bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of prolactin and thyroxine on tail resorption in R. pipiens: In vivo and in vitro
Authors: Derby A.
Published: June 2005

Thyroxine induces tail resorption in anurans both in vivo and in vitro. This event is accompanied by an increase in the activity of the hydrolytic enzymes acid phosphatase and B‐N‐acetylglucosaminidase. Prolactin treatment promotes tail growth and directly antagonizes the action of thyroxine on tail tissues. This is evident at the gross morphological level as well as at the biochemical level where prolactin inhibits the increase in activity on the hydrolytic enzymes that occurs during thyroid hormone induced resorption.
Pattern formation in the imaginal wing disc of Drosophila melanogaster: Fate map, regeneration and duplication
Authors: Bryant Peter J.
Published: June 2005

Fragments of the wing disc of Drosophila (fig. 2) were either injected into mature third instar larvae for immediate metamorphosis, or cultured in adult abdomens for seven days before being transferred to larvae for metamorphosis. The structures differentiated during metamorphosis were then analysed. The results of the first series of experiments were used to construct an accurate fate map of the disc, and those of the second series were used to determine the regenerative properties of the disc.

The fate map (fig. 7) shows presumptive proximal parts (notum, pleura, and dorsal and ventral hinge) at the two ends of the disc, with presumptive distal wing parts in between. During metamorphosis the disc epithelium folds upon itself along the presumptive wing border, bringing dorsal and ventral wing and hinge surfaces into apposition. The wing surfaces occupy a much smaller relative area, and the hinge parts a much larger relative area, in the fate map than in the adult structure.

The cultured fragments, in general, behaved in accordance with the rule that when two cut surfaces are created by cutting across the disc, regeneration occurs from one of the cut surfaces and duplication occurs from the other (fig. 14). It was possible to define a level in the longitudinal axis of the disc from which regeneration proceeds outwards. Cut surfaces facing away from this level show regeneration, while cut surfaces facing this level undergo duplication. Similar behavior was found for the transverse axis, and for two diagonal series of cuts.

Some fragments with two cut edges could regenerate from one edge while duplicating from the other, whereas others could regenerate from two cut edges simultaneously. However, fragments with four cut edges showed incomplete regeneration, and a high tendency to duplicate even though regeneration in all directions might have been expected on the basis of the other experiments.
An organized distribution of acrosomal proteinase in rabbit sperm acrosomes
Authors: Stambaugh Richard , Smith Monica , Faltas Samiha
Published: June 2005

Acrosomal proteinase was found to be present in a highly organized distribution within the acrosomes of rabbit spermatozoa by cytochemistry. This distribution consists of at least six linear loops of evenly spaced proteinase granules, which run diagonally across the flat side of the sperm head in a criss‐crossing pattern with the two most anterior loops surrounding the region of the acrosome reaction. This is the first description of an organized distribution of enzymes within a lysosome‐like organelle.
Cell patterns and cell movements during early development of an annual fish, Nothobranchius neumanni
Authors: Lesseps R. J. , van Kessel A. H. M. Geurts , Denucé J. M.
Published: June 2005

During epiboly stages the cells (called deep blastomeres) which will form the definitive embryo disperse over the surface of the yolk sphere, only later aggregating and developing an embryonic axis. Five different statistical tests were used to study the pattern formed by the deep blastomeres during epiboly and early dispersed stages. The two most reliable tests, based on the distance from each deep blastomere within a selected area to its nearest neighboring cell, indicate that the distribution pattern changes from regular during epiboly stages to random during dispersed stages 1 and 2. Careful observation and time‐lapse microphotography revealed some aspects of how the cells set up the regular pattern. The deep blastomeres exhibit a variety of cell extensions, with which they often contact one another. When two deep blastomeres make contact during epiboly stages, they soon break the contact and move apart; they overlap one another only rarely. Deep blastomeres are frequently located at, and are even elongated along, borders of the overlying flat cells (enveloping layer cells). These two mechanisms, one similar to contact inhibition of cell movement, the other to contact guidance, may contribute to the rather regular spacing of the deep blastomeres as well as to their arrangement in rows during epiboly stages.
A preliminary investigation into the roles played by the rectal gland and kidneys in the osmoregulation of the striped dogfish Poroderma africanum
Authors: Haywood Geoffrey P.
Published: June 2005

Presented here are the results of a preliminary investigation into ionic and osmotic regulation by the kidneys and rectal gland of the striped dogfish, Poroderma africanum. Fish with ligated rectal glands showed an increase in blood concentration of sodium and chloride within a short time period, reaching a maximum after four days. The blood concentration of the two ions then decreased over the following ten days. Control animals showed relatively unchanged blood‐sodium and chloride levels, over the entire 14‐day period.

