bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomy of the cruciate ligaments and their function in extension and flexion of the human knee joint
Authors: Fuss Franz K.
Published: February 2005

The areas of the femoral origin of the cruciate ligaments have approximately the shape of sectors of ellipses, the one for the anterior ligament on the lateral condyle posteroproximally and the one for the posterior ligament on the medial condyle distally. By means of a new technique of dissection, combined with the use of X‐rays, the change in distance between the origin and insertion and so the change of tension of single bundles of the ligaments could be analyzed. Only a rather thin bundle in each cruciate ligament is in constant tension: “guiding bundles.” The maximal diminution of distance between the origin and insertion for some bundles is 65%. In the anterior cruciate ligament the majority of fibers are taut in extreme extension: “limiting bundles.” The same is true in the posterior cruciate ligament in extreme flexion. There are also some fibers, especially in the posterior cruciate ligament, that are taut only in an intermediate position. The geometric analysis of the function of different groups of fibers was performed by a modification of Menschik's concept of a four‐bar link.
Immunohistochemical and ultrastructural study of human melanoma colonies grown in soft agar
Authors: Persky Bruce , Meyskens Frank L. , Hendrix Mary J. C.
Published: February 2005

An immunohistochemical and ultrastructural study of human melanoma colonies grown in soft agar for up to 50 days was performed. Three morphological variants of developing tumor colonies are reported: (1) large light colonies, (2) small dark colonies, and (3) smooth‐edged colonies. The large light colony variant is the most frequently observed in the soft agar assay (≈︁70%), followed by the dark colony variant (≈︁27%), and the smooth‐edged colony variant (≈︁3%). Major morphological characteristics are associated with each variant, as shown with light microscopy (LM) and transmission electron microscopy (TEM). Both LM and TEM analyses demonstrated that the large light colony variant was hypomelanotic and contained a microfibrillar extracellular matrix (ECM). The small dark colony variant was found to be hypermelanotic and contained a less demonstrable ECM. The smooth‐edged variant has an encapsulated periphery, no demonstrable ECM, and tightly packed cells with desmosome‐like junctions. In order to characterize further the ECM in the most commonly observed variant, the large light colony, specific antibodies to fibronectin (FN) and collagen types IV and V (COLs IV and V) were applied and observed with immunofluorescence microscopy and immu‐noperoxidase. In paraffin sections of melanoma colonies, FN was observed associated with both the cell surface and the ECM. However, no specific staining was seen for COLs IV and V. In addition, ruthenium red was used to preserve and selectively bind to glycosaminoglycans (GAGs) and proteoglycans (PGs). TEM studies reveal GAG‐like granules stained with ruthenium red in the fibrillar ECM and a dotted, punctate staining of the cell surface. Understanding the biological and architectural composition of developing melanoma tumor colonies in soft agar could contribute to the development of more efficient chemo‐therapeutic strategies.
Quantitative morphology of the central fovea in the primate retina
Authors: Krebs Wolf , Krebs Ingeborg P.
Published: February 2005

Electron micrograph composites of tangential sections of the fovea centralis of three cynomolgus monkeys (Macaco, irus) and one baboon (Papio anubis) were used to determine the spatial density of the principal retinal cells. In the center of the foveola, the density of cones ranged from 113,000 to 230,000/mm2, and pigment epithelial cells from 4,900 to 7,000/mm2. At a distance of 500μm from the foveolar center the density of the cone cell pedicles ranged from 29,000 to 36,300/mm2, and the density of horizontal cells ranged from 19,000 to 25,100/mm2. Densities of bipolar, Muller, and amacrine cells were determined in only two monkeys and in the baboon.

The fact that the cone cell pedicles have a larger diameter than the foveolar cones explains the geometry of the fovea. The morphology of the junction between foveolar cone outer segments and the pigment epithelium reflects the complex metabolism of this functional unit. The comparison with the peripheral primate retina suggests that the densities of horizontal and bipolar cells, but not of amacrine and Muller cells, are correlated with the density of cone cell pedicles.
Epithelial cytodifferentiation and extracellular matrix formation in enamel‐free areas of the occlusal cusp during development of mouse molars: Light and electron microscopic studies
Authors: Sakakura Yasunori , Fujiwara Naoki , Nawa Tokio
Published: February 2005

