bluuebunny/crossref_metadata_2025 huggingface dataset:
Venous valve anatomy and morphometry: Studies on the duckling using vascular corrosion casting
Authors: Hossler Fred E. , West Russell F.
Published: February 2005

The anatomy and morphometry of venous values associated with the vasculature of the head of the duckling were studied using vascular corrosion casting and scanning electron microscopy. All valves encountered were bicuspid, and casts typically exhibited slight expansions at valve sinuses and deep slits at the sites of valve leaflets. The locations, numbers, and orientations of endothelial nuclei on all surfaces of the valves were clearly revealed by imprints in the casting resin. Endothelial cell densities were significantly higher on the surfaces of valve leaflets (about 10 cells/ 1,000 /μm2) than on other venous surfaces (about 7 cells/ 1,000 μm2). Endothelial nuclei on the medial surface of the valve leaflet were oriented parallel to the long axis of the vessel, whereas those on the lateral surface were oriented perpendicular to that axis. The close proximities of valves in some vessels and the presence of anomalies such as the sharing of leaflets by adjacent valves were readily demonstrated with the corrosion‐casting techniques. These methods provide a useful means for studying the fine, three‐dimensional details of venous valve anatomy.
Trabecular, nasal, branchial, and pericardial cartilages in the sea lamprey, Petromyzon marinus: Fine structure and immunohistochemical detection of elastin
Authors: Wright Glenda M. , Armstrong Leslie A. , Jacques Anna M. , Youson John H.
Published: February 2005

Immunohistochemical and ultra‐structural methods were used to examine the distribution of elastin and the fine structure of the trabecular, nasal, branchial, and pericardial cartilages in the sea lamprey, Petromyzon marinus. The cells and matrix, as well as the overall organization of these components, in larval and adult trabecular cartilage resemble those of adult annular and piston cartilages (Wright and You‐son: Am. J. Anat, 107:59–70, 1983) Chondrocytes are similar to those in hyaline cartilage. Lamprin fibrils and matrix granules, but no collagen fibrils, are found in a matrix arranged into pericellular, territorial, and interterritorial zones. Branchial, pericardial, and nasal cartilages differ from trabecular, annular, and piston cartilages in the organization of their matrix and in the structural components of their matrix and perichondria. Furthermore, immunoreactive elastin‐like material is present within the perichondria and peripheral matrices of nasal, branchial, and pericardial cartilages in both larval and adult lampreys. Oxytalan, elaunin, and elastic‐like fibers are dispersed between collagen fibers in the perichondrium. The matrix contains lam‐prin fibrils, matrix granules, and a band of amorphous material, which is reminiscent of elastin, in the periphery bordering the perichondrium.

The presence of elastic‐like fibers and elastin‐like material within some lamprey cartilages implies that this protein may have evolved earlier in vertebrate history than has been previously suggested.
Mechanoreceptors in articular tissues
Authors: Zimny Marilyn L.
Published: February 2005

The morphology, distribution, and function of mechanoreceptors in joint capsules, ligaments, knee‐joint menisci, and articular disks of the temporomandibular joints of animals, including humans, have been reviewed. In addition to free nerve endings, three types of joint receptors are present in most animal joints: (1) a Ruffini‐like receptor situated in the capsule, (2) a Golgi tendon organ situated in a ligament; and (3) the encapsulated Pacinian‐like corpuscle. In the anterior cruciate ligament, nerve fibers enter from the subsynovial connective tissue and terminate in receptors. Most of the receptors are found in the distal portion of the ligament. In the meniscus, nerves penetrate the outer and middle one‐third of the body and the horns from the perimeniscal tissue, with a greater concentration at the horns. In the temporomandibular articular disk, the mechanoreceptor density is greatest at the periphery and progressively decreases toward the center. If a joint has an intra‐articular structure, mechanoreceptors undoubtedly are present within it. The concentration of mechanoreceptors appears greater in areas related to the extremes of movement and probably represents the first line of defense in sensing these extremes. These afferent discharges elicit support from discharging mechanoreceptors located in the joint capsule and subsequently from those in the surrounding muscles. This total afferent output alerts the central nervous system of impending injury, which can then be averted through reflex mechanisms.
Vascularization of the telencephalic choroid plexus of a ganoid fish [Acipenser ruthenus (L.)]
Authors: Weiger T. , Lametschwandtner A. , Kotrschal K. , Krautgartner W.‐D.
Published: February 2005

The vascularization of the telencephalic choroid plexus of the sterlet Acipenaer ruthenus, a ganoid fish, was examined by vascular corrosion casting and by light and transmission electron microscopy. The arterial supply is from the dorsal mesencephalic artery via: (1) the ventral choroidal arteries (left and right); (2) the dorsal choroidal arteries (left and right); (3) the caudal choroidal arteries (left and right; (4) the ventral arteries of the dorsal sac; and, from the olfactory arteries, via 5) the rostral choroidal arteries. The venous drainage is mainly through a single main choroidal vein that can take various courses either directly to the anterior cardinal vein or via the middle cerebral vein to the anterior cardinal vein. To a lesser extent, the plexus is drained via the lateral telencephalic veins and the ventral vein of the dorsal sac to the middle cerebral vein. By angioarchitecture and form, the plexus can be subdivided into five distinct parts: the surface network, the median folds, the large lateral folds, the small lateral folds, and the area common to the bottom of the dorsal sac and the telencephalic plexus. Diameters of terminal vessels as measured from vascular corrosion casts and from paraplast, semithin, and ultrathin sections were never less than 10 /xm. It is suggested that the different areas in one plexus may have different functions with respect to secretion and absorption of cerebrospinal fluid.
Ultrastructural study of the alveolar‐capillary membrane and the tubular endoplasmic reticulum in alveolar type I cells of the caprine lung
Authors: Atwal Onkar S.
Published: February 2005

