bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitochondrial alterations in embryos exposed to B‐hydroxybutyrate in whole embryo culture
Authors: Horton W. E. , Sadler T. W.
Published: February 2005

The ketone body B‐hydroxybutyrate (B‐OHB) produces malformations and ultrastructural alterations in mitochondria of mouse embryos exposed for 24 hours to the compound in whole embryo culture. The present study was conducted to establish the time‐course of the mitochondrial changes to determine whether the changes are reversible, and to relate these changes to the malformations produced by the compound. Since mitochondria also play a key role in the metabolism of ketone bodies, the capacity of the early somite embryo to metabolize B‐OHB was investigated in an effort to link the morphological alterations in the mitochondria to a biochemical process. Early somite embryos were cultured 4, 8, or 24 hours in the presence of 32 mM DL‐B‐OHB and then cultured for an additional 24 hours in control serum. Finally, embryonic tissue during the teratogenic period was assessed for its capability to oxidize B‐OHB using D‐(3‐14C)‐B‐OHB. The treated embryos showed progressive alterations in the mitochondria, beginning at 4 hours with a loss of matrix density and culminating at 24 hours with high‐amplitude swelling, complete loss of matrix density, and disappearance of cristae. These alterations were reversible following removal of the embryos after 24 hours of exposure to B‐OHB and culturing for an additional 24 hours in control serum. Metabolism studies demonstrated that the early somite embryo possesses a limited capacity to oxidatively metabolize B‐OHB. The biochemical implications of these findings are discussed with respect to the possible role of ketone bodies in the mechanism of diabetes‐induced congenital malformations.
Bone lining cells and hematopoiesis: An electron microscopic study of canine bone marrow
Authors: Deldar Ahmed , Weiss Leon , Lewis Hugh
Published: February 2005

Hematopoietic bone marrow in the dog is enclosed by a nearly complete and rather complex layer of endosteum, consisting of a diverse group of cells collectively called bone lining cells (BLC). Cell types comprising BLC include osteoblasts and osteoclasts, and other cell types, among which are elongated, flat cells with a spindle‐shaped nucleus, and small cytoplasmic vesicles. The composition and thickness of the layer of BLC varies along the perimeter of the marrow. The layer may be simple or stratified. Occasionally a zone of tightly packed regularly arranged collagenous fibers lies between the bone lining cells and bone. Hematopoiesis, particularly neutrophilic, often occurs in the bone marrow next to the BLC. Cytoplasmic processes of BLC occasionally extend into the hematopoietic spaces and stromal cells in the hematopoietic compartment may extend processes to the layer of BLC. Occasionally cells of the BLC are similar in appearance to stromal cells within the marrow. Our observations together with the experimental findings of others (that fibroblastic stromal cells contribute to the hematopoietic inductive microenvironment, that hematopoietic stem cells are concentrated subosteally, that cells responsible for regeneration of the marrow stroma are derived from the endosteal layer, and that high concentrations of hematopoietic colony‐stimulating factors are produced there) indicate that the hematopoietic capacities of bone marrow may be regulated by BLC.
Morphometric analysis of the nucleolus during the life cycle of human odontoblasts
Authors: Couve Eduardo
Published: February 2005

Developing first premolars were used as a model system to obtain information on the nucleolar structure of human odontoblasts at several stages of their life cycle. Four stages were defined by their location within the tooth: (a) preodontoblasts were located at the growing tip of the root; (b) secretory odontoblasts in the apical region; (c) transitional odontoblasts in the middle region; and (d) aged odontoblasts in the coronal region. Preodontoblasts have a small nucleolus (0.55 μm2) with few strands of dense fibrillar material radiating from the fibrillar center. Secretory odontoblasts are characterized by a large (1.24 μm2), irregular, and reticulated nucleolus. The fibrillogranular material, the largest component in all nucleoli, reaches maximal size at this stage (0.88 μm2). Fibrillar centers occupy about the same area (0.1 μm2) throughout the odontoblast's life cycle. As the formation of primary dentin is completed, the nucleolus of transitional odontoblasts is reduced in size (0.54 μm2). Finally, the aged odontoblasts have a small, compact nucleolus (0.39 μm2), with segregated components. Morphologic analysis and quantification of size and component areas of nucleoli obtained with an image analyzer indicated that secretory odontoblasts had the most active, and aged odontoblasts the least active, nucleolus.
Development of hamster tracheal epithelium: III. Illustration of statistical methods for proportional data in biology
Authors: Coleman Bill , McDowell Elizabeth M.
Published: February 2005

The data in the two companion papers (McDowell et al., 1985a,b) are of a commonly occurring type in which the dependent variable takes on one of a small number of distinct values; we wish to compare the relative proportions in which these values occur. Student's t test is inapplicable. We explain here in detail the linear logistic model that is appropriate, using our data as an example.

Several reasonable models must first be fit. We did this by the maximum likelihood method, using a computer. We then used a x2 test to decide statistically between models. This process amounts to deciding directly which of the independent variables are important in determining the outcome, and thus it is the center of physiologic interest.

