bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone formation is not coupled to bone resorption in site‐specific manner in adult rats
Authors: Chow Jade W. M. , Badve Sunil , Chambers Timothy J.
Published: February 2005

The trabecular bone of the secondary spongiosa of mature rats shows a coupling of bone formation to resorption. It has been clearly shown that in adult man the coupling of formation and resorption involves a site‐specific sequence of events, in which bone resorption is normally followed, at the same site, by bone formation. Whether the coupled processes of bone resorption and formation also occur at the same site in the rat is controversial. To elucidate the spatial relationship between bone formation and resorption in the rat, we compared the percentage of crenated and non‐crenated cement lines with the percentage of crenated and non‐crenated bone surfaces in the proximal tibia of adult rats aged 16 weeks to 2 years. A similar comparison was also made using bone from adult human iliac crest.

We found that the trabecular bones of 16‐week‐old and 7‐month‐old rats exhibited a low percentage (7–11%) of crenated cement lines, which is opposite to the proportion (88%) we observed in human trabecular bone. In contrast, the surfaces of rat bone trabeculae showed a similar low proportion of crenated surface to human bone (rat 1.1–1.4% vs. 5% in humans). In older (2 years) rats, in which bones have ceased to grow in length, the percentage of cement lines that were crenated increased to 45%. These results imply that the major proportion of bone formation in the trabecular bone of growing rats occurs on non‐resorbed surfaces. Thus, although there is substantial evidence that bone formation is coupled to resorption in the rat, such that increased resorption is associated with increased formation, and suppression of resorption suppresses bone formation, bone formation does not necessarily occur on a previously resorbed site. This suggests that in the rat, the processes are not coupled by local release of cytokines or local cell interactions but by some other signal, such as mechanical stimulation. Since site‐specificity appears not to be crucial to the coupling of formation to resorption, the greater site‐specificity of coupling in man, and in older rats, may be attributable to a more static skeleton, which engenders a closer spatial correlation between bone formation and the resorption that induced it. © 1993 Wiley‐Liss, Inc.
Stereological study of mouse uterine and in vitro grown blastocysts: Cell numbers and volumes
Authors: Hurst Peter R. , Leeuwenberg Brenda R. , Ellis Leslie M.
Published: February 2005

Mouse blastocysts were studied to determine if there were differences in cell number and volumes between those that were (1) derived from the uterus prior to implantation on the afternoon of day 4 of pregnancy and (2) those that were cultured for 72 hr from two‐cell‐stage embryos. Blastocysts were fixed, embedded in resin, and serially sectioned at 1.5 or 2 μm. Photographic prints of alternate sections were used to count the numbers of inner cell mass (ICM) and trophectoderm cells. Cavalieri's direct estimator was applied to the same prints to estimate the volume of the whole blastocyst. Point counting was used to determine the volumes of the ICM, trophectoderm, and zona pellucida. The number of cells and size of the ICM were similar between the two groups of blastocysts, although it was found that the ICM of uterine embryos that did not have a zona pellucida were smaller than the ICM of those that did. There were twice as many trophectoderm cells in the blastocysts that were cultured from two‐cell embryos, and these cells were also found to be larger. Furthermore, the volume of the zona pellucida was less in the uterine blastocysts. This study indicates that, while trophectoderm proliferation is enhanced in vitro, the ICM is more constant and thus may be self‐regulating and independent of the growth conditions of the blastocyst as a whole. This study also suggests partial zona lysis occurs in utero and occurs either at a reduced rate or not at all in vitro. © 1993 Wiley‐Liss, Inc.
Structural and functional properties of trophoblast cells of mouse egg‐cylinders in vitro
Authors: Olovsson Matts , Nilsson B. Ove
Published: February 2005

Embryos at the egg‐cylinder stage were obtained by culturing blastocysts in vitro on an agarose surface for 4 days. The adhesiveness and outgrowth activity of the trophoblast of the egg‐cylinder were compared with those properties of the flushed adhesive blastocyst. Trophoblast cells of egg‐cylinders were found to be more adhesive and their outgrowth activity greater than in the case of trophoblast cells of adhesive blastocysts. The cultured egg‐cylinders presented two subpopulations of giant trophoblast cells. They represent probably two stages of differentiation of the same trophoblast population. The most distinctive morphological differences of these subpopulations were that the surface of one was covered with small blebs and the cytoplasm had relatively few ribosomes, while the surface of the other subpopulation was covered with large blebs and microvilli and the cytoplasm was rich in ribosomes and large, dense granules. The two types of giant trophoblast cells of the day 7 implantation site consist of one subpopulation whose cytoplasm has few organelles, and the other subpopulation, whose cytoplasm is rich in ribosomes, lysosome‐like bodies, and heterophagosomes. Hence, we conclude that the in vitro grown trophoblast cells have counterparts in the in vivo implanting embryos. The lectin binding pattern of the agarose cultured egg‐cylinder trophoblast cells was similar to that of the adhesive and/or invasive trophoblast cells grown in vivo.

