bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytoplasmic bar‐like structures of alveolar type II cells: An ultrastructural study in freshly isolated cells from rat lungs
Authors: Vincent Renaud , Nadeau Denis
Published: February 2005

Bar‐like structures are tubular cytoplasmic inclusions foundin situin pulmonary epithelial type II cells of several animal species. The physiological significance and mode of formation of these inclusions are not fully established. In this paper, we describe bar‐like structures as found in freshly isolated type II cells from rat lungs. Pulmonary cells were dissociated from the tissue with elastase and separated on a discontinuous density gradient of Percoll. The complete isolation procedure yielded 17 × 106type II cells per animal (purity = 80%). Either from the crude cell suspensions or the purified preparations, only a small fraction of the type II cell population harbored the inclusions (> 5%). It is shown that the bounding membranes of the bar‐like structures can derive from the endoplasmic reticulum, the nuclear membrane, or the Golgi apparatus. Occasional connections with lamellar bodies were observed, and different levels of complexity in the bar‐like structures were also found. The apparent rigid conformation and the orientation of the bar‐like structures were taken as evidence for a role of the cytoskeleton in their formation. Because the inclusions do not appear to be new organelles or cellular structures performing a specific function, we propose that their formation may be a transient and limited cellular event in normal cells. However, the stabilization and the generation of the osmiophilic structures, as well as their overproduction, may reflect alterations of the normal physiology of the type II cells.
Radioautographic tracing of 3H‐proline in the endodermal cells of the parietal yolk sac as an indicator of the biogenesis of basement membrane components
Authors: Mazariegos Mario R. , Leblond C. P. , van der Rest Michel
Published: February 2005

The biogenesis of basement‐membrane components was investigated in the endodermal cells of the rat parietal yolk sac in 12.5‐day pregnant rats; 3H‐proline was injected into conceptuses. After various time intervals, the parietal yolk sac, including endodermal cells and the associated Reichert's membrane, was removed and processed for electron‐microscopic radioautography. Silver grains were counted over endodermal cell organelles and Reichert's membrane.

At 2 and 5 min after 3H‐proline injection, endodermal cells showed heavy labeling in rough endoplasmic reticulum (rER). Silver grain density over the rER decreased from 2 to 20 min and then remained at a plateau. Grain density was moderate over the Golgi apparatus initially but rose to a peak at 2 hr and decreased by 4 hr and later. Grain density was negligible over secretory granules at 2 and 5 min and increased moderately with time to reach a maximum at 8 hr. Thus, radioautographic peaks occurred sequentially in rER, Golgi apparatus, and secretory granules. By 4 hr and later, silver grains accumulated over Reichert's membrane. These results indicated that endodermal cells incorporated labeled proline into substances which were processed from the rER through the Golgi apparatus, transported from there to the cell surface by secretory granules, and released for export to Reichert's membrane.

To clarify the nature of the exported substances, the amount of label present in proline and hydroxyproline residues after 3H‐proline injection was measured in Reichert's membrane with or without the associated endodermal cells. Within the cells, 61.8% of the labeled proteins were classified as “sedentary” and 38.2% as “exportable.” Of the label exported to Reichert's membrane, 66.3% consisted of type IV collagen and the rest of other basement‐membrane components.

The results obtained with this model suggest that basement‐membrane proteins, including type IV collagen, are elaborated by the associated cells through the classical pathway: rER‐Golgi apparatus‐secretory granules.
Tridimensional architecture of the Golgi apparatus and its components in mucous cells of Brunner's glands of the mouse
Authors: Rambourg A. , Clermont Y. , Hermo L. , Segretain D.
Published: February 2005

The three‐dimensional structure of the Golgi apparatus and its components has been analyzed in thin and thick sections of mucous cells of mouse Brunner's glands by using low‐ and high‐voltage electron microscopes and a stereoscopic approach. In thick sections of glands impregnated with osmium or treated to detect nicotinamide adenine dinucleotide phosphatase (NADPase) or thiamine pyrophosphatase (TPPase) activity, the Golgi apparatus appeared, at low magnification, as a continuous network located in the supranuclear region. At higher magnifications and in thin sections of tissue postfixed with reduced osmium and stained with lead citrate or treated to demonstrate phosphatase activity, the following components were observed: (1) on the cis‐face of the Golgi stacks, an osmiophilic tubular network referred to as the cis‐element; (2) a cis‐saccular‐compartment composed of a distended porous saccule slightly reactive for NADPase and three or four underlying NADPase‐positive, flattened, poorly fenestrated saccules; (3) a trans‐saccular‐compartment consisting of four to six TPPase‐positive saccules or sacculo‐tubular elements, prosecretory granules, and “peeling off” trans‐tubular networks.

