bluuebunny/crossref_metadata_2025 huggingface dataset:
The liver hemopoietic environment: I. Developing hepatocytes and their role in fetal hemopoiesis
Authors: Medlock Eugene S. , Haar Jack L.
Published: February 2005

Mouse fetal liver was studied ultrastructurally to identify and charaterize the developing hepatic parenchyma or prehepatocyte which may be responsible for producing the liver hemopoietic enviroment. It was observed that as the liver develops, there is close association of endodermal and mesenchymal cells in the region of the septum transversum. Numerous intercellular adhesions were observed between endodermal cells and mesenchymal cells. Twenty‐fours after endodermal and mesenchymal cells first intermingle, the liver extravascular space consisted of consisted of spherical hemopoietic cells dispersed among a heterogenous population of dark and light cells. The reticulum of prehepatocytes formed a three‐demensional cellular network which structurally supported the hemopoietic cells residing in the liver. By 12 days of gestation, prehepatocytes were a homogenous population of dark, stellate cells joined together by numerous intercellular adhesions. Broad areas of intercellular association were noted between processes and prehepatocytes and hemopoietic cells; however, no inercellular junctions between these two disparate cell populations were observed at this or any stage in development. Characteristics reflecting a cell population capable of synthesis and secretion of proteinaceous substances, namely, dilated Golgi apparati, increased numbers of polyribsomes and profiles of rough endoplasmic reticulum (RER), two types of vacuoles and/or vesicles, and intercellular microvillus‐lined spaces, were observed in the prehepatocytes between 12 and 17 days gestation. By day 17 of gestation, glycogen accumulation, biliary channel development, appearance of a subendothelial microvillus surface, nuclear shape and chromatin pattern, and arrangement of cytoplasmic organelles reflected the maturation of prehepatocytes into hepatocytes, the adult liver parenchyma.
A quantitative study of muscle spindles and tendon organs in some intrinsic muscles of the hand in the bonnet monkey (Macaca radiata)
Authors: Devanandan M. S. , Ghosh S. , John K. T.
Published: February 2005

The number and density of muscle spindles and tendon organs have been determined in the following intrinsic muscles of the hand of bonnet monkeys: I lumbrical, II lumbrical, abductor digiti minimi, adductor pollicis, and I dorsal interosseous. All these muscles were found to be very rich in muscle spindles (17.6 to 42.31 per gram wet weight) but relatively poor in tendon organs (0.606 to 10.06 per gram wet weight). The lumbricals have very few tendon organs. The possible functional significance of these findings has been discussed.
Effect of castration and testosterone replacement on high glucose 6‐phosphatase activity in principal cells of the mouse epididymis
Authors: Kanai Kazuo , Kanamura Shinsuke , Watanabe Jun , Asada‐Kubota Mari , Yoshikawa Motoko
Published: February 2005

Glucose 6‐phosphatase activity is higher in the principal cell than in other cell types in the terminal segment and caudal half of the middle segment of the mouse epididymis. Effect of castration and testosterone replacement on the high enzyme activity in the principal cell was studied in the terminal segment and the caudal half of the middle segment (cytochemical study), and in the whole epididymis (biochemical study). Ten, 20, or 30 days after castration, the abundant amount of reaction product seen in principal cells from intact control animals decreased to the level in basal cells, halo cells, and smooth muscle cells. However, in animals treated with testosterone following castration, the reaction product in principal cells remained abundant. Changes in the biochemical activity after castration or testosterone administration following castration paralledled the cytochemical results. Thus, the high activity in the principal cell is under the control of testosterone.
Intermediate filaments of the cytoskeleton in glandular cells of the rat fundic mucosa: Immunofluorescence and electron microscopy study
Authors: Dabiké Mónica , Koenig Cecilia S.
Published: February 2005

The organization of intermediate filaments (IF) in cells of the rat fundic mucosa was studied by electron microscopy and immunofluorescence microscopy using specific antiprekeratin antibodies on frozen sections and isolated cells.

Our results suggest that mucous cells lining the gastric surface and the gastric pits, which appeared strongly decorated, are the most rich in IF. These cells displayed coarse bundles of IF oriented in all directions as well as desmosome‐attached tonofibrils. Mucous neck cells contained fewer bundles of IF located preferentially toward the apical region. Zymogen cells showed a strong staining along the contour of the luminal border, together with a faint decoration of a fine meshwork extending throughout the cytoplasm. A poorly defined fibrillar cortex present underneath the secretory plasma membrane and sparse bundles of IF among the elements of the rough endoplasmic reticulum were seen in thin sections. In contrast, parietal cells appeareed brightly stained and the prekeratinlike material formed a cortical polygonal meshwork especially visible in isolated cells. A developed system of IF formed by conspicuous bundles located underneath the secretory canaliculi, among the mitochondria and in the vicinity of the basal plasma membrane, was observed in the electron microscope.
Two anatomical pathways for the renewal of surface glycoproteins in chloride cells of fish gills
Authors: Pisam M. , Chrétien M. , Rambourg A. , Clermont Y.
Published: February 2005