Mandibular first molars in mice ranging in age from 18 days prenatal to 5 days postnatal were used for light and electron microscopic examinations of the enamel‐free area (EFA) during development of the occlusal cusp (mesiobuccal cusp). Notable morphological changes in the inner enamel epithelium and the cells of the stratum intermedium were observed. At prenatal age of 18 days, the inner enamel epithelium of the EFA (EFA epithelium) was composed of a layer of columnar cells and covered by the cells of the stratum intermedium. Two days after birth, the EFA epithelium was made up largely of preameloblasts, with mitochondria located in the proximal side of the cells toward the stratum intermedium. The cells of the stratum intermedium were irregularly shaped, with wide intercellular spaces between them. At a postnatal age of 3 days, most of the EFA epithelial cells resembled maturation‐stage ameloblasts, being short and columnar in shape and having nuclei located in their proximal side. Distal cell membranes were folded, and mitochondria were scattered throughout the cytoplasm. In 4‐day‐old mice, the EFA epithelium was found to be formed of short columnar or cuboidal cells with distinct intercellular spaces. The cells of the stratum intermedium could no longer be detected, and cells of the EFA epithelium could not be distinguished from those of the stellate reticulum. Odontoblasts of the EFA were arranged and polarized parallel to the basal lamina, and odontoblastic processes extended toward the cusp tip. The orientation of thin and thick collagen fibers within predentin and dentin was also parallel to the basal lamina. Even after dentin mineraliza tion, disrupted basal lamina and long, aperiodic, fine fibrils were found between the epithelium and the dentin. Following the disappearance of the basal lamina and fine fibrils, stippled material and crystals appeared on the dentin surface. The mineralized matrix, which x‐ray microanalytical energy peaks identified as containing calcium and phosphorus, was continuous with enamel in the distal slope of the cusp at the cusp tip. Thus, the inner enamel epithelium of the EFA differentiated into secretory cells capable of enamel‐like matrix formation. In conclusion, development of EFA in mouse molars seems to be a system suitable for use in studying both the involvement of extracellular matrix, including basal lamina constituents, in ameioblast differentiation, and the role of the cells of the stratum intermedium, together with the ameloblasts, in comprising a single functional unit responsible for enamel formation.
Light and electron microscopy studies of the ulnar, saphenous, and caudal cutaneous sural nerves of the dog
Authors: Illanes O. , Henry Julie , Skerritt G.
Published: February 2005

Transverse sections of the ulnar, saphenous, and sural nerves taken at specific levels in normal, young‐adult beagle dogs were examined qualitatively and quantitatively at both the light and electron microscopic levels. The aim of this investigation was to provide baseline information for future studies of peripheral nervedisease in this species. A systematic sampling technique was used for the determination of nerve components (i.e., unmyelinated axons and Schwann cell and fibroblast nuclei). In all nerves sampled, the average size distribution for unmyelinated axons was unimodal, and most of the axons were 0.4–1.1 μm in diameter. Within this range, there were slight individual and nerve‐to‐nerve variations in the location of the largest diameter peak. The mean densities of Schwann cell nuclei (numbers/mm2) ranged from 841/mm2 in the palmar branch of the ulnar nerve, to 1,223/mm2 in the caudal cutaneous sural nerve, being nearly four times the average density or fibroblast nuclei.

In every animal and in almost every nerve, a few abnormalities were found; and these should be kept in mind when assessing peripheral nerves in the dog.
Variations in atrioventricular valve innervation in four species of mammals
Authors: Williams Terence H. , Folan Jean C. , Jew Jean Y. , Wang Yan‐Feng
Published: February 2005

In this series of studies, the innervation patterns of whole‐mount preparation of bicuspid and tricuspid valves were studied by light microscopy in the mouse, rat, guinea pig, and opossum. The acetylcholinesterase‐positive networks of nerve fibers showed many similarities in the basic patterns of valve innervation in all of the species studied, but several interspecies variations were observed. The basal zone of the valve adjacent to the fibromuscular atrioventricular ring displayed the most dense plexus of nerves, with acetylcholinesterase‐positive fibers being seen across the width of the valve. In the intermediate zone of the valve, less dense plexuses of nerve fibers were found; and these were more numerous in the cuspal areas and less numerous in the intervening commissural areas. In the distal portions of the valve, nerve networks arborized extensively, with some of their nerve fibers extending toward the chordae tendineae and the free edges of the valve cusps. Only in the guinea pig and opossum did these fibers reach the free margin of the valve cusp, where they either ended directly as free nerve endings or lay parallel to the free edge of the cusp, often running between adjacent chordae tendineae. Although the patterns of innervation were similar in both bicuspid and tricuspid valves, the innervation density of the bicuspid valve was greater than that of the tricuspid valve for each species examined.

A distinguishing feature of guinea pig and opossum tricuspid valves was that their chordae tendineae were relatively more prominent and more densely innervated than the bicuspid chordae tendineae. Free nerve endings with no light microscopic evidence of specialization were present throughout the bicuspid and tricuspid valves of all species studied. Some nerve endings in the opossum showed evidence of specialization, with brush‐like arborizations leading to presumed free terminals seen chiefly in the distal zone of the valve cusps. Although some general tendencies were apparent, we have demonstrated that interspecies heterogeneity exists in the terminal networks of the atrioventricular valves of mouse, rat, guinea pig, and opposum.

In spite of the questions raised regarding the significance of valve innervation in light of the success of valve prostheses, there is relatively high morbidity and mortality associated with heart valve replacement, partly due to deterioration in ventricular function. We and other investigators have reported that valvar nerves extend to the chordae and papillary muscles, varying with valve and species.

