bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hair growth in skin grafts placed on hairless mice
Authors: Argyris Thomas S. , Argyris Bertie F. 
Published: February 2005

AbstractThe purpose of this study is to investigate the possibility that hair growth is triggered by the loss of a specific hair follicle inhibitor.If the loss of an inhibitor is a sufficient cue for the triggering of hair growth, then hair follicles in skin grafts placed on hairless mice should remain in the growth phase of the hair growth cycle, and never enter the resting phase. This would be expected because hairless skin has no hair follicles, and therefore presumably produces no hair follicle inhibitor itself. Thus, no build‐up of a hair follicle inhibitor within the graft should occur.Female hairless mice (HRS/J) approximately 60 days of age received skin grafts from haired female litteremates. These skin grafts took well and remained healthy throughout the period of investigation, which ranged from 240–380 days.The hair follicles of the grafts undergo cycles of growth and rest. They may remain in the resting phase for as long as two to three months. Therefore, hair follicles of grafts placed on the backs of the hairless mice do not remain permanently in the growth phase of the hair cycle.Additional experiments help rule out the possibility that (1) the lack of continuous hair growth of the hair follicles in the grafts is due to the scar preventing the diffusion of inhibitors from the graft into the host skin, and (2) that the hair follicle remnants in the host hairless skin produce a hair follicle inhibitor in sufficient concentration so that the hair follicles of the graft enter the resting phase.
The fine structure of secretory granules in submandibular glands of the rat during early postnatal development
Authors: Kim S. K. , Han S. S. , Nasjleti C. E. 
Published: February 2005

AbstractThe secretory end‐pieces of the submandibular gland of rats during the first week of postnatal development are studied with regard to the fine structure of the secretion granules in these end‐pieces. The terminal ends of the secretory ducts during this period consist of two types of cells; one cell is an acinar‐type and the other is a duct‐type found in the gland of adult rats. The secretion granules of the acinar‐type cells are similar in appearance to those of the acinar cells in the gland of adult rats, and the structure of these granules remains the same throughout the week. However, granules widely different in appearance are present in the duct‐type cells, and their structure varies in different cells as well as within a single cell at different stages of development. These granules contain unusual substructures which are not found in the secretion granules of adult rats, suggesting that the granules are transitory. Granules containing short tubular profiles are predominant in the gland of one day‐old rats. A large number of granules in three day‐old rats contain elongated tubules. More granules of widely different substructures are present in the gland of seven day‐old rats than in the gland of younger rats. The matrix of the granules in seven day‐old rats is of higher density than that of the granules in younger rats. In the dense matrix of these granules, less dense tubules form fingerprint‐like or somewhat more irregular patterns.
The connections of the intra‐osseous segment of the facial nerve in baboon (Papio sp.)
Authors: Vidić Branislav 
Published: February 2005

AbstractTo supply some additional data about the intra‐osseous connections of the seventh nerve in a potentially available experimental animal, the baboon, 16 neuromuscular complexes (otic ganglion, nerve which results from the junction between the lesser petrosal nerve and the and the communicating branch, lesser petrosal nerve, communicating branch, initial part of the greater petrosal nerve, all three intra‐osseous parts of the facial nerve, stapedius muscle, auricular branch of the vagus) were macroscopically evaluated with the aid of a microdissecting scope, and removed in toto. Two dissections were achieved only partially. Each neuromuscular complex was fixed in 5% formalin, dehydrated, embedded in paraffin, sectioned serially at 10 to 15 μ, and either stained with Luxol Fast Blue or impregnated by Bodian's silver technique. In all specimens considered, the auricular branch of the vagus, before it joined the descending intra‐osseous part of the facial nerve, gave off an ascending bundle. This bundle sent a few ramifications to the stapedius muscle and finally mixed with axones in the intra‐osseous segment of the seventh nerve close to the second facial genu. The fibers in the ascending bundle were predominately myelinated with a diameter varying from 1.7 μ to 9.9 μ. The communicating branch proper separated from the fibers of the second intra‐osseous part of the facial nerve, and continued anteriorly through the sheath toward the geniculate ganglion. From there, the branch as an isolated bundle extended further anteriorly to reach the otic ganglion, after it joined the lesser petrosal nerve. The number of fibers in the communicating branch ranged from 50 to 580, and the diameter of myelinated fibers varied between 1.7 and 4.4 μ. Numerous ganglion cells, presumably of the autonomic type, found in the communicating branch, in the lesser petrosal nerve, and occasionally in the second intra‐osseous part of the facial nerve resembled by their form and diameter the ganglion cells in the otic ganglion.
The non‐fibrous nature of the von Korff fibres in developing dentine. A light and electron microscope study
Authors: Cate A. R. Ten , Melcher A. H. , Pudy G. , Wagner D. 
Published: February 2005