The outcome depends on the initial choice of parameterization of the model. Generalizations are required in more complicated, but still commonly occurring, types of data.
Localization and development of immunoreactive triiodothyronine in thyroid glands of dogs and chickens
Authors: Kameda Yoko , Udatsu Kyoko , Horino Masaharu , Tagawa Takasuke
Published: February 2005

The localization of immunoreactive T3 was investigated in dog and chick thyroid glands either fixed in Bouin's solution or freeze‐dried and fixed with paraformaldehyde vapor, and compared with localization of 19S‐thyroglobulin. Freeze‐drying followed by paraformaldehyde vapor was better for the demonstration of T3 than Bouin's solution; it gave a much stronger immunoreactivity for T3. This fixative was also excellent for the demonstration of thyroglobulin. The immunoreactive T3 was detected only in the colloid and was never observed in the follicular cells, although immunoreactive thyroglobulin was present not only in the colloid but also in the follicular cells. Subsequently, in dog fetuses and chick embryos the appearance and development of immunoreactive T3 were studied. At 40 days of gestation in dog fetuses and at 9 days of egg incubation in chick embryos, immunoreactive T3 was found in the colloid of primordial follicles coinciding with the formation of the colloid. The ability of embryonic thyroid glands to synthesize T3 seems to be linked to the organization of follicles. With progressing development, the follicles stored more colloid and immunoreactive T3 within the follicular lumina. Concentrations of immunoreactive T3 in thyroids from chickens at various stages of development were also studied by radioimmunoassay. The T3 concentration was first detected at 9 days of incubation and gradually increased with embryo age; it was related to the amounts of colloid stored in the follicles.
The sensory innervation of the rat rhinarium
Authors: Silverman Richard T. , Munger Bryce L. , Halata Zdenek
Published: February 2005

The present study documents the characteristics of innervation of the rhinarium or hairless rat snout skin by light and electron microscopy. The outer glabrous surface is covered with a stratified squamous epithelium that forms both rete pegs and rete ridges, the latter on the inferior border near the philtrum. The glabrous skin contains numerous presumptive epidermal and dermal free nerve endings (FNE's), Merkel terminals at the base of the rete ridges and pegs, and simple, nonencapsulated corpuscles. A second region of dense innervation, found on an elevation of the inner wall of the vestibule, contains similar components of innervation, with the exception that no Merkel terminals were identified. Since no Merkel terminals were present in this area of the vestibule, intraepidermal as well as dermal FNE's could be identified with certainty. This skin is covered by a thin squamous epithelium overlying dense connective tissue. The simple corpuscles are similar to those in the rhinarium, as well as resembling those described in other species. FNE's were frequently observed intimately associated with simple corpuscles. Several examples of large FNE's with two to three layers of cytoplasmic lamellae were found, suggestive of transitional forms between FNE's and simple corpuscles.

Thus, the pattern of sensory innervation in the glabrous rat snout skin is similar to that found in other furred species described to date, but in addition, the sensory innervation of ridged skin in the rat also resembles that of epidermis organized into rete pegs. This dense sensory innervation may be correlated with whisking behavior of the predominately nocturnal rat.
The ontogeny of nexuses (gap junctions) in the ovary of the fetal mouse
Authors: Mitchell Philip A. , Burghardt Robert C.
Published: February 2005

Nexuses (gap junctions), the morphological correlates of direct cell‐to‐cell communication, were consistently detected between granulosa cells of primordial follicles in the ovaries of adult cycling, juvenile, or neonatal mice. To examine the ontogeny of these intercellular channels, the cellular interactions occurring during the fetal stages of folliculogenesis, which culminate in the formation of primordial follicles, were analyzed in ovaries from fetal days 13, 15, 17, and 19. On fetal day 13, the ovary is characterized by clusters of germinal cells and invading rete ovarii cells. The rete cells progressively penetrate the ovary and wall off clusters of oocytes by fetal day 17, at which time rete cells can be recognized as presumptive granulosa cells. Gap junctional contacts can be recognized between rete cells on day 13 and these contacts persist as the cells become recognizable as presumptive granulosa cells throughout ovarian histogenesis. Quantification of junctional contacts from days 15–19 indicated that the number of gap junctions increases with fetal age. In addition heterocellular gap junctional contacts were detected between oocytes and presumptive granulosa cells as early as fetal day 17, indicating that the potential for direct intercellular communication between granulosa cells and oocytes is established from the earliest contact.
Differentiation kinetics of osteoclasts in the periosteum of embryonic bones in vivo and in vitro
Authors: Scheven Ben A. A. , Kawilarang‐De Haas Elisabeth W. M. , Wassenaar Anne‐Marie , Nijweide Peter J.
Published: February 2005

Osteoclast progenitors are seeded via the blood stream in the mesenchyme surrounding embryonic long bone models long before the appearance of multinucleated osteoclasts. The proliferation and differentiation of these progenitors in embryonic mouse metatarsal bones was studied with acid phosphatase (AcP) histochemistry and 3H‐thymidine autoradiography.

In vivo, tartrate‐resistant, acid phosphatase‐positive, mononuclear cells appear in the periosteum (AcPP‐P cells) at the age of 17 days (after conception). On day 18, AcP‐positive, multinucleated osteoclasts invade the bone rudiment and start resorbing the calcified cartilage matrix, resulting in the formation of the marrow cavity.

