bluuebunny/crossref_metadata_2025 huggingface dataset:
Endosteal deposition of bone at the midshaft of the second metacarpals of adolescent females
Authors: Johnston Francis E. , Watts Elizabeth Smithgall
Published: February 2005

The endosteal and periosteal diameters of the second metacarpal were measured at the midshaft on radiographs of 62 normal girls at 11.0 ± 0.5 years (pre‐menarche) and again at 16.0 × 0.5 (post‐menarche). There was an average increase in the periosteal diameter of 10% and an average decrease in the endosteal diameter of 16%, both changes significant at p < 0.01. Individual variability was greater for the endosteal than the periosteal surface changes (p < 0.01).
Changes in the fine structure of satellite cells surrounding chromatolytic neurons
Authors: Dixon John S.
Published: February 2005

The fine structure of satellite cells surrounding neurons in the superior cervical ganglia of the rabbit is described. These observations form a basis for the interpretation of fine structural changes which occur in the satellite cells after post‐ganglionic section. Early changes consist of an increased number of micropinocytotic vesicles indicating an enhanced uptake of extracellular materials. The mitochondria increase in length and lie close to the plasma membranes, reflecting the increased energy requirement of these cells. Many develop intramitochondrial granules which may be concerned with the transport of water or ions. Later, at the height of chromatolysis, the satellite cells increase their quantity of granular reticulum and many possess agranular sub‐surface cisternae whose function may be to direct material synthesised in the satellite cells to the nerve cell surface. Individual layers of satellite cell cytoplasm may slide over one another to accommodate the increased size of the neurons during chromatolysis. The satellite cell processes appear thickened and contain large numbers of fine filaments which may be formed by the breakdown of microtubules.
Ovarian activity in the intact or hypophysectomized pregnant mouse
Authors: Choudary Jasti B. , Greenwald Gilbert S.
Published: February 2005

Various parameters of ovarian activity were determined for the intact or hypophysectomized pregnant mouse, as a baseline to establish the nature of luteotropic hormones in this species.

Seventeen per cent of White Swiss mice with a vaginal plug were not pregnant at subsequent stages of gestation. The greatest number of failures occurred between days 12 and 15 of pregnancy, coinciding with the temporary absence of antral follicles and regressive changes in the vaginal epithelium. This suggests that there is a period of transient hormonal imbalance before full placental function is established, which is responsible at this time for the peak in embryonic mortality.

Two periods of luteal growth were apparent between days 1 and 4 and 10 to 14 of pregnancy. The first histologic evidence of luteal regression occurred at day 16, correlating with renewed squamous cell proliferation of the vaginal mucosa.

There were no significant differences in the number of ova shed on day 1 of pregnancy (11.0 ∓ 0.5 ova) and the subsequent number of embryonic swellings at any stage. Gestation in intact pregnant mice lasted 18 days (n = 2) or 19 days (n = 36). The number of young counted late on day 1 post partum (9.1 ± 0.5) was significantly less than the number of embryonic swellings as a result of maternal cannibalism.

Hypophysectomy on day 1 of pregnancy led to rapid histologic degeneration of the corpus luteum. In this feature, the mouse resembled the hamster rather than the rat. Day 10 of pregnancy represented the earliest time at which, at least in some animals the pituitary could be removed and pregnancy continue. Following hypophysectomy from day 11 on, luteal activity, continuation of pregnancy, fetal and placental weight and vaginal histology were comparable to intact, pregnant mice. This is similar to the hypophysectomized rat in the latter half of pregnancy but differs from the situation in the hamster.

On the basis of the present findings and results in the following paper, it appears likely that the mouse placenta, in addition to secreting a prolactin‐like hormone, also produces other gonadotropins.
Fine structure of canine Kupffer cells and their microtubule‐containing cytosomes
Authors: Boler R. Keith
Published: February 2005

The ultrastructure of Kupffer cells of canine liver has been studied and described. Kupffer cell nuclei were elongated and irregular in shape having a prominent double nuclear envelope containing scattered ribosomes on the outer membrane. Mitochondria were small, relatively scarce, and contained few mitochondrial granules. Elements of endoplasmic reticulum were scarce and highly irregular in form. In general, the cytoplasm was less dense than hepatocytes and contained fewer organelles which were less compactly arranged than in hepatocytes. Microbodies were not observed in any of the Kupffer cells studied. The cytoplasm contained various numbers of large phagosomes but consistently contained numerous dense cytosomes of various sizes. The most striking finding was that many cytosomes and phagosomes contained large numbers of short microtubules approximately 350 Å in diameter which were arranged in clusters and were associated with membanes.
The fine structure of rabbit platelets fixed in acetaldehyde
Authors: Gardner H. Allen , Simon Gérard , Silver Malcolm D.
Published: February 2005

