bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological changes in the midpiece of wooly opossum spermatozoa during epididymal transit
Authors: Olson Gary E. , Hamilton David W. 
Published: February 2005

AbstractSeveral ultrastructural changes were found to occur in the midpiece region of wooly opossum spermatozoa during epididymal maturation. The changes include alterations in mitochondrial morphology, development of structural specializations of the plasma membrane, and acquisition of a prominent extracellular coating. The lamellar membrane network which is wound about the periphery of the mitochondria becomes more densely packed during sperm development and the reticular network of membranes noted in the center of the mitochondria of immature sperm disappears leaving a homogeneous electron dense central zone. During epididymal transit the plasma membrane over the sperm midpiece region shows extensive structural modification. In cross sections of paired spermatozoa the plasma membrane of the midpiece regions shows a very regular, repetitive scalloping. Inlongitudinal sections the scalloping is observed as continuous parallel ridges which extend slightly obliquely to the flagellar long axis. Each ridge appears to be greater in density than the interridge areas. In theepididymis a prominent extracellular coating of dense material is reposited over the midpiece surface; thismaterial is similar in appearance to dense material seen in restricted areas of the epididymal lumen. At the proximal and distal ends of the midpiece the plasma membrane comes into intimate contact with underlying structural specializations and it is suggested that these zones of fusion may serve to preserve regional differences in membrane composition.
Ultrastructural studies of the female breast. I. 9+0 Cilia In myoepithelial cells
Authors: Stirling John W. , Chandler John A. 
Published: February 2005

Abstract9+0 cilia associated with diplosomes were observed in myoepithelial cells of the ductal system in the undiseased, resting, adult female breast. Ciliary diameter was 250 nm, and the longest found was 830 nm. The centrioles comprising the diplosome were 500 nm in length and 160 to 200 nm in diameter. Satellite bodies were associated with the diplosome but there was no rootlet system. Evidence suggested that all myoepithelial cells bear a cilium. The possible functions of the cilia in a sensory role as chemo‐ or mechanoreceptors related to myoepithelial and epithelial activities are discussed.
Actin‐like filaments in the Sertoli cell junctional specializations in the swine and mouse testis
Authors: Toyama Yoshiro 
Published: February 2005

AbstractMicrofilaments at the junctional specializations between adjacent Sertoli cells and between the Sertoli cell and the late spermatid of the mouse and swine testes bind HMM and form arrowhead complexes with a periodicity of about 35 nm. The arrowhead formation is inhibited when the tissues are treated with HMM in the presence of ATP. These observations show that the microfilaments are actin‐like in nature. The functional significance of these filaments in the Sertoli cell is discussed.
Sex differences in Necturus urinary bladders
Authors: Lefevre M. E. , Norris J. , Hammer R. 
Published: February 2005

AbstractWe describe morphological sex differences in urinary bladders of the urodele amphibian Necturus maculosus. The mucosal epithelial cells of bladders from males were tall and contained considerable PAS‐positive material. In scanning electron micrographs of the mucosal surface, epithelial cells from male bladders were well demarcated and were capped with microplicae or with long cilia. The mucosal epithelial cells of bladders from females were low and contained only a small amount of PAS‐positive material; in scanning electron micrographs cell boundaries could not be distinguished and no cilia or microplicae were present. Bladders from males had higher transepithelial potential difference and lower water content than bladders from females. Urine analyses were not significantly different in the two sexes. It is suggested that response to androgens in the male accounts for the observed differences.
Quantitative analysis of cell turnover in the enamel organ of the rat incisor. Evidence for ameloblast death immediately after enamel matrix secretion
Authors: Smith C. E. , Warshawsky H. 
Published: February 2005

