bluuebunny/crossref_metadata_2025 huggingface dataset:
Iodine induction of metamorphosis in Aurelia
Authors: Spangenberg Dorothy Breslin
Published: June 2005

Extensive laboratory investigations revealed two factors of primary importance for the initiation of metamorphosis (strobilation) in Aurelia aurita. It was found that sufficient quantities of iodide ions (in the form of either potassium iodide or elemental iodine) must be present for scyphistomae preconditioned at a low temperature to strobilate. The iodide ion requirement represents a very low dosage (1: 108 dilution). Thyroxin, also in very minute quantities, likewise induces strobilation in temperature‐preconditioned Aurelia. This response to thyroxin represents the first clearcut demonstration of a morphogenetic response of a coelenterate to a hormone which is biologically significant in vertebrates.

A recommended temperature for preconditioning this Texas strain of Aurelia to strobilate is 19° for at least one month prior to testing. Organisms maintained at 27°C can be induced to strobilate for several months, but they ultimately lose their ability to respond to induction stimuli. A higher test temperature of 27°C does, however, hasten the strobilation of scyphistomae in iodine‐containing media.

Other environmental factors i.e., nutrition, and pH and hypotonicity of the medium, were found to be of little importance (within limits) to the mechanisms involved in the induction of strobilation (SI) in these organisms.
Polyspermic fertilization in pigs during the luteal phase of the estrous cycle
Authors: Hunter R. H. F.
Published: June 2005

Mammalian eggs ovulated during the luteal phase of the estrous cycle or after progesterone injections rarely become fertilized, but the reasons for this low incidence of fertilization are not clear. Mature gilts were injected subcutaneously with 1,500 i.u. pregnant mare's serum gonadotrophin on Day 5 (second day of estrus designated as Day 1), followed by 500 i.u. human chorionic gonadotrophin intramuscularly on Day 9; ovulation occurred 40 to 42 hours later. Eggs recovered from the oviducts of slaughtered animals at specific intervals after ovulation were fixed, stained, and examined by phase‐contrast microscopy.

None of the injected animals showed estrous symptoms. Of 165 eggs examined on Days 11 or 12 from 14 noninseminated animals, 160 (96.9%) were secondary oocytes and five (3.1%) were primary oocytes. Eggs penetrated by spermatozoa were recovered from 14 of 26 animals inseminated 4 to 18 hours before ovulation with 120 ml of fresh, undiluted semen; spermatozoa were recovered from the oviducts of a further three animals. Fifty‐one (31.9%) of 160 penetrated eggs from these 14 animals were normally fertilized, three eggs (1.9%) were fragmenting, nine (5.6%) were primary oocytes, and 97 (60.6%) were polyspermic. The polyspermic eggs contained varying numbers of accessory male pronuclei (2‐7) as well as from 2 to > 50 swollen and unswollen sperm heads. The high incidence of polyspermic eggs found during the luteal phase was considered to be due to an effect of the oviducal environment under the influence of ovarian progesterone on the mechanism controlling the block to polyspermy.
The role of cell migration in the development of the embryonic chick limb bud
Authors: Searls Robert L.
Published: June 2005

Experiments were done to determine if cell migration is involved in cartilage differentiation in the embryonic chick limb bud. Blocks of tissue labeled with tritiated thymidine or with S‐35 sulfate were isolated surgically from early stage 22 limb buds or from the chondrogenic areas of stage 23 or stage 24 limb buds and implanted in unlabeled limb buds of embryos growing in ovo. The host embryos were allowed to develop, the limbs containing the labeled implants were fixed, and the effect of the development of the host on the implanted tissue and the effect of the implant on the development of the host was examined by autoradiography. The implanted blocks appeared to be integrated into the host limbs and to develop harmoniously with the host tissue. No evidence was obtained for any of the following events: (1) movement of cells out of the implanted block of tissue, (2) movement of host cells through the implanted block, or (3) interference by the implanted block with the normal development of the host. It is concluded that cell migration is not involved in the differentiation of cartilage in the embryonic chick limb bud.
Skin grafting in the bisexual teiid lizard Cnemidophorus sexlineatus and in the unisexual C. tesselatus
Authors: Maslin T. Paul
Published: June 2005

Satisfactory procedures for skin transplants have been worked out in Cnemidophorus using C. s. viridis as a pilot species. The homograft reaction occurs in this form, the first clear signs of rejection appearing on about the twelfth day after surgery. Homografts, however, are not rejected in transplants between individuals of the same populations of C. tesselatus; but skin from two of three populations in eastern Colorado are rejected when transplanted to C. tesselatus of north central New Mexico. The reciprocal transplants, in contrast, are accepted by the Colorado forms. This evidence supports the hypothesis that C. tesselatus is parthenogenetic; but it is suggested that the disparity in the behavior of the grafts between the two Colorado populations and the New Mexico population is correlated with the triploid condition of the former and the diploid condition of the latter.
Action of hormones on germinal vesicle breakdown in frog (Rana pipiens) oocytes
Authors: Schuetz Allen W.
Published: June 2005

