bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of immature leydig cells in the human prepubertal testis
Authors: Prince Frederick P.
Published: February 2005

The cellularity of the human prepubertal testicular interstitium has not been well studied at the ultrastructural level. In this study, testicular biopsies were obtained from 35 boys aged three to nine years and examined by electron microscopy to clarify and quantitate the cell types present during the prepubertal period.

The prepubertal testicular interstitium is found to consist of immature Leydig cells (9%), primitive fibroblastic cells (63%) (intertubular in location), and attenuated peritubular fibroblasts (28%). The primitive fibroblastic cells and peritubular fibroblasts appear closely related, being distinguished mainly by shape and location. The immature Leydig cell type contrasts with the fibroblastic cell types by exhibiting an irregular nucleus with relatively little heterochromatin. The most impressive cytoplasmic feature is the moderate to extensive development of smooth endoplasmic reticulum in the form of anastamosing tubules. In contrast, the rough endoplasmic reticulum is not well developed. Other cytoplasmic characteristics are the highly developed Golgi elements and occasional lipid droplets and lysosomes. Glycogen is also often present and is generally found in those cells that do not contain a welldeveloped smooth endoplasmic reticulum. The ultrastructure of the immature Leydig cell is compared with that of the mature fetal and adult Leydig cells. Although generally found in small clusters between tubules, these cells are often attenuated and closely associated with the seminiferous tubules. Occasional intermediate cell morphologies suggest a relationship between the primitive fibroblasts and immature Leydig cells.

The presence of small cells exhibiting a steroid‐producing morphology, classified as immature Leydig cells, in the prepubertal testicular interstitium is an interesting finding and is in accordance with earlier studies on nonhuman mammals. It is unknown whether these cells are remnants of the fetal Leydig cell population or have differentiated neonatally from the primitive fibroblastic cells. It is suggested that the immature Leydig cells are the progenitors of the adult Leydig cell population.
Disposition of the manchette in the normal equine spermatid
Authors: Goodrowe Karen L. , Heath Everett
Published: February 2005

Bielanski and Kaczmarski (1979) reported the presence of microtubules in the neck region of mature stallion spermatozoa. It was hypothesized that these microtubules are derived from the manchette (a microtubular organelle present during spermiogenesis). In order to test this hypothesis, testes from 15 mature stallions were collected, perfused with 2% phosphatebuffered glutaraldehyde, and prepared for transmission electron microscopy. Spermatozoa from the caudae epididymides of each stallion were prepared in a similar manner. Spermiogenesis was observed in general, and the presence of a microtubular manchette was established in this species, juxtapositioned posterior to the nuclear ring and extending distally into the cytoplasmic collar which surrounds the prospective midpiece. Interlocking arms between the microtubules of the manchette were observed in transverse sections at all levels within the cytoplasmic collar before, during, and after caudal migration of the nuclear ring. Consequent to caudal migration of the nuclear ring and the annulus, as well as adluminal movement of the spermatid, the cytoplasmic collar was transformed into the residual cytoplasm. Within the residual cytoplasm, the manchette remained as a microtubular organelle which undergoes degeneration. The mature spermatozoa from the caudae epididymides of these stallions lacked the microtubules reported by Bielanski and Kaczmarski. The occurrence of such microtubules in the neck region of stallion spermatozoa is probably an abnormality.
Endocytosis in epithelial cells lining the rete testis of the rat
Authors: Morales C. , Hermo L. , Clermont Y.
Published: February 2005

The endocytic activity of the low cuboidal cells lining the rete testis was analyzed by electron microscopy following injection of various tracers into the lumen of these anastomotic channels. At 1 and 5 minutes after injection, cationic ferritin (CF) and concanavalin A‐ferritin (Con A) were seen bound to the apical plasma membrane and to the membrane of subjacent vesicles or invaginations connected to this apical membrane. At 30 and 60 minutes, these tracers were found in intracytoplasmic vesicles and in vesicles connected to the lateral or basal plasma membrane as well as in the lateral intercellular space and in the lamina lucida of basal lamina. At 30 minutes, CF and Con A also appeared in the matrix of pale multivesicular bodies while at 1 hour dense multivesicular bodies were labeled. At 2 hours and later time intervals, the tracers accumulated in dense granules identified as lysosomes. Native ferritin (NF), concanavalin A‐ferritin in presence of α‐methyl‐D‐mannoside, and horseradish peroxidase or albumin bound to colloidal gold were all to be incorporated by the lysosomal system of these epithelial cells, as just described for CF and Con A, but these various tracers were not bound to the apical plasma membrane or to the membrane of cytoplasmic vesicles, nor were they found in the intercellular spaces or the lamina lucida at the base of the cells. Thus, the epithelial cells of the rete testis do not appear to be only involved in the uptake of substances from the lumen and their disposal by the lysosomal system, but also appear to contribute to the transport of certain macromolecules from the lumen to the laterobasal surfaces of the cells. These cells may thus play a role in determining the composition of the rete testis fluid.
Differentiation of cultured palatal shelves from alligator, chick, and mouse embryos
Authors: Ferguson Mark W. J. , Honig Lawrence S. , Slavkin Harold C.
Published: February 2005

