bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between genital ridge formation and settlement site of primordial germ cells in chick embryos
Authors: Ukeshima Atsumi , Kudo Masayuki , Fujimoto Toyoaki
Published: February 2005

Chick embyros from stage 15 to stage 18, which is the most frequent extravasation period, were investigated by means of serial sections and light microscopy in order to learn the detailed relationship between the settlement sites of the primordial germ cells (PGCs) and the forming genital ridge. PGCs circulating in the vascular system came out of the small vessels in the splanchnopleure posterior to the vitelline artery. This PGC extravasation was limited to an area about 1.2 mm caudal to the vitelline artery. After the extravasation, the PGCs entered the neighboring thickened coelomic epithelium of the splanchnopleure. This thickened epithelium, which had incorporated the PGCs, changed the location toward the future gonadal site with the advance of development. At stage 16, the thickened portion of the epithelium was located in the splanchnopleure; then it moved toward the somatopleure via the coelomic angle; finally, at stage 18, this epithelium occupied the region between coelomic angle and the mesonephros which corresponded to the future genital ridge. This means that the thickened epithelium of the splanchnopleure which initially incorporated the PGCs becomes the superficial epithelium of the genital ridge in more advanced stages. The thickened portion of the epithelium of the splanchnopleure at stage 16 is thought to be the definitive gonadal anlage.
Hemopoietic cells in the liver and spleen of the embryonic and early postnatal mouse: A karyometrical observation
Authors: Sasaki Kazunobu , Matsumura George
Published: February 2005

Hemopoietic cells in the liver and spleen of embryonal and early neonatal mice were karyometrically examined by light microscopy. Hepatic hemopoiesis started at 11 days gestation, and proerythroblasts and less differentiated cells with nuclei larger than 7 μm in diameter, appeared in the primitive hepatic cords. After 12 days, the liver contained a number of mature erythroblasts. The immature large hemopoietic cells disappeared from the liver at 16 days gestation. Splenic hemopoiesis began at 16 days gestation. Hemopoietic cells with nuclei measuring larger in diameter than 8 μm appeared in the splenic cords, and the immature cells could be seen even at 2 days after birth.

Development of embryonic hemopoiesis from the liver to the spleen is discussed in relation to yolk sac and bone marrow hemopoiesis.
Electron microscopic cytochemical localization of a basolateral calcium adenosine triphosphatase in vitamin D replete chick enterocytes
Authors: Davis Walter L. , Jones Ruth Gwendolyn , Farmer Gene R. , Matthews James L. , Martin James H. , Bridges George
Published: February 2005

A cytochemical technique for the electron microscopic localization of calcium adenosine triphosphatase (Ca‐ATPase) was utilized to localize this enzyme in the enterocytes of rachitic and vitamin D‐replete chicks. In animals treated with cholecalciferol (CC, vitamin D3), an electron‐dense reaction product was located along the basolateral membranes of the absorptive cells within 72 hr after injection. Similarly, a reaction product was identified in association with the basolateral membranes within 24 hr after injection of 1,25‐dihydroxycholecalciferol, the active metabolite of vitamin D. A microvillar reaction product was not seen in either of these two groups. Electron‐dense reaction products were also seen in association with mitochondria and scattered throughout the cytoplasm of these enterocytes. The Ca‐ATPase reaction product was dependent upon the presence of medium calcium and substrate (ATP), was inhibited by vanadate, and was heat labile. In the rachitic animals, a reaction product indicative of Ca‐ATPase activity was not seen in association with either the basolateral membranes or the mitochondria. These data appear to indicate that an energy‐requiring calcium‐activated membrane pump plays a role in the flux of calcium across the enterocytes of the small intestine.
Role of muscle neurotization in the reinnervation of murine muscle grafts
Authors: Klueber Kathleen M.
Published: February 2005

Although the reinnervation of muscle grafts has been demonstrated, the question remains as to the source of neurons reinnervating the graft. A muscle graft could be reinnervated by its original neurons (neural neurotization) or by sprouting of axons which supply the intact myofibers of surrounding muscles (muscle neurotization). The objective of this study was to evaluate the role of muscle neurotization in the reinnervation process using both horseradish peroxidase and fluorescent tracers. Observations from 20 muscle grafts indicate that the neurons reinnervating the grafts are from the original motor neuron pool. Thus muscle neurotization may not occur during the reinnervation process.
Phorbol ester stimulates macrophage invasion of fibrin matrices
Authors: Castellucci Mario , Montesano Roberto
Published: February 2005

Macrophages migrate through a fibrin‐rich extracellular matrix in chronic inflammation, wound healing, and other pathophysiological processes. To investigate the factors that might influence the ability of mononuclear phagocytes to invade fibrin matrices, we cultured macrophage‐like P388D1 cells as well as resident and thioglycollate‐elicited mouse peritoneal macrophages on three‐dimensional fibrin gels, and we examined the effect of agents known to stimulate a variety of macrophage functions, including the production of fibrinolytic enzymes. Cells grown on fibrin gels under control conditions, as well as cells treated with either bacterial lipopolysaccharide or concanavalin A, remained confined to the gel surface. In contrast, the tumor promoter 4β‐phorbol 12‐myristate 13‐acetate (PMA) induced both P388D1 cells and peritoneal macrophages to invade the underlying fibrin matrix. The invasive behavior of PMA‐treated P388D1 cells was not affected by protease inhibitors of various specificities. These results demonstrate that certain exogenous signals can profoundly modify the ability of macrophages to migrate through fibrin matrices.
Structural changes in nuclear chromatin in rat pituitary after chronic stress of low intensity
Authors: Komitowski Dymitr , Muto Shuhei , Weiss Jürgen , Schmitt Bertold , Taylor George T.
Published: February 2005

