bluuebunny/crossref_metadata_2025_split huggingface dataset:
The segmental origin of the appendages of the head and anterior body segments of a spiroboloid milliped, Narceus annularis
Authors: Bodine Martha Weiss 
Published: February 2005

AbstractStudy of a series of embryos showed that the spiroboloid leg arrangement (1 pair of legs on each of the first 5 segments) is derived from the typical leg arrangement (no legs on segment 1, 1 pair on segments 2 through 4, and 2 pairs on segment 5) by a shifting forward one segment of the first four pairs of legs.A careful re‐examination of the literature, especially papers by Robinson ('07), Silvestri ('03, '49), Pflugfelder ('32), and Manton ('61), combined with observations of Narceus embryos led to the conclusion that (1) the anterior body segments are primatively single (2) the gnathochilarium is composed of only one pair of mouthparts, the diplopod head having but two gnathal segments, and (3) the intercalary segment is present in the Diplopoda.
Studies on the fine structure of spermatids and spermatozoa of the crab, Pinnixia sp.
Authors: Reger James F. 
Published: February 2005

AbstractEarly spermatids of the carb, Pinnixia sp., are characterized by a large nuclear/cytoplasmic ratio. During early spermiogenesis an organelle, composed of pentalaminar membranes derived from the endoplasmic reticulum and nuclear membranes, is formed. Portions of this organelle become incorporated within a cylinder‐shaped invagination of the acrosome. Portions of the nuclear membrane disappear beneath the acrosome resulting in intermingling of nucleoplasm, centrioles and mitochondria. The nuclear membrane elsewhere is found as a pentalaminar membrane underlying the plasma membrane. Centrioles are found in mature spermatozoa at the base of the cylinder‐shaped acrosomal invagination, and mitochondria are found intermingled with nuclear remanants surrounding the acrosome. This datum is compared to previously described events in spermiogenesis of other decapod crustacea and arthropods exhibiting similar modes of spermiogenesis. It is concluded that the differences and/or similarities exhibited by centrioles and mitochondria in these forms could be significant in terms of subsequent zygote differentiation.
Chick lens differentiation in vitro
Authors: Katoh Arthur , Breverman Max 
Published: February 2005

AbstractIf that portion of a chick embryo destined to form the eye, the lens, part of the brain and the surrounding head region be removed from the chick before the lens has begun to develop, and placed in a liquid culture medium for four days, a structure resembling the lens will form in appropriate proximity to the presumptive retina, and the cells of the lens will synthesize proteins unique to and characteristic of the lens. The time course of morphological development of such explants is here described.In vitro the lens placode dose not invaginate to form a lens vesicle, as it does in ovo. Instead placode cells elongate directly to form fibre cells. The shape of the lens formed in this aberrant manner is remarkably similar to that of normal lens.At least one, and probably all three, of the characteristic crystallins of the lens form in these aberrant lenses, the cytological and biochemical differentiation of which proceeds normally, despite failure of the normal morphogenetic activities of the organ.
The lizard ear: Scincidae
Authors: Wever Ernest Glen 
Published: February 2005

AbstractObservations on inner ear structure were made in five species of Scincidae, together with measurements of auditory sensitivity in terms of cochlear potentials. The basilar membrane and auditory papilla show a characteristic form, with considerable uniformity in dimensions except for a moderate expansion in the dorsal region and a more prominent one at the ventral end.A characteristic feature is the presence of a tectorial membrane that covers a large part of the surface of the medial limbus, but never leaves this surface and thus fails to make any contact with the auditory papilla. Hair‐cell stimulation is achieved entirely through operation of the inertia principle (or equivalent principles) by means of a chain of sallets extending along most of the cochlea but giving way in the region of the ventral expansion to a single large body, the culmen papillae.The sensitivity varies in the five skinks studied from better than average to some‐what below average in comparison with other lizard species. Thus an inertial (or inertia‐like) system of hair‐cell stimulation compares favorably with the tectorial membrane (restraint) system exhibited in the ears of most other lizards and all the higher animals.
Chemosensitive hairs in spiders
Authors: Foelix Rainer F. 
Published: February 2005