Thus, the in vitro grown egg‐cylinders are appropriate material for the analysis of trophoblast cells at the invasive stage of implantation. © 1993 Wiley‐Liss, Inc.
Occurrence of a third type of secretory cell in the acinus of the rat submandibular gland
Authors: Nagato Toshikazu , Nagaki Masami
Published: February 2005

A new, third type of secretory cell was found in the acini of the submandibular gland in rat. In paraffin sections stained with hematoxylin‐eosin or reacted with periodic acid‐Schiff, acini containing the third type of secretory cells were found as a mass of darkly stained secretory endpieces at the periphery of the lobule. In semi‐thin sections stained with toluidine blue, these cells showed numerous dense secretory granules in their cytoplasm. Some acini consisted entirely of these cells, whereas other acini consisted of an admixture of such cells and typical seromucous cells. Acini containing the third type of secretory cell tended to form clusters. Electron microscopically, the cells had well‐developed rough endoplasmic reticulum and Golgi apparatus. The secretory granules showed a wide range of variation in substructure, even within the same cell. Well‐developed intercellular interdigitation and intercellular canaliculi also were observed between adjacent third type of secretory cells. Although little is known about the biological significance of these cells and the properties of their secretory granules, the present study shows that the rat submandibular gland possesses three types of secretory cells in their secretory endpieces. © 1993 Wiley‐Liss, Inc.
Ultrastructural characteristics of primordial germ cells in the quail embryo
Authors: Yoshinaga Kazuya , Nakamura Masao , Ukeshima Atsumi
Published: February 2005

An avian species, the quail has become a desirable animal model in experimental embryology and reproductive biology. To understand the ultrastructural characteristics of primordial germ cells (PGC) of this species, we studied PGC in the Japanese quail (Coturnix coturnix japonica) embryo at various developmental stages from their appearance in the germinal crescent through migration to settlement in the gonadal ridges by means of electron microscopy. The results were compared with those of another well‐known avian species, the chick. Several ultrastructural characteristics of quail PGC not described previously in chick PGC were observed as follows: (1) No glycogen particles were detected in the cytoplasm at any stage examined. (2) Electron‐dense and membrane‐bounded granules were found in the PGC cytoplasm during the sexually indifferent gonadal stages. (3) Quail PGC were characterized by a prominent nucleolus associated with condensed chromatin (heterochromatin), and the developmental changes of the nucleus, were noted; the nucleolus initially appeared as a compact mass at the germinal crescent stage and became dispersed at later stages during the colonization of the gonadal ridges. These findings suggest several physiological and functional differences in the cell cycle between these two avian species. This is the first report describing detailed ultrastructural characteristics of PGC in the quail embryo. © 1993 Wiley‐Liss, Inc.
Fine structure and subepithelial capillaries of the main excretory duct epithelium of the submandibular gland of the Japanese monkey, Macaca fuscata
Authors: Sato Atsuko , Toh Hidetoshi , Miyoshi Sakuichiro
Published: February 2005

The fine structure and subepithelial capillaries of the main excretory duct epithelium (MEDE) of the submandibular gland in the Japanese monkey, Macaca fuscata were investigated by light, scanning, and transmission electron microscopy. Capillaries found beneath the MEDE were all fenestrated ones. Some of them had elevated endothelium known as pored domes. The capillary density (number of capillaries per 200 μm length of MEDE) was 6.05 ± 1.36, and the number of fenestrae per 10 μm length of available endothelium was 11.62 ± 3.82. The MEDE was pseudostratified, and consisted of four cell types: Type I and II, which were columnar cells without basal infoldings, basal and goblet cells. The most characteristic feature was the presence of well‐developed lateral interdigitations between Type I and II cells. © 1993 Wiley‐Liss, Inc.
Comparison of muscle cell fiber types and oxidative capacity in gracilis, rectus femoris, and triceps brachii muscles in the ferret (Mustela putorius furo) and the domestic dog (Canis familiaris)
Authors: Amann John F. , Wharton Robin E. , Madsen Richard W. , Laughlin M. Harold
Published: February 2005

Muscle cell fiber types in gracilis, rectus femoris, and long head of triceps brachii muscles of ferrets and dogs were identified on serial sections stained for myosin ATPase after preincubation at pH values of 9.8, 4.6, and 4.3 and for NADH‐tetrazolium reductase (NADH‐TR) activity. Although fiber types I and II were identified, the ATPase stain did not demonstrate classic type IIA/IIB fiber differences in either species. However, two type II fiber subtypes could be distinguished in the ferret because they differed slightly in staining intensity with ATPase at pH 4.3 and markedly with NADH‐TR. One ferret type II fiber (designated II dark or IID) was smaller, slightly darker on ATPase, more oxidative on NADH‐TR, and comprised more muscle volume than the other type II fiber (designated II light IIL). The IID fibers of ferret may represent the IID/X fibers of other authors. Both ferret type II fiber subtypes stained darker at pH 4.3 than canine II fibers. The NADH‐TR staining indicated high oxidative activity in canine and ferret type I fibers. In contrast, type II fibers in the dog and IIL fibers in the ferret were moderately oxidative. Canine type IIC fibers were intermediate between type I and type II, whereas in the ferret, type IIC fibers were highly oxidative, as were type IID fibers. Ferret muscles are more oxidative than canine muscles according to NADH‐TR staining. Also, ferret muscles possess 40–100% higher citrate synthase activity as compared to canine muscles. © 1993 Wiley‐Liss, Inc.
The microvilli and hyaline layer of embryonic asteroid epithelial collar cells: A sensory structure to determine the position of locomotory cilia?
Authors: Crawford B. J. , Campbell S. S.
Published: February 2005

