bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic histology of the antral epithelilum in the mouse stomach: IV. Ultrastructure and renewal of gland cells
Authors: Lee E. R. , Leblond C. P. 
Published: February 2005

AbstractThe renewal of gland cells was investigated by three‐dimensional reconstruction of typical mucous units of the pyloric antrum using electron microscopy and 3H‐thymidine radioautography in 3 to 4 month‐old CD1 mice.Based on analysis of 42 units, the average gland measured 31 μm in length and was composed of 37 (mucous) gland cells with eight enteroendocrine cells scattered among them. The gland neck cells located close to the isthmus showed the cytoplasmic and nuclear features characteristic of differentiating cells. The mid‐gland cells occupying the central portion of the gland appeared to be at a more advanced stage of development and completing differentiation. The gland base cells comprising the blunt end of the gland were fully mature. To quantify the renewal process, the percent of gland cell nuclei carrying label was determined at several times following 3H‐thymidine administration. The rate of proliferation was found to be greatest in the gland neck, lower in the mid‐gland, and even lower within the gland base. Furthermore, the isthmus contributed to gland‐cell renewal by providing an estimated 12.4 cells per day. Labeled cells migrated toward the blunt end of the gland. The migration rate became progressively slower with their descent, and many cells were lost along the migration pathway, mainly in the gland neck. The loss took place without being preceded by gradual cell degeneration, but occurred as a result of rapid extrusion to the lumen or, less frequently by pyknosis, which could be followed by phagocytosis.It is concluded that the rapid rate of mitosis within the isthmus and gland neck generates a pressure causing downward migration of the cells toward the blunt end of the gland. The rate of migration, however, gradually diminishes as cells descend into the gland, presumably owing both to decreasing proliferation rate and to cell loss. Thus, while cells migrate down toward the gland base, many are lost before reaching it. This sequence is decribed as “the cascade pattern” of renewal.
Analysis of gland cell behavior: Appendix to the dynamic histology of the antral epithelium in the mouse stomach
Authors: Nadler N. J. 
Published: February 2005

AbstractThe origin, route of migration, and ultimate fate of mucous gland cells in mouse antral units have been described in the preceding article. Three regions of the mucous gland, consisting of gland neck cells, mid‐gland cells, and gland base cells, respectively were defined; and the renewal events in each of these regions were studied. In this article, the data obtained by Lee and Leblond (1985) were subjected to a mathematical analysis to obtain additional information about the rate of loss of cells. Calling each anatomical division a compartment, and utilizing the available histometric knowledge concerning the number of cells and the turnover of labeled cells in each compartment, a set of equations was developed, assuming a steady state, for which solutions yielded the number of cells lost from each compartment per unit time.
Early implantation stages in the marmoset monkey (Callithrix jacchus)
Authors: Moore H. D. M. , Gems Sara , Hearn J. P 
Published: February 2005

AbstractThe morphology of the initial stages of implantation in the marmoset monkey (Callithrix jacchus) was studied by obtaining embryos and associated endometrium at timed intervals after ovulation. Estrus cycles were detected by measuring daily levels of plasma progesterone. Following a short follicular phase, circulating levels of progesterone above 20 ng/ml were taken as representing day 1 after ovulation. On this basis, single, twin, and triplet embryos were recovered from six perfused‐fixed females on days 13, 16, 19, 23, and 29 after ovulation and prepared in resin for light microscopy. Early implantation stages, 13 and 16 days after ovulation, were characterized by the intrusion of syncytial trophoblast between epithelial cells of the endometrium with minimal cellular damage. Some hyperplasia of epithelium at the margin of the implantation site was evident. The consolidation of the initial attachment was achieved by an increase in syncytial trophoblast underlying the inner cell mass of the embryo which rapidly surrounded and breached maternal capillaries. Although initially separate, the chorions of twin or triplet embyros started to fuse by day 19 after ovulation. This process was complete by day 29 such that embryos shared a common uterine exocoelom surrounded by continuous trophoblast. It was concluded that implantation in the marmoset monkey commenced on days 11–12.5 after ovulation and involved an intrusive mechanism. Although trophoblast penetration of endometrium was superficial, maternal capillaries were tapped at an early stage of implantation. The fusion of chorions of twins and triplets first occurred around day 19 after ovulation.
Postnatal development of “Synaptic” ribbons and spherules in the guinea pig pineal gland
Authors: Banks J. C. , Dalgleish A. E. , Vollrath L. 
Published: February 2005