The kinetics of osteoclast formation in vitro was studied in metatarsal bones of embryonic mice of different ages cultured in the continuous presence of 3H‐thymi‐dine. In young bones (15 days), mainly proliferating, 3H‐thymidine‐incorporating progenitors gave rise to AcPP‐P cell and osteoclast formation. In older bones (16 and 17 days) osteoclasts were progressively more derived from postmitotic, unlabeled precursors. Irradiation of the metatarsal bones with a radiation dose of 5.0 Gy prior to culture resulted in a selective elimination of the proliferating progenitors, whereas the contribution of postmitotic precursors in AcPP‐P cell and osteoclast formation remained unchanged. The results demonstrate that in the periosteum of embryonic metatarsal bones a shift occurs from a population composed of proliferating osteoclast progenitors (15 days) to a population composed of postmitotic precursors (17 days) before multinucleated osteoclasts are formed (18 days). Obviously, postmitotic AcP‐negative precursors, already present in 16‐day‐old bones, differentiate into precursors characterized by tartrate‐resistant AcP activity, the preosteoclasts (17 days), which in their turn fuse into osteoclasts.
Development of the atrioventricular valve region in the human embryo
Authors: Magovern Jamie Hall , Moore G. William , Hutchins Grover M.
Published: February 2005

Severe cardiac malformations may involve the atrioventricular valve region, but the sequence of embryonic development of this important area has been little studied. In particular, the basis of atrioventricular muscular discontinuity, except at the conduction system, has remained unexplained. To examine this question, serial histologic sections of human embryos from the Carnegie Embryo‐logical Collection and from the Hopkins Pathology Collection were studied and six embryos were reconstructed. The atrioventricular sulcus can be identified in Carnegie stage 10 as an indentation or crease on the right side separating the heart tube from the umbilical vein. By stage 12 the sulcus has deepened and rotated anteriorly as the atria appear and the heart tube elongates rapidly within the confining pericardial space. Selective accumulation of cardiac jelly on the endocardial aspect of the constriction of the heart tube produced by the atrioventricular sulcus is pronounced by stage 14. By stage 16 the separation of the atrioventricular orifice into right and left components is well advanced, and by stage 18 the septation of the atria and ventricles is largely complete. The muscular connection between the atria and the ventricles becomes interrupted around most of the artioventricular sulcus, except for the His bundle, during the latter part of the embryonic period. The topography of the original sulcus assumes a catenoidal or saddle‐shaped configuration, i.e., convex in one plane and concave in the perpendicular plane. The tension and pressure relationships in such a structure would favor cardiac jelly accumulation and the eventual disintegration of lines of myocyte connections passing across the groove. The preservation of the His bundle connection is explained by the failure of the sulcus to completely encircle the heart.
A scanning electron microscopy and histological study on the effects of the mutant eyeless (e/e) gene upon the hypothalamus in the Mexican axolotl Ambystoma mexicanum Shaw
Authors: Eagleson Gerald W. , Malacinski George M.
Published: February 2005

A scanning electron microscopy, histological, and immunochemical investigation examined the effects of the mutant gene (e) upon hypothalamic development in the Mexican axolotl. The adult eyeless mutant is sterile. Previous studies indicated that this reproductive defect was due to the mutation's effect upon the hypothalamus.

The present study demonstrated the pleiotropic effects of the eyeless gene upon development of the hypothalamus. Scanning electron microscopy studies looked at the early ontogeny of the hypothalamohypophyseal system. The major morphological difference observed in the hypothalamus of normals compared to eyeless mutants was the reduced nature or complete lack of a preoptic recess in eyeless mutants. Early embryonic tissue movements also differed when normal siblings were compared to eyeless mutant axolotls. Histological examination looking for paraldehyde‐fuchsin‐positive secretory neurons revealed a paired nucleus preopticus in both normals and eyeless mutants, but this region lacked the emanating paraldehyde‐fuchsin‐positive fiber tracts in eyeless mutants. The neurohypophysis of the eyeless mutants was atrophied and contained far less paraldehyde‐fuchsin‐positive material when compared to normal axolotls.

Immunochemical studies were done to look at the distribution of immunoreactive luteinizing‐hormone‐releasing hormone (ir‐LHRH) in brains of eyed and eyeless mutant axolotls of different stages. This study detected deficiencies in ir‐LHRH in the anterior hypothalamus of eyeless mutants.

In general in the eyeless mutant axolotl, the observed anterior hypothalamic deficiencies are comparable to those observed in anurans which have had their optic vesicles removed. These observations suggest a possible utility of the eyeless mutant axolotl for studies concerned with endocrine development in the absence of hypothalamic modulation.
Calcium‐binding protein (28,000 Mr calbindin‐D28k) in kidneys of the bullfrog Rana catesbeiana during metamorphosis
Authors: Rhoten William B. , Gona Ophelia , Christakos Sylvia
Published: February 2005

