bluuebunny/crossref_metadata_2025 huggingface dataset:
Aberrant differentiation of neuroepithelial cells in developing mouse brains subsequent to retinoic acid exposure in utero
Authors: Yasuda Yoshiko , Konishi Hiroyoshi , Matsuo Takuya , Kihara Takahide , Tanimura Takashi
Published: February 2005

All‐trans‐retinoic acid induced 2 types of disorganized neuroepithelium, localized and continuous, in the exencephaly of 9‐day‐old mouse embryos exposed to 60 or 40 mg/kg for 27 to 30 hr in utero. The localized effect appeared as a protuberance in the wall of the telencephalon and thick neural folds in the mesencephalon with the discontinuity of the apical terminal sheet. The continuous disorganization was seen from the olfactory placode to the myelencephalon with rosettes of cells and many dense bodies in the neuroepithelium. Ultrastructurally, cells in the localized disorganizations showed swelling of Golgi complexes, coated vesicles, and rough endoplasmic reticulum resulting in degeneration. The continuous disorganizations consisted of undifferentiated homogeneous cells in which the nuclei exhibited expansion of nucleolar granular portions and coagulated heterochromatin, and cytoplasm showed monosomal dispersion. In both types of disorganized neuroepithelium, junctional complexes were seen focally at the apical side or apical processes of the rosette, with few or no microfilament bundles. A layer of microfilaments at the base of the neuroepithelial cells in controls, just above the basal lamina, was not present in the monosome dispersed cytoplasm. In the neuroepithelium of controls, one phagosome was seen in the perinuclear region in 0.8% of the cells examined, whereas in the experimental neuroepithelium 2 or more phagosomes were seen in a cell, and phagocytosis occurred by pseudopods. These findings suggest that all‐trans‐retinoic acid induces not only cytotoxicity but also dedifferentiation in the neuroepithelial cells leading to more cell death, which activates the phagocytosis. These lesions in the neuroepithelium may be a cause of exencephaly.
Morphology of pulmonary intravascular macrophages (PIMs) in ruminants: Ultrastructural and cytochemical behavior of dense surface coat
Authors: Atwal O. S. , Minhas K. J. , Ferenczy B. G. , Jassal D. S. , Milton D. , Mahadevappa V. G.
Published: February 2005

Recent studies have indicated that pulmonary intravascular macrophages (PIMs) are a resident cell population which in structure and function resemble mature macrophages of the mononuclear phagocyte system (MPS) in various domestic species, particularly the ruminants. The ultrastructural features of PIMs of the goat and calf lungs were studied by using vascular perfusion and direct airway instillation of fixatives. Staining with tannic acid as a component of paraformaldehyde‐glutaraldehyde‐based fixative revealed the presence of an electron‐dense coat on the surface of the cell membrane of the PIMs. The surface coat disappeared after heparin infusion and after enzymatic digestion with lipolytic lipase, suggesting that the surface coat was predominantly lipoprotein in nature. The lipoprotein coat was organized in the form of a linear chain of spherical globules with a consistent periodicity created by the intervening translucent space between individual globules. The surface coat was separated from the outer‐leaflet of the cell membrane by an empty space measuring 35–39 nm in width. PIMs possessed a significant number of coated pits and coated vesicles, the cell organelles of receptor‐mediated endocytosis of lipoproteins. In concurrence with the coated pits and vesicles, microtubules, multivesicular bodies, and lipoprotein‐positive vesicles were also observed. It is conceivable that PIMs are involved in lipid metabolism and are the major source of vasoactive substances, which significantly influence both the dynamics of pulmonary circulation and the surfactant turnover of the ruminant lung.
Ultrastructural morphometric analysis of cultured neonatal and adult rat ventricular cardiac muscle cells
Authors: Delcarpio Joseph B. , Claycomb William C. , Moses R. L.
Published: February 2005

Neonatal and adult rat ventricular cardiac muscle cells cultured on laininin differed from similar myocytes grown on plastic in the amount and distribution of their mitochondria and transverse tubules. Point‐count morphometry was used at the electron microscopic level to quantify these differences. Adult myocytes grown on laminin contained more mitochondria per unit volume than adult myocytes grown on plastic. No significant differences were observed in the volume percent of myofibrils in either adult or neonatal ventricular myocytes when grown on laminin and compared to those grown on plastic. The transverse tubule system in neonatal and adult myocytes was reduced significantly when both groups were cultured on laminin. Furthermore, neonatal and adult myocytes cultured on laminin were flatter than those cultured on plastic. This may indicate a relationship between the surface/volume ratio and transverse tubule development in cultured myocytes. These studies establish that point‐count morphometry can be used to quantify changes in the organelle volume densities of cultured cardiac muscle cells.
Condensation of hypertrophic chondrocytes at the chondro‐osseous junction of growth plate cartilage in Yucatan swine: Relationship to long bone growth
Authors: Farnum Cornelia E. , Wilsman Norman J.
Published: February 2005