After salt loading, both control animals and those with ligated rectal glands showed initial rise in blood sodium and chloride levels, but these returned towards initial values within seven hours of injection. Comparison of the two groups indicates that the rectal gland may control blood‐chloride levels more so than ‐sodium, although its action as a salt regulator does not seem very pronounced in either case. Urine and rectal gland fluid, were collected as a compound fluid, from normal fish, and the estimated cloacal salt loss is discussed. Urine from normal fish was also collected separately and was analysed for its contribution to salt loss. Results are discussed and compared with previous relevant findings.
Adult leg formation during metamorphosis of the silkworm Bombyx mori and its disturbance by exogenous ecdysone
Authors: Hasegawa Kinsaku , Ata Ahmed Mohamed
Published: June 2005

Adult leg formation from pupal legs of simple construction was histologically and histochemically studied using the tibiae of mesothoracic legs of Bombyx mori. The hypodermis detaches from the pupal cuticle one day after pupation and migrates as a whole to the center of the tibia to form a tube‐like adult hypodermis at three days of age. During this process, differentiative cell divisions are observable in full swing one to two days after pupation.

In the mesothoracic leg of fresh pupa, the tibial cavity is divided into two sinuses by a septum. The outer sinus facing the outer side of the leg contains a trachea running straight along the leg. This trachea differentiates into an air‐sac in the tibia of the adult. The tracheal epithelial cells undergo mitoses while moving close to the septum. The epithelium separates from the taenidia and expands in two directions outwardly alongside the septum and towards the hypodermis of the leg, the process of which seems to be achieved by filaments presumably formed by granular cells connecting the epithelium to the basement membrane from one side and to the septum from the other. Retraction of these filaments results in a pulling mechanism which continues gradually until the epithelium is fully stretched and fused with both the basement membrane and the septum to form an air‐sac in the tibia.

Differentiation processes of pupal legs into adult ones such as the mitoses of both hypodermis and tracheal epithelium, the expansion of the epithelium by filaments formed by granular cells, etc., are blocked when exogenous ecdysone is administered in excess in fresh pupae.
The differential effects of estrogen and progesterone on the uterus of the ovariectomized golden hamster
Authors: Rath Narayan C. , Prasad M. R. N.
Published: June 2005

The effects of estrogen and progesterone on incorporation of 3H‐thymidine by the uterus of the ovariectomized hamster are reported.

In the ovariectomized hamster progesterone alone did not induce incorporation of 3H‐thymidine. Estrogen alone caused significant incorporation of 3H‐thymidine, predominantly in the luminal epithelium whereas a prior or subsequent treatment with progesterone activated DNA synthesis in the stroma and muscularis. These results indicate the role of estrogen in priming the uterus of the hamster for the subsequent action of progesterone.
The physiological basis for changes in the freezing tolerance of intertidal molluscs. I. Response to subfreezing temperatures and the influence of salinity and temperature acclimation
Authors: Murphy Dennis J. , Pierce Sidney K.
Published: June 2005

Acclimation to either low temperature or high salinity increased the freezing tolerance of the intertidal mollusc, Modiolus demissus demissus (Dillwyn). Lethal freezing temperatures ranged from −5.11°C to −12.16°C when mussels were acclimated between 12.1o/oo and 33.9o/oo (15°C). Acclimation to 45.5o/oo, however, did not increase freezing tolerance above the value obtained at 33.9o/oo. Lethal freezing temperatures also ranged from −10.4°C to −13.76°C in winter mussels acclimated between 23°C and 0°C (34o/oo). Thermogram recordings of intact M. demissus exposed to various subfreezing temperatures indicated that freezing occurs extracellularly only. Consequently, freezing mortality apparently results from cell dehydration as a critical amount of tissue water is lost as ice. Calorimetry on adductor muscles isolated from M. demissus acclimated to various salinities showed that increasing salinity acclimation increases freezing tolerance by reducing the amount of tissue water frozen and, thus, preventing the attainment of a lethal dehydration level. These calorimetric studies also suggested that the lack of further increases in freezing tolerance above a specific salinity acclimation may result from salt concentrations reaching a toxic level in the frozen tissue. On the other hand, calorimetry showed that the amount of tissue water frozen is independent of temperature acclimation. Thus, low temperature acclimation does not act to increase freezing tolerance by reducing the amount of tissue water frozen but, rather, acts through an unspecified mechanism to increase cellular tolerance to greater levels of dehydration and, possibly, to greater concentrations of toxic salts.
DNA‐RNA bodies in midgut cells of the stick insect, Bacillus rossius
Authors: Scali Valerio , Montanelli Elisa
Published: June 2005

In the anterior part of the midgut and in the Malpighian tubules of the stick insect Bacillus rossius, about 10% of the epithelial cells develop endonuclear bodies which appear as DNA‐RNA masses; in these cells the usual nucleoli are no longer evident. The DNA‐RNA bodies are first formed in third instar larvae, become numerous in the fourth instar and persist in adults. In all larval instars and adults a different kind of DNA‐body has been noticed in the epithelial cells of the posterior midgut. The DNA‐RNA bodies of the anterior midgut and of the Malpighian tubules have been interpreted as the result of somatic gene amplification, whereas the DNA masses of the posterior midgut are likely due to a virus infection.
Fertilization of green frog (Rana clamitans) eggs in their native jelly by bullfrog (Rana catesbeiana) sperm
Authors: Elinson Richard P.
Published: June 2005

Fertilization of R. clamitans eggs in their native jelly occurred when inseminated with high concentrations of R. catesbeiana sperm. Contrary to previous evidence, the block to cross‐fertilization of the R. clamitans × R. catesbeiana hybrids may form in nature.
Are we learning what actually goes on when the brain recognizes and controls?
Authors: Bullock Theodore Holmes
Published: June 2005

Drawing upon recent advances in neuroscience for examples, the thesis is defended that, in contrast to a Kuhnian view of progress by over‐turning whole sciences, progress amounting to revolution in our understanding of nervous systems is happening by the accumulation of many discrete discoveries, and that this process may be expected to continue for a long time.