AbstractDuring renewal of the enamel organ in the rat incisor cohorts of epithelial cells are transported sequentially through presecretory, secretory and maturation zones to the gingival margin where the life cycles of these cells terminate. This process was examined kinetically by determining the absolute flux of cells within each of these zones of amelogenesis. It was found that the efflux of ameloblasts, stratum intermedium and papillary layer cells from the presecretory zone was about equal to the efflux plus expected growth within the secretory zone. However, between the secretory and maturation zones about 50% more ameloblasts entered the maturation zone than were required to account for the egress at the gingival margin and the expected growth. Since there was no similar imbalance between these zones for papillary layer cells, it was concluded that this discrepancy must represent a 50% reduction in the size of the ameloblast population during the maturation stage of amelogenesis. It was calculated that a little over 25% of the loss occurred immediately at the start of maturation within the region of postsecretory transition and the remaining 25% of the loss occurred throughout the subsequent regions of the maturation zone. In addition to the kinetic analysis graphic reconstructions, or surface maps, of ameloblast nuclei were prepared. These maps illustrated the characteristics of ameloblast nuclear packing within the three zones of amelogenesis and they provided quantitative confirmation that as ameloblasts progress through the maturation zone, there is a loss of cells in an amount predicted by the kinetic analysis.
Fibers in monkey posterior articular nerves
Authors: Gardner Ernest , Lenn Nicholas J. 
Published: February 2005

AbstractThe distribution of axons in the posterior articular nerves in rhesus monkey has been studied in terms of ratio of myelinated to unmyelinated fibers, and size of myelinated fibers. Conduction velocity measurements were also made. The nerves contained 2,000 to 2,200 unmyelinated fibers of 0.2 to 1.2 μm. diameter. They contained 399 to 478 myelinated fibers, varying in size from 1.4 to 12.3 μm. Thus 80 to 85% of fibers in these nerves were unmyelinated. The maximum conduction velocity of 70 to 80 meters per second corresponded to an initial small deflection, with most fibers conducting at slower rates. These results are compared to previous reports which severely underestimated the number of unmyelinated fibers because electron microscope counts were not utilized.It is suggested that pain fibers from the knee joint of monkey make up much of this large population of unmyelinated axons. An unknown number of post‐ganglionic sympathetic fibers is also included in the unmyelinated fiber group.
Spermatogenesis in the Chinese hamster
Authors: Oud J. L. , de Rooij D. G. 
Published: February 2005

AbstractIn this article a description of the process of spermatogenesis in the Chinese hamster is given.Spermiogenesis could be divided into 16 steps. The cycle of the seminiferous epithelium was divided into 12 stages, coinciding with the first 12 steps of spermiogenesis. The relative and absolute duration of the stages was determined. The duration of the cycle of the seminiferous epithelium was found to be 17.0 days.The morphology of the spermatogonia was studied in seminiferous tubules mounted “in toto.” Four classes of spermatogonia could be discerned: undifferentiated A spermatogonia (Ais, Apr, Aal), differentiated A spermatogonia (A1, A2, A3). In spermatogonia and B spermatogonia (B1, B2). It is interesting to note that the last generation of spermatogonia (B2) arises at the beginning of stage 7 and divides to give rise to primary spermatocytes in the second half of this stage; in most other species the last generation of spermatogonia arises in stage 4, giving rise to primary spermatocytes in stage 6.The undifferentiated A spermatogonia were counted in six stages of the cycle, together with the differentiated A, In or B spermatogonia present in the same stages. The results of these cell counts are discussed in detail. One of the conclusions that could be drawn about the behaviour of the Ais and Apr spermatogonia during the cycle of the epithelium was that there is mitotic activity in these cells in several stages of the cycle. It is suggested that this mitotic activity serves to generate the Aal spermatogonia, which after one or more divisions transform into A1 spermatogonia between stages 2 and 8.
Proteolytic dechorionation of annual fish embryos
Authors: Lesseps Roland J. , Gast Elizabeth A. 
Published: February 2005

AbstractIncubation of early embryos of Nothobranchius korthausae in sterile Tris‐buffered pronase with added salts and EDTA results in complete dechorionation, after which development proceeds normally and at the same rate as in control embryos. The time required for dechorionation varies according to the age of the embryo and the concentration of pronase employed.
Granularity of cells in the juxtaglomerular apparatus in fetal rats after maternal nephrectomy or fetal unilateral nephrectomy
Authors: Eguchi Y. , Yamakawa Michiko , Arishima K. , Morikawa Y. , Hashimoto Y. 
Published: February 2005

