bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of various fixative‐buffer combinations on lung fine structure
Authors: O'Hare Karen Hitchcock , Braunschweig Ralph Jon 
Published: February 2005

AbstractA variety of fixatives, buffers and fixation procedures were compared in rat and squirrel monkey lung in an attempt to preserve optimally both the cytologic details of pulmonary parenchyma as well as the acellular alveolar lining layer. In initial experiments utilizing the fixative of Ito and Karnovsky ('68), an electron‐dense deposit was observed on the alveolar surface. Experiments were carried out in an attempt to determine what component of this fixative was responsible for the reaction product observed. In addition, immersion fixation of tissue blocks was compared to the whole lung fixation method of Kikkawa ('70). Kikkawa ('70) achieved excellent preservation of the acellular alveolar lining layer by such a fixation technique.In all lungs examined, whenever a phosphate buffer was utilized with primary aldehyde fixation, an electron‐dense precipitate was observed on the luminal surfaces of the type I and II pulmonary epithelial cells. Additional sites of reaction product were pinocytotic vesicles of the type I cells and membranous arrays within the alveolar lumen. Such deposits were never observed when a sodium cacodylate buffer was used. No such granules were observed in areas of lung where the acellular alveolar lining layer had been preserved.The implications of these findings with regard to lung histochemical procedures and the possible relationship of these phosphate buffer‐dependent granules to the surfactant system are discussed.
Granular cells in the juxtaglomerular apparatus in perinatal rats
Authors: Eguchi Y. , Yamakawa Michiko , Morikawa Y. , Hashimoto Y. 
Published: February 2005

AbstractGranular cell indices (GCI; Dunihue and Robertson, '57) in kidneys of fetal and newborn rats were determined by examining sections stained with Bowie's technique. Some fetuses were delivered prematurely by Caesarean section a day earlier than the expected delivery, and were then nursed by a foster mother. Similarly, postmature Caesarean newborn rats were obtained; retention one day beyond the normal gestation was induced by maternal progesterone injections.The GCI was strikingly increased within a day after birth, followed by an immediate decrease thereafter. This was also observed in both premature and postmature newborn rats. It seems that this temporary increase of the GCI is not attributable solely to the age of rat, but follows only the separation from the maternal environment.
The postnatal development of high‐endothelial venules in lymph nodes of mice
Authors: Van Deurs B. , Röpke C. 
Published: February 2005

AbstractThe postnatal development of high‐endothelial venules (HEvenules) in popliteal lymph nodes of normal and athymic mice was studied by light and electron microscopy.In the normal mice, undifferentiated postcapillary HEvenules are already present at birth. During the first four days after birth, ribosomes and mitochondria in the endothelial cells of the venules become more numerous, and the endoplasmic reticulum and in particular the Golgi complexes enlarge. At day four lymphocyte diapedesis through the venules becomes apparent. From the tenth day the HEvenules are structurally mature. However, diapedesis activity still increases till about a month postnatally. In mice with congenital aplasia of the thymus (nude mice) and in neonatally thymectomized mice the development of the HEvenules is similar to that in normal mice. In the athymic mice both lymphocytes and granulocytes migrate through the walls of the HEvenules. However, the blood level of lymphocytes in these mice is far below the value in normal mice.It is concluded that the development of the HEvenules during the first month of life is independent of the blood level of lymphocytes.
The immune system of the nine‐banded armadillo (dasypus novemcinctus, linn)
Authors: Purtilo David T. , Walsh Gerald P. , Storrs Eleanor E. , Gannon Carman 
Published: February 2005

AbstractThe armadillo is rapidly emerging as an animal for biomedical research. A morphological study of the immune system of the armadillo was undertaken to try to demonstrate a possible defect in the morphogenesis of the lymphoid organs that could account for their susceptibility to leprosy. Blood from 20 domesticated adult armadillos revealed lymphocytes predominated among circulating leukocytes in the majority of animals, whereas in wild animals neutrophils predominated. Necropsies revealed well‐developed thymus glands and the thymus‐dependent areas in lymph nodes and spleens contained abundant lymphoid cells. Hence, we conclude that the susceptibility of the armadillo to leprosy cannot be explained on a morphological basis.
Malorientation of mitotic figures in the early lens rudiment of aphakia mouse embryos
Authors: Zwaan Johan , Kirkland Barbara M. 
Published: February 2005