Early stage embryos of the starfish Pisaster ochraceus exhibit one cilium per cell which is primarily involved in locomotion. SEM observations have demonstrated two types of microvilli “stage horn”‐like and “finger‐like” microvilli (CMs), both of which probably serve to anchor and support the hyaline layer (HL). The CMs arise from the cellular membrane a short distance from the base of the ciliary shaft and form a circle around the base of each cilium. This arrangement is found in embryos and larvae as well as in adult tissues of many other marine organisms. TEM observations of material prepared by freeze substitution has demonstrated that the HL unites the circle of CMs and forms two collars. The outer ECM collar is single and attached directly to the CMs, while the inner collar consists of multiple rings of ECM located between the cilium and the CMs. The inner collar elements are not attached to the cilium but are attached to the inner aspects of the CMs by a complex arrangement consisting of a loop of ECM and two short ECM fibers. The arrangement of the ECM of the collars could provide an excellent way to transmit the movements of the cilium to the surrounding microvilli. Although the bases of the CMs always encircle the ciliary shaft, the shafts of the CMs are seen in different positions. This suggests that the CM/ECM collar may be able to change position relative to the cilium. Confocal laser scanning microscopy demonstrates that the CMs contain phalloidin positive material which extends into a phalloidin positive region located in the apex of the cells. The CMs and apical web contain microfilaments which are probably actin and could be involved in movement of the CMs. A movable circle of CMs with their associated ECM could represent a mechanism to sense the position of the cilium and/or to define the direction and extent of the stroke. © 1993 Wiley‐Liss, Inc.
Natural wound formation: Endodermal responses in experimental primary neural induction in the chick embryo
Authors: England Marjorie A. , Lawson Aaron
Published: February 2005

Natural wound formation in experimental primary neural induction has been studied by SEM and in paraffin wax sections in embryos from 0 minutes to 10 hours of re‐incubation. Stage 4 host and graft embryos were removed from hen's eggs and mounted as for New culture. Graft Hensen's nodes were transplanted into “pockets” created in the host area pellucida and re‐incubated for up to 10 hours.

Initially the cut edges of the graft establish contact with the host ectoderm layer. After 4 hours the cut edges of the graft move from the host ectoderm to the host endoderm layer. Several small openings form in the host endoderm over the graft tissue. By 6 hours, these openings join to form a single natural wound through which the underlying graft is exposed to the external environment. At 8 hours the graft forms a head‐fold and neural folds are evident. During 8 to 10 hours of re‐incubation the edges of the graft which attach to the edges of the host edoderm meet in the midline and close the opening in the host endoderm; simultaneously, the graft forms a neural tube.

The endodermal wounds form by cell re‐arrangement and by a minor contribution from cell loss. © 1993 Wiley‐Liss, Inc.
Light and electron microscopic analysis of two divisions of the suprachiasmatic nucleus in the young and aged rat
Authors: Woods William H. , Powell Ervin W. , Andrews Annette , Ford Charles W.
Published: February 2005

The suprachiasmatic nucleus (SCN) is a principal controller of mammalian circadian rhythms. However, in spite of documented disturbance of biological rhythms in old animals, few significant age‐related changes have been observed in this nucleus. This study examined age‐related differences in SCN volume, neuronal number, density, and ultra‐structural features in the entire rat SCN and in its two divisions, the denser ventromedial (compacta) and less dense dorsolateral (dissipata). Light and electron microscopic morphometric techniques were utilized in weanlings (21–28 days), young adults (3–6 mo), and aged (30–36 mo) animals.

The total SCN volume, as well as volumes of‐the compacta regions, were significantly greater in young adult and aged rats than in weanlings. Thus, as the rat ages the SCN increases in total size. However, the dissipata region appears to decrease in volume while the compacta increases. Even though the total number of SCN neurons was quite constant in the three age groups, the number of neurons in the dissipata region was decreased significantly in the young adult and aged groups as compared to the weanling.

Neurons in the compacta region were usually spindled‐shaped with two dendritic processes, while oval to spheroidal cells with 3–4 processes predominated in the dissipata. Nuclei of SCN cells were often invaginated. In weanlings, more SCN neuronal nuclei had invaginated nuclei in the dissipata region (66%) compared to the compacta (37%). In the two older age groups of rats, a higher percentage of invaginated neuronal nuclei were found in both regions. However, more were still found in the dissipata (90%) compared to the compacta (72%), even though the number of these cells in the compacta doubled. Thus, there was a large increase in the number of invaginated nuclei, as well as the number of invaginations, in the young adult rats compared to the weanling group, and this increase persisted in aged rats.