The mechanism of pituitary gland and progesterone induced germinal vesicle breakdown (GVBD) was investigated in isolated ovarian follicles or oocytes of Rana pipiens. The effects of removing follicular tissue and the metabolic inhibitors, puromycin and actinomycin D, on oocyte responsiveness to the hormones were of Rana pipiens. The effects of removing follicular tissue and the metabolic inhib of protein synthesis, blocked both pituitary and steroid induced GVBD. Timed inhibition studies indicated that protein synthesis was completed at a time approximately midway between the time of progesterone addition and the initiation of GVBD. Only a short exposure of oocytes (5–15 minutes) to progesterone was sufficient to initiate GVBD. Puromycin did not act by preventing the uptake of steroids by the ovarian follicles; however, it caused irreversible effects to oocytes when present in the incubation medium for more than 4 hours. Removal of the follicular tissue from oocytes did not impair oocyte GVBD following exposure to progesterone; however, pituitary induced GVB was inhibited in approximately 50% of the animals utilized. Addition of actinomycin D (100 μg/15 ml) prevented pituitary, but not steroid induced GVBD when added to the incubation medium at the time of hormone administration. Actinomycin D was increasingly ineffective in preventing GVBD when its addition to oocytes was delayed following exposure to pituitary tissue.

These data suggest that pituitary and steroid induced GVBD are mediated by a common mechanism concerned with protein synthesis. The differential inhibition of pituitary induced GVBD with actinomycin D suggests the presence of a pituritary stimulated intermediary process prior to the initiation of protein synthesis. The ovarian follicular tissue appears to be partially responsible for mediating the action of the pituitary gland.
Relative roles of the pituitary, follicle cells, and progesterone in the induction of oocyte maturation in Rana pipiens
Authors: Masui Yoshio
Published: June 2005

The responses of ovarian oocytes obtained from mature frogs (Rana pipiens) to pituitary hormone were examined after removal of the follicular envelope. When the follicular envelope was removed manually or after treatment with collagenase, the apparently naked oocyte can still respond to pituitary hormone by germinal vesicle breakdown and by polar body formation. However, when the follicular envelope was removed after treatment with EDTA or Ca‐Mg‐free solution, the responsiveness of the oocyte was completely lost. Microscopic examination revealed that removal of the follicular cells was incomplete unless Ca‐Mg‐free solutions or EDTA were used. Complete removal of follicle cells prevents the oocyte from responding to pituitary hormone.

Moreover, the naked oocytes packed together with previously separated follicular envelopes showed maturation responses when treated with pituitary hormone solution in the presence of large amounts of ovarian tissue. Naked oocytes which are unable to respond to pituitary hormone can nevertheless full respond to progesterone to undergo maturation reactions. In fact, germinal vesicle berakdown and polar body formation were brought about within intact ovarian tissue by treatment with progesterone alone. Oocytes responding to progesterone alone always remained within the follicular envelope.

The degree of maturation of the oocytes after progesterone treatment was tested by means of nuclear transplantation. When nuclei obtained from blastula or early gastrula cells were implanted into treated oocytes, still within the follicular envelope, normal cleavage occurred. These results indicate that pituitary gonadotropin acts on the follicle cells to stimulate them to release a hormone that directly acts on the oocyte to induce maturation.
A test of the capacity of chick embryo cells to home after vascular dissemination
Authors: Burdick Morton L.
Published: June 2005

Experiments were carried out to determine whether chick embryonic cells have the capacity to lodge preferentially in their homologous organ after intravascular dissemination in host embryos. Chick embryos incubated for five and one‐fourth days were used as donor and hosts. Donors were labeled with tritiated thymidine and selected organs were dissociated into single cells with trypsin. In separate experiments, labeled cells of mesonephros, limb, or heart ventricle were injected into hosts via a large chorioallantoic vein. The hosts were sacrificed 6 and 24 hours later. In each experiment, autoradiographs were prepared from serial sections of these three organs and the labeled cells in each organ were counted.

The distribution of cells among the three organs was found to be almost identical for the three types of cells and at both time periods. Approximately 65–78% of the cells found in the three organs were in the mesonephros; about 21–31% were in the limbs; and about 1–4% were in the ventricle. Thus the cells failed to show a tendency to home; their distribution was completely independent of their organ source. These results suggest that homing is not a general property of embryonic cells, and their lodging properties offer no support for the hypothesis that embryonic cells of different types have highly type‐specific adhesive preferences.
Stability of chondrocyte differentiation and contribution of muscle to cartilage during limb regeneration in the axolotl (Siredon mexicanum)
Authors: Steen Trygve P.
Published: June 2005

In order to determine whether chondrocytes are stable as to type during limb regeneration and whether any cells from limb muscle become chondrocytes in the regenerate, labeled cartilage and muscle were transplanted into limbs which were then allowed to regenerate. Transplanted cells were identified after redifferentiation in the regenerate by three kinds of label: H3‐thymidine detected by radioautography; triploidy as judged by the presence of three nucleoli per nucleus; or a combination of the two.

The results of this investigation indicate that limb chondrocytes are intrinsically stable with respect to cell type, for grafts of both triploid and H3‐thymidine labeled chondrocytes gave rise to morphologically dedifferentiated blastema cells which almost exclusively differentiated into chondrocytes. The small percentage of labeled noncartilage cells observed could have been the result of metaplasia, although it is more likely that all or most of them arose as spontaneous polyploids or as contaminants of the original grafts. Isotope dilution in H3‐thymidine labeled chondrocytes indicated that they had usually divided at least five times. Hence, the basis for the intrinsic stability of chondrocytes must be heritable.