AbstractFirst molar tooth germs were dissected from one‐ and seven‐day‐old mice, fixed in gluteraldehyde and impregnated in bulk using silver nitrate for the demonstration of reticulin. After impregnation the tooth germs were embdded in Epon, and thin sections cut for examination with both the light and electron microscope. Control tooth germs were prepared similarly, but were not impregnated with silver. Light microscopic examination showed the classical picture of von Korff fibres. These were associated with the formation of mantle dentine. von Korff fibres were not found associated with forming circumpulpal dentine. Examination of successive sections with the electron microscope showed silver particles between the widely separated, newly differentiated, odontoblasts. In forming circumpulpal dentine, the odontoblasts were closely aligned and no silver particles were found in the now narrowed extracellular spaces. Examination of control sections revealed that the extracellular compartment between the newly differentiated odontoblasts consisted of ground substance and a few sparse collagen fibrils which were too small to be resolved with the light microscope. It is considered that the “von Korff fibres” seen with the light microscope represent silver impregnation of the extracellular material, which is mainly ground substance, in the continuum between the widely separated odontoblasts.
Intracristal helices in salivary gland mitochondria
Authors: Hand Arthur R. 
Published: February 2005

AbstractHelical filaments have been found within dilated intracristal spaces of normal rat salivary gland mitochondria. Filament diameter measured 35–45 Å, and the helix diameter and pitch were 140–155 Å. They were found in as many as 25% of the mitochondria of acinar and intercalated duct cells. Helices were not found in mitochondria of the striated duct cells.
Tissue cholesterol preservation: Solubility of cholesterol digitonide in ethanol
Authors: Sterzing Peter R. , Scaletti Joseph V. , Napolitano Leonard M. 
Published: February 2005

AbstractThe solubility of purified cholesterol digitonide in absolute and aqueous ethanols was investigated. The results indicate that preservation of cholesterol (or other 3‐B‐hydroxysterols) in tissues prepared for electron and light microscopy by digitonin‐containing fixatives may not be quantitative when ethanol and, in particular, absolute ethanol, is used for dehydration.
The histophysiology of rat plantar sweat glands
Authors: Munger Bryce L. , Brusilow Saul W. 
Published: February 2005

AbstractThe plantar sweat glands of the rat have been studied by light and electron microscopy. These glands differ from conventional eccrine sweat glands of man, other primates, and cats in that the secretory segment contains only one type of secretory cell. This cell is characterized by a relatively nondescript cytoplasm containing numerous vesicles, extensive interdigitations of adjacent plasma membranes and small microvilli projecting into the lumen. In the resting gland, two types of cells can be distinguished on the basis of mitochondrial morphology. Some cells contain mitochondria in condensed configurations, and others contain mitochondria in the more orthodox configuration. Following stimulation, these differences are not pronounced; and the condensed mitochondria have evidently changed into more orthodox mitochondria in appearance. No distinct cytologic pathway for secretion could be defined, correlated with the most unusual ionic composition of the sweat in this animal (very high levels of potassium). The sweat glands of the rat foot pad then are unique as compared with other cutaneous glands both in their cytologic appearance and in the chemical composition of the sweat they elaborate.
Ultrastructural differentiation of the endodermal cells of the yolk sac of the bat, Tadarida brasiliensis cynocephala
Authors: Stephens R. J. , Easterbrook N. 
Published: February 2005