The saccules of the cis‐compartment were often perforated by large pores in register. The cavities thus formed in the stacks were called wells and were pan‐shaped with a mouth directed toward the cis‐face of the stacks and a bottom closed by TPPase‐positive saccules. The wells always contained 80‐nm vesicles. The saccules of the trans‐compartment were involved in the formation of secretory granules according to the following proposed sequence of transformation. The secretion product appeared initially as a granular material evenly distributed throughout a slightly distended, poorly fenestrated saccule. These saccules appeared to transform into fenestrated elements with irregular pores and with parts of them taking on the appearance of a tubular network; they were thus referred to as sacculotubular elements. The secretory material initially distributed throughout these elements accumulated in nodular dilatations randomly distributed along the tubular portions of the elements. The dilatations, considered as prosecretory granules, increased in size as they drained the secretory material from the rest of the sacculotubular elements. Such prosecretory granules, large and irregular in shape, “peeled off” from the stacks of saccules with residual saccular or tubular structures still attached to them, some of the latter forming trans‐tubular networks. The prosecretory granules detached from such membranous residues, condensed, and finally transformed into spherical secretion granules.
Myocardial capillaries in the fetal and the neonatal rat: A morphometric analysis of the maturing myocardial capillary bed
Authors: Porter Glyn A. , Bankston Patrick W.
Published: February 2005

Developing myocardial capillaries from 16‐day‐gestation fetus to adult undergo several morphological changes including a thinning of the lateral extensions of the capillary endothelial cells, the formation of a basal lamina, and an increase in the number of plasmalemmal vesicles. A decrease in the extracellular space, an increase in the number of capillaries, and a decrease in the capillary diameter were also observed during the developmental period. In view of these ultrastructural changes, a morphometric analysis was made on the developing myocardial wall to demonstrate specific quantitative changes. The volumes which were occupied by capillary endothelial cells, capillary lumina, extracellular space, and myocardial myocytes within a reference volume of myocardium were measured; and we found that 8% of the reference myocardial volume was occupied by capillary endothelial cells, 85% was occupied by myocardial myocytes, 4% was occupied by capillary lumina, and, except for a significant change in extracellular space at 16 days gestation, 3% was occupied by extracellular space. Each volume ratio was found to be nearly constant throughout the studied period. In contrast to this constancy in the volume ratios, other parameters which were measured demonstrated significant changes during the developmental period studied. These overall changes include a 135% increase in capillary density, a 63% increase in luminal surface area of capillary endothelial cells, a 24% decrease in capillary diameter, a 12% decrease in diffusion distance, and a 35% decrease in the diameter of the erythrocyte population. The decrease in capillary diameter occurs concomitantly with and may be correlated to the decrease in erythrocyte diameter. Also, the increasing number of capillaries offset the effect of the decrease in capillary diameter, resulting in constant volume ratios. This constancy in the volumes of the measured myocardial compartments during development, despite the considerable changes in morphology and in the other measured parameters which are occurring in the myocardial wall, can be interpreted to mean that some functional constraints are operating to maintain capillary‐to‐myocardium volume ratios within very narrow limits.
Splenic hypertrophy and extramedullary hematopoiesis induced in male Syrian hamsters by short photoperiod or melatonin injections and reversed by melatonin pellets or pinealectomy
Authors: Vaughan M. K. , Hubbard G. B. , Champney T. H. , Vaughan G. M. , Little J. C. , Reiter R. J.
Published: February 2005

Adult male Syrian hamsters either placed in a short photoperiod alone or kept in a long photoperiod and given daily afternoon injections of the pineal indole melatonin (25 μg) exhibited splenic hypertrophy and extramedullary hematopoiesis in addition to a marked regression in testicular weight. The testicular regression as well as the changes in spleen weight and histology could be prevented if the animals in short photoperiod were either pinealectomized or implanted subcutaneously with a pellet containing 1 mg melatonin. Female Syrian hamsters given afternoon injections of melatonin for 7 or 12 weeks had ovaries devoid of corpora lutea; additionally, these animals had reduced relative spleen weights compared to the control animals. In conclusion, it is apparent that spleen weight varies with the functional status of the gonads. Splenic hypertrophy accompanied by pineal‐induced testicular regression in males may be related to splenic extramedullary hematopoiesis.
Ultrastructure of neural crest formation in the midbrain/rostral hindbrain and preotic hindbrain regions of the mouse embryo
Authors: Nichols David H.
Published: February 2005

In the mouse embryo, neural crest mesenchyme associated with the first and second pharyngeal arches escapes from the epithelium that forms the tips of the midbrain/rostral hindbrain and preotic hindbrain neural folds. To investigate the ultrastructure of crest formation, embryos with four to eight pairs of somites were processed for transmission electron microscopy. In the earliest event related to crest formation, crest precursors in the midbrain/rostral hindbrain elongated and moved all or most of their contents to the basal region of the epithelium. Elongation was probably mediated by apical bands of micro‐filaments and longitudinally oriented microtubules. Elongated cells then relinquished apical associations while nonelongated cells maintained those associations and withdrew from the basal lamina. This resulted in an epithelium stratified into apical and basal (crest precursor) layers. The coalescence of enlarging extra‐cellular spaces opened a delaminate gap between the two layers. Additional crest precursors entered this gap from the apical layer. From the time crest precursors began moving basally, some formed microfilament‐ and/or microtubule‐containing processes, which penetrated the basal lamina. Some of these cells moved their contents into the larger, microtubule‐containing processes, perhaps thereby escaping from the epithelium. Soon after elongating cells appeared, the basal lamina beneath the epithelium began to degrade in a pattern unrelated to process formation. This ultimately resulted in disruption of the lamina, dispersal of the basal layer of the epithelium, and release of the crest precursors in the delaminate gap. Once crest formation was complete, the apical layer reformed a basal lamina on a patch‐by‐patch, cell‐by‐cell basis. In the preotic hind‐brain, elongating crest precursors apparently forced their basal faces through the basal lamina and then relinquished apical association to escape. As a result, the lamina was disrupted before the epithelium could stratify, and enlarged extracellular spaces appeared among mesenchymal cells rather than creating a delaminate gap. The failure of elongation to disrupt the basal lamina in the midbrain/rostral hindbrain and its success in the preotic hindbrain might be due to less‐vigorous, less‐concerted elongation in the midbrain/rostral hindbrain or to earlier, more rapid degradation of the lamina in the preotic hindbrain.
Ultrastructural localization of heparan sulfate and chondroitin sulfates associated with granulopoiesis in embryonic chick bone marrow
Authors: Sorrell J. Michael , Voci Matthew , Weiss Leon
Published: February 2005

