bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of the metalophilic reticuloendothelial cells to cells containing acid phosphatase and non‐specific esterase in the lymphoid nodules of normal and stimulated rat spleens
Authors: Pettersen James C.
Published: February 2005

This study was undertaken to determine the relationship between Marshall's metalophilic reticular cells and the cells exhibiting non‐specific esterase and acid phosphatase activity in the rat spleen. Untreated and stimulated animals were used. Observations were made chiefly on the marginal metalophils of Snook. These cells showed strong acid phosphatase activity but only slight non‐specific esterase activity in untreated animals. Following stimulation non‐specific esterase activity increased in these cells. Within the nodules metalophilic reticular cells were always more numerous than cells with enzyme activity. Many of these metalophilic cells developed enzyme activity following stimulation. By the use of a restaining technique it was shown that all reticular cells possessing enzyme activity were also metalophilic but that the converse was not true. No mitotic activity was present in these cells.

The results suggest that Marshall's metalophils are cells of the reticuloendothelial system in various stages of maturation and that, following stimulation, they may differentiate into mature phagocytic cells.
Studies of muscle fibers of the tensor tympani of the cat
Authors: Erulkar S. D. , Shelanski M. L. , Whitsel B. L. , Ogle P.
Published: February 2005

The tensor tympani muscle of the cat has been studied using histological and electrophysiological techniques. Histological studies revealed the presence of striated and smooth muscle fibers. The striated muscle fibers could be classified structurally as “Fibrillenstruktur” and “Felderstruktur” fibers, suggesting that both “fast” phasic and “slow” tonic fibers were present. Histochemical studies showed that some of the smaller (25–40 μ) Fibrillenstruktur fibers possessed relatively large end‐plate receptor areas which stained heavily for acetylcholinesterase. The membranes and cytoplasm of even smaller diameter fibers (9–25 μ) stained for acetylcholinesterase, similar to its distribution in muscle spindles of other muscles.

Intracellular recordings showed that there were two distribution peaks of the resting membrane potentials — one at 40–50 mV, the other at 70–80 mV. When the nerve to the tensor tympani was stimulated by single square wave pulses, small junctional potentials (40 mV) followed by an after‐hyperpolarization, were recorded only from fibers with low resting membrane potentials — presumably slow Felderstruktur fibers. Large (70–90 mV) potentials which showed overshoot of zero potential, and which were preceded by initial long depolrizing potentials, were recorded from fibers with large resting membrane potentials. These fibers, which showed occasional spontaneous activity were presumably smooth muscle fibers. Potentials similar to those recorded from fast muscle fibers in other muscles were also occasionally recorded.

It was concluded that the cat tensor tympani possessed slow and fast striated muscle fibers, smooth muscle fibers, and possible some embryonic type muscle fibers.
Visceral heterotaxy with malformed heart. Similar findings in a child and a puppy
Authors: Ferencz Charlotte
Published: February 2005

A cyanotic child and a newborn puppy were found to have a complicated cardiac malformation of essentially identical design. There was situs inversus of the cardiac chambers, hypoplasia of the anatomic left heart with transposition of the great vessels, pulmonary atresia, patent ductus arteriosus and drainage of all pulmonary veins into the anatomic right atrium. There was situs inversus totalis with pivotal levocardia in the child and dextrocardia in the puppy.

The patient was markedly improved by a systemic‐pulmonary arterial anastomosis indicating the feasibility of palliative surgery in spite of the servere cardiac abnormality.

The association of visceral heterotaxy with an identical complicated malformation of the heart in the human and canine species appears to indicate a common developmental deviation and thus is considered to be of teratologic significance.
The effects of transection of the nerve trunk on the perineural epithelium with special reference to its role in nerve degeneration and regeneration
Authors: Shanthaveerappa T. R. , Bourne G. H.
Published: February 2005