The cytoplasm of chloride cells found in the epithelium lining the gills of guppies (Lebistes reticulatus) contains, in addition to the Golgi apparatus and cisternae of endoplasmic reticulum, two distinct membranous components, the vesiculotubular and the tubular systems. While the latter is connected to the laterobasal plasma membrane, the former, made up of small vesicles and short membranous tubules, is seen mainly between the Golgi apparatus and the apical cavity which invaginates the apex of the cell. The role of these two systems in the transport of glycoproteins from the Golgi apparatus to the cell surface was investigated in fishes maintained in fresh and salt water, injected with 3H‐fucose, and sacrificed at various intervals thereafter (10 and 30 min; 2.5, 8, 15.5, 24, and 48 hours). The distribution of the label was analyzed by quantitative radioautography in sections examined with the light and electron microscopes. The light microscopic data suggested that the label incorporated in the supranuclear region, where the Golgi apparatus is located, migrated toward the apical and the laterobasal regions of the chloride cells. The relative concentration of the tracer over the various components of the cytoplasm of these cells was calculated from data collected on electron microscope radioautographs at various intervals after 3H‐fucose injection. The curves obtained supported the view that glycoproteins synthesized in the Golgi apparatus were transported to the apical surface via the vesiculotubular system, and to the laterobasal membrane via the tubular system.
The permeability of human amniotic epithelium: Studies using lanthanum as a tracer
Authors: King Barry F.
Published: February 2005

To study the permeability of human amniotic epithelium to small molecular weight substances, pieces of nonplacental amnion, with attached chorion laeve and decidua, were exposed to solutions containing lanthanum salts and processed for electron microscopy. Lanthanum penetrated the intercellular spaces and often reached the basal lamina region. In addition, some lanthanum was bound to the glycocalyx of the microvilli on the apical surfaces of the cells. Little lanthanum was found deep to the basal lamina. The results suggest the intercellular pathway is of major importance in the movement of small molecules across amniotic epithelium.
Scanning electron microscopic structure of the finger print as related to the dermal surface
Authors: Misumi Yuko , Akiyoshi Toshio
Published: February 2005

This paper aims to clarify the relationship of the dermis to epidermal ridge configuration. After fixation, human fingertip epidermis was peeled off from the dermis by alkaline treatment, and the dermal surface was observed with the scanning electron microscope (SEM). The SEM pattern of furrows, grooves, and papillae showed an exact negative fingerprint image. Papillae had various sizes and complicated shapes and were arranged continuously but irregularly on each side of the furrow. Size and shape variabilities were not dependent on the site of the fingerprint region. The papilla number tended to increase with age due to derivation of secondary papillae from the primary papilla as well as new formation of small papillae. The dermal surface exhibited some site‐specific fibrous appearance at the furrow and papilla, whereas the surface was smooth at the groove. The characteristics of the dermal surface structure as related to the epidermis can be explained by a stronger dermis‐epidermis adhesion at the furrow than at the papilla or at the groove.
Ontogeny of immunoreactive somatostatin in thyroid C cells from dogs and guinea pigs
Authors: Kameda Yoko , Oyama Hideki , Horino Masaharu
Published: February 2005

The development of immunoreactive somatostatin in thyroid C cells of dogs and guinea pigs from early fetuses to adults was investigated by the use of immunoperoxidase histochemistry and radioimmunoassay. The time of appearance and developmental patterns of immunoreactive somatostatin in the C cells were completely different in both species. In guinea pig thyroids, the somatostatin immunoreactivity appeared later than the calcitonin immunoreactivity and the number of somatostatin‐positive cells was very small during fetal periods. The somatostatin immunoreactivity rapidly increased during neonatal periods. A large population of the somatostatin cells and a high concentration of somatostatin immunoreactivity were observed in mature animals. On the other hand, in dog fetuses somatostatin immunoreactivity appeared very early, at the same time as the calcitonin immunoreactivity. The largest population of somatostatin cells was found at the stage when the primordial follicles were vigorously formed throughout whole thyroid parenchyma. At this stage almost all of calcitonin‐positive cells were also somatostatin‐positive. The somatostatin cells progressively decreased as the development proceeded, in contrast to the calcitonin cells which increased with gestational age. In postnatal dogs only a few C cells revealed the immunoreaction for somatostatin, and the concentration of somatostatin was very low. These findings suggest that the function of somatostatin in dog thyroid C cells may be different from that in guinea pig C cells.
Myosatellite cells, growth, and regeneration in murine dystrophic muscle: A quantitative study
Authors: Ontell Marcia , Feng K. C. , Klueber Kathleen , Dunn Robert F. , Taylor Floyd
Published: February 2005

