bluuebunny/crossref_metadata_2025 huggingface dataset:
Spaced serial section analysis of the avian muscle spindle
Authors: Hikida Robert S.
Published: February 2005

Muscle spindle ultrastructure of the extensor digitorum communis of pigeons was studied using spaced serial sections. The intrafusal fibers extended well beyond the ensheathing capsule, after which they became disoriented and often fused with each other before terminating on the connective tissue of extrafusal fibers. Several extracapsular fibers contained macrofibrils which were about 0.1 μm in diameter and contained several dozen smaller (10 nm) subunits. Intrafusal fibers commonly formed close attachments with one another for short or extended (240 μm) lengths. A basal lamina was absent between regions of pairing, and a myosatellite cell lay at the border of the coupled region. Several fibers could be coupled together in a single cross section; fibers coupled together, separated, and either recoupled or became associated with other fibers along the length of a spindle.

Profiles of sensory terminals and sensory satellite cells alternated to form a smooth‐contoured surface over most of the fiber cross section in the equatorial region. The sensory terminals contained many mitochondria, lysosomes, and clear and dense core microvesicles. Both the terminals and sensory satellite cells formed desmosomelike junctions with the intrafusal fiber. A crescentic collagen sheath covered that portion of the fiber cross section containing the sensory terminal‐satellite cell complex. Inner capsule cells surrounded the entire assembly in the equatorial region.

The basal lamina thicknesses differed over the naked intrafusal fiber compared to that portion covered by the sensory terminal or sensory satellite cell. The thickness was more than doubled over the latter regions, indicating that the basal lamina over these areas was a product of the fused intrafusal fiber and sensory terminal and/or sensory satellite cell basal laminae. These are discussed in terms of intrafusal fiber degeneration and regeneration.
Electron microscopic immunocytochemical localization of glucagon and pancreatic polypeptide in rat pancreas: Characterization of a population of islet cells containing both peptides
Authors: Cheng Kaung Hue‐Lee
Published: February 2005

The distribution of glucagon and pancreatic polypeptide was studied immunocytochemically in rat pancreas at both light and electron microscopic levels. My earlier observation that these two peptides are distributed in three cell types—cells containing glucagon, cells containing pancreatic polypeptide, and cells containing both—was confirmed at the electron microscopic level. In the glucagon‐pancreatic polypeptide cells, the immunoreactivities of the two peptides were present in the same secretion granules. In addition, these glucagon and pancreatic polypeptide‐containing granules were morphologically distinct from glucagon granules but similar to pancreatic polypeptide granules and somatostatin granules.
Nuclear uptake of 1,25‐dihydroxyvitamin D3 in developing rodent teeth: An autoradiographic study
Authors: Kim Y. S. , Clark S. A. , Stumpf W. E. , DeLuca H. F.
Published: February 2005

Target cells for 1,25(OH)2 vitamin D3 metabolites are identified in developing rodent teeth by the use of thaw‐mount autoradiography. Following the injection of [26, 27‐3H]‐1,25(OH)2 vitamin D3 into 18‐day‐ and 20‐day‐old fetal rats and neonatal mice, nuclear concentration of radioactivity is found in different cell types. In incisors of both animal groups, strong nuclear labeling is present predominantly in pulp cells, while relatively weakly labeled cells are found in the layers of odontoblasts, ameloblasts, and stratum intermedium. In molars, nuclear labeling is absent in fetal rats, but is present in 2‐day‐old neonates in pulp cells and cells in the layers of stratum intermedium of the first molars, but not in the second molars. The absence of labeled pulp cells in the progenitor regions of incisors and in molars of 20‐day‐old fetal rats, and differential ontogenic appearance of labeled pulp cells in molars, indicates that there is a critical period of receptor emergence. The finding that labeled pulp cells exist in the regions of incisors and molars where secretory odontoblasts are present suggests that nuclear uptake of 1,25(OH)2 vitamin D3 is related to cell maturation and differentiation, and topographically related to the formation of dentin. The results further suggest that, in contrast to bone, the predominant effect of 1,25(OH)2 vitamin D3 is not on tooth cells which are directly involved in the formation of calcified tissue, i.e., ameloblasts and odontoblasts, but rather on supporting tissues such as pulp cells and stratum intermedium.
Mucosubstance histochemistry in control and acid‐stressed epidermis of brown bullhead catfish, lctalurus nebulosus (LeSueur)
Authors: Zuchelkowski Edwin M. , Pinkstaff Carlin A. , Hinton David E.
Published: February 2005

Glycoprotein components of epidermal mucous cells in control (pH 6.8) and acid‐stressed (pH 5.8, 4.8, 4.0) brown bullhead catfish were studied by histochemical and autoradiographic methods. Following exposure to acid, increased numbers of epidermal mucous cells were noted in all tissue sites studied, particularry dorsal and ventral skin. Mucous cells of control fish and acid‐stressed (pH 5.8) fish contained a mixture of neutral and acidic mucosubsf ances, the latter including both sialomucins and sulfomucins, with sialomucins predominating. An apparent shift toward increased sulfomucin production was observed in skin from fish exposed to pH 4.8 and 4.0. In addition, autoradiographic studies using 35S showed increased labeling of mucous cells in acid‐exposed (pH 4.0) epidermis, offering further support for a shift toward sulfomucin production in acid‐stressed fish. Absence of appreciable sulfomucin production in younger fish (<1 year old) suggested that this shift may be partly age‐dependent. The functional significance of increased sulfomucin production in acid‐stressed epidermal mucous cells is uncertain but may be related to maintenance of ionic equilibrium.
Effects of sexual rest or sexual activity on the structure and function of the ventral prostate of the rat
Authors: Aumüller G. , Braun B. E. , Seitz J. , Müller T. , Heyns W. , Krieg M.
Published: February 2005

