bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathogenesis of osteopetrosis in the ia rat: Reduced bone resorption due to reduced osteoclast function
Authors: Marks Sandy C.
Published: February 2005

Osteopetrosis, a skeletal condition characterized by excessive accumulation of bone, is an inherited disease in man, rats and mice. In ia rats the condition undergoes spontaneous permanent remission beginning 30 to 50 days after birth, in contrast to the disease in mice and men. Thus, the ia rat offers a unique opportunity to analyze factors suspected of causing the skeletal condition.

In the present investigation bone formation and bone resorption have been measured at various ages in ia rats and normal littermates. Bone matrix formation, measured by 3H‐proline uptake, was decreased slightly during the first three postnatal weeks and elevated slightly thereafter. Bone resorption, stimulated by injection of parathyroid extract, was determined in vivo as the rate of release of 3H from bone after incorporation of 3H‐proline. Bone resorption was reduced 20% at two weeks and elevated 20% by three weeks. Administration of parathyroid extract or thyroxine, or a deficiency of thyrocalcitonin produced by thyroidectomy (supplemented with thyroxine), did not hasten remission. An abnormally high cytoplasmic concentration of acid phosphatase activity was observed in ia osteoclasts during the first two weeks. The skeletal signs of spontaneous remission, appearing between 30 and 50 days after birth, were preceded by a normal response of the serum calcium to exogenous parathyroid extract, by increased bone resorption and by a more normal cytoplasmic distribution of acid phosphatase activity during the third postnatal week.

These observations are interpreted to indicate that the osteopetrotic condition of ia rats is not due to deficiencies of parathyroid hormone or thyroxine or an excess of thyrocalcitonin but results from failure of osteoclasts to respond to stimuli promoting resorption. Specifically, these cells seem able to synthesize but not release normal amounts of the lysosomal enzyme acid phosphatase.
Effects of mammalian corticotrophin on the ultrastructure of presumptive interrenal cells in the opisthonephros of the lamprey, Petromyzon marinus L.
Authors: Youson John H.
Published: February 2005

The administration of mammalian corticotrophin to larvae and adult sea lamprey, Petromyzon marinus L., results in changes in fine structure of cells within presumptive interrenal tissue located in the opisthonephric kidneys. Compared to controls, stimulated cells show increases in the volume of smooth endoplasmic reticulum, mitochondria, and the Golgi apparatus with an accompanying decrease in numbers of lipid droplets. In addition, the plasma membrane near a perivascular space is commonly highly folded. Mitochondria are often of unusual configuration and possess “puffs” and the cristae are more tubular than in controls. The enlarged Golgi apparatus is accompanied by large numbers of coated vesicles.

The morphological features of corticotrophin‐stimulated presumptive interrenal cells of lampreys closely resemble the appearance of adrenocortical cells of mammals and the interrenal cells of other vertebrates after similar stimulation. These results suggest that these cells in lampreys and adrenocortical cells are likely homologs.
The atrioventricular valves of the guinea‐pig. I. A light microscopic study
Authors: Ellison Jeffrey P. , Hibbs Richard G.
Published: February 2005

The atrioventricular valves contain dense plexuses of adrenergic nerve fibers, derived from atrial and ventricular sources. Most of the adrenergic terminals are located in the lower third of the cusps. This region, which contains adrenergic terminals and acetylcholinesterase‐positive nerve endings is devoid of muscle fibers and blood vessels. The acetylcholinesterase‐positive endings may be sensory; and norepinephrine released from the adrenergic terminals may influence their performance. In the mitral valve, the atrial adrenergic plexus is separated from the ventricular plexus by a narrow zone that is free of adrenergic nerves. In most other respects the innervation, musculature and vascular supply of the mitral valve is similar to that of the tricuspid valve.

Each valve has an intrinsic skeleton. This is made up of collagenous “ribs” that pass up from the chordae tendineae and fan out in the cusps. “Ribs” from adjacent chordae overlap and interweave, forming a complex support system.

The musculature of the valves is complex and seems to have several functions. The annular muscle around the valve orifice may act as an atrioventricular sphincter, while offshoots that insert into the collagenous “ribs” of the cusp may assist the papillary muscles in maintaining tension on the cusps. The meshwork of muscle fibers between “ribs” may prevent ballooning of the cusps during systole. We found no consistent association between valvar muscles and nerves. Blood vessels are restricted mainly to the upper muscular part of the cusps, although a few capillary loops descend into the midzone of the cusps.
Electron microscopic studies of human pituitary tumors. I. chromophobic adenomas
Authors: Schechter Joel
Published: February 2005

Ten cases of chromophobic adenoma have been studied by electron microscopy; seven were associated with hypopituitarism and three with acromegaly. Comparison of the tumors revealed that morphological variations in parenchymal cell types were slight, and, based on characteristics of the secretory granules, a single cell type was predominant and common to both varieties of the tumor. The predominant cell type contained varying amounts of secretory granules that measured 80–200 mμ or more in diameter, and had an electronopaque core and perigranular halo. Though the features of these secretory granules were most like those in “normal” adult basophils this classification is considered doubtful. The core material of the secretory granules was homogeneously electron‐opaque in some granules and particulate in others. In addition to electron‐opaque core material many secretory granules contained aggregates of clear vesicles. Some granules did not contain clear vesicles but were closely associated with numerous cytoplasmic vesicles. Lysosomes were abundant and a consistent feature of the tumor cells. The present observations indicate that cell features are significantly altered in the cells of both varieties of chromophobic adenoma so that ultrastructural criteria used to identify cell types in “normal” pituitary glands are not applicable to the tumor cells.