Chondrocytes from the coracoid, scapula, and visceral arch cartilages also contributed cells to cartilage of limb regenerates, and the available evidence indicates that cells released from these cartilages are similarly stable as to type. These cartilages did not dedifferentiate and participate in limb regeneration to the same extent as did limb cartilage.

Results from transplanted limb muscle, labeled by all three methods used in this study, indicate that certain cells of muscle can become chondrocytes during limb regeneration. The exact cellular origin of these chondrocytes, however, is uncertain, for muscle is a mixture of cell types.
Heart induction in salamanders
Authors: Jacobson Antone G. , Duncan James T.
Published: June 2005

Heart determination is a gradual, cumulative process involving inductive and suppressive interactions between the heart mesoderm and nearby embryonic tissues. Our analysis of heart determination in the California newt, Taricha torosa, includes defect and other in vivo experiments, and explants in epidermal vesicles and into hanging drops.

Explants of presumptive heart mesoderm from neurulae into hanging drops of a completely defined salt solution (Niu‐Twitty solution) produce beating hearts only infrequently. The addition of various other tissues and fractions of tissue homogenates changes the frequency and the rate of differentiation. These two parameters were used to assess the stimulatory and suppressive effects of tissues and tissue fractions on the differentiation of the presumptive heart mesoderm.

At least three different factors are active in eliciting and regulating heart differentiation. A specific heart inductor in anterior endoderm increases the rate and the freqency of heart differentiation. A general stimulatory factor in epidermis and other embryonic tissues increases the frequency, but not the rate, of heart differentiation. An inhibitory agent in cranial fold and neural plate tissues delays or prevents heart differentiation. These three factors operate from intact tissues in the embryo or when explanted in vesicles or hanging drops, and are effectively present in a fraction (from sephadex column chromatography) of homogenates of the appropriate tissues.
Partial characterization of the component from normal eggs which corrects the maternal effect of gene o in the Mexican axolotl (Ambystoma mexicanum)
Authors: Briggs Robert , Justus J. T.
Published: June 2005

Axolotl females homozygous for o produce eggs which cleave normally, but never develop beyond gastrulation. This cessation of development is due to a cytoplasmic deficiency which can be corrected by injecting eggs of o/o females with cytoplasm from normal eggs. When so injected, the recipient eggs develop beyond gastrulation and may attain larval stages. The corrective component of normal cytoplasm has the following characteristics: 1. It remains in the supernatant of normal egg homogenates after two hours of centrifugation at 105 g, but is gradually sedimented thereafter. 2. The corrective activity persists for at least eight days when preparations are stored at O°C. It is abolished on heating for one hour at 50° to 55°, and on incubation with crystalline trypsin. 3. The active material is customarily extracted from egg homogenates in 0.1 M or 0.2 M KCl, with 0.01 M Tris, pH. 7.6. It can be precipitated by 2M to 3M ammonium sulfate and retains its corrective activity. It is also precipitated by distilled water, but is then irreversibly denatured. 4. The corrective component is found mainly within the germinal vesicle of large oocytes; then in the egg cytoplasm or extracts thereof following germinal vesicle breakdown. Comparable extracts of blastulae show a reduced corrective activity. Attempts to extract the active material from older embryos and from organs of adults have so far failed. These results suggest that the corrective material, presumably a product of the normal allele of o, depends upon a protein or proteins for its activity. It is produced during oogenesis and later plays an indispensible role in early organogenesis.
Limb regeneration in Ambystoma larvae during and after treatment with adult pituitary hormones
Authors: Tassava R. A. , Chlapowski F. J. , Thornton C. S.
Published: June 2005

Intact and hypophysectomized larvae of Ambystoma maculatum, A. opacum, A. laterale and A. mexicanum were subjected to the influence of adult newt (Notophthalmus viridescens) pituitary hormones by means either (1) of adenohypophyseal implants to the lower jaw or, (2) daily intraperitoneal injections of ACTH. After a 10–21 day treatment period, the ecotopic newt pituitary was removed or the ACTH injections were terminated. Neither procedure had any consequence for limb regeneration, whether limbs were amputated during, or from two to five days following cessation of, hormone treatment. The positive regenerative response suggests that limb tissues of larval Ambystoma do not respond either directly, or indirectly via the adrenal cortex, to the ectopic adult newt pituitary or to ACTH injection. Implanted adult newt pituitaries were found to cause precocious metamorphosis in A. maculatum, A. opacum, and A. laterale but not in A. mexicanum.
Electroencephalographic studies of survival following hypothermic hypoxia in developing chicks
Authors: Peters Joseph J. , Bright Thomas P. , Vonderahe Alphonse R.
Published: June 2005

