bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in uterine mast cells during the estrous cycle in the Syrian hamster
Authors: Brandon Janet M. , Evans Janet E. 
Published: February 2005

AbstractAdult virgin female Syrian hamsters were killed at known stages of the estrous cycle, and mast cells were counted in the myometrium, endometrium, and mesometrial‐triangle region of the uterus and in the pinna. Tissues were fixed in Helly's solution, and mast cells were stained using 0.06% toluidine blue in 0.12 M Michaelis' veronal acetate‐hydrochloric acid buffer, pH 4.5. The number of mast cells in the myometrium and endometrium was found to vary with the estrous cycle, whereas the number in the mesometrial‐triangle region and the pinna showed no such variation. The number of mast cells in the myometrium and endometrium was lowest on day 4 of the cycle (the day before the night during which ovulation would occur) and increased approximately twofold to maximal levels found on days 1 and 2. Intermediate levels were seen on day 3. The origin of the increase in mast cell numbers from day 4 to day 1 was investigated using a combined alcian blue–safranin stain to differentiate between immature and mature mast‐cell granules. The results obtained did not support the hypothesis that the increase was due to de novo differentiation of mast cells from precursors, but, equally, no evidence was obtained to refute this hypothesis.
Bone formation by isolated calvarial osteoblasts in syngeneic and allogeneic transplants: Light microscopic observations
Authors: Moskalewski Stanislaw , Boonekamp Piet M. , Scherft Johannes P. 
Published: February 2005

AbstractTaking advantage of recently developed methods for osteoblast isolation, we used these cells to study bone morphogenesis in syngeneic and allogeneic intramuscular transplants.Syngeneic osteoblasts from fetal rat calvaria produced small islands of bone by the third day after transplantation. These islands increased in size and began to fuse after about 14 days. At the surface of the woven bone laid down first, lamellar bone developed. The amount of this bone increased, and in 56‐day‐old transplants solid blocks of bone were present. Osteoclasts were scarce, and the woven bone remained unresorbed. Bone marrow was absent. The structure of bone in transplants differed from that of mature calvarial bones in which only remnants of woven bone remained and bone marrow was well developed. The scarcity of osteoclasts in transplants could be caused by their relative paucity among the injected cells, since these cells responded strongly to added parathyroid hormone by increased production of cyclic adenosine monophosphate (cAMP) but only weakly to calcitonin.Osteoblasts isolated from the surface of calvarial lamellar bone of 28‐day‐old rats formed woven bone similar to the bone formed by fetal cells. This suggests that the type of bone produced does not depend on the intrinsic properties of the osteoblasts.Bone formed in an allogeneic system was surrounded by infiltrations containing lymphocytes, macrophages, and osteoclastlike cells in 14‐day‐old transplants. Osteoblasts at the bone periphery were destroyed and bone matrix was resorbed by infiltrating cells. Numerous bone lacunae were enlarged, suggesting the occurrence of osteocytic osteolysis.Isolated osteoblasts cultured for three population doublings or longer did not form bone after transplantation, although they retained some reactivity toward parathyroid hormone.
Structure, cytochemistry, endocytic activity, and immunoglobulin (Fc) receptors of rat testicular interstitial‐tissue macrophages
Authors: Miller Scott C. , Bowman Beth M. , Rowland Heidi G. 
Published: February 2005

AbstractMacrophages are common in rat testicular interstitial tissues. Interstitial‐tissue macrophages were characterized using ultrastructural, cytochemical, immunologic, and autoradiographic methods. Testicular interstitial‐tissue macrophages have a single indented nucleus, paranuclear Golgi complex, rough endoplasmic reticulum, coated vesicles, and numerous heterogeneous lysosomal vacuoles. Long filopodia and lamellopodia extend from the macrophage cell body into the lymphatic space. Macrophages are usually found adjacent to Leydig cells, and numerous Leydig cell processes are inserted into coated membrane invaginations on the macrophage surface. Secondary lysosomal vacuoles in the macrophage are cytochemically reactive for acid phosphatase (trimetaphosphatase) and aryl sulfatase. Testicular interstitial macrophages are endocytically active, avidly incorporating exogenously administered trypan blue dye and monomeric plutonium‐citrate. Macrophages were isolated from the testes by allowing them to adhere to glass. The isolated macrophages were found to have receptors for the Fc portion of immunoglobulin G on their surface. The association of macrophages with Leydig cells and their endocytic and immunologic activity suggests that these cells may play an important role(s) in testicular functions. In addition, the ability of these cells to incorporate exogenous materials indicates that they could have a role in gonadal toxicity reactions.
Difference in muscle spindle structure between pigeon muscles used in aerial and terrestrial locomotion
Authors: Maier Alfred 
Published: February 2005

