bluuebunny/crossref_metadata_2025 huggingface dataset:
Avian scale development: XI. Immunoelectron microscopic localization of α and β keratins in the scutate scale
Authors: Carver Wayne E. , Sawyer Roger H.
Published: February 2005

Epithelial‐mesenchymal interactions play important roles in morphogenesis, histogenesis, and keratinization of the vertebrate integument. In the anterior metatarsal region of the chicken, morphogenesis results in the formation of distinct overlapping scutate scales. Recent studies have shown that the dermis of scutate scales is involved in the expression of the β keratin gene products, which characterize terminal differentiation of the epidermis on the outer scale surface (Sawyer et al.: Dev. Biol. 101:8–18, '84; Shames and Sawyer: Dev. Biol. 116:15–22, '86; Shames and Sawyer: In A.A. Moscona and A. Monroy (eds), R.H. Sawyer (Vol. ed): Current Topics in Developmental Biology. Vol. 22: The Molecular and Developmental Biology of Keratins. New York: Academic Press, pp. 235–253, '87). Since α and β keratins are both found in the scutate scale and are members of two different multigene families, it is important to know the precise location of these distinct keratins within the epidermis. In the present study, we have used protein A‐gold immunoelectron microscopy with antisera made against avian α and β keratins to specifically localize these keratins during development of the scutate scale to better understand the relationship between dermal cues and terminal differentiation. We find that the bundles of 3‐nm filaments, characteristic of tissues known to produce β keratins, react specifically with antiserum which recognizes β keratin polypeptides and are found in the embryonic subperiderm that covers the entire scutate scale and in the stratum intermedium and stratum corneum making up the platelike beta stratum of the outer scale surface. Secondly, we find that 8–10‐nm tonofilaments react specifically with antiserum that recognizes α keratin polypeptides and are located in the germinative basal cells and the lowermost cells of the stratum intermedium of the outer scale surface, as well as in the embryonic alpha stratum, which is lost from the outer surface of the scale at hatching. The α keratins are found throughout the epidermis of the inner surface of the scale and the hinge region. Thus, the present study further supports the hypothesis that the tissue interactions responsible for the formation of the beta stratum of scutate scales do not directly activate the synthesis of β keratins in the germinative cells but influence these cells so that they or their progeny will activate specific β keratin genes at the appropriate time and place.
Morphological changes in the oral (Buccopharyngeal) membrane in urodelan embryos: Development of the mouth opening
Authors: Takahama Hideki , Sasaki Fumie , Watanabe Kyozo
Published: February 2005

The ultrastructure of the oral (buccopharyngeal) membrane in the embryo of the urodelan, Hynobius tokyoensis, was examined by transmission (TEM) and scanning electron microscopy (SEM). The oral membrane consists of the stomodeal ectoderm and foregut endoderm, and is three to five cell layers thick at stage 24. The oral membrane gradually thickens as development proceeds. The stomodeal collar, derived from the ectoderm, is folded inward along the foregut endoderm. Tooth germs are formed partly by cells of the stomodeal collar and partly by mesenchymal cells and calcification takes place before hatching. Secretory granules, which are markers of epithelial differentiation, appear in some cells of the foregut endoderm. Within the oral membrane, the cells of the stomodeal collar become the basal cells, and the endodermal cells of the foregut become the apical cells of the future oral epithelium. Gaps are formed by the epithelial differentiation of the endodermal cells of the foregut in the oral membrane. The gaps connect with each other, with the stomodeum, and with the foregut. As a result of these events, the mouth opens at stage 43, just after hatching.
Reevaluation of the caudal skeleton of some actinopterygian fishes: II. Hiodon, Elops, and Albula
Authors: Schultze Hans‐Peter , Arratia Gloria
Published: February 2005

The vertebral centra of Hiodon, Elops, and Albula are direct perichordal ossifications (autocentra) which enclose the arcocentra as in Amia. An inner ring of ovoid cells forms in late ontogeny from the intervertebral space inside the autocentrum. The chordacentrum is reduced or completely absent in centra of adult Elops, whereas it forms an important portion of the centra in adult Hiodon. The posterior portion of the compound ural centrum 3+4+5 is partially (Hiodon) or fully formed by the chordacentrum (Elops, Albula). The haemal arches and hypurals are fused medially by cartilage or bone trabecles of the arcocentrum with the centra, even though they appear autogenous in lateral view in Elops and Albula. The composition of the caudal skeleton of fossil teleosts and the ontogeny of that of Hiodon, Elops, and Albula corroborate a one‐to‐one relationship of ural centra with these dorsal and ventral elements. The first epural (epural 1) of Elops relates to ural centrum 1, whereas the first epural (epural 2) of Hiodon and Albula relates to ural centrum 2. In Albula, the first ural centrum is formed by ural centrum 2 only. With 4 uroneurals Hiodon has the highest number within recent teleosts. Juvenile specimens of Hiodon have eight, the highest number of hypurals within recent teleosts; this is the primitive condition by comparison with other teleosts and pholidophorids. Reduction of elements in the caudal skeleton is an advanced feature as seen within elopomorphs from Elops to Albula. Such reductions and fusions occur in osteoglossomorphs also, but the lack of epurals and uroneurals separates most osteoglossomorphs (except Hiodon) from all other teleosts.
Ultrastructure of the malpighian tubules of Schistocerca gregaria
Authors: Garrett Margaret A. , Bradley Timothy J. , Meredith Joan E. , Phillips J. E.
Published: February 2005