Chromophobic adenomas associated with acromegaly varied more with respect to the features of the predominant cell type than did chromophobic adenomas associated with hypopituitarism. Cell features varied between cells with electronlucent cytoplasmic matrix and scant development of organelles to others with more electron‐opaque cytoplasmic matrix and more complex development of organelles. Common to both varieties of tumor were marked variations in the number and structure of mitochondria from cell to cell; occasionally mitochondria filled the cytoplasm.
Ultrastructural diversity in secretory granules of human major salivary glands
Authors: Riva Alessandro , Motta Giovanni , Riva‐Testa Francesca
Published: February 2005

Acinar cells of human major salivary glands, fixed and processed for electron microscopy under identical conditions, exhibit secretory granules endowed with distinctive ultrastructural features.
Three‐dimensional structure of the osmium‐impregnated golgi apparatus as seen in the high voltage electron microscope
Authors: Rambourg A. , Clermont Y. , Marraud A.
Published: February 2005

Osmication in an unbuffered aqueous solution of osmium tetroxide allows the forming face of the Golgi apparatus to be labeled in many cell types. This property was utilized to study the spatial configuration of this organelle by examining stereopairs of the same field taken at 1,000 KV after tilting a thick (1 to 7 μUm) section of − 7° or + 7° from the original (0°) position. When examined in 1 μm thick sections at magnifications ranging from 13,000 to 18,000 times, the osmic acid‐impregnated element of the Golgi apparatus of ganglion nerve cells, Leydig cells or Sertoli cells takes the appearance of a single layered polygonal network of tubules. This network can only be seen at electron microscope magnifications and is referred to as the primary network or structure of the forming face of the Golgi apparatus. When 2 to 7 μm thick sections are examined under progressively lower magnifications, the details of the primary structure remain discernible but become less conspicuous. The osmiophilic portion of the Golgi apparatus now extends over large areas of the cytoplasm to form an extensive continuous structure. This structure which is in the range of visibility of the light microscope is referred to as the secondary network or structure of the forming face. In ganglion nerve cells, the secondary structure consists of a perinuclear network showing slender projections reaching the nucleus and wider expansions approaching the cell surface; in the Leydig cells it appears as an ovoid structure located at one pole of the nucleus whereas in Sertoli cells it forms a cylindrical structure located in the main shaft of the cytoplasm and extending from the nucleus towards the lumen of the seminiferous tubule. Thus the forming face of the Golgi apparatus displays a primary structure; the tubular roughly polygonal network, which is similar in the three cell types and a secondary structure which varies from cell to cell.
The role of the convoluted segment of the proximal tubule in the disposal of 131I‐insulin in the rat kidney
Authors: Sottiurai Vikrom
Published: February 2005

It is generally accepted that in the kidney insulin is metabolized in the proximal tubule, but whether in the convoluted segment, the straight segment, or both has not been established. By means of autoradiography counting of radioactivity, and interrupted flow techniques, the following observations have been made. 131I‐labelled porcine insulin is metabolized exclusively in the convoluted segment of the proximal tubule. Although the glomerular filtrate is the major source of insulin supply to the renal epithelia, the peritubular capillary plexuses provide as much as 30% or more of the total insulin delivered to the renal epithelia. The epithelium of the convoluted segment is capable of sequestering 131I‐insulin from the peritubular capillary plexuses, a phenomenon which has not been established previously.
Bronchiolar neuro‐epithelial bodies in the neonatal mouse lungs
Authors: Hung Kuen‐Shan , Loosli Clayton G.
Published: February 2005

Bronchiolar neuro‐epithelial bodies in neonatal mice were studied by light and electron microscopy. These bodies occurred in thickened areas of the epithelium, and consisted of groups of specialized, non‐ciliated columnar epithelial cells with many cytoplasmic granules. These cells were usually closely parallel to one another and had elongated nuclei containing conspicuous peripheral chromatin condensations. These cells were associated with intra‐epithelial axons.

With electron microscopy, the non‐myelinated axon under the neuro‐epithelial body was observed to penetrate the basal lamina and enter the epithelial layer. After penetration, the intra‐epithelial axon containing numerous mitochondria lost its Schwann cell sheath, became enlarged, and ramified among the epithelial cells.

