bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of unilateral ovariectomy on ovulation and cycle length in 4‐ and 5‐day cycling rats
Authors: Peppler Richard D. , Greenwald Gilbert S. 
Published: February 2005

AbstractCyclic rats were unilaterally ovariectomized on each day of the estrous cycle and the ovulation rate of the remaining ovary was determined at the next expected ovulation by counting tubal ova.Holtzman rats, followed for three successive estrous cycles, were classified as 4‐ or 5‐day cyclic animals. Control (i.e., intact) 4‐day animals ovulated (2 ovaries) an average of 9.6 ± 0.6 eggs and 5‐day rats ovulated 10.2 ± 0.2 ova. Estrus was designated as day 1 of the cycle. Unilateral ovariectomy on the morning of days 1 to 3 resulted in doubling the number of ovulations (complete compensatory ovulation) by the next estrus in all rats: an average of 10.5 eggs (N = 78 animals). Four‐day animals did not compensate when semi‐spayed after 8 PM of day 3, whereas, 5‐day aniamls continued to double the number of ovulations until 2 AM of day 4.Unilateral ovariectomy of rats with previous 5‐day cycles between 8 and 12 AM on day 1 shortened the expected cycle length by one day (60/73 rats). In contrast, only 19.4% of intact 5‐day rats, spontaneously shortened their fourth cycle to four days. This effect of unilateral ovariectomy was only apparent in the cycle in which the operation was performed and was preventable by administration of 0.5 to 2.0 mg of progesterone on day 2. This suggests that unilateral ovariectomy on day 1 may have reduced the level of circulating progesterone enough to facilitate the release of LH one day earlier in the estrous cycle.
Some histological features of avian kidneys
Authors: Johnson Oscar W. , Mugaas John N. 
Published: February 2005

AbstractThe avian kidney is composed of cortical and medullary lobules, with the former surrounding branches of the renal vein. Cortical lobule diameters varied intraspecifically according to level of association with the venous system, and interspecifically were greatest in nonpasserines. All cortical tissue examined contained maculae densae.Each medullary lobule receives collecting ducts and loops of Henle from several cortical lobules. Such a complex may be viewed as a lobe, and the entire kidney as multilobar. The relative diameter of a medullary lobule appears directly related to the number of cortical units with which it is associated. Distally, most lobules vary from 0.3 to 0.5 mm in diameter, and contain 20 to 30 collecting ducts. The latter fuse dendritically as they traverse a medullary unit, and eventually form ureteral branches which drain directly into the ureter.Intramedullary organization in passerines involves aggregated thin limbs bounded by collecting ducts which in turn are surrounded by uneven layers of thick limbs. While some nonpasserines approach this pattern, others lack apparent organization of intramedullary elements. The turn of Henle's loop was restricted to the thick limb in all birds examined. Avian and mammalian thick limbs are similar in diameter, but avian thin limbs are typically wider.Small kidneys have short ureteral branches with primary stems clustered in each kidney division. In larger kidneys, where medullary lobules are often remote from the ureter, ureteral branches are long and not clustered.
Splenic megakaryocytes and circulating platelets in pregnant rats
Authors: Marien G. J. , McFadden K. D. 
Published: February 2005

AbstractA comparative study of the hemopoietic tissues and blood of non‐pregnant and pregnant rats of graded duration of gestation was undertaken and the results were compared with those obtained on postsplenectomized rats at similar stages of pregnancy. The number of megakaryocytes was determined in representative fields of the liver, spleen and bone marrow. Platelet counts were performed on blood collected from the venae cavae of these rats using a modified Rees‐Ecker technique.The liver of normal adult animals, pregnant or non‐pregnant, does not reveal megakaryocyte production. Although bone marrow is the most active site of megakaryocytopoiesis in the adult animal there is only a slight numerical increase in megakaryocytes during pregnancy. The most dramatic change occurs in the spleen of the pregnant rats and is reflected by increased splenic weight and increases in red pulp and in the number of platelets circulating in venous blood. Splenectomy of the rat produces an abrupt increase in the number of circualting platelets which is not sustained into the later postoperative period when platelet counts below those of control animals are found. When pregnancy occurs in the later postoperative period, the splenectomized rat develops a trend toward increased platelt counts but these never reach the level obtained in nonsplenectomized pregnant rats.
Activation of pain pathways in animals
Authors: Mahan Parker E. , Anderson Kenneth V. 
Published: February 2005