The ultrastructure of the Malpighian tubules of the adult desert locust, Schistocerca gregaria, is described. Male and female adults possess about 233 tubules, which empty proximally into the midgut‐ileal region of the alimentary canal by way of 12 ampullae. The tubules vary from 10 mm to 23 mm in length. About one third of them are directed anteriorly, attaching distally at the caeca, while the remainder are directed posteriorly, attaching to other tubules, the rectum or large tracheal trunks adjacent to the hindgut. The Malpighian tubules from all locations examined consist of three ultrastructurally distinct regions: proximal, middle, and distal, referring to their position relative to the midgut. All cell types possess ultrastructural features characteristic of ion transporting tissue, i.e., elaboration of the basal and apical membranes and a close association of these membranes with mitochondria. The distal and proximal segments are short (1.5‐1.7 mm) and heavily tracheated, and each is composed of a single, distinct cell type. The middle region is the longest segment of the Malpighian tubule and is composed of two distinct cell types, primary and secondary. Both cell types are binucleate. The more numerous primary cells have large nuclei, contain laminate concretions in membrane‐bound vacuoles, and possess large microvilli that contain mitochondria. The secondary cells are smaller and possess smaller nuclei. The microvilli are reduced and lack mitochondria. Secondary cells do not contain laminate concretions. The possible compartmentalization of ion and fluid transport function based on segmentation in the Malpighian tubules is discussed.
Basement membrane proteoglycans and anionic sites in the fetal rat kidney during late gestation
Authors: Bakala H. , Cornet S. , Cheignon M. , Djaziri R. , Schaeverbeke J.
Published: February 2005

Proteoglycans were studied in developing rat fetal kidney using cytological and biochemical techniques. These compounds were detected with immunoperoxidase in the nephron basement membranes from the earliest stages of differentiation. In the glomerular basement membrane, immunostaining appeared as both diffuse and granular deposits, as long as this membrane consisted of loose material; however, as soon as a three‐layered membrane had formed, staining was confined to the laminae rarae as regularly arranged granules. The same pattern of staining was observed during differentiation of the basement membrane of the proximal tubule. In Bowman's capsule, immunostaining appeared as granules, which were sparsely distributed in the developing glomerulus and then regularly lined the stacked laminae when differentiation was complete. In all basement membranes, anionic sites (disclosed by polyethyleneimine) were colocated with immunostained granular diposits. Total glycosaminoglycan content gradually increased from the beginning of metanephros development to birth. During this period, the relative proportions of glycosaminoglycans changed: heparan sulfate increased and hyaluronic acid deceased as differentiation proceeded. The possible relationship between morphological observations and biochemical changes in glycosaminoglycan content is discussed.
The anatomy of the middle ear of the tinamiformes (Aves: Tinamidae)
Authors: Saiff Edward
Published: February 2005

The morphology of the middle ear region including the basicranium and quadrate of tinamous is compared among ratites and flying birds belonging to the Procellariiformes, Sphenisciformes, Pelecaniformes, and Ciconiiforms. The middle ears of tinamous and ratites share a number of important characters including absence of a separate foramen for the glossopharyngeal nerve; eustachian tube, carotid artery, and stapedial artery encased in bone; and a metotic process with vascular canals or notches. Outgroup analysis confirms these characters as synapomorphies. These data support the position that the Tinami and Ratiti form a monophyletic assemblage.
Fine structure of larval malpighian tubules and rectal sac in the tick Ornithodoros (Pavlovskyella) erraticus (Ixodoidea: Argasidae)
Authors: El Shoura Samir M.
Published: February 2005

The fine structure of the Malpighian tubules (Mts) and rectal sac (rs) is described in the larval tick Ornithodoros (Pavlovskyella) erraticus before and after feeding up to molting. Mts consist of structurally different pyramidal and cuboidal cells along the entire length of the tubule. In unfed ticks, the two types of cell are characterized by apical microvilli and a few basal membrane infoldings. The abundant pyramidal cells contain glycogen particles, lipid droplets, lysosomelike structures, and rickettsialike microorganisms. After feeding but before molting, pyramidal cells loose glycogen particles and become very dense and dramatically reduced in size. These cells are possibly involved in the formation of guanine crystalloids as an excretory product. In contrast, cuboidal cells, filled with glycogen particles, free ribosomes, and mitochondria in unfed larvae, grow steadily after feeding; their cytoplasm becomes rich in lipid droplets in addition to showing an increase in glycogen particles. Lipid and glycogen could be the source of energy required for water and ion reabsoprtion in which cuboidal cells are probably involved.

