bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunoultrastructural studies of human NK cells: I. Ultracytochemistry and comparison with T cell subsets
Authors: Kang Yuan‐Hsu , Carl Mitchell , Grimley Philip M. , Serrate Susana , Yaffe Lyn
Published: February 2005

Human NK activity is known to be associated with a population of large granular lymphocytes (LGL) exhibiting several immunophenotypic surface markers including Leu‐11a (NKP‐15), Leu‐7 (HNK‐1), Leu‐3a (T4), and Leu‐2a (T8). Based upon correlation with cytolytic activity, Leu‐11a is now considered the most specific antigenic marker for human NK cells. Present investigation compared the ultrastructure of cells expressing Leu‐11a, Leu‐7, Leu‐3a, and Leu‐2a, both in human peripheral blood lymphocytes (PBL) and the purified LGL fraction. Subcellular cytochemical reactions were investigated in Leu‐7+ or Leu‐11a+ PBL or LGL and in cells conjugated with K562 targets (indicating NK cytolytic potential). The surface markers, localized with monoclonal antibodies, were detected by immunoelectron microscopy by using direct or indirect avidin‐biotin‐peroxidase (ABC) or colloidal gold methods. A peroxidase‐colloidal gold double‐labeling system was used to identify subsets of Leu‐7+ or Leu‐11a+ cells. Previously described ultrastructural features of LGL including a villous surface, reniform nuclei, low nuclear/cytoplasm ratios, and abundant cytoplasm with vesicles, vacuoles, electron‐dense granules, parallel tubular arrays (PTA), or paracrystalline inclusions were associated with Leu‐7+, Leu‐11a+, Leu‐7+/Leu‐11a+, Leu‐7+/Leu‐11a−, and Leu‐7−/Leu‐11a+ PBL or LGL. Results showed that the Leu‐7+/Leu‐11a+ cells were the most abundant NK cells in PBL. Lymphocyte subsets with Leu‐3a or Leu‐2a surface marker showed some ultrastructural features including PTA similar to Leu‐7+ cells and Leu‐11a+ cells, and their subsets. These T‐cells appeared ultrastructurally more similar to the Leu‐7+/Leu‐11a− subset.

Cytochemical studies showed that electron‐dense cytoplasmic granules and PTA typical of the Leu‐11a+ cells and Leu‐7+ cells contained glycoprotein, acid phosphatase, and arylsulfatase. Large cytoplasmic vacuoles were heterogeneous and typically contained electron‐dense material with DAB reactivity, membranous material, PTA, and/or paracrystalline inclusions. Glycoprotein, acid phosphatase, and arylsulfatase, and peroxidase reactive material were also found in these vacuoles. These features suggested that the vacuoles could be secondary lysosomes. The coexistence of intact PTA or degenerating PTA in the same vacuoles with paracrystalline inclusions suggested that the latter are possibly derived from PTA.
Comparative study of the distribution of venous values in the lower extremities of black Africans and Caucasians: Pathogenetic correlates of prevalence of primary varicose veins in the two races
Authors: Banjo Adesegun O.
Published: February 2005

The incidence of valves in the major veins of the lower extremities of Africans and Caucasians was studied. Valves are absent in the inferior vena cava in both races. In the common iliac veins, 1–7% of Caucasians and 1% of Africans have rudimentary valves.

Normal valves exist in the following veins: the external iliac veins—22–33% of Caucasians and 9% of Africans; the femoral vein segment above the saphenofemoral junction—67–81% of Caucasians and 93% of Africans; the 3‐cm‐length of the femoral vein below the profundofemoral junction—90% of Caucasians and 100% of Africans; the terminal 3 cm of the great saphenous vein—100% Caucasians and 98% Africans.

The lower incidence in the number of valves in Caucasians may account for the high prevalence (10–18%) of varicose veins in Caucasians; the reverse of this relationship is suggested for the low prevalence (1–2%) of the condition in Africans. Factors influencing the development of incompetent valves are discussed.
Skeletal changes in the hindlimbs of bipedal rats
Authors: Kay Elizabeth D. , Condon Keith
Published: February 2005

Experimental bipedalism in rats has been proposed as a model for studying evolutionary and orthopedic change. This study quantified the skeletal changes which occur in the hindlimbs of these bipedal rats. Bipedalism was produced in 16 male rats by forelimb amputation during the neonatal period. The rats were sacrificed at maturity and the femurs and tibia‐fibulas from randomly selected hindlimbs were weighed and measured. Out of a total of 25 parameters, only one, anteroposterior diameter of the proximal femur, was found to differ statistically between the bipedal and control groups. No changes were found in bone length, weight, or curvature. The results of other bipedal studies were reviewed, in light of these findings; and it is concluded that rats do not achieve true bipedalism, or increased hindlimb loading.
3H‐mannose utilization by fibroblasts of the periodontal ligament
Authors: Cho Moon‐Il , Garant Philias R.
Published: February 2005