AbstractIn early embryonic epithelia most cell divisions are oriented with their cleavage furrows perpendicular to the free surface of the tissue. This results in the generation of two daughter cells, which are equivalent with regard to their apical surface. Mitotic figures, in which the long axis through the centers of the chromosome plates (chromatin masses) is perpendicular to the surface, are seen only occasionally.The lens placode and early lens cup of mouse embryos homozygous for the gene aphakia show significantly greater numbers of maloriented mitoses than normal control lenses. The axis connecting the centers of the chromosomal plates is frequently perpendicular or oblique to the surface. This may result in the production of daughter cells, which are unequal as far as their position at the tissue surface is concerned.Later, the lumen of the mutant lens vesicle fills up with cells, which are apparently released from the lens epithelium. Further development of the lens and the eye is grossly disturbed.The release of these cells may be a consequence of the malorientation of their divisions, or both may be the result of a defect in the spatial orgnization of the lens tissue, possibly due to abnormal cellular adhesion.
Kinetics of pulmonary epithelial proliferation during prenatal growth of the mouse lung
Authors: Kauffman Shirley L. 
Published: February 2005

AbstractAutoradiographic methods were used to analyze cell kinetics in peripheral epithelium of the fetal mouse lung, days 15‐18. The 3H labeling index decreased in proportion to increases in fetal lung and body weight from day 15 to day 18. Cell‐cycle determination estimated from the percent of labeled metaphases at intervals after 3H thymidine injection showed the shortest cell‐cycle time (12.25 hours) on day 15 during the precenal stage of growth. Total cycle time (Tc) increased by approximately one hour on each subsequent day. Between days 15 and 16 Tc increased due to a 1‐hour increase in the post mitotic interphase (G1); thereafter increases in Tc could be ascribed almost entirely to lengthening of the DNA synthetic period. A comparison of cell‐cycle time in central and peripheral tubules of the same lungs on day 15 showed a slower cell cycle in the central tubules than in the peripheral branches. An estimate of the growth fraction (GF) on each day based on calculated and observed cell‐cycle times showed that GF was 1 on days 15 and 16, decreasing to 0.69 on day 17 and 0.27 on day 18. Thus cell‐cycle time increases with lung maturation and it increases from peripheral to central zones of the bronchial tree. The greater part of the observed decline in growth rate as the prenatal phase of growth is completed was due largely to a decrease in the fraction of cells in the cell cycle.
Morphological studies on the synthesis of secretory granules in convoluted tubules of mouse submandibular gland
Authors: Kaiho Masayoshi , Nakamura Toshikazu , Kumegawa Masayoshi 
Published: February 2005

AbstractThe synthesis of zymogen‐like secretory granules in convoluted tubules of mouse submandibular gland (SMG) was investigated by histometry, light microscopy and electron microscopy. In normal males secretory granules in the SMG increased greatly from 25 days after birth and reached a maximum level 50 days after birth. Castration of adult male mice markedly decreased the level, but it was completely restored by testosterone administration. A parallel was found between change in the granule level and the amount of rough endoplasmic reticulum (RER) in the convoluted tubular cells during development or after various treatments. Development of the Golgi apparatus was also observed in the cells when the granules increased. Both the increase in the granules and in the RER induced by testosterone were prevented by actinomycin D or puromycin. These results indicate that the granule contents are synthesized on the RER under the control of testosterone, and then condensed in the Golgi apparatus.
Morphogenesis of the carpal elements in the regenerating forelimb of adult Notophthalmus viridescens viridescens
Authors: Benzo Mary M. , Benzo Camillo A. , Manner Harold W. 
Published: February 2005

AbstractThis study is concerned with the morphogenesis of the carpal elements in the regenerating forelimb of the adult newt. Blastema cells surrounding the remnant bony stumps begin to differentiate into cartilage on the twentieth post‐amputation day. Subsequently, masses of cartilage build up from the radial and ulnar stumps. The radial mass is larger and differentiates more rapidly than the ulnar mass. By the fifty‐fifth post‐amputation day, the eight basic carpal elements are formed, with fusion of two of the units, intermedium with ulnare, occurring by the seventieth day. The complexed regenerate possesses the seven carpal elements characteristic of the normal adult limb. The present results show that during limb regeneration in the adult newt the carpal elements are restored to their original number and position and that the pattern of such carpal differentiation proceeds in a proximodistal direction influenced by the stump remnants of the radius and ulna.
Cellular mechanisms involved in cyclic stromal renewal of the uterus. III. Cells of the immune response
Authors: Padykula Helen A. 
Published: February 2005