Sulfated glycoconjugates were ultra‐structurally localized within embryonic chick marrow by using the high iron diamine–silver proteinate stain. Stain was concentrated in the extravascular, granulopoietic compartment, indicating that granulopoiesis, but not erythropoiesis, proceeded in a highly sulfated environment. It was likely that most of the stainable material represented sulfated proteoglycans since staining was abrogated by predigesting tissue with enzymes and other treatments known to degrade specific glycosaminoglycan chains. Chondroitinase/hyaluronidase digestion resulted in the removal of most of the stainable material associated with the extracellular matrix and a portion of the stainable material associated with fibroblastic cell surfaces. Unaffected material lay in close proximity to fibroblastic cell membranes. Heparitinase/heparinase digestion had essentially the opposite effect. Sulfated material associated with matrix components was largely unaffected, but the fibroblastic plasmalemmal material was now absent. These results suggest that there are at least two categories of sulfated proteoglycans in the granulopoietic compartment, each differentially distributed. The plasmalemmal material likely represented heparan sulfate which in this tissue appeared to be associated in a uniform layer with fibroblastic stromal cell membranes and not with blood or endothelial cell membranes. Material identified as chondroitin sulfates was found within patches of amorphous matrix that was located on fibroblastic stromal cell surfaces and that was interspersed with fibrils in the extracellular matrix. Chondroitin sulfates were sparsely distributed on granulocytic cell surfaces.
Opossum adrenal medulla: II. Differentiation of the chromaffin cell
Authors: Spagnoli Daniel B. , Frederickson Richard G. , Robinson Robert L. , Carmichael Stephen W.
Published: February 2005

The ultrastructure of the opossum adrenal medulla was examined in its postnatal development. Maturation of chromaffin cells and genesis of chromaffin vesicles were of particular interest. The primitive sympathetic cell was seen to contain few organelles with no apparent polarity. Initial pheochro‐moblasts contained more organelles with some polarity. Endoplasmic reticulum and the Golgi complex increased as the pheochromoblasts matured, which suggested increased synthetic activity. Structures resembling Golgi/endoplasmic reticulum/lysosome (GERL) systems were seen in the pheochromoblasts. It is suggested that some of the components of the chromaffin vesicle may be processed by the GERL while others come directly through the Golgi complex. It is stressed that the developing pheochromoblast in the opossum presents an interesting model in which to study the genesis of the chromaffin vesicle.
Projection of cervical dorsal root fibers to the medulla oblongata in the brush‐tailed possum, Trichosurus vulpecula
Authors: Culberson James L.
Published: February 2005

This study describes the projection of cervical spinal afferent nerve fibers to the medulla in the brush‐tailed possum, a marsupial mammal. After single dorsal roots (between C2 and T1) were cut in a series of animals, the Fink‐Heimer method was used to demonstrate the projection fields of fibers entering the CNS via specific dorsal roots. In the high cervical spinal cord, afferent fibers from each dorsal root form a discrete layer in the dorsal funiculus. The flattened laminae from upper cervical levels are lateral and those from lower cervical levels are medial within the dorsal columns. All afferent fibers at this level are separated from gray matter by the corticospinal fibers in the dorsal funiculus. All cervical roots project throughout most of the length of the well‐developed main cuneate nucleus in a loosely segmentotopic fashion. Fibers from rostral roots enter more lateral parts of the nucleus, and fibers from lower levels pass to more medial areas; but terminal projection fields are typically large and overlap extensively. At more rostral medullary levels, fibers from all cervical dorsal roots also reach the external cuneate nucleus. The spatial arrangement here is more complex and more extensively overlapped than in the cuneate nucleus. Rostral cervical root fibers reach ventral and ventrolateral areas of the external cuneate nucleus and continue to its rostral pole; more caudal root fibers project to more dorsal and medial regions within the nucleus. These results demonstrate that projection patterns of spinal afferents in this marsupial are similar to those seen in the few placental species for which detailed data concerning this system are available.
Decidual cells in the human ovary at term: II. Morphometric analysis of cytoplasmic processes and organelles
Authors: Herr John C. , Fares Nagui H. , Banhawy Mohammed A.
Published: February 2005

