bluuebunny/crossref_metadata_2025 huggingface dataset:
The morphogenetic movements at the lower surface of the blastodisc in salmonid embryos
Authors: Ballard William W. , Dodes Lance Meredith
Published: June 2005

Patterns of hitherto undescribed morphogenetic movements have been found in Salmo gairdneri and Salvelinus fontinalis by removing samples of blastodiscs from their yolk spheres at intervals of several hours and inspecting their lower surfaces. Before onset of epiboly, the former species usually produces no pregastrular subgerminal cavity, but the latter usually produces one or several, with wide variation. In both species the inner blastomeres consolidate from an earlier dispersed and migratory condition, forming a coherent flattened sheet 6 to 10 cells thick before active epiboly begins.

As the first evidence of polarity in the salmomd embryo, one sector of the blastodisc becomes condensed and slightly thickened. Then a broad central area of the disc rapidly thins out as a result of two types of movement: (1) large numbers of cells disengage from the under surface of the condensed blastodisc, and they migrate away from the center as individuals and small groups; (2) the rest of the internal cells engage in a similar centrifugal movement toward the germ ring and the embryonic shield, but as a coherent sheet, sliding just within the cellular envelope.

Some, perhaps all, of the disengaged cells of the first group are slowly gathered into the endoderm sheet. The coherent cells of the second group accumulate in germ ring and embryonic shield, where they become split temporarily into upper and lower sheets, the former adhering to the external layer, the cellular envelope, with which it forms the epiblast, and the latter associating with the disengaged cells as the hypoblast.

The first internal sign of axis formation is a hitherto undescribed nubbin of cells attaching to the yolk syncytium at one sector on the inside of the blastodisc rim. The nubbin cells take no further part in the epibolic spread of the disc. It is suggested that they from an anchor for the later convergence movements from right and left, and that the whole pattern of movements from then on may be controlled by a gradient of increasing cell adhesiveness that spreads from them as a center. These nubbin cells have never been at the surface of the blastodisc. They neither invaginate nor migrate forward. They may represent the prechordal plate.
Sex hormone induction of sex reversal in the goldfish and evidence for male heterogamity
Authors: Yamamoto Toki‐O , Kajishima Takao
Published: June 2005

Methyltestosterone and estrone were administered orally to fry of the goldfish, Carassius auratus, daily for two months; thereafter, they were raised on a normal diet. All but one of the methyltestosterone‐treated fish developed into males, while all estrone‐treated fish developed into females. Of seven methyltestosterone‐treated males mated with normal females, six produced progeny in a 1 ♀:1 ♂ ratio and the remaining one produced only females. Of eleven estrone‐treated females mated with normal males, seven produced progeny in a 1 ♀:1 ♂ ratio and four yielded offspring in a ratio of 1 ♀ : 3 ♂. Induction of sex reversal in both directions by heterologous sex hormones was successfully accomplished. The sex ratios of the progeny of hormone‐treated goldfish provide evidence that the male is heterogametic (XY).
Water balance of whole animal, muscle tissue, and muscle cells in the prosobranch gastropod, Acmaea scutum
Authors: Webber H. H. , Dehnel Paul A.
Published: June 2005

The prosobranch limpet Acmaea scutum is found in both marine and estuarine environments. A number of parameters affect the water balance of this limpet. A. scutum has little control of total water content. Total water changes with season, size of animal, and salinity. Limpets from a marine environment, when immersed in experimental salinities for up to one week, are unable to regulate total body water. Estuarine limpets however, are able to regulate total body water in experimental salinities between 24 and 48 hours immersion. The ability to regulate water content between 24 and 48 hours is probably not important in the estuarine environment. Studies on the effect of field salinity on the water content of estuarine animals show that changes in field salinity of about 15% sea water resulted in significant changes in total body water.

Water content of muscle tissue and muscle cells of marine A. scutum, like body water values, conform when external salinity is changed. Estimates of intracellular water per unit of muscle tissue (using inulin space as extracellular space) changed with external salinity from 79.3% at 50% sea water to 57.7% at 125% sea water.
Effect of temperature on early embryological development of the zebra fish, Brachydanio rerio
Authors: Schirone Robert C. , Gross Leo
Published: June 2005

The early development of the zebra fish embryo, Brachydanio rerio (Hamilton) was studied under thermostatically controlled temperatures ranging from 13° to 35°C. Regular and successive cleavages and a distinct continuity of morphological features proceed regularly between 23° and 34°C. Embryos kept at temperatures above or below these limits did not complete embryogenesis. Embryogenesis up to late high blastula proceeded at the same rate of development over the temperature range of 24°C to 32°C.