AbstractIn Tadarida, the endodermal cells that form the yolk sac originally delaminate from the inner cell mass and proliferate to form a complete lining of the trophoblastic vesicle, creating a bilaminar omphalopleure. These cells remain squamous until the splanchnic mesoderm migrates in between the two layers of the omphalopleure, at which time they begin to hypertrophy. The current study is an analysis of the cytological changes that accompany this hypertrophy as well as additional changes that occur throughout the remainder of the gestation period. Among the early changes are: (1) the formation of numerous microvilli along the apical surface of the cells, (2) the appearance of coated vesicles, also along the apical plasma membrane, (3) the establishment of a system of absorption tubules in the apical cytoplasm, (4) an increase in mitochondria, and (5) the appearance of glycogen within the channels of the membranous organelle.A wave of hematopoietic activity follows the migration of splanchnic mesoderm around the trophoblastic vesicle, and at this time the erythroblasts and embryonic erythrocytes can be seen in a close relationship with the endodermal cells.Subsequent changes include the enlargement of the membranous organelle and the appearance of a paracrystalline membranous structure. In addition, the endodermal cells store large quantities of lipid and glycogen that are substantially depleted just before birth.
The common cardinal veins in the chick embryo: Their origin and development as studied by radioautographic mapping
Authors: Rosenquist Glenn C. 
Published: February 2005

AbstractThe origin of the common cardinal veins (CCVs) in the chick embryo was traced by radioautographic mapping of the movements of tritiated thymidine‐labeled grafts excised from head process to three somite stage embryos and transplanted to the endoderm‐mesoderm layer of similarly staged recipient embryos.At the head process stage the CCV cells are migrating anteriorly and laterally from the streak in the lateral plate, posterolateral to the cells which will form the pulmonary veins and aortic arches, posterior to the cells destined for the ventricular septum, and dorsal to the liver mesoderm cells. At the 15–17 somite stage, the CCV cells are in the somatic mesoderm of the lateral mesocardium, where an anastomosis between the CCVs and heart establishes channels needed for the efficient return of blood from the various embryonic venous tributaries. This investigation suggests that during the stages studied, the cells which will form the anterior portion of each CCV are positioned anterior to the cells which will form the posterior portion of each CCV.
Arterial supply of the cervical spinal cord (with special reference to the radicular arteries)
Authors: Chakravorty Binoy G. 
Published: February 2005

AbstractArterial supply of the cervical spinal cord has been discussed with special reference to the radicular arteries. Thirty‐one human spinal cords have been studied with postmortem positive pressure injection techniques using coloured, and radio‐opaque media. Observations concluded that radicular arteries were main sources of supply to spinal cord except at the highest segments (C1C2C3), where intracranial vertebral branches contribute. Average number of significant radicular arteries is two or three, in two‐thirds of the specimens only one was present. These feeding radicular arteries usually enter into the spinal canal through the intervertebral foramina accompanying C4C5C6 nerve roots to join the anterior and posterior spinal arteries. Anterior, and posterior spinal arteries are probably of segmental origin, and there is only a sparse anastomosis between them. The common radicular artery divides into an anterior, and a posterior branch of which one predominates in size. Cervical radicular arteries may originate from subclavian branches other than vertebral, of these ascending cervical branch of thyrocervical trunk is most important. A terminal zone probably exists at highest thoracic segments where craniocervical, and thoracic radicular flows meet. The filling of the anterior spinal trunk in the cervical region depends on the availability of at least one major anterior radicular artery. Interruption of radicular supply may be precipitated by trauma, spondylosis and other lesions resulting into ischaemia, and myelopathy; the risk is greater if there is only one radicular artery which is involved.
The development of the periodontium. A transplantation and autoradiographic study
Authors: Cate A. R. Ten , Mills C. , Solomon G. 
Published: February 2005