Chondrocytes of the cartilaginous growth plate are found in a spatial gradient of cellular differentiation beginning with cellular proliferation and ending with cellular hypertrophy. Although it is recognized that both proliferation and hypertrophy contribute significantly to overall bone growth, mechanisms acting on the chondrocyte to control the timing, the rate, and the extent of hypertrophy are poorly understood. Similarly, mechanisms acting on the terminal chondrocyte to cause its death at the chondro‐osseous junction have not been investigated. In this study we examine the condensation of terminal hypertrophic chondrocytes in proximal and distal radial growth plates of Yucatan swine at 4 weeks of age. The animals were raised in a controlled environment where activity and feeding patterns were synchronized to a given time in the light/dark cycle. We analyzed cellular condensation both as a function of circadian rhythms in a 24‐hr time period, and as a function of overall rate of growth. The data suggest that the magnitude of circadian influences on long bone growth is significantly damped at the level of the hypertrophic chondrocyte compared to that seen by previous investigators studying circadian influences on chondrocytic proliferation. Secondly, the condensation of hypertrophic chondrocytes at the chodro‐osseous junction varies inversely with rate of growth in length of the bone. At any time period, a higher percentage of terminal chondrocytes in the condensed form was found in the slower‐growing of the two growth plates. We relate these findings to current hypotheses concerning controls of chondrocytic hypertrophy and possible controls over the timing of hypertrophic cell death.
Covalent affinity labeling, radioautography, and immunocytochemistry localize the glucocorticoid receptor in rat testicular leydig cells
Authors: Stalker Alison , Hermo Louis , Antakly Tony
Published: February 2005

The presence and distribution of glucocorticoid receptors in the rat testis were examined by using 2 approaches: in vivo quantitative radioautography and immunocytochemistry. Radioautographic localization was made possible through the availability of a glucocorticoid receptor affinity label, dexamethasone 21‐mesylate, which binds covalently to the glucocorticoid receptor, thereby preventing dissociation of the steroid‐receptor complex. Adrenalectomized adult rats were injected with a tritiated (3H) form of this steroid into the testis and the tissue was processed for light‐microscope radioautography. Silver grains were observed primarily over the Leydig cells of the interstitial space and to a lesser extent, over the cellular layers which make up the seminiferous epithelium, with no one cell type showing preferential labeling. To determine the specificity of the labeling, a 25‐ or 50‐fold excess of unlabeled dexamethasone was injected simultaneously with the same dose of (3H)‐dexamethasone 21‐mesylate. In these control experiments, a marked reduction in label intensity was noted over the Leydig as well as tubular cells. Endocytic macrophages of the interstitium were non‐specifically labeled, indicating uptake of the ligand possibly by fluid‐phase endocytosis. A quantitative analysis of the label confirmed the presence of statistically significant numbers of specific binding sites for glucocorticoids in both Leydig cells and the cellular layers of the seminiferous epithelium; 86% of the label was found over Leydig cells, and only 14% over the cells of the seminiferous epithelium. These binding data were confirmed by light‐microscope immunocytochemistry using a monoclonal antibody to the glucocorticoid receptor. Intense immunocytochemical staining was seen predominantly in the cytoplasm of the Leydig cells, whereas the cells of the seminiferous epithelium were weakly stained. Thus, the present data reveal a high glucocorticoid receptor content within Leydig cells and a lower level within cells of the seminiferous epithelium. Furthermore, the present experiments demonstrate for the first time the usefulness of dexamethasone 21‐mesylate as an affinity label for the morphological localization of the glucocorticoid receptor. The localization of glucocorticoid receptors in Leydig cells suggest a role for this steroid in regulating the function of these cells.
Innervation of the renal proximal convoluted tubule of the rat
Authors: Barajas Luciano , Powers Kenneth
Published: February 2005

Experimental data suggest the proximal tubule as a major site of neurogenic influence on tubular function. The functional and anatomical axial heterogeneity of the proximal tubule prompted this study of the distribution of innervation sites along the early, mid, and late proximal convoluted tubule (PCT) of the rat. Serial section autoradiograms, with tritiated norepinephrine serving as a marker for monoaminergic nerves, were used in this study. Freehand clay models and graphic reconstructions of proximal tubules permitted a rough estimation of the location of the innervation sites along the PCT. In the subcapsular nephrons, the early PCT (first third) was devoid of innervation sites with most of the innervation occurring in the mid (middle third) and in the late (last third) PCT. Innervation sites were found in the early PCT in nephrons located deeper in the cortex. In juxtamedullary nephrons, innervation sites could be observed on the PCT as it left the glomerulus. This gradient of PCT innervation can be explained by the different tubulovascular relationships of nephrons at different levels of the cortex. The absence of innervation sites in the early PCT of subcapsular nephrons suggests that any influence of the renal nerves on the early PCT might be due to an effect of neurotransmitter released from renal nerves reaching the early PCT via the interstitium and/or capillaries.
Crypt base columnar cells in ileum of BDF1 Male Mice—their numbers and some features of their proliferation
Authors: Chwalinski S. , Potten C. S.
Published: February 2005

Some features of the proliferative cells at the bottom of the ileal crypts in BDF1 mice have been studied in relation to the distribution of Paneth cells (PC) in an attempt to clarify the nature and function of these crypt base columnar cells (BCC) and to elucidate some aspects of the role of the microenvironment created by the PC.