AbstractMuscle spindle density (number of spindes per gram of muscle) of all 29 muscles of the forearm and leg of the domestic pigeon was evaluated by counting receptors in van Gieson‐stained serial cross sections. Extra‐ and intrafusal fiber‐type profiles were determined from histochemical preparations. Muscles of the leg had on the average significantly more avian slow‐twitch oxidative extrafusal fibers (22.5 vs. 0.8%) and slower contraction times than muscles of the forearm, but fiber‐type profiles and gross actions of muscles showed no consistent relation to the relative abundance of receptors. Differences in intrafusal fibertype composition among spindles were sought because of their potential effect on the quality of the afferent discharge. The number of intrafusal fibers per spindle was on the average significantly less (4.57 vs. 5.99) in the muscles of the leg than in those of the forearm; and of spindles with the same number of intrafusal fibers, those in the leg had smaller periaxial spaces. Distribution of intrafusal fiber types identified with the myofibrillar adenosine triphosphatase reaction differed among spindles of varying sizes. An acid‐ and alkali‐labile type occurred most frequently (P = 0.05) in spindles with one to three intrafusal fibers, and an acid‐labile and alkali‐stable type was most often seen (P = 0.05) in spindles with 4 to 7 intrafusal fibers. The smaller receptors were more abundant in the leg, while the larger ones were about equally distributed between the two extremities. Muscle fibers with dimensions that sometimes approached small extrafusal fibers were present in about 3% of the axial bundles examined, most of them in the forearm. The selective morphological variation of avian muscle spindles may represent the structural basis for qualitatively different afferent discharges that relate to the characteristic types of locomotion served by the two extremities.
Iron loading in the liver of parasitic adult lampreys, Petromyzon marinus L
Authors: Youson J. H. , Sargent P. A. , Sidon E. W. 
Published: February 2005

AbstractElectron microscopic and histochemical procedures were used to describe iron loading in the normal liver of parasitic adult sea lampreys, Petromyzon marinus L. Ferric iron is present in large quantities as ferritin in the cytoplasmic matrix, in hemosiderin granules, and in large vacuoles of hepatocytes. Ferritin is also found in the lateral intercellular space, in the perivascular space, and in the sinusoidal lumen. Large crystals in the cytoplasmic and nuclear matrices of some hepatocytes likely represent excessive aggregations of ferritin molecules. Ferrous iron is localized at the lateral cell membrane and vacuolar membranes of hepatocytes. Iron accumulation is less significant in Kupffer cells which are present in small numbers. The relationship of iron loading in the adult lamprey liver to the sanguivorous diet, the rate of erythrophagocytosis, the absence of bile ducts and canaliculi, and the nature of iron‐binding proteins in the plasma are considered. Emphasis is placed on the similarity of the above morphological findings to those resulting from experimentally induced and pathological states of iron loading in other vertebrates, and on the potential use of the lamprey as a model for studying iron loading in the vertebrate liver.
Morphometric analysis of the corpus luteum of 16‐day pregnant rats: The effect of preparative procedures on volume of luteal cell, interstitial, and vascular compartments
Authors: Dharmarajan A. M. , Meyer G. T. , Bruce N. W. 
Published: February 2005