The morphology of platelets fixed in acetaldehyde and postfixed in osmium tetroxide was compared with that of platelets fixed in glutaraldehyde followed by osmium tetroxide. Many platelets became rounded after acetaldhyde fixation. Membranes, granules and mitochondria were well preserved and cytoplasmic microfilaments became apparent. Very dense granules were obvious after acetaldehyde fixation alone and after acetaldehyde/glutaraldehyde/osmium tetroxide triple fixation, but not after acetaldehyde/osmium tetroxide double fixation. Microtubules were never seen. Intracytoplasmic vacuoles assumed exaggerated prominence. The authors relate the alterations in the vacuolar system and changes in platelet shape to a loss of cytoplasmic microtubules. They suggest that the changes are induced, in part by the low temperature of fixation, and in part by the weak fixative action of the aldehyde.
The globule leucocyte in the intestinal mucosa of the cat: A histochemical, light and electron microscopic study
Authors: Takeuchi Akio , Jervis Helen Roland , Sprinz Helmuth
Published: February 2005

Globule leucocytes (GL) first noted by Weill ('19) in the intestinal tract of certain mammals, have been described, since, in many species. The classification and function of these cells, however, is still under discussion. We have studied GL in the cat using histochemistry at light and electron microscopic levels. In this species, GL are concentrated in the intestinal mucosa; they are found less frequently in the gallbladder and only rarely in other organs. GL are usually located between the epithelial cells of the gut, seldom in the underlying lamina propria. They appear to be migratory cells of mesenchymal origin, representing an independent cell population. GL are characterized by large eosinophilic globules in their cytoplasm. The globules contain strongly basic proteins associated with phospholipids and neutral mucosubstances which, in the colon, are encased in a capsule of sulfated mucosubstances. At the ultrastructural level the typical globules consist of a dense, homogeneous matrix enclosed by a single membrane; they show, however, great variation in their morphologic appearance, reflecting, possibly, different stages in the process of accretion and utilization of their content.
Electron microscope observations on the shell gland mucosa of calcium‐deficient hens (Gallus domesticus)
Authors: Nevalainen Timo J.
Published: February 2005

Calcium‐deprivation of three weeks duration causes marked degenerative changes in the shell gland mucosa of the laying hen. The height of the columnar epithelium decreases, but the secretory granules in the columnar epithelial cells and the cilia on the apical cells of the columnar epithelium are preserved. The tubular glands decrease in size and number. The microvilli surrounding the tubular gland lumen disappear. The cytoplasm of the tubular gland cell contains autophagic vacuoles (cytolysomes) and large pigment accumulations, presumably lipofuscin. The changes are due to dietary calcium deficiency, apparently mediated by decreased sex steroid secretion and decreased stimulation of the oviduct. These changes are totally reversible, since the fine structure of the shell gland mucosa of calcium‐deprived hens returned to a normal laying diet does not show any signs of degeneration and is identical with the fine structure of the shell gland mucosa of the laying control birds.
The ultrastructure of sympathetic ganglia of the lizard Cnemidophorus neomexicanus
Authors: Colborn Gene L. , Adamo Norma Jean
Published: February 2005

Sympathetic ganglia of six Cnemidophorus neomexicanus lizards were fixed by immersion with glutaraldehyde or a combination of glutaraldehyde and paraformaldehyde. All ganglia were post‐fixed in 1% osmium tetroxide and embedded in Epon.

Neuronal somata and processes of stellate ganglia were ensheathed typically by capsular cell cytoplasm and membranes; however, parts of some processes were invested only by basement membrane. Axo‐somatic, axo‐dendritic and axo‐axonal synapses were observed. Pre‐ and post‐synaptic processes contained 200 Å neurotubules, 100 Å neurofilaments, 225–500 Å presumptive glycogen granules and occasional multivesicular bodies. Presynaptic endings contained 500–700 Å “clear” vesicles and a few dense‐cored vesicles of 600–1100 Å.

Aggregates composed of 225–500 Å granules, presumably glycogen, were frequently found in peripheral perikaryal positions in intimate association with lipid droplets. Clusters of particles within somata were also found which resembled ribosomes but were not associated with endoplasmic reticulum or vesicular membranous elements. These clusters, perhaps “areticular Nissl substance,” were associated in some instances with fibrillar material or lattice‐like granular structures. Abundant and frequently large lipid droplets were observed in proximity to the ribosomal‐like particulate material.
The cilium on mammalian vestibular hair cells
Authors: Hamilton David W.
Published: February 2005

The mammalian vestibular cilium is described. It is shown to be comprised of nine dense outer fibers and an intermittent central density; this stands in contradistinction to vestibular cilia of non‐mammalian species that have been shown to be comprised of nine outer doublet tubules surrounding two central tubules. The possible functional meaning of these observations is discussed.
Maintenance of gestation in hypophysectomized rats with highly purified pituitary hormones
Authors: Ahmad N. , Lyons W. R. , Papkoff H.
Published: February 2005

Pregnancy was maintained in Long‐Evans rats hypophysectomized on day 1 and injected with ovine pituitary gonadotrophins from day 1 through day 11; and also in rats hypophysectomized on day 6 and injected from day 6 through day 11. For successful maintenance until term, no further injections were necessary after day 11. The combination of hormones considered close to optimal was; mammotrophin 2.5 mg; follicle‐stimulating hormone 25 μg; and interstitial cell‐stimulating hormone 5 μg injected daily, subcutaneously. Histological examination of ovaries after this regimen (on day 12) revealed interstitial and luteal tissue that was considered normal for this stage; and follicles that were in some cases larger than expected and occasionally with theca luteinization. The ovaries of the rats allowed to go to term and untreated after day 11 showed follicular and interstitial tissue that had regressed and well‐stimulated corpora lutea. These findings showed no evidence of placental FSH or ICSH‐like hormones; but confirmed earlier reports of a rat placental luteotrophic hormone.
The occurrence of tubular intramitochondrial inclusions in the post‐mortem zona fasciculata of the rat adrenal
Authors: Dietert Scott E.
Published: February 2005

