bluuebunny/crossref_metadata_2025_split huggingface dataset:
The normal development of the blood‐testis barrier and the effects of clomiphene and estrogen treatment
Authors: Vitale Roberto , Fawcett Don W. , Dym Martin 
Published: February 2005

AbstractPrevious work with electron opaque intercellular markers has indicated that in adults occluding junctions between adjacent Sertoli cells are the principal morphological basis of the blood‐testis barrier (Dym and Fawcett, '70). Since the barrier of not present at birth this study was undertaken to determine when it is established during postnatal development of the rat and to correlate its appearance with other developmental events in the seminiferous epithelium. From birth to 16 days of age interstitially injected tracers, such as horseradish peroxidase, freely entered the seminiferous epithelium and permeated the 200 Å intercellular clefts between presumptive Sertoli cells and germ cells, reaching the center of the seminiferous cords and site of the future tubule lumen. Between day 16 and 19 occluding junctions between Sertoli cells appear and thenceforth interstitially injected electron opaque tracers were effectively prevented from reaching the tubule lumen. Therefore, in rats, the blood‐testis barrier is established between 16 and 19 days of age.In an attempt to determine whether the development of the Sertoli cell junctions and the blood‐testis barrier is under hormonal control circulating gonadotropins were suppressed using daily injections of clomiphene or estrogens from birth. The appearance of blood‐testis barrier was delayed approximately seven days in the absence of gonadotropins. However, by day 26 the Sertoli cell junctions did appear and interstitially injected tracers were prevented from reaching the tubule lumen. Thus the development of the occluding junctions between Sertoli cells that constitute the permeability barrier does not appear to be directly dependent upon gonadotropins.
Melanocyte activity in the epidermis of the Boa constrictor (Constrictor constrictor) during the sloughing cycle
Authors: Szabo George , Maderson Paul F. A. , Roth Sanford I. , Kostick Ruth M. 
Published: February 2005

AbstractEpidermal melanocytes are easily identifiable in the skin of the Boa Constrictor throughout the whole skin cycle. Intensity of the dopa reaction, however, varies. It is at its peak just before the skin enters its resting phase when the melanization of the beta layer of the epidermis is complete. There is no pigment transfer when those layers of the epidermis are formed which contain alpha keratin. The melanocytes accumulate melanosomes, retain them throughout the resting phase of the epidermis, and donate them again during the subsequent growing period of the epidermal keratinizing system when beta keratin is again formed. Thus, when a new beta layer is formed, most of the melanosomes which are donated to this layer have been formed during a previous cycle. The dermal melanophores do not show morphological or histochemical changes during the shedding cycle of the epidermis.
Morphogenetic and proliferative changes in the regenerating lung of the rat
Authors: Fisher Jean M. , Simnett John D. 
Published: February 2005

AbstractUnilateral extirpation of the lung in rats is followed by increased mitotic activity in alveolar cells of the contralateral lung, reaching a maximum six to seven days after operation. The response is delayed if the cavity created by the operation is packed with plastic sponge. Unilateral collapse of the lung without removal of tissue also leads to a contralateral mitotic response. Changes in the rate of cell proliferation evidently are not directly dependent on changes in tissue mass and it is suggested that compensatory growth in the lung may be controlled by chemical factors whose local concentration depends on variations in the rate of blood flow.Other changes which follow partial extirpation, observed particularly in the residual tissue of resected lungs, include high rates of proliferation in pleural cells, sub‐pleural tissue and bronchial epithelium. It appears that in the regenerating lung new tissue may be formed partly by the proliferation of cells in the main mass of residual tissue and partly by more localized changes in specific tissues.
The degeneration and disappearance of the centrioles during the development of the rat spermatozoon
Authors: Woolley David M. , Fawcett Don W. 
Published: February 2005