AbstractSpiders possess curved, blunt‐tipped hairs on all legs and palps, which differ in many details from the straight, sharp‐pointed, tactile hairs: (1) the blunt tip is open to the outside, which can be demonstrated by high resolution microscopy and by the penetration of dyes; (2) the hair shaft has a double lumen which consists of a circular (tube) and a crescent shaped lumen; (3) this hair is innervated by two to three bipolar neurons whose dendrites enter the small tube, where they arborize into 16–20 branches. Multiple innervation and an open tip give strong evidence for a chemoreceptive function. Concluding from their position and distribution on the distal leg parts, a contact chemoreception is tentatively proposed. This interpretation is supported by the close structural analogy to the known contact chemoreceptors in insects. Observation of behavior indicates the importance of a contact chemoreceptor on spider legs. Other possible chemoreceptors in spiders which have been described previously by other authors are discussed.
The fine structure of coelomocytes in the annelid Enchytraeus fragmentosus
Authors: Hess Roberta T. 
Published: February 2005

AbstractTwo types of coelomocytes, the mucocyte and the phagocyte, occur in Enchytraeus fragmentosus. Other free cells observed within the coelomic cavity include chloragogen cells, peritoneal cells and some anucleate granular cells. Three forms of mucocytes occur and are believed to represent developmental stages. The first stage is one in which the mucous droplets are forming in the Golgi region. The second stage is a mature form, and the third stage is one in which the mucous droplets are being released. The phagocytes generally are quite large, and inclusions vary from recognizable portions of chloragogen cells to extremely small, electron‐dense cytosomes. The origin of the coelomocytes could not be determined. Probable functions of coelomocytes are discussed.
Survival of xenogeneic grafts of embryonic pigment and carapace rudiments in embryos of Chelydra serpentina
Authors: Yntema C. L. 
Published: February 2005

AbstractIn a study of survival of embryonic grafts in turtles, Chelydra was used as host and Chrysemys and Amyda as donors. Somites and overlying ectoderm with or without adjacent neural tube were transplanted. The operations were unilateral and orthotopic. The involved the anterior portion of the carapace. In other experiments, bilateral neural crest and dorsal neural tube were transplanted orthotopically.In experiments with Chrysemys as donor, pigment cells formed conspicuous red areas ventrally when neural crest was included in the graft. This pigment faded gradually but persisted for three or four years.When somites and adjacent ectoderm of Chrysemys carapace were transplanted, the graft area was lightly pigmented at hatching. This pigmentation increased subsequently. The Chrysemys grafts were either accepted or partially rejected. In cases of apparent complete acceptance, the graft region took on characteristics of the host.When Amyda served as donor of carapace rudiments, the graft area retained characteristics of the donor. At hatching, dark spots on a yellow background were present and scutes were absent. A few months after hatching, the graft area became necrotic. Subsequently, scutes with host characteristics or skin covered the graft area.
Tooth development in Latimeria chalumnae (Smith)
Authors: Grady John E. 
Published: February 2005

AbstractTooth development in Latimeria was studied with the use of light microscopy, polarized light microscopy and microradiography.Teeth develop from cells derived directly from the basal layer of the oral epithelium in areas where teeth have been shed or are being resorbed. The teeth are composed of true enamel, orthodentine and pulp tissues. Attachment is accom‐plished by bony attachment ankylosing the teeth to the basal bone of dental plates. The histologic picture of Latimeria teeth resembles more closely the teeth of tetrapods than those of most bony fish.
A cytologic analysis of the bag cell control of egg laying in Aplysia
Authors: Coggeshall Richard E. 
Published: February 2005

