bluuebunny/crossref_metadata_2025 huggingface dataset:
Gross anatomy: An outdated subject or an essential part of a modern medical curriculum? Results of a questionnaire circulated to final‐year medical students
Authors: Pabst Reinhard
Published: February 2005

Final‐year undergraduate medical students were given a questionnaire on the gross anatomy curriculum they had experienced in their first year at medical school 5 years earlier. They were asked to evaluate the relevance of the dissection course, lectures and seminars in gross anatomy for clinical courses, clerkships, and everyday practical work on the ward. About two‐thirds of the students found the time spent on 10 different regions in anatomy to be adequate, and a considerable number of students would have liked even more details. The vast majority expressed a wish to repeat topographical anatomy during their clinical teaching. Furthermore, ∼75% of the students showed interest in short, specialized dissection courses during the clinical curriculum. Medical students just before graduation ranked gross anatomy with the dissection course and integrated clinical topics as a keystone for their clinical courses. The results of such surveys should be taken into consideration when discussing modification to teaching gross anatomy or arguing about a balanced dissection course. © 1993 Wiley‐Liss, Inc.
Isolated pancreatic islets of the rat: An immunohistochemical and morphometric study
Authors: El‐Naggar Mostafa M. , Elayat Ahmed A. , Ardawi M. Salleh M. , Tahir Mohammad
Published: February 2005

Although there is a recent increase in the use of the isolated pancreatic islets of the rat in the transplantation and functional studies, there has been no detailed quantitative assessment on the size and cellular constituents of islets after the isolation procedure. The present work was undertaken to study the size classes of the isolated islets and the morphometry of their cellular populations.

Islets of the rat pancreas were isolated by using the intraductal collagenase digestion technique, the most commonly used procedure for the isolation of pancreatic islets. Different endocrine cells of the isolated islets were stained by immunoperoxidase staining techniques. The distribution of the cellular constituents of the isolated islets was similar to that of the intact islets of the normal pancreas; A, D, and PP cells were peripherally arranged around the centrally located B cells. However, morphometric quantitative study showed that the percent volume and percent number of A, D, and PP cells of the isolated islets were lower than those of the corresponding intact ones. Further, the mean true diameter of the isolated islets was lower than that of the intact ones. These data indicate loss of islet cells during the process of isolation. Most of the lost cells were from the periphery of islets. This may provide an explanation for the incomplete metabolic control and recurrence of hyperglycemia encountered after isolated islet transplantation in the treatment of diabetes mellitus. It seems that further refinements of the isolation techniques are necessary to obtain islet tissue with total cellular integrity, before a complete success in transplantation could be achieved. © 1993 Wiley‐Liss, Inc.
Role of mesenchymal cells in the neovascularization of the rabbit phallus
Authors: Hara Kazuo , Doi Yoshiaki , Nagata Naoki , Furukawa Hiroshi , Sagara Tetsuya , Yamamoto Koji , Yokoyama Mitsuru , Yoshizuka Mitsuaki , Fujimoto Sunao
Published: February 2005

The neovascularization of the rabbit phallus at ages between prenatal days 15 and 21 was investigated by light‐ and electron microscopy, computer‐aided light microscopic reconstruction, and immunocytochemistry. The phalli are embedded by an abundance of mesenchymal cells, which are in contact with the neighboring ones or with the endothelial lining of growing capillaires. They often form solid cell cords that eventually make contact with the growing capillaries. The computer‐aided reconstruction of the serial light micrographs reveals that these cell cords are involved in connecting the adjacent capillaries. The incorporation of such mesenchymal cell projections into the endothelial lining, occasionally conjugated with simple attachement devices, is frequently observed by transmission and scanning electron microscopy. The contact areas between the mesenchymal and endothelial cells show immunoreactions of fibronectin.

These results indicate the successive transformation of mesenchymal cells to endothelial cells of the growing capillaries. As endothelial cells of the growing capillaries show mitotic proliferation, such vasoformative mesenchymal cells seem to be involved in the acceleration of the neocapillarization of the rabbit phallus. Fibronectin actively produced in the mesenchymal cells may participate in their migration and the mechanical linkage with the endothelial cells. © 1994 Wiley‐Liss, Inc.
Intramembranous bone matrix is osteoinductive
Authors: Scott Caroline Kelly , Bain Steven Douglas , Hightower James Anderson
Published: February 2005

