bluuebunny/crossref_metadata_2025 huggingface dataset:
Histological analysis of limb regeneration in postmetamorphic adult Ambystoma
Authors: Young Henry E. , Bailey Claudia F. , Markwald Roger R. , Dalley Bernell K.
Published: February 2005

Previous investigation into the regenerative ability of postmetamorphic adult land phase Ambystoma has revealed that (1) these species have the capacity to completely regenerate a limb, given optimal environmental conditions, and (2) the gross morphological characteristics of limb regeneration in these species compared favorably with the external regeneration morphology of aquatic phase forms. The present study concerns a histological and histochemical examination of the regenerating limb tissues and their respective extracellular and intracellular tissue matrices.

Postmetamorphic adult Ambystoma were amputated through the forearm, placed within optimal environmental conditions, and allowed to regenerate. The tissues were harvested at designated intervals after amputation and prepared for light microscopic examination. The limb tissues were assayed histologically for similarities to and differences from previously established regeneration morphologies. It was noted that specific correlations (i.e., apical epidermal cap formation, bud outgrowth and elongation, palette formation, and digit formation) existed between regeneration histologies in these species and those previously reported for the aquatic urodeles, newt, axolotl, and larval salamander. By utilizing the histological and histochemical characteristics of the tissue, the regenerate limb was divided into five tissue units: epidermal, blastemal, soft, hard, and neuro/vascular. Based on the unique morphology of their extracellular matrices and respective histochemical staining patterns, four distinct blastemal regions were delineated within the blastemal units: subregenerate epidermal blastema, soft‐tissue blastema, hard‐tissue blastema, and core blastema. Histochemically, changing patterns of highly sulfated, weakly sulfated, and carboxylated polysaccharides and glycosylated compounds were located within both the extra‐ and intracelluler stump and regenerate tissue matrices during regeneration. In addition, these patterns of intra‐ and extracellular macromolecular material correlated to previous reports of similar‐type compounds assayed during regeneration in aquatic urodeles. With this in mind, the adult land phase Ambystoma can be considered an appropriate model system for studies concerning normal limb regeneration.
Computer‐aided reconstructive morphology of the baboon abducens nucleus
Authors: Augustine James R. , Huntsberger Terrance , Moore Michael
Published: February 2005

Our previous effort at reconstructive morphology included the marriage of the horseradish perioxidase (HRP) neurohistochemical method to a Lucite plate reconstruction technique. Limitations imposed by this combination of methods has led us to develop a computer‐based system that utilizes image‐processing techniques and the data obtained from HRP processed serial light microscope sections. Labeled neurons of the baboon abducens nucleus were identified by HRP conjugated to wheat germ agglutinin. Using the resulting serial sections and a unique imaging process involving a pattern recognition algorithm, our computer‐based system automatically differentiates neuronal from nonneuronal features, delineates the surface boundaries of the neuronal population, and then assembles these serial sections into a solid three‐dimensional structure that can be rotated and further analyzed. A computer‐generated solid model of this neuronal population has been reconstructed and reproduced in a two‐dimensional publishable format. It is anticipated that with further development this system will be able to utilize data from the same specimen to study spatial relations through three‐dimensional reconstruction, as well as to study the quantitative morphology of a neuronal population. Other computer‐aided systems are noted, as are the advantages and shortcomings of the present method.
A morphometric analysis of the muscle‐tendon junction
Authors: Trotter J. A. , Hsi K. , Samora A. , Wofsy C.
Published: February 2005

Transmission of the contractile force produced by skeletal muscle fibers from myofilaments to tendon fibers occurs at the muscle‐tendon junction. This interface between muscle and tendon is characterized by an amplification of the membrane area across which force is transmitted, with the result that stress at the muscle‐tendon interface is less than it would be if the muscle fiber ended without surface folding. The amount of stress reduction is proportional to the degree of surface amplification. Because an understanding of the mechanical properties of the muscle‐tendon junction requires a quantitative appreciation of the amplification of interfacial area, and hence the reduction of stress, produced by membrane elaboration at the muscle‐tendon junction, we have developed a reliable morphometric approach for quantifying this surface amplification. The approach reported here makes use of point‐counting techniques applied to thin sections of murine muscletendon junctions, together with a statistical analysis of the data. The results indicate that the load on the cell membrane at the muscle‐tendon junction is reduced approximately 1 order of magnitude by membrane amplification, compared to the load calculated to occur if the muscle fiber ended as a right cylinder. In addition, significant differences in the degree of membrane amplification have been detected among the four muscle‐tendon junctions analyzed in this study. These results and methods should prove useful in future analyses of normal and abnormal muscle‐tendon junctions.
Characterization of conotruncal malformations following ablation of “cardiac” neural crest
Authors: Kirby Margaret L. , Turnage Kirby L. , Hays Beth M.
Published: February 2005

Neural crest cells from the cranial region of the neural fold populate the outflow tract of the developing chick heart. Removal of this region of premigratory neural crest has been shown previously to result in a high percentage of conotruncal malformations. The present study was undertaken to define more precisely the regions of premigratory neural crest which are needed for normal conotruncal development. Various regions and lengths of premigratory cranial neural crest were ablated using microcautery. Three defects in conotruncal development were significantly correlated with the neural crest ablation. These were high venticular septal defect, single outflow vessel originating from the right ventricle, and single outflow vessel overriding the ventricular septum.
The streaming submandibular gland
Authors: Zajicek G. , Yagil C. , Michaeli Y.
Published: February 2005