AbstractThe principal cell types associated with the humoral immune response (monocyte‐macrophages, lymphocytes, and plasma cells) are numerous in the endometrial stroma of the uterus during the first four postpartum days in two types of mammals, the marsupial North American opossum and the eutherian albino rat. This transient cellular differentiation coincides with the physiologic period of rapid uterine regression which includes massive reduction in the amount of extracellular stromal material. In addition, heterophils and eosinophils, cell types also known to be associated with phagocytic and immunologic activity, appear in the stroma during the first two postpartum days; their presence may, however, be associated more directly with the postpartum estrus that occurs on day 1 postpartum than with endometrial regression. Thus, the five cell types, which are known in pathologic conditions to be components of an inflammatory response to a foreign antigen, are conspicuously present in the normal regressing endometrium. Furthermore, there is ample ultrastructural evidence of frequent macrophagic‐lymphocytic interaction, transformation of lymphocytes, and active secretion by plasma cells during this early postpartum period.An hypothesis has been derived by uniting this new description of endometrial stromal cell differentiation with the existing literature on uterine collagenase activity, an important feature of postpartum regression (reviews by Gross, 1974; Harris and Krane, 1974). It is based on the assumption that during regression the extracellular action of neutral collagenase (and possibly other extracellular proteases) release new antigenic sites in proteins located in the ground substance. In the case of collagenase, these transient antigenic sites would arise at the locus of enzymic cleavage as well as from the subsequent denaturation of the fragments of the collagen molecule. This endogenous antigenic stimulus would be strong and temporary, and would lead to the cellular manifestations of the transient humoral immunologic response which are evident in the regressing stroma of these two mammals. This humoral immune reaction may be one of the regulatory mechanisms involved in the cyclic renewal of the extracellular compartment of the uterine stroma.
Mechanical properties and histology of cortical bone from younger and older men
Authors: Evans F. Gaynor 
Published: February 2005

AbstractTensile breaking load, strength, strain, modulus of elasticity and density plus the histological structure at the fracture site, were determined for 207 standardized specimens of cortical bone from the embalmed femur, tibia, and fibula of 17 men from 36 to 75 years of age. The men were divided into a younger group (41.5 years old‐avg) and an older group (71 years old‐avg). Specimens from younger men had a greater average breaking load, strength, strain, modulus and density than those from older men. The percentage of spaces in the break area was greater in specimens from older men, but specimens from younger men had a slightly greater percentage of osteons, osteon fragments, and interstitial lamellae. The number of osteons/mm2 and of osteon fragments/mm2 was greater in specimens from older men but the average area/osteon and area/osteon fragment was greater in specimens from younger men. Thus, there are quantitative and qualitative differences in the histological structure of bone from younger and older men. Differences in the tensile properties of bone from younger and older men can be explained by histological differences in the bone.
Recovery of rat prolactin cells following cessation of estrogen treatment
Authors: Shiino Masataka , Rennels Edward G. 
Published: February 2005

AbstractEstrogen treatment for one month in female rats caused some regression of somatotrophs, but induced an increase in the number of prolactin cells and caused these cells to hypertrophy. These stimulated prolactin cells showed extensive development of the granular endoplasmic reticulum which was often arranged in concentric whorls (Nebenkern). Most of the prolactin cells contained a small number of mature granules which were smaller in size than those of prolactin cells in control animals. These prolactin granules were round in sectioned profile and closely resembled the secretory granules of normal somatotrophs.At five and ten days after the suspension of estrogen treatment, many prolactin cells contained numerous secretory granules of various sizes ranging from 150–500 nm. Only occasional granules in these cells were as large as 750 nm, and only the largest of the granules exhibited the irregular shape which is characteristic of mature granules in normal prolactin cells. Fifteen days after the cessation of estrogen injection most prolactin cells exhibited numerous secondary lysosomes. At this time the mature secretory granules were similar in morphology to those of normal prolactin cells.From the fact that the somatotrophs appeared not to be stimulated by the estrogen treatment we find it difficult to accept the concept that somatotrophs cna undergo transformation into prolactin cells.
The skin of the giraffe
Authors: Dimond Robert L. , Montagna William 
Published: February 2005

AbstractThe skin of the giraffe has the same general histological structure as that of other mammals, but there are notable features. The skin is heavily pigmented with the epidermis, pilary canals, and the outer cell layer of the apocrine duct richly melanized. Furthermore, melanotic dendritic cells are frequently found in the sebaceous glands, the entire length of the external root sheath, and the secretory tubules of the apocrine glands. The thick skin has a papillary dermis that extends to just beneath the secretory coils of the apocrine glands and bulbs of hair follicles and an equally thick reticular layer below these structures. The hair follicles do not grow in clusters, and with some regional variations, have associated sebaceous glands, apocrine glands, and arrectores pilorum muscles. Only the large hairs have a prominent medulla. In such specialized regions as the eyelids, nose, and lips, the apocrine glands are surrounded by cholinesterase‐reactive nerves but the glands on the general body surface are not. The only specialized nerve receptors are hair follicle end organs found on every hair of the eyelids, nose, and lips, but only rarely elsewhere.
A light and electron microscopic investigation of the hepatic parenchyma of the adult newt, Notophthalmus viridescens
Authors: Haar Jack L. , Hightower James A. 
Published: February 2005