SCN neurons usually had nuclei surrounded by a thin perimeter of cytoplasm containing sparse mitochondria and granular endoplasmic reticulum, multiple Golgi regions, and a moderate number of free ribosomes. In weanlings, mitochondria contained dense cristae and the granular endoplasmic reticulum was relatively prominent. Degenerative ultrastructural changes which included mitochondrial enlargement/vacuolation, Golgi vacuolation, lysosome, and lipofuscin development occurred in less than 10% of young adult SCN cells, and were more frequently found in the dissipata. In aged, rats 30% of the neurons showed degenerative changes in the dissipata compared with 18% in the compacta. Degenerative changes appeared highly correlated with the degree of membrane folding. Ultrastructural degenerative cell changes and light microscopic morphometric observations are discussed in relation to loss of circadian rhythms with advancing age. © 1993 Wiley‐Liss, Inc.
Quantitative morphological changes in neurons and glia in the frontal lobe of the aging rat
Authors: Peinado Maria Angeles , Martinez Manuel , Pedrosa Juán Angel , Quesada Adoración , Peinado José Maria
Published: February 2005

The quantitative morphological changes in neurons and glia during the aging process were analyzed in the different cortical layers, grouped as I, II–IV, V, and VI, of the frontal cortex of the rat. The parameters analyzed were cortical volume, neuronal density, glial density, and neuronal soma and nucleus areas. No changes with age were found in the volume of the layers, in neuronal density (with the exception of layer I), or in the area of the neuronal soma. However, older animals showed a 10 to 20% increase in glial density, depending on the layer studied. In addition, there was an age‐related decrease in the area of the neuronal nucleus in layers II–IV, V, and VI. These results support the idea that the aging frontal cortex undergoes structural changes that may be involved in the morphological basis of memory and cognitive impairments characteristic of aging. © 1993 Wiley‐Liss, Inc.
Nucleus ambiguus of the rabbit: Cytoarchitectural subdivision and myotopical and neurotopic representations
Authors: Kitamura Seiichiro , Nagase Yoshitaka , Chen Kang , Shigenaga Yoshio
Published: February 2005

The cytoarchitectural subdivisions of the nucleus ambiguus of the rabbit and its myotopical and neurotopical representations were investigated with HRP labeling. The nucleus was subdivided into the compact cell group (CoG), the medial and lateral scattered cell groups (SGm and SGl), and the diffuse cell group (DiG). The CoG was formed by esophageal, pharyngeal constrictor, and palatal motoneurons in the rostral half of the nucleus. The SGm and SGl were located medial and lateral to the CoG, respectively, in the rostral one‐third of the nucleus. Stylopharyngeal and cricothyroid motoneurons were located in the most rostral one‐fifth of the SGm and the remaining four‐fifths, respectively, whereas the SGl was not labeled with HRP injections into the palatal, pharyngeal, esophageal, and laryngeal muscles. The DiG was formed by recurrent laryngeal motoneurons in the caudal two‐thirds of the nucleus. Neurons of origin for the glossopharngeal nerve occupied the stylopharyngeal region, with a few of them scattered in the CoG and SGl. Neurons giving rise to axons in the superior laryngeal nerve occupied the cricothyroid region, with a few of them scattered in the pharyngeal constrictor region; whereas the pharyngeal vagal branch originated from the pharyngeal constrictor and palatal regions. Neurons of the DiG, SGl, and esophageal region contributed to the infranodosal vagus nerve; esophageal fibers of the recurrent laryngeal nerve originated from the dorsal esophageal region. Laryngeal fibers of the recurrent laryngeal nerve originated from the DiG, the caudal neurons of which had axons traversing the cranial accessory root. © 1993 Wiley‐Liss, Inc.
Giant mitochondria in the seromucous secretory cells of the accessory submandibular gland of the long‐haired fruit bat, Stenonycteris lanosus
Authors: Tandler Bernard , Phillips Carleton J.
Published: February 2005

Giant mitochondria, measuring up to 6.4 μm in diameter, are present in the seromucous secretory cells of the accessory submandibular gland of the long‐haired fruit bat, Stenonycteris lanosus. These mitochondria, as well as all of the smaller ones in the same cells, contain in their matrix compartment an abundance of 33 nm threads that probably consist of protein. Some mitochondria, regardless of size, contain 5 nm helical filaments within an expanded crista. Despite their altered morphology, the enlarged mitochondria in the accessory submandibular gland of S. lanosus must be able to function normally in energy metabolism, since the secretory cells in which they are found elaborate numerous secretory granules. © 1993 Wiley‐Liss Inc.
Immune system of the spontaneously hypertensive rat: II. Morphology and function
Authors: Purcell Edwin S. , Wood Gary W. , Gattone Vincent H.
Published: February 2005

The spontaneously hypertensive rat (SHR) is a stress‐sensitive animal which exhibits moderate immune dysfunction that has been implicated in the onset of hypertension. In this study, we examined the morphology of SHR thymus and spleen and further characterized the immune deficiency using Wistar‐Kyoto (WKY) and Fisher 344 (F‐344) rats for comparison. The adult SHR thymus does not display the increase in medullary volume typically noted with aging and the volume density of the marginal zone is decreased in the spleen. In vivo tritiated‐thymidine incorporation is also decreased in the spleen of unstimulated SHR. In mixed lymphocyte reactions (MLR), the proliferative response of SHR splenocytes is significantly decreased relative to controls, WKY and F‐344. Addition of interleukin‐1 (IL‐1), interleukin‐2 (IL‐2), or indomethacin to the MLR cultures does not increase proliferation. The proliferative response to T cell receptor monoclonal antibody (mAb‐TCR) or interleukin‐2 (IL‐2) are similarly impaired in the SHR. The depressed proliferative T cell response is reversed by prolactin. It is suggested that the SHR is a valuable model for the study of immune deficiency. © 1993 Wiley‐Liss Inc.
Development of the adult endocrine pancreas during metamorphosis in the sea lamprey, Petromyzon marinus L. I. Light microscopy and autoradiography
Authors: Elliott W. M. , Youson J. H.
Published: February 2005