The synthesis, intracellular translocation, and secretion of mannose‐containing glycoproteins(s) by periodontal ligament fibroblasts have been investigated by means of electron microscopic radioautography. Tritiated mannose was administered to young mice via jugular vein, and radioautographs were prepared at 5, 10, 20, and 35 minutes, 4 and 8 hours after injection. Analysis of electron microscopic radioautographs revealed a maximum labeling (94%) with 3H‐mannose of the rough endoplasmic reticulum at 5 minutes. Labeling of the Golgi components started to increase from 10 minutes (14%) and reached a maximum level at 20 minutes (31.2%). At 35 minutes, secretion granules, dense bodies, profiles of intracellular collagen, and the cell surface were labeled. At 8 hours, most labelling (79.2%) was extracellular, and associated either with the collagenous matrix (43.7%) or the cell surface (35.5%). Cytoplasmic vesicles containing dense materials around collagen fibrils were also labeled at 8 hours. It is concluded that mannose is directly incorporated into the rough endoplasmic reticulum (RER), and that mannose‐containing glycoprotein(s) are packaged in the Golgi apparatus into secretory granules. Mannose‐containing glycoproteins(s) become distributed on the periodontal ligament (PDL) fibroblast cell surface, cytoplasmic dense bodies, and the extracellular matrix.
Healing of experimentally produced lesions in articular cartilage following chondrocyte transplantation
Authors: Grande Daniel A. , Singh Inder J. , Pugh James
Published: February 2005

Articular cartilage is known to have limited ability to heal once injured, and attempts to heal lesions in cartilage have yielded equivocal results. The following experiments were performed to investigate healing in cartilage following transplantation of chondrocytes grown in vitro. The knee joint of the New Zealand White rabbit was used as the experimental model. An initial baseline study was made to determine the intrinsic capability of cartilage for healing defects that do not fracture the subchondral plate. A second experiment examined the effects of autologous in vitro grown chondrocytes on the healing rates of these defects. The results were evaluated by qualitative and quantitative light microscopy.

In control defects not grafted with chondrocytes, 6 weeks after the initial defect was created, there was little repair. Macroscopic and histological findings were consistent with an osteoarthritic pathology such as synovitis and “cell nests.”

Macroscopic results from grafted specimens displayed a marked decrease in synovitis and other degenerative changes. Defects which had received transplants had a significant amount of cartilage reconstituted (82%) compared to ungrafted controls (18%). Controls showed a healing rate comparable to that obtained in the initial baseline study.
Incorporation of strontium into the calcium carbonate crystals of the endolymphatic sac in the tree frog (Hyla arborea japonica)
Authors: Kawamata Seiichi
Published: February 2005

Tree frogs were loaded with strontium chloride (SrCl2). The incorporation of strontium metal into the calcium carbonate (CaCO3) crystals located both in the inner ear and in the endolymphatic sac was studied by x‐ray microanalysis (XMA) and scanning electron microscopy (SEM). In the inner ear, strontium was not recognized except for traces in a few crystals. When observed by SEM, these crystals had a faceted body and two pointed ends with rather smooth surfaces. However, in the endolymphatic sac, which greatly expands into the spinal canal, strontium was clearly present at every surface of all crystals. Careful examinations by point and line XMA revealed that strontium x‐ray counts were highest at the pointed ends and decreased sharply and then gradually toward the equator of the crystals. SEM observations revealed that the crystals in the endolymphatic sac always had rough and irregular surfaces regardless of their shapes and sizes. Calcium was always found in crystals of both organs. Except for calcium and strontium, other elements including sodium and heavier elements were negligible in XMA. These findings suggest that strontium is incorporated into the crystals only in the endolymphatic sac, and the rough‐surfaced covering of these crystals reflects newly deposited strontium salt. It seems to indicate that these crystals grow predominantly by accretion.
Stereological analysis of the muscle‐tendon junction in the aging mouse
Authors: Trotter J. A. , Samora A. , Hsi K. , Wofsy C.
Published: February 2005

Transmission of contractile tension from skeletal muscle fibers to connective tissue elements is thought to occur at the muscle‐tendon junctions, specialized regions at the extreme ends of the fibers. Previous stereological studies on adult mouse and chicken fibers have shown that, with reference to equal cross‐sectional areas of myofibrils, the muscle‐tendon junctions of faster fibers have significantly more surface membrane devoted to force transmission than do those of slower fibers (Trotter et al.: Anat. Rec. 213:16–25, 1985a; Trotter et al.: Anat. Rec. 213:26–32, 1985b; Trotter and Baca: Anat. Rec. 218:256–266, 1987). In the present study we have analyzed the muscle‐tendon junctions of 30‐month‐old mice, employing techniques for scanning and transmission electron microscopy and for ultrastructural stereology which are identical to those previously used to study the same muscles in 4‐month‐old mice. Whereas the principal structural features of the muscle‐tendon junctions of fibers from adult and aged mice are indistinguishable, stereological analyses of the fiber‐tendon interfaces indicate that, in aging animals, the interfacial ratio (the ratio of the surface area of force‐transmitting membrane to the cross‐sectional area of force‐generating myofibrils) is significantly reduced. While the interfacial ratio of fast‐twitch fibers of the adult plantaris is about 14.5, the corresponding ratio in aged animals is about ten. In the predominantly slow‐twitch fibers of the adult soleus, the interfacial ratio is about ten at the insertion and about 12.7 at the origin, whereas the corresponding ratios in the aged animals are both about ten. These findings are consistent with the notion that the amount of surface area specialized for force transmission is related to the contractile speed of the fiber.
Differential effects of tissue processing on human embryonic and fetal skin
Authors: Foster Carolyn A.
Published: February 2005