Time‐lapse cinephotomicrography was utilized in a study of development from the one‐celled blastodisc to the closure of the blastopore, incubated in a modified Rose culture chamber. The number of abnormal embryos was constant over the range of temperatures from 23° to 34°C.
The effect of zinc on sea urchin morphogenesis
Authors: Timourian H.
Published: June 2005

Embryos of the sea urchin Lytechinus pictus were incubated for different periods of time in various concentrations of ZnCl2 in artificial sea water at pH 7.0 and 7.8. In general, zinc treatment restricts the development of endoderm and mesenchyme derivatives and zinc may be classified as an animalizing substance. The specificity of the zinc effects is analyzed considering the time during development that 65Zn is taken up by the embryo and the possible effects of zinc on protein synthesis, cell division and cell migration. The possibility that zinc exerts its effect non‐specifically as a toxic substance is explored. The animalizing properties of zinc may be the result of a non‐specific arrest in development at the time when the structures derived from the vegetal half are differentiating.
The development of the serosa in male embryos of the mealy bug, Pseudococcus obscurus Essig
Authors: Bregman Allyn A.
Published: June 2005

The development of the serosa or embryonic covering is described for males of the coccid, Pseudococcus obscurus Essig. The cells of part of this tissue are typical of males, having the paternal chromosome set heterochromatic and genetically inert. The cells of the remainder of the tissue have the chromosome contributions of both parents in the euchromatic state. Observations on cells undergoing reversal from the heterochromatic to euchromatic state are described. Euchromatic serosa cells (ESC) were selectively damaged or destroyed by (1) paternal x‐irradiation (PI) causing genetic damage to one set, (2) direct ultraviolet irradiation of ESC, and (3) interspecific mating to introduce foreign genetic information. The effects of these treatments on serosa composition were studied. Following PI, the fewer ESC were usually not accompanied by more heterochromatic serosa cells (HSC). After UV irradiation, the fewer ESC were consistently accompanied by extra HSC. Following interspecific mating, the hybrid ESC resembled those of the maternal species, Ps. obscurus, in number and size, but the HSC increased in number. Within almost all groups, regardless of treatment, a negative correlation between the numbers of ESC and HSC was found. The negative correlations and the UV results support an area compensation model for the completion of the serosa. The model is that a change in the total area of the ESC is accompanied by a compensatory change in the total area of the HSC. The results of PI may be consistent with the model since the size of individual ESC increased.
Effects of estrogen, progesterone, and testosterone on the pituitary and ovary of catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Goswami Shashi V.
Published: June 2005

Estradiol benzoate (EB), testosterone propionate (TP) and progesterone have been administered orally over 45 days during the late preparatory period to intact female catfish showing ovarian recrudescence. EB or TP treatment brings about a reduction in the size and number of basophils in the pituitary, and inhibition of vitellogenesis in the ovaries. Progesterone administration causes partial ovarian regression without significantly altering pituitary cytology. The sexually dimorphic urogenital papilla which is inconspicuous and nonmuscular in the female is unaffected by hypophysectomy and/or EB treatment. TP induces complete masculinization of the female papilla, whereas progesterone is only marginally effective.

EB injections over 15 days to intact catfish having ovaries containing yolk laden oocytes induce significant reduction in the number of pituitary basophils and extensive follicular atresia in the ovaries. Administration of EB to hypophysectomized catfish inhibits hypertrophy of the granulosa cells surrounding the yolky oocytes and thus delays the impending follicular atresia. The significance of these findings is discussed.
Isolation and characterization of ribosomal ribonucleic acid from the crustacean, Gecarcinus lateralis
Authors: Skinner Dorothy M.
Published: June 2005

Methods for the isolation of ribosomal RNA (rRNA) from three crustacean tissue have been devised. These include precipitation of rRNA from total RNA preparations with 1M sodium chloride, to remove both melanin and ATP, or solubilization in buffer containing EDTA, to chelate Mg++ and Ca++ which, when present, form alcohol‐insoluble complexes with ATP. By cosedimentation or gel electrophoresis with rRNA of known S20, w, the sedimentation constants of crab rRNA have been determined to be 28 S and 18 S. The base compositions of the 28 S and 18 S rRNA's have been determined. Muscle, midgut gland and epidermis have been found to have higher concentrations of rRNA in the premolt period than in the intermolt period, with the maxima corresponding to the periods of maximum protein synthesis. Premolt epidermis has the highest rRNA content of the three tissues.
RNA in Cecropia moth ovaries: Sites of synthesis, transport, and storage
Authors: Pollack Sylvia B. , Telfer William H.
Published: June 2005

Azure B staining of Cecropia moth ovarian follicles indicated that the pattern of RNA concentrations characteristic of vitellogenic oocytes is disrupted by a gross redistribution and dispersion, beginning with the final discharge of the cytoplasm of the nurse cells into the oocyte. The cytoplasmic redistribution is largely complete two days later when chorion formation begins, the germinal vesicle breaks down, and the first meiotic spindle forms.

At this stage the follicle contains 30 μg of RNA, of which 27 μg are in the follicle cells and only 3 μg in the oocyte itself. The proportionately large amount of follicle cell RNA apparently reflects the synthetic functions of these cells in the formation of yolk and the secretion of chorion. Of the 3 μg in the oocyte, only 1 μg is incorporated into the early embryo while the remainder is found in the yolk cells and serosa.