Previous studies have shown that sexual activity increases the weight of the accessory sex glands significantly, while the organ weights correlate inversely with the assayable androgen receptor concentrations in the prostate of sexually active versus sexually resting rats. In an effort to determine the structural basis of this phenomenon, the ventral prostates of adult rats kept with female rats for 4–6 months (HE‐rats) were compared to those kept in groups of 5 males in one cage (HO‐rats) for the same period. As an estimate of the secretory function of the gland the concentration of prostatic binding protein (PBP) was determined in prostatic cytosols using a highly specific ELISA. Catecholamines were measured by means of HPLC and subsequent electrochemical detection. Morphological studies included immunocytochemistry of PBP, visualization of adrenergic nerves, stereological analysis of stromal and glandular compartments of the prostate, and electron microscopy of the epithelium.

The main findings were as follows: (1) The prostates of HE‐rats were 35% heavier than those of the HO‐rats. (2) The content in secretion was in the same range in both HE‐rats and HO‐rats (1.5 and 1.44 mg PBP per 1 mg DNA). (3) Immunocytochemistry and electron microscopy demonstrated a very homogeneous secretion within the glandular lumen of HO‐rats with a diminished amount of secretory material within the glandular cells.

In HE‐rats the glandular lumina were clearly larger in diameter and intraluminal secretion was less homogeneously stained. The height of the epithelium was increased and the individual secretory cells contained several secretory granules. Within the prostatic stroma the profiles of adrenergic nerves were more numerous in HE‐rats, and a greater total amount of noradrenaline was present. At the fine structural level signs of enhanced membrane turnover, such as lysosomal structures, were prominent in prostatic epithelium of HE‐rats, while in HO‐rats mostly dense bodies were observed. The results indicate that sexual activity results in the functional adaption (activity hypertrophy) of the prostate as a result of nerve‐associated control of glandular activity.
Interstitial compartment pathology and spermatogenic disruption in testes from impotent diabetic men
Authors: Cameron Don F. , Murray Frederick T. , Drylie David D.
Published: February 2005

Studies utilizing animal models of diabetes suggest that diabetic complications of impotence involve structural lesions in the testis as part of an overall defect in the pituitary‐testicular axis. In the present study testicular biopsies from ten oligospermic and/or impotent men with diabetes were evaluated by light and electron microscopy.

One biopsy was judged normal. The remaining tissue showed variable testicular pathology ranging from minimally to grossly affected. Seminiferous tubules had decreased tubule diameters, hyalinized tubule walls, and occluded lumina owing either to epithelial encroachment or cellular debris and exfoliated round germ cells. Sertoli cells were vacuolated and showed a high degree of apical cell membrane redundancy and degeneration. Although Sertoli‐Sertoli cell junctional complexes appeared normal, Sertoli junctional specializations associated with spermatids were structurally abnormal or absent. All tubules were variably depleted of adluminal compartment germ cell types. The interstitial compartment was filled with a collagen‐rich extracellular matrix concentrated around small blood vessels and seminiferous tubule walls. Capillaries and lymphatic endothelia appeared structurally abnormal and compromised by the interstitial “matrix expansion.” Some Leydig cells contained a variable number of small to large lipid droplets, vacuoles, and secondary lysosomes.

Results indicate the presence of tissue pathology in testes of impotent diabetic men. Discrete ultrastructural lesions in apical Sertoli cell cytoplasm are associated with spermatogenic disruption and morphological changes in the interstitial compartment suggest microvascular complications.
Histopathologic changes of uterus following gossypol treatment during early pregnancy in rats
Authors: Rikihisa Yasuko , Lin Young C. , Walton Amelia
Published: February 2005

Intramuscular injections of gossypol acetic acid (25 mg in 10% EtOH/kg/day beginning on day 2 of diestrus) disrupted early pregnancy in rats as determined by light and electron microscopy. As in pregnant controls, in the uteri of treated rats increased glandular secretion, stromal hyperemia, and decidual tissue formation were noted at days 3–5 of pregnancy. At day 6, extreme hyperemia and stromal hemorrhage had occurred around well‐developed decidual tissue with foci of denuded mucosal surface. There was extravasation of blood into the uterine lumen, which was absent in controls. At days 5 and 6 of pregnancy, electron microscopy revealed shorter and fewer microvilli on the uterine glandular cells in the treated versus the control uterus. Luminal epithelial cells had not undergone the normal changes of pregnancy. These results imply that gossypol administered under our conditions neither prevented nor delayed implantation and formation of decidual tissue in the rat uterine endometrium but continuing development of the endometrium was disrupted at day 6 of pregnancy. This disruption of pregnancy may have resulted from a luteolytic action by gossypol that would not permit full structural differentiation in the rat uterus after implantation.
Nonrandom positioning of Golgi apparatus in pancreatic B cells
Authors: Lucocq John , Montesano Roberto
Published: February 2005