A protein of approximately 28,000 relative molecular mass (Mr) cross‐reacting with antiserum against the 28,000‐Mr rat renal calcium‐binding protein (calbindin‐D28k) has been localized in the kidney of a salientian amphibian, Rana catesbeiana. Cells reactive for calbindin‐D28k were found in the distal tubule at all stages of metamorphosis by the unlabeled antibody peroxidase‐antiperoxidase technique. Adult kidneys appeared to have more calbindin‐D28k‐positive cells. The renal corpuscle, neck, and proximal tubule were negative. An immunoreactive 28,000‐Mr band that comigrated with the band of calbindin‐D28k was visualized by the immunoblot technique. The finding of the 28,000‐Mr calbindin‐D in the anamniotic kidney demonstrates that this calcium‐binding protein (CaBP) is phylogenetically older than our previous studies of higher vertebrates had revealed (Rhoten et al., 1985). Although the function of calbindin‐D28k in the distal nephron is unknown, this CaBP can now be presumed to have functional significance in the mesonephric as well as the metanephric kidney.
Morphology of ventral epidermis of Rana catesbeiana during metamorphosis
Authors: Robinson Douglas H. , Heintzelman Matthew B.
Published: February 2005

A detailed morphological examination of the bullfrog tadpole ventral epidermis and changes in structure that occur during metamorphosis has not been done. Knowledge of this is crucial to interpretation of physiological studies such as those dealing with development of transepithelial Na+ transport. Examination of tadpole epidermis with light microscopy reveals the presence of three different cell types: apical, basal, and skein. This epidermal morphology is constant until Taylor and Kollros (Anat. Rec. 94:7–23, 1946) stage 19 when degeneration of apical cells is noted. Stages 20 and 21 are characterized by rapid proliferation of basal cells and development of a true stratum germinativum together with the disappearance of other tadpole cell types. By stage 22, epidermal morphology is similar to that of the adult frog. Studies with the electron microscope reveal that as the proliferation proceeds during metamorphosis, the skein cells, at stage 20, differentiate to form the apical border of the skin. The development of the adult frog cell phenotype appears to mimic the cellular differentiation that occurs in the adult epidermis with the cells first developing into progranular cells in the intermediate stratum of the skin and then progressing to granular cells in the outermost living cell layer. The granular cells then undergo cornification to form the stratum corneum. Mitochondria rich cells are not seen in the developing epidermis until stage 21. These observations, when considered with previous results from Na+ transport studies (Hillyard et al.: Biochim. Biophys. Acta 692:455–461, 1982), suggest that both the physiological differentiation and morphological differentiation are simultaneous events.
Maturation of human fetal esophagus maintained in organ culture
Authors: Ménard Daniel , Arsenault Pierre
Published: February 2005

The purpose of this work was to study the human fetal esophagus maintained in organ culture. Esophageal explants from 8 fetuses aged from 12 to 16 weeks of gestation were cultured up to 21 days at 37°C in Leibovitz L‐15 serum‐free medium. Between 12 and 16 weeks of gestation, the esophagus has a stratified columnar ciliated epithelium, and glycogen aggregates are present in all cell layers. This morphology remains the same up to 5 days in culture. After 7 to 9 days, a vacuolization in the upper half layer occurs, leading to a lifting off of the ciliated layer and a flattening of the subjacent cells. After 15 days of culture, the esophageal epithelium is stratified squamous and the cells are exfoliated at the surface of the explants. Glycogen aggregates are still present in all layers. Islets of ciliated cells resting on the basal cell layers develop within the squamous epithelium. With the extension of the culture period up to 21 days, the general morphology of the epithelium does not change. The ultrastructural features of the newly formed squamous epithelium, with its basal lamina, are similar to that reported for human adult esophageal epithelium. During the course of the culture, the DNA synthesis continues as determined by autoradiography. It is concluded that it is possible to maintain viable human fetal esophagus in organ culture and that an accelerated maturation takes place leading to the formation of the adult esophageal epithelium.
Arterial supply to the pig intestine: An unusual pattern in the mesentery
Authors: Spalding Hugh , Heath Trevor
Published: February 2005

The arrangement of arteries in the mesentery in pigs was studied with latex casts and light microscopy. Arterial arcades, which are characteristic of the mesentery in man and other species, are absent. Instead, a narrow band of numerous, anastomosing arteries gives rise to up to about 500 bundles of arteries and accompanying veins, which radiate out in the mesentery. Each bundle contains up to 30 arteries, but these recombine as they approach the jejunum, and form 1–4 arteriae rectae.

The significance of the very large number of small arteries in the mesentery is not known, but they may play a role in the control of blood pressure in the intestinal wall, or as sites of countercurrent exchange.
The role of function in the development of human craniofacial form—A perspective
Authors: Kean M. R. , Houghton P.
Published: February 2005

As an anatomical region the head combines great diversity of function with close integration of structure. Consequently no structural component has autonomy of form. There is a sequence of maturation of functions and their related structural components, and in this sequence the nervous system and its supportive structures mature first. The nasal airway matures next in response to increasing body mass, and the masticatory system constitutes the last major functional system to reach maturity. The later the maturation of the function, the greater is the requirement for its related morphology to adapt to preceding skeletal templates. These matters of developmental sequence, and extrinsic as well as intrinsic craniofacial functions, are paramount considerations in interpreting the form of any component of head anatomy.
Immunolocalization of extracellular matrix proteins and collagen synthesis in first‐trimester human decidua
Authors: Kisalus Lydia L. , Herr John C. , Little Charles D.
Published: February 2005

