, and hindbrain divisions. The medial half of each of the embryonic brain divisions, however, was greatly reduced. Two additional optic primordia were also noticed in sections, each of which was reduced to a mass of tissue representing a lens and a much‐folded pigment epithelium. The orbital tissues associated with the rudimentary eyes were greatly disorganized. Abnormal differentiation associated with duplication of the brain divisions was determined by cell counts in selected nuclear centers. Cell numbers in each case appeared to be remarkably proportional to the size of the innervation field. Our data, based on cell counts in the nuclear centers chosen for this study in the abnormal embryo and normal control embryos of the same age, are consistent with the hypothesis that cell survival in related parts of the nervous system may be regulated by their peripheral field of innervation.
Ultrastrucuture of the fat body of the reproductive pair in higher termites
Authors: Han Sun Heat , Bordereau Christian
Published: February 2005

The fine structure of the fat body of the higher termite king and queen has been studied both in species with (Macrotermes bellicosus, M. subhyalinus) and without (Cubitermes fungifaber) tracheal rosettes. There is a very pronounced sexual dimorphism. The adipocytes of the queen are highly specialized for protein synthesis and secretion; they store only a small quantity of reserves. The adipocytes of the king are not specialized in protein synthesis, but accumulate large amounts of reserve substances. The previously proposed different functions of the termite queen's fat body are discussed; it appears to be mainly concerned with vitellogenesis.
The sensory systems and feeding behavior of leafhoppers. I. The aster leafhopper, Macrosteles fascifrons stål (homoptera, cicadellidae)
Authors: Backus Elaine A. , McLean Donald L.
Published: February 2005

The ultrastructure of the sensilla, and other structures, within the stylets and precibarium of Macrosteles fascifrons were examined by transmission and scanning electron microscopy. Precibarium is a new term, defined here, for the canal that precedes the cibarium inside the leafhopper head. Within the precibarium are found 20 chemosensilla and a previously undescribed structure, the precibarial valve. Twelve mechanosensilla, three in each stylet, are found within the maxillary and mandibular stylets. The relationship between all of these structures and feeding by the insect is detailed in a feeding mechanism hypothesis. It is concluded that leafhoppers (and probably all homopterans) utilize the precibarial chemosensilla alone for gustatory discrimination, the stylet sensilla for proprioception, and the precibarial valve for regulation of fluid uptake and compartmentalization of the sensilla.
Development of the crayfish retina: A light and electron microscopic study
Authors: Hafner G. S. , Tokarski T. , Hammond‐Soltis G.
Published: February 2005

The development of the crayfish retina was examined in embryos and first, second and third instars with both and light and electron microscope. Light microscopic observations indicate that differentiation begins at the posterior portion of the optic disc and progresses in an anterior direction. Development of screening pigment, dioptric elements, and rhabdoms all parallel this posterior to anterior gradient in the retina. Tracer studies in early embryos reveal that the retina is separated from the proximal neuropil regions by a distinct vascular space. This observation suggests that the source of new cells for the retina may not be the more proximal cell proliferation zone as previously indicated. It is proposed that mitotic activity within the retina and/or differentiation of cells from the anterior surface layer of the eye may be sources for addition of new cells to the retina. Proto‐ommatidial clusters of seven retinula cells occur very early at the posterior region of the embryonic retina. Initially the receptor cells extend throughout the entire thickness of the retina, but later they withdraw from beneath the cornea to occupy only the proximal portion of the retina. Microvilli of the rhabdom arise from the centrally opposed membranes of the retinula cells in each cell cluster. Each new microvillus contains a core of fine filaments which extend out into the cytoplasm at its base. As development of the microvilli continues, the core filaments appear to be lost or altered, but the cytoplasmic bundles at the base of the microvilli persist.
Pattern development in palleal buds of botryllid ascidians: Relation between parent and its buds in their body axes
Authors: Kawamura Kazuo , Watanabe Hiroshi
Published: February 2005