Acute, intense sources of “psychogenic” stress clearly modify the structure and function of the hypophysis, and there are concomitant changes in many peripheral physiological systems. Less dramatic sources of stress yield more equivocal results. An experiment is reported in which nuclear morphology of adenohypophyseal cells from 49 male rats exposed to a chronic, low‐intensity stressor was examined both by conventional histological and computer‐assisted‐image‐processing methods. The hypothesis tested was that an unequivocal pattern of morphological changes in the nucleus and nuclear chromatin would be revealed by image processing. Rats were killed after living for a year in a relatively low‐stress environment, “crowded” in groups of five animals per cage. The control condition was a minimal stress environment of two rats per cage. Results suggested few signs of pathology from peripheral measures of hypophyseal activity, and direct light microscopic examination of the gland revealed no differences between the two groups. Analysis of computer‐enhanced images of the pars distalis nuclei from the adenohypophysis, on the other hand, generated findings that were statistically and biologically significant. Nuclear size increased in the stress condition, the number of chromatin and area occupied by the particles increased, and the position of chromatin shifted toward the periphery of the nucleus. Perhaps more important, optical density analysis indicated that chromatin was less tightly packed in the experimental animals. Implications are that chronic, low‐intensity stress modulates nuclear structural changes from a dormant to an active state that portend changes in the peripheral systems influenced by the hypophysis.
Pericardium of rodents: Pores connect the pericardial and pleural cavities
Authors: Nakatani Toshio , Shinohara Harumichi , Fukuo Yoshifumi , Morisawa Satoshi , Matsuda Takeshi
Published: February 2005

Numerous circular fenestrations or pores were present in the pericardium of the rat, golden hamster, and mouse. The pericardial pores were most numerous in the mouse. They were usually less than 50μm in diameter and situated in a meshwork formed by thick, wavy bundles of collagen fibers and thin, straight, elastic fibers. These pores directly connected the pericardial and pleural cavities and indirectly connected the right and left pleural cavities; i.e., the pericardial cavity in the rodents is not independent from but intercommunicates with the adjacent pleural cavities.

There were many aggregates of free cells or milky spots in the pericardium. They principally consisted of lymphocytes, macrophages, and mast cells and were directly exposed to the pericardial cavity.
Expression of cellular glycoconjugates in transfilter‐induced metanephric mesenchyme
Authors: Laitinen Liisa , Virtanen Ismo , Saxén Lauri , Lehtonen Eero
Published: February 2005

Expression of glycoconjugates during transfilter‐induced differentiation of metanephric mesenchyme was studied by using fluorochrome‐ and peroxidase‐coupled lectins. All cells in the uninduced metanephric mesenchyme expressed mannose, β‐D‐galactose (β‐Gal), N‐acetylglucosamine (GlucNAc), and terminal sialic acids. Additionally, solitary cells showed terminal α‐D‐galactose (α‐Gal) typical of mouse endothelial cells. During culture, undifferentiated mesenchymal cells seemed to disappear from induced explants, and many of the stromal cells between the evolving tubules presented terminal α‐Gal residues. Similar positivity could be revealed in monolayer cultures of induced mesenchymes. A number of tubules in induced explants displayed α‐L‐fucosyl (Fuc) residues, characteristic of mature proximal tubules. Some terminal Ga1NAc residues, recognized only by Dolichos biflorus agglutinin, emerged in a few tubular cells after prolonged culture. The early tubules and glomerular bodies displayed a basement membrane presenting both terminal Gal‐(β1‐‐3)‐Ga1NAc and Ga1NAc residues. These positivities disappeared later from many tubular structures and glomerular bodies but persisted in tubules expressing proximal tubular differentiation. The glomerular bodies displayed only one cell type, reminiscent of maturing podocytes, presenting terminal Ga1‐(β1‐‐3)‐Ga1NAc and Ga1NAc residues. Later these saccaride residues became covered by sialylation, as they could then be revealed only after treatment with neuraminidase.