Palatal shelves from embryonic alligators, chicks, and mice were explanted at various stages of development and organ cultured in either chemically defined, serumless media or the same media supplemented with 10% fetal calf serum. Shelves from each vertebrate were either cultured singly or in contact, and heterologous combinations of palatal shelves from different animals were made: chick/mouse, chick/alligator, and mouse/alligator. Epithelial differentiation (particularly that of the medial shelf edge) was assayed by vital staining, histology, and scanning electron microscopy. In vitro medial edge epithelial differentiation, and consequently the mechanisms of palatal closure, were identical to those normally seen in vivo for each species, i.e., cobble‐stoned migrating epithelia in the alligator, cell death and fusion in the mouse, and keratinisation and cleft palate in the chick. Differentiation was optimal in the chemically defined, serumless media and was independent of shelf contact in all three species. No heterologous combinations of palatal shelves closed with each other: Evidently, the modes of palatal closure in mice and alligators are sufficiently different to prevent them forming a chimeric palate, whilst neither is capable of inducing closure in a cocultured chick palatal shelf. These unified defined culture conditions make possible a large number of epithelial‐mesenchymal recombination studies as well as specific inhibitor, teratogenic, and hormonal investigations.
Some histochemical properties of the fiber types in the pectoralis muscle of an emu (Dromaius novaehollandiae)
Authors: Rosser Benjamin W. C. , George John C.
Published: February 2005

The muscle fibers of the cranial slip of M. pectoralis pars thoracica of an emu (Dromaius novaehollandiae) were studied histochemically for intracellular lipid, succinic dehydrogenase, myofibrillar adenosine triphosphatase, and acetylcholinesterase. It was concluded that the muscle consisted of approximately 28% slow‐tonic and 72% fast‐twitch glycolytic fibers. The tonic fibers were considered to be characteristic of a postural muscle, and the fasttwitch glycolytic fibers to reflect the inability of the muscle to engage in sustained activity. The general absence of slow‐tonic fibers from the pectoralis of other avian species so far studied may be attributed to inadequate sampling of the deeper regions of the muscle.
Circadian influence on the metaphase arrest technique in mouse cornea (light microscopy study) and rectum (flow cytometry study)
Authors: Burns E. Robert
Published: February 2005

Vincristine (VC) was used to arrest metaphases in the epithelium of the cornea and rectum. The cornea was studied by light microscopy (mitotic index). The rectum was analyzed by flow cytometry (%G2+M). The results of a dose range finding study showed that 3.0 mg/kg body weight VC did not increase the number of metaphases in the cornea or the %G2+M for the rectum over that recorded for a dose of 1.0 mg/kg VC. Therefore 1.0 mg/kg VC was selected as the dose to use. Mice were kept on a 12:12 light‐dark cycle with light from 0600 to 1800. Mice were treated with 1.0 mg/kg VC at either 0200 or 1400. 0200 is a time when the native mitotic index is increasing toward a peak level, which is attained at 0800–1000 under these conditions. 1400 is a time when the mitotic index is decreasing to trough level, which is attained at 2000 to 2200. In one experiment, subgroups of mice were killed at +3 (0500 or 1700) and +6 (0800 or 2000) hours after VC. In a replicate experiment subgroups were killed at +2 (0400 or 1600), +4 (0600 or 1800), and + 6 (0800 or 2000) hours after VC. The data from the cornea (mitotic indices) and the rectum (%G2+M) were graphed against time. For both organs the slope of the metaphase accumulation line was different when VC at 0200 data were compared to VC at 1400 data. The conclusion reached was that by changing the biological time of the experiment one can significantly change the slope of the line obtained with the stathmokinetic technique.
Iron deposition in the integument of lampreys
Authors: Youson J. H. , Sargent P. A.
Published: February 2005

The integument of larval, parasitic adult, and upstream‐migrant lampreys (Petromyzon marinus) was examined for iron deposition using light microscopic histochemistry and routine and histochemical procedures in the electron microscope. Ferritin particles, representing ferric iron, are present throughout most of the cytoplasmic matrix and within dense granules and vacuoles of epidermal mucous cells, but are not located in skein or granular cells. These particles are abundant in mucous cells of the dorsal surface but not the ventral surface and are more concentrated in adult lampreys compared to larva. Histochemistry revealed only sparse amounts of ferrous iron. Iron is not present in the dermis but is found in adipocytes of a subcutaneous layer. The deposition of integumentary iron is discussed with reference to body pigmentation and excretion of this metal.
Filamentous actin bundles in the kidney
Authors: Andrews Peter M. , Bates Sally B.
Published: February 2005

