bluuebunny/crossref_metadata_2025_split huggingface dataset:
The initial appearance of ossification in staged human embryos
Authors: O'Rahilly Ronan , Gardner Ernest 
Published: February 2005

AbstractSerial sections of 36 embryos aged six to eight postovulatory weeks (12 to 31 mm C. R. length) were examined. The clavicle and the mandible began to ossify during stage 18, 19, or 20, the clavicle (at least frequently) by means of two centers. The maxilla followed rapidly (stages 19, 20). The premaxilla was in continuity with the maxilla proper, either as a mesenchymal condensation or as an ossific area (stages 20, 21). The next elements to commence ossification were the humerus (stages 21, 22), the radius (stages 21, 23), and the femur, tibia, and ulna (stages 22, 23). By stage 23 the following were also undergoing ossification in at least some cases: interparietal, supra‐occipital, anterior process of the malleus, the squamous temporal, palatine, medial pterygoid plate, zygomatic, frontal, vomer, scapula, and distal phalanges of the hand. Cellular invasion was found in the clavicle and in the bone collars of the radius, ulna, and femur at eight postovulatory weeks. The cartilages of the first pharyngeal arches (chondrifying at stages 18, 19) approached the median plane (stage 20) but did not fuse in the embryonic period proper; their cartilaginous tissue underwent localized hypertrophy by stage 23, but endochondral ossification did not occur until the fetal period.
The cellular origins of corticotropin and melanotropin as revealed by immunochemical staining
Authors: Baker Burton L. , Drummond Thérése 
Published: February 2005

AbstractThe cellular origins of corticotropin and melanotropin were studied by observing the response of the rat hypophysis to adrenalectomy and cortisol administration when stained immunochemically with peroxidase‐labeled antibody following application of antiserums to β1–24‐corticotropin, βP17–39‐corticotropin, human β‐melanotropin, and α‐melanotropin. The presence of corticotropin in the pars intermedia is indicated since this lobe, in addition to corticotropic cells of the pars distalis, stained with antiserum to βP17–39‐corticotropin. However, the concentration of corticotropin is less in the pars intermedia than in corticotropic cells since at higher dilutions of antiserum the latter cells stained intensely while the pars intermedia was unstained. Also, corticotropic cells exhibited striking hypertrophy after adrenalectomy and regression after cortisol administration, while morphological and tinctorial properties of the pars intermedia were minimally altered. These observations suggest that the pars distalis is primarily responsible for supplying the corticotropin required to meet the changing requirements of the body.With antiserum to human β‐melanotropin, the pars intermedia stained intensely. Since the antiserum was ineffective after absorption the staining reaction appears to be specific for β‐melanotropin. Except for a rare cell, the pars distalis did not stain. Thus β‐melanotropin is restricted primarily to the pars intermedia.
Morphogenetic studies of the rabbit. XLII. Growth gradients, epigenetic variants, and function
Authors: Sawin P. B. , Hamlet Martha 
Published: February 2005

AbstractComparison of the effects of the Da gene upon the spheno‐occipital synchondrosis in rabbits of strain DA and unrelated strain IIIDa has made possible study of the relative effects of Da growth retardation and strain differences of primary and secondary growth gradients and their interaction. When Da is absent and parental border shift dosages (which portray the localization and magnitude of thoracic and lumbar gradients) are most anterior, synchondrosis fusion is minimal in both strains. Presence of Da in either Da/+ or Da/Da genotype significantly increases the penetrance and expression of fusion in both strains. Fusion tends to be additively increased when parental thoracolumbar and lumbosacral borders are shifted anteriorly, and antagonistically decreased when they are replaced by posterior border shifts. The interaction of these two (gene and genome) influences results in patterns of continuous distribution involving from two to five classes. Penetrance of fusion is outstandingly affected by Da whereas expressivity obviously is more specifically associated with vertebral border shifts. This differentiates their associations with primary and secondary gradients respectively. The study shows how such epigenetic variants and specific gene induced localized retardations could be used in genetic analyses of basic growth processes. Studied developmentally in time and relation to function, they could establish firm grounds for prediction and control of abnormal development.
Myocardial cell diameters in primate hearts
Authors: Truex Raymond C. 
Published: February 2005