AbstractIn analyzing the anatomy and physiology of sensory systems it is often necessary that one activate the particular system being studied with appropriate stimulation. In experiments where this is necessary, the stimulation presented should be specific to the sensory system under study. With the pain system, however, this is most difficult since most stimuli that activate pain pathways also activate other pathways such as those that mediate touch and pressure sensations. It is also helpful to have available a stimulation technique that can be used in both acute experiments and long term neurophysiological and behavioral experiments. For investigation of the anatomical substrates of pain perception, a technique has been developed for implantation of bipolar electrodes in the teeth of cats that permits one to stimulate the tooth pulp in acute or chronic preparations, and, thus, to activate a pain pathway exclusively and directly. This technique provides a stimulus that is readily quantifiable, easily controlled, entirely nociceptive in character, and which can be used in a wide variety of situations.
Denervation of taste buds in the rabbit
Authors: Naga Ibraheim A. , Sakla Francois B. , Girgis Zaiful A. , State Fathy A. 
Published: February 2005

AbstractTwenty‐five rabbits were used to study the effect of glossopharyngeal nerve transection upon the number, size and cellular constitution of the taste buds. The glossopharyngeal nerve was cut on one side, the other being left undisturbed as a control. The animals were sacrificed in groups of three after 7, 10, 14, 21, and 30 days, and 2 and 4 months after the operation. Seven days after the operation the size and number of intragemmal cells were decreased in the taste buds. The taste pores with hairlets passing through them disappeared. The number of taste buds on circumvallate papillae decreased. After ten days taste buds in both types of papillae showed signs of degeneration. Fourteen days after the operation there was a marked decrease in size and number of taste buds. The circumvallate papillae now possessed no taste buds. After 21 days few taste buds were present in foliate gutters. These consisted of one or two sustentacular cells each. After 30 days there were no taste buds on foliate papillae, and thickness of the epithelium lining the gutters was decreased. Two or four months after denervation, the foliate gutters were shallow and some had become flattened. The importance of the gustatory nerve for development and maintenance of the normal status of the taste buds is discussed.
Electron microscopic observations of the nucleus, glial dome, and meninges of the rat acoustic nerve
Authors: Ross Muriel D. , Burkel William 
Published: February 2005

AbstractThe rat acoustic nerve is separated into central and peripheral portions by an astrocytic glial dome which is convex peripheralward. The long central portion is of typical central nervous system structure with narrow extracellular space (100–200 Å in width), oligodendrocytes and astrocytes. The glial dome is penetrated by acoustic nerve fibers at a node of Ranvier; the basal lamina of the astrocytes is reflected back over the peripheral Schwann cells at this site. Centrally, the myelin is thinner than peripherally.Acoustic nerve neurons, ranging in size from 25–60 μ, occur in the central portion of the nerve and may be divided into two groups based upon size and density of organelles: large and medium‐sized. All the neurons possess an eccentric nucleus and a peripheral clear zone in the perikaryon beneath which Nissl substance is aggregated, but the medium‐sized neurons have fewer organelles than the large cells. Dendrites and axons are similar in ultrastructure.While collagenous fibrils, fibroblasts, Schwann cells and extensive extracellular space occur in the peripheral portion of the nerve, no structure corresponding to perineurium or epineurium exists. Instead, dura mater surrounds the acoustic nerve within the modiolus and the pia mater encloses bundles of nerve fibers up to the modiolar foramina where it is reflected back as arachnoid mater. Nerve fibers traversing the modiolar foramina are devoid of a meningeal or perineurial covering; this condition also prevails in the osseous spiral lamina, although wisps of pia‐like cells enclose groups of ganglion cells and nerve fibers in the spiral tract. These findings may help to explain acoustic nerve involvement in pathological processes such as meningitis and encephalitis.
The morphogenesis of the lateral nasal wall in the early prenatal life of man
Authors: Vidić Branislav 
Published: February 2005