The results indicate that the segment‐specific expression of saccharide residues during differentiation of nephron in vitro resembles the sequence seen in vivo. This study also suggests that the basement membranes surrounding the nephron show a stepwise, segment‐specific maturation. Despite the presence of endothelial cells in the metanephric explants, only avascular glomeruli evolved in this differentiation model.
Innervation of muscle receptors in the cross‐reinnervated soleus muscle of the cat
Authors: Ip M. C. , Luff A. R. , Proske U.
Published: February 2005

It has recently been reported (Gregory et al., J. Physiol., 331:367–383, 1982) that cutting a muscle nerve and letting it grow back into the muscle or cross‐uniting the muscle with a foreign nerve results in major disruption of the normal response patterns of muscle spindles and tendon organs. Here we report observations on the structure of muscle receptors in cross‐reinnervated and self‐reinnervated soleus muscles in an attempt to detect abnormalities that might account for their disturbed function. Eight soleus muscles were reinnervated with the extensor digitorum longus nerve for periods up to 449 days and two were self‐reinnervated. Following the physiological investigation, the muscle was fixed and stained according to the method of Barker and Ip (J. Physiol., 69:73P‐74P, 1963). Spindles and tendon organs were teased from the muscle and photographed. In one cross‐reinnervated muscle an attempt was made to isolate all receptors. About two‐thirds of the normal number of spindles and tendon organs were found. Three categories of receptor were identified: normal, abnormal, and those having no visible nerve endings. There appeared to be little difference in degree of abnormality of receptors in self‐ and cross‐reinnervated muscles. Of the 180 spindles, 3% were normal, 43% had no visible endings, and 54% had abnormal endings. Of 80 tendon organs, 38% were normally innervated, 33% were without visible innervation, and 29% had abnormal endings. We conclude that following long‐term cross‐reinnervation and self‐reinnervation of soleus there is extensive disruption of the normal innervation pattern of both spindles and tendon organs which could account for their functional abnormalities.
Ultrastructure of the main excretory duct epithelia of the rat parotid and submandibular glands with a review of the literature
Authors: Sato Atsuko , Miyoshi Sakuichiro
Published: February 2005

The fine structure of the main excretory duct (MED) epithelia of the rat parotid and submandibular glands was investigated by scanning and transmission electron microscopy. The structure of these two MED epithelia was compared. Five principal cell types were observed in the MED epithelium of the parotid gland‐cuboidal, basal, light (types I and II), dark, and tuft

This cell has been given different names such as “peculial cell” (Järvi and Keyrilainen, 1955), “brush cell” (Rhodin and Dalhamn, 1956), “tuft cell” (Järvi, 1962), “multivesicular cell” (Silva, 1966), “undifferentiated cell” (Johnson and Young, 1968), “s‐cell” (Ferguson, 1969), “agranular light cell” (Riches, 1972), “caveolated cell” (Nabeyama and Leblond, 1974), and “fibrillo vesicular cell” (Wattel and Geuze, 1978). The term “tuft cell” has been used throughout the present study.

cells. The cuboidal cells, which were stratified in two or three layers, were the most numerous. Basal cells were situated adjacent to the basal lamina of the epithelium. The type I light cells had well‐developed basal plasma membrane infoldings. The type II light cells had poorly developed basal plasma membrane infoldings. The dark and tuft cells resembled those of the MED epithelium of the rat submandibular gland.

Four principal cell types were observed in the MED epithelium of the submandibular gland—light cells (types I and 11), dark, tuft, and basal cells. The two types of light cells were the most numerous. Dark cells with regular and dense microvilli were relatively narrow in shape and had complicated basal plasma membrane infoldings. There were numerous vesicles or channel—like vesicles in their apical cytoplasm. Tuft cells were characterized by prominent microvilli, many vesicles of various sizes in the apical cytoplasm, and no basal infoldings.

Peroxisomes were present in the MED epithelia of the rat parotid and submandib‐
ular glands, especially in light and cuboidal cells.
Nuclear shaping in spermatids of the Thai leaf frog Megophrys montana
Authors: Asa Cheryl S. , Phillips David M.
Published: February 2005

Transmission electron microscopy of Thai leaf frog testis revealed a unique pattern of spermatid nuclear morphogenesis. Chromatin condenses into a continuous cylindrical coil within a roughly spherical nucleus. Later the nuclear membrane conforms to the contours of the uncoiling nuclear contents. In the mature sperm, the long, tapering nuclesus is helically shaped. This developmental sequence occurs in the absence of a microtubular manchette, raising questions about the role of this structure in nuclear shaping in spermatozoa of other species.
Periapical innervation of the ferret canine and the local retrograde neural changes after pulpectomy
Authors: Holland G. R.
Published: February 2005

The amputation of the dental pulp severs a population of axons that are predominantly in the Aδ and C fiber size range and are principally involved in nociception. Local periapical neuromas, if they are formed after pulpectomy, may be the sites of spontaneous nervous activity that may, in some circumstances, be involved in the genesis of chronic pain. The periapical tissues from the mandibular canines of four ferrets were examined 3 months after pulpectomies. Silver‐stained paraffin sections were examined in three dimensions at the light microscope level. Ultrathin sections were examined at the electron microscope level. Compared with contralateral and independent controls, the principal changes were the loss of the periodontal plexus around the root apex, the extension of damage well below the apical foramen, and the persistance of inflammation 12 weeks postoperatively. While a somewhat disorderly mass of nerve fibers develops subapically, the arrangement has only some of the features usually associated with neuromas.
Regional differentiation in the stomach of the green anole
Authors: Lehman Sharon , Smith Allen A.
Published: February 2005