Morphometric analysis of human ovarian decidual cells was performed with a Videoplan computer, and mean values were established for the area and perimeter of cellular processes and organelles. Two‐hundred forty electron micrographs representing 160 cells were analyzed. The mean decidual cell area was 218.7 μm2 of which 34.5 μm2 was occupied by the nucleus (15.8% of the cytoplasmic area); the nucleus contained 1.74 μm2 of nucleolar material (0.8%). The endoplasmic reticulum occupied 13.63 μm2 (6.2%). Mitochondria occupied 7.3 μm2 (3.3%) and the Golgi network 5.49 μm2 (2.5%). Decidual secretory bodies occupied 0.91 μm2 (0.42%) and cytoplasmic processes 1.89 μm2 (0.94%). The remainder of the cytoplasm, containing inclusions and cytoskeleton, represented 71% of the cell area. Perimeter measurements indicated an average decidual cell was surrounded by 87.8 μm of plasma membrane. The mean nuclear membrane measured 28.3 μm (representing 32.3% of the plasma membrane, pm, or 4.1% of total cellular membranes, cm). Outer mitochondrial membranes measured 156.6 μm (178% pm, 23.5% cm); endoplasmic reticulum membranes measured 350.3 μm (400% pm, 52.6% cm); Golgi membrane measured 30.77 μm (35% pm; 4.5% cm) and membrane surrounding secretory bodies measured 9.8 μm (11.2% pm; 1.4% cm). A mean of 280 secretory bodies per ovarian decidual cell was calculated. The plasma membranes of evaginated cytoplasmic processes represented 22.3% of the total pm (19.6 μm or 2.9% cm). A mean of seven such processes was observed per 87.8 μm of plasma membrane (160/cell). These morphometric data provide a baseline for comparisons of human ovarian decidual cells with uterine decidua, in vivo and in vitro, as well as with decidual cells of other species.
Ultrastructure of cardiocyte degeneration and myocardial calcification in the dystrophic hamster
Authors: Burbach James A.
Published: February 2005

The myocardium of the Bio 14.6 cardiomyopathic hamster was examined with the electron microscope to identify cellular and organelle changes during the acute lesioning stage, a period typified by concomitant cardiocyte destruction and calcium elevation. Most cardiocytes retained their normal histologic and ultrastructural features, but scattered foci of altered and necrotic cells were observed in association with degenerative calcifying lesions. Prenecrotic alterations of myocytes included cellular edema; varying degrees of distension of sarcoplasmic reticulum and T‐tubules; contraction bands and other myofibrillar abnormalities; mitochondrial clustering and hyperplasia; a wide spectrum of mitochondrial changes such as altered sizes, shapes, and cristal patterns, and increases in the number and size of osmiophilic matrix inclusions. Morphologic features consistent with substantial calcium excess were not observed in most altered but prenecrotic cells. Instead, calcium deposition within extruded mitochondria and upon degenerating organelle debris was observed only after cardiocyte disruption. Some calcifying cell remnants were phagocytized by macrophages, whereas large calcified plaques and other deposits remained in the interstitium. Mitochondrial calcification in vascular smooth muscle cells and fibroblasts was evident in highly calcified lesions. These observations suggest that most of the morphologically identifiable calcium deposition present in this cardiomyopathy results from secondary calcification subsequent to sarcolemmal disruption.
Biological time and the effects of hydroxyurea on DNA synthetic activity of bone marrow and tumor cells in mice bearing the Ehrlich ascites carcinoma
Authors: Burns E. Robert
Published: February 2005

The objective of this experiment was to attempt to induce, with hydroxyurea (HU), significant quantitative differences in the level of DNA‐synthetic activity (DNA‐SA) between a neoplastic cell population (the Ehrlich ascites carcinoma or EAC) and bone marrow in the same animal. Mice bearing a 5‐day‐old EAC were standardized to and kept on an LD 12:12 cycle (light 0600–1800 hr). They were treated with 500 mg/kg HU at 0500 hr (23 hr after lights on, or HALO) or at 1700 hr (11 HALO). DNA‐SA was determined by liquid scintillation counting of 3H‐thymidine incorporation into chemically isolated DNA. DNA‐SA in bone marrow and EAC cells was monitored over the next 60 hr with subgroups of ten mice each killed every 3 hr beginning 3 hr after treatment with HU. The circadian system of the host influenced the response of the bone marrow to HU; i.e., the response to HU administered at 0500 hr was different both qualitatively and quantitatively from that for HU given at 1700 hr. Comparisons of DNA‐SA in bone marrow and EAC from the same animal revealed time points after treatment with HU when DNA‐SA in the EAC was high, but DNA‐SA in bone marrow was low. These differences in the level of DNA‐SA between a tumor cell population and bone marrow should be of therapeutic value; i.e., executor doses of anti‐DNA‐SA drugs such as cytosine arabinoside could be given at that point in time after treatment with HU when DNA‐SA in the tumor was high, but DNA‐SA in the bone marrow was low.
Estrogen‐induced tumors: Changes in the vasculature in two strains of rat
Authors: Schechter Joel , Ahmad Nazir , Elias Kathleen , Weiner Richard
Published: February 2005

The influence of estrogen on the vasculature of the pars distalis has been studied in two strains of rat that differ in estrogen responsiveness. (Fischer 344 rats are highly estrogen‐responsive in comparison to Sprague‐Dawley rats.) Ovariectomized adults were implanted with silastic capsules containing 17 β‐estradiol benzoate. Control and experimental animals were sacrificed 10 and 20 days after implantation of the silastic capsules.