The paired‐lobe rs consists of one type of cuboidal cells with basal membrane infoldings and a brush‐border microvilli covered by a fuzzy coat of glycocalyx. These cells grow rapidly after feeding; they have functional features indicating extensive, selective reabsorption of essential components from excretory products.
The cleavage pattern in the leech Theromyzon tessulatum (Hirudinea, Glossiphoniidae)
Authors: Sandig Martin , Dohle Wolfgang
Published: February 2005

In order to evaluate the differences in the cleavage patterns of the glossiphoniid leeches Glossiphonia complanata and Theromyzon tessulatum, previously studied by Müller ('32) and Schmidt ('17, '41), the cleavage of Theromyzon tessulatum was reexamined. For the period of the first 29 hours of development embryos were observed, photographed, and serially sectioned for light microscopy at each developmental stage. The exact cell lineage until completion of teloblast formation is reported. Besides some other not previously reported features, we show that the mesoteloblast precursor cell in the glossiphoniid leeches, as probably in most Annelida, is not the cell 3D, but cell 4d formed by an additional division of cell 3D. The results further indicate that all glossiphoniid leeches likely share a common cleavage pattern, and that major differences between Glossiphonia complanata and Theromyzon tessulatum do not exist. A comparison between the cleavage patterns of some Oligochaeta and Hirudinea is made, and plesiomorphic characters in the cleavage of a clitellate ancestor species and their deviations in present day species are discussed.
Localization of serotonin‐like immunoreactivity in the eyestalk of the prawn Palaemon serratus (Crustacea, Decapoda, Natantia)
Authors: Bellon‐Humbert C. , Van Herp F.
Published: February 2005

A serotonin‐like substance in the organ of Bellonci in the eyestalks of embryos, larvae, and adults of the prawn Palaemon serratus was visualized by the use of two specific antisera against serotonin (5‐hydroxytryptamine; 5‐HT) in combination with peroxidase‐antiperoxidase (PAP). The organ of Bellonci, characterized by compact onion bodies distally and degenerating onion bodies proximally, was the only site of the serotonin‐like substance in adults, as well as during development in embryos and larvae. Variations in the content of the 5 HT analogue in the adult were detected during the molting cycle. There was more immunoreactivity in specimens fixed at night than in those fixed in daytime. Likewise, colchicine and nialamide injections enhanced the immunoreactivity of the serotonin‐like substance. Extirpations of the medulla externa X organ (MEX), a neurosecretory cell group of the optic ganglion medulla externa, produced the same effect.
Histochemistry of flight muscles in the jamaican fruit bat, Artibeus jamaicensis: Implications for motor control
Authors: Hermanson John W. , Foehring Robert C.
Published: February 2005

Two fast‐twitch fiber types are histochemically identified in the primary flight muscles of Artibeus jamaicensis. These are classified as type IIa and IIb according to an acid‐preincubation staining protocol for myosin ATPase. All fibers in the bat flight muscles exhibit relatively intense staining properties for NADH‐TR, suggesting a high oxidative capacity. The glycolytic potential of all fibers is rather low, as assessed by stains for alpha‐GPD. This two‐type histochemical profile appears to parallel biphasic electromyographic patterns observed in these muscles and leads us to propose that flight muscle histochemistry and activation are mediated by a “two‐gear” neuromuscular control system. In contrast, earlier studies on Tadarida brasiliensis demonstrate the existence of a “one‐gear” neuromuscular control system, exemplified by the presence of one fiber type. These observations are discussed with respect to the natural history and flight styles of several species.
Scanning electron microscopy of changes in epidermal structure occurring during the shedding cycle in squamate reptiles
Authors: Irish Frances J. , Williams Ernest E. , Seling Edward
Published: February 2005

Previous studies of squamate epidermal structure have focused on either histology and ultrastructure or oberhautchen surface texture as revealed by scanning electron microscopy (SEM). Using SEM data drawn from a variety of lizard taxa (primarily iguanids, but also agamids, chamaeleonids, and scincids), as well as amphisbaenians and colubrid snakes, we relate the surfaces encountered in gross dissection of squamate skin to histologically identifiable layers, and characterize their surface structure. Only the oberhautchen bears the repeating pattern of ornamentation noted by previous authors. Because the clear layer is a perfect template of the oberhautchen surface, it is the only layer with which the oberhautchen might be confused. However, the clear layer can be identified by its tendency to curl and crack during preparation. All other surfaces encountered were relatively featureless, except for impressions left by dermal “papillae” associated with mechanoreceptors. Using a method for examining preserved specimens to determine the stage in the shedding cycle, we assess two sources of variation in epidermal surface structure: stage in the shedding cycle and wear. Examination of immature renewal‐phase epidermis suggests that the oberhautchen does not mature synchronously across a single scale or across body regions. Comparing inner‐ and outer‐generation oberhautchen in sheddingphase epidermis, we conclude that changes in surface appearance caused by natural wear fall into two categories: discrete scratches and accumulation of debris. We see no evidence of overall “buffing” on a microscopic level, though surface structure may be obscured by scratches and gouges. Many squamate taxa show a gradient from low relief surface structure on elevated regions such as keels to high relief patterns at scale edges. This gradient is not due to wear; its significance is unknown.
Muscular mechanisms of snake locomotion: An electromyographic study of lateral undulation of the florida banded water snake (Nerodia fasciata) and the yellow rat snake (Elaphe obsoleta)
Authors: Jayne Bruce C.
Published: February 2005