AbstractThis light microscope study on the cell diameters of six myocardial structures was based 15 primate hearts. One hundred cell measurements were made of each cell category in each of five speciments of three primate species (monkey, baboon, man). Mean values of cell diameter, range and the standard error of each group of measurements are presented in graph form. The coefficients of variation between the cells in each of the five hearts of each species are presented. Microscopically the small cells of the SA and AV nodes constitute a more uniform population, while the atrium, AV bundle and left bundle branch have a heterogeneous admixture of large and small cells. Left ventricles of the human and baboon hearts had more uniform cell populations than did the left ventricle of the monkey. Representative examples of the more heterogeneous areas are demonstrated photographically. The sources of error, importance of several cardiac junction sites, significance of cell diameter in cardiac hypertrophy and the potential relationship between cell size and cardiac conduction velocities are presented.
Bidirectionality in the tongue processes of the oligodendroglial cell investment of axons in the albino rat
Authors: Stempak Jerome G. , Knobler Robert L. 
Published: February 2005

AbstractSerial sections from the lumbar spinal cord of 5‐day old female albino rats were examined by electron microscopy. A change in direction of the inner and outer processes of the oligodendroglial cell investment of an axon within an internode was observed in two ribbons. The shorter of the two ribbons is described in this report.
Effect of vinblastine sulfate on the fine structure of cells of the rat renal corpuscle
Authors: Tyson Greta E. , Bulger Ruth Ellen 
Published: February 2005

AbstractVinblastine sulfate was administered intravenously to adult rats chiefly to study the effect of microtubule loss on the cell shape of renal podo‐cytes. After treatment which resulted in a nearly complete absence of normalsized microtubules (260 Å diameter) in podocytes, there was no evidence that any alteration in cell shape accompanied the disappearance of these organelles. Unlike podocytes, blood platelets did undergo a change in shape with exposure to the drug. After treatment, platelets seen within glomerular capillaries were more spherical and rarely contained microtubules.Intracytoplasmic paracrystalline inclusions characteristic of vinblastine treatment were observed in visceral and parietal cells of Bowman's capsule, glomerular endothelial cells, blood platelets, mesangial cells, interstitial fibroblasts, mononuclear leukocytes, a granulated juxtaglomerular cell, and cells of the proximal and distal convoluted tubules. Unusually large microtubules, with an approximate diameter of 450 Å, were also seen in a variety of cell types after vinblastine treatment. In favorably oriented cross‐sectional profiles, 12–13 subunits were discernible within the wall of these large microtubules.
Vitality of chondrocytes in the mandibular condyle as revealed by collagen formation. An autoradiographic study with 3H‐proline
Authors: Silbermann Michael , Frommer Jack 
Published: February 2005

AbstractHistological and autoradiographic studies using 3H‐proline indicate that cartilaginous tissue in the mandibular condyle maintains morphologic and metabolic characteristics of an embryonic type of tissue. Cartilage cells in the condyle lack the specific arrangement and cellular homogeneity characteristic of more differentiated endochondral growth sites. Through dedifferentiation many chondrocytes in the mandibular condyle appear to outlive the hypoxic conditions that are reported to prevail within the mineralizing zone. Chondrocytes in this zone reveal only a minimal amount of 3H‐proline uptake in comparison with the cells in the chondroblastic and premineralizing zones. The dedifferentiated chondrocytes appear to redifferentiate into more specialized cells, possibly osteoprogenitor cells, as they reveal a significant increase in 3H‐proline incorporation in the vicinity of the ossifying front. These observations on proline metabolism support the concept that calcification in the condylar cartilage is not necessarily accompanied by degeneration and death of the chondrocytes.
The arteries of the pancreas of the dog. An injection–corrosion and microangiographic study
Authors: Cadete‐Leite A. 
Published: February 2005