Patterns of growth and regeneration in 2‐, 4‐, 8‐, and 17‐week‐old murine dystrophic (129 ReJ dy/dy) extensor digitorum longus muscles have been determined. Necrosis and myofiber loss, hypertrophy, and regeneration result in a reduced population of myofibers whose diameter distribution is more extensive than that found in the extensor digitorum longus muscles of age‐matched normal mice. At the onset of dystrophic symptoms (2 weeks postnatal), the ratio of myosatellite cell nuclei to the total sublaminal nuclear population (myonuclei + myosatellite cells) is similar to that found in 2‐week‐old control muscles. The frequency of finding myosatellite cells decreases with age in both control and dystrophic muscles. Myosatellite cells account for 11%, 6%, 5%, and 3% of the total sublaminal nuclear population in control muscle and 12%, 8%, 6%, and 5% of the total sublaminal nuclear population in dystrophic muscle at 2, 4, 8, and 17 weeks, respectively. No preferential association of myosatellite cells with myofibers of a particular diameter is found in control muscle or in the two youngest dystrophic groups. At 8 and 17 weeks, myosatellite cells are less frequently encountered on small‐diameter, regenerating myofibers of dystrophic muscle, and they are preferentially associated with large diameter, hypertrophied myofibers. The labeling index of myosatellite cells decreases with age in both normal and dystrophic muscle. At all ages the myosatellite cell labeling index is higher in dystrophic muscle (23%, 7%, 5%, and 2% at 2, 4, 8, and 17 weeks, respectively) than in normal muscle (5%, < 1% at 2 and 4 weeks, respectively), with no labeled myosatellite cells being found in 8‐ and 17‐week‐old normal muscles. It is suggested that the magnitude of the regenerative response of dystrophic murine muscle decreases with age and that this factor may be responsible for the inability of the regenerative response of dystrophic muscle to keep pace with the rapid muscle deterioration.
Ultrastructure of the secretory epithelium, nerve fibers, and capillaries in the mouse sweat gland
Authors: Quick Donal C. , Kennedy William R. , Yoon Kwon S.
Published: February 2005

The ultrastructure of the mouse sweat gland was examined, in support of neurological studies of sweat glands and their relationships to the autonomic nervous system. It was found that the mouse sweat gland is similar to that of the rat and has only one type of secretory cell. Many nerve fibers are entwined with the secretory tubule and contain accumulations of round, clear vesicles, some microtubules, but apparently no neurofilaments. Cholinesterase is found in the clefts between nerve fibers and their ensheathing Schwann cells. The nerve fibers tend to run parallel with capillaries, but have no close association with either the capillaries or the secretory epithelium. Capillaries provide an abundant blood supply to the sweat gland and are fenestrated. The relationships between cellular elements of the sweat gland provide no direct evidence of the mechanisms involved in neurogenic sweating, although it seems likely that effector substances are diffusely distributed.
A comparison of the density of microtubules in the central and peripheral axonal branches of the pseudounipolar neurons of lizard spinal ganglia
Authors: Pannese E. , Ledda M. , Arcidiacono G. , Rigamonti L. , Procacci P.
Published: February 2005

The number and density of microtubules were determined in cross sections of the two branches (central and peripheral) of the bifurcating axon of the pseudounipolar neurons of the lizard thoracic spinal ganglia. In both the central and peripheral branches the average number of microtubules rose, while the microtubular density decreased with an increase in the cross‐sectional area of the axonal branch: More precisely, a linear relationship was observed between the logarithm of the microtubular density and the cross‐sectional area of the axonal branch. Both the average number of microtubules per cross section of the axonal branch and the microtubular density were found to be significantly lower in the central than in the peripheral branch. Since the amount of material carried by fast transport was found by other authors to be greater in the peripheral than in the central branch, a positive correlation seems to exist between microtubular density and the quantity of material carried by fast transport along the two branches of the axon in pseudounipolar neurons. Such a correlation suggests that microtubules may be somehow involved in the fast transport of material along the axon.

The average densities of microtubules were found to be the same comparing two sets of unmyelinated and myelinated central (or peripheral) branches of corresponding size. Therefore, different microtubular densities usually observed in unmyelinated and myelinated axons appear to be correlated with the different size ranges of the two types of axon rather than with the absence or presence of the myelin sheath.
The organization of actin filaments in human polymorphonuclear leukocytes
Authors: Ryder Mark I. , Weinreb Robert N. , Niederman Richard
Published: February 2005

Actin constitutes a major component of the cytoskeleton of human polymorphonuclear leukocytes (PMNs). In this study, we present a comprehensive view of the organization of actin in various PMN regions and functional states. Transmission electron microscopic observations were made on whole mount, migrating, and phagocytizing PMNs. Positive identification of actin filaments was made through S‐1 myosin subfragment labeling. In all PMNs studied, actin filaments were primarily organized as a three‐dimensional meshwork. The density of this meshwork was greatest within the cell cortex. At peripheral regions of nonpolarized (viz., no distinct head or tail region) and polarized PMNs, actin filaments organized into parallel bundles or overlapping arcs. These bundles or arcs were oriented either perpendicular or parallel to the cell periphery. At the base of the PMN, actin filaments converged upon dense, plaquelike condensations. This latter pattern of actin organization was also observed in some pseudopods at the cell front and in phagocytic processes engulfing bacteria. In areas of internalized bacteria, the surrounding actin appeared as a loose meshwork. Treatment of PMNs with the antiactin drug, cytochalasin B, revealed shearing of the peripheral actin meshwork, condensation of the meshwork around the nuclear region, and dissolution of the basal plaquelike condensations.
From bone lining cell to osteocyte—an SEM study
Authors: Menton D. N. , Simmons D. J. , Chang S.‐L. , Orr B. Y.
Published: February 2005