Twenty female young adult rats were injected with tritiated thymidine (3HTdR). The animals were then killed in groups of five, at the following times: 1 hour, and 4, 16, and 23 days. Autoradiograms of sections through the submandibular gland were prepared, and the location of labelled cells in relationship to tubuli and acini was recorded. The different tubular and acinar cross sections could be distinguished by their cell number. Narrow tubuli had fewer nuclei than the wider ones. The nuclear number of a cross section was defined as its class and the location of a labelled epithelial cell was expressed in relationship to the class where it was found. The location of a labelled stromal cell was determined by the class of its neighboring tubular or acinar cross sections. The mean cell numbers of intercalated, granular, and striated duct cross sections were, respectively, 4.7, 10.5, and 10.2, while the average cell content of acini was 4.7 cells. One hour after labelling most labelled tubular epithelial and stromal cells were found in tubular cross sections (or low tubular classes), while in the acini, labelled epithelial and stromal cells were found mainly in wider cross sections (or higher acinar classes). Within the next 23 days labelled tubular cells and stroma proceeded into higher classes, while labelled acinar epithelium and stroma cells were displaced into narrower cross sections (or lower classes). The displaced tubular epithelium and stroma covered daily 0.26 classes. At this velocity the cell will reach the highest tubular class in 62 days and the estimated maximal tubular cell life span is 62 days. Acinar epithelium and stroma were displaced at a velocity of 0.024 classes/day, and their maximal life span was 125 days. These results indicate that contrary to the accepted belief, submandibular gland epithelium and stroma are renewing cell populations. Tubular cell progenitors are formed in the intercalated duct, from which they proceed into the granular. During this journey they are accompanied by dedicated stroma cells which are displaced at the same velocity as the epithelial cell. Moreover, the data suggest that the intercalated duct supplies also acinar cell progenitors which are displaced into the acinus. Since in the submandibular gland epithelium and stroma proceed along the tubuli and acini concurrently they probably carry their microenvironment with them.
Ultrastructural cytochemistry of carbohydrates in microfibrils associated with the amorphous elastin in the monkey aorta
Authors: Baba Tooru , Takagi Minoru , Yagasaki Hiroshi
Published: February 2005

Two distinct ultrastructural components of elastic fibers can be identified–namely, the amorphous elastin and the microfibrils. We have examined the tunica adventitia of monkey aortas to demonstrate differential localization of carbohydrates in elastic fibers and collagen fibrils using Thiéry's periodic acidthiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) staining of thin sections for vicinal‐glycol‐containing complex carbohydrates, en bloc concanavalin A (Con A) staining specific for α‐D‐mannosyl and α‐D‐glucosyl groups, and en bloc wheat germ agglutinin (WGA) staining specific for N‐acetyl‐D‐glucosamine, N‐acetylneuraminic acid, and N‐acetyl‐D‐galactosamine. The PA‐TCH‐SP method moderately stained microfibrils and weakly stained collagen fibrils, but did not stain the amorphous elastin. Both Con A and WGA staining methods strongly stained microfibrils and moderately stained collagen fibrils, whereas the amorphous elastin lacked staining. Thus PA‐TCH‐SP, Con A, and WGA staining methods allow differential ultrastructural localization of carbohydrates in elastic fibers and collagen fibrils in monkey aortic adventitia and demonstrate the presence of more carbohydrate components in microfibrils than in collagen fibrils, whereas amorphous elastin lacks carbohydrate staining.
Ontogeny of small‐granule APUD cells in hamster lung: A morphological study
Authors: Sarikas Stephen N. , Hoyt Richard F. , Sorokin Sergei P.
Published: February 2005

Development of small‐granule APUD cells and cell clusters was studied in 13‐day to 15‐day fetal hamster lungs by periodic acid‐Schiff (PAS)‐lead hematoxylin staining, monoamine fluorescence, and transmission electron microscopy. We examined 11‐day and 12‐day fetal, early postnatal, and adult animals only by PAS‐lead hematoxylin. Precursors of small‐granule cells first appear as PAS‐negative clear cells in proximal airways of 13‐day lung, occurring singly or in clusters of 2–25 cells and standing out among their undifferentiated, glycogen‐laden, PAS‐positive neighbors. By 14 days, developing small‐granule cell clusters are prominent in main and lobar bronchi, extending 2–3 airway generations into the periphery. Clear‐cell clusters, similar to those seen in 13‐day lung, appear in peripheral airways and reach within one generation of developing terminal sacs. By 15 days, a few small, small‐granule cell clusters are located at bronchioloalveolar junctions. Comparatively mature clusters occur in proximal airways; they are characterized by specific formaldehyde‐induced monoamine fluorescence demonstrable after exposure in vitro to 5‐hydroxytryptophan. In early postnatal stages, PAS‐positive granules are resolvable toward the base of some endocrine cells. Ultrastructurally, pulmonary APUD cells contain numerous membrane‐limited granules (180‐nm diameter) of varying electron density. In 13‐day lung, granules sparsely populate the cytoplasm of clear cells, but as the cells mature, the granule population increases and becomes concentrated in the basal cytoplasm. Fetal development of smallgranule cells is therefore compressed into the last 4 days before birth. Most clusters appearing in neonatal lungs are not yet fully mature, and not all subtypes of this population are present until some time later.
Development of hamster tracheal epithelium: I. A quantitative morphologic study in the fetus
Authors: McDowell Elizabeth M. , Newkirk Carnell , Coleman Bill
Published: February 2005