In order to determine how the zooid pattern (normal or reversed bilateral asymmetry) is transmitted through asexual reproduction in botryllid ascidians, the axial relationship between a zooid and its palleal buds was observed in Symplegmo reptans, Metandrocarpa uedai, Polyandrocarpa misakiensis, and P. stolonifera. The bud axes developed in harmony with the parent axes, with both normal and reversed body patterns, so that (1) when buds are given off from the right (left) side of the parent, their distal side becomes the right (left) in the future zooids (coincidence of the anteroposterior axis), (2) the free surface of the developing buds, like the parent, becomes dorsal (the coincidence of dorsoventral axis), and (3) the heart (gut loop), which is an organ representing the bilateral asymmetry, arises on the distal side of the developing buds, when the buds are derived from the side where the parent heart (gut loop) was situated (coincidence of the transverse axis). This shows that the bud develops as if it knew the position on the parent lateral wall from which it has arisen, a phenomenon referred to as the parental lateral effect.
Homology and causes
Authors: Van Valen Leigh M.
Published: February 2005

Homology is resemblance caused by a continuity of information. In biology it is a unified developmental phenomenon. Homologies among and within individuals intergrade in several ways, so historical homology cannot be separated sharply from repetitive homology. Nevertheless, the consequences of historical and repetitive homologies can be mutually contradictory. A detailed discussion of the rise and fall of the “premolar‐analogy” theory of homologies of mammalian molar‐tooth cusps exemplifies such a contradiction. All other hypotheses of historical homology which are based on repetitive homology, such as the foliar theory of the flower considered phyletically, are suspect.
Sorbic acid‐induced differences in the ultrastructural development of oocytes in the microbially ectosymbiotic female of Xyleborus ferrugineus (fabr.) (coleoptera, scolytidae)
Authors: Chu H. M. , Norris D. M. , Rao K. D. P.
Published: February 2005

The ovaries of the beetle Xyleborus ferrugineus reared on standard sawdust diet with an without 0.08% sorbic acid added were examined for differences in ultrastructural development of the oocytes. Indications of vigorous yolk deposition are an extensive rough‐surfaced endoplasmic reticulum (RER), numerous electron‐dense secretory vesicles and a prominent nucleus in associated follice cells, and extremely electron‐opaque material in the interfollicular cell spaces and the perioocytic area. After 6 days of feeding without added sorbic acid, a mature terminal oocyte is present in one of the two ovaries. This terminal oocyte at this mature stage contains yolk spheres and lipid bodies. However, the most mature oocyte in beetles reared on the standard sawdust diet to which 0.08% sorbic acid was added remained at a previtellogenic stage after 6 days of feeding. Titers of ecdysone in 6‐day‐old adult females reared on standard sawdust without and with 0.08% sorbic acid added were 534.64 ± 20.93 S.D. pg/mg and 39.94 ± 14.71 S.D. pg/mg body weight, respectively.
Comparative study of hemocytes and associated cells of some medically important dipterans
Authors: Kaaya Godwin P. , Ratcliffe Norman A.
Published: February 2005

The aim of this work is to study, characterize, and compare different morphological types of hemocytes of Glossina austeni, G. morsitans, Calliphora erythrocephala, Stomoxys calcitrans, Lucilia sericata, Aedes aegypti, and Culex quinquefasciatus. This information is intended to provide a basis for future studies of the cellular defense mechanisms of these dipterans.

Seven morphological types of hemocytes were identified by phase‐contrast optics: prohemocytes, plasmatocytes, thrombocytoids, granulocytes, adipohemocytes, oenocytoids, and spindle cells of various sizes. Adipohemocytes are difficult to distinguish from both fat body cells and granulocytes. All seven cell types are not present in every species. For example, thrombocytoids and spindle cells were not found in A. aegypti or C. quinquefasciatus, and oenocytoids were observed only in A. aegypti, C. quinquefasciatus, and in C. erythrocephala.

In addition to the hemocytes, fat body cells and nephrocytes are also freely present in the hemolymph of some species but may have gained access to the blood during the bleeding process.

With electron microscopy and with thick plastic sections of G. austeni hemolymph, only nephrocytes, plasmatocytes, granulocytes, and spindle cells were identified wth any certainty, and the large spindle cells are morphologically very different from those found in the other dipterans. They are rigid cells supported by microtubules running throughout their entire length. These hemocytes are present in large numbers only in newly emerged flies, they are absent in larvae and young pupae, and are rare in old adults. Their disappearance from the hemolymph of newly emerged Glossiua appears to be a result of phagocytosis by the plasmatocytes.
The body surface of Branchiobdella pentodonta whit. (annelida, oligochaeta) examined by scanning microscopy
Authors: Farnesi Rosalba M. , Marinelli Marinella , Tei Simonetta , Vagnetti Daniela
Published: February 2005

The body of Branchiobdella pentodonta is uniformly covered with cuticular microvilli and abounds in sensory receptors. Muscle attachments are clearly visible both on the prostomium and trunk (11 segments). The mouth opening, oriented dorsally with respect to the adhesive sucker disk, possesses papillae with apical notches.