In chicks between the day of hatching and ten days after hatching the body temperature was lowered from normal to either 34°C or 24°C. Oxygen was then replaced by nitrogen until breathing ceased and the electroencephalograms of the cerebral lobes were reduced to no difference of potential. When this zero potential had endured for a period four times as long as that which yielded about 50% recovery in one to ten day chicks at normal body temperature, artificial ventilation was applied for a maximum of eight minutes or until the onset of spontaneous breathing. This four fold duration of zero potential was: 12 minutes for newly hatched and one day chicks, six minutes for five day chicks, and four minutes for ten day chicks. A withholding of artificial respiration for these prolonged periods of zero potential resulted in the following percentages of recovery: at normal body temperatures, 0%; at 34°C and 24°C respectively, newly hatched chicks 23% and 90%, one day chicks 10% and 40%, five day chicks 40% and 70%, ten day chicks 80% and 90%. Prior to artificial resuscitation birds had electrocardiograms indicating irregular beats, various degrees of heart block, and cardiac arrest for as long as seven minutes; some of these recovered. The transition of the electroencephalogram from zero potential to normal EEG patterns was characterized by a gradual increase in amplitude of both slow and fast waves in the younger chicks and a kind of steplike recovery in the older birds. During recovery about 50% of the younger chicks showed seizures resembling “petit mal”. After a recovery period of 4 to 24 hours the surviving chicks showed no behavioral abnormalities.
Tissue culture analysis of immunological capacity of snapping turtles
Authors: Sidky Younan A. , Auerbach Robert
Published: June 2005

Spleens obtained from the common snapping turtle, Chelydra serpentina (Linné), have been analyzed for immunological competence in several in vitro systems. Spleen fragments can be maintained in tissue culture for several weeks under conditions permitting antibody formation. Such fragments can produce specific agglutinins to sheep or mouse red blood cells when presented with these antigens in vitro. Cells obtained from adult turtle spleens can elicit splenomegaly or hepatomegaly in vitro in a manner suggestive of a graft‐versus‐host reaction. Using these in vitro procedures, it has been observed that maturation of the immunological system of the turtle occurs several months after hatching, and that hibernating turtles are defective in immunological capacity. Histological studies indicate that the snapping turtle has cloaca‐associated lymphoid tissues similar to the bursa of Fabricius.
Inheritance of frog lactate dehydrogenase patterns and the persistence of maternal isozymes during development
Authors: Wright David A. , Moyer Frank H.
Published: June 2005

A female Rana pipiens sphenocephala suspected of being heterozygous at a locus specifying the B or most negatively charged, subunit of the lactate dehydrogenase isozymes was back‐crossed to a R. p. sphenocephala male and outcrossed to a R. p. pipiens male. The results of these crosses show that: (1) the structure of the B subunit of frog LDH is controlled by at least three allelic genes (LDBa, LDBb, and LDBc; (2) LDH of the offsprings' phenotype appears before hatching; (3) maternal‐type enzyme, probably synthesized during oogenesis, persists until at least the eleventh day after the tadpoles begin to feed.
On the role of metal cations in cellular adhesion: Cation specificity
Authors: Armstrong Peter B. , Jones Daniel P.
Published: June 2005

Of the four common alkaline earth cations, only Ca++ is able to protect Rana pipiens embryos from dissociation of the epidermis into isolated cells by EDTA. Presumably this is because only Ca++ is able to satisfy the divalent cation requirement for cellular adhesion in this tissue. Although early stage embryos are completely dissociable by EDTA, the axial musculature, brain and spinal cord become resistant to dissociation by stage 17. Tetraphenyl boron is also effective in disaggregating amphibian embryo tissues.
Induction of conjugation by chemical agents in Paramecium
Authors: Miyake Akio
Published: June 2005

Induction of conjugation by chemical agents was studied in nine species of Paramecium. KCl + acriflavine + Ca‐poor conditions were effective in inducing conjugation in P. caudatum, P. multimicronucleatum, P. aurelia, P. jenningsi and probably in P. trichium. KCL + Ca‐poor conditions were effective in P. caudatum, P. traunsteineri and probably in P. trichium. KCl + acriflavine + Ca‐poor conditions were also effective in inducing interspecific conjugation. Interaction between complementary mating types is not involved in the chemical induction of conjugation, but otherwise chemically‐induced conjugation is, in at least some pairs, essentially identical to normal conjugation induced by the interaction between complementary mating types. The mechanism of induction of conjugation and applications of chemical induction of conjugation to genetic studies are discussed.
The effect of experimental cryptorchism on the isozymes of lactate dehydrogenase in mouse testes
Authors: Goldberg Erwin , Hawtrey Christopher
Published: June 2005

Unilateral cryptorchism produced by experimental retention of one testis in the abdomen of the mouse results in a rapid decrease in the weight of that testis. At the same time the specific activity of lactate dehydrogenase (LDH) decreases to 70% of the normal value. The sperm‐specific isozyme, LDH‐X, declines from 41% of the total activity to only 16% after eleven days in the abdomen. All LDH‐X activity is lost by post‐operative day 24. The relative proportion of the other isozymes of LDH increase following the operation. LDH‐5, absent from the mature testis, is detectable in the cryptorchid testis at post‐operative day 28 and represents 15% of the total LDH activity. These observations provide further support of the suggestion that LDH‐X is only found in the testes when meiosis is occurring.
Synthesis of RNA and protein in relation to oral regeneration in the ciliate Stentor coeruleus
Authors: Burchill Brower R.
Published: June 2005