These innervated neuro‐epithelial bodies probably function as sensory receptors in the bronchioles.
A cytoplasmic inclusion in mouse trigeminal neurons
Authors: Peach Roy , Koch William E.
Published: February 2005

Mouse trigeminal neurons contained a cytoplasmic inclusion consisting of a dense particle (diameter ∼ 100 nm.) surrounded by a smooth surfaced membrane sometimes in continuity with the rough surfaced endoplasmic reticulum. The identity of the inclusion is uncertain but it may be related to intracisternal A type particles.
Altered fine structure of B lymphocytes correlated with defective terminal differentiation
Authors: Bockman Dale E. , Wu L. Y. Frank , Lawton Alexander R. , Cooper Max D.
Published: February 2005

Peripheral blood lymphocytes from three patients with defective differentiation of B cells were studied by routine electron microscopic techniques. One patient had severe combined immunodeficiency with rudimentary development of the B cell line. Two had immune deficits secondary to the B cell malignancy, chronic lymphocytic leukemia. Accumulations of tuboreticular structures were found in the cytoplasm of lymphocytes from the severe combined immune deficiency patient, sometimes in close association with annulate lamellae. The tuboreticular structures resemble those described in lymphocytes and endothelial cells of patients with systemic lupus erythematosus. In one patient with chronic lymphocytic leukemia, cylindrical arrangements of ribosomal material occupied the cytoplasm of many lymphocytes. These cylinders were observed in samples of blood drawn at different times and after tissue culture of lymphocytes with and without pokeweed mitogen. The other patient with chronic lymphocytic leukemia had circulating lymphocytes with material identified as IgM in the perinuclear spaces and dilated cisternae of the rough endoplasmic reticulum. This material sometimes had a crystalline structure.

These observations indicate that in some cases functional immunological deficits in B cells, manifested by failure to differentiate to mature secretory cells, may be correlated with morphological aberrations of protein‐manufacturing organelles within the cell.
Factors affecting the conversion of cross‐reinnervated skeletal muscles
Authors: Riley Dan A.
Published: February 2005

Greatly enhanced conversion of cross‐reinnervated muscles was obtained when the preexisting muscle fibers were injured causing dedifferentiation and redifferentiation in the presence of a “foreign” nerve.
Secretory processes in follicular cells of the bat thyroid. III. The occurrence of extracellular vesicles and colloid droplets during arousal from hibernation
Authors: Nunez Eladio A. , Wallis Jeffrey , Gershon Michael D.
Published: February 2005

Ultrastructural changes that occur in follicular cells of the bat thyroid gland just prior to, and immediately after arousal from hibernation are discussed in relation to the known changes which occur in thyroid function during arousal from hibernation. The most distinctive ultrastructural change that takes place just before emergence from hibernation is the occurrence, extracellularly, of concentrations of small vesicles lying in the colloid near the cell's apical plasma membrane. Similar accumulations of vesicles are absent in the apical cytoplasm of the follicular cell. Other principal changes from the early hibernating state found at this time are an increase in the number of apical vacuoles, dense granules and multivesicular bodies. These changes are followed at arousal itself by the appearance of large numbers of intracytoplasmic colloid droplets, often intimately associated with dense granules. An unusual feature of these follicular cells is that although they are rich in colloid droplets, apical pseudopods cannot be found.
Purkinje fibers of sheep papillary muscle: Occurrence of discontinuous fibers
Authors: Hondeghem L. M. , Stroobandt R.
Published: February 2005

Mapping of the peripheral specialized conducting system of the heart could contribute to an understanding of normal and abnormal impulse propagation. In this study, a sheep right anterior papillary muscle was sectioned serially and stained for Purkinje fibers with the periodic acid Schiff and hematoxylin procedure. The subendocardial Purkinje fibers entered the papillary muscle through its base and extended nearly to its apex. Except for one “mixed” fiber group, the subendocardial fibers did not connect to the deep Purkinje fibers, and both groups contained discontinuous Purkinje fibers. The fibers of the moderator band radiated in such a complex fashion that they could not be reconstructed exactly, but they generally disappeared in the ventricular wall through the base of the papillary muscle and false tendons. No direct connections between the subendocardial Purkinje fibers and those of the moderator band could be found within the boundaries of the papillary muscle, and this may form the basis for the relatively late activation of the papillary muscle as compared to the surrounding myocardial wall. The discontinuous fibers we observed are compatible with a current concept regarding the embryology of the ventricular specialized conducting system, and are not in conflict with normal impulse propagation.
Ethionine induced degeneration and regeneration in the rat parotid gland: An electron microscope study
Authors: Leeb Irwin Joel
Published: February 2005

The object of the present study was to establish a model for the study of parotid gland regeneration. Adult female Sprague‐Dawley rats were placed for 11 days on a protein‐free diet with daily intraperitoneal doses of aqueous DL‐ethionine equivalent to 0.5 mg/gm body weight, and returned to a normal diet on day 12. At varying intervals, both during and after intoxication, animals were sacrificed and the parotid glands prepared for study with the transmission electron microscope.

Ultrastructural observations indicated that damage was essentially limited to the acinar cells, in which the protein synthetic apparatus was the focus of injury. The rough endoplasmic reticulum displayed atypical configurations, loss of attached ribosomes and membrane fragmentation. In the Golgi region, an atypical structure, a “crystalloid” arose during intoxication. Because of the morphology and apparent formation of the “crystalloid” it was assumed to be an abnormal secretion product. Resumption of a normal diet resulted in the rapid restitution of the normal cytoarchitecture. During the first week of recovery, there was prominent mitotic activity in mature acinar cells.