Twelve propositions are put forward illustrative of ideas developed during and influenced by C. L. Prosser's career, all in the segment of neuroscience concerned with subsystem organization. They range from the generally accepted to the frankly polemical and the merely heuristic.

Ongoing background activity has different forms.

Codes, both spike and graded, are several.

Integrative variables in neuron function are several.

Identifiable cells may be widespread.

Neuronal circuits for behavior are known.

Redundancy is usually overlap.

Reliability can be high.

Recognition neurons may be common and complex.

Command neurons may be common and complex.

Pattern is often central in origin.

Hierarchies and switches may be common.

Subsystem function is an intellectual challenge.

Each of these is briefly elaborated and its logical relation to the others suggested. The role of discrete discovery is thus illustrated — in the generation of new conceptual frameworks that gradually become interrelated and cumulatively change profoundly our picture of what's going on in the brain.
Neural factors and evitability in insect behavior
Authors: Roeder Kenneth D.
Published: June 2005

Compared with more complex behavior patterns involving goal selection, evasive behavior of prey animals elicited by the presence of a natural predator is usually considered to be relatively inevitable and stereotyped. Noctuid moths, while flying in the field at night, show two types of evasive response pattern when their tympanic organs detect the ultrasonic cries of marauding insectivorous bats. Since sound is the sole communication channel between prey and predator, this situation invites neurophysiological and behavioral analysis. When, in the course of studying this behavior, moths are removed by stages from the natural circumstances of this interaction their evasion responses become much less invariant; that is, more evitable. The possible survival value of some evitability in this behavior under natural circumstances is discussed. The afferent nerve response of the noctuid auditory organ is highly stable; therefore, the source or sources of this evitability must lie down‐stream in the moth central nervous system. Acoustic interneuronal systems within the thoracic ganglia and the brain have been examined for lapses in responsiveness and for other indications of transsynaptic instability that might correlate with the demonstrated behavioral evitability.
Photoreceptor processes: Some problems and perspectives
Authors: Goldsmith Timothy H.
Published: June 2005

Visual photoreceptors from both vertebrates and invertebrates are characterized by extensive elaboration of membrane which contains visual pigment (rhodopsin). Visual pigments in all phyla examined are chemically similar: the chromophore is 11‐cis retinaldehyde attached by an aldimine linkage (Schiff base) to a membrane protein, opsin. The effect of light is to isomerize the chromophore to the all‐trans configuration. Beyond these fundamental similarities, several specific areas are discussed in which variations and differences appear.

Light causes vertebrate visual pigments to bleach, liberating the chromophore. Most invertebrate visual pigments do not bleach in the light, but instead form a thermally stable metarhodopsin, with the chromophore in the all‐trans configuration still attached to the opsin.

In the disk membranes of vertebrate rod and cone outer segments, the rhodopsin molecules are oriented with their chromophores nearly coplanar with the disks. Within this plane, however, both rotational and translational diffusion are possible. In the microvillar membranes of arthropod and cephalopod rhabdoms, on the other hand, the situation is less clear. There is evidence for some preferential orientation of chromophores that implies restrictions on Brownian rotation.

In the outer segments of vertebrate receptors, absorption of light by rhodopsin causes the plasma membrane to hyperpolarize due to a decrease in sodium conductance, possibly mediated by calcium ions. In most invertebrate photoreceptors, light causes a depolarization due to an increase in conductance, principally to sodium ions. A subsequent entry of calcium causes a partial repolarization of the membrane, due to a decrease in sodium conductance.

For vertebrate receptors, log threshold is directly proportional to the fraction of rhodopsin bleached (Dowling‐Rushton relationship). The proportionality constant varies in different preparations from less than four to more than 30, and the physical basis for the relationship is unknown. For invertebrates, by contrast, the dependence of sensitivity on rhodopsin concentration is much less dramatic and may well depend simply on the probability of quantum catch.

In most species, vertebrate and invertebrate, the accumulation of photoproduct probably has no effect on membrane conductance, but several possible exceptions exist.

Photoregeneration of rhodopsin from metarhodopsin is likely an important mechanism of recovery in certain arthropods such as diurnal insects, but dark mechanisms of recovery also exist in all phyla. In no single case are they adequately understood.
Phytoenzyme systems as models for an understanding of general metabolic pathways
Authors: Stumpf P. K.
Published: June 2005

A comparison is made between certain aspects of lipid metabolism in plant and animal tissues. While the general biochemical reactions are identical, a number of important variations are described and related to the general metabolic activities of the tissues.
The August Krogh principle: “For many problems there is an animal on which it can be most conveniently studied”
Authors: Krebs Hans A.
Published: June 2005

The idea stated in the title, first clearly expressed by August Krogh, is illustrated by examples from animal biochemistry, physiology, general cell biology, experimental medicine, ethology and botany. General aspects of the concept are discussed.
How do biological systems discriminate among physically similar ions?
Authors: Diamond Jared M.
Published: June 2005