The stomach of Anolis carolinensis (Reptilia: Iguanidae) has four histologically and histochemically distinct regions. The gastroesophageal junction has an acidic surface mucin and no glands. The cardia has an acidic surface mucin and mucous glands. This acidic mucin appears to contain neither sulfates nor sialic acid. The fundus has a neutral surface mucin and mucoserous glands. The pylorus has a neutral surface mucin and mucous glands.
Ultrastructural cytochemistry of trout arterial fibrils as elastic components
Authors: Isokawa Keitaro , Takagi Minoru , Toda Yoshihisa
Published: February 2005

The trout arterial wall contains numerous extracellular fibrils that are presumed to be elastic. However, the cytochemical properties of the arterial fibrils have not been studied. Thus, we have ultrastructurally and cytochemically examined these fibrils, utilizing routine uranyl acetate and lead (UA‐Pb) double staining, the tannic acid (pH 7.0)‐uranyl acetate (TA‐UA) method as an electrondense staining for elastin, and Thiéry's periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) method to localize vicinal glycol‐containing complex carbohydrates. The arterial fibrils, about 23 nm in thickness, were interwoven at random but frequently showed the circular alignment to the long axis of the aorta. Occasionally they appeared to coalesce side by side, and the coalesced portion tended to lose its affinity for UA‐Pb stains. The TA‐UA method stained the fibrils moderately to intensely and stained the coalesced parts of the fibrils more intensely. All of those TA‐UA positive fibrils were completely removed after elastase en bloc digestion. The PA‐TCH‐SP method did not stain the arterial fibrils but stained another kind of much thinner interfibrillar filamentous structure. These results suggest that the fibrils in the wall of trout ventral aorta are elastin in nature and do not contain vicinal glycols, although the fibrils usually exist in a fibrillar form, which is unlike mammalian amorphous elastin.
Ultrastructural and immunocytochemical studies of prolactin‐secreting cells (PRL cells) in the anterior pituitary gland of the female musk shrew (Suncus murinus L.)
Authors: Ishibashi Toshiko , Shiino Masataka
Published: February 2005

Prolactin‐secreting cells (PRL cells) in the anterior pituitary gland of the female musk shrew were identified by the protein A—gold procedure combined with electron microscopy. Their secretory granules were spherical, and showed variuos sizes ranging in diameter from 100 nm to 800 nm according to the difference in physiological conditions of the animals.

In pregnant and lactating animals, the PRL cells exhibited morphologically active features, i.e., a large prominent Golgi apparatus and a well‐developed rough endoplasmic reticulum (RER) consisting of densely packed parallel lamellae. In pregnant and estrogen‐treated animals, the secretory granules of PRL cells significantly increased in size as compared with those of virgin animals.

The most remarkable ultrastructural change observed in PRL cells of pregnant, lactating, and estrogen‐treated female musk shrews was the occurrence of “intracisternal” granules. They were small and spherical, and were located without limiting membranes inside the dilated cisternae of the RER. Intracisternal granules, as well as ordinary secretory granules, were found to be immunoreactive for PRL by the protein A—gold procedure. These results suggest that PRL cells of the female musk shrew may possibly utilize a “bypass” route to form hormone‐containing granules under highly activated cellular conditions.
Fine structural peculiarities of the pectoral fin dermoskeleton of two Brachiopterygii, Polypterus senegalus and Calamoichthys calabaricus (Pisces, Osteichthyes)
Authors: Géraudie Jacqueline
Published: February 2005

The features of the dermal skeleton of the pectoral fins of two Brachiopterygii, Polyterus senegalus and Calamoichthys calabaricus, have been studied by light and electrom microscopy. The components studied are the ganoine covered lepidotrichia segments and the distally located actinotrichia, the features of which are similar to those in teleosts. An irregular patch of ganoine susceptible to erosion by vascular canals lies on top of the cellular bone of the upper surface of the segment. It is separated from the stratified epidermis by an organic intermediate layer in place of the dermoepidermal interface. This layer is interpretated as “antislip pad” or elastic glue anchoring the epidermis on the hypermineralized ganoine. Such components are also observed in ganoid scales, although embryological data fail to support that lepidotrichial segments are modified scales. The lack of dentin in lepidotrichia emphasizes the tendency during evolution toward the reduction of some dermoskeletal components and exemplifies ganoine deposition directly on top of the bones as in holostei scale. The participation of neural crest cells in development of the dermal skeleton is discussed by way of the repartition of the odontods within the pectoral fin.
Distribution of esterase activity at the level of the epithelium of the diffusely infiltrated area (DIA) and of the cloaca in the Gallus domesticus: An ultrastructural study
Authors: Dolfi A. , Giannessi F. , Bianchi F. , Lupetti M.
Published: February 2005

Esterase activity studies on the areas of lymphoid infiltration in the bursa of Fabricius (diffusely infiltrated area) and the dorsal wall of the cloaca showed that the epithelial cells exhibit varying degree of diffuse esterase activity; it was possible to demonstrate the presence of spot‐like esterase positivity in star‐shaped cells in the epithelium itself. These cells can be found at various levels from the proximal to the distal region and have also been observed in the connective tissue of the tunica propria; as a result, the hypothesis has been advanced that they are connective tissue.
Stochastio morphological model of the rat lung
Authors: Koblinger László , Hofmann Werner
Published: February 2005