We describe the SEM appearance of the rat endosteal bone lining cell (BLC) population, and the sequence of morphological changes of these cells as they self‐incorporate into unmineralized bone matrix (osteoid), establish intercellular connections, and construct lacunae. The osteoblast/nascent osteocyte series was progressively unsheathed by gentle digestion of the osteoid with 0.25% collagenase. The osteoblasts which leave the polygonally packed BLC compartment rapidly develop numerous complexly branched processes that contact the processes elaborated by previous generations of maturing and mature osteocytes. As osteoblasts mature and approach the mineralization front, they appear to lose processes. The mature cells begin to form osteocyte lacunae by depositing an asymmetric perimeter of woven collagen fibrils, such that as the cells roof‐over, the lacunae appear as pocketlike constructions. The collagen fibrils on the perilacunar matrix are oriented in a tangential or circular pattern, while those in the more distal matrix are arranged in a parallel pattern. With the completion of a lacuna, its wall appears to mineralize quickly, for lacunae could be recognized only when they are forming.
New evidence for monozygotic twins in the mouse: Twinning initiated in the late blastocyst can account for mirror image asymmetries
Authors: Runner Meredith N.
Published: February 2005

The 11.5‐day twin mice reported here support one of the classically described mechanisms for mammalian monozygotic twinning: subdivision of the blastocyst inner cell mass at the stage of proamnion cavitation. This particular method for monozygotic twinning has the attraction of providing a hypothesis for mirror image translocation of asymmetric traits. Monozygotic twins in laboratory rodents at or near parturition have not been identified and only two prior descriptions, for 7.5‐ and 9.5‐day mouse embryos, have been found in the literature. Experimentally induced twins having identical heredity, i.e., clones, would enable study of heritable and environmental regulation of the components of discordance. A set of twin mouse embryos at 11.5 days of gestation within a common yolk sac, and with shared vitelline and allantoic circulations, provides direct evidence that monozygotic twin mice can survive rotation within the common yolk sac and suggests a reasonable probability that they can survive to term.
Density of arteriovenous anastomoses in some skin areas of the domestic fowl (gallus domesticus)
Authors: Midtgård Uffe
Published: February 2005

The vascularity and the density of arteriovenous anastomoses (AVAs) were studied in the skin of the domestic fowl by using vascular injections and histological sections. The density of AVAs and associated blood vessels were low in the wattles and in the thoracic skin (five to 23 AVAs per cm2 and five to 14 AVAs per cm2, respectively), whereas the eyelids were highly vascular and contained many AVAs (170‐172 AVAs per cm2). It is suggested that the blood vessels in the eyelids are important in the temperature regulation of the eye and that AVAs in the thoracic skin may contribute to the control of blood flow through the brood patch.
Morphometry of the functional and regressing corpus luteum of the guinea pig
Authors: Azmi Tengku I. , O'Shea Jeremy D. , Bruce Neville W. , Rodgers Raymond J.
Published: February 2005

A morphometric study of functional and regressing corpora lutea (CL) of guinea pigs (n = 5 per day) was performed on days 9, 12, and 16 of the estrous cycle. On day 9 the functional CL contained ⋍ 750,000 cells, which included 565,200 ± 56,700 (S.D.) endothelial cells or pericytes and 137,300 ± 7,700 luteal cells. Between days 9 and 12 the only significant change suggesting the onset of regression was a reduction in vascular luminal surface area. During this time the number of luteal cells per CL increased to 204,400 ± 34,800 (P < .05), with an accompanying reduction in luteal cell volume from 19.8 ± 1.8 to 14.4 ± 2.4 pl/cell (P < .01). The increase in cell numbers was explicable by cell division, with mitotic indices of 0.83% and 0.97% on days 9 and 12, respectively. Luteal volume was unaltered. Between days 12 and 16, the mean volume of a single CL fell from 3.98 ± 0.2 to 1.42 ± 0.3 mm3 (P < .01) and luteal cell volume was reduced to 5.3 ± 1.1 pl/cell (P < .01). Between these 2 days the number of endothelial cells per CL fell from 539,900 ± 75,500 to 144,400 ± 63,300 (P < .01), with an accompanying reduction in vascular luminal surface area and in the volume occupied by vascular lumina. The total number of luteal cells per CL was not reduced significantly. It was concluded that luteal cell numbers in the guinea pig increase up to the time of onset of luteal regression, and that during regression up to day 16, shrinkage of luteal cells is the major cause of loss of luteal volume. During regression, endothelial cell loss occurs much more rapidly than loss of luteal cells.
Blood supply and drainage of the outer medulla of the rat kidney: Scanning electron microscopy of microvascular casts
Authors: Yamamoto Kazuhide , Wilson Douglas R. , Baumal Reuben
Published: February 2005

Blood supply and drainage of the outer medulla of the rat kidney were studied by scanning electron microscopy of vascular casts, using both arterial (n = 10) and venous (n = 10) injections of resin. Both outer and inner stripes of the outer medulla were supplied through different arterial capillary networks arising from efferent arterioles and arterial (descending) vasa recta. In contrast to previous studies using silicone rubber and light microscopy, a rich arterial capillary network supplying the outer stripe was demonstrated. Capillaries in the outer stripe and outer part of the inner stripe drained into venous vasa recta between vascular the bundles, while capillaries in the inner part of the inner stripe drained into venous vasa recta within the bundles. The results indicate that each zone in the outer medulla is supplied through separate capillary networks. The demonstration of a rich capillary network in the outer stripe of the outer medulla suggests that the predilection of this zone for tubular necrosis with ischemic or toxic injury is not related to a sparse capillary blood supply.
The influence of the hair cycle on the thickness of mouse skin
Authors: Hansen L. S. , Coggle J. E. , Wells J. , Charles M. W.
Published: February 2005

The data on mouse skin thickness reported here was prompted by the need to know the true postion of basal cells of the epidermis and hair follicles as these are important “cells at risk” for a variety of skin reactions including carcinogenesis following exposure to radiation. There is little reliable data in the literature and most previous reports have ignored the shrinkage of skin that occurs because of its natural elasticity.