Detailed histological and histochemical studies were made on the effect of transection on the perineural epithelium of the peripheral nerves of rat and cat. Histologically and histochemically it has been shown that the perineural epithelium does not undergo any change in the proximal as well as in distal segments of these transected nerves and is maintained as seen in the untransected nerves. These studies also show that the capsule of the muscle spindle is made up of a continuation of the perineural epithelium and maintains its histological structure, as well as its enzyme equipment. Electronmicroscopic evidences are given for the normal maintenance of this epithelium in the regenerating nerve. The only structure which does not show any change when a nerve is transected is the perineural epithelium. It has been pointed out that the perineural epithelial tube plays an important role in conducting the regenerating axons within the neurilemmal tube to the proper sensory and motor endings.
Responses of lymphocytes with “atypical nuclei” in the nodes proximal to parenteral injections
Authors: Tompkins Edna H.
Published: February 2005

Variable numbers of small lymphocytes with “atypical nuclei” have been shown to occur regularly in lymph nodes from normal animals. The present studies were carried out in explanation of these cells.

Mice were injected subcutaneonsly or intraperitoneally with physiologic saline or isotonic glucose, and with solutions of various organic substances in glucose. The draining nodes were fixed at various intervals thereafter, and unstained sections were examined by light and polarized microscopy.

These lymphocytes increased after all of the injections. The increments were moderate and of short duration after injections of saline and glucose alone, and the nuclei were morphologically similar to those found in the controls with the techniques employed. The increments were greater and more protracted after injections of most of the organic substances, and the morphology of the nuclei in polarized light differed from that of the normal. The effect on the morphology was influenced, in part, by the degree of solubility of the organic substance and the duration of exposure of the cells to it.

The conclusion is drawn that lymphocytes with “atypical nuclei” represent response to lymph drainage, in general, while modifications of their characteristic nuclear morphology are indicative of specific biologic responses.
In vivo measurements of capillaries of frogs, mice, and puppies
Authors: Beeler Henry S. , O'Brien David P. , Knisely William H.
Published: February 2005

The purpose of this study was to determine the dimensions of capilaries in various tissues, in vivo, in frogs, mice, and pups. Capillaries were measured in the web, strap muscles of the neck, mesentery and bladder of frogs, and in the mesentery of mice and pups. The light source was a fused quartz rod transilumination apparatus. In all cases the exposed tissues were kept moist by a continuous flow of Ringer's solution over their surfaces.

The mean values found for the tissues of the frog are web 11.94 μ, skeletal muscle 11.30 μ, mesentery 11.97 μ, and bladder 11.40 μ. The mesenteric capillaries of the mice and pups had a mean value of 4.64 μand 7.36 μ respectively.

Difficulties encountered during the course of observation included vibrations of the optical equipment, movement of the tissue under the microscope, fogging of the objective lens, and the determining of which of the microscopic vessels were “capillaries.”

A statistical analysis of the data indicates that the variance in the measurements recorded on the capillaries of a single animal is greater than the variance from animal to animal.
Prenatal development of the mandibular joint in mice
Authors: Frommer Jack
Published: February 2005

The prenatal development of the mandibular joint in mice was studied in fetuses at 15 to 20 days insemination age. The ramus of the mandible can be delineated as early as the fifteenth day by distinct differences in the degree of condensation of mesenchyme at the site of the future joint. The future condylar process of the mandible can be recognized in its relationship to the external pterygoid muscle, inferior alveolar nerve, Meckel's cartilage, pre‐cartilaginous alisphenoid process of the future basisphenoid bone, and the anlage of the squamosal bone with its zygomatic process.

Differentiation is rapid through the twentieth day of gestation at which time the following major elements of the joint can be recognized: a fibrous intra‐articular disc continuous with the tendon of the external pterygoid muscle; a vascular synovial mesenchyme with upper and lower synovial spaces; an ossified squamosal bone with a fibrous joint lining; and a well developed condylar process with good representation of differentiating cells in the zones of chondrification and ossification.

Among the elements not yet evident, however, are (1) hemopoietic marrow in the condyle, (2) a constricted neck at the base of the condyle, and (3) a fibrous capsule or capsular ligament.
The autofluorescent cells of the lymphocytic tissues of the rat
Authors: Sainte‐Marie Guy
Published: February 2005

The lymphocytic tissues of normal rats were fixed in cold alcohol and embedded in paraffin. Unstained sections were examined under the fluorescent microscope. The sections were stained, thereafter, by various techniques.