AbstractGranular cell indices (GCI: Dunihue and Robertson, 1957) in kidneys of fetal rats one day after maternal nephrectomy or fetal unilateral nephrectomy on day 21 of gestation were determined by examining sections stained with Bowie's technique. Maternal nephrectomy induced an extreme increase of GCI in fetal kidneys with increased granularity of cells in the juxtaglomerular apparatus. Fetal unilateral nephrectomy did not cause any significant change.
Ultrastructure of the cat sublingual gland
Authors: Tandler Bernard , Poulsen Jørgen Hedemark 
Published: February 2005

AbstractThe sublingual gland of the cat consists primarily of branched secretory tubules that open into an abbreviated duct system. The simple epithelium that composes the secretory tubules consists of an admixture of mucous and serous cells, with the former predominating. Some secretory tubules are capped by a serous demilune. Regardless of position, almost all serous cells have prominent basal folds and border on at least one intercellular canaliculus as well as on the tubule lumen. Serous cells possess an extensive array of irregular, distended cisternae of rough‐surfaced endoplasmic reticulum that frequently contain dense intracisternal granules. Serous granules are relatively few in number and rarely show evidence of substructure. Mucous cells, which lack basal folds, contain an apical mass of secretory material in the form of partially fused droplets. The duct system is somewhat less ordered than in most major salivary glands; secretory tubules empty into structures resembling intercalated ducts or may be in direct continuity with ducts intermediate in morphology between intercalated and excretory ducts. The absence of striated ducts noted in this study may be correlated with the high sodium content of cat sublingual saliva. The main excretory duct of the sublingual gland closely resembles that of the cat submandibular gland in terms of morphology, but exhibits little of the transport functions reported in the latter duct.
The localization of articular cartilage proteoglycan by electron microscopy
Authors: Shepard Nora , Mitchell Nelson 
Published: February 2005

AbstractRabbit articular cartilage was fixed with glutaraldehyde containing Ruthenium Red or Safranin O to localize proteoglycan. By light and electron microscopy, Safranin O proteoglycan localization is easily obtained. Ruthenium Red stained proteoglycan is easily visualized by electron microscopy. Previous digestion with papain prevented staining by either technique confirming that the material was indeed proteoglycan.Using these methods of proteoglycan identification the sites of attachment to collagen are shown as well as the deposition of proteoglycan about cells of differing vitality and the relationship of proteoglycan to cell membranes.
The thyroid gland of the woodchuck, Marmota monax: A morphological study of seasonal variations in the follicular cells
Authors: Krupp P. P. , Young R. A. , Frink R. 
Published: February 2005

AbstractThe morphology of the thyroid gland of the woodchuck, Marmota monax, was studied during the four seasons of the year. In the spring the thyroid is extremely heterogeneous in appearance. Some follicular cells appear quite active. They contain a well defined Golgi apparatus, abundant large colloid droplets and pseudopodia but few, if any, apical vesicles. Other less active cells have poorly defined rough surfaced endoplasmic reticulum and lack a well developed Golgi apparatus. They do not contain apical vesicles or colloid droplets. Summer thyroids have uniformly small follicles which are lined by high cuboidal cells containing numerous mitochondria, apical vesicles, abundant rough surfaced endoplasmic reticulum, and lipid droplets but few colloid droplets. There is extensive lateral and basal infolding of the cytoplasmic membranes in these cells. In the fall and winter the follicles are larger than in the summer and contain more colloid. Numerous heterogeneous dense bodies appear in the cytoplasm of the follicular cells in the fall and increase in number in the winter when there is an obvious sparsity of such glycoprotein synthetic organelles as Golgi apparatus and rough surfaced endoplasmic reticulum. These morphologic changes are compared with previous studies of thyroid structure and function in other animals and are correlated with the seasonal physiologic activities of the woodchuck.
Ultrastructural alterations in neuroepithelial cells of mouse embryos exposed to cytotoxic doses of hydroxyurea
Authors: Sadler T. W. , Cardell R. R. 
Published: February 2005