AbstractThe ramification of the pancreatic arteries, including the lobular vessels, was studied in 36 mongrel dogs by means of plastic injection and corrosion, as well as microangiography.The left pancreatic lobe receives the left cranial pancreatic artery and other smaller branches from the splenic artery, and two to four twigs from the gastroduodenal artery. In addition, it receives very often a branch from the common hepatic artery. Branches arising from the cranial mesenteric artery and from the first jejunal artery may also be found. The right cranial pancreatic artery and the right gastroepiploic artery give branches to the pancreatic angle. The arteries to the right pancreatic lobe arise from the cranial and from the caudal pancreaticoduodenal arteries.The interlobular arteries give origin to the intralobular arteries. The penetration and the distribution of the latter vessels differ in lobules of different shape. The intralobular course may be straight or curved. Branches arise generally at acute angles, forming Y or fork‐like patterns, ending into bundles of arterioles.
Scanning electron microscope studies of some lizard basilar papillae
Authors: Miller Malcolm R. 
Published: February 2005

AbstractThe papillae basilares of eight species of lizards representing four different families were studied by scanning electron microscopy.The papilla of Eublepharis macularius (Gekkota; Eublepharidae) has a midaxial area devoid of hair cells separating anterior and posterior groups of hair cells, two types of tectorial membrane modifications, bidirectionality of each of the anterior and posterior groups of ventral hair cells, and unidirectionality of the dorsal hair cells. The papilla of Coleonyx variegatus (Gekkota; Eublepharidae) is essentially similar to that of Eublepharis, but shows anterior displacement of the axial hiatus and a considerable decrease in the number of hair cells in the dorsal part of the postaxial region. The papilla of Ameiva ameiva (Teiidae) has a dorsal enlargement almost constricted from the remaining portion of the papilla and the greater number (87%) of the hair cells oriented posteriorly. Tupinambis teguixin (Teiidae) exhibits multidirectional hair cell orientation in the expanded dorsal area, bidirectionality in the narrower central segment, and unidirectionality toward the ventral end of the papilla.Gerrhonotus multicarinatus (Anguidae) shows a ventral expansion covered by a thick tectorial plate overlying short‐ciliated unidirectionally oriented hair cells and a longer dorsal segment with long‐ciliated bidirectionally oriented hair cells. The papillae of Iguana iguana, Crotaphytus collaris, and Basiliscus basiliscus (Iguanidea) have middle segments of short‐ciliated hair cells covered by a specialized tectorial plate and dorsal and ventral segments consisting of longciliated bidirectionally oriented hair cells. Basiliscus is divergent in lacking a part of the ventral long‐ciliated hair cell segment.
Fine structure of the differentiating acini in submandibular glands of isoproterenoltreted rats
Authors: Bressler Robert S. 
Published: February 2005

AbstractChronic treatment with isoproterenol, a β‐adrenergic drug, accelerates the postnatal differentiation of the rat submandibular gland. This report compares the ultrastructure of submandibular glands of acute and chronically treated, 2, 11 and 17‐day‐old rats with that of controls. In all cases a greater number of acinar cells were found in the treated glands. The correlation noted between changes in the nature of the contents of the condensing vaculoes and Golgi apparatus of some proacinar cells and the formation of secretory granules intermediate in appearance between those of proacinar and acinar cells, support the hypothesis that proacinar cells are the precursors of acinar cells in the young rat. Differences in the morphology of secretory granules in acinar cells of treated and control animals are described. It is concluded that precocious differentiation of the submandibular gland may be induced by the administration of isoproterenol as early as the first day of postnatal life, that proacinar cells become recognized as acinar cells following a change in the nature of their secretory product, and that the secretory material produced by acinar cells in the treated animals is not identical to that of the controls.
Effects of blinding, olfactory bulbectomy, and pinealectomy on prolactin and growth hormone cells of the rat, with special reference to ultrastructure
Authors: Shiino Masataka , Arimura Akira , Rennels Edward G. 
Published: February 2005

AbstractThe effects of combined blinding and olfactory bulbectomy alone or with pinealectomy on body growth, and pituitary and serum levels of growth hormone and prolactin were examined in young female rats. The animals were 23–24 days old at the time of the operations, and they were sacrificed 52 days later. Blind, anosmic rats had elevated serum and depressed pituitary stores of prolactin. The blind, anosmic rats which were also pinealectomized showed prolactin levels which were intermediate between those of the blind, anosmic and sham control animals. On the other hand, combined blindness and anosmia decreased serum growth hormone levels and again pinealectomy prevented this effect. The observed changes in the ultrastructure of prolactin and growth hormone cells were well correlated with these alterations in hormone levels.
Phagocytosis in the light‐damaged albino rat eye: Light and electron microscopic study
Authors: O'Steen W. Keith , Karcioglu Zeynel A. 
Published: February 2005