The laboratory rat is often used as a human surrogate in aerosol inhalation studies. Here we present a new stochastic model for the rat lung analogous to that for the human lung. Morphometric data on the tracheobronchial geometry of the rat lung provided by the Lovelace Inhalation Toxicology Research Institute were analyzed. The results of this statistical analysis reveal significant differences in diameters and branching angles between major and minor daughter tubes starting from the same bifurcation. As a consequence of the more monopodial airway branching in the rat lung compared to the more dichotomous structure of the human lung, we recommend classifying the rat lung airways by their diameters and not by generation numbers. The distributions of the gemetric airway parameters and the correlations among them will be used for Monte Carlo deposition calculations.
Innervation and gap junction formation in the myometrium of pregnant little brown bats, Myotis lucifugus
Authors: Buchanan G. D. , Garfielde R. E. , Younglai E. V.
Published: February 2005

Pregant Myotis lucifugus were captured in mist nets set outside a large maternity colony and, in most cases, were examined 12–15 hours later. Anterior and posterior halves of uteri were pinned to dental wax and either incubated in glyoxylic acid to produce adrenergic nerve fluorescence, or fixed in buffered glutaraldehyde for electron microscopy. Blood was collected for radioimmunoassay of plasma progesterone. We found no evidence of decreased nerve fluorescence even in late pregancy when plasma progesterone levels were 10–20 times preovulatory values. Ultrastructtural examination also showed no evidence of damage to, or destruction of, nerves in the myometrium. However, we did find gap junctions between myometrial muscle cells during the periparturient period in both normal and aborting bats. Gap junctions began to form several days before term, increased in number until parturition, then decreased dramatically within a day or two thereafter. The percentage of muscle cell plasma membrane involved in gap junction formation was closely correlated with plasma progesterone levels, although whether this is causal or coincidental is not certain.

These data do not agree with the conclusion drawn from observations in other mammals that a disappearance of adrenergic nerves from the myometrium is associated with the initiation of parturition, or that gap junction formation is associated with changes in nerve function. They do, however, lend further support to the hypothesis that there is neurogenic control of myometrial contractility in M. lucifugus, uteri at term.
Effects of mevinolin, an inhibitor of cholesterol synthesis, on the morphological and functional responses of rat adrenal zona fasciculata to a prolonged treatment with 4‐aminopyrazolo‐pyrimidine
Authors: Mazzocchi Giuseppina , Rebuffat Piera , Belloni Anna S. , Gottardo Giuseppe , Meneghelli Virgilio , Nussdorfer Gastone G.
Published: February 2005

Rat adrenocortical cells are almost completely dependent upon the continuous supply of cholesterol derived from serum lipoproteins. However, a prolonged (5‐day) administration of 4‐aminopyrazolo‐pyrimidine (4‐APP), a potent hypocholesterolaemic drug, though provoking a notable decrease in the intra‐adrenal concentration of esterified and free cholesterol, did not significantly affect basal plasma level of corticosterone. Morphometry showed a conspicuous hypertrophy of zona fasciculata cells, coupled with a striking proliferation of smooth endoplasmic reticulum (SER) and peroxisomes and with a profound lipid‐droplet depletion. The secretory response of zona fasciculata cells to ACTH was still present, but reduced by half with respect to control rats. The simultaneous administration of mevinolin, an inhibitor of cholesterol synthesis, to 4‐APP‐treated rats caused an additional drop in the intracellular content of free cholesterol and notably lowered basal plasma corticosterone concentration. Mevinolin magnified the 4‐APP‐induced zona fasciculata cell hypertrophy, as well as SER and peroxisome proliferation. The secretory response to ACTH was completely suppressed. These data are compatible with the view that the morphological changes, which rat zona fasciculata cells undergo during prolonged hypocholesterolaemia, are the expression of the activation of the endogenous cholesterol synthesis. This compensatory response, enabling zona fasciculata cells to maintain a normal basal rate of hormonal output and to respond (though less efficiently) to their main physiological stimulus, seems to be completely independent of any activation of the hypothalamo‐hyphophyseal axis, since dexamethasone/ACTH treated rats were used. The hypothesis is advanced that the mechanism underlying this response may involve the decrease of the intracellular free‐cholesterol pool.
In vivo homing of thymus‐enriched bone marrow cells
Authors: Klussmann Kurt G. , Haar Jack L.
Published: February 2005

A population of adult CBA/J mouse bone marrow (BM) cells enriched by in vitro migration to supernatant prepared from neonatal thymus was labeled with a DNA‐binding fluorochrome, Hoecbst dye No. 33342 (H33342). Labeled cells were injected into irradiated recipients in order to compare the in vivo localization of the migration‐enriched BM (MEBM) cells to the localization of injected nonenriched BM (NEBM) cell controls. A characteristic difference in the distribution of localized cells was observed in the spleen but not in other lymphoid organs. At 2 hr after injection the MEBM cells were located in the marginal zones surrounding the periarterial lymphoid sheaths (PALS) of the splenic white pulp. At 6 hr after injection the MEBM cells were seen distributed between marginal zones and the PALS and by 16 hr they had localized almost exclusively in the white pulp. In contrast, the NEBM cells were located in the marginal zones or red pulp for the duration of the experiment. These observations show that the MEBM cells home selectively to T‐cell areas of the spleen. Direct immunofluorescent monoclonal antibody staining of H33342‐labeled cells obtained from the recipient spleens at 16 hr demonstrated that the MEBM cells were negative for Thy‐1 antigen, indicating that acquisition of Thy‐1 was not prerequisite to the observed homing. The results are compared to known localization patterns of mature lymphocytes.
Involvement of cathepsins B and H in lysosomal degradation of horseradish peroxidase endocytosed by the proximal tubule cells of the rat kidney: I. Histochemical and immunohistochemical studies
Authors: Yokota Sadaki , Kato Keitaro
Published: February 2005