AbstractAn intensive search has failed to locate a proximal centriole in the neck of the rat spermatozoon. This centriole is present in late spermatids but disappears before spermiation. The distal centriole also degenerates during spermiogenesis, though more gradually; it is no longer demonstrable by the time the spermatozoa reach the cauda epididymidis (except as a few remnants in a small minority of the cells). The rat spermatozoon is thus exceptional among mammals in being effectively acentriolate. The implications of this are discussed. Since there are no centrioles, the activity and control of the flagellum cannot depend on a centriole as a kinetic center. Furthermore, since no centrioles are introduced by the rat spermatozoon at fertilization, there can be no paternal inheritance of a formed centriole through the cytoplasm. And, in this species at least, paternal centrioles have no role in the first cleavage of the fertilized egg.
The ultrastructural morphology and possible functional significance of mesothelial microvilli
Authors: Andrews Peter M. , Porter Keith R. 
Published: February 2005

AbstractThe serosal surfaces of major organs and tissues of the body cavities have been examined by scanning electron microscopy following fixation and critical point drying. The micrographs show that these surfaces are covered with microvilli and that the population is most dense on tissues that move about most actively in the body cavities. Radiating from the sides of the microvilli are many fine strands (150 Å, average diameter) which interconnect with each other and adjacent microvilli. Transmission electron microscopic studies of material treated with thorium dioxide at low pH or stained with ruthenium red, reveal these strands to be (1) polyanionic in nature and (2) to arise from a surface glycocalyx which coats the microvilli and intervillar surfaces. It is proposed that the serosal microvilli, together with their glycocalyx, harbor a layer of serious exudate and thereby create a slippery cushion designed to protect the thin mesothelium from frictional damage.
Myoid cells in the capsule of the adrenal gland and in monolayers derived from cultured adrenal capsules
Authors: Bressler Robert S. 
Published: February 2005

AbstractPrevious studies have demonstrated the presence of myoid cells in monolayers derived from cultured testicular fragments. In order to determine if monolayers of myoid cells can also be produced by other types of tissue cultures, monolayers derived from fragments of mouse adrenal capsules, cultured in McCoys modified 5A medium, were examined for the presence of myoid cells. The cells of the resultant monolayers contained numerous free ribosomes and abundant profiles of granular endoplasmic reticulum, as well as 40–60 Å thick filaments and associated dense bodies. In these respects they are identical to myoid cells found in monolayers in testis cultures. Contrary to earlier reports indicating that the adrenal capsule is composed of fibroblasts, this study demonstrates that myoid cells are a major component of the capsule of the rat and mouse adrenal gland.
Histochemistry of granular (poison) secretion in the skin of the frog, Rana pipiens
Authors: Dapson Richard W. , Feldman Ada T. , Wright Oscar L. 
Published: February 2005

AbstractThere are two types of granular glands in the skin of leopard frogs (Rana pipiens). Cellular glands produce fine intracellular granules rich in carbohydrate, carboxylic acids, tyrosine and sulfur‐containing amino acids. Luminal glands consist of peripherally located nuclei with scant cytoplasm. Fine granular material in these glands resembles cellular gland secretion, except that the carbohydrate is less susceptible to periodate oxidation and that a diphenol (DOPA?) is present instead of tyrosine. The prominent lumen contains large granules composed of phospholipoprotein, and are also rich in primary catecholamine and a sulfur‐containing amino acid. There was no evidence of 5‐hydroxy‐tryptamine or steroids.
I segment lengths and thin filament periods in skeletal muscle fibers of the rhesus monkey and the human
Authors: Walker Sheppard M. , Schrodt G. Randolph 
Published: February 2005