The Golgi apparatus has a polarized distribution in a variety of cell types, and in certain epithelia its intracellular position correlates with the direction of vectorial transport and release of secretory products. We have studied quantitatively the orientation of the Golgi apparatus in pancreatic islet B cells by examining its location with respect to the juxtacapillary face of the cell. This was done (a) at the light microscope level on semithin sections of osmium‐impregnated islets, and (b) at the ultrastructural level on thin sections of intact pancreas. The data obtained with both methods show that in pancreatic B cells the Golgi apparatus is preferentially located in the position opposite to the juxtacapillary face of the cell. These results suggest a structural polarization of B cells, which may be important for the coordinate function of islets of Langerhans.
Activation of osteoclasts and the repopulation of bone surfaces following hibernation in the bat, Myotis lucifugus
Authors: Doty Stephen B. , Nunez Eladio A.
Published: February 2005

In previous studies of the adult bat, Myotis lucifugus, bone loss that occurred during the hibernating period was attributed to osteocytic osteolysis, rather than osteoclastic activity. We have used histochemistry and light and electron microscopy to determine the functional state of the skeleton during the hibernating period. We find that during hibernation the marrow cavity of the long bones is filled with lipid deposits interspersed with vascular sinusoids containing mononuclear cells and red blood cells. The lipid deposits are found within fat cells and at extracellular sites. Hematopoietic cells are absent, osteoclasts are absent, and the bone surfaces are covered with quiescent bone‐lining cells. Osteocytes retain their structural integrity and maintain canalicular systems with the bone lining cells and with other osteocytes.

During the arousal period, osteoclasts reappear on the bone surface, followed in time by increased numbers of osteoblast‐like cells. Perivascular cells undergo structural hypertrophy. Many mononuclear cells are now found in extravascular sites. The lipid content in the marrow is gradually reduced and replaced by hematopoietic cells. Each of these events occurs in a repeatable sequence that is related to the state of hibernation of Myotis lucifugus.
Use of the fluorochrome propidium lodide for the identification of Xenopus germ plasm during immunofluorescence studies
Authors: Smith R. C. , Neff A. W.
Published: February 2005

Addition of 0.5 μg/ml of the red fluorescent dye propidium iodide to the penultimate wash of Xenopus early embryo serial sections during immunofluorescence studies causes germ plasm to fluoresce brightly. Germ plasm can be accurately and speedily identified in the serial sections. The use of this dye is a marked improvement over previous methods of germ plasm identification in unstained sections. Studies involving screening for germ‐plasm‐specific antibodies are greatly facilitated by staining germ plasm red with propidium iodide and searching for green colabelling by fluoresceinated antibodies.
Tetralogy of fallot produced in chick embryos by mechanical interference with cardiogenesis
Authors: Aranega A. , Egea Jose , Alvarez L. , Arteaga M.
Published: February 2005

The tetralogy of Fallot was produced experimentally in the chick embryo by altering the development of the conus and delaying the disappearance of the conoventricular groove. The experimental procedure used consisted of placing a ligature or cerclage around the proximal portion of the conus for 24 hr in embryos in Hamburger‐Hamilton stages 17–21, thus altering cardiac hemodynamics particularly in the clonal region. At the same time the conus was prevented from aquiring its normal position owing to the persistence of the conoventricular groove. As a result, the most frequently observed abnormality (50%) was a complex of anomalies similar to tetralogy of Fallot in man. Varying degrees of pulmonary stenosis were observed in 85% of the experimental cases either as the only defect or in association with other cardiac malformations.
The effect of streptozotocin on the secretory activity of ameloblasts in rat incisor as revealed by radioautography after 3H‐proline administration
Authors: Karim A. C. , Pylypas S. P.
Published: February 2005

The effect of a diabetogenic dose of streptozotocin on the secretory activity of ameloblasts was investigated in the rat incisor by radioautography. One group of male Sprague‐Dawley rats was injected intravenously with streptozotocin in citrate buffer (pH 4.5). One hour later, this group was again injected intravenously with 3H‐proline (2 mCi/kg). A control group of animals was injected with 3H‐proline only. All the animals were sacrificed in groups of three at 5 min, 1 h, 2 h, 4 h and 8 h after 3H‐proline injection by perfusion with 3% phosphate‐buffered formaldehyde followed by an additional perfusion with 2.5% phosphate‐buffered glutaraldehyde. The incisors were extracted with the jaws, demineralized, and prepared for radioautographic observations and analysis. The principal effects of streptozotocin were as follows: There was an inhibition of 3H‐proline incorporation into the secretory ameloblasts at 5 min after injection. This was followed by a larger uptake and a slower passage of the label out of the cells into the enamel matrix than that seen in the control sample. Finally, there was a slower secretion of labeled proteins out of Tomes' processes between 1 and 4 h after injection.

