bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the gill ciliation of the American oyster Crassostrea virginica (Gmelin)
Authors: Ribelin Ben W. , Collier Albert
Published: February 2005

Latero‐frontal, para‐latero‐frontal, and frontal ciliary tracts on the gill filaments of Crassostrea virginica (Gmelin) were studied with light microscopy and scanning electron microscopy. Latero‐frontal cirri are complex structures composed of varying numbers of paired cilia. The multiple pairs of cilia which constitute a single cirrus are closely appressed for a portion of their length; they then branch laterally from the central axis in a plume‐like fashion. Latero‐frontal cirri of adjacent gill filaments create a filtration sieve which should be capable of retaining particles smaller than 1 μm in diameter. Para‐latero‐frontal cilia are short, closely spaced cilia arranged as a staggered row along the frontal side of each tract of latero‐frontal cirri. Latero‐frontal cirri and para‐latero‐frontal cilia occur on ordinary, principal, and transitional gill filaments. Frontal ciliary tracts of ordinary filaments are divided into a central, ventrally directed coarse tract, flanked on either side by a dorsally directed fine ciliary tract. The coarse tract is covered by cirri which are comprised of five to eight cilia, while the fine frontal tracts are made up of individually functioning cilia. The frontal ciliary tracts of principal and transitional filaments bear only dorsally directed fine cilia. The unique direction of effective beat of the coarse frontal cirri of ordinary filaments, in combination with the action of fine frontal cilia and the strategic location of mucus producing cells, is used to describe a possible mechanism for the sorting of filtered particles.
Spermatozoa of Ciona intestinalis and analysis of ascidian fertilization
Authors: Woollacott Robert M.
Published: February 2005

The complex array of vestments which surrounds the ascidian oocyte indicates that spermatozoa of these urochordates may be highly modified to effect penetration through the egg‐envelopes and to achieve successful fusion with the female gamete. Examination of the spermatozoa of Ciona intestinalis reveals, however, that they lack an acrosomal vesicle and do not possess detectable amounts of actin. Furthermore, the spermatozoa do not undergo observable morphological alterations when exposed to ammoniated seawater, a treatment known to produce aggregation and an acrosome reaction in other organisms. Ciona spermatozoa do contain significant quantities of proteases. It is hypothesized that the localization of these enzymes may be related to the ridge‐like surface ornamentation which is observed as a component of the head region of Ciona spermatozoa.
Auditory systems of heteromyidae: Cochlear diversity
Authors: Webster Douglas B. , Webster Molly
Published: February 2005

Cochleae (125) from 26 species of the rodent family Heteromyidae (genera Dipodomys. Microdipodops, Perognathus, and Liomys) were compared. In Perognathus and Liomys the scala tympani in the apical portion is extremely narrow with a correspondingly minute helicotrema. In Liomys there is no bone separating scala tympani from spiral ganglion in the upper second and entire third turn. In all species studied the zona pectinata of the basilar membrane is enlarged, with a hyaline mass between upper and lower basilar membrane fibers. This zona pectinata hypertrophy is least at the base of the cochlea and greatest in the upper second turn, decreasing again toward the apex. Basilar membrane width increases rapidly in the first turn and then changes only slightly.

Except for Liomys, all the heteromyids studied have hypertrophied Hensen's cells with long apical processes supporting and forming an elevated reticular lamina. These Hensen's cells reach their maximum size in the upper second and lower third turns; throughout they rest on inner Claudius' cells rather than the basilar membrane. Relative to naso‐occipital length the cochlear specializations are greatest in Microdipodops and least in Liomys just as is the case for middle ear modifications.

The morphological data are consistent with the concept that standing wave phenomena may be important in heteromyid cochlear biomechanics. Single unit data of other workers are also consistent with this interpretation. Like middle ear morphology, inner ear morphology appears adapted to low‐frequency sensitivity–especially in Dipodomys and Microdipodops.
Embryogenesis of Xyleborus ferrugineus (Fabr.) (Coleoptera, Scolytidae). II. Developmental rates of male and female embryos
Authors: Beeman Sylvia L. , Norris Dale M.
Published: February 2005

The developmental rates of male and female embryos of Xyleborus ferrugineus were compared by charting for each sex the mean age for each of ten discrete morphological stages of embryogenesis from pole cell exclusion to eclosion. Male and female embryos developed synchronously from stage 1 (which begins with pole cell exclusion) through stage 4 (which ends with the completion of germ band extension and metamerization). After stage 4 and throughout the remainder of embryogenesis, the mean ages per morphological stage of male embryos were significantly greater than those for female embryos. The expected physiological consequences of a haploid genome in the male embryo as compared to a diploid condition in the female embryo are discussed as the possible basis for the persistent lag observed in male developmental rate after stage 4.
Intrinsic organization of snake medial cortex: An electron microscopic and golgi study
Authors: Ulinski Philip S.
Published: February 2005

