bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histological observations on the ovary of the white‐tailed mole, Parascaptor leucurus
Authors: Duke Kenneth L. 
Published: February 2005

AbstractThe ovarian histology of Parascaptor leucurus, the white‐tailed mole, is very similar to that of Talpa europeaa, especially with reference to the presence of two zones: (1) an ovigerous, or female, zone, and (2) an interstitial‐cell, or male‐like, zone. The ovigerous zone contains the follicles and corpora lutea. This pole of the ovary only is covered with a germinal epithelium. The interstitial‐cell zone is made up entirely of islands of interstitial cells and of very short testis‐like tubules, the so‐called medullary follicles.Follicular growth appears to follow the conventional mammalian pattern.Sections of the medullary follicles have an appearance very similar to those of seminiferous tubules of late fetal and early postnatal testes in cellular make‐up and relation to the rete tubules.Evidence is presented that suggests the occurrence of delayed implantation in this genus.
Fine structure of tadpole melanophores
Authors: Jande Sohan Singh 
Published: February 2005

AbstractThe fine structure of frog tadpole melanophores has been found to be different from that of teleost chromatophores (Falk and Rhodin, '57). The cytoplasm is not divided into inner and outer regions. Organelles are distributed throughout the cytoplasm. A special search for microtubules was made and only a single such structure could be found.
The relation of age to the incorporation of tritiated thymidine into the thymus of fischer rats
Authors: Berman Irwin , Winter Susan R. , Newby E. J. 
Published: February 2005

AbstractA time study of the incorporation of tritiated thymidine into the thymus of Fischer rats ranging from 15 days to one year of age has been made. The data obtained from both autoradiographic and histological analyses indicate that the mitotic activity in the thymus of young animals is much higher than in old animals. The medium thymocyte, by virtue of its higher relative proliferative capacity, is responsible for the greater portion of cellular production during the intense pre‐pubertal growth phase of the thymus. A decrease in proliferative capacity of medium thymocytes occurs between 60 and 90 days of age, which appears to initiate the onset of age involution of the thymus. The data further indicate that small thymocytes are cells which do not undergo division.
Radioautographic studies of reticular and blast cells in the hemopoietic tissues of the rat
Authors: Caffrey Ruth W. , Everett N. B. , Rieke W. O. 
Published: February 2005

AbstractThe rates of proliferation and developmental capabilities of reticular cells in the hemopoietic tissues of the rat were studied after administering single and multiple injections of tritiated thymidine. Radioautographic analyses were made using both smears and sections of the various hemopoietic tissues. Liquid scintillation counting of tissues was also employed. Sublethal gamma irradiation was administered to animals previously labeled with H3‐thymidine in order to evaluate the role of reticular cells during the repopulation of the marrow.The labeling patterns (per cent label and average grain count) of reticular cells, both phagocytic and non‐phagocytic types, are compared with the labeling patterns of blast cells. It is shown that reticular cells are proliferating at a slow rate and do not demonstrate the labeling patterns expected of stem cells for the rapidly proliferating myeloblasts, pronormoblasts, lymphoblasts and megakaryoblasts. The labeling patterns of cells which are generally believed to precede the committed blast cells, the hemo‐cytoblasts, are also discussed and are contrasted with the labeling patterns of the reticular cells. During recovery from sublethal irradiation there was no evidence of differentiation or transformation of labeled reticular cells into blast cells of the various blood cell lines. The labeling patterns of blast cells suggest that the great majority are derived from members of their own group and that any proposed precursors of these blasts would need to be relatively few in number, rapidly proliferating and highly radiosensitive.
Volumetric compartmentalization of the cranial cerebrospinal fluid system determined radiographically in the cat
Authors: McCarthy Lawrence E. , Borison Herbert L. 
Published: February 2005