All known bone‐derived osteoinductive factors have been isolated from endochondral (EC) bones and all initiate bone induction via EC ossification. However, to date no attempt has been made to isolate comparable factors from bones which form initially and completely via intramembranous (IM) ossification. The purpose of this work was to isolate osteoinductive proteins from IM bones. To accomplish this, we extracted proteins from bovine frontal bone matrix (intramembranous origin) using methods previously described for endochondral (EC) bone matrix (i.e., femur). Bone powder (<1 mm) was decalcified and proteins extracted with 4 M guanidine hydrochloride. Ultrafiltration was used to isolate and concentrate a 10–100 kilodalton (kDa) fraction, upon which heparin‐Sepharose (HS) affinity chromatography was performed. HS‐binding (HS‐B) and non‐binding proteins (HS‐NB) were lyophilized with bovine type I collagen (Vitrogen) to form pellets which were implanted subcutaneously in rats. Radiology as well as brightfield, fluorescent, and polarizing microscopy were used to assess the formation of ectopic bone at the site of pellet implantation. In this report we demonstrate that a heparin‐Sepharose binding, osteoinductive factor can be extracted and partially purified from bovine intramembranous bone matrix. This factor has a different sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) banding pattern than a comparable osteoinductive/chondroinductive factor isolated from EC bone. © 1994 Wiley‐Liss, Inc.
Stereological analysis of collagen and elastic fibers in the normal human dermis: Variability with age, sex, and body region
Authors: Vitellaro‐Zuccarello Laura , Cappelletti Silvia , Rossi Vera Dal Pozzo , Sari‐Gorla Mirella
Published: February 2005

Normal human dermis has been analyzed using sterological methods to estimate the quantitative modifications of collagen and elastic fibers in relation to age, sex, and body region. Forty‐five skin biopsies from the trunk or the limbs of 26 males and 19 females of different age were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin. The relative volumes of collagen and elastic fibers were calculated by the point counting method on 1 μm semithin sections. Photographic sampling was performed on four consecutive dermis layers: the papillary layer and three consecutive layers of reticular dermis. The data were subjected to analysis of variance which showed that all the factors studied exert a significant influence on the relative amounts of collagen and elastic fibers. The fractional volume of collagen fibers is constant throughout all dermis layers analyzed and is always higher in females than in males, except for the second and third decades of life. Collagen fiber density increases with age in both sexes up to 30–40 years, when it starts decreasing. Both the relative volumes and the diameters of elastic fibers increase from papillary to deep reticular dermis. In reticular dermis of both sexes there is an increment of elastic fiber density in the first decade of life, followed by a drop particularly marked in males. After 20 years, the relative volume of elastic fibers displays a decreasing trend in females, whereas it increases in males, attaining the highest values beyond the 40s. © 1994 Wiley‐Liss, Inc.
Fibrous tissue on the tibia plateau of the kangaroo. A theory on the pressure absorption of joint surfaces
Authors: Fuss Franz K.
Published: February 2005

The central part of the articular surface on the tibia plateau of Macropus agilis consists of fibrous cartilage of soft consistency and the fiber arrangement is macroscopically visible. The peripheral portions of the plateau are covered by hyaline cartilage but do not communicate with the hyaline articular surfaces of the femur, as they are covered by the menisci. The fibrous cartilage covering of the tibia plateau is a compliant or readily deformed pad that could serve the function of deforming enough under high joint loads to allow surrounding regions of the articular cartilage to share in carrying those loads, thereby magnifying the articular contact surface and decreasing the magnitude of the peak unit loads in the region of the fibrous tissue pad. This pressure‐absorbing mechanism represents the evolutionary response to the higher articular stress resulting from kangaroo locomotion. © 1994 Wiley‐Liss, Inc.
Temporal changes in sarcomere lesions of rat adductor longus muscles during hindlimb reloading
Authors: Krippendorf Beth B. , Riley Danny A.
Published: February 2005

Focal sarcomere disruptions were previously observed in adductor longus muscles of rats flown approximately two weeks aboard the Cosmos 1887 and 2044 biosatellite flights. These lesions, characterized by breakage and loss of myofilaments and Z‐line streaming, resembled damage induced by unaccustomed exercise that includes eccentric contractions in which muscles lengthen as they develop tension. We hypothesized that sarcomere lesions in atrophied muscles of space flown rats were not produced in microgravity by muscle unloading but resulted from muscle reloading upon re‐exposure to terrestrial gravity. To test this hypothesis, we examined temporal changes in sarcomere integrity of adductor longus muscles from rats subjected to 12.5 days of hindlimb suspension unloading and subsequent reloading by return to vivarium cages for 0, 6, 12, or 48 hours of normal weightbearing. Our ultrastructural observations suggested that muscle unloading (0 h reloading) induced myofibril misalignment associated with myofiber atrophy. Muscle reloading for 6 hours induced focal sarcomere lesions in which cross striations were abnormally widened. Such lesions were electron lucent due to extensive myofilament loss. Lesions in reloaded muscles showed rapid restructuring. By 12 hours of reloading, lesions were moderately stained foci and by 48 hours darkly stained foci in which the pattern of cross striations was indistinct at the light and electron microscopic levels. These lesions were spanned by Z‐line‐like electron dense filamentous material. Our findings suggest a new role for Z‐line streaming in lesion restructuring: rather than an antecedent to damage, this type of Z‐line streaming may be indicative of rapid, early sarcomere repair. © 1994 Wiley‐Liss, Inc.
Development of the tendon of todaro during the human embryonic and fetal periods
Authors: Domènech‐Mateu J. M. , Martínez‐Pozo A. , Arnó‐Palau A.
Published: February 2005