Pituitary weights and plasma prolactin were elevated dramatically in estrogen‐treated Fischer rats in comparison to more moderate increases in Sprague‐Dawley rats. Although both strains exhibited the hypertrophy of mammotrophs expected after estrogen stimulation, the vasculature in Fischer rats was dramatically altered from normal. The pars distalis of the 20‐day, estrogen‐treated Fischer rats contained well‐formed arteries. In addition, capillaries frequently were disrupted, contributing to the formation of hemorrhagic lakes unlined by an endothelium. Even in intact capillaries, basal laminae delimiting the pericapillary spaces often were disrupted or absent. Perivascular connective tissue cells were prominent within the perivascular spaces and often contained rumerous, large lysosomal dense bodies as well as clusters of small dumbbell‐shaped bodies. These granule clusters also were apparent adjacent to the perivascular space within parenchymal cells, most frequently within follicular cells.

The vasculature of Sprague‐Dawley rats maintained a more normal appearance after estrogen treatment, although perivascular connective tissue cells did appear activated and basal laminae delimiting the pericapillary spaces were disrupted occasionally. However, no capillaries were disrupted, nor were any hemorrhagic lakes evident, and no arteries were present.

The results indicate that in some strains of rat, estrogen may influence the integrity of the pars distalis vasculature, including the possibility of stimulating vascular reorganization and arteriogenesis. If stimulation of arteriogenesis decreases normal hypothalamic inhibition of mammotrophs, this could be an important factor underlying the formation of prolactinomas.
Effects of estradiol and progesterone on accumulation of relaxin‐ and carbohydrate‐containing granules in endometrial gland cells of the guinea pig
Authors: Larkin Lynn H. , Ogilvie Susan , Wubbel Loretta , Welch David E.
Published: February 2005

Guinea pigs were spayed and given various regimens of injections of estradiol and progesterone. The following were monitored in each animal: pubic separation (relaxin stimulation), resorption of the vaginal membrane (estrogen priming), and the presence of PAS‐positive granules and/or relaxin in endometrial gland cells (EGC). Injections of estradiol alone resulted in resorption of the vaginal membrane, accumulation of PAS‐positive granules in EGC of all animals, and accumulation of relaxin in EGC of two of four animals; but they did not cause pubic separation. Progesterone injections did not result in resorption of the vaginal membrane, separation of pubes, or accumulation of PAS‐positive granules; however, one of three animals demonstrated a few EGC that contained relaxin. Animals that received both estradiol and progesterone exhibited PAS‐positive granules and relaxin in EGC as well as separated pubes, but did not have resorbed vaginal membranes.

Upon examination with the electron microscope, EGC from animals that received estradiol alone exhibited remarkable numbers of secretory granules that contained a carbohydrate‐rich material. Secretory granules were not prominent in EGC from animals that received progesterone alone. Estradiol and progesterone injections resulted in accumulation of secretory granules in EGC that contained relaxin and a carbohydrate‐rich material.

The observations that estradiol and progesterone induce relaxin production in EGC support the hypothesis that uterine relaxin plays an important role in pregnancy and/or parturition in the guinea pig.
Ultrastructure of complex carbohydrates of rodent and monkey ependymal glycocalyx and meninges
Authors: Rhodes Roy H.
Published: February 2005

The surfaces of the brain offer metabolic and mechanical support to the underlying parenchyma. Mouse, rat, and monkey brains were fixed by immersion in a glutaraldehyde fixative or glutaraldehyde with cetylpyridinium chloride, followed by block staining for complex carbohydrates using alcian blue with OsO4 postfixation, or OsO4 postfixative solution containing ruthenium red, or alcian blue and then ruthenium red‐OsO4 treatment. The ependyma in these species had a glycocalyx extending into the ventricular fluid as a finely filamentous network when stained with alcian blue or with alcian blue followed by ruthenium red‐OsO4. Mice in the middle age range had stained material in this glycocalyx resembling the hyaluronic acid reported in the ocular vitreous body. Similar material was seen in the arachnoidal space of these mice and in the inner connective tissue matrix of the dura mater. Both the mouse and monkey had a cell‐free zone, termed the inner dural matrix zone, between the thick fibrous dura and its innermost cellular layer. This zone contained filamentous and globular alcian blue‐stained material. The complex carbohydrates of the mouse ependymal glycocalyx and inner dural matrix zone underwent changes developmentally. Aged rats were injected intraventricularly with latex beads, which, along with extravasated erythrocytes, were seen to adhere to the ependymal glycocalyx. A similar adhesion of erythrocytes was seen in the mouse and monkey ependymal glycocalyx and in the filamentous network of the mouse and monkey inner dural matrix zone.