Electromyography and cinematography were used to determine the activity of epaxial muscles of colubrid snakes during terrestrial and aquatic lateral undulatory locomotion. In both types of lateral undulation, at a given longitudinal position, segments of three muscles (Mm. semispinalis‐spinalis, longissimus dorsi, and iliocostalis) usually show synchronous activity. Muscle activity propagates posteriorly and generally is unilateral. With each muscle, large numbers of adjacent segments (30 to 100) show simultaneous activity. Terrestrial and aquatic undulation differ in two major respects. (1) During terrestrial undulation, muscle activity in a particular region begins when that portion of the body has reached maximal convex flexion and ends when it is maximally concave; this phase relation is uniform along the entire snake. During swimming, however, muscle activity passes posteriorly faster than the wave of vertebral flexion, causing the relation of muscle activity to flexion to change along the length of the snake. (2) In the terrestrial mode, the block of active muscle segments remains approximately constant in size as it passes down the snake, whereas during swimming the number of adjacent active muscle segments increases posteriorly. Despite the fact that Elaphe obsoleta has nearly twice as many body vertebrate as Nerodia fasciata (240 vs. 125), the only difference observed in the swimming of these two species is that a larger number of adjacent muscle segments is simultaneously active in comparable regions of Elaphe obsoleta than in Nerodia fasciata.
Transmission electron microscopic study of the saccule in the embryonic, larval, and adult toadfish Opsanus tau
Authors: Sokolowski Bernd H. A. , Popper Arthur N.
Published: February 2005

The development of the sensory epithelium of the saccular macula of Opsanus tau was studied with transmission electron microscopy. In the 10–12 somite embryo all cells of the newly formed otocyst are morphologically undefined, having an apically placed cilium with an underlying basal body and parabasal body. Junctional complexes are characterized primarily by tight junctions and a few desmosomes. In the 17‐somite embryo the sensory cells begin to differentiate and are definable by the development of microvilli, which lack a cuticular plate. When the embryo has approximately 25–30 somites, ganglion cells differentiate and send their nerve processes toward the thin, disrupted basal lamina and the developing rhombencephalon. Desmosomes are more definable in the sensory regions at this age.

As the myotomes begin forming (approximately 5–8 days before hatching), the nerves invade the sensory epithelium, and the developing sensory cells contain dense bodies surrounded by clear, membrane‐bound vesicles. Clear synapticlike vesicles are also found throughout the infranuclear region of the sensory cells. However, afferent fibers lack a postsynaptic density. Three to 6 days prior to hatching a cuticular plate begins forming under the ciliary bundles and support and peripheral cells begin to morphologically differentiate. Two to 4 days before hatching the cuticular plate is well formed, desmosomes are numerous, afferent synapses and complete, and the sensory cells are in the upper two‐thirds of the epithelium. Seven to 10 days after hatching, sensory cells have efferent synapses and ganglion cells and nerves show a myelin coat. These results suggest that sensory cells begin their development prior to VIIth nerve innervation, although the orientation and pattern development of these cells may be related to the formation of the cuticular plate, desmosomes, afferent innervation, and basal lamina formation.
Morphology and locomotor adaptations of the bovid femur in relation to habitat
Authors: Kappelman John
Published: February 2005

Extant bovids inhabit a wide diversity of environments that range from forest to savanna and display locomotor patterns that are habitat specific. I report here on an investigation of the linkage between these locomotor patterns and habitat based on a study of the morphology of the bovid femur. Femoral head shape, shaft dimensions, and knee structure are examined and support a statistically significant separation of the different morphological complexes present in bovids from forest, broken cover, and savanna habitats. Morphological differences are primarily related to locomotor patterns as reflected in the degree of cursoriality displayed by bovids in different habitats. Cursorial bovids from savanna environments have laterally expanded femoral heads that act to limit the degree of abduction and axial rotation at the hip, and elliptically shaped distal femora that increase the moment arm of the extensor muscles that cross the knee. Forest bovids have spherically shaped femoral heads. This morphology permits a much higher degree of abduction and axial rotation at the hip and appears to provide greater maneuverability in a vegetationally complex habitat. Bovids living in broken cover environments that fall between the extremes of closed canopy forest and savanna display an intermediate set of femoral characters. This approach to the relationship between habitat and locomotion offers a potentially powerful means with which to examine the interplay between structural form and function in bovid evolution.
Anatomy and function of the mouthparts of the biting midge, Culicoides sanguisuga (Diptera: Ceratopogonidae)
Authors: Sutcliffe James F. , Deepan Paul D.
Published: February 2005

The mouthparts and upper food canal of the biting midge, Culicoides sanguisuga, are described with light, scanning electron, and transmission electron microscopy. The stylets (labrum, hypopharynx, mandibles, laciniae) are individually described so that their union into the piercingsucking syntrophium can be understoo. Labial anatomy and relationships to the syntrophium are also described. Syntrophial integrity is based on a complex system in which (1) the mandibles articulate with each other and with the hypopharynx; (2) the edges of the labrum are hooked over the sides of the mandibles; (3) the laciniae “clasp” the hypopharyngeal‐mandibular complex to the labrum; and (4) the labellum holds the stylets together terminally.