The intrinsic organization of medial cortex in snakes, primarily of the genera Natrix and Boa, was studied using Golgi and electron microscopic techniques. The area has three distinct layers, each containing a characteristic population of neurons. Stellate cells comprise a relatively small population of neurons with their somata and dendrites restricted to layer 1, the most superficial layer. Their axons course horizontally in layer 1. Candelabra cells form the largest population of neurons in medial cortex. Their somata lie densely packed in layer 2 and are joined by specialized junctions. Ascending dendrites extend from the somata into layer 1. They consist of spine‐free proximal segments and spine bearing distal segments. Descending dendrites extend from the somata into the upper half of layer 3. The proximal segments bear few spines but branch into several tapered, distal segments which have a moderate covering of spines. One or two axons originate from the descending dendrites and descend through layer 3. The axons bear collaterals in the deep half of layer 3 and eventually bifurcate in the alveus. The medial branches run into the septum; the lateral branches course through other cortical areas. The axons bear frequent varicosities within medial cortex. Periventricular cells lie in the deep half of layer 3, either singly or in clusters. Their ascending dendrites extend radially into layer 1 where they branch into distal segments which resemble those of the candelabra cells. Their descending dendrites arborize horizontally in the alveus and bear a moderate covering of spines. Ependymal cells line the ventricular surface and send radial processes through the area's depth bearing lamellate processes.
Structure and carbohydrate histochemistry of the esophagus in ten teleostean species
Authors: Reifel Conrad W. , Travill Anthony A.
Published: February 2005

The histology and carbohydrate histochemistry of ten teleostean esophagi were compared. Structurally, the four layers of a typical vertebrate digestive tract were consistently present. The epithelium was always stratified and in all but one species (Ictalurus nebulosus) contained taste buds. Esophageal mucous cells were not the typical goblet cells seen in other vertebrates but appeared to be of six different types, pairs of which were associated with particular families. In esocids, poorly developed mucous acini and serous monogranular cells were present. In all species, the subepithelial connective tissue was not divided into definitive lamina propriae and submucosae due to the absence of muscularis mucosae. Variably present in this connective tissue region were argentophilic fibers and in esocids only, randomly dispersed striated muscle fibers. The arrangement of the muscularis was reverse to that of the general vertebrate plan. In mucous cells, three general types of epithelial mucosubstances were identified and in broad terms were recognized as sulfomucins, sialomucins and neutral mucosubstances. Morphological differences were accompanied by differences in carbohydrate localization, each esophageal epithelium containing at least two different mucosubstances. However, the mucosubstances identified in each mucous cell had a profile of characteristics different in some respects from any other. Thus teleostean esophagi appear to perform an integrated diversity of functions as reflected by their complex morphology and carbohydrate histochemistry.
Oogenesis in the Female Sterile (1)42 Mutant of Drosophila melanogaster
Authors: Rizzo William B. , King Robert C.
Published: February 2005

The sex‐linked mutation fs(1)42 was induced by ethyl methane sulfonate. It has no effect on either the external morphology or longevity of adult hemizygotes or homozygotes. Heterozygotes and hemizygotes are fertile, but homozygotes are sterile. Egg chamber development proceeds through stage 8, and thereafter chambers degenerate. Dying follicle cells are seen in chambers at all positions in the ovarioles. Profollicle cells also die within germaria, and clusters of sister cystocytes take longer than normal to receive their coverings of follicle cells. Egg chambers in the vitellarium contain only about 60% the normal number of follicle cells, these generally have greater lateral dimensions, and their nuclei and nucleoli are also larger than normal. The follicular envelope of mutant chambers often contains gaps through which cystocytes send cytoplasmic projections. Abnormalities seen in development of the fs(1)42 oocyte are likely to be due to its envelope of defective follicle cells.
Presence of marchi‐positive myelinoid bodies in the spinal cord white matter of some vertebrate species
Authors: Hildebrand Claes
Published: February 2005

The occurrence of Marchi‐positive myelinoid bodies in the ventrolateral cervical spinal cord white matter was investigated by light and electron microscopy in adult animals of the following species: cat, rabbit, guinea pig, rat, mouse, frog and perch. In addition some observations were made on human specimens. The bodies were found to be present in all the examined species, being most numerous in the rabbit and guinea pig. The lowest incidence was seen in the mouse and frog. The bodies consistently prevailed along the paranodes of large myelinated fibers and generally showed a rounded or ovoid shape. In all animals the size spectrum of the Marchi‐positive myelinoid bodies showed a peak at about 3 μ. The sizes varied from less than 1 μ to over 25 μ. The size range was widest in the perch, the ventrolateral white matter of which contained a great number of very large bodies, and most narrow in the rat. Calculations of the total myelinoid body volume per unit volume of ventrolateral white matter or myelin, showed very high values in the perch (0.03 μ3/μ3 myelin), high values in the cat, rabbit and guinea pig (0.006‐0.007 μ3/μ3 myelin) and low values in the rat, mouse and frog (0.001‐0.002 μ3/μ3 myelin). The white matter specimens from animals with a high total myelinoid body volume contained large fibers with thick myelin sheaths, which were not found in the specimens from animals with a low total myelinoid body volume.

Electron‐microscopically, the picture was rather uniform. In all species examined the myelinoid bodies were composed of a lamellated shell of varying thickness that surrounded a central zone of highly electron‐dense material or an empty cavity. In most cases the bodies were linked to myelin sheaths through oligodendroglial cytoplasm. Less frequently free bodies were observed within astrocytes or microglia.