AbstractFirst molar tooth germs were dissected from one‐day‐old mice; placed for one hour in McCoy's medium containing 10 μc tritiated thymidine and transplanted subcutaneously into young adult animals of the same strain. Seven, 14, 21 and 28 days after implantation the host animals were sacrificed and the transplants harvested. The transplants were then serially sectioned and autoradiographs prepared. Control sections were prepared of first molar tooth germs in situ, after dissection from the jaws and after labelling with tritiated thymidine. Forty‐nine of the 115 transplanted tooth germs continued development with the formation of enamel, dentine, cement, periodontal ligament and bone. In some instances the transplanted tooth germs “erupted” through the skin with the establishment of an epithelial attachment. Examination of control sections showed that the transplants consisted of dental organ, dental papilla and a layer of ectomesenchymal cells continuous with the dental papilla and investing the dental organ. Examination of autoradiographs of the transplants showed labelling of cementoblasts and periodontal ligament fibroblasts, thereby establishing their origin from the ectomesenchymal cells investing the tooth germ.
Transport and barrier function in the chorioallantoic placenta of the bat, Myotis lucifugus
Authors: Enders Allen C. , Wimsatt William A. 
Published: February 2005

AbstractThe chorioallantoic placenta of the bat (Myotis lucifugus) is hemodichorial and has an ectoplasmic layer and an intrasyncytial lamina interposed between the maternal blood space and the underlying endoplasmic portion of the syncytial trophoblast. The barrier and/or transport function of the trophoblast of this species was investigated. When Thorotrast was injected into the maternal vascular system, only small amounts appeared in the trophoblast, and it could not be demonstrated deep to the syncytial trophoblast.Injected peroxidase and ferritin were both rapidly taken up by the trophoblast, these tracers being found in coated vesicles and tubules, in multivesicular bodies, and in dense bodies. Peroxidase was transported across the trophoblast and could be found in macrophages in the fetal connective tissue and in vesicles in the fetal endothelium. Since ferritin is present in the cytotrophoblast, macrophages and fetal endothelium in uninjected as well as injected animals, the exogenous material could not be followed beyond the syncytium. In addition to demonstrating the cytological pathway by which absorbed proteins cross the trophoblast of the chorioallantoic placenta of the bat, the results of this study suggest that the labyrinth in this species should be considered a possible route for passage of endogenous proteins to the fetus.
Neuroglial population in the spinal white matter of neonatal and early postnatal rats: An autoradiographic study of numbers of neuroglia and changes in their proliferative activity
Authors: Gilmore Shirley Ann 
Published: February 2005

AbstractThe temporal pattern of increase in number of neuroglia in spinal cord white matter and the amount of multiplication in situ of these cells were studied in rats ranging from less than 12 hours following birth to 30 days of age. Autoradiographs of sections from animals killed four hours after injection of tritiated thymidine were studied; counts of the total neuroglial population and of the number of labeled neuroglia were made in the white matter of each half of the cord (hemisection). During the first two weeks following birth, the number of neuroglia per hemisection increased six times; thereafter, the population appeared to be stable. The increases in number of labeled neuroglia appeared to parallel the rise in total population, particularly during the period of greatest population increase, i.e., days 7 through 12. After 12 days, when the total population stabilized, there was a marked and rapid decrease in the number of labeled cells. The walls of the central canal were examined in view of the role this area plays in the initial development of the nervous system. In rats killed during the first 14 days postnatally, the dorsal and ventral walls were incomplete; however, numerous, unidentified cells adjacent to these walls were oriented as if entering the dorsal median septum and the ventral median sulcus. By 22 days the central canal area had more of its adult appearance.
The structure of developing bone marrow sinuses in extramedullary autotransplant of the marrow in rats
Authors: Tavassoli Mehdi , Weiss Leon 
Published: February 2005