Peculiar “autofluorescent cells” were found at the cortico‐medullary junction of each thymic lobule, associated with lymphocytic nodules, and, in the plasmocytic medullary cords of the nodes. These cells contain numerous yellow autofluorescent granules and a few blue ones. The amount of yellow granules increases in the lymphocytic organs of pregnant rats. The granules stain positively with Sudan black B and P. A. Schiff techniques, and stain pale green with toluidin blue.

Comparison reveals that the “autofluorescent cells” correspond to the “Lipid‐laden foamy cells” described by Loewenthal and Smith and to the “PAS‐positive reticulum cells” of Metcalf. Unlike Loewenthal et al. it is concluded that these cells are not arising from thymic involution. Metcalf's conclusion that these cells control thymic lymphocytopoiesis is analyzed in view of new findings and his conclusion is questioned. The development of the autofluorescent cells is shown to somehow parallel the development of post‐weaning growth and of immunity. The possible function of the autofluorescent cells in both phenomena is discussed.
The leucocyte‐like cells of the oviducts during the normal estrous cycle and their modification by progestin and estrogen treatment
Authors: Nellor John E.
Published: February 2005

During specific phases of the luteal stage of the estrous cycle, and during early pregnancy, or following progestational administration, there is a marked mobilization of lymphoblast‐like cells in the connective tissue of the plica. These cells readily penetrate the basment membrane, and assume an intercalary position in their migration between the epithelial cells to the lumen. Progestational treatment intensifies this migration during the luteal phase of the estrous cycle in the normal animal, or induces this migration in the oviducts of the ovariectomized animal. Estrogenic treatment alone, in the ovariectomized animal, will not maintain the migration of lymphoblast‐like cells in the connective tissue of the oviduct, nor their penetration between the epithelial cells and extrusion into the lumen of the tissue. Estrogenic treatment induces a marked modification of the lymphoblast‐like cells mobilized by progestational treatment, resulting in morphological reorganization and destruction of the cells in the oviductal tissues. The morphological reorganization of the cell is noted in eosinophilic granulation of the cytoplasm, followed by fragmentation of the nuclear chromatin within the cell. The eosinophilic granulation is lost, followed by dissolution of the nuclear and cytoplasmic membranes and scattering of the chromatin material into the tissue.
Origin of hypoglossal muscles in the chick embryo
Authors: Hammond Warner S.
Published: February 2005

In this study, experiments are described in which part cr all of the occipital somites were removed from chick embryos of 8 to 25 somites. The embryos were reincubated and sacrificed 6 to 9 days after the operation. Adequate extirpations of somites 2 through 6 resulted in absence or depletion of one or more of the hypoglossal muscles, thus demonstrating their somtic origin from these levels. Somite 1 disappears early and does not make a contribution to the hypoglossal muscles. The optimal stages for operation are between 8 to 15 somites.
A study of postnatal growth of skeletal muscle in the rat
Authors: Chiakulas John J. , Pauly John E.
Published: February 2005

From each of five litters of Sprague‐Dawley rats, littermates were sacrificed at 1, 3, 6, 12 and 24 weeks of age. The musculi extensor carpi radialis longus, soleus and plantaris were treated with glycerine while attached to the extremities and then dissected out and fixed in formalin. A transverse section through the thickest portion of the belly of each muscle was projected by a microprojector on graph paper. The entire section and the individual muscle fibers in representative areas within it were outlined. From this the total cross sectional area of the muscle; the number of fibers contained within it; the size, in terms of cross‐sectional area, of fibers; and the ratio of muscle to connective tissue were calculated.