AbstractPrevious studies have shown that the functionally enigmatic pineal “synaptic” ribbons are structurally a heterogeneous group of organelles consisting of rodlike ribbons sensu stricto, spherules, and intermediate forms. As ribbons and spherules react differently under various experimental conditions, these organelles were studied qualitatively and quantitatively during the postnatal period in guinea pigs. It was found that the pinealocytes were highly differentiated at birth and contained all three forms of “synaptic” structures. Ribbons and intermediate forms were more abundant than spherules and exhibited a striking increase in number on postnatal days 1 and 2; this increase was followed by a distinct trough and by a second peak at days 12 and 13, after which their numbers declined to reach adult levels by day 20. The spherules were small in number at birth and did not show the large immediate postnatal increase observed for the ribbons and intermediate forms. Instead there was a steady numerical increase up to day 12 (absolute number) or day 15 (relative numbers), followed by a decrease to adult level by day 20. Whereas during the early postnatal period (days 1 to 3) the majority of pinealocytes were characterized by ribbons and intermediate forms, with increasing age spherule‐bearing pinealocytes increased in number. As ribbons and spherules were usually not found in the same pinealocyte, the present findings are interpreted to mean that ribbons and spherules characterize different types of pinealocytes showing an inverse numerical development postnatally. Developmentally intermediate forms behave like ribbons.
Motor innervation of intrafusal fibers in rat muscle spindles: Incomplete separation of dynamic and static systems
Authors: Walro Jon M. , Kucera Jan 
Published: February 2005

AbstractDistributions of 53 motor axons to different types of intrafusal fibers were reconstructed from serial 1‐μm‐thick transverse sections of 13 poles of spindles in the rat soleus muscle. The mean number of motor axons that innervated a spindle pole was 4.1. Approximately 60% of motor axons lost their myelination prior to or shortly after entry into the periaxial fluid space of spindles. Motor innervation to the juxtaequatorial portion of nuclear bag fibers (particularly the bag1) consisted of groups of short, synaptic contacts that were terminations of thin, unmyelinated axons. In contrast, motor endings on both the bag1 and bag2 fibers were platelike in the polar intracapsular region. Chain fibers had a single midpolar platelike ending. The ratio of motor axons that innervated the bag1 fiber exclusively to axons that innervated bag2 and/or chain fibers was 1:1. However, one‐fourth of motor axons coinnervated the dynamic bag1 fiber in conjunction with static bag2 and/or chain fibers. Thus the complete separation of motor control of the dynamic bag1 and static bag2 intrafusal systems observed in cat tenuissimus spindles is neither representative of the pattern of motor innervation in all other species of mammals nor essential to normal spindle function.
Implantation in the rhesus monkey: Endometrial responses
Authors: Enders Allen C. , Welsh Alerick O. , Schlafke Sandra 
Published: February 2005