The distribution of filamentous actin bundles in the rat kidney was studied using a fluorescent phallotoxin label and transmission electron microscopy. The microvillous brush border lining proximal tubules, smooth muscle in renal vessels, and renal corpuscles were the structures most intensely labeled with rhodamine phalloidin. Closer evaluation of renal copuscles revealed intense labeling of filamentous actin within podocyte foot processes eveloping the glomerular capillary loops. Rhodamine phalloidin also labeled basal bands of filamentous actin in the parietal epithelium and basal bands of actin in proximal and distal tubules. Finally, a band of filamentous actin was evident along the innermost aspect of the kidney capsule, within cells which often joined to form sinus‐like compartments.
Cytoskeleton ultrastructure of podocytes and glomerular endothelial cells in man and in the rat
Authors: Vasmant Daniel , Maurice Michele , Feldmann Gerrard
Published: February 2005

The ultrastructural organization of the cytoskeleton of normal podocytes and glomerular endothelial cells was studied in man (adults and children) and in adult Sprague‐Dawley rats. In podocytes of both speicies, cytoplasmic microtubules (MT) were observed in the cell body close to the Golgi apparatus and along the main axis of the major processes where they formed bundles. A network of intermediate filaments (IF) was observed in the cell body and in the major processes where they sometimes formed bundles parallel to MT, especially in man. Numerous clustered microfilaments (MF) were noticed in the foot processes close to the plasma membrane. In glomerular endothelial cells from both species, networks of MT and IF were observed in the cell body, whereas MF surrounded the endothelial fenestrations. The high degree of organization of the cytoskeleton suggests that it may play an important role in several functions of both cell types.
Carbohydrate cytochemistry of rhesus monkey tracheal epithelium
Authors: St. George Judith A. , Nishio Susan J. , Plopper Charles G.
Published: February 2005

Three types of nonciliated secretory epithelial cells contribute material to the mucous lining of pulmonary airways: mucous cells, serous cells, and Clara cells. Extensive interspecies variation exists, especially between humans and laboratory mammals, with regard to occurrence, distribution, and granule content of these secretory cells. This study was designed to characterize one aspect of these differences in one species of nonhuman primate, the rhesus monkey. The complex carbohydrates of secretory granules present in the tracheal epithelium were characterized cytochemically. The tracheas of seven monkeys were fixed by airway infusion, processed, and embedded for both light and transmission electron microscopy. Histochemical stains including Alcian blue‐periodic acid Schiff, dialyzed iron, and high iron diamine‐Alcian blue were applied to serial methacrylate sections. The mucous cells were the predominant secretory cell type of the trachea and contained periodate‐reactive sulfated glycoconjugates. The mucous secretory granules, as resolved with the electron microscope, consisted of a mesh or matrix surrounding a biphasic core. The matrix was stained by all cytochemical reactions used, which included periodic acid‐thiocarbohydrazide‐silver proteinate, dialyzed iron, low iron diamine, and high iron diamine. The biphasic core also reacted with the four stains, but most intensely with high iron diamine. We conclude from this study that (1) the mucous secretory granule contains carbohydrate throughout all phases of the granule, (2) the mucous granule contains periodate‐reactive sulfated glycoconjugates, with sulfate esters concentrated in the core of the granule, and (3) the mucous granules of rhesus trachea morphologically and cytochemically resemble those described in human airways.
Ganglionic character of mesencephalic trigeminal neurons in the turtle Mauremys caspica
Authors: Fernández Elvira F. , Doel Rosa Paz
Published: February 2005

A study of the morphology of the mesencephalic trigeminal neurons and their arrangement in the optic tectum has been made in the turtle Mauremys caspica employing the Cajal reduced silver method. The ganglionic features of its neurons suggest that the mesencephalic trigeminal nucleus (MTN) is a diffuse sensory ganglion located in the central nervous system. The different distribution of two cell populations, probably as a result of a distinct embryonic origin of their elements, and the atypical pattern of the ependyma lying underneath the MTN are discussed.
Intercellular junctions in upper airway submucosal glands of the rat: A tracer and freeze fracture study
Authors: Schneeberger E. E. , McCormack J. M.
Published: February 2005

The structure of intercellular tight junctions of rat airway submucosal glands was examined by freeze fracture techniques and their permeability assessed by the use of colloidal lanthanum. The submucosal glands were organized into three distinct regions: (a) serous tubules and (b) mucous tubules lined, respectively, by serous and mucous cells, and (c) ducts lined by cuboidal epithelial cells, containing few secretory granules, and some ciliated cells. The mean number of parallel fibrils constituting the tight junctions between serous cells was 3.6 ± 0.4, which was significantly smaller than those between any of the other cell types. Colloidal lanthanum permeated the tight junctions between serous cells up to the level of the acinar lumen. There was a progressive increase in the mean number of parallel fibrils of tight junctions between mucous (5.1 ± 0.6), ductal (5.4 ± 0.5), and ciliated cells (8.5 ± 0.7); none of these junctions was permeated by colloidal lanthanum. These results imply that tight junctions between serous cells are more permeable to small water‐soluble solutes than those present in the more proximal portions of the gland. Gap junctions were observed between serous cells and between mucous cells, suggesting that these secretory cells may be electotronically and metabolically coupled.
A combined scanning electron microscopy and immunofluorescence study demonstrating that the odontoblast process extends to the dentinoenamel junction in human teeth
Authors: Sigal M. J. , Pitaru S. , Aubin J. E. , Ten Cate A. R.
Published: February 2005