Autoradiography of follicles labeled with H3‐uridine either in vivo or by a “pulsechase” procedure in vitro indicated that, as in other polytrophic insect ovaries, the nurse cell nuclei are the most conspicuous source of oocyte RNA. The germinal vesicle incorporated labeled uridine in previtellogenic follicles. In vitellogenic and later stages neither a germinal vesicle nor a follicle cell contribution to oocyte RNA was detected by the procedures used.
Analysis of histogenesis and regenerative ability of denervated forelimb regenerates of Triturus viridescens
Authors: Powell Jeanne A.
Published: June 2005

Forelimb blastemata of the adult newt, Triturus viridescens, were denervated at three stages of regeneration and allowed to differentiate in the absence of nerves. Some of these limbs, after developing to specific regenerative ages, were subjected to hand amputations and second denervations. The central question posed was: if the blastema is allowed to differentiate in the absence of nerves, will the resultant limb upon reamputation at a more distal level be capable of initiating renewed regeneration as are aneurogenic larval limbs that have differentiated in the absence of nerves? The older the blastemata at the time of the first denervation, the greater was the incidence of continued morphogenesis. Preliminary histogenesis at the time of the first denervation did not insured continued morphogenesis, nor did complete absence of histogenesis prevent further development. Cartilage elements and muscle differentiated in nerveless regenerates, but both tissues lagged in development compared to those of the contralateral innervated limb. Muscle was reduced in amount, and some evidence indicated that it underwent degenerative changes if the nerveless state was maintained. None of the completely nerve‐free regenerates was able to reinitiate regeneration. Thus blastemal cells were not able to return to the embryonic level of independence of nerve supply under the conditions of the experiment.
Effects of 6‐azauridine on the embryonic cells of Xenopus laevis, with special reference to nucleolar ultrastructure
Authors: Sameshima M. , Shiokawa K.
Published: June 2005

Effects of 6‐azauridine on isolated embryonic cells of Xenopus laevis were examined electronmicroscopically. It has been revealed that shortly after the treatment, when the rate of RNA synthesis became reduced, a unique ultrastrutural change occurred in the nucleoli: granular component greatly decreased in amount, while fibrous component retained a rather normal, though somewhat coalesced, net‐work structure. Four to six hours later, when inhibition in the syntheses of protein and DNA became apparent, the nuclear chromatin condensed and the nucleoli became a small round mass which consisted of fibrous component alone in some cells. Finally at the tenth hour, most cells showed pycnotic feature and the nucleoli were fragmented and frequently disappeared. At this time, endoplasmic reticulum and mitochondria were also deformed and decreased in number. The significance of the nucleolar alteration observed has been discussed.
Changes in epididymal spermatozoa and in the testes of rabbits after experimental cryptorchidism
Authors: Igboeli G. , Foote R. H.
Published: June 2005

Surgical cryptorchidism was induced in sexually mature rabbits by a scrotal incision approach or an abdominal approach, and the effects were observed for the next 14 days. Various combinations of ligatures on the corpus epididymidis and ductus deferens were employed to compare effects with and without restricted sperm movement.

Neither cryptorchidism nor epididymal ligatures reduced libido. However, ejaculate volume significantly decreased after 14 days of cryptorchidism (P < 0.05), and this may have resulted from a reduction in contributions by the epididymis as indicated by oligospermia.

Damage due to cryptorchidism was significantly more severe on sperm in the caput than in the cauda epididymidis. Four days of cryptorchidism caused an increase in percent of abnormal spermatozoa at all levels of the epididymis. It did not alter the percent of unstained sperm or fertility of sperm in the cauda epididymidis. Thus, uncapacitated sperm in the male at body temperature retain their fertilizing potential for considerably longer periods than capacitated sperm do in the female. Cryptorchidism for seven or more days resulted essentially in a complete loss of fertility of cauda sperm. Caput sperm usually were infertile initially, and after retention by ligation or after the elevation of temperature by cryptorchidism.

Testicular alterations were detected after one or more days of cryptorchidism, characterized by cellular sloughing, giant cells, absence of tubules in stage 8 and testicular and tubular shrinkage. Ligatures on the corpus also caused fluid and sperm accumulation and interfered with spermatogenesis. This fluid accumulation was associated with a significant increase in caput epididymal weights (P < 0.05).
The mesoglea of hydra. I. Physical and histochemical properties
Authors: Hausman Robert E. , Burnett Allison L.
Published: June 2005

The mesoglea of Hydra serves both as a skeleton and as a substratum for cell migration. These functions are made possible in Hydra pseudoligactis by a system of fibers that run along the body column, parallel to the oral‐aboral axis, and perpendicular to the oral‐aboral axis. The fibers are either a mucoprotein or a close spatial arrangement of protein and polysaccharide. They are 0.3 μ in diameter and contain an elastin‐like and collagen‐like protein.

Spaced along the fibers are acid mucopolysaccharide‐like particles, 0.7 μ in diameter, which appear to serve a structural or supportive function. Between the fibers are 2.4 μ diameter holes for extension of epithelial cell processes. The remainder of the mesoglea consists of an amorphous gel with a collagen matrix.

The physical arrangement of the fibers allows the normal movements of hydra and could also control the direction of cell migration. The arrangement of fibers may be a dynamic system under the control of an enzyme.
Hormonal dependence of tail regeneration in the lizard Anolis carolinensis
Authors: Licht Paul , Howe Nathan R.
Published: June 2005

Removal of the pars distalis several days before the amputation of the tail in Anolis carolinensis delays blastema formation and virtually abolishes tail regeneration. Hypophysectomy on, or several days after, tail amputation does not delay blastema formation but tail growth is largely abolished. If lizards are hypophysectomized after the blastema has formed and the tail has begun to elongate, the rate of tail regeneration is greatly reduced within a few days.