AbstractA volume‐distribution analysis of the water soluble contrast medium, meglumine iothalamate, injected into various ventricular and subarachnoid sites was accomplished radiographically in the cat with the aid of a newly designed screw‐type cannula having a deadspace of 6 to 8 m̈l. The cannula is positioned stereotaxically and mounts directly and permanently in the cranium by a single self‐tapping insertion maneuver. As little as 100 m̈l of solution injected into the anterior horn of the lateral ventricle, or 50 and 20 m̈l into the third and fourth ventricles, respectively, was visualized immediately in the lateral apertures of the fourth ventricle connecting with the subarachnoid spaces. Injection of 50 m̈l into the posterior horn of the lateral ventricle delineated the entire ventricle as well as the interventricular foramen. A volume of 12 m̈l deposited in the base of the third ventricle served to define the hypothalamic cleft and infundibular recess. If rate of injection was not excessive, the solution could be introduced into the third and fourth ventricles without penetrating into the more anterior regions. Radiopaque medium injected into subarachnoid spaces (cisternae ambiens and cerebellomedullaris) did not enter the ventricular system.
The number of nerve fibers in the limb of the mouse and its relation to regenerative capacity
Authors: Rzehak Karol , Singer Marcus 
Published: February 2005

AbstractIn regeneration of the salamander limb the nerve must satisfy a quantitative threshold below which regeneration does not occur. The present work explores the reason for the inability of the mammalian limb to regenerate by analyzing the number of nerve fibers available in the wound of the amputated limb. The number expressed per unit area of amputation wound is only 16% of that of the newt, Triturus, a regenerating form. It is known that when the number of fibers in the newt's limb is reduced to about a third or less of the normal number, regrowth does not occur. The results are discussed against the background of published unsuccessful attempts to induce regrowth in the mammal. Finally, the results affirm findings published previously of an evolutionary trend in the vertebrate series of decline in quantity of peripheral innervation which attended elaboration of central nervous mechanisms.
The morphology of circulus arteriosus cerebri in rats
Authors: Brown James Oliver 
Published: February 2005

AbstractLittle has been reported concerning circulus arteriosus cerebri in adult rats. A study of rats' brains perfused with latex and fixed in formalin revealed the general configuration of a circular type pattern of the major cerebral arteries in which all vessels were patent. No major vessel was “string‐like” and no circles were incomplete.Certain morphological features not described previously were observed. Included among the more significant of these were: (1) the asymmetrical origin of the posterior cerebral artery found to occur in more than half of the animals; (2) the presence of cleft‐like buttonhole formations along the anterior cerebral artery of one or both sides, a feature that was practically species characteristic; (3) the occasional presence of an anterior communicating artery supplemental to the commonly occurring side to side fusion of the two anterior cerebral arteries. Two animals, possessing two anterior communicating arteries connecting otherwise unfused anterior cerebral arteries, were exceptional; (4) an olfactory artery to the nasal cavity branched promineantly from the anterior cerebral artery in all animals.Before exiting from the cranial cavity through the dorsomedial cribriform foramen, the olfactory artery gave origin to a laterally directedramus, the central cribriform artery, that passed through the central cribriform foramen into the nasal cavity.
Cell movement, proliferation and death in the formation of the embryonic axis of the rabbit
Authors: Daniel Joseph C. , Olson John D. 
Published: February 2005

AbstractRabbit blastocysts of ages six to eight days, post coitum were used to study the roles of cell proliferation, cell movement and cell death in the formation of the primary embryonic axis.Neutral red staining of local spots on the surface of cultured embryos provided information on the direction and speed of cell movement. Nile blue sulphate was used to detect necrotic cells in the embryonic areas. Mitotic indices were determined from counts made of the cells of serially sectioned embryos.It is concluded that the formation of the embryonic shield and primitive streak from the disc in the rabbit embryo is primarily achieved by migrations of cells that are being rapidly proliferated over the entire surface of the embryonic area. Cell death occurs but is an insignificant factor in this phase of embryonic growth.
Observation on the microcirculatory architecture of the rat liver
Authors: Hase Tatsuo , Brim Jack 
Published: February 2005