The extent of the odontoblast cell process has been the subject of controversy for many years. Using SEM we have examined the extent and morphology of the process on dentine surfaces of human teeth which were partially demineralized and collagenase digested. Third molars were extracted and split; the dentine surface was demineralized, digested by bacterial collagenase, fixed with glutaraldehyde, postfixed in osmium tetroxide, and prepared for SEM investigation. The SEM study revealed the presence of many processlike structures which extended from the odontoblast cell bodies up to the dentinoenamel junction (DEJ). These processes demonstrated lateral and terminal branching and some of them terminated in distended spheres. We have also applied an immunofluorescence technique at the light microscope level to these exposed dentinal surfaces to localize the intracellular microtubules. For this, a second series of third molars was processed in the same manner as for the SEM up to the fixation stage. Teeth were then fixed in periodate‐lysine‐paraformaldehyde, postfixed in −20°C acetone, and then incubated with affinity‐purified rabbit antitubulin antibodies, followed by fluorescein‐conjugated goat antirabbit IgGs. Intratubular immunofluorescence labelling for tubulin was evident from the odontoblast cell bodies up to the DEJ. The presence of the tubulin‐containing structures extending to the DEJ supports the hypothesis that the structures observed with the SEM are odontoblast processes and that the odontoblast processes do extend to the DEJ.
Ultrastructure of the parotid gland in the little brown bat
Authors: Tandler Bernard , Cohan Richard P.
Published: February 2005

The ultrastructure of the parotid gland was examined in the little brown bat. The seromucous acinar cells contained abundant granules of variable morphology. These granules were characterized by a submembranous dense layer consisting of fine parallel slats. In some bats, the matrix of the granules was structureless, whereas in others it consisted of closely packed but randomly arranged bundles of tubules. The intercalated ducts had a highly developed rough endoplasmic reticulum, often containing large numbers of intracisternal granules. In contrast, only a few secretory granules were present in the supranuclear cytoplasm. The striated ducts, which exhibited the characteristic basal striations consisting of vertically oriented mitochondria and highly folded plasmalemmas, contained numerous small dense granules in a subluminal band. These granules had a paracrystalline substructure with a periodicity of 8 nm. Excretory ducts strongly resembled striated ducts. They showed the same kind of basal striations and about half their constituent cells contained small paracrystalline granules.
The ultrastructure of oral (buccopharyngeal) membrane formation and rupture in the anuran embryo
Authors: Watanabe Kyozo , Sasaki Fumie , Takahama Hideki
Published: February 2005

The ultrastructure of the oral (buccopharyngeal) membrane was examined by transmission and electron microscopy in the anuran, Rana japonica, embryo. The stomodeum is recognizable on the ventral surface anterior to the neural folds as the neural folds are beginning to close (neural tube stage). The stomodeum is gradually enlarged and deepened as development proceeds. At the neural tube stage, the oral membrane is 5–7 cell layers thick and the stomodeal ectodermal cells are cuboidal and the foregut endodermal cells are cuboidal or columnar. Desmosomes and basal lamina could not be found between the ectodermal and endodermal epithelia. The oral membrane gradually thins between the neural tube and hatching stages. At the hatching stage, the oral membrane becomes two or three cell layers thick and each cell is flattened. Many perforations of the oral membrane occur after hatching and the oral membrane appears “net‐like.” Necrotic cells occur in the oral membrane and these cells contain many autophagic vacuoles. ACPase‐positive lysosomes, Golgi regions, and autophagic vacuoles were present in the oral membrane. At the asymmetrical trunk stage, a large part of the oral membrane disappears and only remnants are left.
An implant labeling technique employing sable hair probes as carriers for 3H‐thymidine: Applications to the study of facial morphogenesis
Authors: Patterson Scott B. , Johnston M. C. , Minkoff R.
Published: February 2005

An implant labeling technique is described that utilizes sable hair probes as carriers for a tritiated thymidine marker. The protocol that was developed produced localized labeling of specific embryonic cell populations. This procedure was applied to the analysis of facial process development in chick embryos.

Evaluation of the technique demonstrated that the probe preparation procedure was consistently successful in producing labeled probes. Using labeled probes, the procedure was reliable in producing acceptable levels of labeling in chick embryonic tissues and labeling of localized cell populations was possible using the implant labeling technique. Surrounding the center of labeling, a gradient in intensity of labeling was often observed. This pattern presumably reflects declining availability of labeled thymidine as distance from the probe increased. The technique allowed excellent survival rates to be achieved provided that aseptic procedures were followed. Additionally, careful analysis of older embryos failed to reveal any malformations induced by the implant labeling procedure.