The values determined for mouse flank skin in telogen‐the resting phase of the hair cycle for the different skin layers‐are epidermis 10 μm, corium 250 μm, adipose layer 150 μm, and hair follicle depth 150 μm. Three days after chemical depilation which triggers the hair follicles into active cycle (anagen) the epidermis doubles in thickness, remains at this value for 7 days, and then gradually returns to telogen values by day 18. The corium and adipose layers also increase significantly to reach approximately 390 μm and approximately 260 μm, respectively, by day 10 and then return to control values from day 15 onward. The change in hair follicles depths are more dramatic with active follicle basal cells reaching approximately 450–550 μm into the adipose layer between days 7 and 15.

One important finding is that chemical depilation does not affect the telogen thickness of skin‐the teleogen values for the epidermis and dermis immediately prior to and immediately after depilation were similar to those 23 days later at the beginning of the next telogen phase.
Formation of new rod photoreceptor synapses onto differentiated bipolar cells in goldfish retina
Authors: Kock Jan‐Henrik , Stell William K.
Published: February 2005

In goldfish new rods are continuously added to the entire retina at a rate that assures stable rod density, while the densities of other neurons decrease. The b1 bipolar, known to contact every rod within its dendritic domain, was used to determine the fate of these newly formed rods.

Golgi‐stained b1 bipolars were sectioned serially at 0.5 μm in the plane of the receptor terminals and reconstructions of their rod and cone contacts were prepared from camera lucida drawings.

The newly formed rods are accommodated within the dendritic trees of alreadyformed b1 bipolars at a rate of about one new rod synapse/bipolar/month. During growth from about 6 months to 5 years of age the number of synapses onto each b1 bipolar increases by 50%. Concomitantly the dendritic tree area increases by about 50%, and the density of rod‐b1 synapses remains constant at about one synapse/11 μm2. Assuming a dendritic coverage factor of 1, the b1 bipolars will contact every retinal rod. The numbers of cones contacted and not contacted do not significantly change. The overall dimensions of b1 bipolars increase with retinal growth and new branches are added to their dendritic trees.

These observations show that new rods added to adult goldfish retina form synapses with old bipolars. Some functional inferences are also made.
Distribution of fibronectin on the migratory pathway of primordial germ cells in mice
Authors: Fujimoto Toyoaki , Yoshinaga Kazuya , Kono Ichiro
Published: February 2005

The distribution and localization of fibronectin (FN) on the migratory pathway of primordial germ cells (PGCs) in mouse embryos were studied immunocytochemically at the light and electron microscopic levels. In embryos 9.5 to 11.0 days of gestation, the dorsal mesentery as the final region through which PGCs migrate was rich in FN. At this stage, migrating PGCs often showed amoeboid features with pseudopods in contact with neighboring mesentery (mesenchymal) cells. With the electron microscope, the reaction product to FN was visualized on the surfaces of somatic cells and of PGC pseudopods and at the site of contact between PGCs and somatic cells. Abundant extracellular FN was also found, probably binding with the extracellular matrices. By 11.5 to 12.0 days, when PGCs had arrived in the gonadal anlage, FN reaction had weakened or disappeared in the dorsal mesentery. Thus, the results suggest that FN plays a significant role in the migration of PGCs at least in the last portion of the migratory pathway.
Morphometric evaluation of diabetes‐associated ovarian atrophy in the C57BL/KsJ mouse: Relationship to age and ovarian function
Authors: Garris David R. , Williams Sarah K. , West Lee
Published: February 2005

Progressive, diabetes‐associated ovarian atrophy was analyzed in C57BL/KsJ diabetic (db/db) and control (+/?) mice between 2 and 16 weeks of age. Tissue changes were histologically and morphometrically analyzed and compared with ovarian functional indices (i.e., serum estradiol and progesterone) and metabolic (i.e., glucose uptake and estradiol sequestration) parameters. No significant differences were found between the ovarian follicular populations of either group at 2 and 4 weeks of age. However, between 4 and 8 weeks, the ovaries of diabetic mice exhibited marked stromal and follicular degeneration and an associated decline in the population of viable follicles as compared with controls. Between 8 and 16 weeks of age the follicular atrophy in the diabetics became more marked, as compared with controls, with the accumulation of intracellular lipid pools accenting the tissue degeneration and adiposity observed in both follicular and stromal compartments. In addition, ovarian function was depressed after 6 weeks of age in diabetic females as compared with controls as indicated by lowered serum estradiol and progesterone levels. Ovarian glucose uptake was enhanced in diabetic females while the ability of the ovary to sequester radiolabeled estradiol declined between 4 and 16 weeks of age as compared with controls. These data indicate that ovarian dysfunction in the (db/db) mutant mouse is associated with follicular atrophy, adiposity, impaired steroidogenesis, and imbalanced glucose utilization. These events occur in temporal association with the onset and progressive exacerbation of the hyperglycemic condition. It is suggested that ovarian involution in these mutants is directly related to an impaired follicular ability to metabolize properly the elevated intracellular glucose concentrations that develop in the (db/db) mice as compared with controls.
The vascular supply of the rat tympanic membrane
Authors: Albiin Nils , Hellström Sten , Salén Bengt , Stenfors Lars‐Eric , Wirell Staffan
Published: February 2005