The development of the tracheal epithelium was studied in hamsters, beginning on fetal day 10 and ending on fetal day 16, shortly after birth. The epithelial morphology was characterized and as soon as the cells could be recognized by type (day 14) their proportions were quantified along dorsal and ventral surfaces from larynx to carina. At all times, columnar cells of the dorsal surface were taller than those of the ventral surface. On days 10 and 11 the simple epithelium was composed of poorly differentiated columnar cells, but on day 12 organoid clusters, consistent with the morphology of neuroepithelial bodies, were observed; four clusters were seen along the dorsal epithelium in one section. The epithelium was pseudostratified on day 13, composed of short and columnar cells. Most columnar cells were poorly differentiated but a few preciliated and ciliated cells were recognizable dorsally, especially at the tracheal poles. Hemidesmosomes were seen at the base of some short cells on day 14, and rough endoplasmic reticulum was moderately developed in some columnar cells, suggesting that these cells were prebasal and presecretory cells, respectively. Preciliated and ciliated cells, which were most prevalent caudally, accounted for about 14% of all dorsal epithelial cells on day 14, but they were rare in the ventral surface, about 0.1%. The epithelial cells were sufficiently specialized by days 15 and 16 to allow quantification by type. Proportions of basal, presecretory, and preciliated‐ciliated cells were similar on both days but the cellular makeup of dorsal and ventral surfaces was significantly different. There were more basal cells ventrally (36–40%) than dorsally (22–23%), and more preciliated‐ciliated cells dorsally (18–21%) than ventrally (about 1%). On days 15 and 16 differences also existed along both surfaces between cranial and caudal parts of the trachea. Basal cells were more prevalent cranially and preciliated‐ciliated cells were more prevalent caudally.
A mathematical method for estimating paired testes weight from in situ testicular measurements in three species of hamster
Authors: Watson‐Whitmyre Marcia , Stetson Milton H.
Published: February 2005

Linear regression analysis was used to determine the correlation between testicular volume (calculated from measurements of length and width) and weights of paired testes. Line equations that can be used to predict weights of paired testes from the volume of one or both testes are given for three species of hamster (Mesocricetus auratus, Mesocricetus brandti, and Phodopus sungorus sungorus). Because these parameters are highly correlated (r ≥ 0.97), the line equations provide a highly reliable means of estimating weights of paired testes from in situ surgical measurements. Weights of testes predicted in this manner are highly correlated with actual weights of paired testes (r ≥ 0.96). The surgical method for measurement of the gonads is also described. This technique for estimating paired testicular weight allows considerable reduction in the number of animals required for longterm experiments and also permits longitudinal studies of individual animals.
The sinus of the dorsum sellae
Authors: Schnitzlein H. N. , Murtagh F. Reed , Arrington John A. , Parkinson Dwight
Published: February 2005

Dissections of cadaver heads and studies of specimens sectioned in horizontal (axial), coronal, or sagittal planes at low (5×) magnification revealed a frequent venous sinus within the bone of the dorsum sellae in addition to the true dural sinuses. This sinus interconnected the cavernous sinuses on either side of the sella turcica and was continuous with the superior and inferior petrosal sinuses and the basilar plexus. The sinus was quite evident on venograms of five patients. In sagittal sections of 37 adult cadaver heads, the sinus was identified in 28 (76%) and was absent in nine (24%) in which there was pneumatization of the dorsum sellae by the sphenoid sinus. The intracranial sinus of the dorsum sellae is not a true dural sinus but is comparable to the basivertebral veins of the spine.
Plasma membrane reregionalization in cultured mouse hepatocytes
Authors: Watanabe Jun , Kanamura Shinsuke , Kanai Kazuo
Published: February 2005

The cytochemical localization of alkaline phophatase (ALPase) activity and the autoradiographic distribution of glucagon receptors were examined in the plasma membrane of cultured mouse hepatocytes. After 24 hours of culture, ALPase activity was exclusively localized on the plasma membrane in areas of cell‐cell contact, and glucagon receptors were more numerous in the plasma membrane at the periphery of re‐formed cell trabeculae. These results indicate that plasma membrane regionalization of hepatocytes, lost by cell isolation, reappeared during culture. The cells maintained this plasma membrane regionalization until 48 hours of culture. By 72 hours of culture, however, ALPase activity was seen on the external surface of all regions of plasma membrane, and the glucagon receptors decreased markedly in number and became scattered in all regions of plasma membrane. Thus, the re‐formed plasma membrane regionalization disappeared in the cells by 72 hours of culture.
The effects of vagotomy on compensatory ovarian hypertrophy and follicular activation after unilateral ovariectomy
Authors: Burden Hubert W. , Lawrence Irvin E. , Smith Carlton P. , Hoffman Jeanne , Leonard Marilyn , Fletcher Donald J. , Hodson Charles A.
Published: February 2005