AbstractMicrocirculation of rat livers was studied on preparations perfused with silicone rubber. Silicone rubber provided an excellent perfusion medium for the study of the special arrangement of hepatic microcirculation.As demonstrated by Gershbein and Elias ('54), a great portion of the hepatic venous tree of the rat liver receives sinusoidal channels and thus this portion is located centrilobularly.In the portal venous system of the rat liver, not only the distributing veins but also the conducting veins give rise to inlet venules regularly to adjacent peripheral sinusoids.Rich capillary networks of the periductal plexus which receive their afferent channels from the hepatic arteries and empty their blood either into the portion veins or into the adjacent peripheral sinusoids are demonstrated in the portal canals. Less prominent fine capillaries are distributed in the walls of portal veins and in the connective tissue components of larger portal canals. Existence of a more direct type of anastomoses between the hepatic arteries and portal veins through capillary networks in the medium and large sized portal canals is also indicated. Evidence for the existence of intralobular arteriolar terminals were not obtained and the present observation indicated that the hepatic arteries terminate at the periphery of the lobule.
The fine structure of Brunner's glands in the rat
Authors: Leeson C. Roland , Leeson Thomas S. 
Published: February 2005

AbstractThe appearance of Brunner's glands in the rat, before and after feeding, has been examined with the electron microscope. The glands are arranged in the duodenal submucosa in aggregates of coiled tubules which open into the bases of the crypts of Lieberkühn. Component cells appear to be more mucous than serous. The basal cytoplasm contains some granular endoplasmic reticulum, numerous free ribosomes and mitochondria. Multiple Golgi elements lie in relation to the nucleus and the apical cytoplasm contains varying concentrations of pale secretory droplets which show a tendency to fuse into complexes. Scattered between the large secretory droplets are numerous small vesicles, also considered to contain a secretory product.The cytological features are discussed in relation to previous observations on Brunner's glands in other species. It is apparent that there are considerable species differences. However, in all species it appears likely that the complex secretory materials are elaborated principally by the ergastoplasm.
A radioautographic study of the proliferative activity of adrenocortical and hypophyseal cells of the rat at different periods of the estrous cycle
Authors: Hunt Thomas E. , Hunt Eleanor A. 
Published: February 2005

AbstractThe hypophysis and adrenal glands of Long‐Evans female rats about two months old were examined after receiving thymidine‐H3 at different phases of the estrous cycle. Radioautographs showed labeled cells preparing for or in division. In the hypophysis, where labeled cells were uniformly distributed in the anterior lobe, greatest activity was at estrus about 12 to 24 hours after ovulation. An average of about 300 labeled cells per mm2 occurred but some individuals had over 700 per mm2. At other periods of the cycle the average was less than 40 labeled cells per mm2.The greatest proliferative activity in the adrenal cortex was found the first day of diestrus when an average of 92 labeled cells per section occurred compared with fewer than 50 per section at other stages. About 80% of the activity in early diestrus occurred in the outer zona fasciculata where it was four and eight times that at proestrus and estrus respectively. In the glomerulosa the number of labeled cells remained about the same on different days of the cycle and in the reticularis the average number was somewhat greater during diestrus when there were 3.4 labeled cells per section.
A study of the rat thyroid during perinatal days with observations of compensatory changes following unilateral thyroidectomy
Authors: Eguchi Yasunobu , Morikawa Yoshio 
Published: February 2005