To most accurately evaluate quantitative data from studies of developing epidermis, the effects of tissue processing on human embryonic and fetal skin (8–20 weeks gestational age) were examined using two different techniques: 1) EDTA‐separated epidermal sheets that were briefly fixed in 2% paraformaldehyde, processed through Permount infiltration, and prepared as whole mounts on glass slides, and 2) skin that was fixed in Karnovsky's fixative and embedded in Epon. Based on en face measurements of surface area before and after tissue processing, both procedures caused differential, age‐dependent shrinkage. However, the trend of increasing shrinkage was inversely related to increasing age in the paraformal‐dehyde‐fixed epidermal sheets (y = 57.14 + 1.26x, where x = gestational age in weeks and y = % of original surface area), but directly correlated with aging in the Karnovsky‐fixed skin (y = 955.62 − 232.77x + 20.38x2). Shrinkage of epidermal sheets occurred during the dehydration and clearing steps, whereas most of the dimensional changes in whole skin took place during fixation in Karnovsky's. These differences are probably due to greater cross‐linking of proteins and longer fixation time in the more concentrated and fast‐acting Karnovsky's as well as the influence of increasing quantities of fibrous proteins in the dermis of whole skin.
Analysis of crystallite shape in rat incisor enamel
Authors: Warshawsky H. , Bai P. , Nanci A.
Published: February 2005

The hydroxyapatite crystallites of mammalian enamel appear as hexagons when seen in cross‐sections examined with the transmission electron microscope. Using goniometric transmission electron microscopy, stereo‐pair electron micrographs and freeze‐fracture replicas, two models have been proposed to explain the hexagonal crystallite profile. The “hexagonal ribbon” model proposes that hexagonal profiles are true cross‐sections of elongated hexagonal ribbons. The “rectangular ribbon” model proposes that crystallite profiles are three‐dimensional rectangular segments (parallelepipeds), which are contained in the Epon sections and project as opaque hexagons in routine transmission electron micrographs. Morphological observations together with predictions from models indicate that the crystallites in rat incisor enamel are flat ribbons with rectangular cross‐sectional profiles. The hexagonal images seen in electron micrographs of thin sections of enamel result from viewing parallelepiped‐shaped segments of these crystallites as two‐dimensional shadows.
Effects of orthodontic forces on the morphology and diameter of sharpey fibers of the alveolar bone of the rat
Authors: Martinez R. H. , Johnson R. B.
Published: February 2005

There is little information available concerning the effects of functional and therapeutic forces on Sharpey fibers and adjacent bone matrix. In the present study, springs were placed between the left first and second maxillary molar teeth of rats and retained for 1, 2, 3, 4, or 5 days. The right side served as a control. Tissues from sham‐operated, untreated animals were also studied. Maxillae were removed, fractured, rendered anorganic with sodium hypochlorite, and then examined by scanning electron microscopy (SEM). Some tissues were demineralized and examined by high‐voltage electron microscopy (HVEM). Sharpey fibers were studied at the alveolar wall and at the midline of the interdental septum (intra‐septal Sharpey fibers). In 5‐day experimental tissues, SEM showed intra‐septal Sharpey fibers had either a reduced number of, or lacked, unmineralized cores. Unit collagen fibrils in 5‐day tissues viewed by HVEM were densely packed into Sharpey fibers which had no afibrillar areas. Sharpey fibers at the alveolar wall demonstrated no observable changes in morphology or in pattern of mineralization. After 5 days of spring placement, the mean diameters of intra‐septal fibers were significantly less than those at the alveolar wall (p < 0.001). The disparity in Sharpey fiber diameters of treated and untreated control animals suggests that untreated controls are essential to the design of studies of rodent tooth movement. This study suggests that orthodontic tooth movement produces changes in the morphology and mineralization patterns of Sharpey fibers which might affect the mechanical strength of the periodontium.
Cyclic localization of actin and its relationship to junctional complexes in maturation ameloblasts of the rat incisor
Authors: Nishikawa Sumio , Josephsen Kaj
Published: February 2005

The patterns of fluorescence associated with maturation ameloblasts of mandibular incisors labeled with 7‐nitrobenz‐2‐oxa‐1,3‐diazole‐phallacidin (NBD‐phallacidin) for the detection of F‐actin were investigated in normal and fluoride‐treated rats. In normal rats, bands of smooth‐ended ameloblasts (SA) exhibited intense fluorescence at their proximal ends only. Bands of ruffle‐ended ameloblasts (RA) exhibited strong fluorescence at their distal ends as well as at their proximal ends. Regional differences in degree of intensity within the bands and between bands were displayed. In the apical part of the RA bands the proximal fluorescence was intense; it then decreased in an incisal direction; and it finally was absent close to the adjacent SA band. The incisal extension of strong proximal fluorescence in RA bands was short in early maturation and long in late maturation. The fluorescence pattern at both ends of the ameloblasts was cyclically repeated throughout the region of ameloblast modulation corresponding to the numbers of SA bands. In rats receiving 113 ppm fluoride in their drinking water for 2 months the number of fluorescence and ameloblast modulation cycles was reduced equally indicating that the cyclic F‐actin localization is a phenomenon related to ameloblast modulation. Electron microscopy revealed that areas of strong fluorescence contained filament bundles, presumably actin filaments, in relation to continuous junctions occluding the interameloblast spaces. Areas of weak or no fluorescence were related to discontinuous macular junctions. The results suggest that the changes in F‐actin distribution correlate well with junctional complex development, and therefore, possible functions related to the interameloblast spaces within the RA bands may be redistributed as the ameloblasts are carried incisally by the erupting incisor.
Comparison of regional differences in cardiac myocyte dimensions in rats, hamsters, and guinea pigs
Authors: Campbell Scott E. , Gerdes A. Martin , Smith Teri D.
Published: February 2005