On all trunk segments except the last three, which form the posterior sucker, mucous gland pores are evident. The nephridia open on the 3rd and 8th segments. On the more turgid sexual segments (5th, 6th, 7th) the spermathecal, atrial, and oviductal openings are seen. The 6th and 7th also contain the clitellum gland pores.

The posterior sucker is delimited by a thick ring and the adhesive disk, and like the anterior disk is completely covered with the gland complex pores. The anal opening is on the 9th segment dorsal to the sucker. Based on these studies, we believe that the family Branchiobdellidae should be removed from the Oligochaeta and raised in rank to form a separate group.
Cell movements in a living mammalian tissue: Long‐term observation of individual cells in wounded corneal endothelia of cats
Authors: Honda H. , Ogita Y. , Higuchi S. , Kani K.
Published: February 2005

Although the cells in tissues are known to be motile under special conditions (e.g., during tissue turnover or wound healing), there are not many reports that polygonal cells covering an area without leaving any gaps are also capable of movement. In the present study, cell movements (cell shifting and rearrangement) in a living mammalian eye tissue were documented by identifying and locating individual cells over intervals as long as 100 days. Cat corneal endothelium, a monolayered cell sheet, was wounded by removing a small number (about 180) of endothelial cells from the internal lining of the cornea. Healing of the wounded tissue was observed with a wide‐view specular microscope applied to the outer surface of the cornea, enabling us to identify individual cells for as long as two to three months.

Cells surrounding the wound underwent areal enlargement, elongated toward the wound, and shifted to cover the wound surface. During days 4–7, cells became rearranged by changing neighbors in such a way that they retained their enlarged size but recovered their non‐elongated, original shape. This pattern of cell rearrangement was interpreted by a computer simulation which assumed that cells shorten their boundary length while maintaining contacts with contiguous cells. After day 7, the enlarged cells adjacent to the wounded area gradually contracted and pulled surrounding cells toward the wounded area. These movements were followed by a temporary halt in cell shifting, then by a recovery of shifting and cell elongation. These movements are interpreted as a result of the contractility of endothelial cell microfilaments.
Seasonal changes in the pituitary gland of the feral hawaiian mongoose (Herpestes auropunctatus)
Authors: Nelson Marita L. , Inao Jan
Published: February 2005

The Hawaiian mongoose (Herpestes auropunctatus) is a seasonally breeding mammal whose pituitary gland resembles that of other Viverridae. Certain features, such as a prominent pars tuberalis interna and a double‐layered pars intermedia forming a cup for the neurohypophysis, are unique.

With the light microscope, five different cell types can be recognized in the pars distalis after staining with periodic acid‐Schiff (PAS)‐orange G. Two types of acidophils are seen, a small yellow‐staining cell and a large angular orange cell. Two basophilic cells are also seen, one with fine PAS‐positive cytoplasmic granules and the other with coarse PAS‐positive granules in the cytoplasm. The last cell type seen is the chromophobe. Differential cell counts indicated an altered distribution of chromophils in the ventral pars distalis of the female mongoose with changing season and reproductive status, but the most striking change was a decreased percentage of basophils in the pars distalis during the nonbreeding season.
Novel surface specialization on a sea anemone egg: “Spires” of actin‐filled microvilli
Authors: Schroeder Thomas E.
Published: February 2005

The ultrastructure of the “spiny” surface of Tealia crassicornis eggs is examined in detail by scanning and transmission electron microscopy in order to understand its function. Long microvilli are clustered together in spiral aggregates of 50–75 microvilli called “spires.” There are about 15,000 spires per egg. Dense bundles of microfilaments making up the cores of these microvilli are shown to be composed of actin by staining with the fluorescent dye nitrobenzoxadiazole (NBD)‐phallacidin. It is postulated that the bundles of actin and the spires of microvilli are stiff and provide reinforcement to the egg surface. Such postulated properties would provide physical protection for these large eggs which, unlike the eggs of most invertebrates, appear to lack all extracellular investing coats.
Fiber composition of the superior rectus extraocular muscle of the rhesus macaque
Authors: Pachter Bruce R.
Published: February 2005