The effects of actinomycin D, puromycin, and cycloheximide on oral regeneration and macromolecular syntheses in the ciliate Stentor coeruleus were investigated. At concentrations which significantly reduced the rate of RNA synthesis (actinomycin D) and protein synthesis (puromycin and cycloheximide), these inhibitors prevented the completion of development of most cells treated prior to stage “late 4” of regeneration. Cells exposed to the inhibitors in stages “late 4” or 5 were, for the most part, delayed or not affected. Cells treated after stage 5 were unaffected. The oral primordia of many cells arrested in stages “2–3” through 4 were subsequently resorbed, whereas cells blocked in stage 5 retained their oral organelles for the period of the block. The results suggest that both RNA and protein syntheses are essential to regeneration and that the final synthesis of essential macromolecules occurs during stage 5.
Growth and development of chick embryo explants on various protein substrates
Authors: Klein N. W.
Published: June 2005

Chick embryo explants of 11 to 13 somites were cultured on various sources of protein in an attempt to determine if these proteins could relace the proteins of egg yolk as a nutrient substrate for the developing embryo. Various approaches were employed to provide a favorable low molecular weight supplement to the non‐yolk sources of protein. After 48 hours of cultivation, the protein nitrogen and DNA contents of the embryo and the extraembryonic membrane were determined and the stages of morphological development were estimated. The growth and development of embryos cultured on yolk or a mixture of yolk and white were not surpassed with the other sources of protein tested. However, a mixture of horse serum and ovalbumin which first had been equilibrated across a cellophane membrane with an homogenate of whole egg supported levels of embryo growth and development which closely approximated that achieved with yolk and white. Individually, serum supported the growth and development of the extraembryonic membrane while ovalbumin supported the embryo proper. The response of embryo explants to sera derived from laying hens, roosters, or rabbits was similar to that observed with horse serum. The growth of embryos provided with ovalbumin as the sole source of nitrogenous precursors was approximately double that previously achieved with a chemically defined medium containing a mixture of amino acids. Limited growth and development of embryo explants was observed with milk, casein, colostrum, and subblastodermic fluid. Bovine serum albumin and chick embryo extract failed to support embryo explants.
Experimental studies on hatching behavior in the chick. I. Thoracic spinal gaps
Authors: Oppenheim Ronald , Narayanan C. H.
Published: June 2005

Using microsurgical techniques spinal “gaps” were made in the thoracic level of chick embryos at two days of incubation by removing small lengths of neural tissue. These same embryos were then examined in detail between 17 days and hatching for any behavioral modifications.

The frequency and patterns of various movements anterior to the gap were found to be similar to control embryos. Leg movements were also found to be equal in number to those of the controls. Operated embryos, while being able to orient correctly in the egg and to pip the shell, were not able to hatch on their own. This was due to an inability of these embryos to coordinate movements of the legs with movements anterior to the spinal gap, and to the absence of vigorous stemming movements of the legs against the shell. This prohibited them from cracking and rotating around the sell and hence from hatching.

Three of the spinal embryos which were artificially hatched (pulled out of shell) were not able to stand or walk after two days. However, the legs of these chicks did show “spontaneous” alternating kicking movements and were responsive to stimulation.
Properties of intact photoreceptor cells lacking synapses
Authors: Eichenbaum Daniel M. , Goldsmith Timothy H.
Published: June 2005

Surgically undamaged photoreceptor cells that have no connections with the central nervous system were obtained by transplanting the eye imaginal disc of third instar housefly larvae (Musca domestica) into the abdomens of host larvae and waiting for development of the host flies. Following differentiation, the photoreceptor cells of the transplants have normal cell bodies and rhabdomeres. Their axons, on the other hand, do not make synapses with higher order cells. The retinular cells, thus isolated from the optic lobe, give electrical responses to illumination that are indistinguishable from the membrane responses of normal receptor cells, and at moderate intensities of stimulation consist of an initial transient and a plateau. This graded depolarization of the soma (receptor potential) spreads electrotonically into the axon without initiating spikes. Neither CO2 nor tetrodotoxin has an effect on the receptor potential of isolated photoreceptors. The transplants dark adapt at the same rate as normal retinulae, dark adaptation being slower following longer periods of light adaptation. Clearly in flies the development of the synapses of the lamina ganglionaris is not necessary for normal physiological development of the receptors, and the responses of the photoreceptors of normal eyes can be generated without significant feedback control from the optic lobe.
The effect of sixty‐cycle AC current on the regeneration axis of Dugesia
Authors: Marsh Gordon
Published: June 2005

Dugesia dorotocephala and D. tigrina were sectioned transversely, imbedded in agar, and exposed to alternating current in a rectangular chamber. At field strengths of from 310 to 418.4 rms mv/mm potential fall, functional bipolar, regressive bipolar and permanent bipolar regenerants were produced. No regenerants showed reversal of polarity. The similarity in field strength for the three groups was primarily due to the extreme motility of imbedded pieces. The results were independent of absolute healing time and duration of exposure to the field, and of body level of regenerate origin. No significant differences were found between the species with respect to mortality or response to the AC field. AC field action is non‐polar, but its direction must coincide with the regenerant axis to be effective. The field operates to reduce the normal antero‐posterior polarity.
Mitotic patterns in the optic tectum of the chick during normal development and after early removal of the optic vesicle
Authors: Cowan W. M. , Martin A. H. , Wenger Eleanor
Published: June 2005