It was concluded that the primary effect of ethionine upon the parotid gland is interference with the function of the protein‐synthetic apparatus, leading to morphologic alteration of the acinar cells. The mitotic activity observed during recovery indicated that in the adult rat, acinar cells retain the potential for proliferation.
An unusual membrane‐bound body in rat periosteal cells
Authors: Taylor John J. , Yeager Vernon L.
Published: February 2005

Cytoplasmic inclusions have been found in both normal and stimulated rat periosteal cells. These inclusions are bounded by a pentilaminar membrane similar to a tight junction and contain a core of granular material. The origin and function of this inclusion are unknown.
Ultrastructural studies of traumatic cataractogenesis: Observations of a repair process in mouse lens
Authors: Rafferty Nancy S. , Goossens William
Published: February 2005

Lenses of CFl mice were studied with the transmission electron microscope at frequent intervals through 13 months following a transcorneal needle injury to the lens. While this kind of injury causes a high incidence of traumatic cataract in the human and frog, it elicits a repair process in the mouse lens whereby the damaged capsule, epithelium and lens fibers are rapidly renewed and permanent lens opacity seldom occurs. Ultrastructural changes in lens epithelial cells adjacent to the wound, which precede and accompany localized cellular proliferation and production of new capsule, involve a rapid increase or enlargement of organelles associated with protein synthesis and assembly. The capsule and epithelium are repaired within a couple of months. Cortical lens fibers in the wound area undergo conformational changes into smaller, ordered arrays of “membranous sacs.” These are replaced within a week by normal appearing lens fibers. There is minimal degeneration or hyperplasia noted, and except for a few fibroblastic cells on the lens surface, little evidence remains of the injury by two months. Ultrastructural differences between mouse and human lens, such as presence or absence of dense bundles of microfilaments and desmosomes are considered in relation to lens shape and tension, and susceptibility to injury‐induced cataract.
Histological and three dimensional organization of the odontogenic organ in the lower incisor of 100 gram rats
Authors: Smith C. E. , Warshawsky H.
Published: February 2005

A three dimensional reconstruction of the epithelial tissue at the apical end of the lower rat incisor was made from serial 1 μm thick cross sections. This tissue formed an elongated structure, called the odontogenic organ, which was composed of a bulbous and a “U”‐shaped part. Both parts were joined to one another at the posterior aspect of the apical foramen. The bulbous part of the odontogenic organ was situated at the lingual side of the “U”‐shaped part and protruded anteriorly over the pulp. It was formed by cells of the outer dental epithelium and stellate reticulum whose organization suggested that the bulbous part was important in the production of cells for renewal of all the epithelia of the incisor. The “U”‐shaped part of the odontogenic organ was apparently derived from the bulbous part and delineated the pulp by forming the lateral, mesial and labial sidewalls around the apical foramen. It was composed of all the epithelial cell types recognizable as precursors to (a) cells of the enamel organ which form the enamel, and (b) Hertwig's epithelial root sheath, a part of the odontogenic organ which induces the formation of dentin on the lingual aspect of the incisor.
Histological and three dimensional organization of odontogenic organ in the upper incisor of 100 gm rats: Comparison with the lower incisor
Authors: Smith C. E.
Published: February 2005

The epithelial tissue forming the posterior aspect of the apical foramen in the upper incisor of the rat was reconstructed from 1 μm thick serial cross sections. Like the lower incisor, this portion of the odontogenic organ in the upper incisor was composed of a bulbous and a “U”‐shaped part. However, the bulbous part was considerably blunter and the “U”‐shaped part much larger in circumference in comparison to the lower incisor. Although no differences were found between the upper and lower incisor regarding the contents and the basic organization of cells within each part of the odontogenic organ, specific differences were found within the bulbous part in the upper incisor. There was a more definitive boundary between the outer dental epithelium and stellate reticulum, a more intimate relationship of cell streams to the stellate reticulum, and a noticeable lack of swirling of cells as part of the streams. These features suggest that the activity inside the bulbous part is less intense in the upper incisor than it is in the lower incisor. In addition, the relationships between the bulbous part, the “U”‐shaped part and the root sheath part of the odontogenic organ and the enamel organ were described for the upper incisor.
Fetal monkey absorption of 55Fe from amniotic fluid
Authors: Orlic Donald , Lev Robert
Published: February 2005

A single dose of 0.5 mCi radioiron (55Fe) was injected directly into the amniotic cavity of each of four pregnant monkeys near term. At 6 or 24 hours after 55Fe administration, samples of fetal jejunum, ileum, blood, spleen, liver, lung and fetal membranes were taken for radioautography and scintillation counts. Counts were also made on corresponding maternal tissues.