Following unilateral ovariectomy in the rat, the remaining ovary undergoes rapid compensatory changes including an increase in the number of antral follicles (follicular activation) and an increase in ovarian weight (compensatory ovarian hypertrophy). The ovary is innervated by the vagus nerve (Burden et al., 1983). In the present study, the effects of right and left cervical vagotomy and abdominal vagotomy on follicular activation and compensatory ovarian hypertrophy in the remaining right or left ovary were compared 15 days after unilateral ovariectomy. Neither right nor left cervical vagotomy affected compensatory ovarian hypertrophy of the right or left ovaries but abdominal vagotomy depressed compensatory ovarian hypertrophy in both the right and left ovaries. Left cervical vagotomy did not inhibit follicular activation, but right cervical vagotomy prevented follicular activation in the right but not left ovary. Also, abdominal vagotomy inhibited follicular activation in the right but not the left ovary. In animals with both ovaries which were subjected to the left or right cervical vagotomy or abdominal vagotomy follicular counts in both right and left ovaries were similar. Collectively, these data indicate that the vagus nerve participates in follicular activation after unilateral ovariectomy. The data also indicate that the right ovary is more dependent on vagal influences for follicular activation than the left ovary.
Sialographic investigations on the anatomy of mouse parotid glands
Authors: Omon Masaharu , Shiga Yasuaki
Published: February 2005

The anatomic structure of the mouse parotid gland was investigated by a sialographic method. The mouse parotid was infused with 0.4–0.6 μm grains of barium sulfate sol as an x‐ray contrast medium and extirpated. The excised gland was flattened and imaged by using 10 or 25 kVp x‐rays. Twelve different strains of male mice 12 weeks old were investigated. It was found that the mouse parotid gland has the club‐shaped major lobe and the accessory lobe and that the major lobe is further divided into three lobes: the superior lobe which extends underneath the ear, the middle lobe, and the inferior lobe which extends toward the submandibular gland. The accessory lobe began from the proximal part of Stensen's duct and extended to underneath the eye. The presence of the accessory lobe, the shape of the major lobe, and the branching pattern of the parotid duct tree were mouse strain dependent.
Immunofluorescence antigen localization on boar sperm plasma membranes: Monoclonal antibodies reveal apparent new domains and apparent redistribution of surface antigens during sperm maturation and at ejaculation
Authors: Saxena N. K. , Russell L. D. , Saxena N. , Peterson R. N.
Published: February 2005

Purified boar sperm plasma membranes (PM) and PM proteins were used as antigens to produce 58 monoclonal antibodies against surface antigens. Fluorescence labelling (biotin‐avidin‐FITC) was used to determine the distribution of antigens in caput and cauda epididymal and in ejaculated spermatozoa with hybridoma supernatants and/or 1:100 diluted ascites fluid after subcloning. Sixteen areas (subdomains) of apparent restricted antigen mobility were identified and significant differences in the localization of most antigens in caput, cauda, and ejaculated PM were recognized. While localization patterns were highly reproducible with a given protocol for sample preparation and immunolabelling, localization patterns were markedly affected by changes in protocols. Fluorescence patterns were affected by the manner in which sperm were labelled (live sperm or sperm labelled at various steps), by washing, and by temperature or by addition of seminal plasma. These results indicate that the dynamic properties of the sperm PM or the surrounding fluids can easily mask or unmask or reconfigure binding sites for highly site‐specific monoclonal antibodies and that antigen distribution is probably underestimated when these labelling techniques are used. Such changes in the accessibility of antigenic sites to monoclonal antibodies limited determining the extent of distribution of a given antigen on epididymal sperm. However, the reproducibility of patterns when a given protocol is used and the large number of antibodies (39/42) displaying marked differences in localization on caput, cauda, and ejaculated PM suggest that changes in the organization of the PM constituents, whether by addition or subtraction of antigen or through configurational changes in proteins, are a major consequence of sperm maturation in the epididymis.
The development of the ovine small intestine
Authors: Trahair Jeff , Robinson Peter
Published: February 2005

Intestinal development was noted from 27 days gestation. By 50 days gestation the ovine small intestine shows the beginnings of villus formation. The lumen becomes patent by 70 days. Proximal regions mature earlier than distal regions. Vacuolation of enterocytes occurs in all regions of the small intestine at some stage during development. Mature‐looking enterocytes can be found in proximal regions by 125 days gestation while in distal regions immature vacuolated cells can still be found just prior to birth. Enterocytes lining the villi are more mature at the villus tip than those at the base in all regions. This gradient of maturation is consistent with a suggestion of the early establishment of adult patterns of proliferation and migration of enterocytes in the sheep fetus.
Testicular histology in streptozotocin‐induced diabetes
Authors: Anderson Judy E. , Thliveris James A.
Published: February 2005