AbstractIn this continuing series of studies of implantation in the rhesus monkey, eight specimens, ranging in gestation age from 9.5 days to 16.5 days after ovulation, were examined with a focus on localized modifications in the endometrium as a response to implantation. Additionally, evidence of continuing changes in early pregnancy was provided by three specimens at the end of the first month of gestation (days 24, 28, and 35). The responses of the endometrium to pregnancy start with a localized accumulation of stromal eosinophils, which is rapidly followed by epithelial plaque formation in the basal cells of the luminal epithelium and gland necks. Plaque cells hypertrophy, develop marginal dense granules, and accumulate glycogen. They form a pad underlying the margins but not the central zone of the implantation site. However, some degenerating plaque cells are found as early as day 15; and little more than a region of leukocytic infiltration remains of the plaque by day 35. Shortly after the plaque response is initiated there is a striking subepithelial edema surrounding the plaque, and the venular capillaries enlarge by engorgement and by endothelial hyperplasia. The endothelial cells subsequently hypertrophy, resulting in a largely columnar endothelium. There is a localized decidual cell response, consisting of an increase in rough endoplasmic reticulum and in filaments, but only a moderate amount of hypertrophy of these cells. Endometrial granular cells become more conspicuous in the area as they accumulate glycogen. Patches of large pale cells appear in the lumen and walls of arterioles subjacent to the implantation site, but the cytology of these cells provided insufficient clues to their origin (cytotrophoblast?). Although the endometrial responses described are impressive and diverse, their advantages to the organism are not obvious. The hypertrophy of the anastomotic capillary bed that accompanies plaque formation may well provide an extensive vascular network available to the developing trophoblastic lacunae. The role of endometrial granular cells, decidual cells, and even plaque cells may be more related to their largely unexplored secretory activity than to their physical contribution to the formation of the basal plate.
Ultrastructural characterization of epithelial cell membranes in normal human conducting airway epithelium: A freeze‐fracture study
Authors: Carson Johnny L. , Collier Albert M. , Knowles Michael R. , Boucher Richard C. 
Published: February 2005

AbstractCell membranes of normal human nasal and tracheal epithelium were characterized by means of freeze‐fracture preparations. These investigations illustrated a predictable variability in the distribution of membrane‐associated particles on PF‐faces of different cell types and in different regions of the same cell. Details of the fine structure and variability of tight junctional complexes in different cell types are presented as are ultrastructural perspectives of cell membrane involvement in ciliogenesis and in mucus secretion. Because ciliogenic profiles and nascent tight junctional complexes were observed more frequently in nasal epithelial cells, these features provided markers of cellular differentiation. Based on the frequent appearance of such indicators, these observations suggested that cell turnover may be more rapid in the region of the nasal turbinates than in the trachea. There was no appreciable evidence of ultrastructural variability between the epithelial cell membranes of similar cell types in the upper and lower respiratory tract.
Light‐microscopic stereology for the study of the ventral and dorsal prostates of the syrian hamster: Strategy, techniques, and applications
Authors: Buzzell Gerald R. 
Published: February 2005

AbstractA stereological approach to studying the architecture of the ventral and dorsal prostates of the Syrian hamster is described. In this approach, the prostate is considered to consist of acinar and interacinar compartments. The acinar compartment is divided into luminal, epithelial, lamina proprial, and muscular stromal compartments. Volume fractions of acini and interacinar tissue are calculated with reference to the volume of the gland; those of the acinar components are calculated with reference to the acinar volume. Volume fractions are determined from point counts. The surface fraction of the secretory epithelium is determined from intercept counts, with reference to the volume of the epithelium. By assuming that the acini are cylindrical, the acinar length fraction is calculated with reference to the volume of the gland. Absolute values for the volumes of different components, epithelial surface area, and acinar length can be determined from the weight of the gland, its specific gravity, and the volume fraction of that component, or epithelial surface fraction, or acinar length fraction, respectively. Finally, from these values and assuming a cylindrical shape for acini, characteristics of the typical acinus, including its radius, the thicknesses of its epithelium, lamina propria, and muscular stroma, and the amount of mucosal folding can be calculated from simple geometrical formulae. This approach is illustrated from a consideration of the ventral and dorsal prostates of 20‐week‐old Syrian hamsters.
An experimental analysis of the developmental capacities of distal parts of avian leg buds
Authors: Brand B. , Christ B. , Jacob H. J. 
Published: February 2005