This study covers the development of Todaro's tendon during human embryonic and fetal periods. The tendon primordium first appears when human embryos attain a CR length of 22 mm, but it only becomes well‐defined at 24 mm CR length. The tissue that will form the tendon proceeds exclusively from the inferior endocardial cushion. The tendon establishes a close relationship with the base of the septum secundum during its path towards the right venous valve, carrying myocardial tissue out and forming the fasciculus limbicus inferior to muscular tissue. The tendon's relationship with the superior aspect of the atrioventricular node primordium during the first part of its path is of particular interest. The relationship is most intriguing when the node morphology is least defined. This would explain the possible embryogenesis of extra atrioventricular nodes. We also consider Todaro's tendon to be largely responsible for the development of the sinus band which protrudes as a crest inside the right atrium. This band is particularly well‐developed in the fetal heart and provides an explanation for the large sub‐Eustachian sinus cavity. © 1994 Wiley‐Liss, Inc.
Development of cranial flexure and Rathke's pouch in the chick embryo
Authors: Pikalow Amy S. , Flynn Mary E. , Searls Robert L.
Published: February 2005

Experiments were done to investigate the cause of the cranial (mesencephalic) flexure of the chick brain during stages 10 to 14. Measurements of the length and thickness of the roof and floor of the mesencephalon gave values similar to the values obtained previously by others. The labeling index was determined in the roof and floor of the prosencephalon, mesencephalon, and rhombencephalon as a preliminary measure of cell division. The labeling index was about the same in all regions, and was high enough to suggest that most of the cells were dividing. The labeling indices did not suggest that differential growth was caused by differential rates of cell division in the roof and floor of the mesencephalon. It was found through time lapse photography that the foregut and heart remained stationary along the rostrocaudal axis, whereas the prosencephalon moved rostrally and the mesencephalon underwent flexure. Measurements suggested that the neural tube cranial to the otic primordium grew in volume exponentially at a rate consistent with the labeling index. The rostral tip of the neural tube was observed to be linked to the rostral tip of the foregut by the ectoderm that formed Rathke's pouch at the neural tube and the pharyngeal membrane (prospective stomodeum) at the foregut. As the neural tube grew in length, the link between the neural tube and the foregut did not. We suggest that because of this link, the growing neural tube had to bend around the foregut, forming the cranial flexure, and the ectoderm folded where it attached to the prosencephalon, forming Rathke's pouch. © 1994 Wiley‐Liss, Inc.
Insertional mutation that causes acrosomal hypo‐development: Its relationship to sperm head shaping
Authors: Russell Lonnie D. , Ying Li , Overbeek Paul A.
Published: February 2005

A family of transgenic mice (OVE 219) was generated by microinjection of a tyrosinase minigene (Ty811C). The transgenic mice demonstrate an atypical and variable coat color pattern and the homozygous males show abnormalities of spermatogenesis that are variably expressed from animal to animal. Heterozygous mice proved to have normal spermatogenesis and along with non‐transgenic mice were used as controls to study the abnormalities in spermatogenesis in OVE 219 homozygous males. These abnormalities shed light on the features controlling normal spermatogenesis. In some homozygous males early spermiogenesis was disrupted as the flagellar microtubules became disorganized within the flagellar process. What appeared to be crystalline tubulin was noted within some of the rounded flagellar processes. Sperm with this defect did not develop a flagellum. In other homozygous males defects were apparent by step 6 or 7 of spermiogenesis when the acrosome did not grow and spread over the nucleus as noted in control animals. The modified nuclear envelope underlying the acrosome continued to develop and spread well beyond one margin of the acrosome. Since the modified nuclear envelope grew independently of the acrosome, the acrosome was not the controlling factor in determining the spread of the modified nuclear envelope. Micrographs revealed that Sertoli ectoplasmic specialization failed to form over most regions of the spermatid head lacking a normal acrosome. In homozygous males, the manchette took origin (proximally) in close relation to the modified nuclear envelope and never in relation to the edge of the spreading acrosome, a feature indicating that manchette placement was influenced by the position of the modified nuclear envelope and not the edge of the acrosome. Thus the modification in the nuclear envelope may be the primary event to signal acrosomal spread and manchette development. In spermatids where the manchette developed from an ectopic site, the result was abnormal caudal head shaping. In some spermatids a portion of the manchette was lacking. When this occurred the caudal head was rounded in the region of the missing manchette. In a minority of spermatids there was no evidence for a manchette. The entire caudal head was gently rounded. These data support the growing body of evidence that the caudal sperm head is shaped, in part, by the manchette. The OVE 219 family of mice provides a useful model to understand the processes involved in periods of spermiogenesis that are critical to development of a normally shaped sperm head. © 1994 Wiley‐Liss, Inc.
Quantitative study of the apical nerve fibers of adult and juvenile rat molars
Authors: Naftel John P. , Bernanke Jayne M. , Qian Xiao‐Bing
Published: February 2005

The rat molar has become an important model for studies of interactions between nerves and the pulp‐dentin complex, yet there is only limited quantitative information on the number and size distribution of axons entering the roots of this tooth. This study was undertaken to provide such a detailed characterization of the apical innervation of the rat molar. An additional objective was to compare the apical nerve composition of young, recently erupted rat molars with that of mature teeth in order to determine whether there is ongoing maturation of the innervation after the teeth have attained functional occlusion.