The findings are interpreted in support of the view that myelinoid bodies may be regarded as an expression of the turnover of myelin material in thick myelin sheaths.
Cytoplasmic bridges within the follicular epithelium of the ovarioles of two diptera, Aedes Aegypti and Stomoxys Calcitrans
Authors: Meola S. M. , Mollenhauer H. H. , Thompson J. M.
Published: February 2005

The cells of the follicular epithelium of the ovarioles of the mosquito, Aedes aegypti (L.), and of the stable fly, Stomoxys calcitrans (L.), have been found to be interconnected by cytoplasmic bridges. Cytoplasmic bridges have been reported between sibling gamete cells of both male and female insects, but these bridges have not been previously reported to exist between somatic cells of insects.
An unusual cytoplasmic organelle in oocytes of Ilyanassa obsoleta
Authors: McCann‐Collier Marjorie
Published: February 2005

An unusual organelle in the oocytes of the marine mud snail Ilyanassa obsoleta is described and called a polymerosome, because of its several components. Polymerosomes appear at the beginning of vitellogenesis and persist, in part, through postvitellogenesis. The persistent part is similar to an organelle that has been described by other workers in the vegetal region and the polar lobe of the Ilyanassa egg.
Histophysiological studies on the corpus allatum during prepupal diapause in Monema flavescens (Lepidoptera)
Authors: Takeda Naokuni
Published: February 2005

The appearance of the corpus allatum, the central endocrine gland of diapause, was examined histologically in the slug moth prepupae, Monema flavescens (Lepidoptera)

Before beginning of diapause, the secretory cells of the corpus allatum increase in size with the enrichment of the cytoplasm in quantity and in number of organelles, while RNA synthesis also starts. As diapause progresses, the secretory cells have many large unstained vacuoles in the cytoplasm, which were demonstrated to contain some substances of lipoidal nature. It is not clear that the substance is juvenile hormone itself or a material related to juvenile hormone. Agranular ER is the most characteristic organelle connected with mitochondria and situated around the vacuoles during diapause. Electron micrographs show that agranular ER and mitochondria have an essential role for the production of juvenile hormone.

The function of the corpus allatum during diapause and the relationship between juvenile hormone and diapause are discussed.
Blood circulation in the balanomorph barnacle, Megabalanus californicus (Pilsbry)
Authors: Burnett Bryan R.
Published: February 2005

Compared to the lepadomorph barnacles, the morphology of hemolymph circulation in the balanomorphs is poorly known. This report on Megabalanus californicus is the first detailed description of blood circulation in a balanomorph barnacle.

In Megabalanus hemolymph circulates in a similar pattern to that seen in lepadomorphs. However, Megabalanus shows major differences. (1) The mantle and associated structures ( =peduncle in the lepadomorphs) shows no large sinuses and blood is directed to branchiae via well defined vessels. (2) The gut is entirely invested with vessels from the distributive system (except for the proctodaeum). (3) A large sinus in the thoracic region (thoracic sinus) has no similar structure in the lepadomorphs. (4) The prosomal sinus is reduced and positioned dorsally. (5) The rostral sinus is larger than any found in the lepadomorphs and receives a substantial amount of blood from the peripheral circulation.

The smallness of the prosomal sinus in Megabalanus probably is due to lack of a contractile peduncle. In the lepadomorphs the prosomal sinus likely serves as a storage sinus for hemolymph when the peduncle is contracted.
The diversity of neurosecretory cell types in the cave tick Ornithodoros tholozani
Authors: Gabbay Shoshana , Warburg M. R.
Published: February 2005

Neurosecretory cells are arranged in 16 NSC centers in the different regions of the brain of O. tholozani. The component cells belong to 13 different types, of which five types are paraldehyde fuchsin positive and the remaining types are negative. Three of these cell types are here described for the first time. Some of these NSC show an affinity to certain localities inside the brain. Cells comprising a neurohaemal organ were found near the exit of the esophagus.
A scanning electron microscopic study of differentiation of the digital pad in regenerating digits of the kenyan reed frog, Hyperolius viridiflavus ferniquei
Authors: Richards Christina M. , Carlson Bruce M. , Connelly Thomas G. , Rogers Sherry L. , Ashcraft Elizabeth
Published: February 2005

Newly metamorphosed Kenyan reed frogs, Hyperolius viridiflavus ferniquei, are able to regenerate amputated digits. The terminal digital pad is also completely reformed. Differentiation of the regenerating digital pad was studied by scanning electron microscopy. External differentiation of the digital pad began late in the second postamputational week with the appearance of small patches of specialized epidermal cells on the ventral surface of the regenerating digit. The differentiation of the pad spread out radially until late in the fourth week, when its overall shape approximated that of the normal digital pad. The appearance of patches of digital pad epidermis on the ends of spike regenerates arising from the forearm was also confirmed.
The relation between size of motoneurons and their position in the cat spinal cord
Authors: Clamann H. P. , Kukulka C. G.
Published: February 2005