AbstractRetinal photoreceptor degeneration was induced by exposing albino rats to fluorescent illumination at elevated environmental temperatures. Fine carbon particles were injected intravenously or directly into the vitreous body or anterior chamber of the eye. The resulting pattern of invasion, migration, and egression of carbon‐filled phagocytes in eyes with degenerated retinas was reconstructed from a time sequence series of light and electron microscopic tissue sections. Retinal debris, such as damaged photoreceptor outer segments and carbon particles, was most frequently removed by two populations of cells possessing phagocytic properties: mononuclear cells of vascular origin and pigment epithelial cells. After retinal damage, mononuclear cells appeared first in the vitreous body and later, in time sequence, progressively deeper in the inner plexiform layer and out to the bipolar nuclear layer, where they were seen within, or partially within, retinal capillaries. After intravenous carbon injection, however, marked phagocytes were not seen in the retina. Carbon‐filled phagocytic cells were observed in the choroidal connective tissue and blood vessels after intravenous injection, but not after intravitreal injections of carbon. Therefore, retinal phagocytes did not appear to leave the eye through the choroidal circulation. Pigment epithelial cells proliferated by mitotic activity, occurred as single cells separated from Bruch's membrane, and were seen among the degenerated outer segments. After direct exposure to carbon particles, pigment cell phagosomes contained both carbon and lamellated discs of degenerated outer segments. Whether these cells exited from the eye through retinal capillaries or returned to Bruch's membrane to reestablish continuity in the pigment epithelium could not be determined.
Development of the zona pellucida in the rat oocyte
Authors: Kang Yuan‐Hsu 
Published: February 2005

AbstractOvaries of weanling and juvenile rats were studied by electron microscopic and cytochemical techniques, with particular reference to the role of the Golgi complex in the formation of the zona pellucida. The zona pellucida type of material first appears in the perivitelline space at the stage when the oocyte acquires a single layer of flattened and cuboidal granulosa cells, and is completely formed when the granulosa cells attain a cuboidal shape. The intimate association of the Golgi complex with the oocyte plasmalemma and the presence of mucopolysaccharide in its saccules and vesicles suggests that the Golgi complex of the oocyte plays an important role in the synthesis of the zona pellucida. The zona pellucida of the rat egg consists of a single layer of acid mucopolysaccharide which is structurally distinguishable from the liquor folliculi. Formation of the primary liquor folliculi is attributed to the Golgi complexes in granulosa cells.
A scanning electron microscopic study of the nephron
Authors: Andrews Peter M. , Porter Keith R. 
Published: February 2005

AbstractScanning electron microscopy was used to study the ultrastructural morphology of the nephron. Material for observation was taken from rat kidneys which were fixed by vascular perfusion. Different techniques for splitting open the kidney, combined with stereoscopic viewing, provided many instructive views of nephron morphology. In addition, scanning electron microscopy revealed a number of new features including (1) the complex organization and structure of kidney podocytes; (2) the distribution of endothelial pores and the presence of endothelial microprojections and branching endothelial thickenings; and (3) the presence, distribution and morphology of microprojections and cilia on the luminal surfaces of Bowman's capsule and the uriniferous tubules.
A cluster of supraependymal neurons located within the infundibular recess of the rat third ventricle
Authors: Paull Willis K. , Scott David E. , Boldosser W. G. 
Published: February 2005

AbstractA nidus of supraependymal cells was located within the infundibular recess of a rat's third ventricle. Upon transmission electron microscopic analysis, these cells were clearly identified as neurons. Neuronal processes, as well as end‐terminals that contained dense‐core and clear synaptic‐like vesicles, were also observed coursing around these cells. It is suggested that some of the supraependymal cells that have been observed in previous scanning electron microscopic studies could be neurons similar to those described here.
Annulate lamellae in hepatic and pancreatic beta cells of the chick embryo
Authors: Benzo Camillo A. 
Published: February 2005