We propose that all muscles attached to the mandibles of the biting midge serve as retractors. This, combined with the fact that the mandibles have only one toothed edge (rearward‐directed teeth on the lateral edge), suggests that retraction is the only active cutting stroke during biting. The mechanism contrasts with that of black flies (simuliids), which have mandibular protractors and retractors and teeth on both lateral and medial mandibular margins.
Ear morphology of the frog‐eating bat (Trachops cirrhosus, family: Phyllostomidae): Apparent specializations for low‐freqency hearing
Authors: Bruns Volkmar , Burda Hynek , Ryan Michael J.
Published: February 2005

The frog‐eating bat (Trachops cirrhosus) is unusual among bats studied because of its reliance on low‐frequency (<5 kHz) sounds emitted by frogs for prey localization. We investigated the ear of this bat in order to identify anatomical features that might serve as adaptations for low‐frequency hearing. Trachops cirrhosus has a variety of anatomical features that might enhance low‐frequency hearing, either by increasing sensitivity to low‐frequency sounds or expanding the total frequency range to include lower frequencies. These bats have long pinnae, and a long and wide basilar membrane. The basal portion of the basilar membrane is much stiffer than the apical portion, and the basal portion of the tectorial membrane is more massive than the apical portion. There is also a concentration of mass in the apical portion of the cochlea. T. cirrhosus possesses the largest number of cochlear neurons reported for any mammal, the second highest density of cochlear neurons innervation known among mammals, and three peaks of cochlear neuron density. Other bats have two peaks of cochlear neuron density, lacking the apical concentration, while other mammals usually have only one. T. cirrhosus differs from most other small mammals and bats in characteristics of the apical portion of the cochlea, i.e., that area where the place theory of hearing predicts that low frequencies are detected.
Architecture and consequent physiological properties of the semitendinosus muscle in domestic goats
Authors: Gans Carl , Loeb Gerald E. , de Vree Frits
Published: February 2005

Morphological and physiological analyses confirm that the semitendinosus muscle of goats contains two separate compartments in series, each with distinct innervation. These compartments of the muscle are in turn composed of short fibers (approximately four fibers in series in the proximal compartment and seven to eight fibers in the distal compartment) which overlap each other for more than 30% of their length, with much of the overlapping portions consisting of slender tails that terminate at one‐tenth of the midfiber diameter. Groups of fibers are associated into relatively narrow bands that run end‐to‐end in each compartment. The data suggest that the maximum length of muscle fibers may be limited; even the fibers of parallelfibered muscles may not scale with the dimension of the animal.
Sex differentiation and early gonadal development in Bombina orientalis (anura: Discoglossidae)
Authors: Lopez Kristin
Published: February 2005

Gonadal differentiation in premetamorphic Bombina orientalis is described and staged. The pattern of events during differentiation in Bombina differs in several respects from that previously described in other anurans. The Bombina gonad initially develops on the ventral surface of the vena cava, where there is no pre‐existent somatic genital ridge prior to the arrival of the germ cells. The sexually undifferentiated gonad does not have a distinct cortex and medulla; instead, medullary cells ingress from the mesonephric blastema during sexual differentiation. Formation of a testis or an ovary appears to depend on the ability (or lack of ability) of the medulla to invade the germ cell‐containing cortex. In the germ line, sexual differetiation can be recognized by a premeiotic increase in oogonial cell volume.
Mechanics of drinking in the mallard (Anas platyrhynchos, anatidae)
Authors: Kooloos J. G. M. , Zweers G. A.
Published: February 2005

Water drinking in the mallard is accomplished by a fine‐tuned set of movements of upper and lower jaw and of the tongue. During immersion of the tips of the bill, the oral cavity is formed into smaller volumes containing water and into connecting tubes. Two mechanisms serve the water transport: (1) lingual and jaw movements press water from the water‐containing spaces into the tubes; (2) a quantitative simulation of the shape of the oral cavity during immersion shows that the two tubes are so narrow that capillary action also contributes to water transport.