The ultrastructural features of alveolar type I cells of the goat lung were studied by using vascular perfusion and direct airway instillation of fixatives. The morphological features of smooth endo‐plasmic reticulum (SER) were characterized by measuring the diameter of individual SER tubules which conformed in size and appearance to the tubular endoplasmic reticulum (TER) already described in various types of epithelium. The TER appeared as large tubular aggregates in a palisade arrangement; these aggregates ramified into various areas of the extended cytoplasm of alveolar type I cells. The TER also existed as a mixture of short cisternae and vesicles, and glyco‐gen alpha particles were present in the non‐perikar‐yonic portion of the cell. The different forms of TER had varying relationships to the plasmalemma. The interchangable configurations seen in the structure of TER indicated the functional modalities of the cells and were comparable to similar structural modifications in electrolyte‐secreting cells. The role of TER, microtubules, and large populations of endocytic vesicles in the alveolar type I cells in the goat lung is examined in the context of physiological eructation of rumenal gases and the absorption of electrolyte‐rich fluids which escape into the lung at each eructation in ruminants.
Ultrastructure of odontogenic cells during enameloid matrix synthesis in tooth buds from an elasmobranch, Raja erinacae
Authors: Prostak Kenneth S. , Skobe Ziedonis
Published: February 2005

The ultrastructure of the inner epithelial cells (IDE) and odontoblasts in elasmobranch (Raja erinacae) tooth buds was investigated by transmission electron microscopy to determine what contribution each cell type makes to the forming enameloid matrix.

Row II, early stage, IDE cells contained few organelles associated with protein synthesis, whereas preodontoblasts appeared competent to initiate extracellular matrix production. Row III IDE cells are also devoid of organelles related to secretory protein synthesis, although these IDE cells accumulated large pools of intracellular glycogen. The glycogen appeared to be packaged into vesicles and exocytosed into the lateral extracellular space toward the forming enameloid matrix.

Row III odontoblasts had a morphology consistent with an active protein secretory cell. No procollagen granules were present within the odontoblasts, however, nor were many collagen fibers observed in the enameloid matrix. Instead, non‐collagenous “giant” fibers having 17.5‐nm periodic cross striations were associated with the imaginations of odontoblast cell processes. Giant fibers, which spanned a clear zone adjacent to the odontoblasts, terminated within the enameloid matrix. Smaller 25‐nm‐wide “unit” fibers emanated from the giant fiber tips to form the bulk of the enameloid matrix. The clear zone, which separated the odontoblasts from the enameloid matrix at early stages, diminished in size at later stages until the odontoblast processes were completely embedded in the enameloid matrix. Nascent enameloid crystallites were observed only after a layer of unmineralized predentin was deposited beneath fully formed enameloid matrix.

The results suggest that the major constituent of the enameloid matrix in skates is a non‐collagenous protein derived from the odontoblasts. The inner dental epithelial cells appear to contribute large quantities of carbohydrates to the forming enameloid matrix.
Cellular stages in cartilage formation as revealed by morphometry, radioautography and type II collagen immunostaining of the mandibular condyle from weanling rats
Authors: Luder Hans U. , Leblond C. P. , von der Mark K.
Published: February 2005

The role played by cell addition, cell enlargement, and matrix deposition in the endochondral growth of the condyle was assessed in weanling rats by four approaches making use of the light microscope: morphometry, 3H‐thymidine radioautography, 3H‐proline radioautography, and immunostaining for the cartilage‐specific type II collagen.

From the articular surface down, the condyle may be divided into five layers made up of cells embedded in a matrix: (1) the articular layer composed of static cells in a matrix rich in fibers presumed to be of type I collagen, (2) the polymorphic cell layer including the progenitor cells from which arise the cells undergoing endochondral changes, (3) the flattened cell layer in which cells produce a precartilagenous matrix devoid of type II collagen while undergoing differentiation in two stages: a “chondroblast” stage and a short “flattened chondrocyte” stage when Intracellular type II collagen elaboration begins, (4) the upper hypertrophic cell layer, in which cells are “typical chondrocytes” that enlarge at a rapid rate, actively produce type II collagen, and deposit it into a cartilagenous matrix, and (5) the lower hypertrophic cell layer, composed of chondrocytes at a stage of terminal enlargement while the cartilagenous matrix is adapting for mineralization.

3H‐thymidine radioautographic results indicate that the turnover time of progenitor cells in the polymorphic cell layer is about 2.9 days. The time spent by cells at each stage of development is estimated to be 1.4 days as chondroblasts, 0.5 days as flattened chondrocytes, 2.3 days as the chondrocytes of the upper hypertrophic cell layer, and 1.1 days as those of the lower hypertrophic cell layer.