The localized labeling patterns that were demonstrated during this investigation suggest that the implant labeling technique would provide a useful tool for following cell migration during facial process formation.
Morphogenesis of chordae tendineae. I: Scanning electron microscopy
Authors: Morse Dennis E. , Hamlett William C. , Noble Charles W.
Published: February 2005

The formation of the chordae tendineae of the left atrioventricular valve in the chick embryo is described using scanning electron microscopy. These supportive structures for the valve cusps develop between days 6 and 13 of incubation. Elevations which represent the primitive papillary muscles form on the ventricular wall. These elevations bifurcate into thin, weblike folds which are attached to the primitive valve cusps. The folds are the primordia of the chordae tendineae. Linear ridges develop on the web between the cusp and papillary muscle. These ridges alternate with depressions. The depressions become perforate to create the individual chorda from the linear ridges. Multiple perforations form initially but they typically consolidate to create one large aperture between two chordae. Some interchordal connections of tissue do persist throughout the period studied. During the period of perforation, prominent rounded cells are typical of the endocardium between the chordae. These cells are similar at the scanning electron microscope level to those present in the formation of the foramina secunda of the atrial septum. Primary, secondary, and tertiary chordae tendineae appear to develop in the same manner. First order chordae (those attached at the free margin of a cusp) are not found in the chick embryo. The majority of the chordae are second order, which insert into the ventricular surface of the cusp a short distance from the free edge. These chordae typically have a horizontal banding or grooving along their length. Third order chordae which extend from the papillary muscle to the ventricular wall are also present. It is suggested that chordal development is a programmed cellular and hemodynamic event.
Morphometry of articular cartilage: A stereological method using light microscopy
Authors: Paukkonen Kari , Selkäinaho Kalevi , Jurvelin Jukka , Helminen Heikki J.
Published: February 2005

A stereological method is introduced for studying the light microscopic morphometry of articular cartilage. New parameters are presented for defining the three‐dimensional structure of the articular cartilage. These include volume density of the lacunae and nuclei, numerical density of cells in 3‐dimensional space, total number of cells, total volume of the lacunae in cartilage, volume and diameter of the lacuna and nucleus, the nucleus/lacuna volume ratio, and the mean volume of the matrix per cell. Using the lateral tibial condyle of the knee joint of eight rabbits, we investigated tissue preparation, sampling, morphometry, and the conditions necessary for validity and precision of the estimators. The method proved easy to use, and the estimators were precise.
A simplified method for hand‐made oblique graphical reconstructions
Authors: Claeys Hendrik , Aerts Peter
Published: February 2005

The present paper deals with a convenient, manual method for making oblique graphical reconstructions from serial sections. The method is based on a projection on the plane of drawing of a three‐dimensional coordinate system, which is submitted to two successive and predetermined spatial rotations. Restriction to two rotations simplifies the mathematical approach to a coordinate transformation from a three‐dimensional into a two‐dimensional system. The resulting formulae, which are quite easily applied, lead to a quick visualization procedure.
Ultrastructural localization of carbonic anhydrase in lysosomes
Authors: Rikihisa Yasuko
Published: February 2005

Ultrastructural localization of carbonic anhydrase was determined by applying Hansson's histochemical method to glutaraldehyde‐fixed frozen sections of guinea pig peritoneal polymorphonuclear leukocytes (PMNs) and lysosomes isolated from rat liver tissue after the animal had been injected with Triton WR‐1339. A positive histochemical reaction for carbonic anhydrase in PMNs was found in the matrix of lysosomes. After PMNs phagocytized polystyrene latex particles or emulsified paraffin oil droplets, a positive reactivity for carbonic anhydrase was found in the space between the lysosomal membrane and the particle. Liver lysosomes also revealed positive carbonic anhydrase histochemical reactivity. To confirm the histochemical reaction, indirect immunoferritin labeling was conducted with rabbit antibody to human red blood cell carbonic anhydrase C on glutaraldehyde‐fixed, freezethawed human PMNs. Immunolabeling was observed in lysosomes. These results suggest that carbonic anhydrase is a constituent of lysosomes of PMNs and liver cells.
Development of mouse embryos in hanging drop culture
Authors: Potter Sandra W. , Morris John E.
Published: February 2005

Mouse blastocysts were cultured in hanging drops for up to 6 days in order to study development under conditions that avoid the distortion of embryos typically seen when they are allowed to attach to a glass or plastic surface. The survival rate of embryos in hanging drops was equal to that of embryos attached to culture dishes and superior to that of embryos suspended in gyrating flasks. Development of the embryonic portion was similar to that in vivo and on culture dishes but slower than in vivo; the egg cylinder stage was reached after 8–10 equivalent gestation days (4 to 6 days in culture), while that stage is reached at 5.5 to 6 days in vivo. The trophectoderm, however, developed in a unique manner. The cells migrated away from the inner cell mass (ICM), similar to embryos on a culture dish, but without a surface on which to spread they clustered distal to the ICM. In vivo, trophectoderm remained covering the ICM. By 5 days in hanging drop culture the embryos had developed a segmented appearance with trophoblast giant cells at the abembryonic pole, extraembryonic cells not covered by vacuolated endoderm in the central region, and embryonic endoderm surrounding a developing proamniotic cavity in embryonic ectoderm at the embryonic pole. These observations suggest that the trophectoderm is able to follow a developmental program independent of that in the embryonic portion and that its behavior is dominated by the different adhesive properties of the trophoblastic and embryonic cells.
Spinal tanycytes in the adult rat : A correlative Golgi gold‐toning study
Authors: Rafols José A. , Goshgarian Harry G.
Published: February 2005