AbstractThe structure of the developing sinuses of the bone marrow was studied in extramedullary autotransplants of the marrow in rats just before the onset of hemopoiesis. Sinuses are highly branching channels with walls consisting of a single layer of endothelium. The wall thickness varies considerably but larger sinuses generally have a thinner wall. Endothelial cells may overlap and interdigitate displaying junctional densities. Abrupt thinning of endothelium was observed in some areas but no apertures were noted. The endothelium is sometimes surrounded by collagen, but no basement membrane is present. Twenty‐four percent of the endothelial surface is covered by pericytes and often rarified cytoplasmic spurs extend into perisinus areas. Microfilaments were seen under the cell membrane of pericytes. Medium‐sized lymphocytes are frequently seen in the sinal lumen and intersinal tissue and they may constitute hemopoietic stem cells.
Morphological studies of the altered pulps of the New Zealand white rabbit after resection of the inferior alveolar nerve and/or the superior cervical ganglion
Authors: Avery J. K. , Strachan D. S. , Corpron R. E. , Cox C. F. 
Published: February 2005

AbstractThis study was carried out to determine the effects of denervation of the pulp organs of teeth, particularly on the odontoblasts and their processes. Therefore, resection of the inferior alveolar, cervical sympathetic, or a combination of both types of nerves supplying the mandibular incisor teeth of New Zealand white rabbits was performed and the results compared to adjacent, unaltered teeth. Neural stains were used to evaluate the presence or absence of nerve elements, while histochemical and titrametric methods were employed to determine the presence, location and concentration of cholinesterase enzymes in these teeth. Dilation of blood vessels was noted after cervical sympathetic resection and larger nerve trunks as well as peripherally located fine fibers were absent in the pulps following inferior alveolar nerve resection. Further, irregular dentin formation and associated small openings in the tips of the teeth were observed after nerve resection. Titrametric analysis indicated a significant decrease in the concentration of cholinesterase in the pulp organ of incisors 15–19 days after resection of either the inferior alveolar nerve or both inferior alveolar and cervical sympathetic nerves. Only a slight decrease in the concentration of cholinesterase was noted after removal of the cervical sympathetic nerve alone. Histochemical results confirmed a decrease in cholinesterase after resection of the inferior alveolar, cervical sympathetic or both nerves. The concentration of the oxidative enzyme, succinic dehydrogenase, however, increased after all three types of nerve resection. This increase was apparent particularly in the odontoblastic cells underlying the predentin.
The origin of osteoclasts in estrogen‐stimulated bone resorption of the pubic symphysis of the mouse
Authors: Corwin James A. , Morehead James R. 
Published: February 2005

AbstractFour‐week‐old female mice were injected with estradiol, and the following day received intraperitoneally one μC/gm body weight of thymidine‐methyl 3H. At various intervals following the injection of thymidine‐3H, pairs of mice were sacrificed, the pubic symphyses excised and prepared for radioautographs of transverse sections. Examination of the radioautographs revealed that the highest percentage of labeled cells was to be found in the osteoprogenitor cell population at all time intervals examined. The number of osteoclasts and the percentage of labeled osteoclasts rose progressively. The percentage of labeled osteoblasts rose and then fell, but was at all times much less than that of the osteoprogenitor cell population.Since the osteoprogenitor cell population was the only one in which the percentage of labeled cells was high enough to account for the rise in the percentage of labeled osteoclasts, the conclusion was drawn that the labeled osteoclasts arose from the labeled osteoprogenitor cells.In support of the above conclusion, and in keeping with the theory that the osteoprogenitor cell undergoes “differential” mitosis, one daughter cell going on to become an osteoclast or an osteoblast and one daughter cell remaining in the osteoprogenitor cell population, the number of silver grains over the labeled osteoclast nuclei was observed to be roughly one‐half that over the labeled osteoprogenitor cell nuclei.