Calculations referring to a 1 × 1‐mm square‐sided column extending from the articular surface to the zone of vascular invasion provide the daily rate of cell addition (0.0077 mm3), extracellular matrix deposition (0.0127 mm3), and cell enlargement (0.0302 mm3). Hence the respective contribution of the three factors to condyle growth is in a ratio of about 1:1.6:4. This result emphasizes the role played by cell enlargement in the overall growth of the condyle.
Cytoarchitecture of muscle in a genetic model of murine diabetes
Authors: Feczko John D. , Klueber Kathleen M.
Published: February 2005

Although diabetic neuropathy is well documented, diabetic myopathy is not, except for descriptions of diabetic patients with muscular weakness thought to be due to metabolic changes in the muscle. Muscle and nerve are dependent on each other for normal structure and function; since the peripheral nerve is damaged in diabetes, one would expect concomitant changes in the muscle. This study examines the cytoarchitecture of diabetic muscle. The extensor digitorum longus (EDL) muscles from 165‐day‐old C57BL/KsJ db‐m mice were examined using electron microscopy. Morphological analysis of the diabetic EDL revealed that a significant number of the myofibers, examined within the midbelly region of the muscle, exhibited various degrees of degeneration, signs of denervation, and abnormal lipid stores. Both myoneural junctions and muscle spindles showed significant signs of degeneration, denervation, and abnormal structure. Thus the morphologic changes seen could account for the physiologic changes seen in diabetic muscle.
Glycoconjugate histochemistry of the rat fundic gland using Griffonia simplicifolia agglutinin‐II during the development
Authors: Ihida Kaori , Suganuma Tatsuo , Tsutama Shinichiro , Murata Fusayoshi
Published: February 2005

The development and maturation of fundic glands of Wistar rats were studied using Griffonia simplicifolia agglutinin‐II (GSA‐II) histochemistry at the light microscopic and electron microscopic levels.

In adult rats, mucous neck cells and cells intermediate between mucous neck cells and chief cells were specifically labeled with GSA‐II, whereas other fundic gland cells were virtually negative.

Ontogenetic studies revealed that GSA‐II positive cells appeared at the bottom of the gland by 21 days of gestation. With differentiation and aging, the elongation of the fundic gland continued, and the labeling intensity of the mucous neck cells increased by 3 weeks after birth. Cells intermediate between mucous neck cells and chief cells were discernible from 3 days after birth. Typical mucous neck cells appeared at 3 weeks after birth, when their labeling intensity with colloidal gold (CG) particles approximated that of adults. On the other hand, the reactive cell population gradually moved from the bottom toward the middle portion of the gland. Finally, the reactive cells were localized at the neck portion of the fundic gland.

These results suggest that GSA‐II is a valuable marker for studying mucous neck cells and both their precursor cells and their derivatives.
Neural and vascular provisions of rat interscapular brown adipose tissue
Authors: Nnodim Joseph O. , Lever Jeffrey D.
Published: February 2005

The innervation of rat interscapular brown adipose tissue has been studied by light and fluorescence microscopy and electron microscopy after treatment with “false” adrenergic neurotransmitters 5‐ and 6‐hydroxydopamine. The vascular markers neoprene latex and thioflavin S were used to define the blood vascular arrangements within and around the tissue.

Catecholaminergic innervation was revealed by fluorescence microscopy at both parenchymal and vasomotor sites. In animals injected with 6‐hydroxydopamine, this catecholaminergic fluorescence was extinguished in the parenchymal nerve distribution and markedly reduced in the vasomotor plexus.

Identification of an extensive network of noradrenergic vasomotor and parenchymal nerve terminals was established by electron microscopy after 5‐ and 6‐hydroxydopamine administration, but unmarked terminals were also observed in both distributions. These unmarked terminals might represent an additional nonnoradrenergic nerve supply to interscapular brown adipose tissue.

The thoracodorsal veins draining the fat pads are directly tributary to a large median perforating vein, which joins the azygos vein, and are also continuous with the axillary vein. In addition to the recognized vascular distribution pattern of lobular arteries supplying an abundant capillary plexus drained by lobular veins, direct arteriovenous anastomoses were observed within the interscapular brown fat pad. It is postulated that these additional vascular arrangements are determinant in the phenomenal increase in blood flow through brown adipose tissue during metabolic stimulation.
Distribution of microspheres in plantaris muscles of resting and exercising rats as a function of fiber type
Authors: Ong T. C. , Hayes D. A. , Armstrong R. B.
Published: February 2005