Isolated myocytes were prepared from Sprague Dawley rats, golden Syrian hamsters, and Hartley guinea pigs to investigate regional variations in myocyte size. Cell volume (V) was measured with a Coulter Channelyzer, cell length (L) was measured directly, and cross‐sectional area (CSA) was calculated from V/L. Compared to values from the left ventricle (LV), right ventricular L was shorter in the rat (P < .01) and hamster (P < .05) and longer in the guinea pig (P < .01). Guinea pig atrial L was shorter (P < .01) than L in the right ventricle (RV) but did not differ from L in the LV. No significant differences in L existed between endomyocardium, middle myocardium, and epimyocardium of the LV in all three species. In rats and hamsters, myocytes from the RV had smaller V and CSA values (P < .01) compared to any region of the LV. A transmural gradient of cellular dimensions existed in the LV of the rat, but not in hamster, with V and CSA of endomyocardium being largest and epimyocardium smallest (P < .01). Endomyocardial V and CSA were larger (P < .01) than all other regions in the hamster, but the difference was not significant compared to epimyocardial V. In the guinea pig, no significant differences in V existed between RV and LV or between the three LV regions. No pattern of regional differences was seen between ventricular CSA values in the guinea pig. Guinea pig atrial V and CSA values were smaller (P < .01) than those for ventricular myocytes. Therefore, regional differences in cardiac myocyte size vary among different rodent species.
Development of ciliated cells in the human fetal oviduct: An ultrastructural study
Authors: Konishi Ikuo , Fujii Shingo , Parmley Tim H. , Mori Takahide
Published: February 2005

Prenatal development of ciliated cells in the human fallopian tube was studied by light and electron microscopy in specimens obtained from 12 fetuses, aged 12–40 weeks. On light microscopy, transverse sections of the ampullary portion of the tube revealed a slit‐like lumen at 12 weeks. The lumen began to fold by 15 weeks, and formed the typical villous structures by 31 weeks. On electron microscopy, the epithelial cells contained a large number of sub‐ and supranuclear glycogen particles until 18 weeks and an occasional solitary cilium. At 20–22 weeks, instead of glycogen particles, cytoplasmic organelles such as mitochondria, rough endoplasmic reticula and Golgi apparatus were well developed, and some cells possessed cilia with a 9 + 2 microtubular structure. Between 22 and 31 weeks, ciliated cells were sporadically observed. At 31 weeks, the epithelial cells accumulated a large number of sub‐ and supranuclear glycogen particles. Afterwards, numerous ciliated cells with well‐developed cytoplasmic organelles were observed by 40 weeks.
Localization of calbindin‐D28K in calcitonin containing cells of chick ultimobranchial glands
Authors: Taylor Alan N. , Inpanbutr Nongnuch , Deftos Leonard J.
Published: February 2005

Specific antisera raised against calbindin‐D28K (CaBP), the vitamin D‐dependent calcium‐binding protein from chick intestine, was used to localize the protein in chick ultimobranchial glands (UB glands) by the peroxidase‐antiperoxi‐dase technique. CaBP was localized in secretory cells in the cell cords and in a few cells of the epithelium lining the follicles. It was not found in the fibroblastlike cells in the cell cords nor in islands of parathyroid tissue present in the UB gland. The immunomarker for CaBP was distributed throughout the cytoplasm and nucleus of the secretory cells. The same cells demonstrated a positive reaction in their cytoplasm when reacted with an antiserum specific for salmon calcitonin (CT), thus confirming the presence of CaBP and CT in the same UB‐gland secretory cells. In other tissues, the presence of CaBP is regarded as an end‐organ marker for actions of the vitamin D endocrine system. This novel demonstration of CaBP in UB‐gland cells responsible for secretion of calcitonin suggests a direct effect of the vitamin D endocrine system on those cells in addition to an indirect effect through the stimulation produced by elevated circulating calcium levels.
Behavior of chick primordial germ cells moving toward gonadal primordium in vitro: Scanning electron microscopic study
Authors: Kuwana Takashi , Miyayama Yukihiko , Kajiwara Yuji , Fujimoto Toyoaki
Published: February 2005

Primordial germ cells (PGCs) from embryonic chick blood were cultured in vitro and the cells being attracted by the gonadal primordium (germinal ridge; GR) were studied by scanning electron microscopy (SEM). Immediately after confirming PGC locomotion by 16‐mm time‐lapse filming or time‐lapse video recorder under the microscope, PGCs in various phases of locomotion were prepared for SEM, and their locomotion was analyzed.

With the thin collagen layer as a substrate, the sequence of the PGC locomotion was as follows: (1) The PGC produced a small pseudopodium. (2) This pseudopodium enlarged to the GR, and PGC‐substrate contact was consolidated around the periphery of the pseudopodium, while the body of PGC remained detached from the substrate. (3) Finally, the PGC as a whole moved toward the GR, being trailed by the process.