Intestinal radioiron levels and localization indicated that fetuses swallowed and absorbed 55Fe within 6 to 24 hours after injection. Silver grains over the meconium bodies of fetal ileum suggested that intestinal epithelium retained at least some of the absorbed radioiron. However, elevated 55Fe levels in fetal blood and hematopoietic organs indicated that transport of radioiron to the circulation had occurred, presumably through fetal intestine, extraembryonic membranes and/or fetal lungs. Transfer of 55Fe across the placenta from fetus to mother occurred at a slow rate, i.e., samples of maternal organs obtained at 24 hours gave low counts.
Scanning electron microscopy of yolk absorption in early chick embryos
Authors: Litke Larry L. , Low Frank N.
Published: February 2005

Fresh pullet eggs (White Leghorn Strain) were incubated from 6–19 hours. Blastoderms were fixed in situ with aldehyde fixative, post‐osmicated in 2% OsO4, dehydrated in acetone, criticalpoint‐dried, mounted ventral side up, coated with palladium‐gold wire and observed in a Cambridge Stereoscan S4 scanning electron microscope.

Large extracellular yolk granules had a smooth surface and appeared to break up into smaller particles. Similar particles have been observed intracellularly in transmission electron microscopy. Numerous microappendages, mostly ruffles, suggest phagocytosis as a method of absorption of yolk granules into the cells. Absorption of yolk by the cells of the blastoderm involves an initial break up of yolk granules followed by phagocytosis.
Morphological effects of a large single dose of cycloheximide on the intestinal epithelium of the rat
Authors: Altmann Gabriel G.
Published: February 2005

Adult male rats received 15 mg/kg cycloheximide and the subsequent morphological effects at three and six hours after injection were evaluated using histometry, light and electron microscopy, histological demonstration of terminal web and acid phosphatase, and radioautography with tritiated thymidine.

Rapid atrophy of the villi took place, progressing from the villus tip by premature exfoliation of epithelial cells. The crypts also diminished by random exfoliation of many crypt cells and by partial or complete disintegration. Mitosis and epithelial cell migration were absent. By six hours, the area occupied by the villi and the crypts per unit length of histological section was decreased by about 70–90% in most of the small intestine but only by about 40–60% in the duodenum and the terminal ileum. In the upper half of the villi, the epithelium was strongly positive for acid phosphatase and contained large numbers of round bodies resembling primary lysosomes. In the lower half, the microvillous border and terminal web were found to be disrupted. Animals receiving only 5 mg/kg cycloheximide also showed the atrophy of villi and crypts, and the round bodies resembling lysosomes.

Evidence from several sources has indicated that protein synthesis in normal villus epithelial cells subsides toward the villus tip and becomes minimal at exfoliation. At exfoliation, proteins responsible for epithelial cohesion probably fail because they are no longer replenished. Cycloheximide appears to accelerate this process.
A scanning electron microscopic study of the luteo‐follicular complex. II. Events leading to ovulation
Authors: Motta Pietro , Van Blerkom Jonathan
Published: February 2005

Morphological changes on the ovarian surface of different mammals both before and during ovulation have been examined by scanning electron microscopy. Preovulatory follicles were blisterlike structures that protruded markedly from the ovarian surface. Basal areas of preovulatory follicles were covered with polyhedral cells containing numerous microvilli, whereas on the lateral surfaces, superficial cells were elongated and possessed few microvilli. At the apex of the follicle, cells were very flattened and possessed few microvilli, which were present only in regions of intercellular contact. In some apical areas, cells appeared to be degenerating, whereas in other regions, groups of cells had “sloughed off.” In addition, a fluidlike material was observed to exude from intercellular spaces of the superficial epithelium and to cover some apical cells. By transmission electron microscopy, the same fluidlike material was observed to (1) infiltrate the connective tissue of the tunica albuginea, (2) accumulate under the basal lamina, and (3) distend intercellular spaces of the superficial epithelium.

Just prior to ovulation, large, irregular areas of the apex were ruptured and the oocyte, covered with a large amount of fluid, appeared to emerge from the follicle. At ovulation, the oocyte was not completely covered with follicle cells and the zona pellucida was clearly evident. The surface of the zona was quite irregular and contained numerous infoldings, channels and crypts. Follicle cells had polyhedral or star shapes and possessed large cytoplasmic evaginations that obliquely penetrated the zona. Both the zona pellucida and corona cells were covered with a fine layer of granular material.

The SEM results and parallel TEM observations suggest that a local increase of fluids (edema) may be an important factor in the final decomposition of the distended and weakened apex of the preovulatory follicle. In addition, the participation of follicle cells, smooth muscle cells and the oviduct in the escape of the oocyte from the ruptured follicle is discussed.
Histophysiological evidence for the secretion of polypeptides by the pineal gland
Authors: Lukaszyk Andrew , Reiter Russel J.
Published: February 2005