Immunohistochemical localizations of horseradish peroxidase (HRP) and cathepsins B and H in the lysosomal system of the rat kidney proximal tubule cells were investigated during the internalization and degradation of HRP by these cells. At fixed intervals after intravenous injection of HRP, the kidneys were fixed by perfusion. Five to fifteen minutes after this injection, endocytosed HRP was detected in fine granules beneath the brush border. Thirty minutes later, it accumulated into large aggregates of granules (phagosomes), where both enzymatic and antigenic activities appeared to cause HRP to be lost rapidly. After 1 hour, the aggregates of phagosomes increased in number and size but soon began to decrease gradually. In the early stage, cathepsins B and H were not detected in the apical cytoplasmic granules. However, they were present in the lysosomal compartments, together with the HRP. The large aggregates of phagosomes showed a patchy reaction, especially approximately 30 minutes after injection, whereas other medium‐sized phagosomes were stained heavily. Aggregates of phagosomes were present only in the S1 segment. These results suggest strongly that cathepsins B and H are involved in the cellular degradation of endocytosed HRP.
Development of Bone‐like substance in cartilaginous rat nasal septum under experimental conditions
Authors: Tsao S. W. , Chuah M. I.
Published: February 2005

The anterior part of the mammalian nasal septum (NS) persists throughout the life span as hyaline cartilage, in contrast to cartilage in most parts of the body, which is gradually replaced by bone during development. In this study, we have cultured differentiating rat NS under various experimental conditions in an attempt to gain some insight into the osteogenic potential, if any, of the NS and its surrounding connective tissue. Differentiating NS from E15 and E19 rat embryos were dissected and grown under the following conditions: 1) organ cultured in Waymouth's medium or modified Eagle's medium, with or without serum; 2) cultured on chick chorioallantoic membrane (CAM); 3) implanted under rat kidney capsule (KC). Bone‐like substance (BLS) never developed in organ cultures, but was observed in CAM cultures and KC implants after 7 days. The BLS was located external to the perichondrium of the NS and was stained red by the van Gieson's technique, indicating the presence of mature collagen. Further evidence of its bone‐like characteristics was demonstrated by the presence of alkaline phosphatase and type I collagen. The CAM and KC represent two experimental conditions under which progenitor cells in the nasal septum area may be induced to synthesize BLS.
Anatomical basis of a passive mechanism for ovum retention at the ampulloisthmic junction
Authors: Halbert Sheridan A. , Szal Sara E. , Broderson Stevan H.
Published: February 2005

The unexplained behavior of egg retention at the ampulloisthmic junction (AIJ) is a mechanical phenomenon; therefore the key to this process must lie in the anatomy of the oviduct. To investigate the concept that simple anatomical differences between ampulla and isthmus cause AIJ retention, we quantified, in these two regions of the rabbit oviduct, the structural characteristics of the tubal wall that show marked differences: wall thickness and luminal caliber. The oviductal wall greatly increases in thickness and decreases in luminal caliber abruptly at the transition from ampulla to isthmus. These passive mechanical factors predict a dramatically reduced distensibility of the isthmic wall compared to that of the ampulla, and these factors provide us with a simple model to account for the apparent sphincteric activity of the AIJ. Actual measurements of tubal distensibility confirmed our prediction. In addition, egg transport studies following microsurgical removal of the AIJ showed normal transport, an indication that no special structure need exist at the AIJ. We conclude that the contrasting morphology of the ampulla and isthmus may suffice to explain AIJ retention, and no special active mechanism need be postulated.
Changes in the distribution of microtubules in rat Sertoli cells during spermatogenesis
Authors: Vogl A. W.
Published: February 2005

I have studied the distribution of microtubules in rat Sertoli cells during spermatogenesis. The distribution of microtubules was determined by indirect immunofluorescence in fragments seminiferous epithelium which were mechanically dissociated from perfusion‐fixed tests. The presence of microtubules in regions indicated by immunofluorescence was confirmed with electron microscopy.

Microtubules are not evident in Sertoli cell regions surrounding early spermatogenic cells, but are abundant in cytoplasm adjacent to apical crypts containing elongate spermatids. In regions surrounding crypts, microtubules are uniformly aligned parallel to the long axis of Sertoli cells. Microtubules in these more central, or columnar, regions of the cells extend from supranuclear levels to the apex of the epithelium. In apical processes surrounding late spermatids, microtubules conform to the contours of the hook‐shaped spermatid heads. These microtubules appear continuous with those in the columnar regions of the Sertoli cells.