AbstractThe I segment length has been measured and the number of thin filament periods per I segment has been counted in electron micrographs of Rhesus monkey and human leg muscle fibers. The number of I segment periods in the monkey fiber (60) and in the human fiber (66) multiplied by axial periodicity (385 Å) in thin filaments of living fibers (Huxley and BROWN, '67) plus 1,000 Å allowed for Z line width in living fibers, provided a formula for calculation of I segment lengths in living fibers. The calculated I segment lengths are 2.41 μ for the monkey and 2.64 μ for the human fiber. The ratio of calculated I segment length over an assumed constant thick filament length (1.6 μ) among vertebrates is in close agreement with the ratio of measured I segment length over measured thick filament length in micrographs of frog, rat, monkey and human leg muscle fibers. The calculated I segment length in the frog (1.95 μ) is compared with that of the human (2.64 μ) to show the relation of I segment length to the length‐developed tension diagram and to the series elastic components of the skeletal muscle fiber.
Scanning electron microscopy of the fimbriae and ampullae of rabbit oviducts
Authors: Rumery Ruth E. , Eddy Edward M. 
Published: February 2005

AbstractAn initial study of the effects of long‐term ovariectomy on fimbrial and ampullar epithelia from rabbit oviducts has been made with the scanning electron microscope. Several of the rabbits were given estradiol benzoate before they were killed. These observations were compared with those of epithelial cells from similar oviductal segments from post‐ovulatory rabbits that served as controls.Fimbriae from oviducts of control animals were densely ciliated, partially concealing the bulbous processes of the secretory cells. In the ampullae the processes of the secretory cells were the predominant structure, their bulbous apices rising frequently above the tips of the cilia.When rabbits had been spayed for 16–18 months, the epithelial cells of both fimbriae and ampullae showed a remarkable change. A few cilia in small clumps were scattered among the secretory cells. The free surface of the secretory cells had become flattened and hexagonal in shape. Their microvilli were short, and from the center of each cell a thick, stubby central cilium protruded.Estrogen given the long‐term spayed rabbits caused almost complete reciliation as well as restoration of the bulbous processes of the secretory cells.
Revision of the incidence of congenital absence of dorsalis pedis artery by an ultrasonic technique
Authors: Chavatzas Demetrios 
Published: February 2005

AbstractUltrasound studies of dorsalis pedis artery in 400 feet showed the artery to be absent in 2.25%, i.e., much less frequently than it was commonly claimed. Clearer understanding of this variation and its frequency may facilitate the diagnosis of peripheral circulatory disease.
A cephalometric investigation of the sagittal growth of the second‐trimester fetal face
Authors: Johnston Lysle E. 
Published: February 2005

AbstractIt has often been reported that facial proportions remain constant throughout the fetal period. Such conclusions, however, have been based largely on the erroneous assumption that two dimensions are growing isometrically if one bears a statistically significant linear relation to the the other. In order to test the hypothesis that proportion is independent of time, sagittal histologic sections from 32 human fetuses (12–25 weeks) were analyzed cephalometrically. The linear regression on head length (HL) and the associated coefficient of correlation were calculated for each of a variety of craniofacial measures. In addition, all linear dimensions were transformed so that the size of the anterior cranial base was held constant throughout the series. It was assumed that if shape be constant, all Y‐intercepts should be zero, and angular and transformed linear dimensions should show no statistically significant linear correlation with HL. These three criteria were met uniformly by facial and anterior cranial base dimensions, but not by measurements which involved the posterior cranial base. It is concluded, therefore, that in the sagittal plane the second trimester mandible, midface, and anterior cranial base grow isometrically, while the posterior cranial base becomes relatively smaller.
Fine structural observations on the form and distribution of nuage in germ cells of the rat
Authors: Eddy E. M. 
Published: February 2005

AbstractGerm cells of the rat have been studied at the fine structural level from the time they are present in the epithelium of the embryonic gut until near the time of production of mature gametes in the adult. Particular attention has been paid to the form and location of dense, fibrous material (nuage) in the germ cells during that period of the life cycle. The nuage either exists as small discrete bodies in the cytoplasm or as “cementing material” situated in the interstices of mitochondrial clusters. It is present in primordial germ cells in the gut epithelium, in germ cells in indifferent gonads and in germ cells in sexually differentiated fetal, neonatal and adult rat gonads. It is sometimes associated with nuclear pores. Because it is present throughout much of the life cycle of the germ cells of male and female rats and it has been observed in various other mammals by previous workers, it is suggested here that it is a characteristic morphological feature of mammalian germ cells. In addition, there is considerable similarity in form and distribution of the nuage to the “polar granules” in insects and the “germinal plasm” in amphibians which are suggested to play a role in the determination of germ cells in these animals. The possibility that nuage may play a comparable role in mammals is considered.
Collagen and dermal patterns in the hypertrophic scar
Authors: Kischer C. Ward 
Published: February 2005