As the animals mature, there is an enlargement of the cross‐sectional area of the entire muscle and of the individual fibers. There is a definite increase in the number of muscle fibers during the first three weeks after birth which is the result of the differentiation into myofibers of myoblasts present in muscle fiber bundles at birth. A steady increment in the percentage of muscle to connective tissue throughout the entire growth period is present.
The arterial supply of the dura mater of the rhesus monkey
Authors: Castelli Walter A. , Huelke Donald F.
Published: February 2005

A study of the dural blood supply in 20 specimens by dissection, corrosion preparations and cleared specimens indicates that the dural arteries are similar to those of man yet significant differences were noted. The anterior cranial fossa is supplied by small twigs which spread through the dura of the anterior cranial fossa floor. The larger branch, the anterior meningeal artery, perforates the lateral orbital wall and supplies the lateral wall of anterior and middle cranial fossae. The middle meningeal artery, of the maxillary artery, divides into two branches in the floor of the middle fossa. The anterior or frontal branch always anastomoses with the anterior meningeal artery. Sometimes it also continues upward to the lateral wall of the middle fossa to supply it. The posterior middle meningeal branch passes backward to supply the parietal area. The posterior meningeal artery, of the occipital artery, enters the skull near the beginning of the sigmoid sinus and follows the general course of the lambdoidal suture.
The human egg in the pronuclear stage
Authors: Dickmann Z. , Chewe T. H. , Bonney W. A. , Noyes R. W.
Published: February 2005

A human egg in the pronuclear stage was recovered by flushing the excised oviduct that had been removed along with the uterus. The hysterectomy and right salpingectomy were performed on day 16 of the patient's menstrual cycle. The egg was examined first in the fresh state and revealed two pronuclei, a granular zona pellucida, and corona cell processes traversing the zona pellucida. The egg was subsequently fixed and stained revealing further details of the pronuclei, and the tail of the fertilizing spermatozoon lying over one of the pronuclei.

The age of the egg was estimated as being 3 to 50 hours post ovulation time.
Ciliated cells in the spleen of adult rats
Authors: Abdel‐Bari Waguih , Sorenson George D.
Published: February 2005

During a study of the effects of 600 r whole body x‐irradiation on male adult Sprague Dawley rats, rare cilia have been noted on reticular cells of normal and x‐irradiated rat spleen. They are of the 9+0 pattern and appear similar to those previously noted in other cells. The functional significance of these cilia is unknown.
Induction of pseudopregnancy in the rat by vaginal stimulation at various stages of the estrous cycle
Authors: Staples R. E.
Published: February 2005

Normally‐cycling female rats were electrically stimulated at various stages of the estrous cycle to test the effectiveness of a modified probe for the induction of pseudopregnancy. The ability to form decidua served as the criterion of successful response. The probe was constructed to deliver a cervical‐vaginal or vaginal‐vaginal stimulation rather than the usual cervical‐cervical stimulation. The electrical stimulus used consisted of 50 v at 200 pps for a five‐second duration. It was found to be effective throughout vaginal estrus but was much less effective during early and late proestrus or early metestrus. Placement of electrodes on the vaginal wall during stimulation was shown to be as effective as placing them on the cervices. As a result, rats may now be made pseudopregnant without visual placement of electrodes thereby simplifying and hastening the stimulation procedure and rendering it more suitable for routine use. Only 20–25 seconds were required to stimulate each animal.
In vitro development of tooth rudiments of embryonic mice
Authors: Koch William E.
Published: February 2005

Embryonic mouse mandibular tooth rudiments, completely excised from the host and placed in vitro at a “glass‐plasma clot” interface, fail to develop normally. The organization of the rudiment is destroyed by migration of cells into the cloth. Rudiment morphology is maintained and histodifferentiation occurs when such rudiments are grown on artificial filter membranes. In cultures of 16 day embryonic incisors, a “refractile” material is noted on the distal‐incisal‐labial side of the developing rudiment after three days in vitro growth; this material increases in extent during subsequent growth. Histological sections show normal differentiation of the cells of the rudiment; extracellular matrices are deposited by the odontocytes and also by amelocytes. The position of amelocyte matrix correlates with that of the “refracticle” material seen in the living culture. The sequence of changes during cellular differentiation in vitro corresponds to that occurring in vivo.
Effect of insulin antibodies on pancreatic islet insulin and beta cell granule content
Authors: Morgan Carl R. , Carpenter Anna‐Mary , Lazarow Arnold
Published: February 2005

Normal rats injected intravenously with anti‐insulin guinea pig serum (AIS‐GP) exhibited a marked hyperglycemia which reached a maximum (>300 mg per 100 ml) at the third hour. The blood sugar was 172 mg per 100 ml by the eighth hour and was normal (100 mg per 100 ml) at 24 hours. Control animals injected with equal quantities of normal guinea pig serum did not show significant changes in blood sugar.