Changes in microtubule distribution observed in the rat are generally similar to, but less elaborate than, those reported previously in the squirrel. These changes may be characteristic of mammalian spermatogenesis in general.
Effects of starvation, feeding, and time of day on the activity of proton transport adenosine triphosphatase in the parietal cells of the mouse gastric glands
Authors: Coulton Gary R. , Firth J. Anthony
Published: February 2005

The effects of starvation, feeding, and time of day on mouse gastric glands were studied by means of an enzyme histochemical method for K+ ‐dependent p‐nitrophenyl phosphatase (K+ ‐NPPase), a partial reaction of the proton pump AT‐ Pase which drives gastric acid secretion. The stomachs of mice starced for 24 h showed very low levels of parietal cell K+ ‐NPPase histochemical reaction. However, a brief meal following such a period of starvation produced an abrupt increase in K+ ‐NPPase reaction within most of the parietal cell‐containing glands though not all parietal cells were equally susceptible to stimulation. The number of glands containing K+ ‐NPPase‐reactive cells fell slowly in the hours following a feeding stimulus. These changes were shown to be causeds by feeding rather than by general arousal and to follow the feeding cycle in and libitum fed animals. The reasons that parietal cells in the basal parts of mouse gastric glands cannot be induced to show K+ ‐NPPase reactivity by a feeding stimulus are not understood.
Specific configurations of fibronectin‐containing particles correlate with pathways taken by neural crest cells at two axial levels
Authors: Brauer Philip R. , Markwald Roger R.
Published: February 2005

Although neural crest (NC) cells can potentially enter a number of intertissue spaces, they select a particular pathway that varies depending on the axial level. In the cranial region, NC cells enter the dorsal‐lateral pathway (i.e., immediately subjacent to the ectoderm) and avoid the ventral pathway (i.e., pathway between the mesoderm and neural tube and within the mesodermal cell population), whereas in the trunk region, the majority of the NC cells enter the ventral pathway (i.e., between the somite and neural tube) and not the dorsal‐lateral pathway. Our working hypothesis is that one determining factor in directing NC cell migration is the composition and/or intermolecular associations of the extracellular matrix (ECM) in these pathways. Histochemical staining, immunostaining, and lectin‐binding studies on cryofixed and conventionally fixed tissue were conducted to initially characterize the ECM found in potential NC cell pathways prior to and during initial NC cell migration at two different axial levels. We found that, regardless of the axial level, the pathways into which NC cells eventually enter possessed a characteristic ECM arrangement. This arrangement included: (1) the presence of multicomponent, glycoprotein‐containing spherical particles (0.1–0.5 μm in diameter); and (2) a low‐sulfated ECM content. Although all particles contained fibronectin, only those in specific regions were able to bind to a monoclonal antibody directed to the cell‐binding domain of fibronectin, suggesting that the conformation of fibronectin may be important in the expression of any in situ function of the molecule.
Lumbrical muscle function as revealed by a new and physiological approach
Authors: Ranney Donald , Wells Richard
Published: February 2005

The lumbrical muscle is clearly one of several possible extensors of the interphalangeal joints. With an origin on the flexor digitorum profundus tendon it is credited with unloading the elastic tension across the interphalangeal joints and thereby facilitating their extension. Its role at the metacarpophalangeal joint is not a matter of universal aggreement. Attempts to simulate its action with weights over pulleys have not clarified this role, since true simulation would require the development of a means of applying force along the course of the lumbrical without pre‐determining which end would move. Such a system is herein described; it uses a Bowden cable, which is commonly used to activate the brakes of a bicycle. After constructing length‐tension curves of the profundus muscle in four fresh cadavers prior to the onset of rigor mortis, the interaction of realistic lumbrical loads with profundus elastic tension was studied. By contraction a lumbrical muscle adds a small but significant flexor force at the metacarpophalangeal joint, and thereby it is also capable of contributing to radial deviation and possibly rotation. As it runs from a flexor tendon to an extensor tendon and is endowed with a great many muscle spindles the lumbrical could play a part in the control of finger movement by monitoring the rate of hand closing during grasp.
Light and scanning electron microscopic observations of the canalicular system in human cellular cementum
Authors: Ismail Osama S. , Weber Dennis F.
Published: February 2005

A scanning electron microscopic cast technique was used to determine the nature of the canalicular system in human cellular cementum. Prior light microscopic observations suggested the presence of two distinct types of lacunae: bonelike and a large irregular type generally confined to the interradicular region. Only the bone‐like lacunae were visualized in the SEM cast preparations. The canalicular system associated with the bone‐like lacunae was usually continuous from the surface of the dentin to the surface of the cementum in newly‐erupted teeth. Casts having a sponge‐like configuration were observed near the cementodentinal junction in some of the specimens from the interradicular region. The presence of these casts could not be predicted from prior light microscopic observations and it was concluded that they may represent infiltration of hypomineralized matrix rather than lacunae.
Distribution of the mineralized tissues in the nasal ventral conchae (Os conchae nasalis ventralis) of pigiets after birth: Relationship with atrophic rhinitis
Authors: Trépanier Hélène , Martineau Guy‐Pierre , Martineau‐Dlzé Béatrice
Published: February 2005