The fiber composition of the superior rectus extraocular muscle of adult rhesus monkeys (Macaca mulatta) was examined in serial sections by light and electron microscopy as well as morphometry. Analyses allowed separation of singly versus multiply innervated fibers, and disclosed the morphology of these fibers and their topographical distribution within the muscle. Six morphologically distinct fiber types were found. The global layer of the muscle contains three singly innervated fibers (SIFs) and one multiply innervated fiber (MIF). The overlying orbital surface layer contains one SIF and one MIF, both showing morphological variation along their lenght. The MIFs of the orbital surface layer had not only multiple, relatively superficial endings along their length, but also endplatelike junctions in which the axonal terminals lie within synaptic clefts. These endplatelike junctions were confined to that region of the MIFs that had a morphology typical of “twitch” fibers; away from this region these MIFs had a morphology characteristic of “tonic” fibers. In contrast, the global MIFs showed constant morphology, and did not exhibit endplatelike endings.
The leukocytic organ of the megascolecid earthworm, Amynthas diffringens (annelida, oligochaeta)
Authors: Friedman Marc M. , Weiss Leon
Published: February 2005

Leukocytic organs of Amynthas diffringens are aggregations of leukocytes contained within a smooth muscle and stromal cell framework suspended in the coelom. Elongate processes of stromal cells subdivide each organ into numerous cell‐filled compartments and are perforated by 130‐nm pores that may permit the exchange of humoral substances between compartments, or between the organ and the surrounding coelomic fluid.

We divide leukocytes within the organs into four morphotypes. Phagocytic leukocytes have many lysosomelike vesicles and may possess phagosomes. Mature types I, II, and III granulocytic leukocytes share certain features but are readily distinguished by cell shape and by the size, shape, and electron density of the cytoplasmic inclusions. Immature as well as mature phagocytes and granulocytes occur within these organs, suggesting that they are sites of leukocyte maturation and storage. Concentrations of leukocytes within the organs result in extensive cell to cell contact, especially within islets and tightly packed cords. Phagocytosis of cell debris occurs throughout the organs.

Immature stages of the four morphotypes are difficult to distinguish even at high magnification, raising the possibility that they may originate from a common precursor. Our inability to observe mitoses or to detect lymphocytelike stem cells suggests that immature leukocytes migrate to the organs via coelomic fluid from as yet unidentified primary sites of production.
Structure and cytochemistry of the silk glands of the mygalomorph spider Antrodiaetus unicolor (araneae, antrodiaetidae)
Authors: Palmer Jacqueline M. , Coyle Frederick A. , Harrison Frederick W.
Published: February 2005

Dissection and a variety of absorption and fluorescent cytochemical methods have demonstrated that Antrodiaetus unicolor females have only one type of silk gland and spigot and, consequently, the simplest silk production system of any spider yet investigated histochemically. The small spherical to pear‐shaped glands are grouped into four clusters, each cluster serving one of the four spinnerets. The spigots are long, slender, and slightly bent distally. Although all gland cells are structurally similar, each gland simultaneously produces two different secretory products, the secretion of the distal hemisphere being rich in basic protein and sulfhydryl groups, and the proximal hemisphere secretion being an acidic protein containing a high concentration of histochemically demonstrable C‐terminal carboxyl groups. The two products remain segregated as they pass through the duct, where the acidic protein forms a thin outer layer around a core of basic protein. It is suggested that this segregation may persist in the silk strand after it exits from the spigot and that the outer acidic protein may be an adhesive agent.
Comparative aspects of brain organization of an african “wave” electric fish, Gymnarchus niloticus
Authors: Bass Andrew H. , Hopkins Carl D.
Published: February 2005

Gymnarchus niloticus, one of the less‐well‐known electroreceptive teleost fishes, is the only African mormyriform fish with a wavelike or tone electric organ discharge. For Gymnarchus, this is the first detailed description of the lateral line lobe, vestibulolateral lobe, cerebellum, and midbrain torus semicircularis—central electrosensory structures. Brain organization in Gymnarchus closely resembles that of mormyrids. In particular, the lateral line lobe is a bilateral structure with three cortical zones—ventral, dorsal, medial—and a fourth central zone of large cells. The convergent evolution of the electric sense of mormyriform and gymnotoid fish, and its central representation, is discussed.
Evolution of the vestibulolateral lobe of the cerebellum in electroreceptive and nonelectroreceptive teleosts
Authors: Bass Andrew H.
Published: February 2005