The vascular supply of the rat tympanic membrane (TM) was studied by means of otomicroscopy, angiography, acrylic casts, and light microscopy. The branches of the external carotid artery in the external auditory meatus were found to vascularize (1) the pars flaccida, (2) the manubrial part of the pars tensa, and (3) the junction between the fibrocartilaginous ring of the TM and the tympanic sulcus of the temporal bone. The TM vessels of areas 1 and 2 were found beneath the squamous epithelium, close to mast cells and nerve bundles. Vessels originating from the tympanic cavity (also probably emanating from the external carotid artery) supplied the periphery of the pars tensa with minute branches, localized immediately beneath the tympanal epithelium. The portion of the pars tensa between the manubrial part and the periphery lacked a vascular system. Upon mechanical stimulation (gentle pressure on the handle of the malleus), the normally visible vessels dilated and minute branches appeared. This dilation may be caused, at least partly, by a release of vasoactive substances from mast cells and/or nerves in its vicinity. Even under mechanical stimulation, a large portion of the pars tensa seemed to be devoid of vessels. The nutrition of this part may be served by diffusion, with nutrients originating from the vessels in the tympanal rim and along the handle of the malleus. The architecture of the attachment of the fibrocartilaginous ring to the bony sulcus of the temporal bone is quite unique. Thus, the flow in the dense vascular network between these structures may be affected by an altered tension in the pars tensa.
Occurrence of cardiac muscle in the hepatic portal vein wall of the mouse and rat
Authors: Yokota Reiko , Yamauchi Akio
Published: February 2005

Cardiac myocytes have been shown to occur in the tunica media and adventitia at the region near the hepatic end of the portal vein of the mouse and rat, and have been studied by electron microscopy in the mouse portal vein. They measured 3–10 μm in breadth at their nuclear level, possessed centrally located nuclei, and were connected with each other by the intercalated disk. In these myocytes in the mouse portal vein, sarcoplasmic reticulum was represented by a rather simple and loose network of the anastomosing tubules. The membrane‐bound granules, which closely resemble the atrial specific granules, were found in many of the mouse portal vein myocytes. Transverse tubules, 40–200 nm in diameter, were sometimes detectable at the Z line level. The nexus occupied about 3–5% of the whole junctional area between cardiac myocytes in the tunica media, whereas in the tunica adventitia the corresponding value was about 17%. Blood capillaries with fenestrated endothelium supplied the cardiac myocytes in the adventitia of mouse portal vein. The closest relationship between the adrenergic axon and portal vein cardiac myocytes was observed to be ca. 0.3 μm apart. The significance of these findings is discussed in relation to pulsations of the portal vein.
Morphometric and autoradiographic analysis of frontonasal development in the chick embryo
Authors: Patterson Scott B. , Minkoff Robert
Published: February 2005

Dimensional changes in the nasal processes were measured in chick embryos from Hamburger and Hamilton (1951) stages 20 through 27.5. Transverse measurements in the frontonasal region of freshly fixed embryos were compared to frontal sections of the nasal region of comparably staged embryos. These observations were correlated with autoradiographic studies of cell movement employing an implant labeling technique.

Morphometric analysis indicated that between stages 20 and 25 the separation of the nasal pit orifices increased concidentally with rapid forebrain enlargement. Since the separation of the nasal pit fundi increased more rapidly, the orientation of the nasal pits changed. Autoradiographic studies indicated that lateral movement of medial nasal process mesenchyme into the base of the nasal groove and medial area at the base of the lateral nasal process had occurred. After stage 25, the separation of the nasal orifices declined dramatically, coincidental with rapid orbital enlargement. In contrast, the separation of the nasal pit fundi was maintained. It is proposed that nasal development of the chick embryo may be governed initially by forebrain enlargement and associated lateral movements of mesenchyme in the medial nasal processes, resulting in reorientation of the invaginating nasal placodes; subsequently, orbital enlargement and an associated medial redirection of growth of the lateral nasal processes assumes greater significance to the continued development of the frontonasal region.
Scanning electron microscopy of the subarachnoid space in the dog: Inflammatory response after injection of defibrinated chicken erythrocytes
Authors: Persky Bruce , Low Frank N.
Published: February 2005