AbstractThe volumes of the major tissue compartments, vascular space, interstitial space, and luteal cells, in the corpus luteum (CL) of 16‐day pregnant rats were determined morphometrically after different fixation procedures. Ovaries were fixed by perfusion at physiologic pressures (PF), by immersion directly in fixative (IF), by immersion after clamping blood vessels to prevent escape of blood (IFC), or by immersion after administration of heparin to prevent blood clotting (IFH). Three CL in each of eight ovaries were examined for each fixation method. Total volumes were significantly larger in CL fixed by PF and IFC, and approximated physiologic volumes as assessed from frozen ovaries. Perfusion‐fixed CL had significantly larger vascular and interstitial spaces and smaller cell volumes than immersion‐fixed CL. Capillary surface area varied significantly between the four groups in accordance with absolute volume of vascular space. Estimated numbers of endothelial cells and amounts of connective tissue differed significantly, presumably due to difficulties in identifying these components in immersion‐fixed CL with collapsed vessels. The fixation methods used caused substantial fluid shifts between the three major compartments. A theoretical approach for considering these shifts and the likely physiologic situation was developed.
“Synaptic” ribbons and spherules of the guinea pig pineal gland: Inverse day/night differences in number
Authors: Vollrath L. , Schultz R. L. , McMillan P. J. 
Published: February 2005

AbstractThe present study deals with the functionally enigmatic “synaptic” ribbons and spherules of guinea pig pinealocytes. Whereas the ribbons have been shown to exhibit a 24‐hr rhythmicity with low numbers during the day and high numbers at night, very little of a definitive nature is known about the spherules. Sixteen male guinea pigs of the Hartley strain were perfusion fixed, 8 between 0900–1100 hr, and 8 between 2100–2300 hr. The ribbons and spherules were counted in the pineal parenchyma of the proximal, intermediate, and distal regions. In confirmation of earlier studies, it was found that “synaptic” ribbons are equally abundant in the proximal, intermediate, and distal regions of the gland, during both the day and the night, and that they increase significantly in number at night when compared with daytime values. The spherules, by contrast, are more abundant proximally and are present in greater numbers during the day than at night. As ribbons and spherules are usually not found in one and the same pinealocytic profile, and based on previous electrophysiological studies, it is proposed that the ribbons are morphological markers of nocturnally active pinealocytes, whereas spherules characterize diurnally active pinealocytes.
Sertoli cells of the golden‐mantled ground squirrel (Spermophilus lateralis): A model system for the study of shape change
Authors: Vogl A. W. , Lin Y. C. , Dym M. , Fawcett D. W. 
Published: February 2005

AbstractSertoli cells of the ground squirrel (Spermophilus lateralis), a seasonal breeder, were examined by light and electron microscopy and their structure, particularly the organization of the cytoskeleton, was related to events that occur in the seminiferous epithelium during spermatogenesis. Among the events considered and described are the apical movement of elongate spermatids, withdrawal of residual cytoplasm from germ cells, transport of smooth endoplasmic reticulum (SER) between the base and apex of the Sertoli cells, and sperm release. These events are dramatically evident in this species because the seminiferous epithelium is thin, i.e., there are few germ cells, and both the germ cells and Sertoli cells are large.Sertoli cells of the ground squirrel have a remarkably well developed cytoskeleton. Microfilaments occur throughout the cell but are most evident in ectoplasmic specializations associated with junctions. Intermediate filaments occur around the nucleus, as a layer at the base of the cell, and adjacent to desmosome‐like junctions with germ cells. Intermediate filaments, together with microtubules, are also abundant in regions of the cell involved with the transport of SER, in cytoplasm associated with elongate spermatids, and in processes that extend into the residual cytoplasm of germ cells. Our observations of ultrastructure are consistent with the hypothesis that Sertoli cell microtubules are involved with the movement of germ cells within the seminiferous epithelium, and further implicate these structures as possibly playing a role in the retraction of residual cytoplasm from germ cells and the intracellular transport of SER. The abundance and organization of intermediate filaments suggest that these cytoskeletal elements may also be involved with events that occur during spermatogenesis.
Colchicine‐induced changes in the cytoskeleton of the golden‐mantled ground squirrel (Spermophilus lateralis) sertoli cells
Authors: Vogl A. W. , Linck R. W. , Dym M. 
Published: February 2005