In pancreatic tissue obtained from rats three hours after injection of AIS‐GP the aldehyde‐fuchsin staining granules of the beta cells were significantly fewer than in the controls. Quantitation studies indicated that in the AIS‐GP injected animals 26% of the islet volume was composed of 4+ and 3+ granulated beta cells as compared to 68% for rats injected with normal guinea pig serum. The cell granulation was normal 24 hours after injection of AIS‐GP. Electron microscopic studies confirmed that this decrease in aldehyde‐fuchsin staining was due to degranulation.

The insulin content of microdissected islets obtained three hours after injection of AIS‐GP was significantly lower than that of the controls. The mean value (immunoassay determinations) for the AIS‐GP injected animals (89±30 units per gm dry weight of islet) was 38% that of the controls (232±66).
The cell web in the ameloblasts of the rat incisor
Authors: Kallenbach E. , Clermont Y. , Leblond C. P.
Published: February 2005

The ameloblasts (and associated cells) of adult rat incisors were examined in sections stained with tannic acid‐phosphomolybdic acid‐amino black (TPA), a method which demonstrates the fibrillar structures of cytoplasm referred to as cell web, as well as terminal bars and desmosomes. These structures were analyzed at various stages of the life cycle of ameloblasts.

The first sign of a cell web is found in the immature ameloblasts observed toward the end of the proliferation zone. Delicate vertical fibrils appear, which persist in various forms throughout the zones of differentiation, secretion, post‐secretion, pigmentation and regression. These vertical fibrils are present along the lateral cell wall in most zones. In the post‐secretion zone, a coarse fiber appears in the axis of the cell within the supranuclear region. This fiber splits at both ends into fine fibrils running toward the apex and base of the ameloblast, where delicate desmosomes are visible.

A first set of terminal bars arises at the base of ameloblasts in the zone of proliferation. These “basal” terminal bars persist in all except the regression zone. A second set of terminal bars appears at the apex of the ameloblasts in the zone of differentiation. These “apical” terminal bars reach their maximal development in the secretion zone and disappear in the regression zone. Finally, desmosomes are prominent in the post‐secretion and pigmentation zones, mainly on the apical and basal surfaces of the cells.

The staining of terminal bars and desmosomes with TPA is presumably due to the accumulation of cell web fibrils on these attachment sites. The cell web may impart rigidity to the cell and provide resistance to stress wherever the fibrils are inserted on desmosomes and terminal bars.
Transcallosal connections of the cingulate gyrus in monkey
Authors: Locke Simeon , Kruper Donald C.
Published: February 2005

The intercingulate connections of the Macaque hemisphere were studied by the Loyez and cresyl violet techniques in 15 specimens 19 to 29 months following hemicerebrectomy. Demyelination and pathological gliosis in the posterior part of the corpus callosum were traced to the upper crown and bank of the cingulate gyrus. LC3 cortex, from which cingulum fibers arise, was devoid of these changes. The gliosis increased superiorly toward medial parietal cortex. Examined in light of known thalamic projections it appears that in general there is an inverse relation between the number of commissural connections and the thalamic afferents.
Changes in the relative organ weights in the fetal dog
Authors: Latimer Homer B.
Published: February 2005

Changes in the relative percentage weights of the organs in 187 fetal and 24 newborn dogs are presented. Nine organs increase less in total weight during fetal life than total body weight. These are, in increasing order: spinal cord, brain, suprarenals, testes, hypophysis, heart, thyroid, urinary bladder and liver. Increasing more than body weight and in increasing order are: ovaries, digestive system, uterus, spleen, lungs, thymus, digestive tube, kidneys and pancreas. No adult weights were found for seven of these, but the increases to adult weight are shown for the other organs.