This anatomical information about normal valves helps to lay the foundation for future studies of the role of valve innervation in the regulation of cardiac function and dysfunction. Such knowledge should be applicable for the control and management of myocardial infarction, valve disease, valve replacement, valvuloplasty, cardiac transplantation, administration of drugs, etc.
Distribution of type IV collagen, laminin, and fibronectin during maxillary process formation in the chick embryo
Authors: Xu Zenglu , Parker Susan B. , Minkoff Robert
Published: February 2005

The presence and distribution of laminin, type IV collagen, and fibronectin were analyzed in the facial primordia and developing primary palates of chick embryos from stages of development corresponding to maxillary process formation and primary palate closure. Frozen sections through the maxillary process and roof of the stomodeum were prepared for indirect immunofluorescence employing a biotin‐avidin system using monoclonal antibodies against laminin, type IV collagen, and fibronectin. Light microscopic examination of sections stained with antibodies against type IV collagen revealed a much stronger fluorescent signal in the roof of the stomodeum than in the maxillary process at all stages examined. Regional differences in signal intensity and staining patterns were noted within the maxillary process; for example, the lateral surface of the maxillary process displayed a much less intense signal at most stages examined than the inferior and medial surfaces. The signal from sections of the maxillary process stained with laminin was much stronger than the signal from the same tissues stained with collagen. Regional differences in signal intensity within the maxillary process were minimal in sections stained with antibodies to laminin, in contrast to the differences seen in sections stained with antibodies to type IV collagen. Differences in signal intensity between the maxillary process and the roof of the stomodeum with laminin were slight. Sections stained with antibody to fibronectin displayed intense staining throughout the mesenchyme in both the maxillary process and the roof of the stomodeum.

From comparison of the data of type IV collagen and laminin, the following hypothesis is proposed. In structures which undergo rapid change in form, such as the facial primordia, collagen distribution and/or organization is altered to a much greater extent than laminin, which is more uniformly distributed and which may be required for structural support of other developmentally regulated macromolecules. Where tissue morphology must be maintained, such as the roof of the stomodeum, the concentration and organization of type IV collagen is maintained in a manner that confers stability to these regions.
The role of the mesenchyme in mouse neural fold elevation. I. Patterns of mesenchymal cell distribution and proliferation in embryos developing in vitro
Authors: Morris‐Wiman Joyce , Brinkley Linda L.
Published: February 2005

Using the computer‐assisted method of smoothed spatial averaging, spatial and temporal patterns of cell distribution and mitotic activity were analyzed in the cranial mesenchyme underlying the mesencephalic neural folds of mouse embryos maintained in roller tube culture. Total cell density increased in central and medial mesenchymal regions after 12 hr in culture, decreased after 18 hr, and showed a further decrease after 2 hr when the neural folds of the embryos had elevated, converged, and were fusing or fused. Mitotic activity, as measured by the ratio of 3H‐thymidine‐labeled cells to unlabeled cells, was highest in the central mesenchyme at all culture times.

Embryos were also cultured in the presence of diazo‐oxo‐norleucine (DON), which inhibits glycosaminoglycan and glycoprotein synthesis. After 24 hr in culture, neural folds of DON‐treated embryos had failed to elevate. Total cell density increased in central and medial regions of the mesenchyme of DON‐treated folds at 12 hr but showed no significant decrease in these regions with further culture. Mitotic activity was highest in the central mesenchyme of these treated embryos.

These results suggest that cell distribution patterns observed in the cranial mesenchyme during neural fold elevation in normal cultured embryos are not produced by regional differences in mitotic activity. Rather, we propose that cell distribution patterns in the central and medial regions of the mesenchyme result from expansion of a glycosaminoglycan‐rich extracellular matrix that disperses cells from these regions and decreases their density. In DON‐treated embryos, in which expansion of the mesenchyme is prohibited by the decreased glycosaminoglycan and glycoprotein content of the extracellular matrix, mitotic activity apparently determines these patterns.
Neuropeptide Y localization in telencephalic and diencephalic structures of the ground squirrel brain
Authors: Reuss Stefan , Hurlbut Edward C. , Speh Joan C. , Moore Robert Y.
Published: February 2005

The distribution of neuropeptide Y‐immunoreactive (NPY‐IR) perikarya, fibers, and terminals was investigated in the brain of two species of hibernatory ground squirrels, Spermophilus tridecemlineatus and S. Richardsonii, by means of immunohistochemistry. In the telencephalic and diencephalic structures studied, distinct patterns of NPY‐IR were observed which were essentially identical in male and female animals of both species. No differences in amount or distribution of NPY‐IR structures were observed between animals which had been in induced hibernation for several months before sacrifice in March/April and those sacrificed one week after their capture in May. In some brain structures (e.g., the hypothalamic arcuate nucleus), IR cell bodies were observed only after pretreatment with colchicine.

NPY‐IR perikarya and fibers were found in the cerebral cortex, caudate nucleus‐putamen, and dorsal part of the lateral septal nucleus. Dense fiber plexuses were seen in the lateral and medial parts of the bed nucleus of the stria terminalis. The numbers of IR perikarya observed in the medial part of the nucleus increased following intraventricular colchicine injections. The accumbens nucleus exhibited few IR cells and many fibers. Claustrum and endopiriform nuclei showed a considerable number of stained cells and fibers that increased in number and staining intensity in colchicine‐treated ground squirrels. The induseum griseum showed a small band of IR cell bodies and varicose fibers. Bipolar of multipolar IR cells and varicose fibers were found in the basal nucleus of the amygdala.