Longitudinal sections of crypts have shown that the ratio of PC to the BCC, which are scattered amongst the PC, is 2.7:1 in sections or approximately 29 PC and 9 BCC per whole crypt, i.e., a ratio of 3.2:1. The labelling index of BCC is about 35%, which is comparable to that of mid‐crypt columnar cells. Although the BCC do become labeled, it is concluded that they cannot create vertical pairs or runs of several adjacent BCC since this would seriously disturb the distribution of Paneth cells. Only in dividing crypts are such runs (consisting of 3 to 5 cells) observed. The ability of BCC to synthesize DNA is not dependent on their position in the Paneth cell zone. In 95% of the crypts, the highest Paneth cell is below the 7th cell position from the bottom of the crypt, and the positions of the highest PC on either side of a given crypt are similar. The secreted granules or the cytoplasm of PC specifically bind pokeweed lectin, and this can be used for identification.

Tracer doses of 3HTdR (37 kBq/gm body weight) result in the histological death of some BCC, and these damaged cells are evenly distributed throughout the Paneth cell zone. These tracer doses are somewhat selectively incorporated into BCC, i.e., the BCC have a higher grain count in autoradiographs, probably because they possess more thymidine kinase enzyme activity. This ability is very sensitive to the withdrawal of food, because 24 hr of fasting abolished the observed gradient in the intensity of labelling, which is very well correlated with the distribution of BCC.

Regeneration of the crypts following cytotoxic exposure to Ara‐C is initiated at the base of the crypt and hence may involve the BCC with possible help from the Paneth cells. The latter are insensitive to cytotoxic (S phase specific) agents and may help in the regeneration by preserving the architecture of the base of the crypt.
Fine structure of the dorsal lingual epithelium of the lizard, Gekko japonicus (Lacertilia, Gekkonidae)
Authors: Iwasaki S.
Published: February 2005

Three different types of lingual papilla were observed by scanning electron microscopy on the dorsal lingual epithelium of the lizard Gekko japonicus. Dome‐shaped lingual papillae were located at the apex. Flat, fan‐shaped lingual papillae were seen in the widest area of the lingual body. Long, scale‐like lingual papillae were arranged on the latero‐posterior dorsal surface. At higher magnification, microvilli and microridges were seen to be widely distributed over the surface of the papillae. By light microscopy, the epithelium of the dome‐shaped papillae was composed of single, columnar epithelial cells filled with secretory granules. The tip of the epithelium of the fan‐shaped and scale‐like papillae was composed of stratified squamous epithelial cells without granules. The major part of the epithelium of these two types of papilla, except the tip area, was also composed of single, columnar epithelial cells with secretory granules. By transmission electron microscopy, a nucleus without a defined shape was seen to be located in the basal part of each of the single, columnar epithelial cells. Rough‐surfaced endoplasmic reticulum and Golgi apparatus were well developed around the nucleus. The other, major part of the cytoplasm was filled with the spherical secretory granules, a large number of which had very electron‐dense cores and moderately electron‐dense peripheral regions. In the stratified squamous epithelium, a nucleus, which tended to be condensed on the free‐surface side, was located in the center of each cell. Mitochondria, endoplasmic reticulum, and vesicles were observed in the cytoplasm.
Ultrastructural features of mitochondria‐rich cells in stenohaline freshwater and seawater fishes
Authors: Pisam M. , Boeuf G. , Prunet P. , Rambourg A.
Published: February 2005

In order to elucidate the functional significance of accessory cells in freshwater fishes, such as the rainbow trout, which displays a poor adaptability to seawater life, a search for such cells was performed in two stenohaline freshwater fishes: the loach and the gudgeon. Accessory cells were never encountered in these species; but, in contrast, two types of chloride cells were observed consistently that strikingly resembled the α‐ and β‐cells previously described in the guppy, a freshwater‐adapted euryhaline fish. The α‐cell, a pale and elongated chloride cell, was located at the base of the secondary lamellae in close contact with the arterioarterial pillar capillary. Darker, ovoid chloride cells resembling the β‐cell were found exclusively in the interlamellar region of the primary epithelium facing the central venous sinous. The latter cells frequently formed multicellular complexes linked together by deep, narrow, apical junctions.

In another experiment, a stenohaline seawater fish, the turbot, was adapted to diluted 5% saltwater and to fresh water. In seawater, the gill epithelium contained only one type of chloride cell, always associated with accessory cells. Due to numerous cytoplasmic interdigitations between the accessory cells and the apical portion of the chloride cell, there was a noticeable increase in the length of the shallow apical junction, sealing off the intercellular space between the two cell types. In 5% saltwater, there was a decrease in the number of these interdigitations and a concomitant decrease in the length of the shallow apical junction. In fresh water, chloride cells were partially or completely separated from the outside medium by modified accessory cells.