Histophysiological examinations of the bovine and monkey pineal gland indicate that this organ may be involved in the secretion of polypeptides. Using various histochemical procedures designed to identify peptidesecreting cells, granules and/or droplets of presumptive secretory product were identified within cellular processes, within the walls of blood vessels and associated with multilayered corpuscles (corpora arenacea). In bovine pineal tissue, the stained material was found most often in what appeared to be pinealocyte processes, as perivascular granules and associated with multilayered corpuscles. In the monkey pineal the stainable material was more distinct; this was probably due to the earlier fixation of the glands after death of the animals. In this species, the presumptive secretory material was found in nerve fibers, occasionally in glial cell and pinealocyte processes and within and around the walls of capillaries. In nerve fibers, the stained material sometimes resembled Herring bodies of the posterior pituitary gland. Similar material appeared to be located in capillary endothelial cells and within multilayered corpuscles. In pineal tissue of both species, calcium was detectable histochemically within multilayered corpuscles. Although tinctorially different, the presumptive neurosecretory material was similar to that found in the posterior pituitary gland. As a working hypothesis, we propose that polypeptides may be released from cells in conjunction with a carrier protein and that the mechanism of secretion of the polypeptide into the vascular system may involve its exchange for calcium. The calcium is then theoretically deposited in the multilayered corpuscles.
Carbohydrate histochemistry of the opossum submandibular and major sublingual glands
Authors: Pinkstaff Carlin A.
Published: February 2005

Submandibular and major sublingual salivary glands of the opossum contain histochemically demonstrable neutral mucosubstances, nonsulfated acid mucosubstances and sulfomucins. Sialomucins could not be demonstrated conclusively with the methods used in this study. Special serous cells of the opossum submandibular gland contained low concentrations of acidic mucosubstances but no appreciable concentration of neutral mucosubstances was seen. Sulfomucins were not observed in special serous cells. The mucous tubules of the submandibular gland contained high concentrations of neutral mucosubstances. No appreciable acidic mucosubstance was demonstrated in the submandibular gland mucous tubules. Unlike the mucous tubules of the submandibular gland, the major sublingual gland mucous tubules contained high concentrations of both neutral and acidic mucosubstances. The mucous tubules often contained sulfomucin‐positive cells interspersed among cells that contained high concentrations of non‐sulfated acidic mucosubstance. Marked staining of sulfated acidic mucosubstance was seen only in the major sublingual gland, in both the mucous tubules and in the seromucous demilunes. The seromucous demilunes contained both sulfated and non‐sulfated acidic mucosubstances.
Fine structural observations on hemopoiesis in the chorioallantoic placenta of the marmoset
Authors: Jollie William P. , Haar Jack L. , Craig Shirley S.
Published: February 2005

Hemopoietic sinuses in the chorionic trabeculae of marmoset placenta were examined electron microscopically at several stages of pregnancy. Tissues were prepared both by standard technique and following injection of exogenous peroxidase into the maternal circulation prior to autopsy, and subsequent cytochemical localization of its reaction product in the fetal placenta. Aside from their dilated size and cellular content, the sinuses resembled the allantoic capillaries of the peripheral umbilical circulation in this species; and, in early and midgestational placentas, sinusal endothelium, like that of capillaries, looked mesenchymal. Within the sinusal lumina, differentiating elements in the erythroid line were present in placentas at all stages. Such cells appeared to arise both by a process of proliferation of undifferentiated progenitors from the sinusal lining and by mitosis of pre‐existing erythroid cells. Only the latter process was observed in the mature placenta near term. Granulopoiesis was not observed at any stage; on the other hand, cells in the thromboid line were identified in placentas believed to be near midgestation; and large intrasinusal phagocytes were present in both midgestational and late placentas. In the latter, they were seen to have endocytosed peroxidase, and, by tenuous, dendriform processes, to be related anatomically to large numbers of erythroid cells. Early in gestation, the developing erythroid elements were closely related by areas of contact, both to each other and to the delimiting endothelium of the sinuses.
Labelling of murine epidermal Langerhans cells with H3‐Thymidine
Authors: Mackenzie Ian C.
Published: February 2005

Epidermal Langerhans cells may be identified by light microscopy by their strongly positive reaction following incubation for ATPase activity. Intact sheets of epidermis from mice killed at various time intervals following a single pulse label of H3‐thymidine were incubated to demonstrate ATPase activity and subsequently processed for autoradiography. In specimens taken one hour after labelling, many basal keratinocytes were labelled but very few ATPase positive dendritic cells. At subsequent time periods a few pairs of labelled ATPase positive cells were found but individually labelled cells were not observed. The findings suggest that epidermal Langerhans cells from a very stable (labelling index < 0.01%) self‐replicating population which divides to maintain cell spacing during growth. No evidence was found for migration and interchange of Langerhans cells with the connective tissue, or for an origin of Langerhans cells by transformation of another cell type.
Mitochondrial granules of chondrocytes in cryosections of growth cartilage
Authors: Ali S. Yousuf , Wisby Angela
Published: February 2005

Fresh frozen specimens of growth cartilage have been drysectioned and examined in the electron microscope without any staining. Dense granules in the mitochondria of chondrocytes were observed near calcifying areas. This confirms the presence of these mineral granules in the original tissue because this technique avoids the preparative artefacts of conventional electron microscopy.
Mitotic cells and their microappendages in the primitive streak of the chick embryo
Authors: Harri James E. , Low Frank N.
Published: February 2005

Fresh pullet eggs (White Leghorn Strain) were incubated to the primitive streak stage of development. Blastoderms were fixed in situ with isotonic aldehyde fixatives and prepared for scanning electron miscroscopy by means of post‐osmication, critical point drying and gold‐palladium coating.