AbstractHypertrophic scar, mature scar, normal skin and granulation tissue were studied by transmission (TEM) and scanning (SEM) electron microscopy for characteristics and differences in fine structure, especially the collagen filaments and their physical association with each other and with interstitial components of the ground matrix.The shape of the collagen filaments is irregular and angular in granulation tissue, irregular to ovoid in hypertrophic scar, ovoid to round in mature scar, and round in normal skin. The mean diameter of the collagen filaments measures approximately 440 Å in granulation tissue, 600 Å in hypertrophic scar, 1000 Å in mature scar, and 1050 Å in normal skin.Interstitial filaments are prominent in hypertrophic scar by TEM. In nodular areas where collagen is examined in cross section the interstitial filaments often appear to interconnect long chains of collagen filaments. The interstitial filaments are not observed by SEM. Rather, by this method of observation, the demis of hypertrophic scar is seen as a homogeneous matrix, and individual collagen filaments are not observed.It is suggested that the hypertrophic scar is characterized by an unusually firm intercollagen binding by interstitial filaments, which are probably protein‐polysaccharides of the ground matrix. This relationship could account for the clinical quality of extreme hardness of the scar, and might also suggest an aberration important in the etiology of the scar.
The sheep heart: Coronary and conduction system anatomy with special reference to the presence of an os cordis
Authors: Frink R. J. , Merrick Bruce 
Published: February 2005

AbstractEach of the major coronary arteries of 25 fresh sheep hearts was injected with a different colored barium gelatin mass. Histologic sections were made of the AV node and His bundle in nine hearts. The blood supply to this region was traced radiographically, photographically and histologically. X‐rays of the upper ventricular septum were taken before and after coronary injection to demonstrate an os cordis.The sinus node is always supplied by a branch of the right coronary artery. The crux of the heart, and subsequently the AV node, is always supplied by the circumflex artery. The unbranched His bundle, unusually long in sheep, receives a dual blood supply from both the anterior septal branches and the AV node artery. The proximal part of the left and right bundle branches is supplied by the anterior septal branches in the majority of hearts. Intercoronary anastomoses are present in the majority of hearts, particularly in the upper ventricular septum.An os cordis, deep in the atrial septum and directly adjacent to the AV node, was found in all 25 hearts. Occasionally, a second bone was found in the anterior part of the left atrioventricular ring.
Myoneural junctions in the extraocular muscles of the mouse
Authors: Salpeter Miriam M. , McHenry Frances A. , Feng Hsuan‐Hua 
Published: February 2005

AbstractThe very fast extraocular muscles have both singly and multiply innervated fibers. The former are among the fastest vertebrate muscle fibers on record, whereas the latter are very slow. In this study single and multiple myoneural junctions were first identified in whole eye muscles of the mouse after staining for cholinesterase. Each group was then embedded separately for electron microscopy. Approximately 10% of the fibers were found to be multiply innervated. The multiple endings and the fibers they innervate resemble those of the tonic bundles of the frog. The majority single endplate is very large in surface view, has sparse junctional folds, and innervates a fiber very rich in mitochondria. These observations were contrary to some frequently held views regarding neuromuscular junctions of very fast fibers. A minority single endplate is smaller, has more junctional folds and innervates a large fiber with fewer and smaller mitochondria.
On the synaptogenic sequence in the chick retina
Authors: Hughes W. Frank , LaVelle Arthur 
Published: February 2005