Thereafter, the tips of the bill are raised until they point upward. In this “tip‐up” position, water flows into the esophagus because of gravity. We conclude that, in addition to normal tip‐up drinking observed in almost all Passeriformes and Galliformes, a second type of tip‐up drinking may be distinguished in Anseriformes. The integration of the drinking mechanism, keeping the water inside the mouth, and the straining mechanism, expelling the water along the beak rims, is effected by specific actions of the elaborate lingual apparatus.
Pituitary gland of the garter snake (Thamnophis): Morphology and immunocytochemistry
Authors: Wurst Gloria Z. , Pearson Anita K. , Licht Paul
Published: February 2005

The three‐dimensional gross morphology of the pituitary gland of the garter snake (Thamnophis sirtalis) is presented. Hormone‐producing cells of the pars distalis were localized immunocytochemically. Corticotropes and lactotropes occur in the anterior two‐thirds of the gland; corticotropes are especially numerous in the area of the pars distalis nearest the median eminence, and lactotropes are most abundant medially. Somatotropes are restricted to the posterior one‐third of the pars distalis. Gonadotropes and thyrotropes are scattered throughout the pars distalis and in favorable sections form a network of cells enclosing clusters of peptide‐secreting cells.
Effect of photoperiod on testicular function in blinded and non‐blinded marbled newts, Triturus marmoratus (caudata, salamandridae)
Authors: Fraile Benito , Paniagua Ricardo , Rodriguez Marina C. , Saez Francisco José
Published: February 2005

Adult male marbled newts (Triturus marmoratus) were collected at the beginning of the spermatogenetic period and exposed to different photoperiods (natural photoperiod with progressively increasing daylengths, total darkness, 8L:16D, 12L:12D, 16L:8D, and continuous light) for 3 months at 20°C. To evaluate the effect of photoperiodic input via pineal gland photoreceptors, two additional groups of newts were blinded by a non‐aggressive method (an elastic rubber cap was adjusted to the head to cover the eyes but not the pineal photoreceptors). These animals were exposed either to the natural photoperiod or to 12 hr of light per day. Quantitative histologic studies on testicular development and germ‐cell volume revealed no significant differences between non‐blinded and blinded animals. Testicular size and germ‐cell development increased in the following order: total darkness, constant light, 8L:12D, natural photoperiod, 12L:12D, and 16L:8D. These results suggest that (1) long photoperiods enhance testicular development, whereas short photoperiods or an environment of continuous light have the opposite effects and (2) the effect of photoperiods on testicular function in newts is independent of the ocular photoreceptors.
Functional morphology of the pharyngeal jaw apparatus in perciform fishes: An experimental analysis of the haemulidae
Authors: Wainwright Peter C.
Published: February 2005

A new mechanical model for function of the pharyngeal jaw apparatus in generalized perciform fishes is developed from work with the family Haemulidae. The model is based on anatomical observations, patterns of muscle activity during feeding (electromyography), and the actions of directly stimulated muscles. The primary working stroke of the pharyngeal apparatus involves simultaneous upper jaw depression and retraction against a stabilized and elevating lower jaw. The working stroke is characterized by overlapping activity in most branchial muscles and is resolved into three phases. Four muscles (obliquus dorsalis 3, levator posterior, levator externus 3/4, and obliquus posterior) that act to depress the upper jaws become active in the first phase. Next, the retractor dorsalis, the only upper jaw retracting muscle, becomes active. Finally, there is activity in several muscles (transversus ventrales, pharyngocleithralis externus, pharyngohyoideus, and protractor pectoralis) that attach to the lower jaws. The combined effect of these muscles is to elevate and stabilize the lower jaws against the depressing and retracting upper jaws.

The model identifies a novel mechanism of upper jaw depression, here proposed to be the primary component of the perciform pharyngeal jaw bite. The key to this mechanism is the joint between the epibranchial and toothed pharyngobranchial of arches 3 and 4. Dorsal rotation of epibranchials 3 and 4 about the insertion of the obliquus posterior depresses the lateral border of pharyngobranchials 3 and 4 (upper jaw). The obliquus dorsalis 3 muscle crosses the epibranchial‐pharyngo‐branchial joint in arches 3 and 4, and several additional muscles effect epibranchial rotation. Five upper jaw muscles cause upper jaw depression upon electrical stimulation: the obliquus dorsalis 3, levator posterior, levator externus 3/4, obliquus posterior, and transversus dorsalis. This result directly contradicts previous interpretations of function for the first three muscles. The presence of strong depression of the upper pharyngeal jaws explains the ability of many generalized perciform fishes to crush hard prey in their pharyngeal apparatus.
Motor innervation and proprioceptors of the mouthparts in the worker honey bee apis mellifera. II. Maxillary and labial nerves
Authors: Masuko Keiichi
Published: February 2005

Sensory and motor innervation of the proboscis by branches of the maxillary and labial nerves of the worker honey bee has been investigated in specimens stained vitally by methylene blue or viewed by scanning electron microscopy. A chordotonal organ consisting of a single scolopidium is present in the maxillary palp. Flexion of the maxillary palp occurs only passively, induced by the flexion of the galea. This chordotonal organ may function as a proprioceptor for the movement of the galea. Another chordotonal organ exists in the prementum of the labium. It contains, on the average, 12 sensory cells and presumably responds to the bending of the labial palp. A nerve‐net of bipolar cells arises from the sensory branches of the maxillary nerve. Free nerve endings derived from the periphery of this nerve‐net expand broadly on the intersegmental membranes connected to the stipes. The right and left nerves to the dilator muscles of the salivarium exchange branches, resulting in the reciprocal innervation of each muscle.
Oviductal morphology and egg shelling in the oviparous lizards Crotaphytus collaris and Eumeces obsoletus
Authors: Guillette Louis J. , Fox Sandra L. , Palmer Brent D.
Published: February 2005