A complete census was made of the nerve fibers entering the roots of both mature and recently erupted juvenile mandibular first molars in Sprague‐Dawley rats. Each of the four roots of the first molars was processed for electron microscopy of thin sections near the apex.

The majority of intradental nerve fibers entered the molar via the two larger (mesial and distal) roots. Within the apical root pulp, most, but not all, axons occurred within well‐defined fascicles associated with blood vessels. Molars from adult animals (age 4 months) had a mean total of 232 (S.D. = 49, N = 7 teeth) myelinated fibers and 806 (S.D. = 143) unmyelinated axons entering the four roots. Fibers exceeding the Aδ size range (circumference ≥ 19 μm) accounted for only 4% of the myelinated axons at the apex. Molars from juvenile animals (age 4 weeks) had fewer myelinated fibers (mean 176, S.D. 18, N = 8), but more unmyelinated axons (mean 1,174, S.D. 160) than adults. The mean ratio of unmyelinated axons to myelinated axons was 6.6:1 for juveniles compared to 3.5:1 for adults. Juvenile teeth contained no myelinated fibers that exceeded 19 μm in circumference.

These results indicate that the innervation of the rat molar resembles that of teeth of non‐rodent mammals in that (1) innervation density is high, (2) there is a high ratio of unmyelinated axons, and (3) most of the myelinated fibers are of thin caliber. Furthermore, it appears that after the molar erupts, maturation of the nerve fiber composition continues with processes that include both a marked decrease in the number of unmyelinated axons and an increase in the number and size heterogeneity of myelinated fibers. © 1994 Wiley‐Liss, Inc.
Myocardial enlargement in defective heart development
Authors: Creazzo Tony L. , Burch Jarrett , Redmond Shannon , Kumiski Donna
Published: February 2005

Background: The cardiac neural crest (neural crest extending from the mid‐otic placode to the caudal region of somite 3) provides ectomesenchymal cells that contribute to aortic arch development and are essential for aortico‐pulmonary septation of the outflow tract. Bilateral ablation of the cardiac neural crest in the chick embryo, prior to migration, leads to aortic arch anomalies and failure of septation of the cardiac outflow tract, which produces a severe defect known as persistent truncus arteriosus (PTA). Altered hemodynamics resulting from abnormal aortic arch artery development and PTA and other unknown factors related to the absence of neural crest, are likely to alter the developmental history of the myocardium.

Methods: In this study the wet and dry weights of ventricles and whole embryos, the total number of myocytes per ventricle and the myocyte density (number of myocytes per unit volume of ventricular myocardium) were compared in control (unwindowed eggs), sham‐operated and cardiac neural crest ablated chick embryos at day 11 of incubation.

Results: We found that the wet and dry weights of ventricles from hearts with PTA were not different from normal hearts in control and sham‐operated embryos. However, the embryos with PTA weighed less than embryos with normal hearts. Thus, the ventricle to embryo weight ratios were greater in embryos with PTA compared to control and sham‐operated embryos for both wet (14 and 20%, respectively) and dry (30 and 59%) weights. The data further implied that more water was present with respect to body weight in comparison with sham‐operated and control embryos which indicated that the embryos with PTA were edematous. The total number of myocytes and the number of myocytes per unit volume were not different when comparing sham‐operated with PTA. Further, there was no indication that the myocardium from hearts with PTA was abnormal despite the small size and edema of the embryos.

Conclusions: It appears that hemodynamic stresses, resulting from the structural defects produced by neural crest ablation, are insufficient to increase heart growth, although cardiac function is depressed as evidenced by edema and failure of the embryo to thrive. © 1994 Wiley‐Liss, Inc.
Light microscopic studies of pedicle and early first antler development in red deer (Cervus elaphus)
Authors: Li Chunyi , Suttie James M.
Published: February 2005

Background: Although it is known that deer antlerogenic potential resides in the periosteum of an antlerogenic region and antler forms through modified endochondral ossification, how a deciduous antler forms histologically through a permanent pedicle from the periosteum has not been reported.

Methods: Histogenesis of the pedicle and the early first antler in red deer was systematically examined using light microscopy techniques.

Results and Conclusions: At the pre‐pedicle stage, the frontal lateral crest (under 5 mm in height) consisted horizontally of antlerogenic periosteum and underlying cancellous bone. Both the cellular layer (3.74 times, P<0.01) and the fibrous layer of the antlerogenic periosteum were much thicker than those of the margin of the antlerogenic region or the facial periosteum. The crest was formed through intramembranous ossification. When the pedicle began to develop (5–15 mm in height), some discrete clusters of mature chondrocytes appeared in the bony trabeculae, which signified the beginning of the transition of the ossification pattern from the intramem branous to the endochondral. The pedicle consisted of three portions from distal to proximal, periosteum/perichondrium, osseocartilaginous tissue, and osseous tissue. When the pedicle became visible (about 20 mm in height), it consisted of the same three portions as the pedicle initiation stage, but the osseocartilaginous portion was expanded compared to the initiation stage and the cartilaginous proportion increased distally. When the pedicle grew to 25–40 mm in height, continous cartilaginous trabeculae appeared under the apical perichondrium. The pedicle consisted of four portions from distal to proximal: perichondrium, cartilaginous tissue, osseocartilaginous tissue, osseous tissue. It was formed through endochondral ossification. All these ossification pattern changes could not be seen externally as the overlying integument was characterised by typical scalp skin. When the pedicle grew to about 60 mm in height, antler tissue was visually apparent at the apex as the hair type changed from scalp hair to the velvet‐like hair of growing antler. However, this transformation could not be distinguished internally as the inside tissues were all continuous between pedicle and antler. Therefore, the histogenesis of the deer pedicle and the first antler originated from the antlerogenic cells and covered two phases: an internal phase through which pedicle was formed and an external phase which signalled the beginning of antlerogenesis. © 1994 Wiley‐Liss, Inc.
Shoulder region of the rat: Anatomy and fiber composition of some suprascapular nerve branches
Authors: Norlin R. , Hoe‐Hansen C. , Öquist G. , Hildebrand C.
Published: February 2005