Dense fiber plexuses as well as IR terminals were seen in the median, medial, and lateral preoptic areas of the hypothalamus. Terminals and relatively few fibers were located in the periventricular, paraventricular, and supraoptic nuclei. The anterior, lateral, dorsomedial, and ventromedial hypothalamic nuclei contained relatively large numbers of terminals and fibers. In the suprachiasmatic nuclei, dense terminals were distributed mainly in the ventromedial subdivision. In the median eminence, immunoreactive terminals were concentrated in the external layer, with fibers predominant in the internal layer. NPY‐IR perikarya were observed only in the arcuate nucleus of the hypothalamus and only following colchicine treatment. In the epithalamus (superficial part of the pineal gland and habenular nuclei), varicose fibers appeared mainly in perivascular locations (pineal) or as a dense plexus (habenular nuclei). These results from ground squirrels are discussed in comparison to those obtained in other species and with regard to considerations of the physiological role of NPY.
Occurrence of colloid‐containing follicles and ciliated cysts in the hypophysial pars tuberalis from guinea pigs of various ages
Authors: Kameda Yoko
Published: February 2005

Colloid‐containing follicles and ciliated cysts in the hypophysial pars tuberalis of guinea pigs at various ages ranging from 5 days to 36 months were examined by periodic acid‐Schiff (PAS) reaction, immunohistochemistry, and electron microscopy. The follicles storning PAS‐positive colloid were encountered in the pars tuberalis of all guinea pigs examined, although only a few were present in young animals. The follicles gradually increased in number with age. The largest number of follicles was found in the senile male group: 141.3 ± 11.9, about 10 times the number in the 5‐day‐old male group. The follicles were scattered throughout the entire length of the pars tuberalis. Follicles with enlarged luminal cavities were concentrated in the ventral caudal region surrounding the infundibular stem and merges with the pars distalis. Three different types of follicles were found by electron microscopy:(1) those surrounded by nongranulated follicular cells that may correspond to the stellate‐follicular cells in the pars distalis, (2) those surrounded by specific cells that were packed with vesicular inclusions, and (3) those surrounded by granulated cells that may be gonadotropes. In the follicles lined by nongranulated follicular cells, long, prominent microvilli and cytoplasmic processes protruding into the lumen and invaginations of colloid were often observed at the apical cell region. The follicles lined by the specific cells having numerous vesicles were localized only in the ventral caudal portion. The vesicles ranged from 200 to 700 nm in diameter, and the outer surface of their limiting membrane was partly studded with ribosomes. Gonadotropes immunoreactive to the luteinizing hormone (LH) and follicle‐stimulating hormone (FSH) antisera were distributed in the guinea pig pars tuberalis. As well as the typical follicles described above, the follicles composed solely of granulated cells showed microvilli protruding into the cavities and junctional complexes at the apical lateral surface. They stored heterogeneous materials in the lumina. Some secretory granules gave the appearance of being discharged into the lumen. Ciliated cysts were frequently observed in the pars tuberalis; their incidence was 71.7%. The ciliated cysts were much larger than colloid‐containing follicles. Cystic cavities were only partly filled with heterogeneous materials showing colloid‐like, flocculent, and granular features.
Localization of pigment cells in cultured frog skin
Authors: Denefle Jean‐Pierre , Lechaire Jean‐Pierre
Published: February 2005

The pigmentation pattern of ventral skin of the frog Rana esculenta consists mainly of melanophores and iridophores, rather than the three pigment cells (xanthophores, iridophores, and melanophores) which form typical dermal chromatophore units in dorsal skin. The present study deals with the precise localization and identification of the types of pigment cells in relation to their position in the dermal tracts of uncultured or cultured frog skins. Iridophores were observed by dark‐field microscopy; both melanophores and iridophores were observed by transmission electron microscopy.

In uncultured skins, three levels were distinguished in the dermal tracts connecting the subcutaneous tissue to the upper dermis. Melanophores and iridophores were localized in the upper openings of the tracts directed towards the superficial dermis (level 1). The tracts themselves formed level 2 and contained melanophores and a few iridophores. The inner openings of the tracts made up level 3 in which mainly iridophores were present. These latter openings faced the subcutaneous tissue.

In cultured skins, such pigment‐cell distribution remained unchanged, except at level 2 of the tracts, where pigment cells were statistically more numerous; among these, mosaic pigment cells were sometimes observed.
Immunocytochemical localization of growth hormone and growth hormone‐releasing hormone immunoreactivity in the brain and pituitary of the little brown bat
Authors: Anthony Edythe L. P. , Bruhn Thomas O. , Weston Paula J.
Published: February 2005

Anterior pituitary cells exhibiting growth hormone (GH) immunoreactivity and forebrain neurons containing growth hormonereleasing hormone (GHRH) immunoreactivity were identified in little brown bats (Myotis lucifugus) using light microscopic immunocytochemistry. Pituitary somatotropes appeared as ovoid or polyhedral cells that were distributed throughout most of the pars distalis, with the exception of its most rostral region where this cell type was scarce. GH‐immunoreactive cells occupied approximately one‐third of the total volume of the pars distalis; this proportion did not differ significantly between males and females or in bats collected at different times of year. Neuronal perikarya containing immunoreactive GHRH were observed in the hypothalamic arcuate and suprachiasmatic nuclei, as well as in the cortical and subcortical telencephalon. Fibers were most evident in the median eminence, paraventricular and periventricular nuclei, and molecular layer of the cerebral cortex. Fine fibers were also accumulated in the bed nucleus of the stria terminalis and in the amygdala.
Changes in cells' secretory organelles and extracellular matrix during endochondral ossification in the mandibular condyle of the growing rat
Authors: Marchi Fausto , Luder Hans U. , Leblond Charles‐Philippe
Published: February 2005

The mandibular condyle from 20‐day‐old rats was examined in the electron microscope with particular attention to intracellular secretory granules and extracellular matrix. Moreover, type II collagen was localized by an immunoperoxidase method.