This paper reviews the history of understanding how biological systems can discriminate so strikingly among physically similar ions, especially alkali cations. Appreciation of qualitative regularities (“permitted sequences”) and quantitative regularities (“selectivity isotherms”) in ion selectivity grew first from studies of ion exchangers and glass electrodes, then of biological systems such as enzymes and cell membranes, and most recently of lipid bilayers doped with model pores and carriers. Discrimination of ions depends on both electrostatic and steric forces. “Black‐box” studies on intact biological membranes have in some cases yielded molecular clues to the structure of the actual biological pores and carriers. Major current problems involve the extraction of these molecules: how to do it, what to do when it is achieved, and how (and if) it is relevant to the central problems of membrane function. Further advances are expected soon from studies of rate barriers within membranes, of voltage‐dependent (“excitable”) conducting channels, and of increasingly complex model systems and biological membranes.
The relation of nerves to multiple regeneration in a single newt limb
Authors: Eiland Lonnie C.
Published: June 2005

Three amputation surfaces were formed on the lower arm of a single newt. Growth occurred on all combinations of these surfaces. The proximal surface (the only single surface to form regenerates) produced more regenerates (76% of the cases) than the two more distal surfaces. Blocking the proximal surface with whole skin greatly stimulates the production of accessory structures on the first and/or second more distal surfaces. The mean number of nerve fibers on the proximal surface is considerably higher than the nerve counts of the first more and second most distal surfaces. Limbs possessing a notch or digit(s) on the proximal surface and the absence of growth on the first more and second most distal surfaces also show a decrease in nerve number on the first more and second most distal surfaces. An analysis of the mean number of nerve fibers on the blocked (proximal) surface shows a noticeable decrease in comparison with nerve fibers in an equivalent level on normal limbs. Nerve fiber counts on the first more and second most distal surfaces are markedly increased on those limbs where the proximal surface was blocked with whole skin. Threshold experiments suggest that the irregular occurrence of accessory structures on the first more distal and second most distal surfaces may be related to an insufficient number of nerve fibers on these surfaces. Similarly, a possible explanation for the regular occurrence of accessory structures on the proximal surface is that nerve number on this surface is always above threshold.
Oxygen consumption in the symbiotic hydra Hydra viridis
Authors: Pardy Rosevelt L. , Dieckmann Carole
Published: June 2005

Oxygen consumption was measured in the algal‐bearing and aposymbiotic hydra, Hydra viridis using a microrespirometer. In the light, green animals exhibited a lower rate of oxygen consumption than green animals in the dark or aposymbiotic animals. Treatment of the algal‐bearing animals with the photosynthetic inhibitor DCMU demonstrated that oxygen produced by symbiotic algae as a result of photosynthesis may supply part of the host's respiratory needs.
Dietary tocopherol and sexual reproduction in the rotifers Brachionus calyciflorus and Asplanchna sieboldi
Authors: Gilbert John J. , Litton James R.
Published: June 2005

Brachionus calyciflorus contained no detectable tocopherol (vitamin E) when cultured for long periods on the yeast Rhodutorula glutinis. Using a spectrofluorometric assay and the Asplanchna body‐wall‐outgrowth response bioassay the limits of detection were 6.4 ng and 3.78 pg α‐tocopherol per g dry weight Brachionus, respectively. These tocopherol‐free Brachionus reproduced normally both parthenogenetically and sexually, producing active and potent males and fertilized resting eggs which developed into viable young rotifers. The apparent lack of a tocopherol requirement for male fertility in B. calyciflorus probably also applies to Asplanchna sieboldi and A. brightwelli — rotifers whose male‐producing (mictic) females are induced by dietary tocopherol and whose males therefore are never tocopherol‐deficient. The adaptive significance of the tocopherol requirement for the initiation of sexual reproduction in Asplanchna sieboldi — formerly hypothesized to be the result of a tocopherol requirement for male fertility — is now thought to be related to the role of tocopherol in controlling female polymorphism in this species.
3H‐amino acid uptake and incorporation in sea urchin gastrulae and exogastrulae: An autoradiographic study
Authors: Karp Gerald C. , Weems Marion D.
Published: June 2005

Autoradiographic analysis of gastrulae of the sea urchin, Lytechinus pictus, after brief incubation periods with 3H‐amino acids has indicated that the cells of the ectoderm incorporate significantly greater levels of isotope than the cells of the interior. Further analysis based primarily on incorporation patterns of exogastrulae indicate that the greatly lowered incorporation by the cells of the archenteron reflects the inability of small molecular weight precursors to reach the invaginated cells. The maintenance of high levels of 3H‐amino acid incorporation by ectodermal cells of exogastrulae indicates their relative independence with respect to macromolecular metabolism from the cells of the archenteron.
Delayed allatectomy and feeding in phormia regina (MEIG.): Effects on follicular development
Authors: Mjeni A. M. , Morrison P. E.
Published: June 2005

A delay in feeding a protein meal to the female blowfly following allatectomy results in inhibition of follicular development in the previtellogenic stage. On the other hand, a protein meal given immediately after the operation permits 55% of the flies to deposit yolk in their oocytes. It is concluded that those flies that do not deposit yolk in their oocytes fail to do so because of the absence of a corpus allatum hormone necessary for the synthesis of vitellogenin.
Biosynthesis of lipovitellin by the crustacean ovary. II. Characterization of and in vitro incorporation of amino acids into the purified subunits
Authors: Lui Chung W. , O'Connor John D.
Published: June 2005