AbstractTo study the fetal morphogenesis of the lateral nasal wall and nasal conchae as well as the initial development of the paranasal sinuses, 15 specimens were investigated. Their crown‐rump lengths ranged from 25 to 263 mm. The specimens were fixed in Bouin's solution. Serial sections were stained with hematoxylin and eosin, and Mallory's trichrome stain. The objectives were to ascertain the time and course of development of: (1) ossification in the maxilla and palate, (2) formation of the nasal capsule and the conchae, (3) chondrification and ossification in the nasal capsule and conchae, (4) the maxillary sinus and ethmoidal cells, and (5) glands in the respiratory mucosa. The earliest appearance of the conchae was observed in a 25 mm CR fetus. In a 32 mm CR fetus, ossification in the maxilla and palate was begun and the first maxillary sinus primordium was observed. The glands associated with the maxillary sinus and the inferior concha developed in a 49 mm and in a 90 mm CR fetus, respectively. The ethmoid and three conchae started to ossify in a 160 mm CR fetus. It was concluded that the transformation of mesenchyme into the bony skeleton was accomplished in a 263 mm CR fetus. Both groups of paranasal sinuses and the respiratory glands in the 263 mm CR fetus were morphologically well differentiated. In addition to an extensive survey of the literature, the possible role of the mucosal glands in development of the paranasal system was discussed.
The development of the chorio‐allantoic placenta of the African scaly‐tailed squirrels (family Anomaluridae)
Authors: Luckett W. Patrick 
Published: February 2005

AbstractThe affinities of the isolated rodent family Anomaluridae are unknown. Both sciuromorphous and specialized features characterize its placental morphology. A shallow preplacenta consists of inner cytotrophoblastic and outer syncytiotrophoblastic layers. The early chorio‐allantoic placenta consists of the following zones: a hemochorial zone of interconnected trabeculae, lined with outer syncytiotrophoblastic and inner cytotrophoblastic layers; anchoring trabeculae attached to a zone of decidual giant cells, with the giant cells gradually disappearing in later stages; a zone of acidophilic, PAS‐positive necrotic material underlying the giant cells; and a zone of decidua basalis underlying the necrotic zone and probably contributing to it. An allantoic vesicle lies on the surface of the early placenta; it is reduced in later stages. The bilaminar omphalopleure persists, and it is attached to the margins of the placental disc. The fetal membranes of Anomalurus are most similar to those of sciuromorphs, Pedetes and Ctenodactylus; this may be the result of primitive retentions.
Anchor filament bundles in embryonic skin: Origin and termination
Authors: Kischer C. W. , Keeter J. S. 
Published: February 2005

AbstractDuring development and maturation of skin and its derivatives, bundles of extracellular filamentous elements appear, which traverse a cross section of dorsal skin from deep mesenchyme to the basal lamina of the dermo‐epidermal junction. Observations on freshly fixed tissue and on pieces of skin grown in culture for three to five days, especially in areas where the presence of anchor filaments could be predicted, indicate that the filaments most likely originate from fibroblasts which are usually located in a stratified layer of the deeper mesenchyme. The distal end, or termination, appears to be the basal lamina into which the anchor filament blends and is dispersed.The anchor bundles are composed of long thin filaments in close aggregation and they demonstrate cross‐striations separated by approximately 400 Å in the midportions, and up to 600 Å near their origin and termination. The diameters of the bundles average approximately 0.33 μ at their thickest part. However, at or near their origin, they measure 0.2 μ or less in diameter.The analogy of the filaments to a growing tree is suggested in that, the roots, or origins of the filaments are thin, tortuous and in many cases widely separated. In certain areas they converge into one main trunk which tapers toward their termination in the basal lamina. The observations also suggest that some bundles may have several roots or rootlets, while others have only one or two.Although collagen is often seen close to the bundles, the data indicate that the latter are distinct from, and not derived from collagen.
Protein absorption by the guinea pig chorioallantoic placenta
Authors: King Barry F. , Enders Allen C. 
Published: February 2005