It is thus concluded that accessory cells are found exclusively in fish living in seawater or preadapted to seawater and that they probably are involved in the formation and modulation of paracellular pathways for ionic excretion. In contrast, the respective roles of the two types of chloride cells observed in freshwater fishes are still to be determined.
Effect of photoperiod on pineal gland volume and pinealocyte size in the chinese hamster, Cricetulus griseus
Authors: Matsushima Shoji , Sakai Yuko , Hira Yoshiki
Published: February 2005

Male adult (200‐day‐old) Chinese hamsters (Cricetulus griseus) raised from weaning under either LD 16:8 or LD 8:16 were used. The pineal gland of the Chinese hamster consists of superficial (major) and deep (minor) components and a continuous, or interrupted, narrow parenchymal stalk interposed between them. The volume of the superficial pineal including the parenchymal stalk is greater under LD 16:8 than under LD 8:16. Under both photoperiods, pinealocytes in the superficial pineal have larger nuclei and more abundant cytoplasm than those in the deep pineal. Nuclei in the superficial pineal appear pale and usually have irregular profiles, whereas those in the deep pineal appear dark and have round profiles. In the superficial pineal, pinealocyte nuclei are larger, paler, and more irregular; and, in addition, nuclear density is lower under LD 16:8 than under LD 8:16. Similar, but less prominent, photoperiod‐induced changes occur in the volume of the deep pineal, the size of pinealocytes, and pinealocyte nuclear morphology in the deep pineal. The results indicate that the development and differentiation of pinealocytes in both pineal portions may be advanced under long photoperiods and delayed under short photoperiods, although pinealocytes in the deep pineal may remain not fully differentiated even in adults. Since testicular weights and body weights are similar under both photoperiods, the photoperiod may exert marked influences on the development of the pineal gland without affecting reproductive activity and growth rates of animals.
Comparative distribution of carbonic anhydrase isozymes III and II in rodent tissues
Authors: Spicer Samuel S. , Ge Zhen‐Hau , Tashian Richard E. , Hazen‐Martin Debra J. , Schulte Bradley A.
Published: February 2005

Carbonic anhydrase (CA) III was demonstrated immunocytochemically in epithelium in some regions of salivary gland ducts, colon, bronchi, and male genital tract and in adipocytes, in addition to skeletal muscle and liver where the isozyme was previously localized. Basal cells beneath the submandibular gland's excretory ducts in guinea pig stained for CA III. Carbonic anhydrase III occurred alone in some and with CA II in other sites but was often absent from CA‐II‐containing types of cells. This was exemplified by CA III's abundance in CA‐II‐positive proximal colon and its sparsity in the CA‐II‐rich distal colon of the mouse. Striated ducts in guinea pig, but not mouse salivary glands, stained darker for CA and appeared accordingly to function more actively in ion transport compared with excretory ducts. Carbonic anhydrase content varied among genera in liver and pancreas and between mouse species and strains in salivary glands and kidney. Newly observed murine sites of CA II activity included Auerbach's plexus and a population of leukocytes infiltrating the lamina propria in small intestine, and several types of cells in the male genital tract. In immunoblot tests, antisera to CA III showed no cross reactivity with antisera to CA II, but those to CA II disclosed weak cross reactivity with CA III.
Oviductal epithelium of the baboon: Hormonal control and the immuno‐gold localization of oviduct‐specific glycoproteins
Authors: Verhage Harold G. , Mavrogianis Patricia A. , Boice Melinda L. , Li Weiguo , Fazleabas Asgerally T.
Published: February 2005

Oviducts were obtained from a series of cycling and ovariectomized steroidtreated baboons. The lining epithelium of the ampulla and isthmus was analyzed by light and electron microscopy. Both morphological and cytomorphometric analyses revealed that the morphological and functional state of the oviductal epithelium in the baboon is controlled by the ovarian steroids. Additionally, a clear cephalocaudal steroid‐responsive gradient was observed when the data from the ampulla and isthmus of the same animal were compared. Within the ampulla, estradiol induced hypertrophy, hyperplasia, ciliogenesis, and secretory activity, whereas adding progesterone to the treatment regimen (± estradiol) resulted in atrophy, deciliation, apoptosis, and loss of the secretory activity. These cyclic processes were less evident in the isthmus. We also used an indirect electron microscopic immunogold technique and a previously characterized polyclonal antibody to determine the localization of oviduct‐specific glycoproteins. These glycoproteins were present in every secretory granule observed, regardless of oviduct region, electron density, or size of the secretory granule. In summary, our data show that (1) estradiol induces and maintains the mature epithelium of the baboon oviduct, (2) steroid withdrawal or the administration of progesterone causes regression of the epithelium, and (3) the previously identified estradiol‐dependent oviduct‐specific glycoproteins are synthesized within and released from the secretory epithelial cells.
Effect of altered occlusal function on transseptal ligament and new bone thicknesses in the periodontium of the rat
Authors: Johnson Roger B.
Published: February 2005