Adult male albino rats are decapitated and the mitochondria in one adrenal gland are examined at increasing post‐mortem time intervals in the electron microscope. The contralateral adrenal gland is excised rapidly, immersed in aldehyde fixative, diced, and used as the control. As early as 15 minutes postmortem, tightly packed sheaves of tubules (each tubule measuring 140 AR in outside diameter) appear as inclusions in the matrix of mitochondria within the zona fasciculata. These inclusions occur in increasing numbers of mitochondria during the first hour postmortem, until 10‐25% of the mitochondria examined contain at least one sheaf of tubules. Observations at two and three hours post‐mortem reveal no significant increase in inclusion‐containing mitochondria. At these late time intervals additional post‐mortem alterations are evident: (1) a decrease in mitochondrial matrix density; (2) swelling of mitochondrial cristae; and (3) vesiculation of the smooth reticulum. Kjaerheim ('67), Wheatley ('68), and Magalhaes and Magalhaes ('68) have described tubular inclusions in the matrix of “normal” rat adrenal mitochondria which are identical to the post‐mortem inclusions described in this study. The presence of such inclusions in control mitochondria has been observed by the author on one occasion: within a degenerate mitochondrion enclosed inside a cytoplasmic membrane‐limited vacuole. The possible significance of this post‐mortem mitochondrial alteration in the rat adrenal cortex is discussed.
The fine structure of endothelial cells of toad arteries
Authors: Piezzi Ramón S. , Santolaya Ricardo C. , Bertini Francisco
Published: February 2005

The vascular endothelia of the aortic, iliac and kidney arteries of the toad Bufo arenarumH. and the frog Leptodactylus chaquensis were studied with the electron microscope. The shape and size of the endothelial cells appear to depend upon whether the internal elastic membrane is stretched or contracted. These cells present the following characteristics: (1) an elongated and folded nucleus, (2) large bundles of oriented filaments, (3) acid phosphatase‐positive micropinocytotic vesicles, (4) small, dense, spherical granules surrounded by a single membrane. These cytoplasmic granules, also studied by histochemical techniques, are of unknown nature and function.
Changes in coronary arteries of mice fed a high‐fat, low‐protein diet followed by a normal diet
Authors: Ashburn Allen D. , Smith‐Vaniz George T. , Wilson Jack L. , Lane Williams W.
Published: February 2005

Female mice of a Swiss albino stock were fed a high‐fat, low‐protein, hypolipotropic diet which produces rapid cardiovascular lesions in this stock of mice. Half of the animals were killed after 45 days and the others were placed back on a diet of normal laboratory chow and killed after one, two and three weeks of refeeding.

In animals killed after receiving the experimental diet for 45 days small, focal deposits of hyalin in media of large coronary arteries of the right ventricle was the major change.

During the first week of recovery (fed a normal diet) the incidence and severity of arterial lesions increased and within individual hearts arteries of all sizes and in both atria and both ventricles were involved. Following hyalinization an acute arteritis developed that involved all layers of the arterial wall and extended into the perivascular space.

After two and three weeks recovery the coronary arteries were characterized by a periarterial fibrosis and by a decrease or absence of the leucocytic reaction. A subendothelial hyperplasia of smooth muscle, arranged longitudinally, was accompanied by an increase in reticular and collagenous fibers. Circular smooth muscle in the media was also hyperplastic.
Morphological studies of the embryonic rabbit thymus: The in situ epithelial versus the extrathymic derivation of the initial population of lymphocytes in the embryonic thymus
Authors: Ackerman G. Adolph , Hostetler Jeptha R.
Published: February 2005

The present morphological investigation of the developing thymus of the rabbit during early embryogenesis differs with our previous studies concerning thymus lymphopoiesis in the chick and hamster which suggested that embryologically the first lymphocytes appearing in the thymus arise in situ by the direct transformation of undifferentiated epithelial cells comprising the organ parenchyma. Significantly, in the rabbit and in contrast with the chick and hamster, a few cells morphologically resembling but not completely identical to medium‐size and large lymphocytes were evident in the mesenchyme near the thymus at a time just prior to the appearance of lymphocytes or lymphocytic precursors within the thymus parenchyma (twelve and one‐half days of gestation). Within a few hours after the appearance of these extrathymic lymphocytic cells both medium‐size and large lymphocytic cells were observed both in the thymus parenchyma and in the mesenchyme (thirteen and one‐half days of gestation); these cells remain more numerous in the mesenchyme than in the thymus during the next several days. In some instances, only a thin basement membrane separated the lymphocytic cells within the thymus from the surrounding mesenchyme. In contrast with our earlier studies, several examples have been encountered between the fifteenth and seventeenth days of gestation of lymphocytic cells extending through the basement membrane seperating the thymus parenchyma from the surrounding capsular connective tissue. Morphologically cellular modulations between thymus undifferentiated epithelial cells and lymphocytic precursors have not been as convincing in the developing rabbit thymus as in the chick and hamster. In contrast with thymus development in the chick few mature or developing granulocytes are found near the embryonic rabbit thymus indicating that the primitive extrathymic lymphocytic cells are not myeloblasts.