Injection of a combination of adenohypophysial hormones (growth hormone, prolactin, gonadotropin, and thyrotropin) restored tail regeneration to near normal levels in hypophysectomized lizards.

A quantitative relationship was evident between the amount of pars distalis removed and the rate of tail regeneration. However, there was no apparent relationship between the region of the gland removed and regeneration, indicating that tail regeneration is probably dependent on a combination of several pituitary hormones.
Some aspects of tail regeneration in the lizard, Anolis carolinensis. I. A description based on histology and autoradiography.,
Authors: Cox Prentiss G.
Published: June 2005

The histology of the tail and its autotomy planes in Anolis carolinensis follows the same basic plan as that described for other lizards. Variations in detail which are of importance to the present paper are described. The normal regeneration process was studied using histologic and autoradiographic techniques. These studies suggest: (1) that the muscle makes little if any contribution to the regenerate, (2) that the source of cells for the regenerate is primarily from the various connective tissue elements and (3) that the tail has no apical accumulation blastema. It is proposed that the term blastema as applied in amphibian limb regeneration cannot be applied in lizard tail regeneration. The growth of a normal regenerate results from extensive interstitial growth in the differentiating tissues and from subapical growth in the less differentiated areas of these tissues.
Staining of intercellular material in reaggregating chick liver and cartilage cells
Authors: Khan Talat , Overton Jane
Published: June 2005

Lanthanum has been used to study the immediate cellular environement in reaggregating liver and cartilage cells and in mixtures of the two cell types in order to permit visualization of intercellular material by electron microscopy. Lanthanum staining material was absent from the cell surface in freshly isolated cells but was present between cells in all stages of reassociation. The stained material characteristic of cartilage and liver cells differed. Thus in mixed reaggregates it can be demonstrated that from early stages in the process cells are exposed to different sorts of cell products. Enzymatic treatment of reaggregates suggested that lanthanum may stain mucopolysaccharide.
Age‐dependent changes in alcohol dehydrogenase in Drosophila
Authors: Dunn G. R. , Wilson Thomas G. , Jacobson K. Bruce
Published: June 2005

Drosophila melanogaster alcohol dehydrogenase undergoes changes both in specific activity and in the isozyme forms during the course of development of larvae and adults. Specific activity is high in the larva, low in the pupa, high again in the young imago, and declines gradually thereafter. One of the five forms of alcohol dehydrogenase, ADH2, appears only for one day immediately preceding pupation and is present from days 1–12 of adult life; ADH3 and ADH5 are present at all ages. These results are interpreted to mean: (1) alcohol dehydrogenase is physiologically regulated, (2) isozyme forms can be produced and removed and (3) a mechanism presumbly exists to do this.
The influence of a head graft on regeneration of the isolated postpharyngeal body section of Dugesia tigrina
Authors: Ansevin Krystyna D.
Published: June 2005

The influence on regeneration of a reversed head graft attached to the posterior end of the isolated postpharyngeal section of Dugesia tigrina was studied following removal of the graft after varying periods of time. After section‐graft association for as long as three days, the predominant effect of the graft was inhibitive: regeneration of the head was blocked first, position or reconstruction of the pharynx next, and elongation of the body arrested last. This appears to indicate the sequence of determinations of these structures and the times when they occur in normal morphallaxis of the isolated postpharyngeal section. Four days of section‐graft association appeared sufficient for the grafts' own inductions to occur in the section. Longer associations resulted in gradual, and ultimately complete reversal of polarity of the postpharyngeal section.
An ultrastructural study of lens invagination in the mouse
Authors: Wrenn Joan T. , Wessells Norman K.
Published: June 2005

Early lenses of mouse embryos were studied with the electron microscope to determine whether their cells contain organelles that can be causally related to the invagination of the lens placode. The cells of the placode and early lens cup are joined at their apical ends by junctional complexes. At the level of the zonula adhaerens, favorable sections show cytoplasmic filaments, 35 Å to 50 Å wide, arranged about the apex of a cell. Groups of filaments appear to originate on or near the plasma membrane and then to extend across the cytoplasm, parallel to the apical cell surface, to terminate on or near the plasma membrane some distance away. They are nearly always straight; in contrast, nearby lateral and apical cell membranes are twisted into irregular folds and projections.

We present a model to explain lens invagination in which the filaments are considered to be contractile. On the basis of their location in the cells and their presumed function, these organelles are proposed to be a major component in the mechanism that leads to early morphogenesis of the lens.
Activation of DNA replication in the iris epithelium by lens removal
Authors: Yamada Tuneo , Roesel Marion E.
Published: June 2005

The pattern of DNA replication during the initial stages of Wolffian lens regeneration has been examined by an autoradiographic study of tritiated thymidine uptake in zero to five‐day regenerates (Triturus viridescens). Scanning of complete sets of serial sections for each iris revealed the absence of labeled cells in normal, one‐, and two‐day iris epithelia, and a very infrequent occurrence of labeled iris epithelial cells in some three‐day regenerates. After this stage, cell labeling is seen in all iris epithelia. Cell labeling frequency increases markedly by four days, and is at a very high level in five‐day regenerates.