The purpose of this study was to determine histologically the distribution of microspheres (MSs) (14 μm), and hence the relative distribution of blood flow, in rat plantaris muscle relative to the fiber types (fast‐twitch‐oxidative‐glycolytic [FOG], fast‐twitch‐glycolytic [FG], and slow‐twitch‐oxidative [SO]). Three conditions were investigated: (1) preexercise standing; (2) treadmill locomotion at 15 m/min (fast walking); and (3) treadmill locomotion at 60 m/min (moderate galloping). The MS suspension (containing 1 × 106 MSs) was infused into the ascending aorta via a catheter in the carotid artery under each of the 3 conditions so that MSs were distributed to the tissues in proportion to their respective blood flows. Sections (20 m̈m) of the plantaris muscle were cut and assayed for reduced nicotinamide adenine dinucleotide tetrazolium reductase (NADH‐TR) and myofibrillar adenosine triphosphatase (ATPase) activities so the fibers could be typed as SO, FOG, or FG. MSs were located in the NADH‐TR sections, and the fibers next to the MSs were classified and counted. The observed numbers of fibers of each type in each condition that were adjacent to MSs were compared to the predicted number of adjacent fibers based on the assumption the MSs were randomly distributed in the tissue. This analysis demonstrated that MSs (and blood flows) were preferentially distributed to SO fibers during preexercise, to SO and FOG fibers during slow locomotion, and to FOG fibers during fast locomotion. The data support the contention that blood flow is distributed in muscles of conscious animals as functions of fiber type and exercise intensity.
Primary olfactory projections and the nervus terminalis in the African lungfish: Implications for the phylogeny of cranial nerves
Authors: von Bartheld Christopher S. , Claas Barbara , Münz Heinrich , Meyer Dietrich L.
Published: February 2005

Primary olfactory and central projections of the nervus terminalis were investigated by injections of horseradish peroxidase into the olfactory epithelium in the African lungfish. In addition, gonadotropin‐releasing hormone (GnRH) immunoreactivity of the nervus terminalis system was investigated. The primary olfactory projections are restricted to the olfactory bulb located at the rostral pole of the telencephalon; they do not extend into caudal parts of the telencephalon. A vomeronasal nerve and an accessory olfactory bulb could not be identified. The nervus terminalis courses through the dorsomedial telencephalon. Major targets include the nucleus of the anterior commissure and the nucleus praeopticus pars superior. Some fibers cross to the contralateral side. A few fibers reach the diencephalon and mesencephalon. No label is present in the “posterior root of the nervus terminalis” (=“Pinkus's nerve” or “nervus praeopticus”). GnRH immunoreactivity is lacking in the “anterior root of the nervus terminalis”, whereas it is abundant in nervus praeopticus (Pinkus's nerve). These findings may suggest that the nervus terminalis system originally consisted of two distinct cranial nerves, which have fused–in evolution–in most vertebrates. Theories of cranial nerve phylogeny are discussed in the light of the assumed “binerval origin” of the nervus terminalis system.
Lesions in the rat soleus muscle following eccentrically biased exercise
Authors: Ogilvie Robert W. , Armstrong Robert B. , Baird Kenneth E. , Bottoms Charles L.
Published: February 2005

Morphological changes in skeletal muscle related to lenghening (eccentric) contractions have been noted by several laboratories. However, a systematic examination of skeletal muscle following repetitive ecentric ontractions is lacking. This study was undertaken to study lesions and determine their relative densities in rat soleus muscle 30 min following level or downhill treadmill exercise. Following fixation in situ by vascular perfusion, toluidine‐blue‐stained 1‐μm sections of the muscle samples selected at 73‐μm intervals were scanned with a light microscope. Three types of lesions were noted: focal disruptions in the A‐band, localized dissolution of Z‐lines, and clotting of muscle fibers. Soleus muscle from the caged controls and the tibialis anterior muscle from downhill‐exercised rats were essentially free of lesions. Eighty‐nine percent of the soleus m. lesions in the downhill runner group and 97% of those in the level runner group were A‐band disruptions. A‐band lesion density was significantly higher in the soleus muscle of the downhill runners compared to level runners with the highest incidence in the distal half. A‐band lesion density was lower in soleus muscles from level runners; however, the highest intramuscular incidence was in the proximal rather than the distal end. The results indicate that a disruption of the A‐band is a principal change within some skeletal muscle fibers 30 min following repetitive eccentric contractions.
Phosphoprotein synthesis and secretion by odontoblasts in rat incisors as revealed by electron microscopic radioautography
Authors: Inage Toshihlko , Toda Yoshihlsa
Published: February 2005

The secretory pathway of clentin phosphoproteins in rat incisors was studied by electron microscopic radioautography after the injectionof 3H serine, and the results were compared with those using 3H‐proline as a tracer.

Five min after injection of 3H‐serine, radioactivity was found in the rough endoplasmic reticulum. At 10 min, silver grains were observed over the spherical portions of the cisface of the Golgi apparatus. At 20 min after injection, silver grains were seen over the cylindrical portions of the transface of the Golgi apparatus. The secretory granules showed the strongest reaction from 20 min to 1 hr. At 45 min, a significant labeled band appeared at the mineralization front. At 1 hr, the labeling at the mineralization front began to appear in the mineralized dentin, and after 12 hr this labeled band was located within the mineralized dentin.

The pathway of 3H‐proline was essentially the, same The pathway of H‐proline movedmrore slowly as that of 3H‐serine, 3H‐proline than 3H‐serine, especially in transit from the rough endoplasmic reticulum to the Golgi apparatus. Secretory granules were heavily labeled from 30 min to 1 hr after injection of 3H‐proline; no labeling was found at the mineralization front at 45 min. The labeling seen initially over the predentin was over the mineralized dentin no earlier than 6 hr after injection.