Cells judged to be in various stages of mitosis by their surface contours were numerous on the ventral surface of the chick blastoderm. Cells which were in the late preparatory stages for mitosis had rounded up from their surroundings. Microvilli dominated the surface. The degree of separation and number of microvilli increased until late metaphase or anaphase. Mitotic cells did not completely separate themselves from adjacent cells. Ruffles and blebs were not prominent during mitotis and long filopodia were absent. A definite localization of microappendages (microvilli, blebs, ruffles) to the area of cytokinesis was evident in early telophase and persisted through daughter cell formation.
The stimulatory effects of diethylstilbestrol and diethylstilbestrol diphosphate on the reticuloendothelial cells of the rat spleen
Authors: Steven William M. , Snook Theodore
Published: February 2005

The effects of the estrogenic compounds, diethylstilbestrol (DS) and diethylstilbestrol diphosphate (DSP) on morphologically demonstrable characteristics of reticuloendothelial (RE) cells were studied in rat spleen. These included metalophilia, acid phosphatase, nonspecific esterase and phagocytosis. Routine histological and histochemical techniques were used to determine the distribution of metalophilic cells, hydrolytic enzymes, the presence of intracytoplasmic PAS‐positive material, hemosiderin sequestration, and the ability to phagocytose injected carbon particles and bacterial organisms.

Changes in these parameters associated with increased RE function were observed in several regions of spleens of DS or DSP‐treated animals. The marginal metalophils at the periphery of the nodule, normally not phagocytic in animals of the age studied, became phagocytic and demonstrated increased metalophilic and enzymatic activity. The red pulp was characterized by increased densities of cells in pulp cords demonstrating metalophilia, hydrolytic enzyme activity, PAS positivity and hemosiderin. Phagocytosed material was limited to cells in the pulp cord. The reactions of the sinus‐lining cells were not affected by this treatment. Results indicated that the marginal metalophils have the capacity to become fully functional RE cells under the influence of these drugs.
Localization of antisera to LHβ and FSHβ in the rat pituitary gland
Authors: Herbert Damon C.
Published: February 2005

Pituitary glands from adult male and female rats were stained by the immunocytochemical bridge technique with antisera to ovine LHβ and human FSHβ. Peroxidase reaction product was localized in the same PAS‐positive cells with both antisera. The cells varied in size and topographical distribution within the pars distalis. These observations support the concept that a single cell type is responsible for the synthesis of both LH and FSH in the rat.
Junctions between sinusoidal endothelial cells in fetal rat liver
Authors: Montesano R.
Published: February 2005

During a freeze‐fracture study of tight junctions in fetal rat liver (Montesano et al., '75) unusual patterns of intramembranous particles were observed in regions of contact between sinusoidal endothelial cells. These patterns were mainly represented by arrays of particles, often associated with linear elevations or crests in the membrane A‐face; they may represent abortive forms of tight junctions.
Patterns of mitosis in hamster epidermis
Authors: Mackenzie I. C. , Zimmerman K. L. , Wheelock D. A.
Published: February 2005

Alignment of the flattened keratinizing cells of the upper strata of mammalian epidermis leads to the formation of columnar units of structure. In mouse epidermis, mitoses have been found to occur relatively infrequently in the region beneath the center of each cell column where a non‐keratinocyte dendritic cell, usually with features typical of an epidermal Langerhans cell, is situated. The observed pattern of mitosis could therefore be due either to displacement of central keratinocytes by Langerhans cells or indicate some control of keratinocyte proliferation related either to the Langerhans cells or to the overlying cell columns. No relationship exists between the position of Langerhans cells and epidermal cell columns in hamster epidermis but measurement of the position of mitosis has shown a reduced frequency of occurrence of mitosis beneath the central region. This pattern of mitosis is therefore unrelated to Langerhans cells and appears to reflect differences in the mitotic potential of basal keratinocytes which could be associated with feedback from the overlying cell columns or with an intrinsic pattern of basal cell activity.
Light, fluorescence and electron microscopic studies of rabbit subclavian glomera
Authors: Hansen John T. , Yates Robert D.
Published: February 2005

The subclavian glomera (aortic bodies) of young New Zealand white rabbits were studied with the light, fluorescence, and electron microscopes. Two cell types were identified: type I, granule‐containing (chief) cells, and type II, agranular (sustentacular) cells. The type I cells possessed large nuclei, the normal complement of cytoplasmic organelles and numerous electron‐opaque cytoplasmic granules. The type II cells were agranular with attenuated cytoplasmic processes which partially or completely ensheathed the type I cells. The glomera were well vascularized. Capillary endothelial cells contained numerous pinocytotic vesicles, but few fenestrae. Two profiles of nerve terminals were observed. One, apposing the type I cells, contained numerous electron‐lucent vesicles, several dense‐cored vesicles, mitochondria and possessed membrane specializations resembling those usually observed in synaptic zones. The other profile contained abundant mitochondria and a few electron‐lucent and densecored vesicles. Structural specializations were not observed on the apposed membranes of these terminals or adjacent to type II cells.