AbstractThis light and electron microscopic study demonstrates that the liver of the adult newt, Notophthalmus viridescens, consists of a mass of hepatocytes interrupted by blood sinusoids which allow blood to percolate through the parenchyma. The plates separating adjacent sinusoids are usually two or more cells thick and the bile canaliculi lie between 2–6 neighboring cells. Fine structural characteristics of hepatocytes include abundant lipid and glycogen inclusions. Melanophores with developing melanosomes are situated throughout the hepatic parenchyma.
Localization of transferrin on the surface of the human placenta by electron microscopic immunocytochemistry
Authors: King Barry F. 
Published: February 2005

AbstractDuring the course of gestation, a large amount of iron is transferred rapidly and unidirectionally from mother to fetus across the placenta. It has been postulated that one of the first steps involved in placental iron transfer involves binding of the maternal transferrin‐iron complex to the surface of the placenta and the subsequent removal of iron and release of transferrin back into the maternal circulation. To determine if transferrin is present on the surface of human placental villi, two different immunocytochemical methods have been used: (1) an unlabeled antibody, peroxidase‐antiperoxidase (PAP) method utilizing rabbit antiserum to human transferrin, goat anti‐rabbit IgG and rabbit peroxidase‐antiperoxidase complex or; (2) a peroxidase‐labeled antibody method utilizing goat antiserum to human transferrin and peroxidase‐conjugated rabbit anti‐goat IgG. The peroxidase was then localized by incubation in a diaminobenzidine‐hydrogen peroxide medium. Examination of the tissue in the electron microscope revealed the reaction product deposited as discrete patches or particles on the microvillous surface of human syncytial trophoblast. Controls using non‐immune serum or an antiserum adsorbed with purified human transferrin showed no reaction product on the surface. The results provide morphological confirmation for the presence of transferrin on the surface of human syncytial trophoblast lining the maternal blood spaces.
A correlative histofluorescence and light microscopic study of the formation of the sympathetic trunks in chick embryos
Authors: Kirby M. L. , Gilmore S. A. 
Published: February 2005

AbstractThe appearance and development of the primary and secondary sympathetic trunks in staged chick embryos was studied using the Falck‐Owman histochemical method for the demonstration of primary monoamines. The earliest appearance of catecholamine (stage 20) was in individual fluorescent cells located in the region of the dorsal root ganglia about two stages prior to the formation of primary trunk aggregates. These cells are believed to be sympathetic precursor cells and correspond to formaldehyde‐induced fluorescent cells observed in recent explantation experiments. Aggregates of fluorescent cells had formed bilaterally dorsolateral to the aorta at stage 22. These aggregates became continuous to form primary trunks by stage 24. The secondary sympathetic trunks were first seen in stage 25 and appeared to form at least partially by dorsal migration of cells from the primary trunks. Fluorescent cell processes were first observed at this stage. Secondary trunk formation was essentially complete by stage 28, and the primary trunks had become small and discontinuous. Definite rami communicantes could be observed by the early part of stage 28 in silver preparations. The significance of the development of two successive trunks in avians is discussed.
Ultrastructure of gallstones produced in mice fed a high cholesterol diet
Authors: Saland L. C. , Napolitano L. M. 
Published: February 2005

AbstractMice fed a high cholesterol‐cholic acid diet for two to six months develop gallstones; these were studied by transmission electron microscopy after glutaraldehyde‐digitonin fixation. Examination of the contents of mouse gallbladders presents views of layered structures and surrounding amorphous material. We interpret these images of gallstones to suggest that they may arise by cohesion of material rich in cholesterol to form more ordered structures. Gallbladder contents of mice fed the diet for five to six months were found to contain occasional crystals and rectangular areas similar to those observed in thin sections of human gallstones (unpublished observations). Recent findings that human gallstones can be dissolved with chenodeoxycholic acid are discussed, with reference to their applicability to studies of gallstones in mice.
Electron microscopic autoradiographic analysis of the uptake and intracellular transport of H3‐leucine by the rat submandibular gland acinar cells in tissue slices
Authors: Bogart Bruce Ian 
Published: February 2005

AbstractUptake of H3‐leucine into secretory product and its subsequent intracellular transport was analyzed by electron microscopic autoradiographic techniques in the rat submandibular gland acinar cells in vitro. The route and kinetic timetable of intracellular transport was established for the acinar cell secretory product by calculating the percent of silver grains and relative grain density associated with the various organelles on a time sequence basis. Radioactivity was first associated with the rough endoplasmic reticulum; then the convex surface of the Golgi apparatus; the concave surface of the Golgi apparatus; and finally with the secretory granules. Comparison of the kinetics of intracellular transport in the rat submandibular gland acinar cell with other established systems revealed only a difference in the exit of radioactivity from the concave surface of the Golgi apparatus.