AbstractA fine structural analysis of the ovotestis in Aplysia was undertaken in order to analyze the site of action of the bag cell hormone. Five stages of oocyte development are described. Of particular interest is the fact that the yolk seems to be synthesized primarily by the granular endoplasmic reticulum. In addition, small muscle cells whose long, thin processes surround the follicle of the ovotestis have been pointed out. This paper suggests that bag cell extract has a direct action on these small muscle cells causing them to contract and thus expel oocytes from the ovotestis. The evidence for this suggestion is that (1) these muscle cells are the most obvious effector cells in the ovotestis, (2) there are no signs of neural innervation of these muscles, (3) the time course for the liberation of the oocytes is so short that any other method of oocyte release is unlikely, (4) there is no cytologic evidence for any other expulsion process except muscular contraction, and (5) the ripe oocytes are attached to other cells of the wall of the ovotestis only by very small, simple junctions, thus making them the most likely cells to be expelled by muscular contraction.
The venous system of the head and neck of the opossum (Didelphis virginiana)
Authors: Dom Richard , Fisher Barry L. , Martin George F. 
Published: February 2005

AbstractThe venous system of the head and neck of the opossum, Didelphis virginiana, was studied by injecting the veins with a tinctorial mass. Gross dissection spechmens injected with a colored gelatin solution and corrosion specimens prepared by Batson's technique (Batson, '55) were utilized to describe the venous pattern in greater detail than is presently available in the literature. The venous drainage of the superficial structures of the head is principally by way of the V. jugularis externa and its tributaries. Although small emissary veins connect the Sinus cavernosus with the Plexus pterygoideus and the V. maxillaris, the dural venous sinuses drain primarily into the Plexus vertebralis internus and into the V. maxillaris by way of the V. emissaria foraminis retroarticularis. The small V. jugularis interna receives minor connections from the Plexus pterygoideus, the Sinus cavernosus and the Sinus petrosus ventralis as well as anastomotic tributaries from the Plexus vertebralis and the plexus of veins around the hyoid bone. However, the V. jugularis interna serves mainly as a pathway for venous drainage from the deeper structures of the neck and only minimally for draining the brain.
The endodermal nerve net of Scyphozoa
Authors: Passano Kari N. , Passano L. M. 
Published: February 2005

AbstractThe endodermal nerve nets of the scyphozoan jellyfish Phacellophora camtschatica and Cyanea capillata were stained with methylene blue. Small animals (3–7.5 cm in diameter) stained easily. The endodermal nerve net of both species is a synaptic net consisting of bipolar and some few tripolar nerve cells with unbranched neurites. The neurites terminate on other neurites. Very few free nerve endings were observed. The neurites have a diameter of 1/4‐1/2 μ and there is no indication of the presence of neurites too fine to be followed in the light microscope.The gross appearance of the net changes with the size of the medusa. Staining 15–53 cm diameter animals showed that the nerve cells increase in size with the size of the animals, that the density of the nerve net decreases.The endodermal nerve net is very similar to our interpretation of the Diffuse Nerve Net of the ectoderm but without the typical primary sense cells. In both cases the appearance of branching neurites is interpreted as an artifact caused by neurites terminating on other neurites.
Reproduction and the mechanism of meiotic restitution in the parthenogenetic lizard Cnemidophorus uniparens
Authors: Cuellar Orlando 
Published: February 2005