The leptomeningeal reaction and the cerebrospinal fluid reaction of the canine inflammatory response were investigated concurrently. One‐half milliliter cerebrospinal fluid (CSF) was withdrawn from the cisterna magna of 17 anesthetized mongrel dogs and analyzed. Using this same spinal tap, control and experimental animals were injected with 0.5 ml sterile saline and 0.5 ml defibrinated chicken erythrocytes, respectively. A second spinal tap was performed 2 to 168 hr later. The CSF from the first spinal tap contained less than 1 WBC/mm3. The cell population was unchanged in the second spinal tap of control animals. In experimental animals, the WBC population increased more than 100‐fold by 24 hr. Polymorphonuclear cells (PMNs) appeared in the CSF first, followed by lymphocytes and monocytes. Injected erythrocytes seemed trapped in the subarachnoid space (SAS), especially in the inner sheet of the arachnoid mater. The leptomeninges had a substantial increase in free cells without fibrosis. Pial and leptomeningeal cells of the arachnoid trabeculae appeared swollen. Two hours after injection, chicken erythrocytes were phagocytosed by pial cells, macrophages, and free cells adherent to the leptomeninges. The epiplexus cell populations for saline‐control and erythrocyte‐experimental animals were similar, suggesting that the choroid plexuses were not a gateway for PMN, lymphocyte, or monocyte infusion into the SAS.
An ultrastructural analysis of dog mastocytoma cells and normal mast cells
Authors: Calonico Lynne D. , Phillips Martin J. , McDonald Donald M. , Gold Warren M.
Published: February 2005

A well‐differentiated dog mastocytoma was characterized ultrastructurally using morphometric, histochemical, and biochemical methods. The ultrastructure of cells in the intact tumor was compared to the morphology of cells disaggregated from the tumor and cultured for periods as long as 4 weeks and to normal dog connective tissue mast cells. Most of the tumor cells contained histamine (mean = 5.81 pg/cell), demonstrated chloroacetate esterase activity histochemically, stained metachromatically with toluidine blue, and were similar in ultrastructure to normal dog mast cells. The proportion of mast cells in this tumor averaged 67%; eosinophils, fibroblasts, plasma cells, and macrophages also were present. The mean diameter of mast cells (12.79 μm) and the mean diameter of their cytoplasmic granules (473 nm) were similar to those reported for mast cells and mastocytoma cells from various species. The heterogeneity in appearance of the mastocytoma granules is consistent with a variable degree of granule maturation. After disaggregation or periods of culture ranging from 2 days to 4 weeks, the mean granule diameters were 15% larger than those measured in the intact mastocytoma cells, though other morphological features remained unchanged. Although the cells retained their distinct morphological features for at least 4 weeks, some of their physiological responses were lost after 1 week in culture. Our study showed that dog mastocytomas can be a source of a large, relatively homogeneous population of cells that are useful for elucidating some of the structural and functional properties of mast cells.
Three‐dimensional structure of the murine muscle‐tendon junction
Authors: Trotter J. A. , Samora A. , Baca J.
Published: February 2005

At the muscle‐tendon junction of skeletal muscle fibers the structural interface between muscle cell and connective tissue is amplified by tapering, by indentation, and by surface folding. The precise form taken by the surface folds has been unknown due to a lack of studies on the three‐dimensional geometry of the muscle‐tendon junction. Analysis of this region by scanning electron microscopy, using conventional preparative techniques, is uninformative because the muscle surface is covered by connective tissue. Removal of the connective tissue from individual murine muscle fibers by incubation of fixed fibers in hot HCI, followed in some instances by treatment with collagenase, permits SEM analysis of the uncovered fiber ends. The muscle fiber end is characterized by surface specializations in the form of anastamotic cylindrical folds. Transmission electron micrographs of cross sections and of serial longitudinal sections of muscle fiber ends confirm that the SEM observations are correct.
Glycoprotein synthesis in the Golgi apparatus of spermatids during spermiogenesis of the rat
Authors: Clermont Yves , Tang X. M.
Published: February 2005

During steps 1–7 of spermiogenesis the Golgi apparatus contributes to the formation of the acrosomic system which develops at the surface of the nucleus. Later, in step 8, the Golgi apparatus detaches from the acrosome and remains suspended in the elongated cytoplasm until it degenerates during step 16. Using 3H‐fucose as a tracer and the radioautographic technique, we observed that the Golgi apparatus incorporates the tracer and delivers the labeled glycoproteins to the developing acrosomic system during steps 1–7 of spermiogenesis, to multivesicular bodies during steps 1–9, and to the remaining cytoplasm and plasma membrane during steps 1–15. Throughout these steps of spermiogenesis the Golgi apparatus does not show major changes in structure; it is composed of a cortex made up of connected stacks of saccules and a medulla showing a loose aggregate of vesicular profiles. Glycoprotein synthesis in this Golgi apparatus, before and after it contributes lysosomal glycoproteins to the growing acrosomic system, was quantitatively assessed in electron microscope EM radioautographs of tissue sections from animals sacrificed at 1, 4, 8, and 24 h of 3H‐fucose injection. The incorporation of the labeled sugar was found to remain quantitatively similar during steps 1–15 of spermiogenesis, and therefore, no shift in glycoprotein synthesis took place following separation of the Golgi apparatus from the acrosomic system. Throughout these steps, fucose molecules are first incorporated in the cortex of the organelle and subsequently transported to the medulla, where they temporarily accumulate before being delivered, depending on the step of spermiogenesis, to the acrosomic system, to the multivesicular bodies, and also, presumably, to the plasma membrane.
Distribution of actin in isolated seminiferous epithelia and denuded tubule walls of the rat
Authors: Vogl A. W. , Soucy L. J. , Lew G. J.
Published: February 2005

We have studied the distribution of actin, using NBD‐phallacidin as a probe, in isolated sheets of seminiferous epithelia and denuded tubule walls of the rat. Sheets of intact seminiferous epithelia were separated from tubule walls using EDTA in PBS. The isolated epithelia and denuded tubule walls were fixed, mounted on slides, made permeable with cold acetone (−20°C), and then treated with NBDphallacidin.