AbstractThe development, differentiation, and pattern formation of isolated distal parts of avian leg buds that had grown ectopically on the chorioallantoic membrane (CAM) or in the coelomic cavity were studied. The grafts grown on the CAM invariably gave rise to cartilage and soft connective tissue. In some cases muscle tissue was also found. The CAM grafts did not undergo overt morphogenesis and pattern formation. A high percentage of grafts grown in the coelomic cavity showed a close approximation to normal limbs. The presence of proximal structures depended on the stage of development of the donor at the time of the operation, on the size of the grafts, and on the site to which the graft was attached within the coelom. The presence of anteroposterior structures depended on the shape of the graft. The pattern formation of this axis was found to be independent of the presence of the zone of polarizing activity at the proximal posterior border of the bud. The distance from the tip of the bud to the line of most distal colonization by myogenic cells was determined. The speed of migration of the myogenic cells can be considered to be constant. In muscleless legs, tendons developed at the levels of the phalanges and the tarsometatarse. They degenerated, however, in the absence of muscle from day 9 on, from proximal to distal areas. CAM grafts as well as coelomic grafts were well vascularized. The endothelial cells of the blood vessels were of host origin. In coelomic grafts, nerves were present with Schwann cells of host origin. The nerves and blood vessels showed a distribution that resembled that in normal legs.
Three‐dimensional reconstruction and quantitative analysis of rat lung type II cells: A computer‐based study
Authors: Young Stephen L. , Fram Evan K. , Craig Brenda L. 
Published: February 2005

AbstractThe three‐dimensional structure of alveolar epithelial type II cells was imaged using a computer‐based system designed for reconstruction and quantitative analysis of serially sectioned specimens. Six type II cells were reconstructed from serial ultrathin sections of lungs from two Sprague Dawley male rats and the results were compared to standard morphometric estimates of type II cell compoition from five other Sprague Dawley male rats. A minor portion of the type II cell surface was in contact with the alveolar airspace while most of the cell surface was embedded in the alveolar septal interstitium. The type II cells contained multiple Golgi regions located close to the nucleus. Mitochondria formed a few branching filamentous networks extending throughout the cell. The reconstructed cells appeared to represent a homogeneous population having fractional volumes of intracellular organelles very similar to those found by morphometric techniques. The spatial distribution of secretory organelle volume suggests that the organization of this cell type reflects an ordered progression of secretory particle maturation which is consistent with earlier hypotheses of lamellar body assembly.
Long‐term comparative effect of cholecystokinin and gastrin on mouse stomach, antrum, intestine, and exocrine pancreas
Authors: Balas D. , Senegas‐Balas F. , Pradayrol L. , Vayssette J. , Bertrand C. , Ribet A. 
Published: February 2005

AbstractMice were injected three times a day for 12 days with 300 μg/kg body weight of gastrin G17 or 37.5 Ivy dog U/kg body weight of CCK or saline. Other mice were also injected four times an hr for 1 hr with 7.5 μ/kg of gastrin, nine Ivy dog U/kg of CCK or saline; 1 hr before killing, they were injected with tritiated thymidine to evaluate the labelling indices in peptic, antral, duodenal, jejunal, and ileal mucosae. Four hours after the first injection of the two peptides, the peptic labelling indices increased while those of intestinal mucosa increased 8 hr after these injections. Long‐term injections of CCK had a trophic effect on secretory cells of the digestive tract: the number of gastric zymogenic cells, Paneth cells, and the mucous cells of Brünner glands were hypertrophied. The pepsin, amylase, chymotrypsin, and lysozyme activities increased in stomach, exocrine pancreas, and intestine, respectively. Neither parietal cells nor intestinal enterocytes and hydrolase activities were affected. The trophic effect of long‐term injections of gastrin is confirmed on parietal cells and exocrine pancreatic parenchyma and is demonstrated in Paneth cells. Confirming cytological results, pancreatic lipase and amylase activities and intestinal lysozyme activity were increased after gastrin. Although CCK and gastrin have a structural analogy, these two peptides did not affect the same cellular types. A specific action of CCK on the main secretory cells of the digestive mucosa is demonstrated.
Effects of 1‐hydroxyethylidene‐1, 1‐bisphosphonate (HEBP) on the formation of dentin and the periodontal attachment apparatus in the mouse
Authors: Beertsen W. , Niehof A. , Everts V. 
Published: February 2005