The locomotion of the PGC on the thick collagen layer as a three‐dimensional substrate was as follows: (1) The PGC protruded a pseudopodium in the direction of the GR. (2) This pseudopodium elongated through the collagen network. (3) The tip of the pseudopodium swelled and the main body of the PGC flowed into the swelling portion, leaving a slender cytoplasmic tail. (4) The tail was finally incorporated into the leading part of the cell. This behavior of the PGC seemed to reflect the features of interstitial PGC in vivo.
Morphologic stages of the terminal hypertrophic chondrocyte of growth plate cartilage
Authors: Farnum Cornelia E. , Wilsman Norman J.
Published: February 2005

Recent biochemical and morphologic evidence supports the concept that hypertrophic chondrocytes of growth plate cartilage are fully viable cells that play a major functional role in controlling endochondral ossification. However, events associated with chondrocyte death remain unknown. In this study we assess the viability of terminal hypertrophic chondrocytes in situ in an organ culture system viewed simultaneously with rectified Nomarski interference contrast optics and with vital staining under fluorescence optics. Second, we use two methods of optimal chemical fixation at the ultrastructural level to define morphologically distinct stages of the terminal hypertrophic chondrocyte, which we interpret as the stages preceding chondrocyte death. An analysis of serial sections at the light microscope level showed that terminal chondrocytes were found, with different probabilities, in three morphologically distinguishable stages. Seventy‐five percent of all profiles were fully hydrated cells with an intact plasma membrane making direct contact with the pericellular matrix, a morphology identical to that of living terminal chondrocytes viewed in Nomarski optics. Approximately 1% of terminal chondrocytes, while still in a fully hydrated state, consistently made a direct asymmetrical contact of the plasma membrane with the last transverse septum. In 24% of the profiles, terminal chondrocytes were found as condensed cells that retained their attachment to the last transverse septum. The stages were not characteristic of chondrocytes positioned more proximally in the growth plate. We hypothesize that a condensed morphology eventually characterizes each hypertrophic chondrocyte, and we relate these observations to current hypotheses concerning the mechanism of death of hypertrophic chondrocytes.
Paravascular cells in endosteal spaces of alveolar bone contribute to periodontal ligament cell populations
Authors: McCulloch C. A. G. , Nemeth E. , Lowenberg B. , Melcher A. H.
Published: February 2005

Enddosteal spaces of alveolar bone communicate with the periodontal ligament and may contribute to its cell populations. We examined cell proliferation and migration in endosteal spaces and in the periodontal ligament contiguous with these spaces. Radioautographs of mouse mandibular molar were prepared from animals pulse‐injected with 3H‐Tdr and sacrificed in groups of 22 mice each at 1 h, 1, 3, and 7 d after labeling. Cell counts, labeling indices, grain counts, and progenitor cell ratios were determined. The data indicate that endosteal spaces are enriched with 3H‐Tdr‐labeled progenitor cells whose progeny rapidly migrate out of the compartment. The periodontal ligament contiguous with the endosteal spaces exhibited 5 times as many labeled cells as other sites in this tissue. Thickened areas of cementum were coincident with the openings of endosteal spaces in over 64% of observations. The data are consistent with the hypothesis that cells migrate from endosteal spaces into the periodontal ligament and there express the phenotype for osteoblasts or cementoblasts.
Embryonic development of the freshwater crayfish (Pacifastacus leniusculus Dana): A scanning electron microscopic study
Authors: Celada Jesús D. , de Paz Paulino , Gaudioso Vicente R. , Fernández Ramón
Published: February 2005

The egg development of the freshwater crayfish (Pacifastacus leniusculus Dana) under laboratory conditions is studied in this work from spawning to hatching. The sequence of its development is presented here, and the chronology of the different embryonic phases is established at one specific temperature (15.5°± 1°C).
The number of neurons in dorsal root ganglia L4–L6 of the rat
Authors: Schmalbruch Henning
Published: February 2005

The number of neurons in the dorsal root ganglia L4–L6 of the rat was determined because published data are inconsistent and in general incompatible with the number of afferent axons in the sciatic nerve. Nucleoli were counted in serial sections; epoxy‐resin sections 3 μm thick, or paraffin sections 5 μm thick, or unstained 12‐μm paraffin sections of osmicated tissue were used. Correction factors for split and multiple nucleoli were obtained by counting nucleolar profiles in consecutive sections of identified cells. Dividing the number of nucleolar profiles into the number of cells gave the factor by which the counts of nucleolar profiles had to be multiplied to obtain the number of neurons.

The ganglia L4, L5, and L6 contained about 12,000, 15,000 and 14,000 neurons, respectively, when resin sections were used. The standard deviation for the average of 41,000 neurons in the three ganglia was 8% of the mean value. The results compare well with the number of dorsal root fibers, and with the fact that the sciatic nerve at midthigh, to which less than half of the neurons connect, contains 19,000 afferent axons. The data obtained from the paraffin series were 23% smaller, but still considerably higher and less variable than all previously reported data. The main problem with stained paraffin sections was that most small neurons had multiple nucleoli attached to the membrane of the nuclei, which only measured 10 μm in diameter. The nucleoli often projected into the dark cytoplasm and were difficult to identify.
Resident sinusoidal macrophages in the liver of the brown bullhead (Ictalurus nebulosus): An ultrastructural, functional and cytochemical study
Authors: Hampton James A. , Klaunig James E. , Goldblatt Peter J.
Published: February 2005