The use of the streptozotocin rat model for diabetes has been questioned by the appearance of extrapancreatic cytotoxicity, notably renal and hepatic. In this study the model was made specific to diabetic, drug‐induced, and starvation effects n parameters of testicular histology. Formulation of orthogonal contrast expressions permitted the statistical separation of these influences. Tubules from moderately diabetic animals showed frequent thinning, and permature desquamation of pachytene spermatocytes and early spermatids from the germinal epithelium. Results showed that only diabetes significantly decreased seminiferous tubule diameter and increased testicular blood vessel numbers. In addition, significant alteration from the control pattern of tubule stage distribution was noted, particularly at stages IX–XI. Due to the inclusion of a drug‐treated but nondiabetic group, streptozotocin itself was shown to have no significant effect on these parameters.
Effect of carrageenan on the histology of the bursa of fabricius and the humoral immune response to SalmonellaO antigen
Authors: Olah Imré , Glick Bruce
Published: February 2005

Bursal secretory cells have been studied with light and electron microscope after prolonged carrageenan treatment. Intravenous injected carrageenan decreased the number of secretory cells as early as 4 days after the first carrageenan administration. Degranulation of the secretory cells may have made it difficult to identify these cells. The discharge of granules from the secretory cells was indicated by the appearance of a large amount of extracellular substance on the cell surface. The carrageenan may have accelerated the IgM‐IgG switch after immunization with SalmonellaO antigen. The rapid IgM‐IgG switch was preceded by degranulations of the secretory cells. Therefore, the secretory products of the cells might have contributed to the switch. The number of secretory cells in the carrageenan‐treated birds increased by the secondary immunization. Many of these secretory cells were immature and located close to the corticomedullary border. The young cells revealed a large blastlike nucleus and bulky cytoplasm with granules surrounding the cytocentrum and Golgi zone.
Unusual variation of the arterial pattern of the human upper limb
Authors: Jurjus Abdo , Sfeir R. , Bezirdjian R.
Published: February 2005

The anomalous brachial artery, after giving off a profunda brachii artery with no collaterals, divides in its upper one‐third into two equal‐sized arteries, brachial arteries #1 and 2. These arteries lie next to each other in the normal path of the brachial artery. Brachial arteriy #1 is possibly a high‐origin and persisting radial artery. It gives no collaterals in the arm. At the cubital fossa, it becomes subcutaneous and divides into two equal‐sized radial and ulnar arteries. These arteries run completely superficial to flexor muscles of the forearm and are terminated by branches running above the thenar and hypothenar eminences, respectively. Brachial artery #2 is possibly a high‐origin artery of the common interosseous. The course of this artery resembles the course of the brachial axial artery of the embryo. It supplies the anterior compartment of brachial muscles and continues as the common interosseous artery. This common interosseous artery in turn branches into the superior and inferior ulnar collaterals, and the anterior and posterior intersossei. It does not regress, but has a major role in forming the deep palmar arterial arch in the hand. The clinical implications of such an anomaly are discussed.
Antigenic phenotyping of isolated and in situ rodent follicular dendritic cells (FDC) with emphasis on the ultrastructural demonstration of Ia antigens
Authors: Kosco Marie H. , Tew John G. , Szakal Andras K.
Published: February 2005

The antigenic phenotype of mouse lymph node follicular dendritic cells (FDCs) was studied by immunocytochemical techniques. Indirect fluorescence was used in conjunction with monoclonal antibodies to localize FDC surface antigens on FDC‐enriched cell preparations and in cryostat sections. Lymph nodes from rats and mice were also labeled directly for Ia antigens with fluorescein‐ or peroxidase‐conjugated Ia‐specific monoclonal antibodies (i.e., MRC Ox4 and 10‐2.16, respectively). Lymphoid tissue was also prepared for electron microscopy to allow clear distinction between Ia antigens of B lymphocytes and FDCs in situ. In these experiments, gold‐labeled antigen was used to clearly identify FDCs and their processes among the Ia‐positive cells of lymph node follicles. The labeling observed by light and electron microscopy showed that FDCs expressed Ia in situ and in vitro. Additional surface determinants shown to be expressed by FDCs included H2‐K, common leukocyte antigen, and the receptor for the Fc portion of IgG1 and IgG2b. Neither macrophage antigens, such as Mac‐1, Mac‐2, Mac‐3, and F4/80, nor the lymphocyte markers Ly‐1, Ly‐2, and Thy‐1 were expressed by FDCs. Thus, the antigenic phenotype of FDCs, along with their distinctive dendritic morphology, their nonphagocytic and nonadherent nature, and their ability to trap and retain immune complexes on their plasma membrane, identifies them as a unique cell population.
Demonstration of a catecholaminergic innervation in human perirenal brown adipose tissue at various ages in the adult
Authors: Lever Jeffrey D. , Jung Roland T. , Nnodim Joseph O. , Leslie Peter J. , Symons Deborah
Published: February 2005

From light and electron microscopic studies on perirenal fat from human donors 27, 39, and 47 years old, unequivocal evidence is found for the presence of islands of multilocular adipocytes. After glyoxylic acid condensation for visualisation of biogenic amines, catecholaminergic nerve plexuses were demonstrated around the arteries of supply to these islands and within the intercellular spaces between their constituent adipocytes. Transmission electron microscopy revealed the cytology of these adipocytes to be similar to that of brown adipocytes in rodents. These findings are viewed in the light of a possible energetic potential for brown adipose tissue in the human adult.
Development of the apical ectodermal ridge in the chick leg bud and a comparison with the wing bud
Authors: Todt William L. , Fallon John F.
Published: February 2005