The labeling pattern with 3H‐serine is closely related to the localization of phosphoproteins, whereas the pattern with 3H‐proline reflects the production of collagen rather than of phosphoproteins. The present radioautographic results indicate that dentin phosphoproteins are related to secretory granules and are secreted by Odontoblasts at the mineralization front and also that phosphoproteins are involved in the process of mineralization of the circumpulpal dentin.
Bone cell biology: The regulation of development, structure, and function in the skeleton
Authors: Marks Sandy C. , Popoff Steven N.
Published: February 2005

Bone cells compose a population of cells of heterogeneous origin but restricted function with respect to matrix formation, mineralization, and resorption. The local, mesenchymal origin of the cells which form the skeleton contrasts with their extraskeletal, hemopoietic relatives under which bone resorption takes place. However, the functions of these two diverse populations are remarkably related and interdependent. Hone cell regulation, presently in its infancy, is a complicated cascade involving a plethora of local and systemic factors, including some components of the skeletal matrices and other organ systems. Thus, any understanding of bone cell regulation is a key ingredient in understanding not only the development, maintenance, and repair of the skeleton but also the prevention and treatment of skeletal disorders.
Prenatal and postnatal development of the small intestine in the insectivore Suncus murinus
Authors: Kiso Yasuo , Oku Kazuomi , Yamauchi Shoji
Published: February 2005

The development of the small intestine in the insectivore Suncus murinus was noted during the period from 21 days' gestation to 20 clays after birth. At 21 days of gestation, the proximal small intestine exhibited the beginning of villus formation, whereas the distal small intestine preserved the stratified epithelium. Stratified epithelium in the distal small intestine changed into a single layer by 24 days' gestation. At 26 day's gestation, each epithelial cell was immature; but by 28 days mature‐looking epithelial colls were found. The shape of the villi changed from cuboid to columnar during the same period. The connective‐tissue cores of the villi began to develop at 7 days after birth in the proximal small intestine and at 15 days after birth in the distal small intestine. Crypts appeared at 15 days after birth.

Endocytosis of epithelial cells took place at 28 days of gestation. In the proximal small intestine, supranuclear vesicle clusters were observed first at birth; they began to decrease both in number and size at 10 days' gestation and then disappeared completely by 20 days after birth. In the distal small intestine, large supra‐nuclear vacuoles were observed first at 28 days of gestation. Although these vacuoles invariably were found up to 15 days after birth, they also disappeared completely by 20 days. Epithelial cells showed a structure similar to those of the adult after weaning.
Formation of secretion granules in the Golgi apparatus of pancreatic acinar cells of the rat
Authors: Rambourg A. , Clermont Y. , Hermo L.
Published: February 2005

The three‐dimensional structure of the Golgi apparatus and its components has been analyzed in sections of pancreatic acinar cells by using stereopairs of electron microscope photographs. Pancreatic tissue fixed in glutaraldehyde was postfixed in reduced osmium, and the sections were stained with lead citrate. Tissues were also treated to demonstrate phosphatase activity (i.e., nicotinamide adenine dinucleotide phosphatase, NADPase; thiarnine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase). The following stacked components were observed along the branching, anastomotic, continuous, ribbon like Golgi apparatus. (1) On the cis‐face of the Golgi stack there was a tubular membranous network known to be osmiophilic and referred to as the cis‐osmiophilic tubular network or cis‐element. (2) A first, poorly fenes‐trated saccule, unreactive for the phosphatases tested, was slightly distended in places and contained a fluffy granulofilamentous material. (3) The subjacent three or four saccules, reactive for NADPase and/or TPPase, showed dilated portions containing a granulofilamentous secretory material similar to that filling the rest of the saccule. They also showed nondilated portions perforated with large fenestrations, some of which were in register and formed wells containing 80‐nm vesicles. The dilated portions of these saccules were present at random along the length of the saccules and were not located exclusively at their edges. (4) The remaining one or two elements of the stack, CMPase positive, showed dilated spheroidal portions or prosecretory granules containing a homogeneous secretory material and flattened fenestrated regions free of secretory material and having the appearance of networks of narrow membranous tubules. (5) Lastly on the trans‐aspect of the stack there were detached prosecretory granules reactive for CMPase and surrounded by a corona of small vesicles, and smooth‐surfaced spherical CMPase‐negative granules having a denser content that were identified as fully formed secretion granules; there were also occasional free trans‐tubular networks strongly reactive for CMPase that appeared to undergo fragmentation and numerous small vesicles free from acid‐phosphatase activity. These various images were interpreted as indicating that prosecretory granules formed in relation to two or three fenestrated saccules on the trans‐side of the stack. Such granules, following their detachment from the trans‐face of the stack, their separation from trans‐tubular networks, and condensation of their content, yielded mature secretion granules.
Histology and functional morphology of the female reproductive tract of the tortoise Gopherus polyphemus
Authors: Palmer B. D. , Guillette L. J.
Published: February 2005

The oviducts of 25 tortoises (Gopherus polyphemus) were examined by using histology and scanning electron microscopy to determine oviduc‐tal functional morphology. Oviductal formation of albumen and eggshell was of particular interest.