In Golgi impregnated transverse sections through the cervical spinal cord of the 7–12‐week‐old adult rat, numerous tanycytes were observed radiating from the ependyma into the gray matter that surrounds the central canal. The tail processes of these tanycytes terminated as foot processes in association with blood vessels. Spinal tanycytes were classified into ependymal (E) and subependymal (S) types on the basis of the shape and position of the soma. The soma of the E tanycyte was shaped as a column and was entirely located within the ependyma. In contrast, the soma of the S tanycyte was flask shaped, with the widest portion of the flask located subependymally and the elongated portion extending through the ependyma ultimately reaching the luminal surface. Selected Golgi impregnated sections were gold toned and deimpregnated for direct correlative analysis at the ultrastructural level. Gold‐toned tanycytes contained the fine clusters of gold particles underlying the plasma membrane of the cell body and coarse clusters of gold particles throughout the tail and foot processes. The apical surface of tanycytes was characterized by numerous microvilli and large cytoplasmic protrusions that evaginated from the apical surface into the lumen of the central canal. At the luminal surface, adjacent tanycytes were joined laterally by junctional complexes with punctate tight junctions and zonulae adhaerentes associated with fibrils and microtubules. In contrast, gap junctions, hemidesmosomes, and puncta adhaerentia were found between adjacent tail processes of tanycytes. The foot processes interdigitated with one another and abutted the basal lamina around the perivascular space of blood vessels. The basal lamina was continuous around the lateral walls of foot processes and filled the spaces between membranous infoldings of the lateral walls. These basal membrane labyrinths were continuous with the basal lamina of the blood vessel and may provide an extensive surface relation between the perivascular space and the neighboring extracellular compartment. The findings of the present study support the contention that tanycytes may modify the composition of substances moving between the perivascular and extracellular spaces.
Statistical significance tests for autoradiographic data
Authors: Skipper Betty J. , McGuffee Linda J.
Published: February 2005

The purpose of this paper is to develop statistical methods that take radiation spread into account in analyzing data from different autoradiographic experiments. The method uses the probability circle analysis of Salpeter and McHenry (1973) to obtain the probable source of each radioactive emission and the circle and point counting method of Williams (1969) to estimate the relative area occupied by each cellular site. Two levels of analysis are presented. The first level of analysis is concerned with estimating relative activities and standard errors for cellular items that are larger than the probability circle. The second level of analysis involves estimating relative activities and standard errors for cellular sites that are smaller than the probability circle and are therefore observed in circles containing another item such as cytoplasmic matrix. Two different tests of hypotheses are discussed. The first null hypothesis is that the radioactivity is randomly distributed among the cellular sites. The second null hypothesis is that there is no difference between two different treatments in the relative activities for a given site.
Odontoblast turnover in the impeded and unimpeded rat incisor derived from computerized histomorphometry
Authors: Weinreb M. , Steigman S. , Zajicek G. , Michaeli Y.
Published: February 2005

A computerized histomorphometric method was devised to estimate the kinetics of odontoblast turnover and dentinogenesis in rat incisors. The method was applied to two groups of rats: one group with lower incisors in impeded eruption and another group with the left lower incisor in the unimpeded state. The teeth were divided into six equal segments, from which consecutive ground sections were obtained. The distance of each ground section from the posterior border of the alveolar bone was calculated. Each section was magnified, traced, and the tracings fed into a computer by a sonic digitizer. The perimeters and areas of dentine and pulp in each ground section were calculated by the computer. The mean odontoblast density along the predentine was evaluated from histological sections taken both from the same tooth segments and from teeth sectioned midsagittally. These served for the estimation of the predentine area occupied by the average odontoblast. In the impeded group, this area was 11% larger than in the unimpeded one. Outer dimensions of teeth, namely the circumference of the dentine, the labiolingual width, and the mesiolateral width remained constant and equal for both groups.

Daily rates of dentine apposition were computed and were found to vary according to the age of the odontoblasts. Odontoblasts of impeded teeth started to secrete matrix at a rate of 17 μm/day, which increased slightly to 19 μm/day and later declined to 7 μm/day on the 38th day. Dentine production of unimpeded odontoblasts, on the other hand, started at a rate of 16 μm/day and gradually increased to 34 μm/day on the 17th day. The daily rate of odontoblast cell‐production was 2.29 times greater in the unimpeded teeth (112.9 × 103 cells/day instead of 49.4 × 103 cells/day). The absolute mean daily rate of odontoblast cell loss increased in unimpeded teeth from 33.1 × 103 cells/day to 42.9 × 103 cells/day. On the other hand, the relative daily rate of cell loss decreased from 73.6 cells/day/1μm eruption to 47.7 cells/day/1μm eruption.
Activation of actin‐containing microfilaments by vasopressin in the amphibian urinary bladder epithelium: A fluorescent study using NBD‐phallacidin
Authors: Davis Walter L. , Gwendolyn Jones Ruth , Richemont Phillip C. , Goodman David B. P.
Published: February 2005