Therefore, streptozotocin had a temporary inhibitory effect on the incorporation and secretion of 3H‐proline by the secretory ameloblasts of the rat incisor. This effect was present for about 4 h and was completely reversed 9 h after streptozotocin injection.
The accessory nerve nucleus in the baboon
Authors: Augustine James R. , White James F.
Published: February 2005

In the savanna baboon, Papio cynocephalus, the accessory nerve nucleus was identified by using a mixture of 20% free horseradish peroxidase (HRP) and 2.5% HRP conjugated to wheat germ agglutinin (WGA) in a 5% aqueous detergent solution (Nonidet P‐40). Following surgical exposure of the appropriate nerve branch to the sternocleidomastoid or trapezius muscle, the nerve was transected, placed in an Argyle tubing collar, and bathed in 5–10 μl of the tracer. After a 48‐hour survival time and vascular perfusion‐fixation, 40‐μm sections of the lower medulla oblongata and the cervical spinal cord were treated according to the tetramethyl benzidine (TMB)‐HRP method of Mesulam (J. Histochem. Cytochem. 26:106–117, 1978). The accessory nucleus extends as a distinct column of neurons from lower medullary levels into the rostral part of C5. One to ten labeled cells were present in each section, and all labeled neurons were located on the side of the bathed nerve. The rostral portion of the accessory nucleus occupies a central position, its intermediate portion occupies a lateral position, and its caudal portion occupies a central position within the ventral horn. All labeled neurons were confined to Rexed's lamina IX, ranged from 15 to 75 μm in diameter, and were either distinctly round (oval) or stellate in shape. Neurons within the baboon accessory nucleus supplying the sternocleidomastoid muscle were located from lower medullary to upper C2 spinal cord levels, while those supplying the trapezius muscle extended from C2 to C5.
Morphology of norepinephrine‐induced acute renal failure in the dog
Authors: Bulger Ruth Ellen , Burke Thomas J. , Cronin Robert E. , Schrier Robert W. , Dobyan Dennis C.
Published: February 2005

The 40‐minute infusion of norepinephrine (NE) into the renal artery of dogs produces a reversible ischemic model of acute renal failure. While the physiology of this model has been extensively studied, no complete description of the pathology exists. This study uses light microscopy and transmission electron microscopy to describe and quantitate the structural and ultrastructural changes which occur in the kidneys of dogs 1, 3, and 24 hours after the intrarenal infusion of 0.75 mg/kg/minute of NE. One hour after a 40‐minute NE infusion the majority of convoluted and straight proximal tubules showed apical blebs, loss of brush border, microvillar whorl formation, and mitochondrial condensation and high‐amplitude swelling with flocculent densities. Necrotic cells were occasionally seen at 1 hour. The injury was progressive after 3 hours and by 24 hours animals had either complete or partial patchy necrosis of all regions of the proximal tubule. The percentages of injured and necrotic proximal tubules in outer, mid‐, and inner cortical regions are presented. We conclude that the extent and pattern of injury seen after NE infusion differs significantly from the renal artery clamping model of ischemia.
Denervation‐induced changes in cell proliferation in the rat molar after wounding
Authors: Chiego Daniel J. , Klein Robert M. , Avery James K. , Gruhl Iris M.
Published: February 2005

The dental pulp has the capacity to initiate and maintain repair after trauma. The purpose of the present study was to quantitatively analyze the role of the peripheral nervous system in regulation of pulpal cell proliferation in response to wounding. Six groups often rats were used in these studies. There was one baseline group (wounded, but innervation intact) and five resection groups. The resection groups included rats with unilateral superior cervical ganglionectomy (SCG), unilateral inferior alveolar nerve resection (IAN), unilateral chorda tympani (CT) resection, IAN + SCG, or a complete unilateral nerve resection (IAN + SCG + CT). One millimeter of enamel and dentin was removed from the first mandibular molar on the experimental (resected) side. Therefore, each rat had an experimental and control molar. Rats were killed at various intervals from day 0 to day 15 after wounding and received 0.5 μCi/g b.wt. 3H‐thymidine 1 hour before death. For the baseline (innervation intact) data a peak in 3H‐thymidine incorporation occurred at 5 days after wounding. In the resected groups, there was a general increase in the number of labeled cells at the zero time point, and a suppression of the 5‐day peak with a delay in the proliferative response to wounding. The SCG + IAN‐resected group maintained the lowest number of labeled cells throughout the entire experimental period compared to the experimental baseline data and the two controls. At the initial and termination points the SCG + IAN‐resected groups demonstrated the highest number of labeled cells. The baseline data indicate that the maximal response to wounding occurs at day 5. Denervation results in a delay of the cell proliferative response to wounding with the most dramatic delay occurring in the IAN + SCG‐resection group. The results indicate that the autonomic and sensory components of the peripheral nervous system may interact in regulating the proliferative response of pulpal cells to wounding.
The structure of the atrioventricular conducting system in the avian heart
Authors: Szabóa Erno , Virágh Szabolcs , Challice Cyril E.
Published: February 2005