Experiments were performed to test whether motoneurons in the plantaris and medial gastrocnemius muscles of the cat are arranged in the spinal cord according to their sizes. It was found that motoneurons are randomly distributed with respect to size in their motor nuclei. Evidence is also presented that motoneuron density in these pools is irregular, and that there is considerable variability of position of medial gastrocnemius and plantaris motor pools from animal to animal.
The coelomocytes of the earthworm Lumbricus terrestris: morphology and phagocytic properties
Authors: Stein Elizabeth , Avtalion Ramy R. , Cooper Edwin L.
Published: February 2005

The coelomocytes of Lumbricus terrestris have been classified and described, based on Wright's stained preparations and on living cells. The five major categories consist of basophils, acidophils, neutrophils, granulocytes and chloragogen cells. Both the acidophil and chloragogen cell groups contain two subgroups. Granulocytes also exhibit heterogeneity with respect to staining properties of granules. Some possess acidophilic granules, some basophilic granules, and others contain both types. Granules of acidophils have been observed to be occasionally excreted from the cells. All cell types, with the exception of chloragogen cells, produce pseudopodia and are capable of phagocytosis, a vital component of the earthworm's immune response.
Thyroxine‐induced gill resorption in the axolotl (ambystoma mexicanum)
Authors: Hackford Alan W. , Gillies Concettina G. , Eastwood Catherine , Goldblatt Peter J.
Published: February 2005

Normal gill structure and thyroxine induced resorptive changes were studied in Ambystoma mexicanum. The gill is normally composed of a mesenchymal core covered with a multilayered epithelium. The general architecture is simpler than that of the teleost and elasmobranch, but the vascular arrangement is analogous. There are three basic cell types in the epithelium: a characteristic epithelial cell containing tonofibrils and mucus, a ciliated cell with an ultrastructure similar to that of the chloride cell, and the mucin‐filled Leydig cell. The basal lamella and mesenchymal tissue appear typical of amphibians.

Cytologic changes during thyroxine induced gill resorption varied with cell type. Some epithelial cells demonstrated a cytoplasmic response with swelling of mitochondria and rough endoplasmic reticulum and late, lytic nuclear changes, while others remained viable and went on to cornify. Ciliated cells showed early changes in nuclear chromatin pattern followed by rapid, progressive dilatation of endoplasmic reticulum. Leydig cells sustained variable changes leading to collapse of the perinuclear mucus, and cells of this type were absent in mature epidermis. Early basement membrane changes included widening and reduplication of the adepidermal membrane followed by morphologic fraying of collagen plies. There is no cytologic evidence to suggest that autolysis plays a major role in gill tissue dissolution.

Resorption involved the maintenance of structural integrity in the face of diminishing physical dimensions. The epithelium became cornified, the basement lamellae dissolved, and the mesenchymal tissue was resorbed through action of macrophages in an orderly distal to proximal direction.
Regeneration in Hydra viridis with multiple‐gastric region grafts: Reversal of the middle piece
Authors: Shostak Stanley
Published: February 2005

The results of reversing the polarity of the middle gastric region in Hydra viridis with multiple‐gastric region grafts (3grp animals) are contrasted to previously reported results on comparably elongated animals (3g animals) whose middle gastric regions retain their original polarity. The middle gastric regions of 3grp animals are also bisected (the animals are hemisected) at various times after grafting. Compound heads and compound feet form at the proximal and distal graft borders, respectively, in nearly all 3grp animals. The regeneration of structures at points is a built‐in property, not influenced by reversing the polarity of pieces during grafting. Regeneration is accelerated when comparable wound surfaces are brought together by grafting with reversed polarity. Graft rejection is influenced by the total length of an animal and distances from terminal structures, but not the polarity of pieces. Budding is also influenced by total length and distance, but is dependent on polarity and diminished by head regeneration. When fresh wound surfaces are made on the middle piece of 3grp animals, an initial refractory period, during which head and foot (but not budding region) regeneration is inhibited in about half the animals, is followed by an indefinite period in which head and foot regeneration is permitted (and budding region regeneration prevented). Hemisection does not interfere with the regeneration of compound structures already in progress. These results are interpreted in terms of theories of competence, negative dominance, threshold (positional value), inhibition (positional signal), and induction (positive or constructive dominance, stimulation or enhancement).
Fine Structure of the A Cells of the Pars Intercerebralis of Normal and Gamma‐irradiated Female Milkweed Bug, Oncopeltus fasciatus (Heteroptera: Lygaeidae)
Authors: Unnithan G. C. , Nair K. K.
Published: February 2005