The extracellular matrix (ECM) of first‐trimester human decidua was examined with indirect immunofluorescence using affinity‐purified antibodies to human collagen types I, III, IV, V, laminin, and fibronectin. In addition, the validity of the classification “mesenchymal‐epithelioid” for differentiated decidual cells was addressed using antibodies to the intermediate filament proteins, vimentin, a mesenchymal marker, and keratin, an epithelial marker. Biosynthesis of extracellular matrix components was examined by radiolabeling of decidual explants in culture with 3H‐proline, followed by immunoprecipitations of synthesized proteins with collagen type‐specific antibodies. Immunofluorescence showed decidual cells are embedded in an extensive network of collagen types I and III, and intracytoplasmic staining suggested synthesis of these collagens by the decidual cells. Collagen type IV and laminin localized in the external lamina which surrounds the differentiated decidual cell, and some fluorescence was evident in the peripheral cytoplasm. Immunoreactive collagen type V was observed in close association with the external lamina and in the peridecidual matrix. Fibronectin localized throughout the decidual ECM and in fibrillar and punctuate patterns in the decidual cell cytoplasm. Differentiated decidual cells retained a “mesenchymal” intermediate filament cytoskeleton containing an abundance of vimentin filaments, but very few, if any, keratin filaments. Collagen types I, III, V, and to a lesser extent, IV, were immunoprecipitated from the medium of decidual explants after 24 hours of culture, demonstrating in vitro synthesis and secretion of these collagens by first trimester human decidua.
Effect of optic nerve denervation on lens regeneration in adult newts, Triturus viridescens
Authors: Chan Frank , Orsbon Susan
Published: February 2005

This experiment was designed to study the effect of optic nerve denervation on lens regeneration. Adult newts, Triturus viridescens, were divided into 4 groups: A) lentectomized newts, which served as controls, B) lentectomized newts with the optic nerve exposed and lightly palpated, C) newts with lens removed and the optic nerve cut simultaneously, and D) newts with lens removed frist and optic nerve cut 7 days and 14 days later. Control animals required about 21 days to produce a new lens, and animals in group B demonstrated the same regeneration rate. In groups C and D, the regeneration rate was greatly retarded during the first 14 days. However, most of these animals regenerated a perfect new lens by 21 days postlentectomy.
Neurulation in the mouse I. The ontogenesis of neural segments and the determination of topographical regions in a central nervous system
Authors: Sakai Yoshio
Published: February 2005

Ontogenesis of neural segments and positional relationships between the segments and other organs during neurulation were studied in 1,423 ICR mouse embryos by binocular dissecting, light, and scanning electron microscopy.

Late in the presomite stage, two transverse sulci, preotic and otic, were seen on the prospective luminal surface of the neural folds. By somite stage 19, the former subdivided into five neuromeres, and by somite stage 21, the latter subdivided into four neuromeres. From the rostral, preotic sulcus, moreover, five other neuromeres were formed by somite stage 20, and between the otic sulcus and the first somite, two neuromeres were formed by somite stage 28. In the caudal part, from the level of the first somite, a total of 39 neuromeres were formed one after another by somite stage 39, and their positions almost correlated with each corresponding somite.

Furthermore, the isthmus grew in the boundary between the fifth and sixth neuromere. The most protruding zone in the preotic sulcus formed the eighth neuromere and was located adjacent to the first branchial arch and the trigeminal ganglion. The most protruding zone in the otic sulcus also formed the 11th neuromere and was located adjacent to the second branchial arch. The 12th and 13th neuromeres were situated adjacent to the otic vesicle; the 23rd to 28th neuromeres, adjacent to the forelimb bud; and the 40th to 46th neuromeres, adjacent to the hindlimb bud.
Morphological characterization of a granulocytosis/hypercalcemia‐inducing murine mammary carcinoma cell line
Authors: Riddle Clara V. , Lee Minako Y. , Lee Ming J.
Published: February 2005

A newly established cell line of a granulocytosis/hypercalcemiainducing murine mammary carcinoma (CE mammary carcinoma) grown in serum‐free culture medium secretes factors that stimulate proliferation of granulocytes and embryonal bone cells. These cultured cells retain the ability to produce granulocytosis and hypercalcemia when they are transplanted back into mice. In culture these cells form clusters of organized cells. Studies by scanning, transmission, and freeze‐fracture electron microscope techniques reveal that these in vitro tumor cells retain the structural epithelial characteristics of mammary epithelia. They maintain cellular polarity, microvilli, and complete tight junctions. Both the in vivo and in vitro tumor cells produce viral particles with the ultrastructural features of murine mammary tumor viruses. In both in vivo and in vitro conditions, A‐type particles are present intracellularly. B viral particles are present predominantly in the intercellular spaces. Since the structural characteristics of the cultured tumor cells are consistent with the features of mammary adenocarcinomas, this is a prime culture system for studying the tumor‐derived soluble factors.
Development of adipose tissues
Authors: Nnodim Joseph O.
Published: February 2005

Studies on the development of brown and white adipose: tissues and their relationship to ordinary connective tissue are the subject of the present review, which is updated to the fall of 1985. Primordial entities described as “primitive organs” have been noted at sites of adipose tissue development by numerous investigators. These “primitive organs” are clearly delineated from surrounding connective tissue and possess a well‐defined vascular network in the interstices of which cellular organization takes place.