The organs increasing less than body weight decrease in relative percentage weight rapidly at first and then more slowly throughout fetal life and all of these, except the heart and spinal cord, decrease in percentage weight in the adult.

Organs increasing more than body weight have their most marked increase in the early part of fetal life. Thus the relative organ weights are changing most rapidly in early fetal life with more gradual changes toward the end. The spleen and pancreas manifest the most marked and continued increase, while the cord, suprarenals, brain and testes decrease most precipitously in early fetal life. The kidneys, lungs and ovaries have their maximum percentages at birth.

These relative changes are compared with similar relative changes in man and in the cat.
A catenary analysis of the maxillary dental arch during human embryogenesis
Authors: Burdi Alphonse R. , Lillie John H.
Published: February 2005

Human embryos aged six and one‐half through 1 weeks were studied to determine the morphological changes in shape of the maxillary dental arch during this early developmental period. Age was determined by crown‐rump lengths using the table of Patten ('53).

When compared to a reference catenary curve, the embryonic dental arch exhibited several time‐linked and directional changes in shape. First, 6.5 to 8 week embryos characteristically had upper dental arches which were wide and anteroposteriorly flattened and did not conform to the catenary curve. At 7.5 to 9 weeks, the C‐shaped dental arch showed more elongation and increasing depth. It was not until weeks 9.5 to 12 that the embryonic dental arch grew enough to conform to the catenary curve.

It is suggested that the catenary curvature of the postnatal upper dental arch can be first recognized as early as 9.5 weeks of development.
Cells with filopodia cultured from human synovialis
Authors: Stanfield A. B.
Published: February 2005

In Rose chamber primary explant cultures of synovialis from 11 patients, large cells with motile filopodia have been observed and documented by both still and cinéphotomicrographs. Frequently the tips of the filopodia are attached to the glass surface of the cover slip in the Rose chamber. A continuous, tremulous motility is referred from this point of attachment to the cell itself. Mitosis has not been observed in the cells with filopodia although they have persisted in culture for as long as 171 days. Explants from a total of 376 individuals have been studied: 144 from rheumatoid arthritis patients and 232 from nonrheumatoid patients. Cells with filopodia were observed from only 11 explants (2.9%): eight were rheumatoid; and three were nonrheumatoid.
Goblet cell fine structure
Authors: Freeman James A.
Published: February 2005

Although the role of the goblet cell in mucous secretion has been known since 1837, the actual process by which mucous is formed by the cell still is open to question. There is a known proliferation of the Golgi membranes during the early formation of mucous within peripheral Golgi vacuoles. However, there also is a concomitant proliferation of rough‐surfaced endoplasmic reticulum which contains an electron dense material within the lamellae. It is suggested that the endoplasmic reticulum synthesizes a protein moiety which is transported to the Golgi apparatus. There the protein is combined with acid mucopolysaccharides and glycoproteins, that are synthesized by the Golgi apparatus, to form the mucous droplets visible in the electron microscope.

Examination of intestinal goblet cells of man, rat, and guinea pig, after stimulation of the cells to evacuate their mucous, also reveals a basic fine structure that clearly is distinguishable from the fine structure of columnar absorbing cells.
The human aortic ridge and cushion
Authors: Parke Wesley W. , Michels Nicholas A.
Published: February 2005

A ridge of fatty tissue partly encircles the midsection of the human ascending aorta. This structure was constant in occurrence, position, and form in all examined adult and late fetal specimens. The ridge terminates as an expanded cushion that is situated on the right wall of the aortic bulb in apposition to the edge of the right auricle. A fascial cleft beneath the cushion permits a mobility which would enable the structure to relieve pressure and friction caused by the expansion of the auricle against the aorta. A vascular plexus within the cushion is formed by the anastomoses of the coronary and extracardiac branches of the aortic vasa vasorum.
Histological observations on the ovary of the white‐tailed mole, Parascaptor leucurus
Authors: Duke Kenneth L.
Published: February 2005

The 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

The 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

A 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

The 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

A 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

In 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

Little 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

Rabbit 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

Microcirculation 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

The 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

The 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

Measurements 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

The 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

Injections 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

Seven 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

Bloodstream 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.