The results of this study were found to support the hypothesis put forth by Boenig (Z. Mikrosk‐Anat. Forsch., 17:125–184, 1929) that the caudal pancreas of adult lamprey develops from the epithelium of the extrahepatic common bile duct in that the bile duct cells were found to undergo a great proliferation during the early stages of metamorphosis, with a large number of the cells incorporating 3H‐thymidine. If the bile duct degenerated as suggested by Barrington (The Biology of Lampreys. Academic Press, London, pp. 135–169, 1972), this uptake would not be expected. The cranial pancreas was determined to develop in a similar manner to the larval islets, with formation of the islets taking place within the intestinal/diverticular epithelium. The newly formed islets would migrate into the surrounding connective tissue. During the later stages of metamorphosis a small number of cells was found to incorporate the tritiated thymidine within mature islets. © 1993 Wiley‐Liss Inc.
Striated anchoring fibrils‐anchoring plaque complexes and their relation to hemidesmosomes of myoepithelial and secretory cells in mammary glands of lactating rats
Authors: Clermont Y. , Xia L. , Turner J. D. , Hermo L.
Published: February 2005

Striated anchoring fibrils (SAF) are associated with the basement membrane underlying myoepithelial and acinar cells of mammary glands. Their proximal extremities are inserted in electron‐dense areas of the lamina densa, the anchoring plaques seen facing the hemidesmosomes of both myoepithelial and acinar cells. In the case of myoepithelial cells, the hemidesmosomes show a thick cytoplasmic plaque applied to the basal plasma membrane in which cytoplasmic filaments are inserted. Facing this plaque but on the extracellular aspect and at a short distance of 5–10 nm, there is a thin layer of electron‐dense nodular material called the subcell membrane plate, which is connected to the plasma membrane by short filamentous bridges. Between this subcell membrane plate and the anchoring plaque, there is an abundance of fine anchoring filaments crossing the lamina lucida. Such anchoring filaments are less abundant in the lamina lucida outside the hemidesmosomal areas. In the case of acinar cells, the cytoplasmic plaques of the hemidesmosomes are thin and the associated cytoplasmic filaments less conspicuous. No distinct subcell membrane plate is seen on the extracellular aspect of the plasma membrane facing the cytoplasmic plaque of the hemidesmosomes. However, in this area numerous anchoring filaments cross the lamina lucida between the plasma membrane and the SAF‐anchoring plaque complex. The abundance, in these cells, of hemidesomomes and their association with SAF‐anchoring plaque complexes seen in the basement membrane must constitute a strong attachment for both myoepithelial and acinar cells and bind them to the underlying collagen fibrils, thus preventing their detachment from the connective tissue during the contractions of myoepithelial cells during milk ejection. © 1993 Wiley‐Liss, Inc.
Inhibition of prostanoid synthesis depresses alveolar bone resorption but enhances root resorption in the rat
Authors: Lasfargues J. J. , Saffar J. L.
Published: February 2005

Tooth drift requires the deformation of the root socket and the adjustment of the other components of the attachment apparatus, namely, the periodontal ligament (PDL) and the cementum. Indomethacin (7.5 mg/kg/d), an inhibitor of prostanoid synthesis, provoked in rats a depression in the bone resorption effecting the deformation of the socket (Lasfargues and Saffar, Anat. Rec., 234:310–316, 1992). In the present paper we examined the consequence of this treatment both on the PDL and the root surface. After 3 days of treatment, when osteoclastic resorption was not yet disturbed, the root had been markedly resorbed (P<0.05) opposite the resorbing bone surface; at that time the PDL width remained in the normal range. After 7 days, i.e., when the bone resorption was depressed, the PDL was widened as the result of the ongoing root resorption. Despite the extensive root resorption, the anchorage of the PDL fibers appeared to remain effective, suggesting that it was rapidly restored. On day 14 at the time of the bone resorption recovery, cementum was deposited in the root resorption lacunae and the PDL width had returned to its control value. As early as day 3 the daily rate of dentine formation increased in the pulp area subjacent to the root resorption lacunae (P<0.01). These data demonstrate that (i) the responses of the different components of the periodontal apparatus are coordinated to allow for the maintainance of the PDL width so that when bone resorption is disturbed, root resorption compensates for it, and (ii) the odontoclasts can differentiate and resorb under prostanoid inhibition whilst osteoclastic resorption of the bone socket is inhibited. © 1993 Wiley‐Liss, Inc.
Composition and morphology of lipid droplets from oviduct epithelial cells
Authors: Henault Margaret A. , Killian Gary J.
Published: February 2005