The atrioventricular conduction system in three avian species has been studied by light and electron microscopy. A morphologically definable atrioventricular node was not found in any of these. The atrioventricular bundle is a well‐defined structure, the proximal portion of which is in direct continuity with the atrioventricular ring, located in the arterial sheet of the muscular valve of the right atrioventricular opening. In the zone of transition between atrioventricular ring and bundle the compactness of the bundle is loosened, but the fibers do not establish continuity with the atrial fibers. The ring consists of Purkinje‐like fibers, 10–15 μm in diameter, and (peripherally) small 3–5‐μm‐diameter junctional fibers which are in continuity with the common atrial fibers. In the muscular atrioventricular valve the fibers of the ring are insulated from the ventricular myocardium by a connective tissue sheet of the annulus fibrosus. It is suggested that in the avian heart the atrioventricular ring may fulfill a role similar to that of the atrioventricular node of mammals.
Orthogonal arrays of particles in the gastric parietal cell of the rat: Differences between superficial and basal cells in the gland and after pentagastrin or metiamide treatment
Authors: Bordi Cesare , Amherdt Mylègne , Perrelet Alain
Published: February 2005

The basolateral plasma membrane of gastric parietal cells is characterized by the presence of orthogonal arrays of particles revealed by the freeze‐fracture technique. These arrays were quantitatively assessed in freeze‐fracture replicas of the gastric mucosa at two different levels of the gastric gland and after pentagastrin and metiamide treatment. The arrays were small and scarce in parietal cells located in the upper part of the gland, while they were markedly more abundant in parietal cells situated at the base of the gland. In both superficial and basal cells, the concentration of the arrays was significantly decreased after pentagastrin or metiamide treatment. This decrease was not due to an increase in the surface area of the basal plasma membrane. These results indicate that the concentration of the orthogonal arrays is a distinctive feature between superficial and basal parietal cells and that the arrays can be modulated by parietal cell function.
Effects of 30% intestinal resection on whole population cell kinetics of mouse intestinal epithelium
Authors: Cheng Hazel , McCulloch Christopher , Bjerknes Matthew
Published: February 2005

The intestine remaining after resection undergoes a well known compensatory response. Crypts and villi grow in size, and the number of proliferating cells in a crypt increases. The crypt labeling index, however, is unchanged, which is thought to suggest that the growth fraction also remains unchanged and hence that the system is enlarged, but otherwise the new steady‐state is similar to that of the controls. It is also generally accepted that no new crypts or villi are added to the adapting bowel. In this study we applied recently developed tools to study the response of the intestinal epithelium as a whole. Thus, the effects of 30% intestinal resection on whole population cell kinetics were determined by using flow cytometry, Coulter particle counting, and simple morphometric techniques.

In addition to the classic response, we found an increase in the rate of crypt production, which was due mainly to a shorter crypt replication cycle. Thus, new crypts were produced at a faster rate in the resected animals than in the transected controls. This resulted in an expansion of the crypt cell population in the epithelium folllowing resection. There was a corresponding expansion of the cycling cell population and thus an increase in the growth fraction of the resected epithelium. We conclude that for the crypt population, the classic story is correct with the exception that new crypts are added to the epithelium after resection. However, for the epithelium as a whole, the classic story is misleading as there appears to be an increase in the growth fraction of the epithelium after intestinal resection.
Telencephalic microvessels of premature beagle pups
Authors: Leuschen M. Patricia , Nelson Robert M.
Published: February 2005

The ultrastructural morphologic and morphometric characteristics of the telencephalic microvasculature of both germinal matrix and border‐zone cerebral cortex are analyzed from premature beagle puppies delivered by caesarean section in order to determine whether differences in the matrical vessels could account for their susceptibility to intraventricular hemorrhage. The germinal matrix microvessels are immature, since they contain intraluminal microvilli and junctional complexes (primarily tight junctions) that are not continuous between the lateral endothelial cell walls. The number of junctional complexes per vessel crosssection is less than either cortical vessels from the same premature animals or tissue from either site in full‐term animals. Morphometric data on the cross‐sectional area of vessels from the two sites indicate that the germinal matrix vessels have a significantly larger cross‐sectional area than the cortical vessels. The increase is due almost exclusively to a larger endothelial cell area per cross section. This pattern is an altogether different one from that seen in the term animals. There the germinal matrix vessels exhibit a steadily decreasing luminal area from birth through 72 hr, whereas endothelial cell cross‐sectional area is static. Here the luminal cross‐sectional area is smaller, but both endothelial cell and total vessel cross‐sectional areas are significantly larger. Structural components of the blood‐brain barrier undergo active modifications during the late prenatal period that are distinct from the modifications during the immediate postnatal period.
Remodeling of bone and bones: Effects of altered mechanical stress on the regeneration of transplanted bones
Authors: Storey Elsdon , Feik Sophie A.
Published: February 2005

We divided 116 rats weighing 50 gm into four groups with tails either left in situ or transplanted as follows: (1) straight in situ: untreated controls; (2) bent in situ: five caudal vertebrae (CV) in the loop; (3) straight transplants: three CV skinned and transplanted autologously; and (4) bent transplants: five CV skinned, bent to form a loop, and transplanted autologously. Tails were radiographed weekly up to 6 weeks and at 12 weeks, and microradiographic and histological studies were undertaken on selected specimens. At 12 weeks the bones in the apex of the loop of tails left in situ appeared bent with a straight‐to‐convex shaft on the outer side and a thicker, more concave one on the inner side. In the transplanted bent segments the bone shaft died and initially the reverse occurred: the outer shaft thickened and the inner resorbed completely. A new concave inner diaphysis then formed so that the bones in both instances were essentially similar in final shape. In the bent transplants the surviving osteogenic tissues regenerated and, adapting to the altered forces, formed a new bone shaft. This involved a change in the direction, amount, and nature of endochondral, periosteal, and regenerative growth and subsequent remodeling of bone. The results support previous observations that, within limits, the strain in the osteogenic envelope is an important factor in adaptation of bones to changing stress and that, where the envelope is deficient, the surviving tissues have the capacity to regenerate and repair defects in the bone so that it best resists the changing stresses applied to it.
Three‐dimensional reconstruction of vesicles in endothelium of blood‐brain barrier versus highly permeable microvessels
Authors: Coomber B. L. , Stewart P. A.
Published: February 2005