Background: The pathophysiology of chronic supraspinatus tendinitis is not fully understood. This may be due to the scarcity of experimental studies on this issue.

Methods: In search for a system suitable for experimental analysis, the present study describes the relevant gross anatomy of the rat shoulder region (dissection), and examines the fiber composition of relevant suprascapular nerve branches (electron microscopy, selective denervations).

Results: The rat shoulder region is similar to the human shoulder in terms of gross anatomy. The average suprascapular nerve (SSC) is derived mainly from the spinal cord segment C5 and contains 3,435 axons, 74% of which are unmyelinated. The supraspinatus branch (SSP) contains 627 fibers. Of the SSP fibers, 52% are myelinated, including 32% motor and 20% sensory axons. Of the C‐fibers in the SSP 16% are sympathetic efferents and 32% are sensory. Many of the latter disappear after neonatal capsaicin treatment. The SSC emits a subacromial articular branch (ART), with some 260 axons, about 90% of which are unmyelinated. The myelinated ART fibers are sensory, and of the unmyelinated ones about 24% are sympathetic efferents and 66% are afferents. The latter resist neonatal capsaicin treatment.

Conclusions: In view of the anatomy of the supraspinatus muscle, of the subacromial space, and of relevant nerves, the rat shoulder should be appropriate for experimental studies on inflammatory conditions in the subacromial space. © 1994 Wiley‐Liss, Inc.
Porphyrin accumulation in the harderian glands of female Syrian hamster results in mitochondrial damage and cell death
Authors: Antolín Isaac , Uría Higinio , Tolivia Delio , Rodríguez‐colunga María J. , Rodríguez Carmen , Kotler MóNica L. , Menéndez‐peláez Armando
Published: February 2005

Background: The Harderian glands of female Syrian hamsters contain very high concentrations of protoporphyrin (in the range of μg per mg of tissue) which accumulate in the tubulo‐alveoli of the gland. We have studied the process of synthesis, accumulation, and secretion of this cyclic compound by the secretory cells of the hamster Harderian glands.

Methods: The animals used were female Syrian hamster of 15, 35, 75, 180, and 360 days of age. Items first examined were (1) percentage of the “clear cells,” (2) area occupied by intraluminal porphyrins, and (3) histological characteristics of “clear cells” by light and transmission electron microscopy (TEM). In a second study the total content of porphyrins was determined. Finally, the levels of mRNA for the enzyme aminolevulinate synthase (ALV‐S) were measured.

Results: In the glands of female hamsters, both the tissue concentration and the intraluminal area occupied by protoporphyrin correlate with the appearance of a special type of cell (clear cells) which show signs of cell degeneration. In addition, the expression of the gene for ALV‐S, which is the limiting enzyme in porphyrin production, also parallels the relative number of clear cells. Analyzed under TEM, these clear cells display dilated mitochondria and short and swollen endoplasmic reticulum cisternae. In a late phase of necrosis, the nuclear envelope appears disorganized with scarce chromatin. The mitochondria undergo complete destruction, resulting in electron‐dense bacillar formations which progressively coalesce in large and dense areas of protoporphyrin. The cell dies after this accumulation, being secreted by a “cytogen” mechanism.

Conclusions: In view of our results, the Harderian gland of female Syrian hamster may provide a useful model for the study of the mechanism by which the anomalous accumulation of protoporphyrin induces cell damage in human protoporphyria. © 1994 Wiley‐Liss, Inc.
Differences in osteonal micromorphology between tensile and compressive cortices of a bending skeletal system: Indications of potential strain‐specific differences in bone microstructure
Authors: Skedros John G. , Mason Mark W. , Bloebaum Roy D.
Published: February 2005

Background: It has been hypothesized that bone has the capacity to accommodate regional differences in tension and compression strain mode and/or magnitude by altering its osteonal microstructure. We examined a simple cantilevered bone to determine whether regional differences in particular strain‐related features are reflected in the microstructural organization of compact bone.