The morphological evidence of this investigation is consistent with the thesis that the first lymphocytes present in the embryonic thymus probably are derived from the invasion of extrathymic lymphocytic cells into the organ parenchyma rather than forming in situ from modulating undifferentiated epithelial cells. The presence of rare lymphocytic cells observed in the small vascular channels near the time of appearance of the lymphocytic cell population in the mesenchyme and within the thymus primordium would be consistent with the view that these primitive lymphocytic cells immigrate to the region of the thymus via the blood vascular system.
Specialized intercellular junctions in tumor cells—An electron microscope study of mouse sarcoma cells
Authors: Clarke Michael A.
Published: February 2005

Specialized intercellular junctions have been observed in 3‐methylcholanthrene‐induced mouse sarcomas. These junctions are of two morphologic types and appear to be focal in nature. The first type consists of an approximation of the plasma membranes of adjacent cells to within 200 Å of one another. In the junctional region the intercellular space and the adjacent cytoplasm are of increased density. The second type of junction is more complex, the intercellular space being of greater width and containing a dense central plaque. The intercellular space and the adjacent cytoplasm are of increased density. Such junctions may serve a role in structural support of the tumor mass.
The histology and rate of tooth eruption with and without temporary impaction in the dog
Authors: Cahill Donald R.
Published: February 2005

Eruption was studied by experimentally impacting and releasing permanent premolars in puppies. Eruption rates of both normal and experimentally delayed teeth were calculated from weekly radiographs. The rate of normal eruption is triphasic and similar to a normal growth curve. It has an initial slow exponential rate which changes to a more rapid exponential rate followed in turn by a terminal plateau. All of the teeth released from impaction erupted and their rates exceeded or equaled the normal rate.

The morphology of the bony trabeculae beneath the erupting teeth and the relative amount of soft tissue between the bone and teeth are expressions of the eruptive rate. The trabeculae around rapidly erupting teeth are thinner, more delicate and more widely separated from one another than those of slowly erupting teeth. Trabecular orientation aligns with the direction of eruption, showing not only its vertical component, but also whether the tooth moved mesially or distally during eruption.
Fenestrated venules of the large salivary glands
Authors: Takada Mitsuya
Published: February 2005

Endothelial fenestrations have been observed in the venules of the large salivary glands of mice. The structure of the fenestrations is similar to those of capillaries. The fenestrations are frequently demonstrated in the endothelium of the transitional portions from a capillary to a venule. They are also seen in overlapping thin cytoplasm located on either the blood or tissue front of the endothelial cells of the venules at cell junctions.
Ultrastructural study of rat mammary gland during pregnancy
Authors: Murad Tariq M.
Published: February 2005

Virgin female Sprague‐Dawley rats were mated, and after the appearance of vaginal plugs were placed in individual cages. The animals were sacrificed at different intervals from the second day of gestation until delivery. Breast tissue was studied with the light and electron microscope.

The study suggests that breast tissue undergoes changes as early as four days after fertilization and continues throughout pregnancy. The changes start with accumulation of many ribosomes and polysomes within the epithelial cell cytoplasm. Lipid droplets appear early and increase in number as pregnancy advances. Two types of proteinaceous particles appear within the cytoplasm on the seventh day of gestation, and are totally secreted into the lumina before parturition. The particles are believed to play a role in colustrum composition. The Golgi apparatus plays no role in the formation of the proteinaceous particles. The particles are formed in relation to rough surfaced endoplasmic reticulum.

The changes seen are limited to the ductular epithelium and are not seen in the large ducts. In animals treated with colchicine, mitoses are seen in the ductular epithelium very early in pregnancy and continue throughout the gestation period.
Volumetric composition of the rabbit skeleton
Authors: Gong J. K. , Ries W.
Published: February 2005

Four rabbit skeletons were completely analyzed for marrow contents by means of a volumetric technique developed previously in a study of the dog skeleton (Gong and Arnold, 1965). The distribution of the marrow in various skeletal areas as well as the relative contents of the three marrow components (water, fat and non‐fatty organic fraction) were determined.

It was found that more than two‐thirds of the rabbit marrow was located in the various flat bones and one‐third in the long bones. In spite of this, almost half of the skeletal marrow fat was located in the long bones. The nonfatty organic fraction of the marrow in the long bones, on the other hand, constituted only one‐sixth of that found in the whole animal skeletal marrow. In terms of total marrow, about 51% of the rabbit skeletal volume was marrow. Based on the concept that fat‐free marrow is a more adequate index of active marrow than the red marrow (Gong and Arnold, 1965), the distribution of the various centers of marrow activity was described and discussed.
The vascular stiffening mechanism in the tongue of the echidna (Tachyglossus aculeatus)
Authors: Doran G. A. , Baggett H.
Published: February 2005

An extensive vascular arrangement resembling erectile tissue is described in the tongue of an anteating Monotreme, the Echidna. Its possible function as a stiffening mechanism is discussed in relation to observations on living animals.
Electron microscopy of chromosomal changes in ambystomal somatic cells during the mitotic cycle
Authors: Bloom William
Published: February 2005

This sequence of electron micrographs shows the progressive changes undergone by the dispersed chromosomal fibrils of the interphase nucleus as they begin to condense, in early prophase, into clumps centered on three types of small nuclear structures. These bodies do not seem to have been described previously in detail in connection with mitosis, although they were mentioned as a group in a preliminary note by Bloom (1963). In the present report they are divided into three groups indicated as F1, F2 and F3 and are labelled 1, 2 or 3 in the accompanying electron micrographs.