Further data indicate that labeling begins in the dorsal sector of the iris epithelium. By five days after lens removal, however, it reaches similar levels in dorsal, lateral, and ventral sectors. Thus, DNA replication is induced throughout the iris epithelium after lens removal, even though the lateral and ventral sectors of the iris epithelium do not participate in actual lens formation.

Comparison between the outer and inner laminae of the iris epithelium shows that during all stages studied the great majority of labeled cells are in the inner lamina.
Effect of blinding on reproductive and pelage cycles in the ferret
Authors: Rust Charles C. , Shackelford Richard M.
Published: June 2005

The effect of blinding on reproductive and pelage cycles in ferrets held outdoors under natural environmental conditions was investigated from October, 1966, to March, 1969. Blind female and intact male and female ferrets underwent the normal seasonal changes during this period. They became reproductively active and underwent the spring molt in March and April and became reproductively quiescent, molted and grew the dense winter pelage in September and October. Blind male ferrets exhibited a prolonged reproductive period which began in March and April, 1967, and extended through December. An incomplete pelage change and partial testicular regression occurred in most blind males in January and February, 1968. The same sequence of reproductive and coat changes was observed the following year. Blind and intact female ferrets mated to blind males bore normal litters.
Synchronous oogenesis in Engystomops pustulosus, a neotropic anuran suitable for laboratory studies: Localization in the embryo of RNA synthesized at the lampbrush stage
Authors: Davidson Eric H. , Hough Barbara R.
Published: June 2005

An investigation of several tropical frogs was undertaken in order to find species in which synchronous oogenesis takes place, so that the RNA synthesized at the lampbrush stage could be labelled and followed through early development. The reproductive cycle of Engystomops pustulosus was found to include both synchronous and asynchronous phases. Laboratory maintenance and induction of synchronous oogenesis in this organism are described. By using toads carrying out synchronous oogenesis, RNA synthesized during the lampbrush stage was shown to be retained through gastrulation. The pattern of new RNA synthesis in the embryo resembles that in other anurans. Radioautographs suggest that the distribution in the embryo of maternal RNA synthesized at the lampbrush stage is distinct from that of RNA newly synthesized by the embryo; the possible implications of these observations are discussed.
Lactate dehydrogenase isozymes of Pacific hake (Merluccius productus)
Authors: Utter F. M. , Hodgins H. O.
Published: June 2005

The lactate dehydrogenase isozymes of Pacific hake (Merluccius productus) are described. Evidence from molecular weight estimations and subunit recombination tests indicate that these isozymes have physicochemical properties similar to those of higher vertebrates. The predominant isozymes in most tissues appear to be composed of subunits coded at two loci. These subunits and loci were designated as A and B because of phenotypic similarities to isozymes coded by the LDH A and B loci of higher vertebrates; no attempts were made, however, to establish homologies between isozymes of Pacific hake and those of higher vertebrates. The predominant isozyme in extracts of skeletal muscle appears to be independent of those composed of A and B subunits and may reflect a third LDH locus in Pacific hake. In contrast to many species of teleost fish, no unique LDH isozymes were found in the eye.

Isozyme phenotypes reflecting two alleles, A and A′, were observed at the A locus. The frequency of the A′ allele was 0.01 in fish taken from the Pacific Ocean off the coasts of California, Oregon, and Washington and 0.25 in those from Puget Sound, Wash., it appears that the two populations are noninterbreeding. Gene‐frequency analyses of samples taken in various areas of Puget Sound indicate that the Puget Sound hake consist of a single breeding population.
Nucleic acid deficiency in the prothanic homozygous mutant of creeper fowl
Authors: Wallace H. , Clyman R. I. , Pierro L. P.
Published: June 2005

Prothanic Cp/Cp chick embryos synthesize ribosomal RNA to a lesser extent than control embryos, but incorporate radioactive uridine into RNA of a higher specific activity. Prothanic embryos contain less DNA, RNA and protein than control embryos at 72 hours. The deficiency of DNA is found equally in embryonic and extra‐embryonic Cp/Cp tissues. The deficiencies of RNA and protein are more marked in Cp/Cp embryos than in Cp/Cp extra‐embryonic tissue. These results, and similar observations on phenocopies, are considered to imply that the primary developmental defect of prothanic embryos concerns the extra‐embryonic circulatory system.
The fine structural organization of the sea nettle fishing tentacle
Authors: Burnett J. W. , Sutton J. S.
Published: June 2005

The fishing tentacle of the sea nettle (Chrysaora quinquecirrha) has four basic layers: an outermost epithelial layer, a muscle cell layer, a core of mesoglea and an innermost epithelial layer. The outermost epithelium contains three different cell types: (1) supporting cells, (2) nematocytes and (3) mucous cells. Apical cellular processes of smooth muscle fibers extend into the outermost epithelial layer whereas basal processes penetrate the mesoglea. The mesoglea contains randomly oriented fibrils (60–70 Å in diameter). Inner epithelial cells vary in morphology. Some cells contain mostly phagocytotic vacuoles while other cells have an abundance of rough surfaced endoplasmic reticulum.
Effect of pituitary hormones, androgens, and corticosteroids on the seminal vesicles of the castrate catfish, Heteropneustes fossilis (Bloch)
Authors: Nayyar S. K. , Sundararaj Bangalore I.
Published: June 2005

Δ5‐3β‐hydroxysteroid dehydrogenase activity (Δ5‐3β‐HSD) has been studied in the interrenal glands and the seminal vesicles of intact and castrate male catfish. The intensity of the enzyme reaction is about equal in the seminal vesicles of both groups, whereas the intensity of enzyme reaction in the cortical cells is more pronounced in the castrate than in the intact male.