Alteration of tooth function is assumed to change stress/strain on the adjacent alveolar bone and its mucoperiosteum, producing changes in morphology similar to those described for other load‐bearing bones. The present study suggested that crestal alveolar bone and its mucoperiosteum respond differently to stress/strain than load‐bearing bones in other locations, possibly due to differences in the mechanism of bone loading by muscles and teeth. Occlusal hypofunction was initiated by extraction of agonist teeth; the contralateral teeth were placed in hyperfunction by the surgery. Untreated animals were also studied. 3H‐proline was injected, animals were killed 1–5 weeks later, and the thicknesses of new bone and transseptal ligament were measured. After 5 weeks of altered function, total thickness (new bone + transseptal ligament) was similar in untreated and in hypofunctional and hyperfunctional situations; however, a new ratio between transseptal ligament and new bone thicknesses was established. Occlusal force was negatively correlated with new bone and positively correlated with transseptal ligament thickness; both thicknesses were statistically correlated in each functional situation (P<0.001). Hyperfunction resulted in increased transseptal ligament thickness, but decreased new bone thickness as compared to untreated controls (P<0.001). In contrast, hypofunction resulted in an increased new bone thickness, but a decreased transseptal ligament thickness (P<0.001). Tissue responses assure appropriate support for the teeth in each functional situation.
“Intermediate zone” of mammalian spleens: Light and electron microscopic study of three primitive mammalian species (platypus, shrew, and mole) with special reference to intrasplenic arteriovenous communication
Authors: Tanaka Yasukazu
Published: February 2005

The intermediate zone (IZ) of nonperfused and perfused spleens in three species of primitive mammals (shrew, mole, platypus) was studied morphologically. The IZ is a tissue zone consisting of plexiform vessels, probably venous capillaries, and is located transitionally between the white and red pulp. The IZ is separated from the white pulp by the arterial net (AN), in which the white pulp arteries terminate. Development of the IZ differs between the three species examined being distinctive in the platypus and shrew. The IZ is thin in the mole spleen. A closed type of arteriovenous (A‐V) anastomosis was demonstrated in or around the IZ in the two Insectivora species examined. In the shrew spleen, peripheral arterial branches running within the IZ anastomose with the AN around the follicle. The AN anastomoses eventually with venous plexi‐form vessels of the IZ around the nonfollicular area of the white pulp to form a closed system. In the mole spleen, A‐V anastomoses were noted between white pulp arteries (follicular and AN) and veins of the red pulp, either by direct communication or through fenestrated IZ vessels compatible with the plexiform vessels of the shrew spleen. A‐V anastomosis in the IZ is probable, but not confirmed, in the platypus spleen, as analysis was limited to a nonperfused specimen. Well‐developed ellipsoids were noted around arterial terminals of the IZ in the shrew spleen. Ellipsoids were also noted around all arterial terminals of the mole spleen directed to the red pulp. Most ellipsoids of the mole spleen appeared located within the IZ. No ellipsoids were present around arterial terminals of the IZ in the platypus spleen.

Closed circulation was noted in terminals of the pulp artery in spleens of all three species. All pulp arteries of the mole spleen are postellipsoid segments of white pulp (AN and follicle) arteries. No ellipsoids were found around terminals of the pulp artery (penicillar artery) in shrew and platypus spleens.

The IZ is probably homologous to the perilymphatic sinusoid (vein) of the lungfish spleen and may be regarded as part of the red pulp. The IZ may be representative of primitive mammalian spleens that have closed circulation. The marginal zone (MZ) of common mammalian spllens is probably a modified IZ by differentiation (remodelling) of the intrasplenic vein. In this process, with drawal of venous vessels from the IZ occurrred, leaving a lymphoreticular zone with open circulation (MZ). The marginal sinus reported in some mammalian spleens is probably a modified AN formed durig this process. Possible morphological alterations of the spleen in vertebrate phylogeny are discussed.
Presence in chicken tibialis anterior and extensor digitorum longus muscle spindles of reactive and unreactive intrafusal fibers after incubation with monoclonal antibodies against myosin heavy chains
Authors: Maier Alfred , Zak Radovan
Published: February 2005

Cross and longitudinal sections from the encapsulated portions of chicken tibialis anterior and extensor digitorum longus muscle spindles were examined to determine whether their intrafusal fibers were a structurally homogeneous or heterogeneous population. The techniques used were the histochemical actomyosin (mATPase) reaction, and fluorescence immunohistochemistry employing two monoclonal antibodies, CA‐83 and CCM‐52, that are specific for myosin heavy chains. After incubation with antibody CCM‐52, intrafusal fibers fluoresced either strongly or weakly to moderately. Antibody CA‐83 was even more selective. In addition to identifying the strongly reactive category, it clearly separated the remaining fibers into unreactive and moderately reactive groups. As a whole, after incubation for mATPase, pH 9.6 preincubation, unreactive fibers stained darker than strongly reactive fibers. Moreover, the cross‐sectional area of the unreactive fibers was significantly larger than that of the strongly reactive fibers. In the average‐size muscle spindle with six intrafusal fibers, there were four unreactive fibers and two strongly reactive fibers. In about one‐third of the receptors examined, one moderately reactive fiber was present. Taken together, the data indicate that intrafusal fibers of chicken tibialis anterior and extensor digitorum longus muscles are not structurally homogeneous. The oberserved variations can be better explained in terms of different fiber types than of continuous gradients within one type of fiber.
Migration pathways of recirculating murine B cells and CD4+ and CD8+ T lymphocytes
Authors: Pellas Theodore C. , Weiss Leon
Published: February 2005

Migration pathways of B cell and CD4+ and CD8+ T cell subsets of murine thoracic duct lymphocytes (TDL) were mapped. Per weight, the spleen accumulated more TDL than any other organ, regardless of lymphocyte subset. Spleen autoradiographs showed early accumulations of TDL in marginal zone and red pulp. Many TDL exited the red pulp within 1 hr via splenic veins. The remaining TDL entered the white pulp, not directly from the adjacent marginal zone but via distal periarterial lymphatic sheaths (dPALS). From dPALS, T cells migrated proximally along the central artery into proximal sheaths (pPALS) and exited the white pulp via deep lymphatic vessels. B cells left dPALS to enter lymphatic nodules (NOD), then also exited via deep lymphatics.