The ependymal glycocalyx, formed in part of complex carbohydrates, is much thicker than previously demonstrated. Some activities related to the ependymal lining of the ventricles, including the movement of cells or particles, the penetration of metabolites or serumprotein fractions (e.g., immunoglobulins), and cell‐surface hydration, probably depend in part on complex carbohydrates that provide a sticky, electrically negative, hydrophilic environment. The complex carbohydrates in the inner dural matrix zone might provide mechanical buffering. Complex carbohydrates in the arachnoidal space may help to maintain a loose tissue that needs not only to be hydrated, but also to be open enough to provide cerebrospinal fluid circulation.
Postnatal development of the ovarian bursa of the golden hamster (Mesocricetus auratus): Its complete closure and morphogenesis of lymphatic stomata
Authors: Shinohara Harumichi , Nakatani Toshio , Matsuda Takeshi
Published: February 2005

The golden hamster ovarian bursa was studied by light and electron microscopy to clarify the process of its complete closure and the development of lymphatics that leads to morphogenesis of stomata. The results were as follows. (1) The bursa completely closed at 9 days of age primarily due to development of the mesotubarium superius. (2) With the closure, the ovary and bursa became closely apposed, and most of the original bursal cavity disappeared. (3) Between 9 and 12 days of age U‐shaped folds of the bursal mesothelium began to invade the connective tissue of the bursa. (4) Widening of the internal angle of the U‐shaped folds contributed to reappearance of the bursal cavity, and thus separation of the bursa from the ovary. It also contributed to future geometrical proximity of lymphatics to the cavity of the bursa. (5) The separation of the bursa from the ovary began as early as 12 days of age in the cephalic half of the bursa. It occurred remarkably late in the caudal half. Juxtaposition of the window portion of the bursa to the ovary remained in some adult animals. (6) Development of lymphatics in the cephalic half of the bursa was divided into two stages, before and after days 21–24 of life. In the first stage, lymphatics grew in the submesothelial connective tissue, and the framework of lymphatics was formed. In the second stage, lymphatics extended small branches to form the submesothelial plexus or lymphatic lacuna. (7) Intercellular junctions between contiguous lymphatic endothelial cells were mostly tight and desmosomelike. Open junctions were, if they occurred at all, rare. (8) A smooth‐surfaced area lined with the lymphatic endothelium was found in the bursa on day 27 of life, before the initiation of ovulation. Valvelike stomal orifices were absent before the initiation of ovulation and extremely rare even after the first ovulation. They were commonly present in the bursae after the fourth ovulation, however.

The process of complete closure of the ovarian bursa is very complex and may be related to the later development of the bursal mesothelium and lymphatics. Some liplike stomal orifices are of purely developmental origin. However, all valvelike stomal orifices are assumed to be formed as a result of damage to the bursal mesothelium, as well as to the submesothelial connective tissue and lymphatics, by repetition of ovulation. It is possible that liplike stomal orifices may be formed in the process of repairing the damage.
Immunohistochemical demonstration of keratins in the cysts of thyroid glands, parathyroid glands, and C‐cell complexes of the dog
Authors: Kameda Yoko
Published: February 2005

Cyst structures were often detected in and around thyroid glands of the dog. The present study revealed the frequency of occurrence, the light microscopic features, and the immunoperoxidase reactions to anti‐keratin and anti‐ldS‐thyroglobulin antisera of each cyst located in parathyroid III, parathyroid IV, thymus IV, C‐cell complexes, and thyroid parenchyma from 112 dogs. In each location, cysts showed characteristic features. In parathyroid III, the cysts were covered with single or pseudostratified epithelium composed of ciliated cells; whereas in parathyroid IV they were covered with keratinizing stratified squamous epithelium. In C‐cell complexes, small cysts lined with small packed cells were predominant, and large cysts lined with single cuboidal cells or stratified squamous cells were also present. In thymus IV located in the close vicinity of parathyroid IV, cyst epithelium consisted of several types of cells showing variable futures. In thyroid parenchyma, there were several types of cysts: some were covered with ciliated columnar cells, and others were covered with two or multilayers of small packed cells or cuboidal cells. In spite of these differences in appearance of the cysts located in different tissues, all their epithelia were immunoreactive to the keratin antisera, except for small cysts in C‐cell complexes, which were regarded as immature structures. Thus, the presence of keratin filaments in epithelial cells seems to be a characteristic feature of all cysts. The lumens of each cyst contained variable amounts of amorphous materials, which showed colloid‐like, flocculent, foamy, and granular features and were periodic acid‐Schiff‐positive in variable degrees, from weak to intense. Although the lumenal contents of the cysts in parathyroid III revealed no immunoreactivity for 19S‐thyrogIobulin, those in thyroid parenchyma, C‐cell complexes, parathyroid IV, and thymus IV reacted strongly with the 19S‐thyroglobulin antiserum.
Morphological study of sarcoplasmic reticulum in the atrioventricular node and bundle cells in guinea pig hearts
Authors: Tomita Yoshtfumi , Ferrans Victor J.
Published: February 2005