The number of mitotic figures in the optic tectum of the chick increases from just over 20, 000 on the fourth day of incubation (stages 25 and 26) to a peak of approximately 45, 000 on the fifth and sixth days (stages 28 and 29). Thereafter, the number declines sharply to about 10, 000 and 2, 000 on the eighth and ninth days respectively and to as few as 100 and 18 on the eleventh and twelfth days. The dividing cells are not uniformly distributed throughout the tectum but show a clear rostral to caudal gradient such that at every stage the number of mitoses in the caudal half of the tectum exceeds that in its rostral half. In addition the number of mitotic figures in the ventrolateral half of the tectum exceeds that in its dorsomedial half between the fourth and seventh days of incubation, but this pattern is reversed during the last few days of mitotic activity.

The process of cell proliferation in the optic tectum appears to be completely independent of the developing eye since there is no significant change in either the total number of mitotic figures in the tectum, or in their spatial distribution, after complete removal of the optic vesicle towards the end of the second day of incubation.
Effects of testosterone and estrogen on spermatogenesis in Rana hexadactyla Lesson
Authors: Basu S. L.
Published: June 2005

Observations on the normal seasonal spermatogenesis of Rana hexadactyla Lesson reveal that it is continuously cyclic nature. The effect of steroids during different times of a year on the spermatogenesis has also been studied. Testosterone treatment inhibited spermatogenesis at the secondary spermatogonial stage in all the experimental individuals. Estradiol implantation on the other hand caused a general disintegration of the tubular histoarchitecture. The probable significance of the steroid action on the seminiferous tubules and its relation with the hypophysis and the target organ are discussed.
Hormonal influence on salivary glands of chimney swift (Chaetura pelagica) in organ culture
Authors: Barnawell Earl B.
Published: June 2005

Salivary glands from chimney swifts taken at intervals during the reproductive season were maintained in organ culture in a chemically defined medium supplemented with insulin, glucagon, prolactin, corticosterone, testosterone and crude pituitary extract in various combinations. Insulin and corticosterone or glucagon promoted survival of the tissues in vitro and insulin plus corticosterone or glucagon promoted secretory activity. Prolactin, crude pituitary extract or testosterone did not promote secretion. Essenially one hundred percent of the cultured explants survived when incubated at 37°C. However, at 44°C a large proportion of the explants failed to survive except in the presence of insulin plus corticosterone or glucagon. Prolactin did not promote survival at high incubation temperature. Hormones primarily concerned with carbohydrate metabolism appear to play an important role in in vitro survival and secretion. The appearance of secretion in vitro may be owing to the support of secretory processes initiated in vivo prior to the culture period.
Bronchial diverticula in short‐tailed shrews: Pulmonary adaptation to dust contaminated environment
Authors: Parke Wesley W. , Wetzel Ralph M.
Published: June 2005

Examination of the lung and unusual extrapulmonary bronchial diverticula of the short‐tailed shrew (Blarina brevicauda) showed that this mammal aspirates a considerable quantity of foreign material during its constant burrowing. Experimental inhalation of an aerosol of carbon black indicated that the diverticula trapped and expelled some of the particles and may be a pulmonary adaptation to a contaminated environmental atmosphere.
The effect of light and light deprivation upon the ultrastructure of the larval mosquito eye. III. Multivesicular bodies and protein uptake
Authors: White Richard H.
Published: June 2005

The formation of multivesicular and lamellar bodies, organelles characteristic of arthropod photoreceptor cells, is shown in the mosquito eye to be dependent upon light. The organelles are nearly absent from light deprived eyes; they form in large numbers when such eyes are first illuminated. Multivesicular bodies form adjacent to the rhabdomere, then move proximally into the body of the cell, ultimately being transformed into lamellar and probably dense bodies. Experiments in which ferritin was injected into the hemolymph of the head confirmed the hypothesis that the coated vesicles of the rhabdomere are pinocytotic vesicles. Ferritin taken into the cell by rhabdomeric vesicles is sequestered in multivesicular bodies.
Determination of the mesonephric kidney
Authors: Etheridge Albert L.
Published: June 2005

The determination of the mesonephric kidney in Taricha torosa involves both inductive and suppressive interactions between the kidney mesoderm and other embryonic tissues. The analysis of kidney determination was made by explanting the mesonephrogenic mesenchyme in epidermal vesicles either alone or in combination with the endoderm, notochord, neural tube, neural crest, lateral plate mesoderm, somite or nephric duct. It was found that the endoderm, notochord, early somite, and early lateral plate mesoderm are inductors of the mesonephros. Also, both premigratory and migratory neural crest cells, neural tube, older somite, and older lateral plate mesoderm were identified as suppressors of the development of the mesonephros.