In this study the three‐dimensional organization of pinocytotic vesicles in mouse endothelia from permeable (choroid plexus, area postrema, and skeletal muscle) and blood‐brain barrier (bbb) (cerebral gray and white matter) microvessels was examined. Reconstructions of 75 segments of endothelial cells from microvessels were done with very thin (<23 nm) serial sections and tracings. A total of 2,013 vesicles from five tissues were reconstructed for this study. Vesicles were classified as to whether they were attached to other vesicles (fused), connected to golgi or endoplasmic peticulum (tubule‐connected), open to vessel lumen or ablumen (surface‐connected) or isolated in the cytoplasm (free).

The densities of tubule‐connected vesicles and free vesicles were the same in all four types of vessels. It seems unlikely, therefore, that these vesicles are related to vascular permeability. Vesicular clusters and surface‐connected vesicles were found in much higher densities in area postrema, choroid plexus, and skeletal muscle vessels than in bbb vessels. Single‐vesicle transendothelial channels were found in attenuated endothelia of area postrema and choroid plexus. These results support the hypothesis that endothelial vesicles play a role in vascular permeability, possibility by transient fusion of vesicle clusters to the plasmalemma, to form transendothelial channels.
Abnormalities of smooth muscle, basal laminae, and nerves in the aganglionic segments of the bowel of lethal spotted mutant mice
Authors: Tennyson Virginia M. , Pham Tuan Duc , Rothman Taube P. , Gershon Michael D.
Published: February 2005

The terminal portion of the bowel of the lethal spotted mutant mouse (ls/ls) lacks an enteric nervous system due to the failure of neural crest precursors to colonize this region during embryonic life. As a result, the mouse develops congenital megacolon. We have postulated that the defect occurs because the microenvironment of the aganglionic segment is segmentally abnormal and does not permit the migration and/or survival of the enteric neural or glial precursors in the affected zone. We have examined the terminal segment of adult ls/ls and control mice by light and electron microscopy to determine if the defect is associated with identifiable structural abnormalities that persist to maturity. A striking abnormality is an overgrowth of the muscularis mucosa in the adult ls/ls mouse, particularly in the outer longitudinal layer. Electron microscopy also reveals an extensive thickening of the basal lamina around smooth muscle cells. In addition, nerves that are derived from fibers that are extrinsic to this area are abnormal. Large bundles of nerve fibers, some of which contain myelinated axons, large‐caliber unmyelinated axons, and abundant collagen, are prominent in the intermuscular region of the aganglionic segments and often reach into the submucosa. The supporting cells of the unmyelinated and myelinated nerves in the aganglionic segment have voluminous perineural cytoplasm typical of immature Schwann cells. They also exhibit intermediate filaments in their cytoplasm. Otherwise they have the typical morphology of peripheral Schwann cells, rather than enteric glia, including individual ensheathment of axons and a surrounding basal lamina. We suggest that the extracellular matrix and/or cells of mesenchymal origin of the terminal bowel of the ls/ls mouse may prevent the ingrowth of the normal precursors of the glia as well as neurons of the enteric nervous system, but may permit or even encourage the ingrowth of abnormal numbers of extrinsic axons.
Effect of 16, 16‐dimethyl prostaglandin E2 methyl ester on weanling rat skeleton: Daily and systemic administration
Authors: Furuta Yoshihisa , Jee Webster S. S.
Published: February 2005

The effects of 0, 0.3, 1.0, and 3.0 mg of 16,16‐dimethyl prostaglandin E2 methyl ester (Di‐M‐PGE2) per kilogram per day administered subcutaneously for 21 days to fluorescent‐labeled weanling rats were studied, by single‐photon absorptiometric and static and dynamic histomorphometric techniques, to determine possible alterations in growth and mineralized tissue mass and their mechanisms of response. Specimens of femurs, proximal tibia, and tibial shaft were analyzed. Di‐M‐PGE2 caused a reduction in bone elongation and a dramatic accumulation in metaphyseal trabecular hard tissue mass. At high doses, the growth cartilage exhibited reduced thickness and degenerative cell size and cell production rate. The increased metaphyseal trabecular hard tissue mass was restricted to the secondary spongiosa region and was observed at all dose levels. The metaphysis was further characterized by an increase in bone and calcified cartilage cores, a marked elevation in osteoblast and osteoclast numbers, in osteoblast‐to‐osteoclast ratios, and in ratios of differentiated cells to osteoprogenitor cells. These findings were consistent with the interpretations that Di‐M‐PGE2 (1) depressed bone elongation by delaying the division and maturation of growth plate chondrocytes; (2) stimulated the differentiation of osteoblasts and osteoclasts, thus generating more differentiated bone cells but suppressing their activities; and (3) incresed metaphyseal trabecular hard tissue by creating an imbalance in osteoblasts over osteoclasts and suppressing hard tissue resorption.
Effect of controlled dietary consistency and cage environment on the rat mandibular growth
Authors: McFadden L. R. , McFadden K. D. , Precious D. S.
Published: February 2005