AbstractStudy of the developing chick retina with the electron microscope revealed that dyad ribbon synapses begin to form in the inner plexiform layer before synaptic ribbons begin to appear in photoreceptor terminals of the outer plexiform layer. This centrifugal (inner to outer) sequence of synaptogenesis in the predominantly cone retina of the chick differs from the centripetal sequence that has been reported for the predominantly rod retinas of the mouse and rat. This difference does not favor the hypothesis, suggested by others, that the photo‐receptor may influence the maturation of inner retinal elements. The different patterns of synaptogenesis are discussed briefly with reference to anatomical differences between the retinas of different species.
Anatomy of the ferret heart: An animal model for cardiac research
Authors: Truex Raymond C. , Belej Rhoda , Ginsberg Linda M. , Hartman Rickey L. 
Published: February 2005

AbstractThe hearts of 38 black‐footed ferrets (Mustela nigripes) were studied with the use of physiologic, microdissection, vascular injection and histologic methods. These animals had a mean heart rate of 265 per minute, a heart weight of 3.7–5.2 gm, and a mean aortic pressure of 139.5 mm Hg. The predominant left coronary artery supplied usually both the SA and AV nodes, as well as the AV bundle, bundle branches and most of the ventricular myocardium. The cells of a well differentiated cardiac conduction system increase in cytoplasmic diameter from the SA node to the distal bundle branches. A cartilaginous right fibrous trigone and thick anulus fibrosus form useful landmarks for delineating AV node and AV bundle relationships. Small size, discrete nodal masses and a unique coronary arterial pattern make this heart an ideal model for histochemical, ultrastructural, electrophysiologic and pathologic circulation research.
The functions of semispinalis capitis and splenius capitis muscles: An electromyographic study
Authors: Takebe Kyoichi , Vitti Mathias , Basmajian John V. 
Published: February 2005

AbstractThe functions of the normal semispinalis capitis and splenius capitis muscles of fifteen subjects were evaluated electromyographically with bipolar fine‐wire electrodes. The voltage‐output data were integrated and analyzed by computer and showed that the main function of semispinalis capitis is limited to extension of the head. However, splenius capitis both extends the head and rotates it to its own side.
Perineal musculature in the cat
Authors: Martin William D. , Fletcher Thomas F. , Bradley William E. 
Published: February 2005

AbstractMuscles of the perineal region were dissected in 20 cats. Levator ani muscle was composed of two parts: iliocaudalis and puboischiocaudalis; both parts inserted entirely on caudal vertebrae, as did the coccygeus muscle. A well developed band of smooth muscle, the pars analis of retractor penis (clitoridis), inserted on the anal canal to retract the anus. The external anal sphincter had pars caudalis and pars cranialis divisions, the latter covered paired anal sacs. In addition, a distinct sphincter encircled each anal sac duct. In the male, levator scroti muscle originated from external anal sphincter. There was no continuity between external anal sphincter and bulbospongiosus muscles. Cremaster muscles were absent in the cat. In the female, pars cranialis of external anal sphincter gave origin to the constrictor vestibuli muscle, and pars caudalis to constrictor vulvae muscle. Bulboglandularis muscles were present in both sexes. Urethralis, ischiourethralis, and ischiocavernosus muscles in the cat were similar to other quadripeds.
Surface coats of the mouse blastocyst and uterus during the preimplantation period
Authors: Enders Allen C. , Schlafke Sandra 
Published: February 2005

AbstractA glycoprotein coat is demonstrable on the free surface of both the blastocyst and uterine luminal epithelium of the mouse on day 4 and day 5 of normal pregnancy, and on day 7 of delayed implantation, using concanavalin A‐peroxidase and ruthenium red. The coats are apparently negatively charged, as shown by their binding with colloidal thorium dioxide. The cell coat on uterine epithelium is appreciably thicker than that on the blastocyst. The information currently available is sufficient to suggest that simplistic mechanisms such as change in charge or total thickness cannot be the sole basis of initial adhesion, but that some localized reduction of the uterine surface coat accompanies adhesion. However, considerably more information is necessary concerning the nature of the surface coats before a more comprehensive understanding of the role of adhesion in implantation can be achieved.