Serial undecalcified cross sections were examined in order to establish the distribution of calcified cartilage, woven and lamellar bones in the nasal ventral conchase of piglets aged between birth and six weeks. The distribution of the mineralized tissues varied according to the age of the piglets and to the level of cross sections. The nasal ventral conchae were found to arise from an ossification center located at the level of the second premolar tooth. A correlation between the distribution of the different mineralized tissues of the nasal ventral conchae and the distribution of the lesions of atrophic rhinitis in the nasal ventral conchae as well as the receptivity period of piglets to the disease as observed in the literature have been discussed.
Changes in the pattern of intercellular transfer of Lucifer yellow between villus epithelial cells during postnatal development
Authors: Cheng Hazel , Bjerknes Matthew
Published: February 2005

We demonstrate the pattern of intercelluar transfer of Lucifer yellow between villus epithelial cells during postnatal development. Epithelial cells in all villi from newborn mice demonstrate high dye transfer efficiency. The efficiency of dye transfer decrease with the age of the mouse and with villus size, until in adult mice, dye transfer is observed only in what are presumably newly forming villi. We suggest that the development of an osmolality gradient in taller villi, a result of sodium pumps and a countercurrent multiplier, may be responsible for the changes in the pattern of dye transfer observed.
Clinical prosection for dental gross anatomy: A medial approach to the pterygomandibular space
Authors: Shaw Marjorie D. , Fierst Patricia
Published: February 2005

This paper describes a prosection of the pterygomandibular space from a medial perspective, as the dentist would encounter it. The prosection is performed on a bisected head, with vertebrae removed. The preparation can be used to demonstrate to the student the exact course of a needle during an inferior alveolar nerve block. The anatomical structures involved in performing the conventional, Gow‐Gates, or Akinosi injection techniques are directly compared. The impingement of a misplaced needle on neighboring structures can be demonstrated.
Morphological and biochemical changes in the adult male rat reproductive system following long‐term treatment with 1,2‐dibromo‐3‐chloropropane
Authors: Ahmad N. , Wisner J. R. , Warren D. W.
Published: February 2005

Adult Long‐Evans male rats were treated with various dosages of pure or technical grade 1,2‐dibromo‐3‐chloropropane (DBCP), epichlorohydrin (Epi), or allyl chloride (AC) for 1, 3, or 6 months on a daily basis. AC, which is the substrate for the production of DBCP, and Epi, which is a contaminant and/or metabolite of DBCP, had no effect on any of the parameters of the male reproductive system studied. The deleterious effects on male reproduction are therefore attributable specifically to DBCP. The effects of DBCP were dose and duration dependent. At the lowest dose (1 mg/kg) DBCP did not have any discernible effects on the male reproductive system. By 3 months of treatment at the intermediate dose of 5 mg/kg, the morphology of the testis ranged from normally appearing seminiferous tubules to ones which contained Sertoli cells only. At 6 months of treatment there was a reduction in the weights of the testes and sexual accessory glands. At the highest dose, the majority of the rats showed advanced testicular regression by 1 month of treatment. The most extreme testicular regression was observed in the 6‐month treatment group. Almost all of the seminiferous tubules of all of the rats were composed of Sertoli cells only. In some of the animals, a few isolated seminiferous tubules contained an occasional spermatogonium or primary spermatocyte. Some of the Leydig cells of the rats in this group showed morphological evidence of atrophy as evidenced by the clumping of chromatin and paucity of stainable cytoplasm. This was confirmed by lower levels of intratesticular testosterone, a significant reduction in the number of luteinizing hormone (LH) receptors and increased serum levels of LH and follicle‐stimulating hormone (FSH). From these results we conclude that DBCP is a specific male gonadotoxin and that the effects are not a result of contamination or metabolism. The effects appear to be a direct action at the testicular level because feedback inhibition to the pituitary gland was adversely affected.
Thy‐1 positive tingible body macrophages (TBM) in mouse lymph nodes
Authors: Smith John P. , Kosco Marie H. , Tew John G. , Szakal Andras K.
Published: February 2005

This study was prompted by the observation that cells in mouse lymph nodes (LN) with cytological characteristics of tingible body macrophages (TBM) appeared to be Thy‐1 positive. The objective of this study was to determine if these large cells were TBM and to conclusively demonstrate their reactivity for Thy‐1. The cells were studied using monoclonal antibodies (MoAb) against Thy‐1 and macrophage markers including F4/80 and Ia antigens at both light microscopic (LM) and electron microscopic (EM) levels. Immunocytochemical reactivity by TBM for Thy‐1 antigen specific MoAb was demonstrated by LM in both in situ and in vitro LN preparations. Furthermore, ultrastructural examination of these germinal center cells in situ demonstrated that the Thy‐1 reactivity visualized at the LM level was associated with ribosomes and endoplasmic reticulum as well as their plasma membrane. Similarly, these cells expressed intracytoplasmic and membrane reactivity for Ia antigens and also for the macrophage specific antigen F4/80. This indicates that the reactivity is due to active synthesis of the Thy‐1 antigen and not attributable to reactivity of any phagocytosed Thy‐1 positive cells. As defined by their germinal center location and morphological characteristics, these Thy‐1 reactive macrophages were identified as TBM. Germinal center TBM thus represent a unique, vigorously phagocytic subset of mature macrophages which express both macrophage and thymocyte markers.