Methods&Results: The artiodactyl (e.g., sheep and deer) calcaneus has a predominant loading condition which is typified by prevailing compressive and tensile strains on opposite cortices, and variations in strain magnitudes across each of these cortices. Microscopic examination showed osteon density and cortical porosity differences between tension (caudal) and compression (cranial) cortices, averaging 11.4% more osteons in the compression cortex (P< 0.01) and 80.2% greater porosity in the tension cortex (P< 0.01). There is 43.5% more interstitial bone in the compression cortex (P< 0.01). Osteons in the compression cortex also have smaller areas in contrast to the larger area per osteon in the tension cortex. Although no definite transcortical gradient in osteonal density or cortical porosity is found, fractional area of interstitial bone is largest and osteon population density is lowest in the endocortical regions of both tension and compression cortices. The endocortical regions also have greater porosity than their corresponding middle and pericortical regions (P< 0.01).

Conclusions: These osteonal microstructure and cortical porosity differences may be adaptations related to regional differences in strain mode and/or strain magnitude. This may be related to the disparity in mechanical properties of compact bone in tension vs. compression. These differences may reflect a capacity of bone to process local and regional strain‐related information. © 1994 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public dotmain in the United states of America

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Perspectives: A vital biomechanical model of synovial joint design
Authors: Frost Harold M.
Published: February 2005

Making a durable joint requires adapting the one present at birth to its subsequent mechanical usage and then maintaining it. The total loads on a joint's momentarily loaded area plus the size of that area determine the unit loads on its articular cartilage and subchondral bone. Given those facts, this model suggests the following.

For adaptaion: As is true for bone, a threshold range of unit loads that could turn cartilage modeling ON would lie below this tissue's microdamage threshold. When a joint's unit loads rose to that modeling threshold, chondral modeling would begin enlarging the momentarily loaded area to reduce and keep the unit loads on it below the microdamage thresholds of the bone and cartilage supporting that area.

For maintenance: Maintenance activities would control the stiffness of cartilage and bone, which would also affect a joint's momentarily loaded area. These activities would usually repair whatever microdamage normally arises in those tissues, and could modify their microdamage thresholds too.

In children, modeling and maintenance in bone and cartilage would function effectively. In adults chondral modeling becomes ineffective, but maintenance activities in bone and cartilage would remain effective, and likewise for modeling in the subchondral bone.

This model assigns special importance in joint design to the stiffness of bone, cartilage, and ligament (as distinguished from their strength), to the typical largest unit: loads applied to them by a subject's usual weekly physical activities, and to their microdamage. © 1994 Wiley‐Liss, Inc.
Enrichment of glutamate immunoreactivity in lemniscal terminals in the ventropostero lateral thalamic nucleus of the rat: An immunogold and WGA‐HRP study
Authors: De Biasi Silvia , Amadeo Alida , Spreafico Roberto , Rustioni Aldo
Published: February 2005

Background: The ventropostero lateral nucleus (VPL) is a thalamic somatosensory center receving inputs from limbs and trunk; some of this input is via terminals of the dorsal column medial lemniscal pathway. These fibers convey non‐noxious somesthesic information.

Methods: In this study the neurochemical content of lemniscal afferents in VPL of rats was investigated at the electron microscopic level by combining anterograde transport of horseradish peroxidase conjugated to wheat germ agglutinin, injected in the dorsal dorsal column nuclei, with postembedding immunogold labeling for glutamate (Glu).

Results: Anterograde labeling in VPL was detected only in myelinated axons and in large terminals containing round synaptic vesicles, interpreted as lemniscal afferents. Quantitative evaluation of gold particle density showed enrichment of Glu immunolabeling in the identified lemniscal terminals with respect to other neuronal profiles. Observation of serial sections immunoreacted for Glu demonstrated consistency of labeling, whereas in alternate sections immunoreacted for Glu and for the inhibitory amino acid GABA these two antigens were always present in distinct types of terminals.

Conclusions: These findings are in agreement with several lines of evidence, obtained with different experimental approaches, supporting the hypothesis that Glu plays a major role in conveying sensory stimuli to the thalamus from second order neurons in the dorsal column nuclei. © 1994 Wiley‐Liss, Inc.
Immunohistochemical evidence of neurons with GHRH or LHRH in the arcuate nucleus of male mice and their possible role in the postnatal development of adenohypophysial cells
Authors: Sasaki Fumihiko , Kawai Takao , Ohta Mitsuaki
Published: February 2005

Background: The neonatal administration of monosodium L‐glutamate (MSG) has been used in investigations of the possible role of the arcuate nucleus in neuroendocrine regulation during postnatal development. We used this method to examine whether the mouse arcuate contained cell bodies immunoreactive with antisera to growth hormone releasing hormone (GHRH) or luteinizing hormone releasing hormone (LHRH), and whether these hypothalamic peptides affect synthesis and secretion of growth hormone and gonadotropin and the testis.

Methods: The hypothalamus, pituitary, and testes of adult male mice treated with MSG during the neonatal period were fixed in Bouin's fluid or 10% neutral formalin. The hypothalamus was used in immune staining, the pituitary was used in both morphometry and immune staining, and the testis was stained with hematoxylin and eosin.