Neurosecretory A cells in the pars intercerebralis of O. fasciatus were identified at the ultrastructural level. Fine structural study of the A cells of female insects during the period of production of the first batch of eggs revealed that these cells undergo qualitative and quantitative changes during the first eight days of adult life. The A cells appear to be inactive in the newly emerged females. There is a significant depletion of neurosecretory granules (NSG) in the perikarya in the 2‐day‐old females followed by an increase and decrease in the 4‐ and 6‐day‐old females, respectively. The A cells in the 8‐day‐old females showed an accumulation of NSG. The mitochondrial population increases after adult emergence reaching a peak in the 4‐day‐old females, and then declines gradually in the subsequent age groups. The effect of sublethal dose of gamma radiation on the ultrastructure of the A cells was also investigated. Radiation damage is evident as early as four hours after irradiation with 10 kR. There is considerable swelling of the lysosomes and the membrane system in the A cells of irradiated insects. Synthetic activity of the A cells, based on the distribution of the endoplasmic reticulum, Golgi complex and mitochondria, as well as release of the NSG are apparently inhibited after irradiation. Radiation‐induced damage becomes more conspicuous as post‐irradiation interval increases. It is surmised that the damage to the A cells might have contributed at least in part, to the failure of yolk deposition in the irradiated insects.
Observations on the vasculature of the reproductive tract in some Australian marsupials
Authors: Lee C. S. , O'Shea J. D.
Published: February 2005

The origin, distribution and structure of the blood vessels of the female reproductive tract and the testis of the brush possum (Trichosurus vulpecula) were studied using latex and silicone rubber casting and histological techniques. Latex casts of the vessels of the female tract were also studied in five macropod species – Macropus giganteus, M. eugenii, M. agilis, Megaleia rufa and Thylogale billardierii, and in the common wombat (Vombatus ursinus).

The female reproductive tract in the brush possum was supplied and drained by four major sets of paired vessels – ovarian, cranial urogenital, caudal urogenital, and internal pudendal arteries and veins. These vessels formed substantial anastomoses with one another on each side of the midline, and also across‐the‐midline anastomoses. The proximal part of the ovarian artery ran in close apposition to the ovarian vein, which received one or more large uterine branches. In its distal protion the ovarian artery gave rise to a leash of small, tortuous ovarian branches, which wound around and between the plexiform ovarian veins.

The testicular arteries and veins in this species also ran in close apposition to one another. Both arteries and veins branched into many smaller, mildly tortuous, parallel vessels in the spermatic cord, which reunited before entering the testis.

The blood vessels of the reproductive tract in all of the macropod species studied, and in the common wombat, were basically similar to those of the brush possum.

The intimate structural relationships between ovarian arteries and veins, and their ovarian branches, in these marsupials are suggestive of specializations for counter‐current exchange between venous and arterial blood. However, in contrast to those of the testicular vessels where heat exchange is a demonstrated function, their physiological significance remains unknown.
Inhibition and axial deviation of limb regeneration in the newt by means of a digit implanted into the amputated limb
Authors: Carlson Bruce M.
Published: February 2005

This research was designed to follow up the observation of Thornton and Kraemer ('51) that regressed, denervated limbs of Ambystoma larvae will not regenerate upon reinnervation if all digits on the limbs were not completely resorbed. The object of this experiment was to determine whether the presence of an apical structure, protruding past the amputation surface, would affect the regenerative process. Both forearms of adult newts were amputated midway between the elbow and the wrist. One limb served as a normal regeneration control, and in the other limb the third digit from the removed hand was implanted in place of the removed radius, so that the three distal phalangeal segments protruded past the plane of amputation. Blastema formation in the experimental limbs was delayed by several weeks as compared with control limbs. Approximately one third of the experimental limbs did not regenerate. The regenerates that did form were strongly deviated (45–90°) radially from the longitudinal axis of the limb. Experimental analysis showed that the delay in regeneration is due largely to the projecting part of the digit. The radial deviation of the regenerates is not due to the digital implant, but rather to the removal of the radius. Trauma alone does not account for this phenomenon.
The ultrastructure of the anal vesicle of the parasitoid, Microplitis croceipes (Hymenoptera:Braconidae)
Authors: Edson Kathryn M. , Norton William N. , Vinson S. Bradleigh
Published: February 2005

The fine structural characteristics of epithelial cells of the anal vesicle in the hymenopteran parasitoid, Microplitis croceipes (Cresson), are similar to those of transport cells. Apical and basal infoldings, an abundance of mitochondria, ribosomes, rough endoplasmic reticulum, Golgi complexes and pinocytotic vesicles all indicate a transport function for these epithelial cells. The medial portions of both Malpighian tubules located within the anal vesicle also were examined and on the basis of morphology appear to be active. These observations support earlier physiological data which indicate that the anal vesicle functions in absorption of nutrients and excretion.
Ultrastructural study of the relations between Leptomonas oncopelti (Noguchi and Tilden), protozoa trypanosomatidae, and the rectal wall of adults of Oncopeltus fasciatus dallas, hemiptera lygaeidae
Authors: Laugé Ginette , Nishioka Richard S.
Published: February 2005

A laboratory colony of Oncopeltus fasciatus was found to be infected by Leptomonas oncopelti. The flagellates form a carpet attached to the cuticular intima of the rectal glands of adult bugs. The epithelial cells of these glands are characterized by infolded apical plasma membranes associated with mitochondria; the overlying cuticular intima shows endocuticular canals. The Leptomonas are attached by hemidesmosomes, located most often at the tip of the flagella. The Protozoa multiply by budding and the resultant straphangers cling to the parental flagellum. Adhesion of the flagellates to the cuticular lining is so strong that detaching flagellates carry with them the outer part of the epicuticle. Epicuticle repair presumably occurs through the endocuticular canals.
Spermatogenesis and spermiogenesis in Ascaris lumbricoides Var. suum
Authors: Goldstein Paul
Published: February 2005