T cells homed to lymph nodes more efficiently than B cells. Lymphocytes entered nodes via high‐endothelial venules (HEV). CD4+ TDL reached higher absolute concentrations in diffuse cortex than did CD8+ T cells. However, CD8+ TDL moved more quickly through diffuse cortex than did CD4+ TDL. B cells migrated from HEV into NOD. Both T and B TDL exited via cortical and medullary sinuses and efferent lymphatics. A migration pathway across medullary cords is described.

All TDL subsets homed equally well to Peyer's patches. T TDL migrated from HEV into paranodular zones while B cells moved from HEV into NOD. All TDL exited via lymphatics. Few TDL entered zones beneath dome epithelium. All subsets were observed within indentations in presumptive M cells of the dome epithelium.
Role of spermatogonia in the stage‐synchronization of the seminiferous epithelium in vitamin‐A‐deficient rats
Authors: Ismail N. , Morales C. , Clermont Y.
Published: February 2005

After 20‐day‐old rats are placed on a vitamin‐A‐deficient diet (VAD) for a period of 10 weeks, the seminiferous tubules are found to contain only Sertoli cells and a small number of spermatogonia and spermatocytes. Retinol administration of VAD rats reinitiates spermatogenesis, but a stage‐synchronization of the seminiferous epithelium throughout the testis of these rats is observed. In order to determine which cell type is responsible for this synchronization, the germ cell population has been analyzed in whole mounts of seminiferous tubules dissected from the testes of rats submitted to the following treatments. Twenty‐day‐old rats received a VAD diet for 10 weeks and then were divided into three groups of six rats. In group 1, all animals were sacrificed immediately; in group 2, the rats were injected once with retinol and sacrificed 3 hr later; in group 3, the rats were injected once with retinol, placed on a retinol‐containing diet for 7 days and 3 hr, and then sacrificed. Three rats from each group had one testis injected with 3H‐thymidine 3 hr (groups 1 and 2) or 7 days and 3 hr (group 3) before sacrifice. Three normal adult rats (approximately 100 days old) served as controls. Labeled and unlabeled germinal cells were mapped and scored in isolated seminiferous tubules. In group 1, type A1 and type A0 spermatogonia as well as some preleptotene spermatocytes were present; type A2 A3 A4 In, and B spermatogonia were completely eliminated from the testis. Neither type A1 mitotic figures nor 3H‐thymidine‐labeled‐type A1 nuclei were seen. Three hr after retinol injection (group 2), type A1 mitoses, but no labeled type A1 nuclei were observed. At 7 days and 3 hr after retinol administration (group 3), type A4 and In Spermatogonia as well as type A1 spermatogonia were present. A few residual pachytene spermatocytes were found, and some type A0 cells were labeled. These results indicate that VAD caused, in addition to an impairment of spermatogenesis at the preleptotene spermatocyte step, a selective momentary arrest of surviving type A1 spermatogonia at the G2 phase of their cell cycle. Following administration of vitamin A to VAD rats, these type A1 cells reinitiated spermatogenesis synchronously and, after several cycless of proliferation and renewai, reconstituted the seminiferous epithelium in a stage‐synchronized manner.
Regional differences in composition of the perforatorium and outer periacrosomal layer of the rat spermatozoon as revealed by immunocytochemistry
Authors: Oko R. , Moussakova L. , Clermont Y.
Published: February 2005

The rat perforatorium is the part of the perinuclear theca that underlies the acrosomic system. It appears to be composed of several polypeptides. The main objective of this study was to determine the distribution of seven of these perforatorial polypeptides in the head of the rat spermatozoon. For this purpose, polyclonal antibodies were affinity purified from these polypeptides and tested (1) for their distribution on electron‐microscope sections of late spermatids and spermatozoa by immunogold labeling and (2) for their specificity on Western blots of denatured perforatorial polypeptides by immunoblotting. Imunoblotting showed that all seven of the prominent perforatorial polypeptides had epitopes in common. Immunogold labeling of spermatozoa showed that antibodies against the 13, 13.4, and 16 kDa polypeptides were restricted in their localization to the thicker apical portion of the perforatorium and to the inner zone of the ventral spur. However, antibodies against the 34, 43, 57, and 63 kDa polypeptides reacted with the entire perforatorium but, in addition, reacted with the inner part of the ventral spur and with a portion of the “outer periacrosomal layer” lying between the plasma membrane and the outer acrosomal membrane. These results suggest (1) that there are regional differences in protein composition of the perforatorium, of the outer periacrosomal layer, and of the postacrosomal dense lamina; and (2) that perforatorial polypeptides may not necessarily be restricted to the subacrosomal region, but may also compose portions of the outer periacrosomal layer and postacrosomal dense lamina. Based on both immunoblotting and immunocytochemical results, using an antiactin monoclonal antibody that recognizes all known isoforms of actin, actin was not detected in the perforatorium of step 19 spermatids or spermatozoa. Actin, however, together with the seven perforatorial polypeptides tested, was present in the subacrosomal space of elongating spermatids before the process of condensation of the perforatorium takes place.
Abnormal manchette development in spermatids of azh/azh mutant mice
Authors: Meistrich M. L. , Trostle‐Weige P. K. , Russell L. D.
Published: February 2005