The condyle has been divided into five layers: (1) the most superficial, articular layer, (2) polymorphic cell layer, (3) flattened cell layer, (4) upper hypertrophic, and (5) lower hypertrophic cell layers. In the articular layer, the cells seldom divide, but in the polymorphic layer and upper part of the flattened cell layer, mitosis gives rise to new cells. In these layers, cells produce two types of secretory granules, usually in distinct stacks of the Golgi apparatus: type a, cylindrical granules, in which 300‐nm‐long threads are packed in bundles which appear “lucent” after formaldehyde fixation; and type b, spherical granules loaded with short, dotted filaments. The matrix is composed of thick banded “lucent” fibrils in a loose feltwork of short, dotted filaments.

The cells arising from mitosis undergo endochondral differentiation, which begins in the lower part of the flattened cell layer and is completed in the upper hypertrophic cell layer; it is followed by gradual cell degeneration in the lower hypertrophic cell layer. The cells produce two main types of secretory granules: type b as above; and type c, ovoid granules containing 300‐nm‐long threads associated with short, dotted filaments. A possibly different secretory granule, type d, dense and cigar‐shaped, is also produced. The matrix is composed of thin banded fibrils in a dense feltwork.

In the matrix of the superficial layers, the “lucency” of the fibrils indicated that they were composed of collagen I, whereas the “lucency” of the cylindrical secretory granules suggested that they transported collagen I precursors to the matrix. Moreover, the use of ruthenium red indicated that the feltwork was composed of proteoglycan; the dotted filaments packed in spherical granules were similar to, and presumably the source of, the matrix feltwork. The superficial layers did not contain collagen II and were collectively referred to as perichondrium. In the deep layers, the ovoid secretory granules displayed collagen II antigenicity and were likely to transport precursors of this collagen to the matrix, where it appeared in the thin banded fibrils. That these granules also carried proteoglycan to the matrix was suggested by their content of short dotted filaments. Thus the deep layers contained collagen II and proteoglycan as in cartilage; they were collectively referred to as the hyaline cartilage region.
Light and electron microscopic observations on ciliated vacuoles and cysts in the oviductal and endocervical epithelia of the rabbit
Authors: Odor D. Louise
Published: February 2005

Ciliated vacuoles and intraepithelial cysts have been observed in oviductal and endocervical epithelia of rabbits. In this study, rabbits under various hormonal conditions were studied by light and transmission electron microscopy and tissue culture in an attempt to determine their distribution and origin. Ciliated vacuoles most frequently lay in the basal cytoplasm, below or beside the nucleus, and very close to the basal lamina. A few were apically located. Their average diameter was 8.8 by 5.1 μm. Cilia and microvilli projected into the vacuolar lumen. These vacuoles were located intracellularly as evidenced first by the degeneration of both their cilia and microvilli and the moderately dense matrix that often filled the vacuolar lumen, as observed by electron microscopy. Secondly, phase microscopy of the living endocervical epithelium allowed us to observe the beating of the cilia within the vacuoles, not on the surface of such cells. Thirdly, ruthenium red stained the surface glycocalyx of the ciliated and secretory cells, but not that of the cilia and microvilli within the vacuoles.

The intraepithelial cysts were not observed in all tissue blocks. The largest numbers were found in ovariectomized animals treated for 3 and 5 days with estradiol. More were seen in the isthmus and cervix than in the fimbria and ampulla. The cysts were located most often within the epithelium along the sides of, and at the bases of, the mucosal folds. They were lined by flattened epithelium of various combinations of secretory and ciliated cells.

An unusual cell type was associated with some of the cysts and ciliated vacuoles. Its cytoplasm contained aggregates of mitochondria and vesicles whose contents varied in density. Although the genesis of the ciliated vacuoles is not certain, our results indicate that they may arise from aberrant positioning of proliferating procentrioles or from a defect in targeting or transporting the centrioles to the apical plasma membrane to serve as basal bodies. Fusion of adjacent ciliated vacuoles with lumina lined by secretory cells having deep apical invaginations appeared to contribute to the formation of cysts.
Morphological innervation pattern of the developing rabbit heart
Authors: Roberts L. A.
Published: February 2005