Reorganization of the prophase I nucleus marks the beginning of the first meiotic division. A pair of centrioles is present at each pole at metaphase I and mitochondria are not observed in the spindle area. A chromosomal pellicle, which resembles a kinetochore plate but has no apparent association with microtubules, surrounds each autosome at metaphase I and II. The sex body lags behind the autosomes at anaphase I and segregates differentially to one daughter cell. Mitochondria and a pair of centrioles are present in the spindle during the second meiotic division. Localized condensation of chromatin and fusion of the condensed chromatin of the secondary spermatocyte telophase nucleus results in a compact spermatid nucleus. Loss of spermatid cytoplasm is effected by the ejection of a cytophore vesicle.
The free swimming Pipa larvae, with a review of pipid larvae and pipid phylogeny (Anura: Pipidae)
Authors: Sokol Otto M.
Published: February 2005

This paper describes the morphology of the free swimming Pipa larvae, compares them with Xenopus, Hymenochirus, and to some extent, Rhinophrynus larvae, and presents a morphological diagnosis of pipid larvae.

Pipa and Xenopus have very similar chondrocrania. Hymenochirus is superficially different but has the same diagnostic features. The differences appear related to its small size and predatory habitus. Other aspects of anatomy, especially the filter apparatus are very different in each genus. The filter apparatus of Pipa is somewhat reduced and seems modified for the retention of relatively large (20+microns) particles. Similar adaptations may have been annectant to predations in Hymenochirus, which lacks a filter apparatus.

However, varying states of seven character complexes, which cut across the varying ecology, show that there are two basic pipid lineages, each currently confined to Africa or South America, respectively. Recent finds of fossil South American Xenopus indicate that these two lineages separated before the continents did.

This does not warrant the recognition of two subfamilies because Xenopus and Hymenochirus are too different. Pseudhymenochirus is not an intermediate between them; it is a primitive Hymenochirus.

Eight character states separate pipid and rhynophrynid larvae.
Microscopic age changes in the frontal bone of the domestic rabbit
Authors: Copping Ronald R.
Published: February 2005

This study reveals age related changes in the microscopic structure of the paired frontal bone of the domestic rabbit. Undecalcified ground sections were prepared from anterior frontal bone slices removed from New Zealand White rabbits ranging from birth to 24 months of age. Included were 40 females, 4 males and 6 rabbits less than 14 days old of unknown sex. The ground sections revealed both qualitative and quantitative age changes. Qualitative changes include change in bone tissue types and developmental processes, and presence or absence of primary and secondary osteones. Quantitative changes were measured by counting primary osteones in the outer table of each frontal bone half within 1.6 mm of the metopic suture. In this region, primary osteones were absent at birth, limited in number at 14 days and generally numerous between one and three months of age. In animals older than three months, numbers of primary osteones generally decreased with increasing age. No animals older than 16 months revealed primary osteones. Possible sources of variability in the relationship between observed primary osteone number and age include ability to recognize primary osteones, methods of sampling and processing bone slices, sex related differences and diseases afflicting specimen. Significance of this study includes increased knowledge of frontal bone growth and histology.
Fine structural analysis of the thoracic longitudinal stripes of Zaprionus vittiger (Diptera)
Authors: Walt Heinrich , Tobler Heinz
Published: February 2005

The structure of the longitudinal zebra stripes on the thorax of adult Zaprionus vittiger has been investigated by light‐, polarization‐, transmission electron‐, and scanning electron microscopy. Each stripe consists of a central white stripe of about 50 μm width and two lateral dark brown stripes about 30 μm wide. Three different types of trichomes occur: Very long bent trichomes of the grooved‐type, long bent trichomes of the crested‐type, and short straight trichomes. The central white stripe contains neither bristle organs nor short straight trichomes but carries many long bent trichomes most of which are of the grooved type, contain two cavities and polarize the light in the polarization microscope. The dark brown stripes carry bristle organs and many trichomes of the short and straight‐type. Bent trichomes of the crested‐type are found on the whole zebra stripe at about equal frequencies; they contain no cavities and do not polarize the light. The cuticle of the dark stripes is underlain by pigment cells. It is suggested that the pigment granules in the epidermal cells cause the dark color of the dark brown stripes, whereas the form and structure of the bent grooved type trichomes cause the white color of the central stripe.
Morphology of the epithelium in the alimentary tract of the larval lamprey, Petromyzon marinus L.
Authors: Hansen Susan J. , Youson John H.
Published: February 2005

The alimentary tract of the ammocoete of the lamprey, Petromyzon marinus L., is divisible into three morphologically distinct regions: the oesophagus, the anterior intestine, and the posterior intestine. The epithelium of the oesophagus possesses mucous, ciliated, and columnar cells and appears to be specialized for movement of food particles. The epithelium of the anterior intestine possesses secretory cells with numerous zymogen granules, ciliated cells, and columnar‐absorptive cells. Although some absorption occurs in the anterior intestine, the main function of this region seems to be the release of digestive enzymes and the continued movement of food particles. The epithelium of the posterior intestine is entirely comprised of columnar absorptive cells, namely tall (light and dark) columnar and low columnar, and the primary function of this region is one of absorption. The epithelium of the hindgut resembles that of the archinephric duct (Youson and McMillan, '71).