AbstractThis study is concerned with the finding of cytoplasmic annulate lamellae in normally developing avian somatic tissues. Annulate lamellae were observed in hepatic parenchymal and pancreatic beta cells of the chick embryo on days five and eleven, respectively, of egg incubation. The presence of this cytoplasmic membrane system in normal embryonic tissues supports the view that annulate lamellae may represent normally occurring, transitory organelles common to virtually all cells during early embryonic differentiation.
Vinblastine‐induced aggregates of smooth endoplasmic reticulum in proximal tubular cells of rat kidney
Authors: Tyson Greta E. , Bulger Ruth Ellen 
Published: February 2005

AbstractVinblastine sulfate was given to adult rats by two tail‐vein injections. After a total treatment time of five hours, kidney cortex was fixed and prepared for examination by routine transmission electron microscopy. Cells of proximal convoluted tubules from treated animals were found to contain focal aggregates of smooth endoplasmic reticulum. Such aggregates were not normally present in cells of control animals. The smooth membranes of these aggregates bear some resemblance to phenobarbital‐induced proliferations of smooth endoplasmic reticulum described in liver cells by many previous investigators, and the suggestion is made that the aggregates described here may reflect a vinblastine‐induced increase within proximal tubule cells of enzymes which function in drug metabolism. That molecules of vinblastine actually entered proximal tubule cells was evidenced by the fact that cytoplasmic microtubules were greatly reduced in number and paracrystals of microtubular protein were occasionally observed.
An ultrastructural comparison of the uptake and transport of horseradish peroxidase by the rat visceral yolk‐sac placenta during mid‐ and late gestation
Authors: Seibel Werner 
Published: February 2005

AbstractHorseradish peroxidase was used to explore electron microscopically the uptake and transport of protein by the rat visceral yolk sac at 2 minutes, 6 hours, and 12 hours following a single intravenous injection into pregnant rats on day 12 and day 21.5 of gestation.On both days, the visceral endoderm absorbed peroxidase via micropinocytosis at 2 min postinjection, but not at the 6 and 12 hr intervals. At the latter two postinjection intervals on day 12, peroxidase was localized mainly at two sites, i.e., within intraepithelial supranuclear storage vacuoles, and within the vitelline endothelium deep to the visceral endoderm. On day 21.5 at 6 and 12 hr postinjection, peroxidase was localized in supranuclear storage vacuoles, though most of it was within tubular structures and small vacuoles in the paranuclear and infranuclear cytoplasm of the endoderm. Many dense vacuoles were in close anatomical relationship with the basal cell membrane. Deep to the endoderm a few macrophages were actively engulfing peroxidase, but reaction product was rarely found in the fenestrated vitelline endothelium.The results presented differ from the previous physiological and anatomical transport studies of the visceral yolk sac in that protein (peroxidase) transport was observed deep to the endoderm during both mid‐ and late gestation.
Hydrolytic enzyme activity during endochondral ossification of secondary cartilage
Authors: Silbermann Michael , Frommer Jack 
Published: February 2005

AbstractReactions for hydrolytic enzymes such as aminopeptidase, β‐glucuronidase, N‐acetyl‐β‐glucosaminidase, arylsulfatase and non‐specific esterases indicated various degrees of activity within the chondrocytes of the young mandibular condyle. Most of the reaction products of the above enzymes appeared as discrete granules, which might indicate a lysosomal origin. The most intense activity of these enzymes was observed within chondroblasts and premineralizing hypertrophic chondrocytes. However, chondrocytes within the mineralizing zone also appeared synthetically active. The latter cells, as well as those at the adjacent ossification front, revealed some activity by a majority of the enzymes tested. This could indicate that some metabolic functions, although reduced in degree, continue in the cells of these mineralizing zones of endochondral ossification.Matrical reactions, with the exception of arylsulfatase and aminopeptidase, were essentially negative. The positive reactions for the latter enzymes might be an indication of their involvement in the process of extracellular mineralization.