The morphological innervation pattern of developing fetal and neonatal rabbit hearts was delineated histochemically by a cholinesterase/silver procedure and immunohistochemically with the monoclonal antibody HNK1, an antibody which recognizes some cells derived from neuroectoderm. Cholinesterase‐containing nerves appeared distally on the outflow tract by gestational day 15 (G15). Isolated cells with cholinesterase‐stained fine processes were present near the base of the pulmonary trunk. HNK1 antibody stained the same nerves and ganglia revealed by the cholinesterase reaction and other nerves in the rabbit heart. It was used to confirm that cells with fine neuron‐like processes were present before nerve ingrowth. The G14 heart contained many HNK1 staining cells in the right atrium, outflow, and inflow tracts; cells with fine processes were few but increased at G16. By G17, a plexus of interweaving nerves and associated cells began to form at the base of the pulmonary trunk. Fine nerves encircled the base of the aorta, and others crossed the intercaval region dorsally. At G19, nerves (1) extended downward from a rich “bulbar” plexus along the front ventricular surface, (2) grew near the epicardial surface at the base of the heart along the atrial floor and ventricular roof, (3) traversed the vena cavae and intercaval region to enter the atrial roof, and (4) crossed the coronary sinus to reach the back ventricular walls. By G23, cholinesterase‐staining nerves and ganglia in the atria and, epicardially, in the ventricles formed the general innervation pattern of the newborn and adult rabbit heart.
Fiber type composition of the human female trapezius muscle: Enzyme‐histochemical characteristics
Authors: Lindman R. , Eriksson A. , Thornell L.‐E.
Published: February 2005

The anatomy of the human trapezius muscle is complex, with an extensive origin and fibers running in different directions. The muscle is commonly divided into three different muscle portions according to the fiber direction: the descending, transverse, and ascending portions. In a previous study in males, the structure of the muscle differed between different portions with respect to the enzyme‐histochemical fibertype profile. The lower regions of the descending portion and the transverse and the ascending portions had a predominance of type I fibers. The type II fibers were more frequent in the upper regions of the descending portion, and the cross‐sectional fiber area in this region of the muscle was smaller. In this study, we have investigated the trapezius muscle in females and compared the results with those from males. The different portions of the female muscle had a relatively even fiber‐type composition. However, there tended to be fewer type I fibers and more type IIB fibers in the descending portion of the muscle, and the fibers of the lower regions of the descending portion were somewhat larger. The fiber‐type distribution pattern was similar to that of the male trapezius muscle, but the mean cross‐sectional area of the fibers in the female muscle was considerably smaller. Thus, our conclusion is that the trapezius muscle of females has a similar activity pattern as that of males. The significantly smaller cross‐sectional fiber area, however, may indicate a lower functional capacity which may be of importance in the development of neck and shoulder dysfunction in females.
Diffusion or autocatalysis of retinoic acid cannot explain pattern formation in the chick wing bud
Authors: Papageorgiou S. , Almirantis Y.
Published: February 2005

We have collected several experimental data of pattern duplications due to the ZPA transplantation or application of retinoic acid on the developing chick limb bud. We have compared these data with the predictions of models based on diffusion or autocatalysis of retinoids. It turns out that these models cannot comprehensively explain the data. More specifically, retinoic acid cannot be either diffusing from a ZPA source or participate in an autocatalytic gradient formation. © 1992 Wiley‐Liss, Inc.
Temporal differentiation and migration of substance P, serotonin, and secretin immunoreactive enteroendocrine cells in the mouse proximal small intestine
Authors: Aiken Kimberly D. , Roth Kevin A.
Published: February 2005

Precise spatial interrelationships exist between substance P, serotonin, and secretin containing enteroendocrine cells in the gastrointestinal tract of mice. In the proximal small intestine these products are coexpressed in various combinations in single enteroendocrine cells along the crypt to villus axis in a pattern that suggests the sequential expression of substance P, serotonin, and secretin. In this report we use bromodeoxyuridine (BrdU) and multilabeling immunohistochemistry to define the temporal and spatial interrelationships between substance P, serotonin, and secretin immunoreactive cells in the mouse proximal small intestine. Our findings demonstrate the sequential expression of substance P, serotonin, and secretin in a population of upwardly migrating enteroendocrine cells and, furthermore, identify a population of crypt associated cells coexpressing substance P and serotonin that fails to traverse this pathway. The lack of secretin immunoreactive cells in the crypts suggests that local factors present in the crypts and/or on villi regulate secretin expression. The combined use of BrdU and multilabeling immuno‐histochemistry provides a method for defining enteroendocrine cell differentiation pathways throughout the gastrointestinal tract. © 1992 Wiley‐Liss, Inc.
Segregation and early dispersal of neural crest cells in the embryonic zebrafish
Authors: Raible David W. , Wood Andrew , Hodsdon Wendy , Henion Paul D. , Weston James A. , Eisen Judith S.
Published: February 2005

We have exploited our ability to visualize and follow individual cells in situ, in the living embryo, to study the development of trunk neural crest in the embryonic zebrafish. In most respects, the development of zebrafish trunk neural crest is similar to the development of trunk neural crest in other species: zebrafish trunk neural crest cells segregate from the dorsal neural keel in a rostrocaudal sequence, migrate ventrally along two pathways, and give rise to neurons of the peripheral nervous system, Schwann cells, and pigment cells. However, some aspects of the development of zebrafish trunk neural crest differ from those of other vertebrates: zebrafish trunk neural crest cells are significantly larger and fewer in number than those in avian embryos and the locations of their migratory pathways are slightly different. This initial description of neural crest development in the zebrafish embryo provides the foundation for future experimental studies. © 1992 Wiley‐Liss, Inc.
Cellular contribution of the different regions of the somatopleure to the developing limb
Authors: Geduspan Jene S. , Solursh Michael
Published: February 2005