A study of manchette development during spermiogenesis in azh/azh mutant mice was carried out by thin‐section transmission electron microscopy with the goal of determining which of the initial steps in spermatid development are aberrant. In the homozygous mutant, spermatogensis was quantitatively normal; but 100% of the sperm nuclei produced had abnormal shapes. The first defect, observed in steps 8–9, was the abnormal positionning of many manchette microtubules. These microtubules were directed to wards regions of the plasma membrane not normally associated with manchette formation, in addition to being located at the caudal rim of the acrosome in the normal region of manchette formation. At steps 10–12, sheets of machette microtubules were often in ectopic positions along the plasma membrane, rather than in association with the nuclear membrane as well. The fine structural appearance of the manchette was generally normal; the defect appeared to be in its positioning within the cell. In many step 8–10 spermatids nuclear invaginations and evaginations were observed, always associated with irregularities in the position of some of the manchette microtubules; these illustrate the capacity of manchette microtubules to deform nuclear shape. The nuclear irregularities remained throughout spermiogenesis. These observations are consistent with the hypothesis that the manchette is involved in at least some aspects of sperm nuclear shaping and that the improper positioning of manchette formation is a likely candidate for the primary abnormality resulting from a defective allele at the azh locus.
Microscopic examination of porcine conceptus‐maternal interface between days 10 and 19 of pregnancy
Authors: Keys J. L. , King G. J.
Published: February 2005

Conceptus‐maternal interactions in the pig were examined at days 10, 13, 16, and 19 of pregnancy. Contact between the chorion and uterine epthelium was not preserved on day 10, but extensive contact occurred in 3 to 5 pregnant gilts on day 13 and was related to localized differentiation of the uterine epithelium. Attachment events occurred earlier and more rapidly than previously reported, commencing in the region of the embryonic disc and progressing toward the extremities of the chorionic vesicle, with stages from apposition through attachment occuring simultaneously along a conceptus at day 13 and thereafter. Apical protuberances on maternal epithelial cells and interposing blunt chorionic processes were evident at sites of early maternal conceptus interaction, but were reduced at regions exhibiting microvillous interdigitation. Placentation in the pig represents a developmental process consisting of a continuum of sequential events which occur over a broad time frame rather than at specific discrete times.
Ultrastructural study of the cellular types in the pineal organ of gambusia affinis (teleost)
Authors: Gonzalez Rosa M. , Tolivia Delio , Rodriguez‐Colunga Maria J. , Menendez‐Pelaez Armando
Published: February 2005

The pineal organ of Gambusia affinis was studied via light and electron microscopy. The cell types studied included photoreceptor cells, supporting cells, and a third cell type. The photoreceptor cells, which appear to form clusters, are divided into four regions: outer segment, inner segment, cell soma, and synaptic pedicle. Synaptic ribbons are commonly observed in the synaptic pedicle. The supporting cells separate the photoreceptor cells from the thick basal lamina that surrounds the entire pineal organ. The supporting cells show highly organized membrane formations, some lipid‐like inclusions, and a diplosome. One of the centrioles gives rise to an invaginated cilium. The third cell type is observed infrequently and appears to be located mainly in the vicinity of the outer segments. The morphological characteristics of this cell type are similar to those of phagocytic cells. The ultrastructural features of the pineal organ of G. affinis are compared with those of other teleosts.
Nerves and nerve plexuses of the human vertebral column
Authors: Groen Gerbrand J. , Baljet Bob , Drukker Jan
Published: February 2005

The origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole‐mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu‐vertebral nerves. The sinu‐vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu‐vertebral nerves are found. Most frequently three types of thick sinu‐vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu‐vertebral nerves is described.
Development of the embryonic chick wing bud from stage 24 to stage 32
Authors: Searls Robert L.
Published: February 2005

If a graft is placed in an early chick wing bud, the location of the graft after several days of further development cannot be predicted solely from the rate of proximal‐distal outgrowth. The movement of the graft depends on the rate of outgrowth of the wing but also on morphogenetic tissue movements intrinsic to the wing and on accommodation to the growth and morphogenetic movements of the body of the embryo. Numerous experiments have been reported in which tissue grafted into ectopic sites in the wing causes abnormal wing development. These experiments have been discussed in terms of pattern formation of positional information. However, until the movement of wing tissue during normal development is understood, it cannot be known in what way the development of grafts placed in ectopic sites is abnormal. Previous experiments have demonstrated that carbon particles placed in the wing move in the same manner as grafts of wing mesenchyme, but the carbon particles do not affect normal wing development. Carbon particles were placed in the wing, dorsal to the base of the wing, and cranial and caudal to the wing, to plot the expected movement of a graft and to discover how this movement can be predicted from the tissue movements at the base of the wing. It is concluded that three tissue movements are responsible for the movement of a graft. These are outgrowth at a rate determined by the rate of cell division, formation of the shoulder through caudal movement of the tissues cranial to the wing, and ventral movement of prospective flank ventral to somite 19. These three tissue movements and their influence on normal wing development are discussed.
Golden hamster myoid cells during active and inactive states of spermatogenesis: Correlation of testosterone levels with structure
Authors: Kurohmaru Masamichi , Hikim Amiya P. Sinha , Mayerhofer Artur , Bartke Andrzej , Russell Lonnie D.
Published: February 2005