The amino acid composition has been determined for two of the five subunits of the crayfish lipovitellin. In addition the molecular weight of each subunit has also been ascertained. Most importantly it is demonstrated that following in vitro incubation radioactive amino acids are incorporated into each of three purified subunits. These data strongly support the suggestion that the vitellogenic ovary of the crayfish is capable of in situ synthesis of lipovitellin.
Induction of antler growth in a congenitally polled Scottish red deer stag
Authors: Lincoln G. A. , Fletcher T. J.
Published: June 2005

A congenitally polled red deer stag was captured from a Scottish deer forest and kept in an enclosure for observations. The animal had rudimentary antler pedicles but no antlers, and during five years of study no significant antler development occurred. Amputation of the apex of one antler pedicle in May 1974 when the stag was 12 years of age resulted in the growth of a complete antler on the operated side, and this antler was subsequently cleaned and cast in the normal way and a new antler cycle was initiated.

The result illustrates that the primary abnormality in this polled stag lay not in his inability to grow antlers, but in his inability to develop fully formed antler pedicles from which normal antler tissue could differentiate. Traumatizing the rudimentary pedicle had the effect of stimulating growth of antler tissue, and once this was formed the process of cleaning, casting and regrowth occurred spontaneously. The incomplete development of the antler pedicles is considered to be responsible for the absence of antlers in the majority of “hummels” in Scotland, and the etiology of the condition is discussed.
Mitotic activity and nucleic acid precursor incorporation in denervated and innervated limb stumps of axolotl larvae
Authors: Tassava Roy A. , Mescher Anthony L.
Published: June 2005

Mitotic activity and DNA and RNA precursor incorporation were compared in innervated regenerating limbs and in denervated, nonregenerating limbs on days 8 and 9 post‐amputation. Innervated limbs had well‐developed cone stage blastemas which showed high cellular mitotic indices and H3‐thymidine labeling indices of 0.40–0.50 and H3‐uridine labeling indices of 0.50–0.75.

In contrast, denervated limbs showed dedifferentiated cells distally under thickened wound epithelia, but essentially no mitotic activity and no blastema formation. These dedifferentiated cells showed lower levels of H3‐thymidine (0.10 index) and H3‐uridine (0.50) incorporation than regenerating limbs.

Labeling indices of wound epithelia are also compared.
New observations on blood pressure in marine Crustacea
Authors: Belman Bruce W.
Published: June 2005

The pressures that drive blood in the circulatory systems of marine Crustacea are substantially higher than previously supposed. In recordings from the heart of nine species, absolute pressures (mean of systolic and diastolic) range from 6.7 cm‐H2O to 36.0 cm‐H2O. No relationship is apparent between blood pressure in these species and either wet weight or heart rate. It is proposed that the maintenance of high internal pressures may be of functional significance in Crustacea, both in urine formation by ultrafiltration and in molting.
The control of spermatogenesis in the green frog, Rana esculenta
Authors: Rastogi R. K. , Iela L. , Saxena P. K. , Chieffi G.
Published: June 2005

The process of spermatogenesis in Rana esculenta (living in the surroundings of Naples) resurges gradually in the spring months, proceeds actively through the summer and declines gradually in the winter months reaching an almost total “quiescence” for a short length of time. The repeating from year to year with a distinct regularity of spermatogenetic cycle suggests that environmental cues play a role in timing its various phases. Both temperature and photoperiod appear to be potential modifiers of spermatogenetic activity in this species. It is, however, probable that photoperiod acts only in a permissive way to facilitate the temperature response which seems to be the more direct modifier of the testicular activity.

The proliferation of primary spermatogonia seems to be favoured by only low temperatures. The formation of secondary spermatogonia, and primary and secondary spermatocytes occurs when there occurs a gradual increase in the ambient temperature, day length and gonadotropin secretion. This period is characterized by very low plasma level of testosterone, that, through the reduced negative feedback to the hypothalamus, favours an increased secretion of FSH‐like gonadotropin. Spermatid formation is entirely androgen‐dependent as confirmed by the use of a specific antiandrogen, cyproterone acetate. In fact spermatid formation naturally occurs in a period when plasma level of testosterone is increasing and pituitary gonadotrops are declining in their secretory activity. In this period the ambient temperature and the photoperiod gradually decline.

The importance of lateral eyes and the pineal gland in the mediation of influence of photic cues has been shown. It seems that without either the eyes or the pineal gland both light and temperature are completely ineffective in stimulating the early spermatogenesis, which shows the permissive role of light on temperature influence upon spermatogenesis.

Hypophysectomy impairs spermatogenesis, which can be restored by a replacement therapy with homoplastic pituitary extract. Testosterone alone does not restore spermatogenesis except enhancing spermatid formation. Pituitary extract stimulates mitotic activity of spermatogonia and formation of primary and secondary spermatocytes. Testosterone is not involved because the stimulatory effects of pituitary extract are only marginally blocked by the antiandrogen. In fact spermatogonial multiplication is partially inhibited, while spermatid formation is totally blocked, indicating that ICSH‐like gonadotropin acts upon the formation of spermatids through the stimulation of testosterone production.