Morphological changes occurring in the oviduct and epithelial cells of the lizards Crotaphytus collaris and Eumeces obsoletus during the natural reproductive cycle were examined and quantified. Additionally, development of the eggshell at different stages of gravidity was described. The anterior uterus of each species has a distinct glandular type which differs between species: in E. obsoletus, the glands are tubular and in C. collaris, branched saccular. The branched saccular glands in the anterior uterus of C. collaris produce collagen‐like material that forms the fibers of the shell membranes. However, fibers from the eggshell of E. obsoletus did not stain for collagen. The shell of both species is composed of a multilayered inner boundary covered externally by fibers of varying thickness. Initial layers are composed of thick fibers all lying along the same general axis. Outer layers of fibers are progressively thinner and an external surface layer composed of glycosaminoglycans (GAGs) is also present. In C. collaris, calcium, which is deposited in relatively small amounts on the shell surface, appears to be secreted by the epithelium of the anterior uterus. The nonciliated secretory epithelial cells covering the villi‐like folds of the posterior infundibulum secrete GAGs. Epithelial cell height of the infundibular villi is greatest during early gravidity. A functional relationship may exist between luteal activity and oviductal secretory activity because the activity of the glandular epithelium varied as gravidity progressed.
Failure to turn eggs during incubation: Development of the area vasculosa and embryonic growth
Authors: Deeming D. C.
Published: February 2005

Effect of turning of the egg during incubation on development of the area vasculosa of the chick embryo was investigated. The size of the area vasculosa was determined by two methods: direct measurement with calipers and measurement of a template cut from the eggshell by use of an automatic surface area recorder. The effects of turning and additionally the effects of lowered temperature (36°C) on both growth of the area vasculosa by day 7 and embryo growth by day 14 of incubation were investigated. The effects of turning during a critical period for turning, from 3 to 7 days of incubation, were also recorded. Generally, failure to turn eggs retarded growth of the area vasculosa. Turning during the critical period stimulated the extent of growth of the area vasculosa by day 7 of incubation and of subsequent embryonic growth by day 14. Incubation at low temperature resulted both in reduced expansion of the area vasculosa and retarded embryonic growth in a pattern similar to that observed for unturned eggs. It is suggested that turning stimulates development of blood vessels in the area vasculosa via localized increases in blood pressure. The effect of a reduced area vasculosa is considered to retard embryonic development through restricted nutrient uptake from the yolk. The prevailing hypothesis that turning prevents deleterious membrane adhesions is questioned in light of these observations. It is suggested that the physiological basis for the need for turning lies in maximizing the growth rate of the area vasculosa to maximize yolk use and embryonic growth rate.
Structural and ultrastructural features of the inlet and outlet regions of the urinary bladders of the leech, Hirudo medicinalis L.
Authors: Wenning Angela , Cahill Mary Anne
Published: February 2005

Each of the 34 nephridia in the leech, Hirudo medicinalis, has its own separate bladder. Urine flows from the last portion of the nephridium, the final canal, into the bladder through a special inlet which prevents backflow of urine. This inlet consists of a vestibule formed by two serially arranged septa, each with a small pore. As no muscles or cilia are associated with either the nephridia or the bladder inlet, urine flow into the bladder is passive. Urine leaves the bladder through an outlet that consists of a urethra with sphincters at both ends and an opening, the nephridiopore, in the ventral skin. The sphincter muscles are distinct from the body wall muscles and receive double innervation: urine retention and release is therefore active.
Scanning microscopy of the developing vagina in postnatal gerbils
Authors: Kress Annetrudi , Spornitz Udo M. , Zobrist Roger
Published: February 2005

Scanning electron microscopy of postnatally developing gerbil vagina (birth to maturity) shows that longitudinal folds form prior to transverse folds; the process of fold formation is initiated on the dorsal wall and proceeds ventrally. From days 1 to 7 postnatally, the vaginal epithelium is composed of either flat or bulging cells, depending on the vaginal region. The luminal cell surface is covered with uniform stubby microvilli and solitary cilia. Between days 9 and 20, the flat cells with distinct cell boundaries spread toward more proximal areas, leading to the formation of mixed patches of cells with flat or rounded apices. Individual elongated microvilli or tufts of forked microvilli may sprout from their surfaces. Solitary cilia gradually disappear.