The organization of the vestibulolateral lobe of the cerebellum is described in electroreceptive and closely related nonelectroreceptive teleost fishes. The vestibulolateral lobe includes an eminentia granularis and a lobus caudalis. The eminentia granularis is a lateral line‐recipient, granule cell zone which in weakly electric fish (i.e., electroreceptive fish with an electric organ) has anterior and posterior divisions associated respectively with a mechanoreceptive medial medullary nucles and an electroreceptive lateral line lobe. A lobus caudalis includes a separate granule cell zone—the pars medialis, a molecular layer, and large Purkinje‐like cells. Compared with weakly electric mormyrids, the pars medialis is hypertrophied in weakly electric gymnotoids and electroreceptive silurids. However, the pars medialis is also hypertrophied in nonelectroreceptive teleosts, suggesting it is a granule cell zone not associated with electroreception and perhaps the lateral line system.
Evolutionary loss of a neural pathway from the nervous system of a fly (Glossina morsitans/Diptera)
Authors: King David G.
Published: February 2005

Three pairs of specialized axons found in other muscoid flies are absent in the tsetse, Glossina morsitans, which also lacks the tergotrochanteral muscle. Neither light nor electron microscopy could demonstrate any evidence for the cervical giant fiber axon, the peripherally synapsing axon, or the tergotrochanteral motor axon. The specialized characteristics of these axons must have been altered during the evolution of Glossina. This divergence of individual neurons from the more typical muscoid pattern not only demonstrates the evolutionary modification of specific identified cells; it may also provide an opportunity to study the ontogenetic determination of unique neuronal features.
A comparative ultrastructural study of the trigeminal ganglion in the rat and chicken
Authors: Sugiura Yasuo , Kitoh Junzoh , Sakai Hisashi
Published: February 2005

The neurons of the trigeminal ganglia of the rat and chicken were characterized by means of light microscopic, electron microscopic, and histochemical methods. Light microscopy disclosed four types of neurons, based on the characteristics of Nissl granules: (1) large neurons with diffusely distributed and very fine granules, (2) neurons containing coarse and sparsely distributed Nissl granules, (3) neurons containing dense Nissl granules of varying size, and (4) small neurons with granules concentrated peripherally. Electron microscopy allowed further definition of these four types of neurons by the length and arrangement of flattened cisterns of granular endoplasmic reticulum (gER) and the number of neurofilaments. Type 1 cells were largest, with a mean nuclear area of 139.8 ± 28.3 μm2. Type 4 cells were smallest, with a mean nuclear area of 74.6 ± 20.9 μm2. The mean nuclear areas of type 2 and 3 cells were intermediate to those of the type 1 and 4 cells. Type 3 and 4 neurons lacked neurofilaments. Four forms of Golgi apparatus were found: (1) large bent grains forming a network throughout the soma, (2) dispersed fine granular deposits, (3) fine or small granules, and (4) coarse bent deposits arranged confluently in the perinuclear zone. In some rat neurons, the concentration of acid phosphatase reaction products suggested a high enzymatic activity, whereas the chicken ganglion cells showed no such concentration. These findings are discussed and compared with the classifications of previous studies.
The ultrastructure of the atrium in the adult newt Notophthalmus viridescens (Amphibia, Salamandridae)
Authors: McDonnell Timothy J. , Oberpriller John O.
Published: February 2005