Thus it has been found that there exists a complex interaction between the environmental factors and the “endogenous hormonal trigger” that subsequently steps into the regulation of spermatogenesis.
Stages of tail regeneration in the adult newt, Notophthalmus viridescens
Authors: Iten Laurie E. , Bryant Susan V.
Published: June 2005

Five distinguishable stages of tail regeneration in the adult newt have been established. The stages are based on external morphological changes and internal histological characteristics rather than chronological age of the regenerate.
Gustatory hairs on the mosquito, Culiseta inornata
Authors: Pappas Larry G. , Larsen Joseph R.
Published: June 2005

Gustatory hairs were investigated on the legs and mouthparts of Culiseta inornata (Williston) (Diptera: Culicidae). One type of hair, each innervated by four neurons, was found on the legs. Two of the neurons responded to NaCl stimulation, one neuron to water stimulation, and one neuron to sucrose stimulation. Three kinds of hairs designated Type 1 (T1), Type 2 (T2) and Type 3 (T3) were analyzed on the labella. The T1 hairs are innervated by one sugar neuron, one mechanoreceptor, two salt neurons and one water neuron. The T2 hairs are innervated by two salt neurons and one mechanoreceptor. The T3 hairs, located on the oral surface of the labella, are innervated by a variable number (2‐5) of neurons. Precise identification of the T3 chemosensory neurons was not made because of the small size and inaccessibility of the T3 hairs. Chemosensory hairs on the tip of the labrum were tested electrophysiologically. The sequence of decreasing effectiveness for the three salts tested was KCl > NaCl > LiCl. Labral chemoreceptors also responded positively to sucrose.
Regional differences between nuclear concentration of (3H) estradiol and (3H) progesterone and their action on the uterus of rat during delayed implantation
Authors: Prasad M. R. N. , Sar M. , Stumpf W. E.
Published: June 2005

The cellular and subcellular localization of radioactivity by drymount autoradiography was studied at 5, 15 and 30 minutes after intraluminal or at 5, 15 and 60 minutes after subcutaneous administration of (3H) estradiol or (3H) progesterone to rats in which implantation was delayed by ovariectomy on day 3 post‐coitum, followed by treatment with progesterone. After intraluminal instillation of (3H) estradiol or (3H) progesterone, radioactivity was cleared from the uterine lumen at 5 minutes. After intraluminal as well as subcutaneous injection of (3H) estradiol, radioactivity was concentrated at all time intervals in the nuclei of cells of the substantia propria, glands and muscularis, but not in the luminal epithelium. White blood cells and endothelial cells were unlabeled, while perivascular cells showed concentration of radioactivity.

After intraluminal instillation of (3H) progesterone, radioactivity was retained in the cytoplasm of the luminal epithelium at 5 and 15 minutes, while no such concentration appeared after subcutaneous injection. No selective nuclear retention was observed in the luminal epithelium, in contrast to the substantia propria and muscularis.

The autoradiographic results indicate that progesterone treatment simulating the conditions of early pregnancy, changes the uptake affinity of uterine tissues for (3H) estradiol. The lack of a detectable concentration of estrogen within nuclei of the luminal epithelium does not preclude hormone action. Possible mechanisms of metabolic activation of the uterine luminal epithelium in the apparent absence of concentration of (3H) estradiol to nuclei of the luminal epithelium are discussed.
Effects of seasonal and social factors on testicular activity and hormone levels in domestic pigeons
Authors: Haase E. , Paulke E. , Sharp P. J.
Published: June 2005

Testicular morphology and plasma concentrations of luteinizing hormone (LH), testosterone, progesterone, and estradiol‐17βT were compared in paired (n = 8) and unpaired (n = 7) racing pigeons killed in December. The birds were housed mixed together under natural lighting conditions in two unheated lofts which contained no nesting facilities, in Kiel (54°N), Germany. The paired birds had been paired for at least two months. Testicular weights and diameters of tubules were significantly higher (p < 0.05) in paired (1.64 ± 0.25 gm; 218 ± 12 μm) than in unpaired birds (0.79 ± 0.25 gm; 165 ± 20 μm). The testes of paired birds were spermatogenetically more active than those of unpaired birds. Plasma concentrations of some hormones concerned with reproduction were, in paired and unpaired birds respectively: LH, 2.28 ± 0.43 ng/ml and 0.98 ± 0.36 ng/ml (significantly different, p < 0.1); testosterone, 1.24 ± 0.51 ng/ml and 0.59 ± 0.12 ng/ml (not significantly different); progesterone, 0.58 ± 0.08 ng/ml and 0.90 ± 0.12 ng/ml (significantly different, p < 0.05); and estradiol‐17βT, 16.3 ± 0.95 pg/ml and 18.7 ± 2.25 pg/ml (not significantly different). Thus, the stimulatory effects of a mate on gonadotropin secretion and gonadal activity which have often been reported for female ring doves and domestic pigeons are also demonstrable in males during the late fall. Seasonal testicular regression in the unpaired males at this time of year was not prevented by the presence of paired females.
How X‐rays inhibit amphibian limb regeneration
Authors: Maden M. , Wallace H.
Published: June 2005