The oviduct is composed of 5 morphologically distinct regions; infundibulum, uterine tube, isthmus, uterus, and vagina. The epithelium consists of ciliated cells and microvillous secretory cells throughout the oviduct, whereas bleb secretory cells are unique to the infundibulum. The epithelium and endometrial glands of the uterine tube histologically resemble those of the avian magnum which produce egg albumen and may be functionally homologous. The isthmus is a short, nonglan‐dular region of the oviduct and appears to contribute little to either albumen or eggshell formation.

The uterus retains the eggs until oviposition and may form both the fibrous and calcareous eggshell. The endometrial glands are histologically similar to the endometrial glands of the isthmus of birds, which are known to secrete the fibers of the eggshell. These glands hypertrophy during vitellogenesis bin, become depleted during gravidity. The uterine epithelium may supply “plumping water” to the egg albumen as well as transport calcium ions for eggshell formation. The vagina is extremely muscular and serves as a sphincter to retain the eggs until oviposition.

Sperm are found within the oviductal lumen and endometrial glands from the posterior tube to the anterior uterus throughout the reproductive cycle. This indicates sperm storage within the female tract, although the viability and reproductive significance of these sperm are unknown.
Roots and calibers of the human coronary arteries
Authors: Zamir M. , Sinclair P.
Published: February 2005

The anatomical structure of the coronary‐aortic junctions in humans is studied by using corrosion casts of the coronary network. A model is proposed for the specification of these junctions in terms of vessel diameters and branching angles, and the model is used to produce morphological data on these junctions which hitherto have not been available. This anatomical model correlates poorly with the accepted theoretical model of arterial bifurcations in the cardiovascular system. The results suggest that the structure of the coronary‐aortic junctions is very different from the structure of typical arterial bifurcations and, by implication, that the flow conditions under which they function are very different. A good understanding of these junctions is important in coronary bypass surgery, where the coronary‐aortic junctions are emulated by creating a new anastomosis for the graft at the base of the ascending aorta, and in coronary artery disease, where atherosclerotic lesions occur not far from the coronaiy‐aortic junctions.
Ultrastructural features of chloride cells in the gill epithelium of the atlantic salmon, Salmo salar, and their modifications during smoltification
Authors: Pisam M. , Prunet P. , Boeuf G. , Jrambourg A.
Published: February 2005

To elucidate the ultrastructural modifications of the gill epithelium during smoltification, gills of the Atlantic salmon (Salmo solar) were examined by electron microscopy at three stages of this process, which were defined as follows: “parrs” were freshwater fish that had not yet started their transformation; “freshwater smolts” were freshwater fish that were ready to enter seawater; and “seawater smolts” were smolts that had been transferred from fresh water and maintained for 4 days in seawater (35%).

In the gill epithelium of parrs, there were two types of chloride cells. The large chloride cells contained deeply stained mitochondria and numerous apical, irregular, dense, membrane‐bound bodies that formed 77% of the chloride cell population and were distinguished easily from small chloride cells that have distinctly paler mitochondria and no dense bodies in their apical cytoplasm. In freshwater smolts, the large chloride cells formed 95% of the chloride‐cell population. In contrast to the small chloride cells that were not modified, they almost doubled in size. Their tubular system developed extensively to form a tight network with regular meshes significantly smaller than those observed in parr chloride cells. Forty percent of the large chloride cells were associated with a new type of cell, the accessory cell, to which they were bound by shallow apical junctions. Half of these accessory cells were not seen to be in contact with the external medium, In seawater smolts, 80% of the large chloride cells were associated with accessory cells. Most accessory cells reached the external medium and sent numerous cytoplasmic interdigitations within the apical portion of the adjacent chloride cells. As a result, a section through the apical portion of the chloride cells and their associated accessory cells revealed a mosaic of interlocked cell processes bound together by an extended, shallow apical junction.

It was concluded that the Atlantic salmon develops in fresh water most of the ultrastructural modifications of the gill epithelium which in most euryhaline fish are triggered by exposure to seawater. The effective transfer into seawater would act only as a final stimulus to achieve some adequacy between the freshwater smolt and its new environment.
Morphology and morphometry of the normal lung of the adult vervet monkey (Cercopithecus aethiops)
Authors: Maina J. N.
Published: February 2005

The lungs of four adult specimens of the vervet monkey (Cercopithecus aethiops) have been examined by transmission and scanning electron microscopy. A morphometric evaluation of the structural components directly involved in gas exchange has been carried out and the data have been modelled to estimate the anatomical diffusing capacity of the lung. The upper air‐conducting airways of the lung were lined by an epithelium characterized by ciliated cells among which were dispersed goblet cells. The alveolar surface was lined by squamous type I pneumocytes and cuboidal type II granular pneumocytes. The blood‐gas (tissue) barrier consisted of an epithelial cell, a common basal lamina, and an endothelial cell in the thin parts of the interalveolar septum. In the thicker parts of the septum, an interstitial space interposed between the basal laminae of the epithelial and endothelial cells contained supportive elements such as collagen, elastic tissue, and fibrocytes. The alveoli, the blood capillaries, and septal tissue composed 73%, 16%, and 11%, respectively, of the parenchyma. The harmonic and arithmetic mean thicknesses of the blood‐gas (tissue) barrier were 0.311 μm and 1.048 μm the surface area of the blood‐gas (tissue) barrier per unit body weight was 50 cm2g−1, and the surface density was 117 mm2‐mm3−1.The weight‐specific total morphometric diffusing capacity was 0.11 mlO2 (sec·mbar·kg)−1. In comparison, the pulmonary morphometric characteristics of vervet monkey lung were superior to those of the other primates (Macaca irus, M. mulatta, and Homo sapiens) for which equivalent data are available. The gas‐exchange potential of the lungs of the nonhuman primates as revealed by morphometric studies surpasses that of man, a feature that can be attributed to the relatively less energetic human lifestyle.
Occurrence of lymphohaemopoietic tissue in the meninges of the stingray Dasyatis akajei (Elasmobranchii, Chondricthyes)
Authors: Chiba A. , Torroba M. , Honma Y. , Zapata A. G.
Published: February 2005