The atrial wall of Notophthalmus viridescens is 25–75 μm thick and is trabeculated sparsely. Coronary vessels are absent. The endocardial endothelium is continuous and has 50–60 nm‐wide fenestrae with diaphragms, rests on a discontinuous basal lamina and lacks occluding junctions. Cells found in the subendothelial connective tissue are xanthophores, melanophores, mast cells, fibroblasts, macrophages, and unmyelinated nerve fibers with Schwann cell investments. Epicardial mesothelial cells contain numerous 6–7 nm filaments and lamellar bodies which resemble myelin figures. Mesothelial cell junctions include maculae adhaerentes diminutae, desmosomes, and interdigitations. The epicardial connective tissue layer is more extensive than that of the endocardium, with xanthophores and melanophores rarely present and nerve fibers never observed. The myocardium consists of a mesh‐work of myocytes 3–5 cell layers thick with little intervening connective tissue. Myocytes are 6–10 μm in diameter and have two or three peripheral myofibrillae. Typical A, I, H, Z, and M bands are present with a sarcomere length of 2.5 μm. T tubules are not observed. The sarcoplasmic reticulum has subsarcolemmal dilations. The nuclear pole region contains abundant mitochondria and atrial granules, extensive Golgi, and elements of smooth and rough‐surfaced endoplasmic reticulum. Lateral intercellular junctions consisting of dense plaques, frequently continuous with Z‐line material, are common. Oblique and transversely oriented junctions consisting of primarily of fascia adhaerentes, are present. It appears that amphibian atrial myocytes more closely resemble those of the amphibian ventricle than those of the mammalian atrium. Structural differences between amphibian atrial and ventricular myocytes seem to be quantitative rather than qualitative in nature.
Morphology of neurons in the torus semicircularis of the northern leopard frog, Rana pipiens pipiens
Authors: Feng Albert S.
Published: February 2005

The neuronal morphology of the torus semicircularis of the northern leopard frog, Rana pipiens pipiens, was examined in Golgi‐impregnated material. Neurons in each of the five subdivisions of the torus semicircularis (Potter, '65a) have distinct morphologies which are characteristic of the subdivision.

Laminar nucleus neurons are mostly multipolar with spherical or ovoidal somata and smooth dendrites oriented primarily parallel and perpendicular to the cell laminae. Principal nucleus neurons have variable soma shapes with short dendrites ( < 100 μm) radiating in all directions. In the magnocellular nucleus, there are three major cell types: neurons characterized by small, spherical‐shaped somata, with short, thin, radiating dendrites and many varicosities; bi‐ or tripolar neurons with ovoidal somata, and long (100–200 μm) and smooth dendrites orienting primarily dorsoventrally and mediolaterally; and multipolar neurons with triangular‐shaped somata and very long (200–350 μm) dendrites, which are either smooth or highly spiny. Neurons in the commissural nucleus are mostly multipolar cells with ovoidal somata and beaded dendrites projecting mostly dorsally and ventrally. The subependymal midline nucleus contains mostly uni‐ or bipolar neurons with small ovoidal somata and straight, spiny dendrites.

In addition to revealing the morphological features of neurons in the torus, the counterstained material shows further cytoarchitectural organization of the principal nucleus, i.e., the presence of a circular lamellar organization. The functional significance of these anatomical features is discussed.
The mechanism of venom secretion from Duvernoy's gland of the snake Thamnophis sirtalis
Authors: Jansen David W. , Foehring Robert C.
Published: February 2005

The venom glands of snakes of the families Elapidae and Viperidae are thought to have evolved from Duvernoy's gland of colubrid ancestors. In highly venomous snakes elements of the external adductor musculature of the jaw insert fibers directly onto the capsule of the venom gland. These muscles, upon contraction, cause release of contents by increasing intraglandular pressure. In Thamnophis sirtalis, a colubrid, there is no direct connection between Duvernoy's gland and the adductor musculature. The anatomical arrangement of the gland, skull, adductor muscles, and the integument is such that contraction of the muscles may facilitate emptying of the gland. This hypothesis was tested by electrical stimulation of the muscles, which resulted in significantly greater release of secretion than elicited by controls. The results suggest a possible early step in the evolution of a more intimate association between venom glands and adductor musculature in highly venomous snakes.
Structural and functional organization of the suprapatella in two cercopithecines
Authors: Walji A. H. , Fasana F. V.
Published: February 2005

Gross and microscopic study of Cercopithecus aethiops pygerythrus and Papio cyanocephalus anubis shows that these cercopithecines have a quadriceps tendon the distal portion of which consists mostly of dense collagenous bundles with scattered fine elastic fibres most of which lie in the loose connective tissue planes within and around the tendon and around blood vessels. A distinct fibrovesicular structure, the suprapatella, lies within the tendon of the vastus intermedius above the pony patella. Histologically, this structure is characterised by interwoven bundles of collagenous fibres, among which are enmeshed large cells containing prominent nuclei surrounded by large clear spaces.

It is postulated that this structure facilitates hyperfluxion of the knee during the initial phases of springing and jumping.