AbstractGross details of the reproductive cycle and the cytology of oogenesis were studied in 155 egg clutches produced by 69 captive individuals of the triploid parthenogenetic lizard Cnemidophorus uniparens. The mean clutch cycle lasted 23 days. The mean number of ova per clutch was 3.3, and the mean number of oocytes per right and left ovaries was 1.65 and 1.70, respectively. Comparison of the size of the oocytes at ovulation (9–10 mm) with the estimated mean duration of vitellogenesis (8.8 days) gave an average of approximately 1 mm yolk deposition per day. The mean time for the retention of eggs in the oviducts was 9.3 days. The germinal disc of the oocyte consists of a series of layers formed by the arrangement of various cytoplasmic and yolk particles in the polar region. In a mature oocyte the germinal vesicle is located immediately below the vitelline membrane and lies at the center of the germinal disc. The germinal vesicle is characterized by a dense disc‐like cluster of diplotene chromosomes. Diplonema extends until near ovulation when the oocytes have attained a size of about 9 mm. Diakinesis and metaphase I occur rapidly and immediately prior to ovulation. Counts of approximately as many bivalents as there are somatic chromosomes were obtained from oocytes at diakinesis and metaphase I.The second division occurs almost immediately before or at the precise moment of ovulation. The chromosomes of the first polar body consist of dyads, of which there are as many as the triploid number of 69. A metaphase II plate obtained in polar view also revealed dyad chromosomes, of which there were approximately as many as the triploid somatic number. The second telophase is normal as evidenced by formation of the second polar body. Chromosomes from the opposing telophase plates show a monad structure. The presence of as many bivalents in the first division as the triploid somatic number of 69 indicates that the 3N condition of C. uniparens was doubled prior to meiosis. This is further supported by the occurrence of two maturation divisions each giving rise to a polar body, by the dyad structure of the chromosomes in the first polar body and the second metaphase, and by the presence of monochromosomes at telophase II. Thus, parthenogenesis in these lizards is of the meiotic type. The somatic number of chromosomes is doubled early in oogenesis presumably by a premeiotic endoduplication, and the 3N level is restored by two subsequent maturation divisions.
Circumfila and other sense organs on the antenna of the sorghum midge (Diptera, Cecidomyiidae)
Authors: Slifer Eleanor H. , Sekhon Sant S. 
Published: February 2005

AbstractThe antennal flagellum of the male sorghum midge is about a millimeter long and may bear over 500 sense organs. These consist of (1) tactile hairs, (2) thin‐walled pegs, (3) circumfila and (4) very small pegs of unknown function. Each of the 12 subsegments of the flagellum is divided into two globular nodes and each of these is encircled by a circumfilum of from 6 to 14 loops. The circumfila are attached to the antennal surface by short stalks. The loops of the circumfila have the basic structure of thin‐walled chemoreceptors: (1) very small pores in their delicate wall and (2) a lumen filled with branches of dendrites from sensory neurons. The outer surface of the circumfilum is covered with a labyrinth of fine ridges between which the pores are located. Some evidence was obtained that the circumfila are produced in the pupa by bifurcate trichogen cells.The flagellum of the female is shorter than that of the male and composed of 12 cylindrical subsegments. The circumfila of the female lie close to the surface to which they are attached by short stalks. Each is composed of two parts that encircle the subsegment and of two others that run lengthwise between the circles. The surface is nearly smooth, perforated by fine openings and lacks the complex pattern of ridges seen in the male. It also has more dendrite branches but, otherwise, has the same basic structure.
The migration of blood cells of the bone marrow through the sinusoidal wall
Authors: De Bruyn Peter P. H. , Michelson Sonia , Thomas Thurlo B. 
Published: February 2005

AbstractElectron microscopic observations on the mechanically undisturbed guinea pig bone marrow show that the sinusoidal lining is continuous. There are neither intercellular nor intracellular apertures allowing free communication between the extravascular and intravascular compartments. A transient migration pore is only formed during the diapedetic transit of blood cells. Serial sections show that this aperture is transcellular. A functional continuity of the sinusoidal lining appears to be maintained during the diapedesis of blood cells, which is evident from the absence of a significant extravascular leakage of plasma during this process.
Fine structural studies of Johnston's organ in the tobacco hornworm moth, Manduca sexta (Johannson)
Authors: Vande Berg Jerry S. 
Published: February 2005

AbstractThere are approximately 650 scolopidial units in Johnston's organ of the tobacco hornworm moth, Manduca sexta. These sensory units exhibit greater complexity than noted previously (Gray, '60; Howse, '65; Uga and Kuwabara, '65; Moeck, '68; Ong, '69; Schmidt, '69).Each scolopale is innervated by a bipolar neuron whose dendrite terminals are modified into three ciliary structures. The largest of these differentiates near the tip into a multitubular structure. The remaining two cilia are structurally similar along the entire length of the scolopale shaft. From each of their bases, a collagen‐like structure differentiates into numerous microtubules which extend proximally into individual channels of dendritic cytoplasm. A third channel, with a less developed root apparatus, was apparent for the largest cilium.Preliminary evidence suggests a proprioceptive function for this structure rather than an auditory one.
Growth of the calcareous skeleton during regeneration of spines of the sea urchin, strongylocentrotus purpuratus (stimpson): A light and scanning electron microscopic study
Authors: Heatfield Barry M. 
Published: February 2005