The clumps enlarge by continued accretion of more and more fibrils concentrated about these three types of bodies until the chromosomes of metaphase are formed. The inference that the bodies depicted here form focal points for the condensation of dispersed chromosomal filaments rests solely on the repeated finding of the progressive aggregation of the fibrils about them. Further studies are in progress on factors mediating these changes and on the nature of the F bodies.
Fine structure of the alveolar macrophage of the cat and modifications of its cytoplasmic components during phagocytosis
Authors: Collet A. J.
Published: February 2005

The alveolar macrophage of the cat shares some features with the alveolar macrophages of ordinary laboratory mammals and man, mainly a voluminous Golgi zone exhibiting evidence of secretory activity. The very numerous typical lysosomes appear to be a secretory end product. They increase in size by a fusion process. At some stage of this process dense periodic structures, crystal‐like, become visible in intermediate size lysosomes, which later form heterogeneous crystal‐like granules characteristic of the cat's alveolar macrophage.

The crystal‐like granules are bounded by a unit‐membrane pattern and contain a dense periodic parallel lamellar material (crystal‐like) mixed with fluffy amorphous substance and surrounded by a clear homogeneous material. Based on its structure as observed at a high magnification, and its behavior during phagocytosis, this crystal‐like material appears to be composed of lipid.

Intra‐pulmonary injection of red blood cells was carried out in order to observe the fate of the crystal‐like granules during phagocytosis as compared to that of typical lysosomes. Like typical lysosomes the crystal‐like granules become reduced in number and undergo incorporation to the phagocytic vacuoles, demonstrating their lysosomal nature.
On the occurrence of microtubules within mature astrocytes
Authors: Raine Cedric S. , Wiśniewski Henryk
Published: February 2005

Microtubules have been described to occur frequently within the subpial fibrous astrocytes of the adult spinal cord of three species. This finding is related directly to perfusion fixation by glutaraldehyde. Immersion fixation produced no or fewer tubules in this area. It is suggested that the presence of microtubules in these cells might reflect a specific skeletal function. Astrocytes from other locations within the central nervous system displayed fewer microtubules within their cytoplasm.
Selective effects of testosterone and isoproterenol upon regenerating submandibular gland isografts in BALB/c mice
Authors: Hoshino Kazumasa , Lin C. D.
Published: February 2005

Single submandibular glands were isografted intraperitoneally to normal BALB/c mice. From the day following transplantation, 20 mg testosterone enanthate fortnightly, or daily intraperitoneal injections of 0.25 mg per gram body weight of isoproterenol‐HCl were given. Control mice were untreated. The grafts were removed from five mice in each group 1, 2, 4, or 8 weeks after grafting. Regardless of treatments, only ductal cells were observed one week after transplantation. With testosterone treatment for longer than two weeks, their remaining ductal cells tended to accumulate secretory granules. Some appeared to be secretory tubules resembling those in the glands of normal adult male mice. When the glands were transplanted from females to male hosts, surviving grafts responded to endogenous androgen of the hosts, and some secretory tubules reappeared without testosterone treatment. Contrarily, with isoproterenol treatment for longer than two weeks, acinar cells reappeared in the grafts, but no secretory tubules were observed. The remaining ductal cells often underwent hyperplastic changes with reappearing tubules or acinar cells amongst them corresponding to post‐transplantational treatment. Mechanisms of differentiation of these three different components of submandibular glands were found to be different and each had specific affinity to testosterone or isoproterenol. Grafts were removed from hosts treated with testosterone for two months, and when 4 or 8 of these grafts were retransplanted into each new host, they demonstrated a lethal effect.
Fine structure of a third epithelial component of the thyroid gland of the rat
Authors: Calvert R. , Isler H.
Published: February 2005

Duct‐like structures made of cells different from follicular or light cells were observed with the electron microscope in the thyroid glands of 16 rats. The wall of most of the ducts was made of two types of cells: (1) the lumen‐bordering cells, mostly cuboidal or columnar, with short microvilli, and (2) the subjacent squamous cells, arranged in one or several layers of cells displaying numerous desmosomes and dense bundles of tonofilaments. Both cell types showed intricate folding of the plasma membrane at sites of cell‐to‐cell contact, an abundance of free ribosomes and nuclear indentations. In one occasion mucous‐like cells were found. The lumen contained a finely granular homogeneous material as well as cell remnants. The ducts were located among the follicles, and were ususally discrete from them; but on four occasions the epithelium of the duct was seen in direct continuity with that of a thyroid follicle. Only one case of a light cell associated with a duct was observed while many of these cells were associated with thyroid follicles.
Correlation of ovarian abnormalities in young golden hamsters with ovarian estrogens and progesterone
Authors: Kent Harry A. , Mandel Jeffrey A.
Published: February 2005