Regionalization of the presumptive limb region was examined before and at the onset of limb development by means of a variety of transplantation experiments between quail and chick embryos in ovo. The results demonstrate a two‐step process, the first of which is the designation of the region of the somatopleure that would become part of the limb, followed by specification of dorsal and ventral regions of the limb. The medial half of the somatic mesoderm is the region which gives rise to the limb with only a smaller cellular contribution from the lateral half of the somatic mesoderm. The cellular contribution of the medial region of the somatopleure appeared to determine the type of limb formed (i.e., wing or leg). The second process relates to changes in the ability of the somatic ectoderm to undergo extensive lateral displacement with development. Starting at stage 14, the medial and lateral somatic ectoderms maintain their position after transplantation, in contrast to earlier stage limb or flank ectoderms which undergo extensive lateral displacement with development. The positional determination of the dorsal and ventral properties of the medial and lateral ectoderms of the prospective limb region and their distal displacement during limb outgrowth may be important morphogenetic events in limb development. © 1993 Wiley‐Liss, Inc.
Cell interactions influence the pattern of biomineralization in the Ilyanassa obsoleta (mollusca) embryo
Authors: McCain Elizabeth R.
Published: February 2005

Ilyanassa obsoleta larvae have two calcium carbonate‐containing organs, shell and statocyst, which are derived from five micromere cells (2a, 2c, 2d, 3c, 3d). “Internal shell,” an abnormal, internal calcium carbonate mass, was previously observed when cells which normally induce shell and statocyst were removed. This study utilizes multiple‐cell deletions to examine how these calcium carbonate‐producing precursors control the pattern of biomineralization, whether it is in external shell, statocyst, or internal shell. It was demonstrated that internal shell was solely derived from any of these five cells. However, there was a quantitative difference in the frequency of internal shell production depending upon which cells, as well as how many, are deleted. In general, when external shell or statocyst production was diminished, as the result of removing several of the calcium carbonate‐producing cells, internal shell was deposited instead. The presence of internal shell can best be explained as the result of altered interactions between these five cells after one or more have been deleted. Electron diffraction and transmission electron microscopy show that internal shell differs from normal shell in both structure and crystal morphology and it can also be produced by statocyst precursors. Thus, both the deletion and electron microscopy data support the interpretation that the development of internal shell is controlled by shell‐ and statocyst‐producing cells when the cell communication between these cells is disrupted. © 1993 Wiley‐Liss, Inc.
Pattern of expression of transforming growth factor‐β4 mRNA and protein in the developing chicken embryo
Authors: Jakowlew Sonia B. , Ciment Gary , Tuan Rocky S. , Sporn Michael B. , Roberts Anita B.
Published: February 2005

Expression of TGF‐β4 mRNA and protein was studied in the developing chicken embryo using specific cDNA probes and antibodies for chicken TGF‐β4. Expression of TGF‐β4 mRNA was detected by day 4 of incubation (Hamburger and Hamilton stage 22, E4) by RNA Northern blot analysis and increased with developmental age until day 12 of incubation (stage 38, E12) where it was detected in every embryonic tissue examined, with expression being highest in smooth muscle and lowest in the kidney. The steady‐state level of expression of TGF‐β4 mRNA remained relatively constant in most embryonic tissues through day 19 (stage 45, E19). In situ hybridization analysis detected TGF‐β4 mRNA as early as the “definitive primitive streak” stage (stage 4); during neurulation (stage 10), TGF‐β4 mRNA was detected in all three germ layers, including neuroectoderm. Following neurulation, TGF‐β4 mRNA was detected in the neural tube, notochord, ectoderm, endoderm, sclerotome, and myotome, but not dermotome at stage 16. By day 6 of incubation (stage 29, E6), TGF‐β4 mRNA was localized in several tissues including heart, lung, and gizzard. Immunohistochemical staining analysis also showed expression of TGF‐β4 protein in all three germ layers as early as stage 4 in various cell types in qualitatively similar locations as TGF‐β4 mRNA. These results suggest that TGF‐β4 may play an important role in the development of many tissues in the chicken. © 1993 Wiley Liss, Inc.
Type II collagen during cartilage and corneal development: Immunohistochemical analysis with an anti‐telopeptide antibody
Authors: Chen Qian , Fitch John M. , Gibney Eileen , Linsenmayer Thomas F.
Published: February 2005