The cytoarchitecture of the lymphohaemopoietic masses occurring in the “meninx primitiva” of the stingray Dasyatis akajei (Elasmobranchii, Chondricthyes) has been analyzed by light and scanning and transmission electron microscopy. Lymphohaemopoietic aggregates showing similar morphologies occurred along all the central nervous system, but they were more frequent in the telencephalon, diencephalon, and mesencephalon. In each aggregate, the granulopoietic tissue appeared in a fibroblastic stroma surrounding the large blood vessels, and the lymphoid components were present in a reticular network. Developing and mature eosinophils and heterophils–as well as lymphocytes, monocytes, macrophages, and plasma cells–are the main free cells present in these meningeal aggregates. The remarkable intimate association between macrophages and lymphoid cells to form close cell clusters suggests some immunological capacity for the meningeal lymphohaemopoietic tissue. According to their capacities, presence of lymphoid tissue, and histological organization, the meningeal lymphuhemopoietic aggregates of Dasyatis akajei resemble other lymphomyeloid aggregates associated with cranium and choroid plexuses in Holocephali and Ganoidei. The phylogenetical relationships of these aggregates with mammalian bone marrow are discussed.
Ontogeny of architectural complexity in embryonic quail visceral arch muscles
Authors: McClearn Deedra , Noden Drew M.
Published: February 2005

Understanding the mechanisms of muscle pattern formation requires that the complete sequence of ontogenetic events be defined, particularly in the emergence of architectural complexity and in the spatial relations between muscles and skeletal elements. This analysis of visceral arch myogenesis in quail (Coturnix coturnix japonica) embryos identifies the location of premuscle condensations and subsequent segregation of individual muscles, documents the initial orientation of myofibers and changes in alignment associated with maturation, and describes the spatial and temporal relations between muscle development and the formation of connective tissues.

Premuscle condensations form within the visceral arches on embryonic days 2–4, before skeletal elements make their appearance. Discrete muscles may form from the subdivision of a muscle mass after fiber orientations have been established (e.g., jaw adductor and hyobranchial muscles) or by the segregation of a mesenchymal cluster from the condensation prior to the appearance of oriented fibers (e.g., protractor, muscle of the columella).

The rate and pattern of subsequent muscle maturation are closely associated with the development of the hard tissues. Myogenesis in 4–9‐day embryos centers around the quadrate cartilage, the retroarticular process of the mandibular (Meckel's) cartilage, and the epibranchial cartilage. Muscles form attachments on these elements and remain without additional attachments until the appropriate elements (e.g., otic capsule, pterygoid bone) develop. No single description of myogenic events applies to all visceral arch muscles, nor is there an arch‐specific pattern of ontogeny. Rather, each muscle has distinctive characteristics based on its spatial relations within the developing head.
Application of glial fibrillary acidic protein immunohistochemistry in the quantification of astrocytes in the rat brain
Authors: Faddis Brian T. , Vijayan Vijaya K.
Published: February 2005

Immunohistochemical staining for glial fibrillary acidic protein (GFAP) was employed as a tool for quantification of astrocytes in the rat brain. One‐micron‐methacrylate sections were prepared from 70‐μm slices stained for GFAP by using a preembedding staining procedure. Numbers/unit area of astrocytes and nonastrocytes were determined for cortex, corpus callosum, and hippocampal neuropil. In each, counts from GFAP‐stained, toluidine‐blue‐counterstained sections were compared with counts obtained from sections stained with toluidine blue alone. Numbers of nonastrocytes and total glia in all three regions were comparable in both groups of sections. Astrocyte counts in the cortex and hippocampus also showed no significant differences between the two groups. In contrast, the number of astrocytes in the corpus callosum was significantly lower in GFAP‐stained, toluidine‐blue‐counterstained sections than in sections stained with toluidine blue alone. GFAP immunohistochemistry is a useful tool for the quantification of astrocytes in semithin plastic sections of rat brain.
Orthogonal arrays of intramembrane particles in the supporting cells of the guinea‐pig vestibular sensory epithelium
Authors: Saito Kogaku
Published: February 2005