A correlation between ovarian steroids and ovarian abnormalities is demonstrated. The decrease in levels of ovarian estrogen and progesterone is correlated, one week later, with an increase in polyovular follicles and then in multinucleate ova. The time sequence of the onset of ovarian abnormalities, as correlated with levels of estrogens and progesterone are an indication of the possibility of hormonal control of the ovarian abnormalities.
Morphological‐histochemical comparison of dog and cat splenic ellipsoid sheaths
Authors: Jacobsen Glenn
Published: February 2005

Investigations were made on the morphological and histochemical nature of the ellipsoid sheaths of two different types of spleens, sinusal and non‐sinusal, as found in the dog and cat respectively.

Ellipsoid cells of dog and cat spleens respond similarly with Marshall's silver impregnation method as well as demonstrate activity for the hydrolytic enzyme, acid phosphatase. Both technics substantiate ellipsoid involvement in the reticuloendothelial system. Nonspecific esterase, another hydrolytic enzyme commonly found in phagocytic cells, was demonstrated in the cat ellipsoid cells but not in similar cells of the dog spleen indicating a basic difference in the physiological activity of the dog and cat ellipsoid cells.
Fine structure of the interstitial cells of leydig in the squirrel monkey during seasonal regression
Authors: Belt W. D. , Cavazos L. F.
Published: February 2005

The fine structure of the interstitial cells of Leydig has been examined in the squirrel monkey, Saimiri sciureus, during the non breeding portion of the year when the testes are essentially azoospermic. Interstitial cells are present in abundance as a layer, several cells thick, on the inner aspect of the tunica albuginea. Cytologically, the cells possess the characteristics usually associated with cells which synthesize and secrete steroid hormones: an abundant agranular endoplasmic reticulum in the form of anastomotic tubules; mitochon‐chondria with both lamellar and tubular cristae; only a few strands of granular endoplasmic reticulum; a Golgi apparatus and associated vesicles, some of which are of the coated variety; a varying population of lipid droplets and dense bodies. Some of the dense bodies appeared to be lipofuscin pigment. A previously undescribed inclusion was frequently encountered which consisted of arrays of a honeycomb like structure. Most frequently these structures were present near the cell periphery or in blunt protrusions of the cytoplasm.
The ultrastructure of the human adrenal medulla: With comparative studies of white rat
Authors: Brown W. Jann , Barajas Luciano , Latta Harrison
Published: February 2005

There is wide support for the concept that there are two types of secretory cells in adrenal medulla of various species. One cell is filled with electron dense bodies believed to contain norepinephrine; the other cell's lesser stained bodies contain epinephrine. This differential density may be seen by fixation in osmium tetroxide after glutaraldehyde.

The two cell types have not been clearly shown in human tissues. Such a failure may be related to fixation. In consideration of this, fresh human adrenal was fixed in cold 1% glutaraldehyde, then 1% osmium tetroxide — a procedure known to give satisfactory differentiation in other species. A parallel study with rat tissue was then done.

Electron microscopy revealed two types of cells in rats, while in man an obvious cell difference was not found. There is, however, a clear difference in human chromaffin granule density, which implies that the human cells have random numbers of both light and dark granules. The morphologic difference of the cell types in man may be less distinct than in the rat. Another possibility is that in cells with predominantly dark granules, there are co‐mingled lighter granules with the coexistence of cells of opposite dominance. Both hormones then would occur in the same cell in varying proportions according to functional demand. It seems highly unlikely that two distinct cell types would have been overlooked with wide sampling, however, in a study of three adrenal glands, one cannot rule out their existence.
Distribution of cell web‐containing epithelial reticular cells in the rat thymus
Authors: Pereira G. , Clermont Y.
Published: February 2005

In sections of thymus stained with the tannic acid‐phosphomolybdic acid‐amido black (TPA) technique, the epithelial reticular cells can readily be identified by the well‐stained tonofibrils in their cytoplasm. In the cortex, flattened epithelial reticular cells form a continuous layer on the inner surface of the capsule and along the interlobular septa. Within the cortex proper, stellate epithelial reticular cells are widely dispersed as a loose network. In the medulla, two zones, referred to as “outer” and “inner” medulla, are distinguished. The outer medulla, like the cortex, contains epithelial reticular cells, but these are more voluminous, are more richly provided with tonofibrils and form a denser network than in the cortex. In the inner medulla no epithelial reticular cells can be seen but instead connective tissue cells and fibers make up the supporting framework. A layer of flattened epithelial reticular cells demarcates the outer from the inner medulla. This layer of cells also extends along the outer surface of blood capillaries seen in the outer medulla and cortex. Around the larger blood vessels, this layer of epithelial reticular cells is separated from the vessel wall by a connective tissue perivascular space. Hence, the inner medulla is continuous with the perivascular spaces and, like them, is supported by connective tissue. Thus, the epithelial reticular cells constitute the supporting framework of the cortex and outer medulla and separate these regions from the connective tissue of the capsule, interlobular septa, blood vessels and inner medulla.
A study of some histochemical and phagocytic reactions of the reticuloendothelial system of the rabbit spleen
Authors: Snodgrass Michael J. , Snook Theodore
Published: February 2005