We have examined the pattern of immunoreactivity of a monoclonal antibody, II‐5B2, with specificity for an epitope which resides within the NH2‐terminal extension peptide (telopeptide) of the avian type II collagen molecule. This epitope is available in regions of matrix where de novo synthesis of the molecule is ongoing, but not where synthesis has ceased and maturation and crosslink formation have occurred. Within the cartilaginous growth plate, the epitope disappears from the matrix soon after the chondrocytes become hypertrophic; within the cornea, the epitope disappears subjacent to the epithelium. The II‐5B2 epitope is not made available by a variety of procedures shown to remove potentially masking substances and to disrupt fibrillar organization. It is rendered available, however, when covalent crosslink formation between collagen molecules is blocked through administration of β‐aminopropionitrile or penicillamine. In contrast, the epitope of another monoclonal antibody against type II collagen, II‐II6B3, which resides in the triple‐helical domain of the molecule, in cartilage is present throughout the growth plate including the hypertrophic zone, and in cornea extends for a considerable distance into the stroma. Thus, it is available for antibody binding regardless of fibril maturation and crosslinking. These data suggest that the II‐5B2 epitope becomes unavailable when the telopeptide becomes cross‐linked. By using these two monoclonal antibodies in serial sections, one can establish the crosslinking pattern of type II collagen in the tissue. This set of antibodies is a potentially useful tool for analyzing normal and abnormal development, remodeling, and repair processes in the skeletal system and in other tissues where type II collagen is involved in organization of the matrix, such as the primary corneal stroma. © 1993 wiley‐Liss, Inc.
Evidence that the border of the neural plate may be positioned by the interaction between signals that induce ventral and dorsal mesoderm
Authors: Zhang Jing , Jacobson Antone G.
Published: February 2005

In the early Xenopus embryo, a quadrant of endodermal cells that have descended from the vegetal dorsal localization in the zygote produces signals that pass into the animal hemisphere and induce dorsal mesoderm from the marginal zone. From the remaining three quadrants of the bordering endoderm, signals pass into the animal hemisphere and induce ventral mesoderm in the marginal region. There is evidence that suggests that these same mesoderm‐inducing signals continue through the plane of the tissue of the animal hemisphere where they may at least begin the processes of neural and epidermal induction by changing the competence of the prospective ectodermal cells, and possibly influencing the early regional biasing of later expression of at least some gene products, such as Epi‐1 whose expression in the future epidermal domain seems specified before gastrulation. We hypothesized that the interaction of the ventral and dorsal signals within the plane of the tissue of the animal hemisphere may position the border of the neural plate. If this is so, then transplantation into the animal pole of cells that signal induction of ventral mesoderm should drive the neural plate boundary back toward the blastopore and shorten the anterior‐posterior axis. Removal of cells that induce ventral mesoderm should result in an axis that is longer than normal. Results of our experiments support these predictions. Also, by late pregastrula stage 9, increasing the ventral signals has no effect. Thus the evidence suggests that the position of the anterior neural plate boundary is established before gastrulation begins by the interaction of the signals that induce the ventral and dorsal mesoderm. © 1993 wiley‐Liss, Inc.
Developmental expression of four novel serine/threonine kinase receptors homologous to the activin/transforming growth factor‐β type II receptor family
Authors: He Wei Wu , Gustafson Michael L. , Hirobe Seichii , Donahoe Patricia K.
Published: February 2005

Serine/threonine kinase transmembrane proteins are a new family of growth factor signal transducers that includes several isoforms of the activin type II receptor and the type II receptor for transforming growth factor‐β. In an effort to clone the receptor for Mullerian inhibiting substance, a member of the transforming growth factor‐β superfamily, oligonucleotide primers designed from conserved regions of these receptors' kinase domains were used for PCR amplification of fetal rat urogenital ridge cDNA. We isolated four novel receptors in this manner (desingnated R1–R4), each of which has structural features of the previously cloned kinases, including a small extracellular ligand‐binding domain, a single hydrophobic transmembrane domain, and an intracellular serine/threonine kinase domain. In addition, each has characteristic kinase subdomains and conserved serine/threonine kinase sequences found in this family. Northern analysis revealed mRNA expression of R1‐R4 in several tissues, including fetal urogenital ridge, testis, and ovary, as well as brain and lung. In situ hybridization further localized R1 to mesenchyme of the 14.5 to 15‐day fetal rat Mullerian duct and to oocytes of preantral and antral follicles, sites that are consistent with the predicted localization of Mullerian inhibiting substance receptor. In addition, R2 localized specifically to seminiferous tubules of the postnatal testis. These newest members of the activin and transforming growth factor‐β type II receptor family should help define the molecular mechanisms by which this ligand superfamily affects cell growth and differentiation via membrane phosphorylation. © 1993 wiley‐Liss, Inc.
Developmental regulation and cell type‐specific expression of the murine γF‐crystallin gene is mediated through a lens‐specific element containing the γF‐1 binding site
Authors: Goring Daphne R. , Bryce Dawn Marie , Tsui Lap‐Chee , Breitman Martin L. , Liu Qiurong
Published: February 2005

The mouse γF‐crystallin gene, one of six differentially regulated members of the γ‐crystallin gene family, is expressed exclusively in central nuclear fiber cells of the adult lens. The expression of this gene is controlled through regulatory elements contained in two upstream enhancers and the proximal promoter. Here we show that while the upstream enhancers and the proximal promoter could each direct gene expression in fiber cells formed at early stages of lens growth and development, cooperation between these elements is required to achieve expression in fiber cells formed at later stages. Evidence is provided that cooperative interaction between these elements modulates gene expression by increasing promoter strength. We also show that sequences within the proximal promoter region that bind lens cell nuclear factor γF‐1 are sufficient to elicit gene expression in central nuclear fiber cells of the adult lens. © 1993 wiley‐Liss, Inc.