Histologic examination of the leg bud of stage‐18 to stage‐23 chick embryos was carried out with special reference to the development of the apical ectodermal ridge. The leg bud apical ectoderm, initially an irregular columnar epithelium with an overlying simple squamous periderm, began to thicken during stage 18 and was a pseudostratified epithelium by stage 19. A notch in the base of the thickened ectoderm was seen as early as stage 19. The notch represented the cross‐sectional view of a groove, which developed in the base of the ridge. As development proceeded, the ridge and its associated groove lengthened. In addition, the groove became more prominent, and irregularities were seen in its width and depth along the apex. Ectodermal cell death was not consistently seen until stage 21 at which time most of the length of the thickened ectoderm had evidence of necrosis. Development of the leg bud ridge and wing bud ridge were compared. The temporal sequence of ectodermal thickening and ridge development was very similar in both the leg and wing buds with one exception; namely, that leg bud ridge development preceded wing bud ridge development by several hours. In addition, ectodermal cell death was not evident until stage 20 in the leg bud ridge, but could be seen at late stage 18 in the wing bud apical ectoderm. However, by stage 21, cell death was associated with most of the ridge in both the wing and leg buds. Finally, with respect to the axial line, the ridge with its associated groove extended further preaxially in the leg bud than in the wing bud, making the leg bud ridge more symmetrical.
Osteodentin formation in rat incisor as visualized by radioautography after 3H‐proline administration
Authors: Karim A. C. , Pylypas S. P.
Published: February 2005

Osteodentin formation was studied in rat incisor pulp after adriamycin administration. Male Sprague Dawley rats (100 ± 5 gm) were injected intravenously with adriamycin (5 mg/kg body weight), and after 7 days they were again injected intravenously with 3H‐proline (3 μCi/gm). These animals were killed in groups of three from 5 minutes to 4 hours after proline injection by perfusion with 3% phosphate‐buffered formaldehyde followed by 2.5% phosphate‐buffered glutaraldehyde. Control animals injected with only physiological saline, and 7 days later with 3H‐proline (3 μCi/gm), and were killed at the same time intervals. Radioautography on sections showing osteodentin formation revealed that at 5 minutes after 3H‐proline injection the labeling was located over the cells associated with the osteodentin matrix. At 1 hour after injection the labeling was located over the cells and the matrix, while at 4 hours the labeling was seen only over the matrix. It therefore appears that at least a proline‐containing component of the osteodentin matrix is synthesized and secreted by the cells associated with it.
Endocytic traffic in trophectoderm and polarised blastomeres of the mouse preimplantation embryo
Authors: Fleming Tom P. , Goodall Harry
Published: February 2005

Endocytosis from apical and basolateral cell membranes of mouse blastocyst trophectoderm was examined morphologically by using unconjugated horseradish peroxidase (HRP, fluid phase marker), cationized ferritin (membrane marker, bound ionically), and protein A‐HRP conjugate (membrane marker, identifying antigens recognised by antimouse species serum). The markers were applied in single and double labelling procedures designed to reveal the derivation, sorting site, and fate of all the major endocytic pathways. Endocytosis at the apical surface led to the obligate fusion of labelled elements with prelysosomal endosomes prior to the redistribution of membrane into lysosomal, transcellular, or recycling pathways, and to the passage of internalised fluid into lysosomes only. Complementary routes appear to operate following endocytosis at the basolateral domain. Thus, endocytic trafficking within the trophectoderm, regulated by “sorting” mechanisms localised at the endosome compartment, may be responsible for the maintenance of polarised membrane domains. The polarised transcellular pathway involving obligatory endosome fusion is present in cleavage‐stage, peripheral 16‐cell blastomeres prior to zonular tight junction formation. Nocodazole treatment to depolymerise microtubules in many cases induced a bypass of the endosomal sorting compartment during transcytosis, indicating that microtubules contribute to the spatial organization of endocytic membrane traffic.
Strategies of hemopoietic stress adaptation within the medullary cavity
Authors: Giuliani Dennis C. , Hall James C. , Morse Bernard S.
Published: February 2005

Gravimetric determination of total bone water space was used as an index of available bone marrow space in mice following various specific stressors, i.e., splenectomy, hypoxia, bone fracture, and estrone‐induced osteosclerosis. Data was corrected for bone weight and was reported as specific bone marrow volume (total bone water space/mg dry bone × 100).

A direct relationship was observed between specific bone marrow volume and medullary hemopoietic activity induced by stress. Absolute and/or relative marrow space increased following splenectomy, hypoxia, and fracture. Osteosclerotic animals shift most hemopoietic activity from marrow to spleen, and splenectomized osteosclerotic animals become anemic. Both intact and splenectomized hypoxic animals develop increased specific bone marrow volume and successfully compensate for hypoxia with enhanced erythropoiesis. Animals sustaining a fracture callus increase both specific bone marrow volume and hemopoietic activity at the callus without an increase in hemopoietic demand.