The osmium‐ferrocyanide method for staining of the sarcoplasmic reticulum (SR) was used for a morphological investigation of the various components of the SR in the atrioventricular node and bundle (AVNB) cells of guinea pig hearts. On the basis of light microscopic observations, the AVNB tissue in guinea pig hearts can be divided into five regions: atrionodal junction, midnode, proximal bundle, distal bundle, and bundle branches. Electron microscopic observations revealed two types of junctional SR (j‐SR) saccules in the cells from all the regions of AVNB tissue. One is similar to that seen in the working cardiac cells, i. e., flattened saccules with junctonal granules. The second type is dilated and contains electrondense granular material throughout its lumen. The flattened type is seen more often than the dilated type in atrionodal junctional cells and midnode cells, whereas the dilated type occurs more often in distal bundle cells and bundle branch cells. In most cells from the atrionodal junction and midnode regions, the j‐SR saccules are apposed more often to sarcolemmal areas associated with nonspecialized regions of intercellular junctions than to other sarcolemmal areas. This distribution was not found in the distal bundle and bundle branch cells. Free SR tubules around the myofilament bundles are poorly developed in the midnode cells, generally in accord with the extent of development of myofibrils. Z‐tubules are found in cells from all regions but are poorly developed in midnode cells. Corbular SR vesicles are found in cells from all the regions of AVNB tissues but are rare in midnode cells. Thus, each of the regions in the AVNB tissue has a different, characteristic distribution of SR components. Because of their possible relationship to the regulation of the intracellular concentrations of calcium, these differences in SR morphology may contribute to the diverse physiological properties of the different regions of the AV node and bundle.
Radioautographic comparison of RNA synthesis patterns in the epithelial cells of mouse pyloric antrum following 3H‐uridine and 3H‐orotic acid injections
Authors: Bissonnette R. , Leblond C. P. , Lee E. R. , Paiement J.
Published: February 2005

RNA synthesis was examined in the epithelial cells of the mouse pyloric antrum using radioautography 20 min after injection of either 3H‐uridine or 3H‐orotic acid. The epithelium of the mouse antrum was known to invaginate into blind tubular units composed of mucous cells arranged from base to lop into a gland, an isthmus, and a pit. These were subdivided into segments and, after radioautography, silver grains were counted over cell nuclei in each segment.

Following 3H‐uridine injection, silver grains were present over all nuclei but were more abundant over those of the isthmus than of the gland or the pit. When nuclei were examined in the electron microscope, nucleoplasmic as well as nucleolar silver grains were more numerous in the isthmus than in the pit or gland.

Following 3H‐orotic acid injection, silver grains were again present over all nuclei; but maximal incorporation appeared to be in pit cell nuclei where, by electron microscopy, it was mainly assigned to the nucleoplasm. When the incorporation was calculated per whole nucleus, however, it was less in pit cell than in isthmal cell nuclei. Even so, the proportion of label in pit cell nuclei was much greater than after 3H‐uridine injection.

The interpretation of these findings is based on the fact that isthmal cells are immature, whereas cells migrating from the isthmus to become gland or pit cells show increasing differentiation. The immature cells of the isthmus incorporate! both uridine and orotic acid more effectively than do the differentiated cells of pit and gland. Since silver grain counts over nuclei provide an index of the rate of RNA synthesis, this synthesis proceeds more actively in the isthmus than in the pit or gland. This is true of ribosomal RNA synthesis, as shown by nucleolar grain counts, and of other RNA's synthesis, as shown by nucleoplasmic grain counts. It seems, however, that while uridine is involved in the synthesis of all types of RNA, orotic acid is mainly implicated in the synthesis of the heterogeneous UNA from which the messenger RNA arises.
Cytochemical localization of tartrate‐resistant acid phosphatase, alkaline phosphatase, and nonspecific esterase in perivascular cells of cartilage canals in the developing mouse epiphysis
Authors: Cole Ada A. , Wezeman Frederick H.
Published: February 2005

Cytochemical localization of tartrate‐resistant acid phosphatase (TRAP), tartratc‐sensitive acid phosphatases (TSAP), alkaline phosphatase, and nonspecific esterase was used to characterize perivascular cells within cartilage canals. In the distal femoral epiphyses of 5‐ to 7‐day‐old mice, three stages of canal development can be distinguished, and at each developmental stage different perivascular cells were present with morphological characteristics of degradative cells. Vacuolated cells resembling macrophages, fibroblastic cells, and chondroclasts were present adjacent to the matrix in superficial, intermediate, and deep canals, respectively. In order to characterize these perivascular cells cytochemically, nonspecific esterase and TSAP staining was used to identify macrophages, alkaline phosphatase staining was used to identify fibroblastic cells, and TRAP staining was used to identify chondroclasts. There were no cells present in the canals at any developmental stage that were positive for TSAP or strongly positive for nonspecific esterase, placing doubt on the identity of the vacuolated cells as macrophages. Alkaline phosohatase‐positive perivascular cells were present in the intermediate and deep canals adjacant to matrix containing alkaline phosphatase‐positive chondrocytes. These alkaline phosphatase‐positive cells were found in the same location within canals as the fibroblastic cells. Tartrate‐resislant acid phosphatase was localized in chondroclasts at the tips of deep canals but was not confined exclusively to chondroclasts. Except for the very early stage of canal development prior to chondrocyte hypertrophy, TRAP‐positive cells were present at the tips of superficial and intermediate canals as well as at the tips of the deep canals. Additionally, the presence of TRAP in chondrocytes with in the growth plate, in chondrocytes within the epiphyseal cartilage near some canals, and in perichondrial cells suggests that TRAP is associated with matrix degradation in the cartilage.
Three‐dimensional presentation of the fibroblast progenitor compartment in the periodontal ligament of the rat incisor
Authors: Michaeli Y. , Weinreb M. , Barad A. , Steigman S.
Published: February 2005