Forty Fischer strain inbred albino rats, evenly divided by sex, were obtained at 9 days of age. The animals were weaned at 21 days and randomly divided into the four experimental groups. Two variations on dietary consistency, hard and soft diet, as well as two variations on cage environment, normal and no biting surfaces, constituted the experimental groupings. The experimental period consisted of 16 weeks during which the animals were raised under the designated conditions. At the end of the experimental period the animals were killed with carbon dioxide, and the entire mandible, and both femurs, were dissected free. Weight and volumetric analysis were carried out in a standard fashion on the cleaned specimens. Area and linear measurements were performed and analyzed with a specially designed computer program. The results showed that there was sexual dimorphism in the Fischer rat both with respect to body weight and the weight, volume, area, and linear measurements of the mandible. The effects of dietary consistency had a greater influence on mandibular ramus size and form than did those caused by alteration in cage environment. The posterior region of the mandible, in association with the heavy muscles of mastication, was affected more by dietary consistency than was the anterior region. The entire region of the mandibular ramus acted as an area of adaptation and growth. The findings of this study indicate that dietary consistency has a small but significant effect on mandibular size in specific measurements. The cage environment used in this experiment did not limit function to the extent necessary to see measurable changes in mandibular measurements.
Crypt production in normal and diseased human colonic epithelium
Authors: Cheng Hazel , Bjerknes Matthew , Amar Jack , Gardiner Geoffrey
Published: February 2005

New crypts are added continously to the adult mouse intestinal epithelium by a process of crypt replication. Branching crypts found in the epithelium represent a stage in the process of crypt replication. In “normal” human colonic epithelium we found a small but definite percentage of branching crypts, 0.44 ± 0.16, indicating that new crypts are being produced at a low rate in this epithelium. Significantly higher (P < .001) percentages of branching crypts, 30.4 ± 5.75, 15.1 ± 1.08, and 13.2 ± 1.05, were found in diseased colonic epithelium from patients with ulcerative colitis, Crohn's disease, and multiple polyposis, respectively. These results may be interpreted as suggesting that the rate of crypt production in human colonic epithelium is increased in a number of disease states. We concluded that, as in the mouse intestinal epithelium, the rate of the crypt replication process in human colonic epithelium is plastic and may respond to a variety of conditions.
Carbohydrate cytochemistry of rhesus monkey tracheal submucosal glands
Authors: St. George Judith A. , Nishio Susan J. , Cranz Diane L. , Plopper Charles G.
Published: February 2005

This study was designed to characterize the ultrastructure and carbohydrate content of secretory cells in submucosal glands of rhesus monkey and to compare this information with that available for humans. The tracheas from five adult monkeys were fixed by airway infusion, processed, and embedded for both light and transmission electron microscopy. Histochemical stains including alcian blue–periodic acid–Schiff, dialyzed iron, and high‐iron diamine‐alcian blue were applied to serial glycol methacrylate sections. The cytochemical stains used included periodic acid‐thiocarbohydrazide–silver proteinate, high‐iron diamine, and low‐iron diamine. The glandular secretory cells were divided into four categories based on ultrastructure and location within the gland. Cells in the first category resembled the mucous cell of the surface epithelium and were located in ducts most proximal to the tracheal lumen. The second category consisted of cells that were located in distal ducts and contained large electron‐lucent granules. The granules in both of these cell groups contained material that was periodate‐reactive and sulfated. Cells of the third category contained granules that were either electron‐lucent or electron‐dense. These cells, which were difficult to characterize as either serous or mucous, were located in secretory tubules and acini and contained periodate‐reactive glyco‐conjugates that were either sulfated or nonsulfated. The last category consisted mainly of cells that contained electron‐dense granules that were lightly periodate‐reactive or a few that were unreactive with any of the cytochemical methods used here. We concluded from this study that 1) the submucosal glands of rhesus monkey contain secretory cells with a variety of morphologies; 2) the secretory cells, which in some cases are not easily identified as mucous or serous, contain material that is periodate‐reactive and sulfated, contain material that is periodate‐reactive only, or contain no carbohydrate as detected by the cytochemical methods used; and 3) the submucosal glands of rhesus monkey trachea resemble those described in human airways.
The Golgi complex of the early spermatid in guinea pig
Authors: Burgos M. H. , Gutiérrez L. S.
Published: February 2005