The responses of the interrenal glands and the regressed seminal vesicles of the castrate catfish in the postspawning period to exogenous luteinizing hormone (LH), Δ4‐androstenedione (Δ4‐androst.), desoxycorticosterone acetate (DCA) and hydrocortisone acetate (HA) (experiment 2), and the effect of the LH, Δ4‐androst., DCA and HA, and prolactin (LtH) and growth hormone (STH), singly or in combination on the regressed seminal vesicles of the castrate catfish (experiment 3) have also been studied. The data indicate that both LH and Δ4‐androst. induce secretory activity in the seminal vesicles but they appear to act through different routes. Since LH brings about an increase in the nuclear diameters in cortical cells and Δ4‐androst. does not, it is felt that LH acts through the cortical cells of the interrenal glands while Δ4‐androst. acts directly on the seminal vesicles. Further, Δ4‐androst. can synergize with LtH and STH in inducing secretory activity in the seminal vesicles, whereas DCA and HA do not. These results, coupled with the fact that Δ5‐3β‐HSD activity is more marked in the cortical cells of the castrate than in the intact catfish, strongly suggest that following castration, the resulting high titers of gonadotrophin act on the interrenal cortical cells to produce androgens which, in turn, induce hyperactivity in the seminal vesicles.
The effect of actinomycin D on nucleolar formation in early Xenopus laevis gastrulae
Authors: Sameshima M. , Shiokawa K. , Kawakami I.
Published: June 2005

Electron microscopic examinations revealed drastic effects of actinomycin D on nucleolar formation in isolated cells of Xenopus laevis embryos. The nucleoli in newly isolated cells of early gastrulae were composed solely of a fibrous component. After culture for two to five hours in complete Stearns' solution without the antibiotic, a granular component appeared among the fibrous components in most of the nucleoli, which showed more elaborated structures. On the other hand, after being cultured for two hours in the presence of actinomycin D (l r/ml), by which inhibition of DNA synthesis was effected, all the nucleoli examined remained as spherical masses composed of fibrous component alone, lacking granular component. After five hours' treatment, inhibition of the synthesis of protein and DNA became biochemically detectable, and ultrastructural changes were observed in both the nucleoplasm and the cytoplasm: that is, fragmentation of nucleoli, condensation of chromatins and deformation of mitochondria. Relationships between the formation of nucleolar components and the RNA synthesis in amphibian embryogenesis are discussed.
Spectral sensitivities of color receptors in the compound eye of the cockroach Periplaneta
Authors: Mote Michael I. , Goldsmith Timothy H.
Published: June 2005

Intracellular recording from single retinular cells of a white eye mutant of the cockroach Periplaneta americana stimulated between 316 and 704 nm reveals the presence of two classes of cells. In the dorsal part of the eye they are present in approximately equal numbers. Both have resting potentials of about 40 mv; neither responds with spikes.

Ultraviolet receptors are maximally responsive at 365 nm (λmax); sensitivity falls steadily at longer wavelengths and is down two log units at 440 nm. The membrane responses of ultraviolet receptors usually consist of a large graded transient which can completely depolarize the cell, followed by a smaller and slower plateau of depolarization which lasts as long as the stimulus.

Green receptors have λmax at about 507 nm. A tail of sensitivity extends through the violet and near ultraviolet, but sensitivity falls steadily to the long wavelength side of the λmax, and is down two log units at 615 nm. The membrane responses typically consist of a graded transient and lack the later plateau.
Transplantation immunity in the axolotl (Ambystoma mexicanum) studied by blastemal grafts
Authors: de Both N. J.
Published: June 2005

To verify data in the older literature concerning the survival of allografts in the axolotl, a transplantation‐immunological study was carried out in this species. Animals were used from four randomly bred laboratory populations, partly related and partly unrelated. Tolerance for blastemal allografts was shown at 20°C within two of the populations. In one of these the animals were provided with second and third set grafts, which were also tolerated. Allografts exchanged between larvae of related populations always showed prolonged survival. In contrast, grafts exchanged between non‐related populations were frequently rejected. In some cases this rejection was incomplete and was followed by regeneration. Axolotls which tolerated allografts nevertheless rejected blastemal xenografts from other urodelean species. It is concluded that neither immunological unresponsiveness of the host larvae, nor lack of antigenicity of the blastemal grafts is responsible for the prolonged survival of allografts, but that genetic relatedness is the main factor involved.
Physiological studies on supercooled killifish (Fundulus heteroclitus). III. Carbohydrate metabolism and survival at subzero temperatures
Authors: Umminger Bruce L.
Published: June 2005