This study was undertaken to determine the composition and morphology of lipid droplets in situ and isolated from oviductal epithelial cells and oviductal fluid. Oviductal epithelial cells were harvested enzymatically from oviducts of cows in either the luteal or the follicular stages of the ovarian cycle. Lipid droplets were isolated from cellular homogenates and characterized biochemically using thin layer chromatography. The morphology of lipid droplets in oviductal epithelial cells and in fractions isolated by ultracentrifugation from cellular homogenates was examined by electron microscopy. Lipid droplets isolated from oviduct epithelial cells varied in composition with the ovarian cycle and the oviductal region. There was more total lipid in droplets isolated from cows in the luteal than follicular phase of the ovarian cycle. Most of this difference was due to large amounts of esterified cholesterol present in the samples from luteal‐stage animals. The most esterified cholesterol was found in droplets isolated from the oviductal isthmus of luteal cows. Droplets similar in lipid composition to those isolated from epithelial cells were found in oviductal fluid. Four distinct types of lipid inclusions were evident in electron micrographs of oviductal epithelia and characterized as osmiophilic droplets, lipofuscin‐like clusters, lamellar structures, and composite bodies. All of the lipid inclusions were found in droplet isolates except for the extracted lipid portion of the composite body. The presence and diversity of oviduct epithelial lipid inclusions suggest that the oviductal epithelium may be very active in lipid metabolism, particularly cholesterol dynamics. © 1993 Wiley‐Liss, Inc.
Organization of the striatal projections from the rostral caudate nucleus to the globus pallidus, the entopeduncular nucleus, and the Pars reticulata of the substantia nigra in the cat
Authors: Hontanilla Bernardo , De Las Heras Silvano , Giménez‐Amaya José Manuel
Published: February 2005

This study explores the organization of the striatal projections from the rostral caudate nucleus to the output nuclei of the basal ganglia in the cat. Tracer deposits were stereotaxically injected in different dorsoventral, mediolateral, and rostrocaudal sectors of the head of the caudate nucleus using horseradish peroxidase (HRP) conjugated with wheat germ agglutinin (HRP‐WGA) either alone or mixed with free HRP. After the injections, a detailed analysis of the terminal labeling was carried out within the globus pallidus (GP), the entopeduncular nucleus (Ep), and the substantia nigra (SN) pars reticulata (SNR). Our findings illustrate how different dorsoventral, mediolateral, and rostrocaudal parts of the rostral caudate nucleus project primarily to similarly positioned but spatially segregated parts of GP. The striatoentopeduncular pathway was also organized topographically, but there was overlapping by projections from different parts of the rostral caudate nucleus. Areas of topographical segregation and zones of overlap were detected in the organization of the striatal projections from the rostral caudate nucleus to SNR. These results raise the possibility of distinct striatal actions upon different sectors of the output nuclei of the basal ganglia and, indirectly, upon their targets in the thalamus and brainstem. © 1994 Wiley‐Liss, Inc.
Neonatal development of the diaphragm of the horse, Equus caballus
Authors: Cobb Matthew A. , Schutt William A. , Petrie Jacquelyn L. , Hermanson John W.
Published: February 2005

The diaphragm of neonatal horses is significantly different from the diaphragm of adult horses in terms of histochemical fiber type composition, myosin heavy chain isoform, and native myosin isoform composition. There is a significant increase in the percentage of type I fibers present in the diaphragm with increasing age from birth through about seven months postnatal age. A possible lack of postural tone in the hiatal region of the neonatal diaphragm is suggested to account for increased incidence of vomiting or aspiration pneumonia in younger horses. The isoform data lead to rejection of the hypothesis that the diaphragm of the horse should, as an ungulate, be relatively precocial in its rate of maturation relative to other non‐ungulate mammals that have been studied. © 1994 Wiley‐Liss, Inc.
Translocation of enamel proteins from inner enamel epithelia to odontoblasts during mouse tooth development
Authors: Nakamura Masanori , Bringas Pablo , Nanci Antonio , Zeichner‐David Margarita , Ashdown Brian , Slavkin Harold C.
Published: February 2005

The developmental problem of how dental epithelia and/or dental papilla ectomesenchyme induce and/or up‐ or down‐regulate tooth formation are as yet unresolved issues. We have desinged studies to map the synthesis and fate pathways of secreted amelogenin proteins from Kallenbach differentiation zones II–IV during in vivo and in vitro mouse mandibular first molar tooth development (M1). Tooth organs from cap, bell, and crown stages were processed for reverse transcriptase/polymerase chain reaction (RT‐PCR) and high resolution Protein A immunocytochemistry using anti‐amelogenin and anti‐peptide antibodies. Cap stage M1 were cultured for periods ranging from 10–21 days in vitro using either serumless, or 15% fetal calf sera‐supplemented, chemically‐defined medium. Amelogenin transcripts are expressed in the mouse embryonic molar from E15 through early postnatal development. Amelogenin antigens were first detected in Kallenbach's differentiation zone II. Amelogenin proteins secreted from preameloblasts were identified along cell processes and cell surfaces of odontoblasts adjacent to forming mantle dentine extracellular matrix (ECM) prior to biomineralization. Amelogenin proteins were restricted to forming endocytotic vesicles, clathrin‐coated vesicles, and lysozomes within odontoblasts. At later stages (e.g. 2 days postnatal development), enamel proteins were not identified in odontoblasts or predentine matrix following mineralization. Comparable observations for stages of development were noted for in vitro cultured tooth explants. Preameloblasts synthesize and secrete amelogenin proteins which bind to odontoblast cell surfaces possibly through the process of receptor‐mediated endocytosis. We conclude that amelogenin proteins secreted from preameloblasts, prior to the initiation of biomineralization, were translocated to odontoblasts to serve as yet unknown biological functions. © 1994 Wiley‐Liss, Inc.
Ultrastructural studies and immunolocalization of enamel proteins in rodent secretory stage ameloblasts processed by various cryofixation methods
Authors: Nanci A. , Kawaguchi H. , Kogaya Y.
Published: February 2005

Background: Cryofixation rapidly immobilizes cell and tissue components in their native state, thereby resulting in an ultrastructural preservation very close to the living situation. We have applied this approach to examine the morphology of secretory stage ameloblasts and the distribution of enamel proteins in these cells.