The transition from immature to mature vaginal epithelium starts around day 20, when individual cells recess below the level of neighboring cells. This process spreads throughout the vagina during the following days, reflecting local changes in the subsurface layers of the epithelium preparatory to exfoliation. Around day 40 the actual exfoliation of the luminal cell layer starts. By this time the surface characteristics of many of the desquamating cells have changed. In addition to microvilli, microridges are being formed. The process of exfoliation is finished by about day 60. The newly appearing cell layers now transform into typical cornified cells of the cycling vaginal epithelium.
Form and function of the feeding apparatus of Alligator mississippiensis
Authors: Busbey Arthur B.
Published: February 2005

The architecture of the jaw muscles and their tendons of Alligator mississippiensis is described and their function examined by electromyography. Alligator grabs its prey with forward lunges or rapid lateral movements of the head. It does not engage in regular masticatory cycles. Prey is manipulated by inertial movements and the tongue does not appear to play any role in transport. The Mm. adductor mandibulae externus, adductor mandibulae posterior, and pterygoideus activate bilaterally and simultaneously during rapid closing or crushing. The M. pterygoideus does not act during prey holding whereas the Mm. adductor mandibulae externus, adductor mandibulae posterior continue to be active. The Mm. depressor mandibulae and intramandibularis are variably active during both jaw opening and closing.
Post‐hatching growth of the kidney in the chukar (Aves: Phasianidae)
Authors: Goldstein David L.
Published: February 2005

The post‐hatching growth of the kidney of the chukar partridge, Alectoris chukar, was studied in birds aged 5, 24, 56, and 140 days. As body mass increased from 24 gm (5 d) to 479 gm (140 d), kidney mass increased from 0.16 to 1.6 gm. The number of nephrons in the kidney increased through age 56 d, but did not change thereafter. This increase was primarily a function of increasing development of the cortical regions; more than 90% of reptilian‐type nephrons developed after hatching. The full complement of medullary cones was present at hatching. However, the lengths of the medullary cones and the number of loops of Henle of mammalian‐type nephrons contained in each medullary cone increased through growth, so that approximately 65% of the mammalian‐type nephrons developed after hatching. The chukar kidney contained 19% mammalian‐type nephrons at age 5 d, but this was reduced to approximately 5% by 24 d, after which the proportions of mammalian‐and reptilian‐type nephrons did not change. This study demonstrates that metanephric kidney growth in birds begins in the deepest regions of the kidney and then extends peripherally but also that mammalian‐type nephrons continue to develop throughout kidney growth, presumably from pre‐existing reptilian‐type nephrons.
Ultrastructural features of the developing eosinophils in bone marrow and spleen of the musk shrew, Suncus murinus
Authors: Ishizeki Kiyoto , Nawa Tokio
Published: February 2005

Eosinophilopoiesis in the musk shrew, Suncus murinus, a representative of the order Insectivora, was studied by light and electron microscopy. To examine biochemical features of cytoplasmic granules, extraction with proteolytic enzymes was carried out on ultrathin sections of bone marrow. In this species, eosinophils are produced in the same manner in both spleen and bone marrow. Developing eosinophils were distinguished as belonging to four stages, recognized by ultrastructural changes in cytoplasmic organelles as well as the eosinophilic granules during maturation. Granulogenesis began by budding of vacuoles containing flocculent material from the concave face of the Golgi apparatus, in the promyelocyte to myelocyte stage. The matrix of developing granules transformed into a finely granular structure, and the large spherical granules of mature eosinophils were homogeneous without crystalline cores. It was shown by proteolytic enzyme extraction that the proteinaceous cores of mature granules were uniformly removed; there was no evidence that they contained crystalloid inclusions. These results indicate that shrew eosinophils can be regarded as cells that retain a prototype of eosinophil granules, probably like those of ancestral mammals rather than those of higher living Mammalia.
Porosity of eggshells from wild and captive, pen‐reared alligators (Alligator mississippiensis)
Authors: Wink Carole S. , Elsey Ruth M. , Bouvier Marianne
Published: February 2005

Artificially incubated fertile eggs from wild alligators have a significantly better hatch rate than those of captive, pen‐reared alligators, possibly due to differences in the morphology of the eggshells. We compared the morphology of eggshells of wild alligators to those of captive alligators living in semi‐natural environmental pens. Lengths and widths of eggs were measured and volume was determined, assuming an ellipsoid shape. Eggs were also evaluated for the quality of the eggshell (the presence or absence of rough deposits). Pieces of shell were cut from unincubated eggs and from eggs incubated for 55 days (just before hatching) and examined by scanning electron microscopy. Open pores on the outer surface of the shells were counted and thickness of the pieces was measured from micrographs. Results indicated that the number of pores on eggshells was lowest in eggs of captive alligators with early embryonic death. The number of pores was intermediate in eggs with early embryonic death from wild alligators, and the number of pores was highest in eggs with full‐term embryos from wild or captive alligators. It is suggested that decreased porosity of eggshells may be associated with early embryonic death, is more prevalent in captive animals, and may, therefore, be related to poor hatch rate among penreared alligators.
Histology and histochemistry of the oviductal sperm storage pockets of the agamid lizard Calotes versicolor
Authors: Kumari T. Ruth Shantha , Sarkar H. B. Devaraj , Shivanandappa T.
Published: February 2005

Some reptiles are known to possess sperm storage in the female genital tract. Examination of the oviduct of the lizard Calotes versicolor shows the presence of sperm in storage pockets of the uterovaginal region throughout the reproductive cycle. Histochemical studies indicate that the epithelium of these pockets resembles the local oviductal epithelium and that a considerable amount of activity of steroidogenic and metabolic enzymes exists.