The previously reported hyperglycemia induced in Fundulus heteroclitus by exposure to the subzero cold was investigated in more detail. It was found that the hyperglycemic response was elicited immediately when fish were transferred to water at − 1.5°C and that the striking increase in serum glucose was accompanied by a progressive depletion of hepatic glycogen. Muscle glycogen occasionally, but not always, showed a slight depletion after long exposure to the subzero cold. Serum glucose was not maintained at high levels indefinitely in the subzero cold. After hepatic glycogen was totally depleted, serum glucose levels began to drop. When serum glucose levels fell to normal, the fish began to die. Addition of glucose to the water elevated serum glucose levels and enhanced survival in the subzero cold. Winter fish, which produce higher levels of serum glucose in the subzero cold than do summer fish, survived the subzero cold almost twice as long as did summer fish. Serum nonglucose free carbohydrate levels were unaffected by the length of exposure to subzero temperatures. Liver protein levels were unaffected by temperatures from 20°C to − 1.5°C and muscle protein levels decreased slightly only after long exposure to the subzero cold.
Innervation and the regulation of acetylcholinesterase activity during the development of normal and dystrophic chick muscle
Authors: Wilson Barry W. , Kaplan Martha A. , Merhoff Wayne C. , Mori Susan S.
Published: June 2005

Two isozymes of acetylcholinesterase (AChE) in the skeletal muscles of the chick embryo decrease to very low levels after hatching. These isozymes have been shown to be maintained in fast twitch muscles, the superficial pectoral and biceps brachii, of birds homozygous for inherited muscular dystrophy. Histochemical studies are presented that associate these isozymes with diffuse AChE activity in the sarcoplasm of embryonic and dystrophic muscle fibers.

The hypothesis that neural activity inhibits the activity of the embryonic AChE forms in normal but not in dystrophic muscle after hatching was supported by the fact that biceps muscles of normal chicks denervated at two days still retained embryonic AChE activity when examined one month after denervation. In addition embryonic AChE forms reappeared within three days after denervation in muscles from month old chicks. One month after surgery, total AChE activity of denervated normal muscle was three to four times that of the controls. Moreover, unlike the normal, the AChE activity of dystrophic biceps muscle did not increase following denervation. Tenotomy of muscles from month old chicks had little effect on AChE activity.
Malate dehydrogenases and glutamate dehydrogenase in chick liver and heart during embryonic development
Authors: Greenfield Phyllis C. , Boell E. J.
Published: June 2005

The specific activity of malate dehydrogenase isozymes in cytoplasm and mitochondria of liver and heart have been studied throughout development in the chick. The properties of the isozymes in these tissues are similar to those reported for other tissues. During development, the pattern of the specific activity of the isozymes of liver differs from that of the heart. Activities of the mitochondrial matrix and cytoplasmic isozymes of liver are constant; in heart they increase but not to the same extent. In mitochondria, the activity of malate dehydrogenase varies in the same way as that of cytochrome oxidase. Like cytochrome oxidase, malate dehydrogenase is therefore a constant proportion enzyme. Glutamate dehydrogenase is found in significant amounts in the liver; it is localized in the mitochondrial matrix, and its specific activity remains constant throughout development. In contrast, glutamate dehydrogenase can be detected in the heart only after hatching.
Oogenesis in the suppressor2of Hairy‐wing mutant of Drosophila melanogaster. II. Nucleolar morphology and in vitro studies of RNA protein synthesis
Authors: Klug William S. , King Robert C. , Wattiaux Jean M.
Published: June 2005

Cytological studies of ovaries from Drosophila melanogaster homozygous for the third chromosomal, female sterile gene, suppressor2 of Hairy‐wing (su2‐Hw), demonstrate that the nurse cell components of the egg chambers are primarily affected. Both chromosomes and nucleoli show qualitative and quantitative differencies from wild type. The in vitro culturing of mutant and wild type ovaries in the presence of labeled RNA and protein precursors were examined using liquid scintillation counting and autoradiography. The results of the scintillation experiments showed the mutant ovary to be nearly equivalent to wild type in the synthesis of RNA, but only half as active in protein synthesis. The autoradiographic analysis revealed that during very short incubation periods, the mutant ovary was more active than wild type in the production of RNA but that the mutant RNA was unstable. The lowered protein synthesis by mutant ovaries was also apparent using autoradiography. Morphometric measurements of mutant and wild type nurse nucleoli indicate a severe reduction in su2‐Hw compared to wild type. These findings suggest that the instability of mutant RNA may be due to some deficiency of the ribosomes produced in the absence of the su2‐Hw+ allele. On the other hand, the autoradiographic studies using H3‐uridine revealed the presence of an extranuclear label in the mutant nucleus not apparent in wild type. The possibility exists, therefore, that the unstable mutant RNA is of extranucleolar origin and thus not ribosomal. In the absence of the su2‐Hw+ allele, translation occurs with poor fidelity leading to the suppression of the phenotypic effects of certain mutant genes. If the ribosomes are responsible for the instability of mutant RNA, normal ribosomes contributed by the heterozygous mother may allow the survival of homozygous mutant flies.
Sulfated extracellular matrix production in the embryonic heart and adjacent tissues
Authors: Manasek Francis J.
Published: June 2005

The incorporation of S35‐sulfate into tissues and extracellular matrix of chick embryos ranging in age from stage 8 (4 somites) to stage 12 (16 somites) was examined. 0.05 mc S35 were added to embryos grown in vitro and after appropriate incubation periods the embryos were fixed and embedded in plastic. Radio‐autographs of 1 μ plastic sections of embryos between stages 8 and 9 (4 to 9 somites) showed heavy S35 incorporation by all tissues, especially the notochord, neural fold and precardia. Between stages 10 (10 somites) and 12 (16 somites) the incorporation of S35 decreases in all tissues examined except the myocardium.