Myoid cells were examined quantitatively in adult golden hamsters with active spermatogenesis and compared with hamsters in which the testes were regressed due to a modification in the light‐dark cycle. A detailed morphometric study was undertaken utilizing animals previously examined. The cell‐surface area and volumes of most organelles were not significantly different in animals which were gonadally active as compared with regressed animals. A slight, but significant, increase in nuclear volume (31%) and a slight, but significant, decrease (28%) in cell volume were recorded for regressed animals. The total volume of pinocytotic vesicles was increased dramatically (approximately threefold) in active animals in comparison with inactive animals (P<0.01), indicating that an increase in non‐specific transport across the myoid cell is associated with spermatogenic activity. Intravascularly injected horseradish peroxidase was capable of entering pinocytotic vesicles in both active and inactive animals. Plasma luteinizing hormone (LH) as well as plasma and testicular testosterone levels were weakly (r=0.64, 0.68, and 0.65, respectively), but significantly (P<0.05), correlated with cell size. Plasma and testicular testosterone were correlated with the total volume of pinocytotic vesicles (r=0.74 and 0.68, respectively). The data indicate that although the rat myoid cell possesses receptors for testosterone, there are few structural manifestations of the hamster myoid cell that correlate well with testosterone levels. Thus, the hamster myoid cell differs from two other hormone‐responsive somatic cells in the testis, the Sertoli cell and the Leydig cell, that show dramatic structural alterations with changes in gonadal activity and striking correlations of structural features with functional measures. These findings were unexpected in view of the in vitro findings that point to a major role for the myoid cell in controlling seminiferous tubule function.
Macrophage invasion and phagocytic activity during lens regeneration from the iris epithelium in newts
Authors: Reyer Randall W.
Published: February 2005

Following removal of the lens through the cornea, early stages of lens regeneration from the dorsal riris of the adult newt, Notophthalmus viridescens, were studied using light and electron microscopic observations on sectioned, plastic‐embedded irises. Specimens were fixed in Karnovsky's fixative every 2 days from 0 to 12 and 15 days after lentectomy. Infiltration of the iris epithelium by macrophages and their phagocytosis of melanosomes and small fragments of iris epithelial cells were observed. These macrophages were characterized by coarse nuclear chromatin, numerous mitochondria, free ribosomes, granular endoplasmic reticulum, Golgi complexes, vesicles, lysosomes, and phagosomes containing ingested melanosomes. Lamellipodia of varying length projected from their surface. Most of the cells lying on or close to the posterior surface of the iris could be identified as macrophages by these criteria. During this period, there was enlargement of the intercellular spaces within the iris epithelium. The iris epithelial cells near the margin of the pupil elongated, lost their melanin pgigment and some associated cytoplasm, and acquired abundant free polyribosomes to form a lens vesicle of depigmented cells.
In vivo differentiation of brown adipocytes in adult mice: An electron microscopic study
Authors: Géloën A. , Collet A. J. , Guay G. , Bukowiecki L. J.
Published: February 2005

The differentiation of brown adipocyte precursor cells was studied in interscapular brown adipose tissue of adult mice by electron microscopy. Different stages of cell differentiation were characterized in situ. Previous autoradiographic studies suggested that interstitial cells represent the precursor cells of fully differentiated brown adipocytes. The present observations provide morphological evidence for a progressive differentiation of interstitial stem cells into mature brown adipocytes. Four typical stages of development were identified: (1) interstitial cells, (2) protoadipocytes, (3) preadipocytes, and (4) mature brown adipocytes. Interstitial stem cells were small spindle shaped cells, situated between brown adipocytes and characterized by a high nuclear‐cytoplasmic ratio, the scarcity of organelles, and the absence of lipid inclusions. Protoadipocytes resembled interstitial cells except that they contained a few tiny lipid droplets in their cytoplasm. Preadipocytes had a larger cytoplasm enclosing many mitochondria and lipid droplets; the smooth endoplasmic reticulum was well developed surrounding the lipid droplets, and was closely associated with the mitochondria. Preadipocytes had the typical structure of growing cells, developing long cytoplasmic processes between and around blood capillaries. Mature brown adipocytes represented the final stage of differentiation. Almost all their cellular volume was occupied by lipid droplets and numerous mitochondria with very dense cristae. Brown adipocytes were also characterized by a tight association with blood capillaries, as expected from metabolically active cells requiring oxygen and substrates. These observations provide direct ultrastructural evidence for a progressive differentiation of interstitial cells into brown adipocytes with a continuum of intermediate cellular types.