Results: Body weights in control and treated mice were not different. The treated mice had more subcutaneous adipose tissue and a shorter body than the control mice. The testes were heavier in the controls. Many perikarya immunoreactive with antisera to GHRH or LHRH were found in the arcuate nucleus in control mice, but few such perikarya were found in this nucleus in treated mice. The size of the anterior lobe and the number and size of GH cells, follicle stimulating hormone (FSH) cells, and prolactin (PRL) cells in treated mice were less than those of control mice.

Conclusions: GHRH and LHRH neurons in the arcuate nucleus in male mice may cause body and testis weight to increase via GH and LH cells, respectively, in the adenohypophysis during postnatal development. There are some differences in the hypothalamo‐pituitary‐testis axis of mice and rats. © 1994 Wiley‐Liss, Inc.
Type III collagen is a major component of interodontoblastic fibers of the developing mouse molar root
Authors: Ohsaki Yasuyoshi , Nagata Kengo
Published: February 2005

Background: Recently, collagenous interodontoblastic fibers (IOF) were reported in some particular developmental stages and/or locations of the tooth. However, it remained unclear whether these fibers were identical to so‐called von Korff fibers.

Methods: To clarify this issue, we examined the developing mouse molar by three‐dimensional reconstruction of 8 confocal images within a 6 μm‐thick section using laser scanning confocal microscopy, and confirmed our findings using immunoelectron microscopy.

Results: In the root pulp during circumpulpal dentin formation, the IOF stained weakly for type I collagen, but stained strongly for type III collagen by a double‐staining technique. It could be clearly seen that many immunoreactive fibers ran spirally among the odontoblasts and entered the predentin. This distribution pattern of IOF was similar to that of the classical von Korff fibers. Furthermore, the existence of anti‐type III reactive collagen fibrils between odontoblasts was confirmed, whereas IOF were not observed in the coronal pulp during circumpulpal dentin formation.

Conclusions: This study presents for the first time, immunohistochemical observations which demonstrate the presence of IOF at least during root circumpulpal dentin formation and which reveal that type III collagen is a major component of IOF. © 1994 Wiley‐Liss, Inc.
Developmental expression of sulfated glycoprotein‐2 in the epididymis of the rat
Authors: Hermo L. , Barin K. , Oko R.
Published: February 2005

Background: Sulfated glycoprotein‐2 (SGP‐2), also designated as clusterin, is a protein secreted by the epididymis and which binds to spermatozoa. In adult rats it is secreted at high levels by principal cells of the distal initial segment, intermediate zone and caput epididymidis, and at relatively lower levels by principal cells of the corpus and cauda epididymidis. The objective of this study was to correlate the developmental events in the maturation of the epididymis with the timing of SGP‐2 expression in order to evaluate the testicular or epididymal factors which may regulate it.

Methods: Our approach was to follow and compare the developmental expression of SGP‐2 by immunocytochemistry in normal untreated control rats and rats whose efferent ducts were ligated on day 15 and examined at different postnatal ages thereafter.

Results: In control animals, SGP‐2 expression in principal cells of the distal initial segment, intermediate zone, and caput and distal cauda epididymidis, as characterized in normal 90‐day‐old adult animals, was attained between postnatal days 39 and 49. However, only by postnatal day 56 did SGP‐2 display in the corpus and proximal cauda the characteristic secretory pattern found in adult rats. In contrast, in efferent duct ligated rats examined at postnatal day 64, SGP‐2 was absent in principal cells of the corpus and proximal cauda epididymidis but continued to be secreted by the distal initial segment, intermediate zone, and caput and distal cauda epididymidis. Furthermore, unlike the case in control rats, SGP‐2 was secreted at high levels by the principal cells of the proximal initial segment. Thus during normal postnatal development, in the proximal initial segment, the production of SGP‐2 is suppressed by luminal factors originating from the testis, while in the distal initial segment, intermediate zone, and caput epididymidis, it is unaffected by these factors. On the other hand, the production of SGP‐2 in the corpus and proximal region of the cauda epididymidis is normally stimulated by luminal factors originating from the testis, while in the distal cauda, it is unaffected by these factors.

Conclusions: Our results thus show a differential regulation of SGP‐2 expression in principal cells of the proximal versus distal regions of the epididymis and even within subdivisions of each region. In some regions of the epididymis, SGP‐2 production appears to be unaffected by luminal factors originating from the testis, while in other regions it is either inhibited or stimulated by these factors. © 1994 Wiley‐Liss, Inc.
Embryological development of the arterial system of the forelimb in Tupaia
Authors: Matsumoto Shin , Kuhn Hans‐Jürg , Vogt Hermann , Gerke Michael
Published: February 2005

Background: The arterial system of the upper extremities in man shows drastic developmental changes and many individual variations related to interspecific variations in primates. The ontogenetic development in Tupaia was examined from the viewpoint of comparative embryology.

Methods: Histological specimens of 39 embryos were observed and reconstructed in three dimensions using a computer program. Four adult animals were dissected and examined with angiography to ascertain the end stage of development.