These results show that the production of sulfated extracellular matrix is not restricted to chondrogenic tissues in very young embryos, but that this function becomes selectively repressed as the embryo matures. This suggests that S35 incorporation during cartilage production by chondrogenic tissues (such as notochord) in older embryos involves the re‐expression of an earlier embryonic trait, rather than the acquisition of a wholly new capability.

The myocardium, on the other hand, continues to secrete a sulfated matrix even after the cells contain well developed myofibrils and become functional myocytes. Embryonic cardiac muscle is therefore a secretory as well as contractile tissue and the two “specialized” functions are not mutually exclusive.
Developmental genetics of the lactate dehydrogenase isozymes of fish
Authors: Whitt Gregory S.
Published: June 2005

Three genes (A, B, and E) encoding lactate dehydrogenase (LDH) subunits are shown to be present in fish by: (1) molecular hybridization, (2) allelic variants at two loci, and (3) kinetic, physical, and immunochemical studies. The same studies reveal that the E4 isozyme is closely related to the B4 isozyme. The E4 isozyme is usually synthesized in the regions of the nervous system concerned with vision. However, in some species the E4 isozyme is found in non‐neural tissues such as lens. The closely related B and E loci tend to simulataneously functional in the same retinal cells. The act of hatching by itself does not appear to act as the stimulus to E gene activation. The E subunit facilitates the assembly of A and B subunits into the same teramer. The developmental and tissue specificity of the function of the LDH E gene suggests that the distinctive physical properties and the kinetic behavior of the LDH E4 isozyme may play an important role in the metabolism of teleost vision.
The function of the middle ear in lizards: Crotaphytus collaris (lguanidae)
Authors: Wever Ernest Glen , Werner Yehudah L.
Published: June 2005

The anatomy of the middle ear is outlined for lizards in general and described in detail for Crotaphytus collaris (Iguanidae). By use of the alternating potentials of the cochlea, the general function of the middle ear in the reception of aerial sounds was determined by comparing the ear's sensitivity when the middle ear mechanism was intact with the sensitivity remaining when the columellar shaft was severed, thus eliminating the connection between the stapedial footplate and the more peripheral parts. This comparison was made under two conditions, with the sound applied in the usual way at the external auditory meatus and with the sound introduced through a tube sealed over the oval window. The loss of transmission observed under the first condition is complicated by the presence in the sound path of the nonfunctioning tympanic membrane and by an interaction of sound waves reaching both round and oval windows of the cochlea, but the second condition, in which these complications are avoided, reflects the true performance of the middle ear as a mechanical transformer. This transformer action was measured as 35 db on the average for tones between 300 and 4000 Hz, which is the region of best hearing for this lizard.

Further analysis of the operation of the tympanic mechanism was carried out by measurements of sensitivity before and after severing the connection between the internal process and the quadrate bone. These observations showed that the internal process makes little or no contribution to the ear's sensitivity. Other experiments performed with mechanical stimulation showed that the columellar system acts as a reduction lever, and the measurements gave a general indication of the amount of this lever action.

The pressure increase provided by the columellar lever, together with a still greater increase produced by the areal ratio between the effective surface of the tympanic membrane and the surface of the columellar footplate, can account in large part at least for the total transformer action. This action makes it possible for acoustic energy to be conveyed with great efficiency from the air to the relatively dense and stiff sensory elements of the cochlea. This problem of the matching of impedances between two media, and its solution by the use of a mechanical transformer, has long been studied in mammals, and especially in the cat, and the solution provided by the lizard's middle ear seems altogether as satisfactory as that provided by the structurally different ossicular mechanism of the mammals.
The structure of pigeon muscle and its changes due to tenotomy
Authors: Hikida Robert S. , Bock Walter J.
Published: June 2005

The tendon of the pigeon's biventer cervicis was sectioned, and the muscle examined histologically after varying post‐operative intervals. Tissues were prepared by routine histological procedures and stained in a number of ways. The results indicate that the fast fibers of the muscle have a faster onset of atrophy than do the slow fibers, but the slow fibers attain the same degree of atrophy in later stages. The onset of atrophic activity is characterized by a swelling of the nuclei and their migration away from the subsarcolemmal position in the twitch fibers. Slow fibers do not show any histological changes at this early stage (6 days). Vacuolization and lipomatosis begin at this stage, as well as some phagocytosis. These characteristics become more prominent as the tenotomy period increases, and connective tissue formation within the fibers can be seen, as well as ring fiber formation and other pathological conditions. The tenotomized muscles demonstrate conditions typical of various human muscle diseases, but differences are noted, and discussed.