The effects of an inhibiting dose of 2,000 rad of X‐rays on the regenerating limbs of axolotl larvae have been examined in a histological and cytological study. Particular attention was paid to the mitotic indices of normal and irradiated epidermal and blastemal cells. Both the characteristic pattern of epidermal mitotic stimulation which normally follows amputation and the later increase in blastemal mitoses are suppressed by irradiation. In most cells the effects are permanent, but in a small proportion a mitotic delay is induced and upon subsequent division chromosome damage in the form of micronuclei is revealed. Thus irradiated cells which do divide almost certainly die. These results are discussed in relation to other theories of X‐ray inhibition of regeneration with particular reference to the view that irradiated cells can be reactivated.
The development of regional pigmentation patterns in black and tan (at) Mice
Authors: Poole Timothy W. , Silvers Willys K.
Published: June 2005

Mice which express the black and tan (at) allele at the agouti locus have black dorsal and yellow ventral hairs. To determine the site of action of this allele, the kind of hair pigment produced by various dermal‐epidermal recombinations of dorsal and ventral black and tan (at / at), ventral nonagouti (at / at) and ventral yellow (Ay / a) embryonic skin has been investigated. The results indicate that it is the dermis which is responsible for the development of regional pigmentation patterns in black and tan mice.
Sperm proteinase release during fertilization of rabbit ova
Authors: Stambaugh Richard , Smith Monica
Published: June 2005

Proteinase activity was found to be present along the sides of sperm penetration tunnels through the zonae pellucidae of rabbit ova using silver‐proteinate staining techniques. This is the first direct confirmation of the generally accepted concept of sperm penetration by proteinase release and digestion of the zona pellucida.
Na is essential for activation of the inseminated sea urchin egg
Authors: Chambers Edward L.
Published: June 2005

The presence of at least 2.5 mM Na during the first several min after insemination is requied for the activation of sea urchin eggs. Of those chemical species examined that exist entirely as cations, and which did not activate the unfertilized egg, only Li substitutes for Na. Ammonium and other amines, with pKa values between 9 and 10.8, in the complete absence of Na (a) can induce nuclear activation of unfertilized eggs, and (b) permit the development of the early fertilized egg through the stage that normally requires Na.
Effects of epididymal occlusion on sperm maturation in the hamster
Authors: Cummins J. M.
Published: June 2005

Hamster epididymal spermatozoa were isolated in the caput, corpus and cauda regions for one, two and three days. Sperm suspensions from these regions were assessed for morphology, motility, viability; and for fertility by A.I. The ability to capacitate was tested by checking for acrosome reactions when the sperm were cultured under defined capacitating conditions at 37°C in vitro.

Normal, mature cauda sperm were highly fertile (overall 77% of ova fertilized) and showed 50–80% incidence of acrosome reactions after six hours in culture. Isolation for up to three days had no effect.

Immature sperm from the caput and corpus were poorly motile, infertile, and did not manifest an acrosome reaction. Isolation for one and two days produced improvements in motility, and distal migration of the cytoplasmic droplet akin to normal maturation, however the sperm remained infertile and did not capacitate in vitro. Survival after three days isolation was poor.

Thus the development of fertilizing ability in hamster epididymal spermatozoa is closely related to the ability to manifest an acrosome reaction in vitro; however it is only poorly correlated with motility and morphology. Completion of sperm maturation in this species appears to require the environment of the cauda epididymidis.
Changes in the shape of the developing vertebrate nervous system analyzed experimentally, mathematically and by computer simulation
Authors: Jacobson Antone G. , Gordon Richard
Published: June 2005

Two forces are necessary and sufficient to produce the transformation of the newt neural plate from a hemispheric sheet of cells one cell thick to a keyhole shape. These forces are: (1) a regionally programmed shrinkage of the surface of the neural plate (accomplished by contraction of the apical surfaces of the neural plate cells and elongation of these cells perpendicular to the plate); and (2) displacement of the whole sheet caused by elongation of either the notochord or the overlying neural plate cells in the antero‐posterior direction. A computer simulation and mathematical analysis (“morphodynamics”), together with experiments and observations on embryos, were used to deduce the morphogenesis of the neural plate from these forces.
Release of DNA template restrictions in rabbit spermatozoa and rat liver nuclei
Authors: Zirkin Barry R. , Boison Adele , Heston W. D. W. , Coffey Donald S.
Published: June 2005

The effects of disulfide reduction on DNA template activity of rabbit sperm and rat liver nuclei are compared. After treatment of rabbit spermatozoa with 5 mM dithiothreitol and 1% Triton X‐100 for 90 minutes at room temperature, sperm nuclei decondense and nuclear template restrictions for DNA synthesis are released. By contrast, similar thiol treatment of isolated rat liver nuclei fails to release DNA template restrictions. These results suggest a significant difference in the control of template activity in mammalian sperm and somatic cell nuclei.
Correlation of enzymatic activity, muscle myoglobin concentration and lung morphology with activity metabolism in snakes
Authors: Ruben John A.
Published: June 2005

In vitro activity of the anaerobic enzymes phosphofructokinase and lactic dehydrogenase from axial muscle tissue of Coluber constrictor, Crotalus viridis and Lichanura roseofusca was shown to correlate with levels of lactate production during activity by these snakes. Additionally, gross and histological lung structure and axial muscle myoglobin concentration were investigated in these species. Coluber was shown to have the most complex lung structure and highest muscle myoglobin content. These are interpreted to be correlated with high aerobic scope in Coluber. Finally, the ophidian saccular lung is postulated to assist in maintanance of high tidal volume.
The regeneration of brachial nerves of contralateral origin into denervated fused newt forelimbs
Authors: Goshgarian Harry G.
Published: June 2005