Increased specific bone marrow volume extends the marrow bone interface, where primitive stem cells accumulate, while expanding marrow stromal space, where stem cells lodge, proliferate and differentiate. Therefore, it would appear that availability of competent marrow space may play an integral part in passively permitting hematopoiesis and in determining hemopoietic reserve capacity.

Stem cell migration increases during intensified hemopoietic demand, which also may be related to available marrow space. Mice have a low medullary hemopoietic reserve capacity; subsequently, when available medullary hematopoietic stroma becomes occupied, stem cells are more likely to migrate from the marrow to extra‐medullary sites where they mature before entering the circulating pool.
Structure of the upper teeth of the filefish, Stephanolepis cirrhifer
Authors: Uehara Kiyoko , Miyoshi Sakuichiro
Published: February 2005

The teeth of the filefish were investigated with light and scanning electron microscopy. Anterior and posterior rows of pleurodont teeth are present in the maxilla. The teeth in the anterior row possess a large labial and small lingual surface and the teeth in the posterior row possess a small labial and large lingual surface. The enameloid consists of three layers–the outer, middle, and inner layer. The outer layer consists of fine, parallel crystallites oriented perpendicular to the surface. They are similar to the crystallites in enamel derived from ectoderm. In the middle layer the crystallites form parallel bundles that are oriented in the same direction as that of the crystallites in the outer layer. In the inner layer bundles of crystallites interlace with each other. The tubular structures and the terminal branches of the dentinal tubules are located among the crystallites in the inner layer. In the dentine numerous dentinal tubules radiate from the pulp cavity toward the periphery and are seen to curve slightly in an S‐shaped course. At the occlusal tip the alternating parabolic layers are seen and these are considered to be mineralized lines. The openings of the dentinal tubules are round or oval, surrounded by interlacing fibrils. The teeth are tightly fixed to the jawbone by bundles of fibrils. At the lower part of the lingual surface of the teeth in the anterior row and the labial surface of the teeth in the posterior row the bundles of fibrils start at the dentine and some fibrils run through connective tissue, while others terminate in projections of the jawbones. These structures are discussed in comparison with those of other species.
Development of specific antibody‐forming cells in various lymphoid organs of rabbit after intravenous antigen administration
Authors: van der Brugge‐Gamelkoorn Gerda J. , Kors Nel , van Rooijen Nico
Published: February 2005

Rabbits were intravenously primed and boosted with trinitrophenyl‐keyhole limpet hemocyanin (TNP‐KLH) and human serum albumin (HSA); both antigens were injected simultaneously. The localization of anti‐TNP‐antibodyforming cells (AFCs) and anti‐HSA‐AFCs was determined in various lymphoid organs of the rabbit.

In all lymphoid organs of primed rabbits anti‐TNP‐AFCs outnumbered anti‐HSA‐AFCs, with the exception of the thymus, in which neither of them was encountered. In the spleen the antibody‐forming cells were mainly situated in the periphery of the periarteriolar lymphocyte sheaths (PALS) and in the coaxial sheaths of lymphoid tissue surrounding the terminal arterioles. In the lymphoepithelial organs AFCs were almost exclusively situated in the interfollicular areas, and in the lymph nodes largely in the medulla.

An intravenous booster injection led to a secondary immune response (i.e., increase of AFCs) in the spleen. No visible change in the number of specific AFCs was observed in the lymphoepithelial organs. However, in the mesenteric and popliteal lymph node the number of anti‐TNP‐AFCs had increased tremendously.
The influence of vasovasostomy on testicular alterations after vasectomy in Lewis rats
Authors: Flickinger Charles J. , Herr John C. , Howards Stuart S. , Caloras Daniel , Yarbro E. Scott , Spell Donald R. , Gallien Thomas N.
Published: February 2005

The occurrence of alterations in testicular weight and morphology after vasectomy and vasectomy reversal by vasovasostomy was studied in Lewis rats. Animals were studied 3, 4, and 7 months after bilateral vasectomy or a vasectomy followed 3 months later by vasovasostomy. Other rats served as shamoperated controls. The weights of the testes in vasectomy and vasovasostomy animals fell into two groups—small testes weighing less than 0.88 g and normal‐sized testes of 1.2 g or more. When the extent of testicular alterations was estimated in sections for light microscopy by use of a semiquantitative testicular biopsy score count (TBSC), the morphology of the testes corresponded closely to the testis weight (r = .94), small testes having correspondingly low TBSC scores. In severely altered small testes, the seminiferous tubules were narrower than in sham‐operated rats, and numbers of germ cells were greatly depleted. Many tubules contained only Sertoli cells and spermatogonia, although spermatocytes were present in a minority of tubules. A few seminiferous tubules contained multinucleate spermatids. Electron microscopy of severely altered tubules revealed closely apposed processes of Sertoli cells, which contained filaments, microtubules, and endoplasmic reticulum. In contrast, testes with normal weight in vasectomy and vasovasostomy groups resembled those of the sham‐operated animals. Comparison of distributions of testicular biopsy score counts demonstrated differences between vasectomy and vasovasostomy groups as time after operation increased. At the 3–4‐month intervals, approximately one‐third of the testes were severely altered in both vasectomy and vasovasostomy groups. However, by 7 months the proportion of altered testes progressed to 60% in animals with a vasectomy, while it remained similar to the earlier intervals in rats that had received a vasovasostomy. These results suggest that vasovasostomy may prevent the progression of testicular alterations that occur after vasectomy, but vasovasostomy does not appear effective in reversing testicular changes.
Retinal cell death occurs in the absence of retinal disc invagination: Experimental evidence in papaverine‐treated chicken embryos
Authors: García‐Porrero Juan A. , Colvee Elvira , Ojeda Jose L.
Published: February 2005