Membrane specializations of the contact region between afferent nerve endings and supporting cells of the sensory epithelia of guinea‐pig vestibular endorgans were examined by thin‐section and freeze‐fracture electron microscopy. The calyx‐type nerve endings (C‐endings) are separated from supporting cells (SC) by a 25–30 nm space. At irregular intervals along the upper lateral surface of supporting cells, the intercellular space narrows markedly to form special close contacts between the C‐ending and SC plasma membranes. Freeze‐fracture replicas reveal membrane specializations—orthogonal arrays of particulate units—in the region where the close intercellular contacts were found in sections. Orthogonal arrays consisting of from 5 to 20 units were observed on the cytoplasmic (P) fracture face of the lateral SC plasma membrane. These particulate units form a 12 × 12‐nm square, and each unit is composed of four 6‐nm subunits. Possible roles of the orthogonal arrays are discussed.
Early stages of spinal ganglion formation during tail regeneration in the newt, Notophthalmus viridescens
Authors: Géraudie J. , Nordlander R. , Singer M. , Singer J.
Published: February 2005

Stages in the development of sensory ganglia in the regenerating newt tail after amputation are described by taking advantage of the rostrocaudal developmental gradient of the regenerating tail. A series of ganglia, beginning at the tip of the regenerate and progressing rostrally, were examined. Eight‐week regenerates were used because they showed the most complete array of stages. The first recognizable ganglia appear as small clusters of cells sitting dorsally on the already established ventral roots. The cluster of ganglionic cells steadily expands with the addition of many new cells. Signs of cell differentiation within the ganglion precede the formation of the dorsal root rudiment, which assumes several different configurations but most commonly enters the cord close to the ventral root. Our material suggests that ganglion precursor cells originate in the ventral region of the developing spinal cord and migrate out of the cord by travelling along the ventral root until, at a suitable distance from the cord, they halt, proliferate, and eventually differentiate. In the regenerate, we saw no evidence of neural crest cells—such as those that give rise to ganglia in the trunk region during development—forming at the dorsal region of the regenerated neural tube. Nor was there any morphological evidence of mesenchymal contribution to the ganglion cell clusters.
Myofiber turnover is used to retrofit frog jaw muscles during metamorphosis
Authors: Alley Keith E.
Published: February 2005

Metamorphic reorganization of the head in anuran amphibians entails abrupt restructuring of the jaw complex as larval feeding structural lM transformed into their adult configurations, In this morphometric study, light microscopy was used to analyze the larval maturation and metamorphic transfiguration of the adductor jaw muscles in the leopard frog (Rana pipiens). Larval jaw muscles, first established during embryogenesis, continue to grow by fiber addition until prometamorphosis, stage XIL Thereafter, fiber number remains stable but additional muscle growth continues by hypertrophy of the individual fibers until metamorphic climax. During metamorphic stages XIX‐XXIII, a complete involution of all larval myofibers occurs. Simultaneously, within the same muscle beds, a second wave of myogenesis produces myoblasts which are the precursors of adult jaw myofibers. New muscle fibers continue to be added to these muscles well after the completion of metamorphosis; however, the total duration of the postmetamorphic myogenic period has not been defined. These observations provide clear evidence that the entire population of primary myofibers used in larval oral activity disappears from the adductor muscle beds and is replaced by a second wave of myogenesis commencing during climax. These findings indicate that the adductor jaw muscles are prepared for adult feeding by a complicated cellular process that retrofits existing muscle beds with a completely new complement of myofibers.
Tracheobronchial epithelium in the adult rhesus monkey: A quantitative histochemical and ultrastructural study
Authors: Plopper C. G. , Heidsiek J. G. , Weir A. J. , St. George J. A. , Hyde D. M.
Published: February 2005

Previous studies of the intrapulmo‐nary conducting airways of sheep and rabbit have demonstrated marked diversity in the epithelial populations lining them. Because studies of trachea and centriaci‐nar regions of macaque monkeys suggested that primates may be even more diverse, the present study was designed to characterize the epithelial population throughout the airway tree of one primate species, the rhesus monkey. Trachea and intrapulmonary airways of the right cranial and middle lobes of glutaraldehyde/ paraformaldehyde‐infused lungs of five adult rhesus monkeys were microdissected following the axial pathway. Each branch was assigned a binary number indicating its specific location within the tree. The trachea and six generations of intrapulmonary airway from the right cranial lobe were evaluated for ultrastructure and quantitative histology as were those of the right middle lobe for quantitative carbohydrate histochemistry. Four cell types were identified throughout the tree: ciliated, mucous goblet, small mucous granule, and basal. The tallest epithelium lined the trachea; the shortest, the respiratory bronchiole. The most cells per unit length of basement membrane were in proximal intrapulmonary bronchi; the least, in the respiratory bronchiole. The nonciliated bronchiolar epithelial or Clara cell was restricted to respiratory bronchioles. Sulfomucins were present in the vast majority of surface goblet cells in the trachea and proximal bronchi. In proximal bronchi, neutral glycoconjugates predominated in glands and acidic glycoconjugates in surface epithelium. In terminal and respiratory bronchioles the ratio of acidic gly‐coconjugate to neutral glycoconjugate equaled that in proximal bronchi, although glands were not present. Sulfomucins were minimal in terminal airways. We conclude that the characteristics of the epithelial lining of the mammalian tracheobronchial airway tree are very species‐specific. The lining of the rhesus monkey does not have the diversity in cell types in different airway generations observed in sheep and rabbit. Also, the populations lining these airways in the rhesus are very different from either the sheep or rabbit in number, proportions of different cell types, glycoconjugate content, and distribution of specific cell types.