AbstractPrevious experiments have suggested that the guinea pig chorio‐allantoic placenta is a barrier to the maternal‐fetal passage of proteins. The means by which the placenta exercises this barrier function were investigated by electron microscopy after injection of peroxidase, ferritin, and Thorotrast. Uptake of protein was by coated vesicles which formed at the trophoblast surface, pinched off, and migrated deeper into the cytoplasm. Some vesicles emptied into multivesicular bodies; others migrated across the trophoblast, emptying their content into the underlying compartment. Peroxidase and ferritin were observed in basement membranes within 10–20 minutes after injection. At longer intervals, the proteins were increasingly difficult to demonstrate in basement membranes, although increased amounts were present in the trophoblast. Neither the basement membranes nor the fetal capillary endothelium constituted an effective barrier to proteins which crossed the trophoblast. The results suggest that the trophoblast is the major barrier to maternal‐fetal protein transfer across the labyrinth. The trophoblast appears to exercise this barrier function by (a) having a low rate of protein absorption and (b) having multivesicular bodies and lysosomes which sequester and possibly degrade absorbed proteins. However, the trophoblast is not a complete barrier to the passage of these exogenous proteins which may indicate a normal, albeit minor, pathway of maternal‐fetal protein transport.
The fine structure of developing cartilage in the chick embryo
Authors: Olson Mark D. , Low Frank N. 
Published: February 2005

AbstractThe fine structure of developing cartilage is described in the area of the future vertebral bodies in the cervical region of chick embryos. Incubation ages range from 36 hours, when the sclerotome of the somite begins to break up, to the thirteenth day. In the 36‐ to 72‐hour interval cells of the sclerotome become free and assume stellate form. Polyribosomes nearly fill the largely undifferentiated cytoplasm. Microfibrils and amorphous material appear in the connective tissue spaceThe extent of the connective tissue space is determined by boundary (basement) membranes; externally by those of epithelium facing the geometric exterior of the organism and internally by those of endothelium, mesothelium, muscle, nerve and fat. The true contents of the connective tissue space are the connective tissues. As used in this paper “connective tissue space” refers to the extracellular portion, in which the fibrous and amorphous components exist.
by the end of the third day. From the fourth through the sixth day both cellular contours and contents suggest fibroblasts. Microfibrillar diameter increases from 50 to 150 Å. Periodicity does not occur. Matrix granules appear and establish contact with microfibrils. From the eighth through the eleventh day the predominating cell types are chondroblasts and chondrocytes whose fine structure is typical. Microfibrils become more numerous and matrix granules larger. During days 11 through 13, chondrocytes show degenerative changes including lucid areas of nucleoplasm and cytoplasm with fragmentation of endoplasmic reticulum. Microfibrils and matrix granules are heavily concentrated in the connective tissue space and lucent osteoid appears.
Blood supply of human fetal teeth
Authors: Tobin Charles E. 
Published: February 2005

AbstractInjection studies were made of the blood vessels of developing human teeth, using 114 unfixed aborted fetuses and new‐born infants ranging in gestation age from three through nine months. These specimens were injected with India ink‐formalin, Micropaque‐formalin, Microfil, or vinyl acetate solutions via the umbilical vessels; in cases where an autopsy had been performed, injection was made through the carotid artery. After further fixation by immersion in 10% neutral formalin, the head was bisected in the sagittal plane. One half was dissected and tissue obtained for microscopic study; the other half was radiographed, dissected or dehydrated and cleared. These techniques revealed that the plexus of vessels which surrounds the developing dental organs is derived mainly from the inferior alveolar and palatine arteries, respectively. However, branches from vessels in adjacent tissues also supplied this plexus. The teeth growing most rapidly, and which usually erupt the earliest, receive the largest blood supply.Odontoblasts were supplied by vessels which course through the dental pulp to their deeper surface. The ameloblasts were adjacent to vessels in the capillary plexus on the outer surface of the enamel organ. A venous sinus was located at the base of the dental organ.
Effects of a bacterial vaccine on the marginal zone of the spleen
Authors: Clark Junius M. , Weiss Leon 
Published: February 2005