Methods: Molar and incisor tooth germs from newborn mice and/or rats were quickly dissected and divided into segments. The segments were then rapidly frozen using slam, plunge or pressure freezing, freeze‐substituted and embedded in Epon. In addition, incisors from older rats were chemically fixed by vascular perfusion and also dehydrated by freeze‐substitution.

Results: Well‐preserved ameloblasts were obtained with all four tissue processing methods. However, slam freezing often showed mechanical damage to the ameloblasts, particularly at the level of the distal portion of Tomes' processes which appeared severed or distorted. Plunging into liquid nitrogen‐cooled liquid propane resulted in comparatively less tissue distortion. High pressure freezing gave a relatively higher yield of well‐preserved specimens, although displacement of organelles in ameloblasts was sometimes observed, probably resulting from hydrostatic pressure. Minimal ice crystal and mechanical damage was observed in chemically fixed tooth samples processed by freeze‐substitution since such specimens are cryoprotected and their examination is not restricted to a surface layer. With all of the above cryopreparation methods, the ultrastructure of well preserved ameloblasts was, in general, similar to that obtained following conventional chemical fixation, and immunocytochemistry with an anti‐amelogenin antibody indicated no profound differences in the distribution of enamel proteins.

Conclusions: These results indicate that, despite some limitations, it is possible to adequately cryofix tooth organs while preserving the architecture of ameloblasts and permitting immunolocalization of enamel proteins. Furthermore, they confirm the general morphology of secretory stage ameloblasts as currently derived from conventional chemical tissue processing. © 1994 Wiley‐Liss, Inc.
Organization of tracheal epithelium in the cartilaginous portion of adult rabbit and its persistence in organ culture
Authors: Johnson Russell A. , Stauber Ziva , Robert Hilfer S. , Kelsen Steven G.
Published: February 2005

Background: The rabbit trachea provides a model system to test the physiological responses of the airways to various agents. Since three‐dimensional organization may affect responses of an organ, an organ culture model was established in serum free medium.

Methods: Tracheas were fixed in situ, at steps in the preparation of organ cultures, and after one day to three weeks in organ culture. Samples were examined by light microscopy and scanning and transmission electron microscopy for surface morphology, distribution of cell types, and characteristics of the epithelial cell layer.

Results: The normal tracheal mucosa was discovered to consist of extensive circumferential folds in the cartilaginous portion, which were enhanced upon isolation of the trachea from the animal. The folds consisted principally of differences in epithelial cell height rather than folding of the lamina propria. Enhancement of folding upon removal of the trachea coincided with increased secretion by Clara and possibly mucous cells. In organ culture, epithelial cell height initially increased, producing tall folds and cell types were retained in normal proportions. After prolonged culture, cilia were lost but glandular secretion continued.

Conclusions: Changes in the arrangement of basal cells and secretory activity in isolated trachea and in culture may give insight into the functional significance of the epithelial folds. © 1994 Wiley‐Liss, Inc.
Ultrastructure and development of a thick basement membrane‐like layer in the anchoring villi of macaque placentas
Authors: King Barry F. , Blankenship Thomas N.
Published: February 2005

Background: Anchoring villi and cytotrophoblastic cell columns are important structural components involved in placental morphogenesis. We have previously described the presence of an unusual basement membrane‐like layer (BMLL) that separates these placental compartments. The purpose of the present study was to identify developmental changes in the ultrastructure of the BMLL and to assess its changes in extracellular matrix composition over the course of gestation.

Methods: Conventional techniques were used to examine macaque placental tissue by transmission electron microscopy. Standard immunoperoxidase methods were used to identify type IV collagen, laminin and fibronectin in paraffin sections.

Results: Until day 35 of gestation the BMLL was 70–100 nm thick and appeared similar to basement membranes seen in other regions of the villus, although it usually lacked a lamina lucida along the surface adjacent to the cytotrophoblast cells. Immunohistochemistry revealed the presence of laminin and type IV collagen in the BMLL. By 53 days of gestation the BMLL had hypertrophied at the junction of the anchoring villus and cell column, measuring 2,000–5,000 nm in thickness. The BMLL retained immunoreactivity for laminin and type IV collagen. Ultrastructural examination revealed the presence of a new component in the form of 10 nm microfibrils. By 89 days of gestation the BMLL was not reactive for laminin or type IV collagen but otherwise maintained the structural organization seen at 53 days. No additional changes were observed in the BMLL during late pregnancy.

Conclusions: The BMLL is a distinct extracellular matrix region that separates the distal aspect of the anchoring villus from the proximal portion of the cell columns. Evidence indicates that adjacent cytotrophoblast plays a prominent role in the production of the BMLL. The BMLL may serve to organize this complex tissue by separating fetal mesenchyme from cytotrophoblast cells that are proliferating, differentiating, and migrating. Modifications to the composition of the BMLL may indicate changes in the role this matrix plays in the development of the placenta. © 1994 Wiley‐Liss, Inc.
Extractions reveal specific argentophilic proteins in rat and bull sperm heads
Authors: Yagi Ahmed , Paranko Jorma
Published: February 2005

Background: Silver‐stainability (argentophilia) of cytoplastmic structures occurring in spermatids have been localized into the organizing perinuclear theca, but the biochemical nature and structural associations of these proteins with the cytoskeletal and membranous elements are unresolved and, therefore, were the aim of the present study.