AbstractGrowth of the skeleton of regenerating spines of the sea urchin, Strongylocentrotus purpuratus, was studied with the light and scanning electron microscopes during the formation of a growth ring or cycle.Growth was initiated about three days after fracture and was linear between 5 and about 40 days after fracture, with a mean rate of 0.16 mm/day. There‐after, a decline in growth rate was observed, being attributed to abrasion.The new skeleton first appeared as minute, conical „micro‐spines”︁ on the fractured surface of the spine shaft initiating regeneration of the inner zone of meshwork. Subsequent growth of micro‐spines of both the developing inner zone of meshwork, and an outer zone of radiating wedges, formed a conical fenestrated skeleton on the fractured surface of the shaft. Further deposition of micro‐spines along the shaft, initially at the level of fracture, formed meshwork which gradually became solidified externally resulting in a new cycle about 60 days after fracture. In contrast, a new cycle was initiated at the milled ring in non‐fractured spines during total regeneration on bare tubercles, demonstrating that growth of spines also takes place in the absence of fracture.Experiments conducted in vitro demonstrate that spine regeneration is not a polar phenomenon.
The pharyngeal bone musculature of the carp, Cyprinus carpio
Authors: Eastman Joseph T. 
Published: February 2005

AbstractThe carp, Cyprinus carpio, was found to have eight pairs of muscles inserting on the pharyngeal bones. These were the levator arcus branchialis V, retractor os pharyngeus superioris, retractor os pharyngeus inferioris, cleithropharyngeus superficialis, cleithropharyngeus profundus, coracobranchialis posterior, transversus ventralis V and subarcualis rectus communis. Complete morphological descriptions of the muscles are given along with relevant osteological information. The pharyngeal muscles function in mastication by moving the bones and their attached teeth against the chewing pad so that crushing and grinding of food occurs during occlusion. In addition, certain pharyngeal bone muscles enlarge the lumen of the posterior pharynx thereby admitting food to the region of the teeth and chewing pad. The homologies of some of these muscles are considered along with the historical details pertinent to the establishment of a suitable nomenclature for the pharyngeal bone muscles.
Spermatogenesis in Bombyx mori. II. The ultrastructure of synapsed bivalents
Authors: King Robert C. , Akai Hiromu 
Published: February 2005

AbstractIn Bombyx mori the male is the homogametic sex, crossing over occurs only in males, and chiasmata are observed in spermatocytes, but not in oocyte nuclei. If the assembly of synaptonemal complexes is an essential prerequisite for genetic crossing over and chiasmata formation, then the nuclei of Bombyx spermatocytes should contain synaptonemal complexes. Synaptonemal complexes were found in spermatocytes from young four instar larvae. The structure of meiotic bivalents is described using micrographs taken with 100 and 1000 KV electron microscopes. These data together with that from the literature are used to construct a three‐dimensional model of the synaptonemal complex and to suggest its method of origin and its function during crossing over.
The structure and development of the hairpencil glands in males of the queen butterfly, Danaus gilippus berenice
Authors: Pliske Thomas E. , Salpeter Miriam M. 
Published: February 2005

AbstractQueen butterflies do not mate until the male has brushed the tufts of his scented, abdominal ”︁hairpencils„ over the female's head and antennae. The trichogen cells located at the base of each hairpencil are secretory. Presumably, these cells produce the sex pheromone necessary for mating. The liquid secretion must move from a central, microvillus‐lined vesicle through the cuticle of the hairs to coat numerous, free, cuticular „dust”︁ particles which adhere to the hairs' surface. The dust carries the secretion to or near the female's antennae. In the pupal stage the dust particles develop as outpocketings of the hair epicuticle. An amorphous matrix, probably protein epicuticle, is deposited in the outpocketings between the cuticulin layer and plasma membrane of the hair. Before the butterfly emerges from the pupa the matrix becomes enclosed by cuticulin, and the particles pinch off from the hair.