AbstractStudy of Sertoli cells of the ground squirrel provides a unique opportunity to examine cell structure and function. The cells are large, have an elaborate cytoskeleton, and undergo dramatic changes in organization during spermatogenesis. Microtubules (MTs) are prominent elements of the cytoskelton and appear to be associated structurally with many of the events that occur during sperm production. To investigate the function of MTs, animals were injected subcutaneously with colchicine, and their seminiferous epithelia examined by light and electron microscopy. Some animals were injected with 30–80 mg of the drug per kg body weight and sacrificed 3 to 5 hr later. Others were given 0.3 mg/kg/day for 6 days and processed on day 7. Virtually no MTs were seen in Sertoli cells after short‐term treatments, and their numbers were greatly reduced after the long‐term injections. Intermediate filaments were very evident throughout the cytoplasm of treated cells, particularly in the short‐term studies. Moreover, a close association of some of these filaments with centrioles was observed. In all cases, elongate spermatids which normally move apically did not do so. Indeed, some spermatids appear to have been pulled to a basal position after having moved apically prior to treatment. Also, smooth endoplasmic reticulum (SER) accumulated basally in the Sertoli cell, unlike controls, and the acrosomes of late spermatids developed abnormally or did not complete their shape changes. Cell junctions appeared normal and sperm release was observed. In conclusion, our data suggest that Sertoli cell MTs are necessary for the normal development and translocation of spermatids in the seminiferous epithelium and are involved with positional changes in Sertoli cell SER. They do not appear essential for the maintenance of cell junctions.
Immunocytochemical localization of glucagonlike and gastric inhibitory polypeptidelike peptides in the pancreatic islets and gastrointestinal tract
Authors: Smith Phillip H. 
Published: February 2005

AbstractThe distribution of cells displaying glucagonlike or gastric inhibitory polypeptide (GIP)‐like immunoreactivity was examined in the pancreatic islets and gastrointestinal tracts of rats, dogs, and humans. A‐cells in the pancreatic islets in all three species were stained by antisera having regional specificity for pancreatic‐type glucagon, gut‐type glucagon (glicentin), or GIP. Oxyntic A‐cells of the gastric mucosa in dogs and humans also were stained comparably by these three antisera. In contrast, the K‐ and L‐cells in the intestinal mucosa of those species were stained only by antisera capable of reacting with GIP or gut‐type glucagon, respectively. Tests of antibody specificity showed that the GIP antiserum did not cross‐react with either pancreaticor gut‐type glucagon. Likewise, the glucagon antisera showed no cross‐reactivity with GIP. Hence, these findings suggest that pancreatic and gastric A‐cells contain a peptide with GIP‐like immunoreactivity distinct from glucagon or glicentin per se. Although the exact basis of the GIP‐like immunostaining of A‐cells is unknown, it may be due to the presence of a glucagon precursor sharing certain amino‐acid sequences with GIP. This hypothesis is consistent with several recent investigations showing that the processing of proglucagon molecules differs between the A‐ and L‐cells.
Surface architecture of the mucosal epithelium of the cat trachea: II. Structure and dynamics of the membranous portion
Authors: Tandler Bernard , Sherman James M. , Boat Thomas F. , Wood Robert E. 
Published: February 2005

AbstractBronchoscopic examination of anesthetized cats revealed that the trachea is capable of considerable change in caliber via lateral expansion of the membranous trachea. The morphological basis for this expansile capacity was determined by correlated light microscopy and scanning and transmission electron microscopy. The organization of the membranous trachea differs from that of the cartilaginous trachea. The mucosa is arranged in a series of longitudinal folds that open like an accordion when stretched laterally. These fold are not random, but appear to depend on rows of nonciliated, microvillusrich cells that form flexure lines in the surface epithelium. The mitochondria in such cell have a condensed configuration, indicating a high level of oxidative metabolism and suggesting that they may participate in transport processes that modify the luminal contents. Goblet cells, which are relatively sparse in the membranous trachea, have mitochondria in which the prominence of matrix granules and degree of mucus storage are inversely related. Mitochondrial morphology allows goblet cells that have discharged their mucin content to be readily distinguished from the microvillus‐rich cells, even when their luminal surfaces lie outside the thickness of a section.
Is there a medial nucleus of the trapezoid body in humans?
Authors: Richter Ernst A. , Norris Barbara E. , Fullerton Barbara C. , Levine Robert A. , Kiang Nelson Y. S. 
Published: February 2005