Methods: Light and electron microscopic analysis of the silver‐stainability in the rat spermatids and spermatozoa was carried out in the intact testis tissue and epididymal spermatozoa and after their chemical and mechanical extraction. Correlation of argentophilia with specific proteins of rat and bovine spermatids and spermatozoa was investigated using a recently developed technique for silver nitrate staining of proteins on nitro‐cellulose.

Results: Sequential formation of the silver‐stainable domains seemed to proceed from the argentophilic acrosomal ring. Various extractions indicated that argentophilia in the spermatids and spermatozoa was mainly associated with the perinuclear theca and to some extent to the plasma membrane. Hyamine‐soluble extract from spermatozoa of rat and bull revealed only a single argentophilic protein of 130 kDa. Hyamine and SDS‐soluble extracts of rat testis tissue contained an additional group of argentophilic polypeptides of lower molecular weight (115, 94, 36, 23, and 21 kDa).

Conclusions: Reduction in the number of argentophilic proteins appears to be involved in a series of changes in the cyto‐architecture of developing spermatids. Tentative cytoskeletal nature of argentophilic proteins remains to be identified. Nevertheless, they may have important physical relations with the higher‐order organization of the sperm head cytoskeleton and overlying membranes. © 1994 Wiley‐Liss, Inc.
Neuroepithelial bodies in the lung of Basiliscus vittatus (Reptilia, Iguanidae)
Authors: Steen Peter van Den , van Lommel Alfons , Lauweryns Joseph M.
Published: February 2005

Background: Neuro‐epithelial bodies (NEB) are corpuscles of currently equivocal function which are present in the lungs of vertebrates. Comparative studies may help to elucidate their role.

Methods: The NEB of Basiliscus vittatus (Reptilia, Iguanidae), a terrestrial lower vertebrate able to dive, are for the first time examined by electron microscopy, immunocytochemistry, and for argyrophilia.

Results: Most NEB contain both immunoreactive calcitonin and serotonin but are not labelled with argyrophilia or immunocytochemistry against calcitonin gene‐related peptide (CGRP), protein gene product 9.5 (PGP 9.5), or the Leu‐7 epitope (Leu‐7). Therefore, in NEB of this species, the transcription of the calcitonin/CGRP gene exclusively favors the expression of calcitonin and this is in contrast to the intrapulmonary small neurons. Also, a physiologic difference is expected in the metabolism of ubiquitin in NEB of B. vittatus vs. mammalian NEB and neurons. In addition, the NEB cells are always covered by at least a thin cytoplasmic extension of a neighbouring cell, indicating that luminal contact is not required. Stronger still, it appears that in some lower vertebrates contact to the airspace is avoided. Finally, we provide ultrastructural evidence for the basket‐like innervation of NEB in some reptiles. This way of innervation possibly represents an evolutionarily different concept for interaction between NEB corpuscular cells and nerve fibers.

Conclusions: Beyond the confirmation that morphology, content of biologically active substances such as serotonin and calcitonin, and innervation are evolutionary well preserved features of NEB, the results reveal some intriguing features of B. vittatus NEB: strict separation of calcitonin and CGRP, reduced need for the de‐ubiquitinating enzyme PGP 9.5, lack of luminal contact, and the basket‐like innervation. The latter two properties possibly refer to a mechanoreceptor function of NEB in this species. © 1994 Wiley‐Liss, Inc.
Conjoined twin piglets with duplicated cranial and caudal axes
Authors: McManus Cheryl A. , Partlow Gary D. , Fisher Kenneth R. S.
Published: February 2005

Background: Twins with doubliong of the cranial and crudal poles, yet having a single thorax, are rare.

Methods: One set of diprosopus, dipygus porcine conjoined twins was studied.

Results: In addition to the conjoining anomaly, these twins also exhibited ambiguous internal reproductive features. The twins had two snouts, three eyes, a single thorax, and were duplicated from the umbilicus caudally. Radiography indicated a single vertebral column in the cervical region. The vertebral columns were separate caudally from this point. There was a total of six limbs—one pair of forelimbs and two pairs of hindlimbs. Many medial structures failed to develop in these twins. Medial cranial nerves V–XII were absent or displaced although apprarently normal laterally. The medial palates were present but shortened, whereas the medial mandibular rami had folded back on themselves rostrally to form a midline mass between the two chins. Each twin had only one lateral kidney and one lateral tests. Medial scrotal sacs were present but devoid of a testis. There was a midline, “uterine”‐like structure which crossed between the twins. However, histological analysis of this structure revealed it to be dysplastic testicular tissue.

Conclusions: The relationship between the abnormal reproductive features in these twins and the conjoining is unclear. The anatomy of these twins, in addition to the literature reviewed, illustrates the internal anatomical heterogeneity of grossly similar conjoined twins. A review of the literature also suggests that conjoined twinning may be more common in swine than was previously suspected. © 1994 Wiley‐Liss, Inc.