Questions concerning the nature of the intermediary vascular pattern make up a considerable portion of the literature concerning splenic morphology. Evidence indicates there is a special association between the reticuloendothelial system (RES) and the intermediary capillary terminations. This study was undertaken to characterize the distribution of the RES in the rabbit spleen and to correlate this with the vascular pattern described by Snook ('58). Like cells of the RES throughout the animal body, splenic RE cells can be demonstrated by several histochemical and functional methods. They are metalophilic (argyrophilic), possess several hydrolytic enzymes, and phagocytose injected particulate matter. Cells demonstrated by these methods are found in the marginal zone, and in the lumen of the red pulp sinuses but most are localized in the red pulp cords. This distribution corresponds closely to the termination of arterial capillaries in the marginal zone and pulp cords in the rabbit spleen and supports the general hypothesis that there is a unique and intimate relationship between the vascular system and the RES at these points.

The sinus lining cells react characteristically to the techniques employed. They are sporadically metalophilic, strongly positive for nonspecific esterase (endoplasmic reticulum), negative for acid phosphatase (lysosomal), and occasionally contain small particles of injected matter. They probably represent a functionally distinct cell population.
Intercellular bridges between follicle cells and oocyte in the lizard, Anolis carolinensis
Authors: Neaves William B.
Published: February 2005

Certain cells in the follicular epithelium of lizard (Anolis caro‐linensis) ovaries are connected to the oocyte by true intercellular bridges. Unlike other known intercellular bridges, these may form by secondary cell contact and membrane fusion rather than by incomplete cytokinesis. These intercellular bridges are abundant in previtellogenic tertiary follicles, and they contain glyco‐gen, ribonucleoprotein particles, and a dense, fibro‐granular material which may be exchanged between the two cells. Prior to the onset of yolk accumulation in the oocyte, the intercellular bridges and the pyriform cells from which they originated disappear from the follicular epithelium. The abundance of intercellular bridges in previtellogenic follicles suggests that they may be involved in the maintenance of dormant oocytes during periods of suspended reproductive activity and in the preparation of these oocytes for ensuing periods of intense metabolic activity associated with yolk accumulation.
Hair loss and cyst formation in hairless and rhino mutant mice
Authors: Mann Stanley J.
Published: February 2005

Structural abnormalities begin in the integument of hairless (hrhr), hairless‐rhino (hrhrrh), and rhino (hrrhhrrh) male and female mutant mice prior to the end of the first hair growth cycle. The pilary canals begin to widen and accumulate keratin and sebaceous material. During the first catagen phase the lower internal root sheath coalesces around the terminal part of the hair shaft and abnormal club hairs form. The lower part of the external root sheath fails to follow the ascending club hair and becomes stranded in the dermis. The abnormal club hairs move above their normal anchoring position and fall out of the follicle at the end of the first growth cycle. The formation of abnormal club hairs and the loss of hair probably are related to the mispositioning of the internal root sheath. Subsequent to the loss of hair there are changes in the sebaceous glands and adipose tissue, disorganization of the peripheral neurovascular system, and the formation of cysts that are associated with either the pilary canals or with epithelial units of disorganized hair follicles stranded in the dermis. Cysts arise from proliferation of epithelial tissue; sebaceous cells are not necessary for cyst formation.

Comparisons among similar and dissimilar anomalies indicate that the degree of gene action on the integument is in the following order of increased severity: hrhr, hrhrrh, and hrrhhrrh.
Effect of sodium fluoride and sodium pyruvate on palatal development in vitro
Authors: Myers Gordon S.
Published: February 2005

Explants of the embryonic rat palate have been treated by adding sodium fluoride and sodium pyruvate to the culture medium. Fluoride, at specific concentrations, causes retardation of palatal shelf growth so that fusion does not occur during the culture period. Partial or complete fusion does occur if fluoride levels are reduced.

Sodium pyruvate added to the medium advances the time of fusion of explants over that found in controls. When combined with fluoride in the medium, pyruvate can reverse the effects of fluoride on shelf growth and permit complete fusion to take place in a laige percentage of explants.

The mode of action of flucride or pyruvate under these experimental conditions has not been determined. However, the known effects of fluoride as an enzyme inhibitor must be considered.
Effect of estrogen treatment on bone cortex of the young rat
Authors: Singh I. J. , Gunberg D. L.
Published: February 2005