The effect of an antidiuretic hormone (ADH, vasopressin) on the microfilament system of the toad urinary bladder lumenal epithelium was investigated using NBD‐phallacidin (NBD‐ph). The latter material is a specific fluorescent label for F actin. In the presence of an osmotic gradient, both ADH and cyclic adenosine monophosphate (cAMP) appear to induce the polymerization of monomeric actin into F actin‐containing microfilaments. The latter may then be involved in the morphological changes, including the formation of lateral intercellular lakes, associated with the typical hydroosmotic response.
Fluid‐phase and adsorptive endocytosis in ciliated epithelial cells of the rat ductuli efferentes
Authors: Hermo L. , Clermont Y. , Morales C.
Published: February 2005

Ciliated cells of the ductuli efferentes show at their apex a discrete endocytic apparatus composed of small vesicles connected to or subjacent to the apical plasma membrane, small apical membranous tubules, and pale multivesicular bodies. Deeper in the cytoplasm, there are acid phosphatase‐positive denser, multivesicular bodies and secondary lysosomes showing an electron‐dense cortex and a crystalline, paler stained core. Cationic ferritin and concanavalin A‐ferritin used to demonstrate adsorptive endocytosis, when injected into the rete testis, rapidly reached the lumen of the ductuli efferentes. At 1 min after injection, these tracers were seen bound to the apical plasma membrane of ciliated cells and within small endocytic vesicles and by 5 min in narrow apical tubules. At 15 and 30 min after injection, the tracers appeared in pale multivesicular bodies while at 1 hr they were found within dense multivesicular bodies. At 2 hr and longer time intervals these tracers accumulated within secondary lysosomes. Native ferritin, concanavalin A‐ferritin in the presence of α‐methyl‐D‐mannoside, and horseradish peroxidase or albumin‐colloidal gold complexes were used to analyze fluid‐phase endocytosis. At various intervals following their injection into the rete testis, these tracers presented a distribution identical in all respects to that described for cationic ferritin and concanavalin A‐ferritin. In the present work, none of the above tracers were transported to the abluminal aspect of the ciliated cells. These cells, like the nonciliated epithelial cells of the ductuli efferentes are thus involved in adsorptive as well as in fluid‐phase endocytosis.
Chronic changes in male rats' hormone‐sensitive systems after suprathreshold pulses of testosterone
Authors: Taylor George T. , Weiss Jürgen , Haller John
Published: February 2005

Adult male rats were castrated and maintained on daily SC injections of a threshold amount (200 μg) of testosterone propionate (TP). To mimic naturally occurring pulses of suprathreshold testicular hormones in intact males, animals in the experimental groups also received either one (single TP) or five (multiple TP) injections of 800 μg TP over 12 days. The rats were examined on the following day (acute) or 15 days later (chronic) for changes in hormone‐sensitive behavior, physiology, and morphology. The hypothesis tested was that the hormonal pulses function to provoke chronic changes in substrates underlying the reproductive system. The results were that multiple doses of suprathreshold TP provoked acute modifications in aggressive behavior, sex accessory glands, and glans penis integrity. Chronic changes were observed in sex accessory gland functioning and penile morphology, particularly in the size of penile papillae. A single exposure to suprathreshold TP was considerably less effective, though there was some evidence of acute changes in sex accessory glands and chronic changes in penile papillae. There was substantial variation in the responses of individual animals, particularly the chronic responses. The data were interpreted as supporting the hypothesis.
Quantitative and comparative stress analysis in human femur under two different static situations by three‐dimensional photoelasticity
Authors: Bianchi Rossella , Clerici Paolo , Miani Alberto
Published: February 2005

Using the three‐dimensional photoelastic method a quantitative analysis was carried out on the tension trends in the proximal third of a normal human femur in a stationary weight‐bearing situation on two legs.

The results obtained show that in this loading situation the maximum stress values (both for tension and compression) are in the area just below the subtrochanteric zone; while going up along the borders of the diaphysis, the tension trends do not vary appreciably.

Moreover, the state of the stresses is not constant but varies slightly along the thickness of the bone. The neutral axis is considerably displaced towards the tensile area.

A comparison between the stress tension trends in two different static loading situations (one‐leg and two‐leg support) was carried out.