Previous studies involving the end‐to‐end fusion of the forelimbs of the adult newt have demonstrated that new limbs can regenerate from the transected ends of proximo‐distally reversed limb segments. The limb regeneration could only have been initiated by nerve fibers of contralateral origin. The purpose of the present study is to describe histologically the manner in which nerve fibers of contralateral origin regenerate through the junction of fused limbs into the opposite limb. The first sign of nerve regeneration into the opposite limb was observed at eight days post fusion. The nerves crossed over into the opposite, originally denervated limb in a highly dispersed manner. These nerve fibers eventually aggregated, however, either under the skin or within persisting nerve trunks. By 19 days post fusion the nerve fibers had reached the elbow region of the originally denervated limb and by 25 days they were seen at the most proximal extent of the limb. The diameters of the axons seemed smaller than the diameters of regenerating axons observed in non‐fused newt forelimbs.
Activation of the dormant podocyst of Chrysaora quinquecirrha (schyphozoa) by removal of the cyst covering
Authors: Black R. E. , Enright Rosemary T. , Sung Lan‐Ping
Published: June 2005

Scyphistomae of the jellyfish, Chrysaora quinquecirrha, produce encysted basal buds called podocysts. Podocysts remain dormant for periods of 0 to 25 months at 25 ° C and 15 o/oo salinity. If the cyst coat is punctured it is repaired and 92% of cysts remain dormant, while about 3% excyst and form polyps in a few days and about 5% are nonviable. If the cyst coat is removed entirely, it is always replaced by a new thinner one. Sixty to 75% of the viable cysts then excyst and form polyps, while 25 to 40% remain dormant within the new covering. Removal of the new coat from these results in unusually rapid formation of polyps. The cytological events to excystment are described. Incorporation of radioactive phenylalanine into cellular protein is greatly stimulated by removal of the cyst covering. Free amino acids in the podocyst are at much lower levels than in polyp tissue.
The reacquisition of cell adhesiveness following tissue disaggregation by eleven different agents
Authors: Wiseman Lawrence L. , Hammond William R.
Published: June 2005

Disaggregation of seven‐day embryonic chick neural retina tissue by eleven different agents produces cells which require variable periods of time to become aggregation competent in culture. The time required between cell isolation and the beginning of inter‐cellular adhesion in rotation culture is dependent upon the particular isolating agent used and ranges from zero to sixty minutes.
Induction of meiosis by injection of heterologous protein kinase and phosphorylase kinase in Xenopus laevis oocytes
Authors: Moreau Marc , Guerrier Pierre , Doree Marcel
Published: June 2005

Meiosis reinitiation has been triggered by injection of beef heart protein kinase or rabbit phosphorylase kinase into Xenopus laevis oocytes. Successful injections are followed by germinal vesicle breakdown, chromosome condensation, formation of a normal meiotic spindle, and appearance of an amplifiable maturation promoting factor. Meiosis reinitiation does not occur when the enzymes are introduced into the oocytes simultaneously with EGTA or after pretreatment with cycloheximide. Antipain, an antiprotease which abolishes the response of oocytes to progesterone, does not suppress the meiosis reinitiation induced by injection of protein kinase or phosphorylase kinase.
Electrophoretic introduction of calcium ions into the cortex of Xenopus laevis oocytes triggers meiosis reinitiation
Authors: Moreau Marc , Doree Marcel , Guerrier Pierre
Published: June 2005

Meiosis reinitiation has been triggered via electrophoretic driving of Ca++ into the cortex of Xenopus laevis oocytes freed from functional follicle cells by collagenase treatment. Mg++ could not be substituted for Ca++. Ca++ induced maturation resembles progester‐one induced maturation in so far both are inhibited by cycloheximide, give rise to amplifiable MPF in the cytoplasm of treated oocytes and allow chromosome condensation and the formation of a normal meiotic spindle.
Vaginal opening and early estrous cycles in rats raised at a low ambient temperature
Authors: Nazian S. J. , Piacsek B. E.
Published: June 2005

Rats raised from day 2 of life at an ambient temperature of 10° showed delayed vaginal opening when compared to controls raised at 22°. Coldraised animals were also lighter in weight at the time of vaginal opening and had significantly longer estrous cycles. Low temperature may cause these effects either by suppressing prolactin secretion or, more probably, by elevating thyroid hormone levels which in turn suppress serum gonadotropin concentrations.
28 s and 18 s ribonucleic acid from mammalian spermatozoa
Authors: Betlach Charles J. , Erickson Robert P.
Published: June 2005

The majority of RNA in spermatozoa from the epididymis and ductus deferens of mice was found to be 28 s and 18 s RNA. This RNA was also seen in human ejaculated spermatozoa. Our evidence indicates that little or none of the 28 s and 18 s RNA is transcribed in the maturing mouse spermatozoa and that the majority is synthesized in the primary spermatocyte. This RNA may be necessary to maintain post‐meiotic translation during spermatogenesis.