Thirty‐day old female rats were injected with 0.2 μg of 17‐Beta‐Estradiol daily for 30 days, and sacrificed at varying intervals. Decalcified crosssections of mandible, femur and tibia were prepared and measurements were made of: (1) number of osteons in two fields, (2) average number of lamellae per osteon, (3) average Haversian canal diameter, and (4) number of non‐Haversian (primary) longitudinal canals in two ×40 microscopic fields. Pro‐longed estrogen administration resulted in (1) earlier opening of vaginal plates, (2) lower rate of gain in body weight until treatment was stopped, (3) inhibition of linear bone growth but not of bone diameter, (4) decrease in the ratio bone‐weight/body‐weight, and (5) accelerated age changes in the aforementioned histologic variables; namely, increase in the first two and decrease in the latter two histologic measurements. Regression analyses indicated that as compared to long bones, consistently more accurate estimates of age at death could be derived from mandibular histology. It was concluded that bone microstructure is a sensitive measure of the metabolic state of the organism and the quantitative histologic techniques utilized here have important applications in diagnostic pathology, anthropology and in studies of development and aging.
The fine structure of bone in the nasal turbinates of young pigs
Authors: Fetter Arthur W. , Capen Charles C.
Published: February 2005

The three types of bone cells in the nasal turbinates had characteristic ultrastructural features. Osteoblasts were located in areas of new bone formation and had abundant endoplasmic reticulum, prominent Golgi apparatuses, numerous vesicles, and cytoplasmic processes that penetrated the adjacent osteoid. Osteocytes had variable ultrastructural characteristics. The predominant cell filled the lacuna, had few organelles, smooth plasma membranes, and was interpreted to be a mature resting osteocyte. Some osteocytes appeared to be transitional between osteoblasts and mature osteocytes. Evidence of matrix formation was seen near osteocytes with well developed organelles, whereas osteocytes with swollen mitochondria, dense bodies and irregular plasma membranes appeared to be involved with resorption of bone. Multinucleated osteo‐clasts contained numerous mitochondria and had crystals or unmineralized collagen fibrils between folds and within vacuoles of the cytoplasmic projections forming the brush border.
Ruthenium red and violet. III. Fine structure of the plasma membrane and extraneous coats in amoebae (A. proteus and chaos chaos)
Authors: Szubinska Barbara , Luft John H.
Published: February 2005

Ruthenium violet, closely related to ruthenium red, supplements the ultrastructural knowledge of the plasma membrane complex. Amoebae throughout were handled individually with braking pipettes and were exposed to ruthenium violet alive, during fixation with acrolein and OSO4, or during dehydration. Ruthenium violet was less toxic than ruthenium red but still killed the amoebae. Conventional methods reveal a filamentous layer 2000 Å thick, an amorphous layer 150 Å thick, and a typical trilaminar plasma membrane (48 Å center‐to‐center). Ruthenium violet binds to the plasma membrane, and to the extraneous coats revealing globules in the filamentous layer. The diameter of the globules decreased according to the stage of processing at which the amoebae first encountered ruthenium violet; they were 1200 Å in diameter when amoebae were alive, 600 Å in acrolein and 300 Å in dehydration. The appearance of the filamentous layer varied when ruthenium violet was replaced by very pure ruthenium red or red containing ruthenium brown (typical of commercial ruthenium red). The globules could be demonstrated without using ruthenium dyes when amoebae were treated after fixation with uranyl acetate or phosphotungstic acid. The relationship of extraneous coats of amoebae is compared with the coats and laminae of animal tissue cells.
Fine structure of the Mongolian gerbil adrenal cortex
Authors: Nickerson Peter A.
Published: February 2005

The relative weight of the Mongolian gerbil adrenal is one of the largest of any animal species. The adrenal cortex of the gerbil can be divided into three major zones and one zone located between th zona fasciculata and zona reticularis. Mitochondrial cristae of zona glomerulosa cells are plate‐like, those of the zona fasciculata are tubular whereas cristae are extensively developed and plate‐like in the zona reticularis. Lipid droplets are numerous in fasciculata cells and sparse in glomerulosa and reticularis cells. Fasciculata and glomerulosa cells contain tubules of smooth endoplasmic reticulum whereas rough reticulum predominates in reticularis and border cells. Abundant lysosomes are found in glomerulosa cells; lysosomes are aggregated beneath the cell membrane of reticularis cells. Whorls of concentric lamellae of rough endoplasmic reticulum are localized exclusively to cells in the border zone. Cells in the border zone resemble those of the reticularis because of a virtual absence of smooth endoplasmic reticulum although mitochondrial cristae are tubular and therefore similar to those of the zona fasciculata. It is suggested that cells in the border zone represent a reserve of cells which may transform into fasciculata cells upon stimulation.
Ultrastructure of the junctional complexes from the descending thin limbs of the loop of Henle from rats
Authors: Bulger Ruth Ellen
Published: February 2005

No spaces were seen within the tight junctions of descending thin limb cells of Henle's loop in rat kidney, although spaces 70 Å in diameter and larger had previously been reported in studies utilizing rabbit kidney. Colloidal lanthanum added to the fixative solutions was not able to penetrate these rat tight junctions.
Integrated actions of the four heads of quadriceps femoris: An electromyographic study
Authors: Basmajian J. V. , Harden T. P. , Regenos E. M.
Published: February 2005

From intramuscular bipolar fine‐wire electrodes in the four heads of quadriceps femoris, electromyographic recordings were made (along with electrogoniometric records) in nine normal men and women during selected postures and movements of the loaded and unloaded knee. Variation between the onset and cessation of activity between the four heads and from subject to subject was found, but the vastus medialis reflected the general pattern of activity rather than acting only terminally during extension. Rectus femoris had the shortest span of activity during extension of the knee.