It was found that the maximum tensile stress value in the one‐leg position was about 24 times greater than that in the two‐leg position and the maximum compression stress value was about 14 times greater than in the two‐leg situation.
A quantitative microprobe analysis of elements in cortical and nuclear cells of the calf lens
Authors: Neuringer Julia R. , Clark John I. , Benedek George B.
Published: February 2005

The outer cortical cells in the calf lens remain transparent under conditions that produce opacity in central nuclear cells. The nuclear cells opacify by a mechanism of cellular restructuring that is associated with a cytoplasmic phase separation while cortical cells do not opacify by this mechanism. In this study the differences in elemental composition of nuclear and cortical cells were analyzed using X‐ray emission spectroscopy (XES) of tissue that was prepared for scanning electron microscopy. It was necessary to develop special methods of fixation and dehydration to prevent significant distortion of lens tissue and minimize solubilization and redistribution of elements during the histological processing of the tissue. We calibrated the microprobe for the quantitative analysis using gelatin standards which contained known concentrations of sulfur, potassium, phosphorus, chlorine, and cesium. The standard curves were used to determine proportionality constants, which related the intensity of X‐ray emission to the molar concentration of each element, and to determine the minimum detectable levels of each element. An important finding is that the intensity of the X‐ray emission is dependent on sample density only at low protein concentration. At the high protein concentrations that exist in lens, the intensity is not affected by sample density. The results are that (1) normal concentrations of sulfur, phosphorus, and potassium can be localized using this procedure; (2) concentrations of sodium, magnesium, chlorine, and calcium are just below the sensitivity of the present method in the normal lens; 3) lenses that are placed in solutions of monovalent ions have increased concentrations of the ions in both the nucleus and cortex, but only the nuclear cells opacify; and 4) the greatest detectable difference between the cells in the lens nucleus, which opacify, and cells in the lens cortex, which do not opacify, is in the phosphorus content. Cortical cells contain five to six times as much phosphorus as nuclear cells.
Mucous cells and cell migration in the mouse duodenal epithelium
Authors: Bjerknes Matthew , Cheng Hazel
Published: February 2005

The distribution of mucous cells in the mouse duodenum was used to determine whether or not intestinal epithelial cells move as a sheet during their migration from crypts to villi. The experiments took advantage of the probable symmetry of mucous‐cell divisions (symmetry in the sense that each mucous‐cell division produces two mucous cells). Since approximately 50% of newly formed mucous cells are derived from mucous‐cell divisions, at least 50% of newly formed mucous cells in the crypt should be found in mucous‐cell pairs. It follows that if the epithelium moves as a firmly interconnected sheet, at least 50% of mucous cells found in the villus should also be in pairs. On the other hand, if a significant amount of cell mixing occurs during migration, the pairing tendency of mucous cells would be lost. Mucous‐cell pairing was determined by two independent methods: (1) direct observation of mucous‐cell pairs and (2) the application of Poisson statistics to the mucous‐cell distribution to determine a “pairing tendency.” We found that in the crypt at least 75–80% of newly formed mucous cells occur in pairs, while in all regions of the villus (base, middle, and top) mucous cells are distributed randomly. These results strongly indicate the existence of a significant amount of cell mixing in the epithelium at some point between the site of mucous‐cell formation in the crypts and the villus base. Since the mucous‐cell population was randomly distributed in all regions of the villus we were unable to determine whether or not additional cell mixing occurs in the villus epithelium.
Substance P immunoreactivity in the major pelvic ganglion of the rat
Authors: Dail William G. , Dziurzynski Rene
Published: February 2005

Substance P immunoreactivity in the major pelvic ganglion (MPG) of the rat was studied to define a possible role for this neuropeptide in functions of the pelvic portion of the autonomic nervous system. Substance P immunoreactivity was found in three locations in the ganglion: (1) as a plexus of varicose fibers, (2) in small intensely fluorescent (SIF) cells, and (3) after colchicine pretreatment, in some principal neurons. The perineuronal plexus of fibers appeared as small varicosities closely related to the somae of principal neurons. Approximately 10–20% of principal neurons were enclosed by a substance P‐positive plexus. SIF cells were intensely stained for substance P. The general relationships of SIF cells in this ganglion were confirmed by their staining for substance P: their occurrence singly or in large clusters, their short tapering processes often related to principal neurons, and the occasional presence of a beaded process. Colchicine treatment resulted in the appearance of rare principal neurons that stained for substance P. The pelvic nerve was surgically interrupted to determine whether the perineuronal plexus of varicose fibers had an intrinsic origin or arose from cell bodies outside the ganglion. The perineuronal plexus was virtually absent following this procedure. The results of this study indicate that principal neurons in the major pelvic ganglion may be subject to the influence of substance P derived from two sources: (1) intrinsic substance P‐containing SIF cells and (2) neurons probably residing in dorsal root ganglia. The nature of principal neurons that acquire staining for substance P after colchicine is unclear.
Muscle cell membranes from early degeneration muscle cell fibers in Solenopsis are leaky to lanthanum: Electron microscopy and X‐ray analysis
Authors: Jones Ruth Gwendolyn , Davis Walter L.
Published: February 2005

Lanthanum infusion techniques, transmission electron microscopy, and X‐ray microanalysis were utilized to compare the permeability of muscle cell membranes from normal and degenerating muscle fibers of Solenopsis spp. In normal fibers, the electron‐dense tracer was limited to components of the sarcotubular system. However, the insemination‐induced degeneration of muscle fibers was characterized by the presence of an electron‐dense precipitate within the myofibrils and mitochondria as well as in the extramyofibrillar spaces. The electron‐dense material was subsequently identified by elemental analysis to be lanthanum. Such data indicate that one of the earliest stages of muscle degeneration involves an alteration in cell membrane permeability.