AbstractThe effect of systemic administration of a typhoid vaccine (T.A.B.) on the marginal zone of rat spleen has been investigated by light and electron microscopy. This bacterial preparation damages granulocytes in the circulating and marginated pools and the damaged cells are sequestered in the spleen, particularly in the marginal zone. The activities of the vaccine are attributed to its endotoxic properties. Terminations of arterial vessels in the marginal zone are also described.
Cell replication of mesenchymal elements in adult tissues. II. Replication of smooth muscle cells in the colonic muscularis externa of adult rabbits
Authors: Kaye Gordon I. , Siegel Linda F. , Pascal Robert R. 
Published: February 2005

AbstractAutoradiographic determination of the number and distribution of replicating cells in the colonic muscularis externa of adult rabbits was carried out, using animals sacrificed between 11 minutes and 14 days after a single‐dose‐pulse of 3H‐thymidine; or using animals sacrificed between two hours and 21 days after a multiple‐dose‐pulse of 3H‐thymidine. Labeling of smooth muscle cells was seen as early as 11 minutes after injection. By two hours after a multiple‐dose‐pulse more than 0.3% of the cells of the colonic muscularis externa were heavily labeled. Both the number of labeled cells and the number of labeled pairs, triplets and nests of cells increased with time after injection of 3H‐thymidine. There was a very regular reduction in grain count per nucleus during the 21 day period. No regular migration away from the site of division was observed.This tissue, like the tunica media of blood vessels and the panniculus adiposus, exhibits independent replication and no migration. The colonic muscularis externa can be classified as a slowly renewing population.
Ultrastructure of the corpus luteum of the white‐tailed deer during pregnancy
Authors: Sinha Akhouri A. , Seal Ulysses S. , Doe Richard P. 
Published: February 2005

AbstractThe fine structure of corpora lutea from 14 white‐tailed deer was studied from early through near‐term pregnancy. The corpora contained both thecal and granulosal lutein cells. The small, elongate and cylindrical thecal lutein cells contained many lipid droplets, juxtanuclear Golgi elements, abundant agranular endoplasmic reticulum, and other cytoplasmic organelles. These cells were observed throughout pregnancy. Some of the thecal lutein cells became modified during early to midpregnancy. The modified thecal lutein cells possessed many lipid droplets, several lysosomes, packets of PAS‐positive glycogen granules, and numerous small membranous whorls of agranular endoplasmic reticulum. The granulosal lutein cells had highly folded and/or ruffled plasma membranes, abundant tortuous tubular and cisternal agranular endoplasmic reticulum, numerous rod‐shaped to round mitochondria with tubular and lamellar cristae, Golgi elements, and a few packets of granular endoplasmic reticulum. Many granulosal lutein cells became modified during mid‐ to near‐term pregnancy by the addition of numerous small membrane‐bound osmiophilic droplets and variable numbers of large nonmembrane‐bound lipid droplets. The granulosal and thecal lutein cells appeared more active in steroid biosynthesis than the modified granulosal and thecal lutein cells.
The fine structural localization of acetylcholinesterase activity in the rat parotid and sublingual glands
Authors: Bogart Bruce Ian 
Published: February 2005

AbstractThe fine structural localization of acetylcholinesterase activity was studied in the rat parotid and sublingual glands. In both glands, reaction product was found in association with the axolemmae of stromal axons invested by Schwann cells and between the contact with effector cells. In the sublingual gland, reaction product was also found in association with surface vesicles and pits and the rough endoplasmic reticulum of myoepithelial cells.
Autoradioraphic studies on 14C‐leucine incorporation into motor neurons of the spinal cord of X‐irradiated mice
Authors: Olkowski Zbigniew 
Published: February 2005

AbstractThe incorporation of 14C‐leucine into the cytoplasm and nuclei of the motor neurons in the spinal cords of control mice and of mice given total‐body X‐irradiation was studied with the use of autoradiography. A decrease in isotope incorporation into the cell cytoplasm of the motor neurons in the spinal cords of irradiated mice was observed. The incorporation of 14C‐leucine into the nuclei of the motor neurons of spinal cords of irradiated animals was increased significantly as compared to the appropriate control values.