Ultrastructural, functional, and cytochemical characteristics of resident sinusoidal macrophages (RSM) in brown bullhead (Ictalurus nebulosus) liver were examined. Following perfusion fixation of the hepatic vascular bed, light micrographs revealed RSM that possessed multiple elongate cytoplasmic processes and frequently contained erythrocytes in various stages of degradation. Following brief perfusion fixation, light microscope examination of vibratome sections of bullhead liver reacted for peroxidase revealed intensely positive RSM. By transmission electron microscopy, peroxidase activity was localized to the nuclear envelope and cytoplasmic granules of RSM and in endothelial and perisinusoidal fat‐storing cells. In cryostat sections of fresh‐frozen liver, glucose‐6‐phosphate dehydrogenase (G‐6‐PDH) was uniformly distributed over hepatocytes, whereas intensely positive punctate staining for G‐6‐PDH was localized over RSM. To test for phagocytosis by RSM, latex beads (0.81 μ) were injected into a tributary of the hepatic portal vein 2 min prior to perfusion fixation. Latex beads appeared either singly or in dense aggregates within RSM. Ultrastructurally, RSM were characterized by an irregularly shaped, eccentrically located nucleus, electron‐dense vacuoles, small patches of granular endoplasmic reticulum, a well‐developed Golgi apparatus, elongated mitochondria, desmosomes or desmosome‐like densities that served as a source of attachment to endothelial cells, and a centriole with radiating microtubules. Invaginations of the plasma membrane (vermiform processes) characteristic of mammalian Kupffer cells were not observed in bullhead RSM. The results indicated a resident cell population of sinusoidal macrophages in the bullhead liver with properties that protially resembled mammalian Kupffer cells. These results are important for the identification of the normal resident cells in the bullhead liver.
Two types of secretory granules in gonadotrophs: Discrimination by the simultaneous EM immunocytochemical localization of serotonin and β‐follicle stimulating hormone
Authors: Payette Robert F. , Gershon Michael D. , Nunez Eladio A.
Published: February 2005

The hypothesis that the secretory granules of mammalian gonadotrophs are heterogeneous was tested. Previous studies had shown that all of the granules contain β‐luteinizing hormone (β‐LH) immunoreactivity, and some contain β‐follicle stimulating hormone (β‐FSH) or 5‐HT immunoreactivity. Moreover, differential release of β‐LH and β‐FSH has also been demonstrated. In the current study the pituitary glands of mice were investigated immunocytochemically at the ultrastructural level with antisera directed against human growth hormone (GH), β‐LH, β‐FSH, and 5‐HT. The immunoreactivities of β‐LH, β‐FSH, and 5‐HT were restricted to gonadotrophs. No 5‐HT immunoreactivity was seen in somatotrophs, identified by the immunoreactivity of GH in the secretory granules of these cells. Antisera to β‐LH labeled all gonadotroph granules; however, anti‐β‐FSH and anti‐5‐HT sera labeled only subsets of the granules. The proportion of granules labeled could not be increased by doubling the concentration of anti‐β‐FSH serum. The incidence of double labeling of granules by antisera to β‐FSH and 5‐HT was significantly less than that predicted from the incidence of granule labeling by either reagent alone. It is concluded that β‐FSH and 5‐HT immunoreactivities do not co‐exist in the same secretory granules of gonadotrophs; therefore, these granules are heterogeneous and there must be at least two types of granules. It is possible that the two types of granules may be responsive to different second messengers, thereby explaining the differential release of LH and FSH.
Neuromuscular junctions in adult and developing fast and slow muscles
Authors: Kwong W. H. , Gauthier Geraldine F.
Published: February 2005

Functional changes that occur just before hatching in future fast muscles of the chicken are thought to be influenced by the pattern of innervation. We have compared the neuromuscular junctions of two fast muscles, the posterior latissimus dors (PLD) and the pectoralis, which differ in their myosi composition at 18 days in ovo. We have also presented new information on the neuromuscular junctions of the adult fast muscles and an adult slow muscle, the anterior latissimus dorsi (ALD). Both categories of adult muscles were heterogeneous, and there was little difference between endplates of the two fast muscles or between the fast and slow muscles. In contrast, there were significant structural differences between the two fast muscles during embryonic development. In early embryonic muscle fibers, which synthesize embryonic forms of myosin, individual motor endplates were contacted by multiple axon terminals. At 18 days in ovo, the majority of the neuromuscular junctions in the pectoralis continued to be multiterminal, whereas all but one of the terminals had been withdrawn from each endplate in the PLD. This single terminal had a unique form that distinguished it from the embryonic pectoralis and also from the two adult muscles. By 7 days after hatching, the neuromuscular junctions of both muscles had single terminals. They were different from the embryonic terminals, through not necessarily equivalent to adult terminals. The results show that multiple terminals persist at 18 days in ovo in the muscle that continues to express an embryonic myosin, but they have been withdrawn from the muscle that has lost this myosin. It is concluded, from combined data on the two muscles, that maturation of the neuromuscular junction during embryonic and late posthatch development is correlated with transitions in the myosin pattern and in contractile properties.
Topography and behavior of Sertoli cells in sparse culture during the transitional remodeling phase
Authors: Tund Pierre S. , Choi Anthony H. C. , Fritz Irving B.
Published: February 2005