Results: At the proximal end of the upper arm the deep brachial artery appears first as a concomitant vessel with the radial nerve. It becomes reduced in size and is succeeded by the posterior circumflex humeral artery, which is accompanied initially by the axillary nerve and finally by the radial nerve. The main arterial passageway to the fingers consists of the brachial and interosseous arteries during early development. The superficial brachial artery and median artery are formed later, and their connection becomes the main route of blood supply for the finger arteries up to the adult stage. The ulnar artery is formed at the end of arterial development to form the ulnar end of the superficial palmar arch. The superficial antebrachial arteries are also recognized.

Conclusions: All the arterial elements of the forelimb in Tupaia are observed in a variety of primates, including man, and the characteristics of Tupaia are thought to represent the primitive conditions of the common ancestor of tree shrews and primates. © 1994 Wiley‐Liss, Inc.
Ultrastructure of melanocytes in the dark cell area of human vestibular organs: Functional implications of gap junctions, isolated cilia, and annulate lamellae
Authors: Masuda Masazumi , Yamazaki Kazuto , Kanzaki Jin , Hosoda Yasuhiro
Published: February 2005

Background: It is known that melanocytes exist in almost all parts of the inner ear, such as the cochlear duct, stria vascularis, Reissner's membrane, modiolus, vestibular organs in the region surrounding the cristae and maculae, semicircular canals, and pars rugosa of the endolymphatic sac. But there have been few studies using human materials, because of the difficulty of obtaining materials. We attempted to investigate the detailed ultrastructure of melanocytes in the vestibular organs of human inner ear.

Methods: Eight surgical specimens obtained from patients with vestibular schwannoma were studied by light microscopy and electron microscopy.

Results: Melanocytes were found in the subepithelial layer of the dark cell area. Melanocytes had round or spindle‐shaped nuclei and clear cytoplasm with brown pigment granules. Besides melanocytes, there were melanophages, fibroblasts, and small blood vessels. Through electron microscopy we found melanocytes with round‐shaped melanosomes in various stages of pigmentation, well‐developed Golgi apparatus and endoplasmic reticulum in the cytoplasm, and many cytoplasmic processes. Gap junctions were occasionally found between the cytoplasmic processes. And there were pinocytotic vesicles just under the limiting membrane of melanocytes, and intermediate filaments were abundant in the cytoplasm. Isolated cilia of melanocytes, annulate lamellae, and fusiform banded structures in the connective tissue area around melanocytes were found.

Conclusions: Melanocytes in human vestibular organs actively synthesize melanosomes. Frequent findings of isoalted cilia and fusiform banded structures and the incidental existence of annulate lamellae may be an indicator of this metabolically activated state of melanocytes. Moreover, monitoring environmental changes by isolated cilia, melanocytes in the human inner ear could act not only as one cell but also as a group to achieve their physiological functions by means of information transmission through gap junctions. © 1994 Wiley‐Liss, Inc.
Anatomical localization of immunoreactive oxytocin and β‐endorphin in the bovine neurointermediate lobe
Authors: McDonnell John J. , Frappier Brian L. , Amann John F.
Published: February 2005

Background: Beta‐endorphin and oxytocin immunocytochemical localization were examined in the neurointermediate lobe (lobus nervosus and pars intermedia) of the bovine hypophysis in order to describe the anatomical distribution of these two neurointermediate lobe hormones.

Methods: Twenty‐seven bovine hypophyses were collected from slaughterhouse animals (seven mature lactating cows, eleven mature nonlactating cows, three nulliparous heifers, and six steers). Hypophyses were immunostained for oxytocin‐containing fibers and β‐endorphin‐secreting cells by using the avidin biotin‐immunoperoxidase method. The distributions of β‐endorphin–positive cells and oxytocin‐positive nerve fibers were plotted on projected outlines of the hypophyses. Immunoreactive staining intensity was graded numerically as weak, moderate, or heavy by three individuals who had no knowledge of the animals' physiological status.

Results: Oxytocin immunoreactivity was confined to the lobus nervosus while β‐endorphin staining was confined to the pars intermedia and the pars distalis. However, oxytocin immunopositive neurosecretory terminals were distributed more heavily in that part of the lobus nervosus bordering the pars intermedia than in the center of the lobe.

Conclusions: These results were similar to those previously reported for the rat (Swaab et al., 1975; J. Neural Transm., 36:195–215; Deftos and Catherwood, 1980; Life Sci., 27:223–228). © 1994 Wiley‐Liss, Inc.
Ultrastructure and immunohistochemistry of the embryonic type of fat identified in the human infant breast
Authors: Anbazhagan Ramaswamy , Gusterson Barry A.
Published: February 2005

Abstract: In this paper we describe the light and electron microscopic appearance of the embryonic type of fat in human infant breast, together with immunocytochemical findings. This fat tissue was composed of numerous capillaries surrounded by a mixed population of undifferentiated mesenchymal cells and preadipocytes at various stages of differentiation. The preadipocytes were characterised by a number of cytoplasmic processes, varying numbers of lipid droplets, and an envelope of electrondense material outside the cell membrane. Immunocytochemistry showed a characteristic distribution of collagen type IV adjacent to and vimentin and S100 protein within the preadipocytes. This is the first report of the ultrastructure of the human mammary embryonic type of fat. The possible role of the embryonic type of fat in the development and growth of the human breast is discussed. © Wiley‐Liss, Inc.