AbstractDeveloping neuroepithelial cells from the cranial region of neural folds were examined at various intervals from 15 minutes to four hours after administration of teratogenic (250 mg/kg) or embryolethal (500 mg/kg) doses of HU to ICR/DUB mice on ninth day of gestation. Thirty percent of surviving fetuses showed exencephaly after the teratogenic dose. The initial ultrastructural change in some neuroepithelial cells occurred within 15 minutes to one hour after treatment with the teratogenic dose and involved a breakdown of polyribosomes into monosomes which were dispersed evenly in the cytosome. At one to two hours, condensation of the cytoplasm and chromatin was observed along with distorted nuclear shape. At two to four hours, cells exhibited extremely condensed cytoplasm and fragmentation of the cells occurred. The affected cells showed pyknotic nuclei and segregation of fibrillar and granular components of the nucleolus. In some nuclei, particularly after treatment with the higher dose of HU, a condensation of the nucleolus was observed. At this stage images were obtained which indicated that neighboring cells phagocytosed the cellular fragments derived from the HU affected cells.
Myogenic cell formation in regenerating rat skeletal muscle injured by mincing I. A fine structural study
Authors: Snow Mikel H. 
Published: February 2005

AbstractThe degenerative and early regenerative events following mincing and autotransplantation of rat skeletal muscle were examined at the ultrastructural level. During the first eight hours after injury, myonuclei undergo pyknosis, mitochondria become enlarged and vesiculated, myofilaments appear less distinct than normal and the sarcolemmata either disappear or become extensively fragmented. Further degeneration of the myofibers progresses slowly until macrophages and polymorphonuclear neutrophils invade the degenerating sarcoplasm between one to four days after mincing. Scattered throughout the minced muscle implant during the first 24 hours after injury are small, viable‐appearing, undifferentiated cells located between the external lamina and degenerating sarcoplasm. Such cells, which are structurally similar to satellite cells seen in uninjured muscle, are believed to be regenerating presumptive myoblasts due to their mesenchymal‐like morphology and sublaminar position. External laminae of the injured muscle fibers do not undergo immediate degenerative changes, but rather persist during the first three to six days as laminar tubes within which spindle‐shaped myoblasts and newly formed myotubes are frequently observed. Examples of regenerating myoblasts in the process of budding‐off from damaged muscle fibers were not observed in this study. Therefore, the evidence suggests that satellite cells are the major source of regenerating myoblasts in skeletal muscle of the rat.
An improved perfusion fixation method for the testis
Authors: Forssmann W. G. , Ito S. , Weihe E. , Aoki A. , Dym M. , Fawcett D. W. 
Published: February 2005

AbstractA reliable and uniform vascular perfusion fixation method for the testis has been developed by using an initial washout solution containing a vasodilator and an anticoagulant. This is followed by a brief fixation with a sodium phosphate buffered formaldehyde‐glutaraldehyde solution of conventional strength, and then a second more concentrated aldehyde fixative solution containing picric acid. The method takes into account some of the unique features of the vascular supply of the male genital tract for its favorable perfusion and fixation. The advantages of this method are: (1) consistently favorable preservation of the testis; (2) simple and inexpensive apparatus; and (3) stable and relatively innocuous stock solutions.
Leukocyte emigration and migration in the vagina following mating in the rabbit
Authors: Phillips David M. , Mahler Susan 
Published: February 2005

AbstractWithin 45 minutes after mating in the rabbit, numerous heterophil leukocytes adhere to the endothelium of venules in the vagina. Initial association appears to occur via small protuberances from the leukocyte which fit into small indentions in the endothelial cell. Following adherence, leukocytes flatten and pass between endothelial cells. A regular intercellular space separates the leukocyte from the endothelial cells. Leukocytes subsequently migrate through the connective tissue to the epithelium. By three hours postcoitus, the region beneath the basement lamina of the vaginal epithelium is crowded with numerous juxtaposed leukocytes. Leukocytes subsequently migrate between epithelial cells into the vaginal lumen where they actively engulf spermatozoa. Spermatozoa appear to be ingested head first. Numerous small filaments are observed in the leukocyte cytoplasm in the region adjacent to the sperm head. Degranulation of azurophyl granules follows sperm uptake. The leu kocyte response can be elicited either by spermatozoa (from the epididymis) or by semen (from vasectomized bucks), but is not elicited by ovulation (with human chorionic gonadotropin). It is suggested that the response may be initiated because the vagina does not distinguish between semen, spermatozoa and bacterial infection.
Hemopoietic repopulating potential of subcutaneous exudate cells
Authors: Scuderi Philip , Rosse Cornelius , Everett Newton B. 
Published: February 2005