The morphology of the alimentary tract of ammocoetes suggests that some differentiation and renewal of cell types may occur in the epithelium of the three regions. Comparison of the alimentary tract of larval lamprey with that of other vertebrates indicates that the gut of the ammocoete represents a less specialized level of vertebrate development.
A topographical study of the distribution of end‐plates in the cutaneus pectoris, sartorius, and gastrocnemius muscles of the frog
Authors: Ypey D. L.
Published: February 2005

End‐plate distributions have been determined for three frog muscles of different morphology in order to relate end‐plate topography to spatial muscle structure and nerve branching. Koelle's cholinesterase technique was applied, both on whole muscles and frozen sections. The end‐plates of the short parallel‐fibered cutaneus pectoris muscle appeared to be located in short bands along the nerve branches. The nerve tree is restricted to a zonal area across the middle part of the muscle. Depending on the way the nerve branches, the end‐plate bands form innervation patterns, varying from one single continuous band to multiple distributed bands. In the latter case one frequently observes that different end‐plate bands do not run across the same longitudinal muscle fiber area, although the respective nerve branches run parallel across this area. The long parallel‐fibered sartorius muscle has a wider nerve tree and exhibits the same phenomenon for close parallel nerve branches, but end‐plate bands along parallel nerve branches far apart cover the same muscle fiber area. The end‐plate distribution in the bipennate, short‐fibered gastrocnemius is zonal throughout the muscle except in certain compartments containing tonic fibers. The end‐plate zone centers around the inner aponeurosis about half‐way between the muscle tendon junctions of the fibers and is visible only at the muscle surface where muscle fibers run over their entire length at that surface. The results are of general use in the electrophysiology of neuromuscular transmission because they illustrate how in certain twitch muscles neuromuscular morphology may help to localize end‐plates.
Body wall morphology of Pentapora foliacea (Ellis and Solander) (Bryozoa, Cheilostomata)
Authors: Carson Renate J. M.
Published: February 2005

The ascophoran Pentapora foliacea was studied from epoxy sections of skeletal and soft (hard‐soft) tissues. The basal wall is double, indicating the colony grew as two independent layers, back to back. The structure of the vertical walls and interzooidal communication organs indicates that zooids were budded in the usual way as in most encrusting cheilostomes. Secondary layers of the frontal wall are of acicular aragonite. The ovicell develops as a flattened cuticular bladder in early ontogeny; the aragonitic layer of the frontal wall later engulfs it. A median vesicle, an evagination of the vestibular wall, is present but the eggs may be supplied with sufficient yolk to nurture the embryo. The overall ovicell structure is similar to that of hyperstomial ovicells in other cheilostomes.
The fine structure of the salivary glands in the cockroach Gromphadorhina portentosa: Secretion
Authors: Dailey Patrick J. , Crang Richard E.
Published: February 2005

Secretion in the salivary glands of Gromphadorhina portentosa involves three cell types: parietal cells, secretory cells, and duct cells. The organization and role of the parietal and secretory cells are here considered. Parietal cells have numerous mitochondria, indicating an active metabolic role and the subsequent production of ATP. Plasma membrane invaginations and intracellular ductules containing microvilli appear to function in the absorption of solutes from the hemolymph and finely‐tapered ductules. Secretory cells contain abundant rough endoplasmic reticulum, the three forms (stacked, vesicular, and diffuse) of which appear to develop sequentially during maturation. Secretory vesicle formation is asynchronous between adjacent secretory cells, and apparently the large vesicles often coalesce. The secretory vesicles also show differing degrees of electron density, indicating distinct biochemical composition.
Studies on the mid‐gut of the desert locust Schistocerca gregaria. II. Ultrastructure of the muscle coat and its innervation
Authors: Anderson M. , Cochrane D. G.
Published: February 2005

The fine structure of the mid‐gut musculature of the desert locust, Schistocerca gregaria is described and compared with that of the visceral muscles of other species. The gross morphology and fine structure of the nervous system which supplies the mid‐gut muscle fibres is described.
Structure of the integument in Paranthessius anemoniae claus, a copepod associate of the snakelocks anemone Anemonia sulcata (Pennant)
Authors: Briggs Richard Peter
Published: February 2005

The integument of Paranthessius anemoniae has been studied with light and electron microscopy. A cuticle with clearly defined epicuticular, exocuticular and endocuticular regions overlies a cellular hypodermal layer. The distribution of carbohydrate, lipid and protein components of the cuticle were demonstrated histochemically. Parabolic striations in oblique sections of cuticle suggest that its molecular architecture fits a “twisted sheet” theory proposed for other species.