The precursor cells of brown and white adipocytes appear to acquire their distinctive cytogenetic properties at a very early stage in the embryo. These progenitor cells temporarily exhibit structural similarities to fibroblasts and endothelial cells. This resemblance has led to speculation that fibroblasts and/or endothelial cells may be ancestral to adipocytes. However, recent in vivo and in vitro observations suggest that the brown adipose precursor cell is morphogenetically distinct from the white adipose precursor cell on one hand, and from fibroblasts and endothelial cells on the other.

In vitro studies have also shown that the pericytic elements present in both brown and white adipose tissue depots in the adult are quiescent precursor cells that may be recruited under certain circumstances. Areas for further inquiry by means of recently developed techniques are indicated.
A reexamination of the role of microfilaments in neurulation in the chick embryo
Authors: Schoenwolf Gary C. , Folsom David , Moe Ardis
Published: February 2005

Formation of wedge‐shaped neuroepithelial cells, owing to the constriction of apical bands of microfilaments, is widely believed to play a major part in bending of the neural plate. Although cell “wedging” occurs during neurulation, its exact role in bending is unknown. Likewise, although microfilament bands occupy the apices of neuroepithelial cells, whether these structures are required for cell wedging is unknown. Finally, although it is known that cytochalasins interfere with neurulation, it is unknown whether they block shaping or furrowing of the neural plate, or elevation, convergence, or fusion of the neural folds. The purpose of this study was to reexamine the role of microfilaments in neurulation in the chick embryo. Embryos were treated with cytochalasin D (CD) to depolymerize microfilaments and were analyzed 4–24 hr later. CD did not prevent neural plate shaping, median neural plate furrowing, wedging of median neuroepithelial cells, or neural fold elevation. However, dorsolateral neural plate furrowing, wedging of dorsolateral neuroepithelial cells, and convergence of the neural folds were blocked frequently by CD. In addition, neural folds always failed to fuse across the midline in embryos treated with CD, and neural crest cell migration was prevented. These data indicate that only the later aspects of neurulation may require microfilaments, and that certain neuroepithelial cells, particularly those that normally wedge with median furrowing and elevation of the neural folds, become (and remain) wedge‐shaped in the absence of apical microfilament bands. Thus, microfilament‐mediated constriction of neuroepithelial cell apices is not the major force for median neuroepithelial cell wedging and elevation of the chick neural plate. Further studies are needed to localize the motor(s) for these processes.
The anionic matrix at the rat glomerular endothelial surface
Authors: Avasthi Pratap S. , Koshy Valsala
Published: February 2005

The anionic macromolecules at the glomerular endothelial cell surface are visualized only when stained with cationic stains. We investigated the arrangement and composition of this anionic matrix at the luminal surface. Rat kidneys were perfused with anionic ferritin (pI 4.5), ferritin (pI 7.4), or cationized ferritin (CF, pI 8.3). Anionic ferritin (pI 4.5) did not bind to the capillary wall, ferritin (pI 7.4) bound discontinuously only to the laminae rarae of the basement membrane, but cationized ferritin (CF, pI 8.3) bound as a thick continuous layer to the cell plasmalemma and bound to the anionic matrix in the fenestral spaces. These observations show that an anionic matrix lines the entire capillary lumen surface, fills the fenestrae, and is interposed between the blood and the basement membrane at the fenestrae.

The anionic constituents at the capillary luminal surface were identified by in vivo digestion with specific enzymes. Absence of CF binding following digestion with specific enzymes was taken to indicate the presence of the particular glycoprotein known to be susceptible to the enzyme used. Neuraminidase digestion revealed that anionic sites over the surface plasmalemma are mainly from sialoproteins. In contrast, the matrix in fenestral channels contains heparan sulfate, hyaluronic acid, and sialoproteins. Papain digestion showed no glycolipids at the luminal surface. The functions of this continuous anionic layer located at the luminal surface of glomerular capillaries have not yet been established.
Ultracytochemical localization of adenylate cyclase in early human placenta
Authors: Spreca Antonio , Rambotti Maria Grazia , Ferrarese Remo , Pomili Giovanni , Angelini Antonio
Published: February 2005

A cytochemical study was carried out on adenylate cyclase (AC) activity in the early human placenta. Samples of placental villi were incubated in a medium containing adenylyl‐imidodiphosphate (AMP‐PNP) as specific substrate. No AC reaction product was encountered in placenta villi taken at 5 and 7 weeks of pregnancy. AC activity appeared at 9 weeks. At 9 and 10 weeks, AC reaction product was localized on the basal plasma membranes and on apposed plasma membranes of the Langhans cytotrophoblast. At 11 weeks AC activity was also clearly visible on Langhans cytotrophoblast and syncytiotrophoblast apposed plasma membranes. No AC reaction product was ever detected on the syncytiotrophoblast microvillar membrane. These results are in agreement with biochemical studies that localize AC on the villous trophoblast plasma membranes associated with the fetal circulation.
Morphometry of the human pulmonary acinus
Authors: Haefeli‐Bleuer Beatrice , Weibel Ewald R.
Published: February 2005