After aldehyde‐tannic fixation, Zinc‐iodine‐osmium fixation, Phospho Tungstic acid‐chromium stain and two cytochemical reactions, the ultrastructure of the Golgi complex of early spermatids in the guinea pig reveals two different regions. One, close to the cell surface, involves endoplasmic reticulum (ER), intermediate vesicles, and Golgi outer cisternae and has membranes of uniform thickness and symmetrical trilaminar pattern, a strong ZIO precipitate, and an almost negligible cytochemical reaction to polysaccharides and cholesterol. The other region, close to the nucleus, exhibits thicker, sometimes asymmetric membranes, a polygonal network coating the thick cisterna, condensing vacuoles and areas of the acrosomal membrane, an intense reaction to polysaccharides and cholesterol, and packages of different densities in the condensing vacuoles and acrosome. This work also shows the coincidence of the cytochemical marker of cholesterol with the polygonal coating of clathrin in the condensing face of the Golgi.
Scanning electron microscope study of the developing microvasculature in the postnatal rat lung
Authors: Caduff J. H. , Fischer L. C. , Burri P. H.
Published: February 2005

During postnatal growth the parenchymal septa of rat lung undergo an impressive restructuring. While immature septa are thick and contain two capillary layers, mature septa are slender and contain a single microvascular network. Using the Mercox® casting technique and scanning electron microscopy, we investigated the mode and the timing of the transformation of the pulmonary capillary bed. During the third postnatal week the parenchymal septa rapidly mature to match adult morphology. Even in adult lungs, however, remnants of the immature status are present: A capillary bilayer is regularly found at the base and the tip of the septa. Our observations support the concept that reduction of intervening tissue, partial fusion of the two capillary networks, and preferential growth lead to the mature vascular arrangement. The fact that true mature interalveolar septa show a denser capillary network than alveolar walls abutting onto pleura, bronchi, or larger vessels is consonant with the fusion theory. Towards the nonparenchyma, the capillary network surrounding every airspace had no counterpart to fuse with.

From quantitative data it can be calculated that owing to lung growth, mesh size should increase more than four times between birth and adult age. The adult lung network, however, is denser than the one in young animals. This means that new meshes must be added during growth. We propose that small holes observed in sheet‐like regions of the microvascuiature enlarge to form new capillary meshes. With this mechanism of in‐itself or intussusceptional growth, sprouting of individual capillary segments to increase network size is no longer needed.
Cell types in the pineal gland of the horse: An ultrastructural and immunocytochemical study
Authors: Cozzi Bruno
Published: February 2005

A combined ultrastructural and immunocytochemical study was performed on the pineal gland of the horse in order to identify the cell types present and describe their characteristics. Comparisons have been made with other mammals. Two main cell types are present: pinealocytes and glial cells. Pinealocytes display different degrees of electron density in the nucleus and the cytoplasm, yet no ultrastructural feature supports the idea of separate populations. Putative secretory materials are stored in vesicles related to the Golgi apparatus. A variety of electron‐dense bodies are present in the cytoplasm. Interstitial cells responding to anti‐GFAP (glial fibrillary acid protein) and anti‐vimentin antibodies, but not to anti‐neuronal 200‐kD protein antibodies, are located close to the perivascular spaces and connective septa. Morphological and immunocytochemical features support classifying them as astrocytes, probably protoplasmic. The presence of a cavity lined with pericytes, putatively a remnant of the embryonic lumen of the organ, is a consistent finding and may relate to the third ventricle.
Embryological development of human palmar, plantar, and digital flexion creases
Authors: Kimura Sumiko , Kitagawa Tadashi
Published: February 2005

The aim of this study is to document the prenatal stages of development of the flexion creases on the surfaces of the human palm, sole, and digits. We used 160 human fetuses, 6–20 weeks of gestational age, to observe the morphological features of the hand and foot, as well as the period and location of the appearance of the flexion creases. We found that most creases develop concurrently with the appearance of the fetal volar pads and the rest develop independently of them. Furthermore, with some exceptions, the creases seem to develop independently of the flexion movements of hand and foot.
Variation in human fungiform taste bud densities among regions and subjects
Authors: Miller Inglis J.
Published: February 2005

Taste sensitivity is known to vary among regions of the tongue and between subjects. The distribution of taste buds on the human tongue is examined in this report to determine if interregional and intersubject variation of taste bud density might account for some of the variation in human taste sensitivity. The subjects were ten males, aged 22–80 years, who died from acute trauma or an acute cardiovascular episode. Specimens were obtained as anatomical gifts or from autopsy. A sample of tissue about 1 cm2 was taken from the tongue tip and midlateral region; frozen sections were prepared for light microscopy; and serial sections were examined by light microscopy to count the taste buds. The average taste bud (tb) density on the tongue tip was 116 tb/cm2 with a range from 3.6 to 514 among subjects. The number of gustatory papillae on the tip averaged 24.5 papillae/cm2 with a range from 2.4 to 80. Taste bud density in the midregion averaged 25.2 tb/ cm2 (range: 0–85.9), and the mean number of gustatory papillae was 8.25/cm2 (range: 0–28). The mean number of taste buds per papilla was 3.8 ± 2.2 (s.d.) on the tip and 2.6 ± 1.5 (s.d.) on the midregion. Subjects with the highest taste bud densities on the tip also had the highest densities in the midregion and the highest number of taste buds per papilla. Taste bud density was 4.6 times higher on the tip than the midregion, which probably accounts for some of the regional difference in taste sensitivity. The difference of more than 2 log units in taste bud density probably accounts for some differences in taste sensitivity among human subjects.