Most of the above interactions occur before the nephric duct makes contact with the mesonephrogenic mesenchyme. Too much emphasis has been placed on the nephric duct as being the inductor of the mesonephros. The mesonephric kidney is determined by late tailbud stages; a result of the inductive and suppressive interactions it has experienced.
Fine structural analysis of the conjunctival papillae in the chick embryo: A reassessment of their morphogenesis and developmental significance
Authors: van de Kamp Maarten
Published: June 2005

Development and regression of the conjunctival papillae have been examined with both light and electron microscopy. The fibrous strands which extend from the papillae to the mesenchyme of the pre‐ossicular plate have been identified as collagen. Furthermore, the initial deposition of collagen fibrils has been shown to occur within channels between cells of the basal epithelium during stages 2 and 3. Bundles of collagen fibrils extend continuously from the uppermost portions of the cavity of the papilla to the mesenchyme of the condensing pre‐ossicular plate during stage 5.

Degeneration is localized in a small area of the papilla during stages 3 and 4 but spreads throughout the mass during stage 5. Late in stage 5, necrotic epithelial cells are sloughed into the cavity of the papilla from its basal layer. These findings are discussed in relation to earlier light microscopic and experimental studies which have shown the papillae to be required for the subsequent development of the scleral ossicles in the subjacent mesenchyme.
Natural and immune hemagglutinin forming capacity of immature chickens
Authors: Seto Rank , Henderson W. G.
Published: June 2005

The level of natural hemagglutinins for several mammalian erythrocytes was low in embryos 12 to 20 days of age and in baby chicks up to two weeks of age. The antibody level increased rapidly during the third and fifth week after hatching and at a slower rate thereafter with age. The agglutinin levels were highest for rabbit and rat erythrocytes, intermediate for mouse and hamster cells, and lowest for sheep red cells.

The level of immune antibody in the blood during the primary responses to sheep, mouse and hamster erythrocytes (1) reached a peak about 6 days after antigen injection, (2) was higher when antigen was injected intravenously as compared with the intraperitoneal route, (3) varied with antigen dose and, (4) increased with the age of the bird. Moreover, the antibody forming capacity was drastically reduced by x‐irradiation or cyclophosphamide treatment of embryos or baby chicks.

Employing approximately optimum antigen doses, it was found that 14‐ to 18‐day embryos were unresponsive, whereas some newly hatched chicks and practically all week‐old chicks were capable of producing hemagglutinins to five mammalian erythrocytes. Associated with this change in competence, there is an increase in number of germinal centers in the spleen. The antibody forming potential increased with age, growing most rapidly during the first month and slowly thereafter. The possible relationship between the growth of the primary antibody forming potential and the occurrence of natural antibodies has been discussed.
On the rapid running of ghost crabs (Ocypode ceratophthalma)
Authors: Hafemann Dennis R. , Hubbard J. I.
Published: June 2005

Specimens of the ghost crab, O. ceratophthalma, ran at 1.825 ± 0.09 m/second on the sandy shore of the Flinders Islands and 2.33 ± 0.14 m/second on the deck of the R/V Alpha Helix. Specimens of Pachygrapus transversus ran at 0.92 ± 0.06 m/second on the ship's deck. Sex did not affect speed. O. ceratophthalma is anatomically and functionally specilized for running. The gait of O. ceratophthalma was recorded cinematographically and could be described by the fastest variants of the model devised by Wilson ('66) for insect walking.
The developmental genetics of polymorphism in the rotifer Asplanchna. II. A method for quantitative analysis of changes in morphogenesis induced by vitamin E, and the short‐term inheritance of the effects of vitamin E
Authors: Birky C. W. , Power Judith A.
Published: June 2005

Amictic female Asplanchna sieboldi, reproducing asexually by diploid parthenogenesis, are predominantly saccate in form when fed paramecia. The addition of vitamin E to their diet causes their female offspring to develop regular outgrowths of the body wall, or humps. A continuous spectrum of intermediate forms connects the saccate (S) and fully humped (H) morphotypes. We have shown that this response can be studied quantitatively with the use of an ordinal scale for measuring the degree of hump development: five morphotypes are distinguished and assigned scores (S = 1; I1 = 2; I2 = 3; I3 = 4; H = 5). The response of embryos to exogenous vitamin E, measured with this scale, is proportional to the amount of vitamin E in the diet of their saccate parents. When vitamin E is removed from the diet of humped females, offspring with humps continue to be produced for up to five generations, with a gradual decline in morphotypic score. This short‐term inheritance of an environmentally‐induced trait can be explained by the passive transmission from parent to daughter of a stable endogenous inducer, which may be vitamin E itself. However, the relationship between the magnitude of the response and the concentration of this hypothetical inducer is not a simple one. For example, when females are fed vitamin E for one generation, the mean score of the granddaughters is greater than that of their daughters, which received no additional exogenous vitamin E. The same considerations apply to the inheritance of increased nuclear number in certain organs of A. brightwelli, which is another response to increased levels of dietary vitamin E.
The effects of crowding on larvae of the meal moth, Ephestia kühniella
Authors: Smith Stephen D.
Published: June 2005

Ephestia larvae of strain BII (inbred for 140 generations) were obtained at late first or early second instar, and subjected to progressively more crowded conditions. Population sets of 2, 4, 8, 16, 32, and 64 larvae were confined together. In this experiment crowding caused a diminution of body size, an apparent delay in development, and increased mortality.