Arthrodial membranes at body and limb joints have a homogeneous structure, lacking exocuticle and endocuticle. Subcuticular glands appear to secrete substances thought to be responsible for the immunity which Paranthessius seems to have to the nematocysts of its host. Small hairs, situated in cuticular cups which occur over the dorsal body surface are considered to function as rheoreceptors.
Coelomic pouch formation in the starfish Pisaster ochraceus (Echinodermata: Asteroidea)
Authors: Crawford Bruce J. , Chia F. S.
Published: February 2005

The process of coelomic pouch formation in Pisaster ochraceus was studied with light microscopy, transmission and scanning electron microscopy and time‐lapse cinemicrography as well as with the drug cytochalasin B. As in most asteroids, the paired coelomic pouches of Pisaster ochraceus are formed from outpocketing of the archenteron.

Arrays of 50 Å microfilaments are found in the presumptive coelomic pouch cells at the apex of the archenteron as well as in the filopodia of the mesenchyme cells. Both cell types undergo active movements throughout the entire process. Treatment of embryos with cytochalasin B (CCB) during coelomic pouch formation results in the loss of cell movements and the regression of the coelomic pouches; this is accompanied by the loss of microfilament arrays in both cell types. Cell movements and microfilament arrays reappear on removal of CCB and coelomic pouch formation resumes.

Our evidence suggests that the microfilaments in the presumptive coelomic pouch cells provide the main force for the outpocketing movement. The major role of the microfilament arrays in the filopodia of the mesenchyme cells associated with the coelomic pouches is to determine the definitive shape and location of the pouches.
A histological study of the long‐term response to trauma of squamate integument
Authors: Maderson P. F. A. , Baranowitz S. , Roth S. I.
Published: February 2005

Scale neogenesis following excision of pieces of skin of various sizes and shapes has been studied in several squamate species. In small wounds, neogenesis does not occur, the wound region contracts, and increased areas of hinge differentiation are seen. In large wounds, the time taken for neogenesis to occur, and the size, shape, distribution, and number of the reformed units, are variable. We confirm previous reports that neogenesis accompanies a renewal phase of the shedding cycle, and suggests that this is because both types of morphogenesis require germinal stability.

All types of trauma thus far studied show the initial formation of a hyperplastic wound epithelium with the histological characteristics of a normal α‐layer: such tissues are the basis for physiological barrier functions. The mechanical functions of the skin can be fairly adequately restored even by abnormal neogenic scales. The observed variability in the process of scale neogenesis, and the final form of the individual units, are argued to be the result of mechanical factors impinging on the differentiating tissues.
The relationship of a monoamine fiber system to a somatosensory tectal projection in the salamander Ambystoma tigrinum
Authors: Gruberg Edward R. , Solish Samuel P.
Published: February 2005

After hemisection of the spinal cord and medulla oblongata, a projection has been traced to the inner half of the tectal white of the tiger salamander, using Fink‐Heimer degeneration staining. By microelectrode recording it was found that the tectal projection forms a topographic somatosensory map of the contralateral half of the body. This map is in register with the overlying retino‐tectal visual projection. Using the Falck‐Hillarp technique, it was found that the somatosensory tectal input is associated with yellow‐fluorescing 5‐hydroxytryptamine fibers.
Reinforced tracheoles in three firefly lanterns: Further reflections on specialized tracheoles
Authors: Ghiradella H.
Published: February 2005

The structures of the lantern tracheoles of three genera of flashing fireflies are compared. All three genera have stiff, reinforced tracheoles which resist folding or collapsing under conditions which flatten more typical tracheoles. This common specialization supports the hypothesis that the tracheoles play a major role in flash control in these fireflies, especially as the morphological basis of the stiffening is different in the three genera. Study of the tracheoles of other tissues reveals that there is great variety in structure and flexibility of these vessels from tissue to tissue and organism to organism, suggesting that tracheolar specialization may be a general phenomenon, with the fine structure of these air tubes being tailored to the particular demands and conditions of the tissues in which they are found.
The fine structure of Gromphadorhina portentosa salivary glands:duct transport system
Authors: Dailey Patrick J. , Crang Richard E.
Published: February 2005

The gross external morphology of the salivary glands of Gromphadorhina portentosa is described from light, scanning, and transmission electron microscopic observations. Various techniques, such as cryofracturing and epoxy‐fracturing followed by plastic removal, were employed. Internally, the transportation system is characterized by a cuticle‐lined lumen bordered by duct cells. The duct collects secretory products, some of which are reabsorbed by duct cells. Products are transported to intercalary ducts and eventually to the hypopharynx and/or salivary reservoirs. Transmission electron micrographs demonstrate distinctive morphological differences between duct cells bordering ductules and those which line expanded regions of the duct. Duct cells which surround ductules have a microvillous‐lined apical border in which the cuticular coat of the lumen may be only partially developed. Duct cells in other regions may retain microvilli, or the apical plasma membrane may invaginate and vesiculate. In some cells the apical region has neither microvilli nor invaginations, but possesses two morphologically different forms of microtubules. Some duct cells are characterized by the presence of lamellar bodies in the nuclear region and/or collagenous material above the basal lamina in the area where the acinar duct becomes confluent with the intercalary duct. The plasma membranes between adjacent duct cells within acini become convoluted, forming loops filled with cytoplasm. These loops, along with contact and septate desmosomes formed between membranes, may serve dual functions: adherent mechanisms between cells and/or transportation of materials between cells.