Fluorescence histochemistry revealed an intense yellow‐green fluorescence in the glomera, which indicated the presence of biogenic amines, possibly primary catecholamines or an indolamine. The electron‐opaque granules observed in the type I cells were believed to be the storage sites for these amines. The subclavian glomera were found to be morphologically similar to the carotid body which is a known chemoreceptor.
An electron microscopic study on the effects of reserpine on the subclavian glomera of the rabbit
Authors: Hansen John T. , Yates Robert D. , Chen I‐Li
Published: February 2005

Young male and female New Zealand white rabbits were given a daily subcutaneous injection of reserpine (Serpasil, Ciba; 3 mg/kg) for two days and were sacrificed 24 hours after the last injection. The subclavian glomera (aortic bodies) were processed for electron microscopy to determine the effects of this biogenic amine depleting agent on the electron‐opaque cytoplasmic granules of the parenchymal type I cells.

Observations of glutaraldehyde‐osmium tetroxide fixed glomera from reserpinized animals showed a slight decrease in granule density of the type I cells. Glomera fixed in glutaraldehyde and incubated in potassium dichromate (pH 4.1) demonstrated a reduction in granule opacity following reserpine treatment. Control glomera incubated in potassium dichromate displayed electron‐opaque granules. These results indicate that reserpine does deplete the amines without granule disappearance or changes in granule population. The positive reaction of the control tissue granules to potassium dichromate incubation suggests that the predominant biogenic amines in the electron‐opaque granules are unsubstituted monoamines. Persistence of the opaque granules following reserpinization and glutaraldehyde‐osmium tetroxide double fixation, may be due to aminebinding protein within the granules. The mode of granule depletion could not be ascertained with certainty.
Immunocytochemical localization of somatostatin in cell bodies of the rat hypothalamus
Authors: Elde Robert P. , Parsons Jonathan A.
Published: February 2005

Cell bodies of small to moderate‐sized neurons in the female rat hypothalamus were stained specifically for somatostatin (SRIF) by means of the unlabeled antibody‐peroxidase‐antiperoxidase immunocytochemical method. SRIF‐positive perikarya were scattered throughout the periventricular nucleus in a limited region extending from the middle of the optic chiasm to the rostral margin of the median eminence. The same neurons were revealed with either rabbit (R) or guinea pig (GP) anti‐SRIF antisera. Positive cell bodies were more readily assessed with GP antibodies because nonspecific background staining was much less with these than with R anti‐SRIF. Positive perikarya were not observed in other hypothalamic nuclei and ependymal elements were also immunocytochemically negative.
A minimum‐surface mechanism to account for the organization of cells into columns in the mammalian epidermis
Authors: Menton David N.
Published: February 2005

It has recently been discovered that the stratum corneum and superficial living epidermis of mammalian skin are organized into neat vertical columns of interdigitating cells. The mechanism for this organization has not yet been determined. This study shows that the stacked organization is not unique to the epidermis but also occurs in cork cambium and the pith of woody plant stems. The structural and spatial organization of the stacked cells in these tissues were compared and found to approximate closely the shape of Kelvin's minimum‐surface polygon, the tetrakaidecahedron. Paper models of flattened tetrakaidecahedra were constructed and found to stack in columns of interdigitating units which are consistent with all of the structural details seen in stacked cells observed under the light and the scanning electron microscopes. Indeed, only polygons of this type are capable of aggregating without interstices in the manner of the stacked cells. A study of stacked arrays of these models has revealed a mechanism by which the epidermis might become organized in columns of stacked and interdigitating cells. The proposed mechanism assumes that cells within an array seek the smallest possible surface‐to‐volume ratio and, under appropriate conditions, form stacked tetrakaidecahedra.
Platelets, endothelial cells and macrophages in the spleen. An ultrastructural study on perfusion‐fixed organs
Authors: Elgjo Ragna Følling
Published: February 2005

Rabbit spleens have been examined after perfusion fixation with and without prior washing with various fluids. The platelets were stored in the splenic sinuses and in the cord spaces as single platelets, or in loosley packed aggregates which appeared to be anchored to the endothelium by one or a few platelets. After washing prior to fixation most of the platelets disaggregated and regained their normal shape. Some platelets adhered to morphologically normal endothelium even after prolonged perfusion. Occasionally, platelets were observed inside splenic endothelial cells. Others were closely associated with macrophages, many of which also contained engulfed platelets.

There was no morphological evidence of a particular platelet population being retained in the spleen after washing.

In the sinuses special granule‐rich cytoplasmic structures were observed. They were interposed between ordinary endothelial cells and contained a large number of small lysosome‐like granules. Nuclei were never observed in these structures, probably because they consisted of pseudopod‐like protrusions. Their origin and function are discussed. They may represent actively phagocytizing elements.