AbstractInflammatory exudate (SE) cells were collected from subcutaneous coverslips in mice and transferred into lethally irradiated (1,000 r) recipients. Eight days after transplantation 59Fe incorporation in the spleen and bone marrow was significantly greater than in controls treated with the suspending medium only. One hundred percent of mitoses were of the T6T6 karyotype in the marrow and spleen when SE cells were obtained from CBA/T6T6 donors. The repopulating potential of SE cells, however, lagged significantly, behind that of bone marrow cells and the failure to observe consistently macroscopic spleen colonies calls into question whether the observed regeneration was due to pluripo‐tent stem cells. Radioautographic studies with 3H‐TdR showed that the majority of SE cells had recently been generated, but long‐lived, noncycling cells of lymphoid and monocytoid morphology were also present in the exudate.
A technique for the dry preservation of functioning orthopaedic specimens
Authors: Hamilton James J. 
Published: February 2005

AbstractA method is presented by which fresh anatomical material may be preserved in a dry state while maintaining joint function and motion. This method could be likened to the tanning of the tendons and ligaments directly on the bones. Mastery of this technique has allowed the preservation of not only the tendinoskeletal system, but also the nervous, vascular, and endotracheal systems as well. While some skill in dissection is necessary, a large amount of the dissection can be done by chemical methods. The actual processing of the specimen is easily done with materials that are readily available. When finished, the specimen is dry, flexible, essentially odorless, and extremely durable. This method can be utilized for material ranging from simple osseous specimens to highly sophisticated dissections. These specimens have been found to be of exceptional advantage in teaching by demonstrating function as well as spatial relationships.
Intercellular junctional complexes of the rat seminiferous tubules: A freeze‐fracture study
Authors: McGinley Dennis , Posalaky Zoltan , Porvaznik Martin 
Published: February 2005

AbstractThis paper provides a description of the intercellular junctions in the rat testis, as observed using the freeze fracture technique. These intercellular junctions were categorized into four general types: Sertoli cell tight junctions, myoid cell tight junctions, gap junctions, and “heterogeneous junctions.” The Sertoli cell tight junctions had a mean depth of 3.1 μm in the basal to apical direction, and contained 25 to 50 (average: 36) parallel rows of particulate sealing elements. The myoid cell tight junction was neither continuous nor extensive, but focal in nature. Interestingly the sealing elements of this junction, like those of the Sertoli cell tight junction, were quite particulate in nature. Typical gap junctions were observed between Sertoli cells, where they were intercalated between the parallel rows of the Sertoli cell tight junction. The most interesting observation was the identification of gap junction‐like structures, in various stages of formation, on germ cell membrane fracture faces, both in the basal and adluminal compartments. Lastly, the unusual “heterogeneous junction” was observed on large membrane fracture faces in close proximity to cells in the adluminal compartment, presumably between Sertoli cells. These junctions appeared to consist of both tight and gap junction elements.
Seasonal variation in the morphology of thyroid parafollicular (C) cells in the woodchuck, Marmota monax: A light and electron microscopic study
Authors: Frink R. , Krupp P. P. , Young R. A. 
Published: February 2005

AbstractThe morphology of parafollicular (C) cells in the thyroid gland of the woodchuck, Marmota monax, was studied during the four seasons of the year. The spring C cells are characterized by a large Golgi zone, rough‐surfaced endoplasmic reticulum, free ribosomes and relatively few dense granules. In the summer these cells appear to be larger and many are packed with dense granules. Fall cells exhibit morphological characteristics suggestive of intense synthetic activity, having rough‐surfaced endoplasmic reticulum in whorls or parallel arrangement, a large Golgi apparatus and few, to many granules, some of which are larger than those seen in the spring and summer C cells. In the winter, most of the C cells are packed with granules. The Golgi zone, when observed, is small and the rough‐surfaced endoplasmic reticulum is sparse. Many cell profiles exhibit apparent granule dissolution. These cyclic morphological findings are discussed along with previous studies of other hibernators and are correlated with the seasonal activities of the woodchuck.