The geometry and morphometry of intraacinar airways in human lungs were studied on silicone rubber casts from two adult lungs. We defined acini as the complex of alveolated airways distal to the terminal bronchioles—that is, beginning with the first‐order respiratory or transitional bronchiole. The morphological properties of pulmonary acini are described. The acinar volume averages 187 mm3 (SD ± 79 mm3). Intraacinar airways branch dichotomously over about 9 generations (range 6–12). The internal airway diameter falls from 500 μm to 270 μm between acinar generations 0 and 10, whereas the outer diameter (including the sleeve of alveoli) remains constant at 700 μm. Towards the periphery the size of alveoli increases and clusters of alveoli become more numerous. The longitudinal path length of acinar airways (defined as the distance along the ducts from the transitional bronchiole to the alveolar sacs) averages 8.8 mm (± 1.4 mm). The morphometric data collected in this study are used to construct an idealized model of human acinar airways that can be related to existing models of the human bronchial tree.
Localization of inhibin in human testes by immunoperoxidase technique
Authors: Garde Seema V. , Moodbidri Shdhir B. , Phadke Achyut M. , Sheth Anil R.
Published: February 2005

Immunohistological studies on the localization of inhibin in human testes were carried out to investigate the cell types involved in inhibin synthesis/storage. The paraffin embedded testicular tissues were stained by an indirect immunoperoxidase technique. Specific antiserum to human testicular inhibin generated against the homogenous preparation of human testicular inhibin at our laboratory was used as the first antibody. Inhibin was found to be localized in Sertoli cells, spermatogonia, and primary spermatocytes. A weak positive reaction was also observed in spermatids. Interestingly, Leyding cells showed positive reaction indicating presence of inhibin in these cells too.
Trajectory architecture of the trabecular bone between the body and the neural arch in human vertebrae
Authors: Pal Gaya P. , Cosio Leo , Routal Rohini V.
Published: February 2005

The cancellous structure of vertebrae has been studied to investigate the direction of trabeculae and thus the lines of stress. The trabecular bone of the pedicle, connecting the body to the lamina, differed in different regions of the vertebral column. At C2 level, it was found that trabeculae are involved in transfer of the compressive forces from the superior articular surface to the inferior articular process and body. Throughout the thoracic region, trabeculae in the pedicle were inclined anteriorly towards the body, indicating that compressive forces in the thoracic spine are transferred from the neural arch to the body. In the lower lumbar region, trabeculae run from the body towards the neural arch. Trabeculae in the thoracic transverse proesses extend from the costal facet to the lamina, suggesting that weight brought by the ribs to the costotransverse articulations is transmitted to laminae through transverse processes.

A major part of the research was conducted while the first author (G.P.P.) was working as visiting Associate Professor at the Medical College of pennsylvania, Philadelphia, on a fellowship granted by the Educational Commission for Foreign Medical Graduates (E.C.F.M.G.).
Localization of cathepsin B in normal and hyperplastic human prostate by immunoperoxidase and protein A‐gold techniques
Authors: Sinha Akhouri A. , Gleason Donald F. , Limas Catherine , Reddy Pratap K. , Wick Mark R. , Hagen Kimberly A. , Wilson Michael J.
Published: February 2005

Cathepsin B, a lysosomal cysteine protease, was localized in normal prostate and benign prostatic hyperplasia (BPH) using immunoperoxidase and protein A‐gold techniques. Our objective was to determine whether cathepsin B was involved in the prostatic epithelium affected by nodular hyperplasia. All samples were collected immediately after prostatectomy. Immunohistochemical studies showed that the enzyme was expressed in the supranuclear cytoplasm of columnar cells and in numerous basal cells of normal and BPH acini. The strongest localization of cathepsin B occurred in acinar basal cells; hence, it is possible that cathepsin B could be useful as a marker for such cellular elements. Stromal macrophages showed reaction products, but lymphocytes and neutrophils did not. In both normal and hyperplastic glands, the enzyme was localized by gold particles in lysosomes, secretory granules, and vacuoles of columnar epithelial acinar cells. Immunoelectron microscopic study also showed the presence of cathepsin B in the heterochromatin (condensed chromatin) and nuclear membranes of columnar and basal cells, but not in euchromatin or nucleoli. At present, the function of cathepsin B in the nuclei of basal and columnar cells remains unknown. However, the cathepsin B in the cytoplasmic compartment might be associated with the lysosomal function of the cells. The role of cathepsin B as a marker for basal cell participation in the development of prostatic lesions should be studied further.
Kinetic analysis of thymocyte attachment to thymus stromal cells in culture by using phase‐contrast and scanning electron microscopy
Authors: Larochelle Gregory G. , Jones Kenneth H.
Published: February 2005