We report observations on the behavior of Sertoli cells in sparse culture during the period from the time of plating to the time of initial confluence (the transitional remodeling phase). Changes in shape, structure, and polarity of cells, as well as changes in migration patterns and cell‐cell association patterns, have been followed during the transitional remodeling phase with the aid of topographical markers. These markers are based upon differences between ultrastructural features of the basolateral and apicolateral surfaces. The basolateral surface is characterized by plasmalemmal blebs, whereas the apicolateral surface is characterized by filopodial extensions. Structural differences observed in sity remain evident in Sertoli cells isolated by sequential enzymatic treatments that are described. Another marker is provided by laminin‐binding sites, which are detected exclusively on the blebbed, basolateral surfaces of freshly prepared Sertoli cell aggregates. The orientation described is sustained during the initial radial migration of Sertoli cells explanted on uncoated glass coverslips. Under these conditions, blebs are detected only on the dorsal surfaces, and filopodial extensions are evident only on the ventral surfaces. In contrast, Sertoli cells sparsely plated on a reconstituted basement membrane (air‐dried Matrigel) migrate rapidly, display an extraordinary capacity to form elaborate cytoplasmic extensions for cell‐cell and cell‐substratum contracts, and readily retract blebs and filopodial extensions. These cells do not form mosaic borders, whereas cells plated on uncoated glass do form a monolayer with mosaic‐like borders. Cells sparsely seeded on gelated Matrigel migrate preferentially at gaps between adjacent cell explants, and develop a compact cell‐cell association pattern. These cells display few, if any, cytoplasmic extensions. We compare the behavior of Sertoli cells sparsely plated on Matrigel with the behavior of Sertoli cells in situ during different stages of development.
Dynamic changes in Sertoli cell processes invading spermatid cytoplasm during mouse spermiogenesis
Authors: Sakai Yasuhiro , Nakamoto Tadashi , Yamashina Shohei
Published: February 2005

Studies using thick sections stained by ATPase cytochemistry and scanning electron microscopy were carried out to determine three‐dimensional ultrastructural alterations in Sertoli cell processes invading neighboring spermatids during mouse spermiogenesis. Sertoli cell processes start invading spermatid cytoplasm at the acrosomal phase of development and undergo considerable change at the maturation phase of development. At step 14, these processes elongate and begin to branch in the spermatid cytoplasm, and by step 15, they extend in various directions to form a complex of canals that the authors have designated the canal complex.

The present observations also clarify that the complicated canal complex undergoes regional modification. At the late stages of maturation, the endoplasmic reticulum had gathered with other cell organelles to form aggregates of endoplasmic reticulum in the vicinity of which invading Sertoli cell processes extensively ramify further into thin tubules that intertwine with each other to form a region of thin tubules. In thin sections, each such region was a complex, consisting of small vesicles and endoplasmic reticulum, and corresponded to what has been defined as a mixed body by Morales and Clermont (Anat. Rec., 203:233–244, 1982). During the course of the formation of the region, the invading Sertoli cell processes are continuous at all times with the cell body of the surrounding Sertoli cell.
Basal lamina fenestrations in the human colon: Transmission and scanning electron microscope study
Authors: Warfel K. A. , Hull Meredith T.
Published: February 2005

Basal lamina at the interface between colonic epithelial cells and the lamina propria was exposed by incubating colonic specimens in 1% boric acid solutions. Examination of this epithelial‐stromal interface by scanning electron microscopy (SEM) showed a smooth, slightly undulating basal lamina covering crypts and luminal surfaces. The basal lamina on the luminal surfaces had numerous round or ovoid fenestrations, most measuring 2.5–4.0 μm. These were continuous with channels in the collagen fiber network of the lamina propria. Except very near the surface, no fenestrations were found in the basal lamina lining the crypts. Transmission electron microscopy (TEM) of serial thin sections of colonic mucosa without the epithelial cells removed showed only a few actual basal lamina fenestrations. Rarely, epithelial cell processes extended into the lamina propria through the basal lamina. Most of the fenestrations seen by SEM appeared to correspond spatially by TEM to foci of close contact between the basal lamina and underlying fibroblastic cell processes. At these sites the basal lamina and fibroblastic cell process might be removed along with the overlying epithelial cells during processing with boric acid. These data support functional differences in epithelial‐stromal interaction between cell populations lining the luminal surface and those making up the crypt lining and pericryptal fibroblast sheath. The TEM findings demonstrate that the human colonic basal lamina is not absolutely continuous and that the development of basal lamina fenestrations and epithelial cell processes extending into the lamina propria is not pathognomonic of neoplastic transformation and stromal invasion.
Human lumbar zygapophyseal joint inferior recess synovial folds: A light microscope examination
Authors: Giles Lynton G. F.
Published: February 2005

The structure of human lumbar zygapophyseal joint inferior recess synovial folds as seen by high‐power light microscopy is described. Small paravascular nerves and nerves unrelated to blood vessels are demonstrated in the synovial folds. Elastic fibres are demonstrated in the interlocular fibrous septa of the synovial tissue.
Striped structures on the cytoplasmic surface membranes of the endothelial vesicles of the rat aorta revealed by quick‐freeze, deep‐etching replicas
Authors: Izumi Toshihiro , Shibata Yosaburo , Yamamoto Torao
Published: February 2005