The purpose of this study was to determine the shape, size, and spatial configuration of the fibroblust progenitor compartment (PC) of the tooth‐related periodontal ligament (PDL). Five albino rats (weight 200 gm) were killed 1 hr following intraperitoneal injection of 3H‐thymidine. The incisors were decalcified, embedded in glycol‐methacrylate, and sectioned serially, perpendicularly to the long axis of the tooth. Ten 2‐μm‐thick sections along each tooth were selected, processed autoradiographically, and the distance from the apex measured. Labeled and unlabeled fibroblasts were counted in 8 × 80‐μm consecutive layers. Cell density (CD) and labeling index (LI) were plotted on a three‐dimensional system of coordinates depicting the directions: apex to incisal edge, cementum to bone, and cemento‐enamel junction (CEJ) to lingual tooth surface.

The CD along the tooth was constant, except at 2–6 mm distant from the apex, where it was significantly higher. The highest concentration of cells around the tooth was in the 20‐μm region adjacent to the cementum. The PC on the mesial arid lateral tooth sides extended 1–4 mm from the apex, with the LI peak (6.5%) occurring at 2 mm. The PC on the lingual tooth side was located at 2‐G mm from apex, peaking (14%) at 4 mm. On the cemenuim‐bone coordinate, the PC extended to about 50 μm from the cementum on all sides, the LI peak appearing at a distance of 20–40 μm from the tooth. The LI was consistently higher on the lingual side than on the mesial and lateral aspects.
Sequence of development of innately regenerated growth‐plate cartilage in the hindlimb of the neonatal rat
Authors: Libbin Richard M. , Weinstein Martin
Published: February 2005

It has long been appreciated that the neonatal rat can regenerate the distal femoral growth‐plate. Earlier descriptions of this process pointed to the age of the rodent and level and angle of amputation as significant modifiers of the regeneration process; but none identified the origin of the chondrocytes forming the growth‐plate regenerate, nor described the time course and significant milestones of the process. Examination of these issues constitutes the objective of the present report. Fifty‐four male, outbred albino rats sustained low femoral (48 rats) or midtibiofibular (six rats) hind‐limb amputations when ten to eleven days old. They were killed after 0, 1, 2, 4, 7, 14, 22 or 29 postoperative days; and their amputation stumps were sectioned longitudinally. Twenty‐four hr after amputation, the distal femoral periosteum was thickened and metachromatic regions were observed forming within it. Intraperiosteal cartilage was observed by the end of the second postoperative day in four of six limb stumps and, during the following week, expanded considerably in volume. Regenerated growth‐plate cell architecture was recognized within the enlarging cartilage mass by the end of the second week; and, by the end of the fourth postoperative week, the regenerating growth‐plate region had achieved considerable architectural maturity.
Observations on the anatomy of the stomach and duodenum of the bowhead whale,Balaena mysticetus
Authors: Tarpley Raymond J. , Sis Raymond F. , Albert Thomas F. , Dalton Leslie M. , George John C.
Published: February 2005

Gastric and cranial duodenal structure of the bowhead whale (Balaena mysticetus) was examined grossly and microscopically. The stomach was arranged in a series of four compartments. The first chamber, or forestomach, was a large nonglandular sac. lined by a keratinized stratified squamous epithelium. It was followed by the fundic chamber, a large, somewhat globular and entirely glandular compartment. At the entrance of the fundic chamber, a narrow cardiac gland region could be defined. The remaining onucosa of the chamber contained the proper gastric glands. A narrow, tubular connecting channel, the third distinct gastric division, was lined by mucous glands and joined the fundic chamber with the final stomach compartment, or pyloric chamber. This fourth chamber was also tubular and lined by mucous glands but was of a diameter considerably larger than the connecting channel. The stomach terminated at the pyloric sphincter which consisted of a v/ell‐developed band of circular smooth‐muscle bundles effecting a division between the pyloric chamber and small intestine. The small intestine began with the duodenal ampulla, a dilated sac considerably smaller than the fundic chamber of the stomach. The rnucosa of this sac contained mucous glands throughout. The ampulla led without a separating sphincter into the duodenum proper which continued the intestine in a much more narrow tubular fashion. The mucosal lining of the duodenum was composed of villi and intestinal crypts. Although their occurrence varied among whales, enteroendocrine cells were identified within the mucous glands of the cardiac region, connecting channel, pyloric chamber, and cranial duodenum. The hepatopancreatic duct entered the wall of the duodenum shortly after the termination of the duodenal ampulla and continued intramurally along the intestine before finally joining the duodenal lumen.