AbstractThe effects of the bisphosphonate HEBP on dentin formation and the structural relationship between the dentin and the developing periodontal attachment apparatus have been studied in the continuously growing mouse incisor. It was observed that HEBP (in doses ≥ 8 mg P/kg b.w/day) not only inhibited the deposition of mineral crystallites in newly formed dentin matrix, but also entirely prevented the formation of a layer of acellular root cementum. It was further noticed that the drug interfered with the deposition of 3H‐serine‐containing substances at the predentin‐dentin border. This was not always accompanied by an inhibition of dentin mineralization, thereby suggesting that 3H‐serine‐containing proteins (presumably phosphoproteins) do not play a critical role in the deposition of mineral layers onto previously formed ones. The absence of a cementum layer did not prevent the developing periodontal ligament from establishing matrix‐to‐matrix connections with the root‐analogue dentin. Collagen fibrils of the ligament intermingled with those of the mantle dentin, which in contrast to teeth not exposed to the drug were clearly visible and not masked by electron‐dense matrix components. Finally, it was found that the drug had distinct effects on the formation of root‐analogue and crown‐analogue dentin. Whereas during the course of the experiment the odontoblasts along the crown‐analogue aspect of the tooth continued to produce circumpulpal dentin matrix, those along the root‐analogue aspect of the tooth did so only when the mantle dentin layer had been mineralized prior to HEBP administration. This phenomenon is interpreted as being indicative of fundamental differences between the formation of crown and root dentin.
Plasma membrane‐associated vesicles in retinal capillaries of the rat
Authors: Gordon Sheldon R. , Essner Edward 
Published: February 2005

AbstractThe structure and function of abluminal vesicles in endothelial cells of rat retinal capillaries was examined using glutaraldehyde—tannic acid fixation and the hemeproteins—horseradish peroxidase, microperoxidase, and lactoperoxidase—as tracers. Numerous vesicles, delimited by a tannic acid—positive membrane, were distributed along the abluminal front. Other vesicles were arranged in clusters and chains or tubule‐like structures. Such vesicles were not found in the vicinity of the capillary lumen. When the retina was exposed to hemeproteins, either in vitro or after intravitreal injection, the abluminal vesicles became labeled with tracer reaction product. Apparently “free” vesicles and tubules seen in tangential sections through the basal lamina were also labeled, suggesting that they were in continuity with the plasma membrane in another plane of section. No enzyme reaction product was present in the capillary lumen. Peroxidase‐positive multivesicular bodies were observed, suggesting that some protein was endocytosed and directed to lysosomes where it was presumably degraded. The results suggest that abluminal endothelial vesicles represent pits or invaginations of the plasma membrane and, as such, are not involved in the transendothelial transport of protein from the perivascular space to the capillary lumen. Tannic acid treatment revealed a population of similar vesicles associated with the plasma membrane of pericytes. After exposure to hemeproteins, enzyme reaction product was localized in these vesicles and in a few multivesicular bodies. The results suggest that the majority of these vesicles are in continuity with the plasma membrane and are not involved in endocytosis.
The effect of atrophy, hyperplasia, and keratinization accompanying the estrous cycle on Langerhans' cells in mouse vaginal epithelium
Authors: Young William G. , Newcomb Guy M. , Hosking Annette R. 
Published: February 2005

AbstractThe morphology and numbers of Langerhans' cells vary in epithelia with different patterns of hyperplasia and keratinization. Langerhans' cells stained for ATPase were compared at five phases of the estrous cycle in murine vaginal epithelium. The cells were more dendritic and sparsely distributed with hyperplasia and were less dendritic and more densely distributed with atrophy. Greater numbers of the cells did not accompany keratinization at estrus. Ultrastructurally, three types of Langerhans' cells were discriminated. The first type, active in protein synthesis and phagocytosis, was commonest in sloughing and atrophic epithelium. The second type, containing accumulated and dispersed, electron‐dense bodies presumed to be lysosomes, predominated in hyperplastic epithelium. The third, a mature resting cell, was found only after keratinization was complete. This study shows that Langerhans' cells in murine vaginal epithelium vary in morphology and numbers with the epithelial changes of the estrous cycle which may relate to their immunological role, but does not support the contention that their distribution is important for keratinization.