AbstractMeasurements of volume of the thyroid, diameter of follicles and height of follicular cells were made under normal or experimental condition of unilateral thyroidectomy in late fetal and newborn rats. During perinatal days, the thyroid did not enlarge, the diameter of follicles was reduced and the height of follicular cells lowered. Unilateral thyroidectomy in fetuses on day 20 of pregnancy caused two days later a significant increase in the ratio of the volume of remaining lobe of thyroid to body weight. The height of follicular cells was increased in a unilaterally thyroidectomized fetus when compared with that in a litter‐mate control fetus. In newborn rats, the unilateral thyroidectomy on day 1 of life also caused two days later a significant increase, though less than that observed in fetuses, in the ratio of thyroid volume to body weight. The height of follicular cells was not increased.The observations support the view that in the rat the pituitary‐thyroid system begins to function before birth and that the founctioning of the system is slightly reduced just after birth.
Relation between axial and appendicular skeletal calcium and body weight in the rat
Authors: Saville Paul D. , Smith Patricia M. 
Published: February 2005

AbstractThe total calcium content as well as the calcium content of individual long bones has been measured in male and female rats from weaning to maturity and were found to be linear functions of body weight in both sexes. The calcium content of the total skeleton was a constant percentage of body weight in males but was a continuously increasing percentage of body weight in females. The calcium content of the tibia and femur expressed as a percentage of total body weight changed ten‐fold between weaning and maturity in females but hardly changed at all in males. In mature animals above 250 gm, calcium is distributed in the different bones of the skeleton in the same proportions in both sexes though females contain much more calcium at any given body weight than males.
Effects of early postnatal androgen and estrogen injections on the estrous activity cycles and mating behavior of rats
Authors: Gerall Arnold A. 
Published: February 2005

AbstractInjections of 0.25 mg estradiol benzoate and 1.25 mg testosterone propionate in five day old intact and spayed albino female rats either eliminated or shortened the period of the estral activity cycle. Greater than normal amplitude of running was associated with neonatal estrogen and lower than normal activity with androgen. All of the oil‐ but none of the steroid‐treated females exhibited normal receptivity to vigorous males after hormone replacement therapy. It was concluded that neonatally administered steroids modified neural centers mediating behavioral periodicity and mating as well as those involved in gonadotrophin release.
Postnatal development of pulmonary and bronchial arterial circulations in the calf and the effects of chronic hypoxia
Authors: Reeves John T. , Leathers James E. 
Published: February 2005

AbstractSeven calves were placed in an altitude chamber on the day of birth and were maintained at the simulated high altitude of 11,000 feet for 2 to 5 months. Circulatory measurements during life and structural changes in the lungs after death were compared with findings in 20 normal calves. The normal calves showed a surprising growth of lung parenchyma and pulmonary and bronchial arterial circulations during the first seven days of life. Such a rapid postnatal lung growth has not previously been reported and may account for much of the normal decrease in pulmonary arterial pressure seen during this period of life. By contrast calves maintained from birth at simulated high altitude rapidly increased their pulmonary arterial pressures during the first two weeks of life. The pulmonary arterial circulation remained constricted and at autopsy presented an exaggerated radiographic and histologic pattern seen in normal calves less than 24 hours old. The bronchial arterial circulation in the calves at high altitude became greatly increased. Chronic hypoxia in these calves probably sustained increased tone in the pulmonary, but not systemic arterioles, with the result that the normal growth pattern of the lung vessels was altered. This study emphasizes the different regulation of the two arterial supplies to the same organ, namely, the lung.
The development of the arterial outflow tract in the chick embryo heart
Authors: Jaffee Oscar Charles 
Published: February 2005