Actin was observed in myoid cells, in ectoplasmic specializations of Sertoli cells, and in Sertoli cell regions adjacent to tubulobulbar processes of late spermatids. In myoid cells, filament bundles course in circular and longitudinal directions relative to the tubule wall. In Sertoli cells viewed at an angle perpendicular to the epithelial base, actin filaments in ectoplasmic specializations adjacent to junctional complexes circumscribe the bases of the cells. Filament bundles in ectoplasmic specializations adjacent to germ cells closely follow the contour of and are arranged parallel to the long axis of the developing acrosome. Sertoli cell regions adjacent to tubulobulbar processes of late spermatids stain intensely with NBD‐phallacidin.

Isolated seminiferous epithelia, combined with NBD‐phallacidin as a probe for actin, provide an ideal model system in which to study further the contractile properties of Sertoli cell ectoplasmic specializations and the possible involvement of these structures in events that occur during spermatogenesis.
Ultrastructure of the anterior buccal gland of the rat
Authors: Nicholas Suzanne , Redman Robert S.
Published: February 2005

The anterior buccal gland of the rat is a mucous salivary gland which develops as a branch of the main (Stensen's) duct of the serous parotid gland, a few mm from its oral orifice. The purpose of the present study was to further characterize the mature gland by means of electron microscopy and the histochemical demonstration of myoepithelial cells. The tubuloacini were found to have intercellular extensions (canaliculi) of the lumina, prominent Golgi complexes, and mucous secretory granules with a biphasic substructure. Discharge was by exocytosis of individual granules. The tubuloacini joined directly to striated ducts; no intercalated ducts were seen. First‐order excretory ducts had larger lumina and shorter columnar cells, with fewer mitochondria and basal infoldings, than the striated ducts. Myoepithelial cells invested the tubuloacini but not the ducts. The anterior buccal gland has several features that are unusual for a minor salivary gland of mucous type, and which are usually associated with serous glands such as the parotid. It should provide a particularly interesting model for investigating factors which control the differentiation of secretory and myoepithelial cells, and the glycosylation of polypeptides to form mucous secretory products.
Osteoblast and osteoclast precursors in primary cultures of calvarial bone cells
Authors: Burger Elisabeth H. , Boonekamp Piet M. , Nijweide Peter J.
Published: February 2005

Bone cells obtained by digestion of fetal mouse or chicken calvaria were tested for their ability to form or resorb bone in vitro. The isolated cells were precultured for 6 days and subsequently cocultured for 11 days with periosteum‐free noninvaded fetal mouse long bone rudiments. Bone formation and resorption during coculture were evaluated by histology and 45Ca release from prelabeled bones. The calvarial origin of cells in cocultures was traced by labeling the cells with 3H‐thymidine before coculture, followed by autoradiography.

Many osteoblasts and osteoclasts as well as fibroblasts developed from mouse periosteal cells released late in the sequential digestion procedure and previously denoted as “osteoblastlike” (BL). No or few osteoblasts and osteoclasts but many fibroblasts developed from early released cell fractions that have previously been denoted as “osteoclastlike” (CL).

Only osteoblasts and fibroblasts but not osteoclasts developed from chicken calvarial cell fractions. The osteoblasts developed primarily from cell fractions from the inner layer of the periosteum, previously denoted as “osteoblastlike” (OB). Cells obtained from the outer layer of the periosteum (PF) gave rise mainly to fibroblasts.

These studies show that osteoblast and osteoclast precursor cells are maintained in monolayer cultures of periosteal cell fractions. However, sequential digestion of mouse calvaria does not lead to separation of the two types of bone cells. Rather, osteoclast and osteoblast precursors are released jointly, from the periosteal cell layers closest to the bone surface. In the chicken cell fractions osteoclast precursors are absent after preculture, resulting in a more homogeneous population of osteoblast and fibroblast but not osteoclast precursors.
Three‐dimensional observation of the intrahepatic lymphatics by scanning electron microscopy of corrosion casts
Authors: Yamamoto Kazuhide , Phillips M. James
Published: February 2005

The three‐dimensional arrangement of intrahepatic lymphatics was demonstrated in the rabbit liver by scanning electron microscopy of corrosion casts. These casts were prepared by injecting resin into the common bile duct at a pressure that caused resin to leak from the bile ducts in the small portal tracts and drain into the lymphatics. The lymphatic channels were composed of straight vessels and anastomosing short side branches. The anastomoses were especially rich at the bifurcation of the portal tracts and formed a network. The terminal branches were blind‐ended. Constrictions suggesting valves were occasionally observed.
Gap junctions in rat sublingual gland
Authors: Nagato Toshikazu , Tandler Bernard
Published: February 2005

Gap junctions were observed in rat sublingual gland to link serous cells to serous cells, mucous cells to mucous cells, and myoepithelial cells to myoepithelial cells. In addition to connecting homologous cells, gap junctions were present between conterminous serous and mucous cells. Since the rat sublingual gland is innervated solely by parasympathetic nerves, the presence of gap junctions between disparate secretory cell types raises the possibility that serous and mucous cells in this organ secrete simultaneously in response to parasympathetic stimulation.