Direct cellular contact between thymocytes and thymus stromal cells within the thymus appears to contribute to the maturation of thymocytes. Thymocyte‐stromal cell complexes, formed in vivo, have been isolated by others and postulated to play a role in T‐cell differentiation. These previous studies have been hampered, however, by a time‐consuming isolation procedure from which only small numbers of these complexes are recovered. We have examined a model to study thymocyte‐stromal cell complexes in vitro in which thymocytes are added to primary cultures of thymus stromal cells. In the present study, we found that thymocytes were histotypically selective in their attachment to thymus stromal cells. We also investigated the kinetics of thymocyte attachment to these thymus stromal cells. Cultures were examined at selected time intervals from 5 min through 3 days of incubation. Thymocyte attachment to stromal cells was a biphasic interaction, with maximum surface attachment at 15 min of cocultivation, followed by migration of thymocytes into the cultures. Morphological studies were confirmed by using3H‐leucine‐labeled thymocytes and liquid scintigraphy. With increased time in culture, thymocytes became amoeboid and migrated between the layers of stromal cells where thymocyte mitotic figures were seen at 4 and 8 hr. In some cases it appeared that stromal cells, which often grew two to three cell layers deep, played an active role in enclosing thymocytes within the cultures. Large numbers of viable thymocytes were observed in the cultures at 24 hr. The number of thymocytes then decreased progressively on days 2 and 3, when relatively few were found within the layers of the culture.
Regional distribution of fiber types in developing baboon diaphragm muscles
Authors: Maxwell Leo C. , Kuehl Thomas J. , McCarter Roger J. M. , Robotham James L.
Published: February 2005

Fiber type distribution and mean fiber area were determined for seven sites in diaphragm muscles of premature (140 days gestation), full‐term (180 days gestation), and adult baboons. Within a group, data did not differ significantly amongst the seven sites. The diaphragm of premature animals had a large proportion [56(±2)%] of type IIc fibers, smaller proportions of type I, IIo, and IIh fibers [16(±2), 21(±1), and 7(±2)%, respectively], and no type IIg fibers. Full‐term animals had fewer type IIc [2(±1)%] fibers, greater proportions of type I [46(±2)%], IIh [23(±1)%], and IIg [11(±1)%] fibers, and a similar proportion of type IIo fibers [17(±1)%]. Diaphragm from adult baboons had similar proportions of type I, IIo, IIh, IIg, and IIc fibers in females [39(±4), 20(±2), 1(±1), 41(±5), and 1(±1)%] and males [48(±2), 16(±1), 0(±0), 36(±2), and 3(±2)%]. Fiber area for premature [143(±9), 210(±15), 231(±15), and 156(±16) μm2 for type I, IIo, IIh, and IIc fibers], newborn [317(±32), 374(±36), 468(±42), 498(±43), and 322(±37) μm2 for type I, IIo, IIh, IIg, and IIc fibers], and for type I, IIo, IIg, and IIc fibers from adult female [1,759(±130), 2,365(±284), 5,026(±742), and 1,843(±111) μm2] and adult male [2,513(±221), 3,987(±267), 6,102(±376), and 2,833(±151) μm2] baboons indicated growth which correlated with body weight. Our results also show that metabolic and contractile enzymes develop normally, but growth of respiratory muscle fibers is arrested, during 10 days following premature birth.
High resolution electron microscopy of nonstoichiometric apatite crystals
Authors: Nelson D. G. A. , Barry J. C.
Published: February 2005

The application of high resolution electron microscopy, computer image processing, and image simulation techniques to the investigation of synthetic nonstoichiometric apatites has provided new details of apatite crystal growth mechanisms. Under certain precipitation conditions, calcium‐deficient apatites with distinct octacalcium phosphate (OCP)‐apatite intergrowths have been observed. Apatite crystals with unit‐cell thick overgrowths of OCP on their surfaces confirmed the stepwise hydrolysis crystal growth mechanism initially proposed by Brown (Nature 196:1048–1050). However, many crystals also contained a central two‐dimensional OCP inclusion one to two unit cells thick, embedded in an apatite matrix. Similar planar defects have been observed in dental enamel, dentin, and bone apatite crystals. We have developed a modified version of Brown's stepwise OCP hydrolysis apatite crystal growth mechanism to explain the formation of crystals with OCP central planar defects. The mechanism involves the nucleation of an OCP seed that grows until it reaches a critical size, rh, before OCP hydrolysis occurs. Apatite subsequently grows epitaxially on the OCP seed, thereby embedding it in the center of an apatite crystal. Apatite growth is facilitated by partial screw dislocations emanating from the planar defect.
Insect hemolymph factor promotes muscle histolysis in solenopsis
Authors: Davis Walter L. , Jones Ruth Gwendolyn , Farmer Gene R.
Published: February 2005

Hemolymph was collected from both normal (virgin) females (control hemolymph) and artificially inseminated females (experimental hemolymph) of Solenopsis, ssp., the imported fire ant (primarily S. invicta and S. geminata). When the control hemolymph was injected into normal females, breakdown of the thoracic flight musculature was not seen 24 hr postinjection. In contrast, when the experimental hemolymph was injected into normal females, flight muscle histolysis was marked 24 hr postinjection. When the experimental hemolymph was heated to 70°C prior to injection into normal females, subsequent flight muscle breakdown was not not seen. The injection of freshly collected semen into normal females produced no effect on flight muscle structure. Also, the injection of the experimental hemolymph into normal, alate males produced no muscle histolysis. These observations suggest that the hemolymph from inseminated females contains a factor (or factors) that induces the specific breakdown and subsequent dissolution of the complex thoracic flight musculature. Other thoracic muscles (leg muscles, intersegmental muscles, etc.) are not affected. Based on observations made in both insect muscles as well as vertebrate skeletal muscles, it is suggested that such a hemolymph factor may act by disrupting the structural integity of muscle cell membranes, resulting in significant changes in membrane permeability, especially with regard to calcium ions.