AbstractBloodstream flow patterns have been outlined in the arterial outflow tract (ventricular outflow tract and bulbus arteriosus) of the chick embryo heart during the period in which septation takes place, Hemodynamic factors underlying flow changes during this period are discussed.The mapping of flow patterns did not support the concept of a conoventricular flange reported previously. Septation was found to take place between two separate and discrete bloodstreams.The cellular nature of the aorticopulmonary septum has been described. The spiral ridges that form this septum expand by cellular growth, explaining the ability of this septum to develop against the direction of blood flow. The aorticopulmonary septum divides about two‐thirds of the arterial outflow tract; the final partitioning of the most proximal portion of the outflow tract was found to take place by means of the apposition of endocardial cushion tissue masses.Failure of aorticopulmonary septum development (truncus arteriosus communis persistens) was found to follow fusion of the bloodstreams in experimental studies. In experimental aortic stenosis the appearance of a small left stream was found to be followed by the development of a stenotic aorta. Thus in the first instance the septum apparently cannot develop unless the streams remain separate and in the second case the size of the prhnordial bloodstreams appears to determine the diameter of the vessel.
Comparative anatomical and neurohistological observations on the tongue of slow loris (Nycticebus coucang)
Authors: Kubota Kinziro , Iwamoto Mitsuo 
Published: February 2005

AbstractOn the dorsum of the slow loris tongue there are three vallate papillae, arranged in an inverted V‐shape. They contain abundant plexiform nerves and isolated nerve cells but have many taste buds only in its sides, closely associated with the subgemmal nerve plexus. Some ducts of serous glands locating deeply in this region directly open on the upper surface passing through the papilla. No foliate papillae are observed in the posterolateral region of the tongue, but instead of them is found a papilla of fungiform type, which wholly contains abundant plexiform nerves and has a furrow without serous gland ducts and taste buds. Furthermore, its summit is at the same level as the surface and same as its base in diameter, and has embryonic taste buds. From these neurohistologic characteristics this papilla should be regarded as an interformed papilla between the foliate and the ordinary fungiform papillae. Tongue lyssa consisting of hyalin cartilage and striated muscles innervated with motor end plate and simple sensory nerves seems to play a role as receptive organ of the tongue. Underneath the tongue is found well‐developed sublingua, which consists of hyalin cartilaginous skeleton and mucosa but has no taste buds. From segmental arrangement of neurovascular spaces in the skeleton it may be an ancestral structure of the tongue.
Radioautographic studies of DNA synthesis in the developing extraembryonic membranes of the mouse
Authors: Saccoman Frank M. , Morgan Charles F. , Wells Lemen J. 
Published: February 2005

AbstractTritiated thymidine was injected into pregnant BALB/c mice intravenously at 8, 10, 12, 14 and 16 days of pregnancy. Radioautographs were prepared in order to determine the extent of synthesis of DNA in the extraembryonic membranes at the above stages of gestation. The extent of synthesis of DNA was expressed as a radioactive index. The index is the per cent of labeled nuclei in a population of 1000 observed nuclei. Radioactive indices were determined for the nuclei of the endodermal cells of the visceral yolk sac and of the parietal yolk sac, for the nuclei of the trophoblastic cells of the junctional zone and of the labyrinth and for the nuclei of the trophoblastic giant cells. The observations show that in all of the examined types of cells the synthesis of DNA is extensive at days 10 and 12 of gestation and that it is nearly completed by day 14.
Differences in thyroid activity in several inbred strains of mice
Authors: Mendoza Lorenzo A. , Hamburgh Max , Fuld Howard 
Published: February 2005

AbstractThe rate of daily secretion of thyroid hormone was compared in male mice of five inbred strains, the DBA/2, the C57B1/6, the St/6J, the CBA/J and the Swiss Albino strain.The method employed to measure thyroid secretion rates is based on a procedure which involves the production of goiters by daily propylthiouracil (PTU) administration in the drinking water and determining subsequently the effective dose of the exogenous thyroxin required to inhibit goiter development and maintain normal control weights of thyroid glands.Statistically significant differences were observed in output of thyroid hormone between the different genetic strains tested. The levels of thyroid activity were lowest in the temperamentally most active strains (DBA/2 and CBA/J) while the more placid strains exhibited higher levels of thyroid secretion (Swiss Albino and ST/6J).This unexpected finding is interpreted to indicate that, if there exists any correlation between thyroid hormone and behavior, the more active strains differ from the more placid ones in tissue sensitivity to thyroid hormone rather than in concentration of levels of circulating hormone.