AbstractThe medial nucleus of the trapezoid body (MNTB) appears to be a prominent auditory structure in many mammals. However, the presence of an MNTB in the human brain has not been clearly established. One of the most characteristic features of the cat MNTB is the presence of large somatic endings with multiple synaptic sites, the calyces of Held. We examined adult human brains at both light and electron microscopic levels and found neurons with unusually large endings in a location that is similar to that for the MNTB in other animals. Moreover, the sizes and shapes of some cells in this area are similar to the principal cells of the cat MNTB. These observations support the idea that humans have cells that resemble MNTB neurons in other species. It has been suggested that the cat MNTB may be involved in the generation of wave 3 of its brainstem auditory evoked potentials, so the presence of an MNTB in the human brain may have implications in interpreting brainstem potentials in man.
Cytochemical analysis of alkaline phosphatase and esterase activities and of lectin‐binding and anionic sites in rat and mouse Peyer's patch M cells
Authors: Owen R. L. , Bhalla D. K. 
Published: February 2005

AbstractM cells in Peyer's patch follicle epithelium endocytose and transport luminal materials to intraepithelial lymphocytes. We examined (1) enzymatic characteristics of the epithelium covering mouse and rat Peyer's patches by using cytochemical techniques, (2) distribution of lectin‐binding sites by peroxidase‐labeled lectins, and (3) anionic site distribution by using cationized ferritin to develop a profile of M cell surface properties. Alkaline phosphatase activity resulted in deposits of dense reaction product over follicle surfaces but was markedly reduced over M cells, unlike esterase which formed equivalent or greater product over M cells. Concanavalin A, ricinus communis agglutinin, wheat germ agglutinin and peanut agglutinin reacted equally with M cells and with surrounding enterocytes over follicle surfaces. Cationized ferritin distributed in a random fashion along microvillus membranes of both M cells and enterocytes, indicating equivalent anionic site distribution. Staining for alkaline phosphatase activity provides a new approach for distinguishing M cells from enterocytes at the light microscopic level. Identical binding of lectins indicates that M cells and enterocytes share common glycoconjugates even though molecular groupings may differ. Lectin binding and anionic charge similarities of M cells and enterocytes may facilitate antigen sampling by M cells of particles and compounds that adhere to intestinal surfaces in non‐Peyer's patch areas.
The sertoli cell junctional complex: Structure and permeability to filipin in the neonatal and adult guinea pig
Authors: Pelletier R. ‐Marc , Friend Daniel S. 
Published: February 2005

AbstractThe development and maintenance of the Sertoli cell junctional complex were investigated in prepubertal and adult guinea pigs. To correlate the structure of the blood‐testis barrier with its permeability, the polyene antibiotic filipin (a cholesterol‐binding agent of low molecular weight: 570.70) was added to the fixative as a tracer visible in freeze‐fracture replicas. Discontinuous zonules, intermediate junctions (i.e., adhering fasciae) and gap junctions all proved permeable to filipin in the two age groups. Only the continuous occluding zonules characteristic of the adult guinea pig's testis were impermeable to the tracer.In pubertal animals, the establishment of the blood‐testis barrier coincided with the completion of the junctional strands in occluding zonules. The formation of occluding zonules was similar in the newborn and the adult. In the adult, the Sertoli cell junctional complexes contained three types of cell junctions: occluding, adhering, and gap junctions. The sequence of occluding and adhering junctions from the base to the apex of the epithelium was the reverse of that demonstrated in most epithelia. The impermeable continuous occluding zonules at the base showed parallel patterns of uninterrupted junctional strands, whereas the permeable discontinuous zonules found higher in the epithelium showed a meandering pattern of broken strands.Our observations indicate that (1) Sertoli cell junctional complexes form near the young germinal cells at the base of the seminiferous epithelium and break down near the older germinal cells toward the apex; (2) the various patterns and orientations of the junctional strands reflect, respectively, the different stages of disintegration of the occluding zonules and the conformation of the mature Sertoli cell to the irregular contours of the germinal cells; (3) there is no relationship between permeability and junctional strand orientation; and (4) the cellular contacts between Sertoli cells and germinal cells situated below the blood‐testis barrier may represent the early stages of formation of junctional elements which ultimately become incorporated into the Sertoli cell junctional complex.