Experiments were also performed with sets of 64 larvae in containers with progressively greater surface area. Areas of 12.6 cm,2 and 144 cm 2 were employed. In some cases weight of food remained constant, in others, the depth. These experiments suggested that the crowding effect was not unimodal. Inhibition of body size remained, while the inhibition of development rate and mortality decreased with increased surface area.

A third set of experiments measured the pO2 and pCO2 at weekly intervals in 12.6 cm 2 jars containing 4, 16, 32, and 64 larvae each, and 28.2 cm2 jars containing 64 larvae. A decrease in pO2 was found only at 14 days after isolation in the 32, 64, and 64/28.2 cm 2 jars. When jars of 64 larvae each were flushed continually with air, inhibition was not reduced. Thus the differences in pO2 were judged to be insignificant to the inhibition, and the inhibitor was judged to be non‐volatile.

Mortality in the crowded populations was found to result from failure to complete eclosion by pupae behaviorally “trapped” beneath the cocoons of other larvae.
In vitro acrosome reaction and capacitation of golden hamster spermatozoa by bovine follicular fluid and its fractions
Authors: Yanagimachi R.
Published: June 2005

Unheated bovine follicular fluid is very toxic to hamster spermatozoa. This toxicity is due to the action of globulin or globulin‐like substances in the fluid. When the fluid is pre‐treated at 56°C for about 30 minutes these spermicidal substances are detoxified, and the fluid becomes capable of inducing the acrosome reaction and capacitation of the spermatozoa. Follicular fluid contains two factors responsible for the induction of the acrosome reaction and capacitation of spermatozoa, namely the sperm‐stimulating factor and the acrosome reaction‐inducing factor. An efficient sperm acrosome reaction and capacitation can be accomplished only in the presence of these two factors. The sperm‐stimulating factor is dialyzable and heat‐stable (at 90°C). The acrosome reaction‐inducing factor, on the contrary, is non‐dialyzable and heat‐labile (at 90°C). The relationship between sperm acrosome reaction and capcitation is discussed.
The stabilization of cartilage properties in the cartilage‐forming mesenchyme of the embryonic chick limb
Authors: Searls Robert L. , Janners Martha Y.
Published: June 2005

Experiments have been done to determine the time in the development of the embryonic chick limb when the cells in the cartilage‐forming area become “stabilized.” The particular criterion for stability used in this work was the ability of the cells to resist the influences in the limb which cause some limb mesenchyme cell to form cartilage and other limb mesenchyme cells to form soft tissue. Blocks of cartilage‐forming mesenchyme were transplanted from the cartilage‐forming area of a second limb to the prospective soft tissue area of a second limb. The host limb was permitted to develop for 48 hours, and then examined to determine if the implanted cells had formed cartilage outside of the normal cartilage pattern of the host limb. The embryos used as a source of the implanted blocks varied in stage from stage 22 to stage 27, the hosts also varied in stage from stage 22 to stage 27.

It was found that a block of cartilage‐forming mesenchyme generally would conform with the host limb pattern if the donor was stage 24 or younger and the host was stage 24 or younger. A block of cartilage‐forming mesenchyme generally did not conform with the host limb pattern if the donor was stage 25 or older whatever the stage of the host. We conclude that the cartilage‐forming cells become stabilized by this criterion between stage 24 and stage 25.
Meiosis of mouse eggs before and after sperm penetration
Authors: McGaughey R. W. , Chang M. C.
Published: June 2005

Mature mice were induced to ovulate by injections of PMS and HCG and their eggs were prepared, using an air‐dry technique, for the examination of chromosomes during the first and second meiotic divisions. Sixty percent of 72 eggs recovered from follicles between 10 and 8.5 hours before ovulation were at prophase, whereas 91%–64% of 139 eggs were at metaphase I from 7 to 3 hours before ovulation. Anaphase I and telophase I were seen in 17 eggs 4.5–0 hours before ovulation. The bivalents were clumped together in a single mass at the earliest stage of diakinesis. Separate, extended bivalents which underwent contraction up to metaphase I were observed later. Counts of bivalents in 82 eggs at diakinesis and metaphase I revealed no deviation from the haploid number (n = 20). The dyads in the first polar body were usually extended and somewhat diffuse in appearance, whereas those in the egg were not. A total of 295 eggs were examined from 24 females inseminated 1.5 hours after ovulation. At 3, 3.5, 4.5 and 5.5 hours after ovulation 3%, 20%, 26% and 43% of recovered eggs respectively were penetrated by sperm, indicating that a certain length of time may be required for capacitation of mouse sperm. Approximately 90% of eggs with an intact sperm head (Type I) were at metaphase II and nearly 100% of eggs with a swollen sperm head (Types III and IV) were at telophase II. Four distinct configurations of metaphase II, “spread,” “clumped,” “compact,” and “granular” were seen in 384 unfertilized eggs recovered from 36 females at various times after induced ovulation. The haploid number of dyads was observed in all of 70 eggs counted at metaphase II in the “spread” configuration. The proportion of unfertilized eggs with a “compact” metaphase II increased from 2% at 5–7 hours to 12% at 24–31.5 hours after ovulation, while the proportion of eggs with a “granular” metaphase II increased from 11% to 47% over the same period. The second meiotic metaphase exhibited these degenerative changes mainly at the end of the fertilizable period of the egg.