The cytoplasmic surface of plasmalemmal vesicles in aortic endothelial cells was examined in quick‐freeze, deep‐etching replicas. In addition to the clathrin‐coated vesicles, striped patterns were observed over the cytoplasmic surface membranes of small vesicles (60–80 nm in diameter) in the unfixed specimens. These patterns were more clearly visible in saponin‐extracted specimens; the stripes were composed of several ridges or strands of 6–10 nm in width, and some were crossed. These were distinct from the characteristic pentagons or hexagons of the clathrin‐coated vesicles. This striped structure was enhanced by treatment with myosin subfragment‐1 or phalloidin, thereby indicating a possible relation to actin filaments. Patchy plaques with similar striped patterns appeared on the cytoplasmic surface of the plasmalemma proper and also on the cytoplasmic vacuole membranes together with clathrin. These striped structures may be involved in the formation and transport of so‐called “uncoated” vesicles.
Glial fibrillary acidic protein in chondrocytes of elastic cartilage in the human epiglottis: An immunohistochemical study with polyvalent and monoclonal antibodies
Authors: Kepes John J. , Perentes Elias
Published: February 2005

Glial fibrillary acidic protein (GFAP), an intermediate filament, was first discovered in the cytoplasm of reactive astroglia and to this date is regarded as a rather characteristic component of both non‐neoplastic and neoplastic astrocytes. It has, however, been found in other glial elements also, as well as in a few types of tissues outside the central nervous system. Chondrocytes in hyaline and fibrocartilage do not express GFAP, but in the elastic cartilage of the human epiglottis we found GFAP to be regularly present when tested with either polyclonal or monoclonal antibodies. While most types of cartilage in humans are believed to be of mesenchymal origin, embryologic relationship between epiglottal cartilage and the neural crest may play a role in the curious phenomenon of the regular presence of GFAP in the chondrocytes of the epiglottis.
Characterization of proximal colonic lymphoid tissue in the mouse
Authors: Perry Greg A. , Sharp J. Graham
Published: February 2005

Here were describe a nodule of lymphoid tissue which was consistently located in the proximal colon of mice approximately 25% of the distance from the cecum to the rectum. Immunohistochemical characterization of this nodule demonstrated that the majority of lymphocytes were relatively immature 14.8+ (B220+), IgM+, Ia+ (specificity 20) B cells some of which were also Ly‐1+. These nodules also possessed an occasional T cell (Thy‐1+, Ly‐1+, Lyt‐2+) aggregate at the periphery. Rare, small areas did not stain for either T or B cell markers. These lymphoid nodules were associated with epithelial cells which stained positively with the ER‐TR4 monoclonal antibody (which also recognizes thymic cortical epithelial cells) and also with ER‐TR6, which has been reported to recognize thymic macrophages or dendritic cells. The overlying colonic epithelium stained intensely with the ER‐TR4 monoclonal antibody. Proximal colonic lymphoid tissue was extremely sensitive to steroid treatment, losing approximately 80% of its mass within 24 hours in response to a single intraperitoneal injection of 2 mg hydrocortisone acetate. This response was similar to that of the thymus and to that reported for the bursa of Fabricius, but unlike that of other gastrointestinal lymphoid aggregates. These results indicated that proximal colonic lymphoid tissue contains a high frequency of relatively immature B cells and may be a primary site of their generation, possibly including some of the Ly‐1+ phenotype. These observations correlate with new evidence suggesting that the allantois participates in the formation of the distal midgut, including its lymphoid components.
Autoradiographic localization of [3H]‐thymidine incorporation in developing human esophagus
Authors: Arsenault Pierre , Menard Daniel
Published: February 2005

Cell proliferation in the developing human esophagus was investigated by by autoradiography using organ culture. The sites of [3H]‐thymidine uptake were localized in the epithelium, the mesenchyme, and the muscularis externa of fetal esophageal explants from 10 to 16 weeks of gestation. Proliferating cells were abundant throughout the stratified epithelium at 10 weeks of gestation. Many labeled nuclei in the mesenchyme and the muscular layer were observed. With the development of the stratified columnar ciliated epithelium, a confinement of the proliferating zone in the basal cell layers occurred, and ciliated cells never appeared labeled. The quantitation of proliferating cells showed a labeling index at its highest value between 10 and 12 weeks; this drastically decreased between 12 and 14 weeks' gestation. A similar pattern was noted for the mesenchyme, while the labeling index in the muscularis externa peaked during the 11–14 weeks period. In all fetuses, the highest labeling index was always recorded in the epithelium. The biochemical quantitation of the [3H]‐thymidine uptake into the total esophageal DNA clearly supported the continuous decrease of the cell proliferation determined by autoradiography between 10 and 16 weeks of gestation. The present investigation provides for the first time basic quantitative data regarding cell proliferation during a particular developmental phase of the human esophagus.
Human intervertebral disc: Structure and function
Authors: Humzah M. D. , Soames R. W.
Published: February 2005

This review begins with a brief introduction in which the development, blood supply and innervation of the intervertebral disc is considered, particularly as these may influence the following sections on structure and function. The three regions within the disc—that is, the nucleus pulposus, annulus fibrosus, and cartilage end plates—are considered in some detail. There appears to be no distinct border between the central nucleus pulposus and the outer annulus fibrosus, the main difference being in their fibrous structure. The fluid space is important in the nutrition of the disc, showing plastic deformation and recovery characteristics. The structural elements, both macroscopically and microscopically, together with the biochemical elements, are intimately related to function.

The intervertebral disc should not be thought of as a homogeneous and static structure; it has a heterogeneous composition and responds dynamically to applied loads. Neither should it be considered as an isolated structure because it interacts with the vertebral bodies, together constituting the vertebral unit. Furthermore, changes within the disc can, and do, have dramatic effects on vertebral column kinematics. The intervertebral disc is not inactive; it is capable of self‐maintenance; in injury it can repair itself and has considerable regenerative properties.