In an attempt to clarify the relationship between the presence of retinal cell death and the invagination of the optic vesicle, we have tested the occurrence and cytological characteristics of the retinal necrotic areas in the embryonic chicken after the administration in ovo of papaverine. Papaverine, a Ca2+ antagonist, was found to prevent the invagination of the optic vesicle. All embryonic retinae presented two distinct necrotic areas. However, these areas of cell death appeared abnormally located in the experimental, uninvaginated retina. One area was located at the transition between the retinal disc and the ventral wall of the optic vesicle; a second area was located in the dorsal wall of the optic vesicle, close to the optic stalk. We suggest that these necrotic areas represent the normal necrotic areas, should the invagination of the retinal disc have taken place. Retinal cell death appears to beprogrammed; it occurs whether the retinal disc invaginates or not. Cell death appears, in this experimental model, as a natural marker giving evidence that the embryonic retinal cells move from the optic stalk into the invagination retinal disc during normal eye cup formation.

In addition to the uninvaginated optic vesicle the lens placode failed to invaginate in 45% of the cases, forming a lens vesicle in 55% of the remaining cases. This suggests that the two processes of invaginate in 45% of the cases, forming a lens vesicle in 55% of the remaining cases. This suggests that the two processes of invagination are governed by a different set of factors.
Thin collagenous septa in cardiac muscle
Authors: Dolber Paul C. , Spach Madison S.
Published: February 2005

Light and electron microscopy were used to study the structure and distribution of thin collagenous septa (sheets) in dog and rabbit cardiac muscle to determine whether they, like thick collagenous septa, could affect electrical impulse propagation. Generally, thin septa (0.2–0.5 μm) ensheathed myocytes or groups of myocytes for short distances and thicker septa partially or completely ensheathed groups of myocytes for long distances (up to several mm); together, thin, and thick septa divided the myocardial mass into myocyte cords (funicles) of 10–30 μm diameter. Septal architecture varied not only between regions and within regions at different ages but also within single bundles, precluding the assumption that the architecture found in one bundle can be applied to another. Electron microscopy demonstrated that thick septa consisted of many tightly packed collagen fibrils, often with distinct layers running at different angles; thin septa consisting largely of circumferential collagen fibrils. Thin septa in dog ventricular papillary muscle generally contained few and widely spaced collagen fibrils, whereas thin septa in dog atrial Bachmann's bundle contained tightly packed collagen fibrils. In either site, thin septa were rarely breached by nexuses and thus marked sites where lateral intercellular electrical coupling was unlikely. Serial 7 μm cross sections of dog Bachmann's bundle stained by a modification of the picrosirius red technique showed that thin septa sometimes persisted uninterrupted over several myocyte lengths. The results provide evidence that thin septa comprimised of tightly packed collagen fibrils may significantly modify impulse propagation transverse to the longitudinal axis of the myocytes.
Morphology and endocrine production of cells in the islets of langerhans of the Chacma baboon
Authors: Wolfe‐Coote Sonia A. , du Toit D. F.
Published: February 2005

Biopsies of the pancreas head, tail, and uncinate regions of 6 Chacma baboons (Papio ursinus) were processed for ultrastructural and immunocytochemical (ICC) studies using avidin‐biotin peroxidase label for light microscopy (LM) and immunogold for electron microscopy (EM). Survey 0.5 μm sections of Spurrs resin embedded tissue revealed areas of suitable islets. Thin 100‐nm sections were then cut and stained from the osmicated blocks for ultrastructural studies. For ICC investigations, 1 μm sections were immunolabeled for LM before areas were selected for thin sectioning for ultrastructural immunolabeling.

The baboon endocrine pancreas ultrastructure was found to be similar to that of other mammals with minor differences in islet and secretory granule size and shape and in electron opacity of the secretory granule cores. Insulin glucagon, somatostatin and pancreatic polypeptide (PP) producing cells were described. A small number of cells were seen to contain both glucagon and PP and some D cells were observed to contain a few granules with both the appearance and immunoreactivity of A cell secretory granules.

Statistical analysis of 100 secretory granule diameters of each of the 4 cell types in 6 baboons revealed significant differences (p < 0.001) in size between all but those of the A and D cells.

The insulin precursor subunit, C‐peptide, and the glucagon precursor, glicentin, were each found together with the final hormone product in their respective secretory granules. The precursors were often located toward the periphery of the secretory granule, suggesting that the conversion of precursor to active hormone may be membrane associated.

A nonrandom topographical association was observed between A and D cells, suggesting a strong functional implication.