bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fiber types in red and white segments of rat sternomastoid muscle
Authors: Dulhunty Angela F. , Dlutowski Monica 
Published: February 2005

AbstractThe contractile, histochemical and morphological properties of fibers from red and white rat sternomastoid segments have been studied. Previous mechanical experiments suggested that both segments were fast‐twitch and the present experiments were done to confirm this observation and to determine other essential characteristics of the fibers.The ATP'ase and succinic dehydrogenase (SDH) activities of fibers were determined using standard histochemical techniques. Seventy‐six percent of fibers in the red segment had the high ATP'ase and high succinic dehydrogenase activity typical of fast‐twitch‐red fibers. Other fibers in the red segment were typically fast‐twitch‐white (13%) or slow‐twitch‐red (11%). The average cross‐sectional area of red fibers was 2,104 m̈m2. Fibers in the white segment were mostly (84%) fast‐twitch‐white with intermediate ATP'ase activity and low to intermediate SDH activity. The remaining fibers in the white segment were histochemically typical of fast‐twitch‐red fibers. The average cross‐sectional area of white fibers was 5,109 m̈m2. Morphologically, red fibers had three times as many mitochondria as white fibers and a Z‐line thickness 38% greater than that of white fibers.Although fibers from the red segment were histochemically and morphologically different from fibers in the white segment, the isometric tension characteristics, i.e., contraction time, post‐tetanic potentiation and fatigueability, were very similar and were typical of fast‐twitch‐fatigueable preparations. Thus, histochemical and morphological characteristics of fibers in the sternomastoid muscle are not indicative of the mechanical properties of the fibers.
Morphogenesis of the truncus arteriosus of the chick embryo heart: Tissue reorganization during septation
Authors: Thompson Robert P. , Fitzharris Timothy P. 
Published: February 2005

AbstractSeptation of the truncus arteriosus of the normal chick embryo heart was surveyed systematically with the light microscope. Tissue from replicate samples at successive periods of development was sectioned within an arbitrary coordinate system based on positional reference points along the external surface of the heart. Correlation of several aspects of tissue morphology within this spatial and temporal reference‐frame yielded a new description of tissue associations and kinetics during septation.A stable complex of tissue structures appeared in the downstream, distal truncus at Stage 25 and persisted throughout the septation process. This complex consisted of (1) the cephalic margin of the myocardial sheath, and (2) the adjacent bifurcation of the vascular lumen, linked together by (3) the newly condensed Y‐shaped strap of cells forming the aorticopulmonary septum. The apparent motion of this septation‐complex toward the ventricle(s), the appearance within the thoracic cavity of the adjacent segments of the aortic arches, and measures of tissue length and width suggested that septation was accompanied, and perhaps initiated, by increased tension along the truncus.The truncal ridges remained upstream from the complex, with mesenchymal condensations beneath the endocardium differentiating into the definitive semilunar valves. Downstream from the bifurcation, mesenchyme in the aortic arch region condensed around the separate lumens to form the smooth muscular tunica media of the great arteries. The epicardium developed in a caudocephalic direction along the heart tube. Vagal innervation approached the heart cephalocaudally. Capillaries formed along the dividing truncus in both directions. Autoradiography following 3H‐thymidine labelling demonstrated reduced DNA synthetic activity in the cephalic margin of the myocardium and aorticopulmonary septum, compared with the associated loose mesenchyme.
Morphogenetic reaggregation and luteinization of mouse preantral follicle cells
Authors: Nicosia Santo V. , Tojo Ryutaro 
Published: February 2005

AbstractSmall (60‐90 μm) and large (100‐130 μm) preantral follicles were isolated from adult mouse ovaries by a collagenase‐dissection technique. These follicles were composed of resting oocytes surrounded either by granulosa cells, only, or by granulosa and undifferentiated theca cells. Further enzymatic dissociation of primary follicles yielded monodisperse cells characterized by abundant rough endoplasmic reticulum, microfilament‐rich pseudopodia and only scant lipid droplets. These cells reaggregated, when explanted in stationary culture, forming epithelial cords and structures macroscopically reminiscent of native ovarian follicles. Anticipated association of follicular cells in epithelial‐like monolayers was rare (≤ 10% of all cultured cells). Formation and growth of both follicle‐like (FLS) and cord‐like (CLS) structures occurred within 24 hours of culture, continued for 14 days, and was inhibited by cytochalasin B, but not by neuraminidase. FLS and CLS, as well as cell monolayers, underwent luteinization, as indicated by the presence in the culture medium of radioimmunoassayable progesterone and by frequent cytological features suggestive of active steroidogenesis. The present report indicates that (a) specific cell affinities exist among immature follicular cells which may play a role in folliculogenesis; and (b) follicular cells are endowed, from their early developmental stages with intrinsic steroidogenic capabilities which become pheno‐typically expressed after escape from the intraovarian environment.
Differentiation of myoepithelial cells in the developing rat sublingual gland
Authors: Redman Robert S. , Ball William D. 
Published: February 2005

AbstractSublingual glands of rats were prepared for light and electron microscopy and for the histochemical demonstration of myofibrils and alkaline phosphatase (AkPase) activity. Through 17 days in utero, the epithelial cells of the glandular rudiment are relatively undifferentiated. At 18 days, the inner cells of the terminal buds begin to assemble around a lumen and accumulate secretory granules, while the outer cells flatten and form long processes. At 19 days, many of the outer cells have dilated cisternae of rough endoplasmic reticulum engorged with finely granular material. At 20 days, some of the outer cells have thin bands of microfilaments in their processes, suggesting that they are differentiating into myoepithelial cells (MEC). Though the secretory cells are almost mature at birth, only a few of the MEC have myofibrils detected with an actomyosin reaction, and AkPase activity is very weak. Progressive increases in AkPase activity and in myofibril size and number continue until the acini and intercalated ducts are fully invested with mature MEC at about 14 days after birth. Thus, the MEC and secretory cells begin to differentiate at the same time, but the MEC subsequently differentiate asynchronously with the secretory cells and with each other. Although the sublingual MEC are only partly differentiated in the newborn rat, their overall development occurs somewhat more rapidly than in the adjacent submandibular gland.
Fetal and neonatal rat pancreas in organ culture: Age‐related effects of corticosterone on the development of the islet cells
Authors: McEvoy Robert C. 
Published: February 2005

AbstractFetal (18 days postcoitum) and neonatal (3‐day) pancreatic explants were grown in organ culture with or without supplementation with corticosterone (0.1 μg/ml). After 0, 4, and 8 days of culture, the specific hormone‐positive, islet cell volumes were determined by the use of immunocytochemical and morphometric methods. The insulin, glucagon, and somatostatin contents of the explants were estimated by radioimmunoassays. In the fetal explants, all of the islet cell populations increased in volume and the content of each of the hormones increased over an 8‐day period of culture. Supplementation with corticosterone resulted in a restriction of the increases of the alpha and delta cell volumes and in the somatostatin content of the explants. In the neonatal explants, the volumes of the alpha and delta cells and the glucagon and somatostatin contents decreased over a 4‐day culture period. The presence of corticosterone in the culture medium preserved these cells and their hormone content. Co‐culture of 18‐day fetal and 3‐day neonatal pancreata in control medium for 8 days resulted in a significant decrease in the content of all three of the islet hormones in the fetal explants. These results suggest that a substance harmful to the islet cells is released from the degenerating acinar cells. Thus, the effects of the steroid on the islets may be mediated through its effects on the acinar tissue.
The stem‐cell zone of the small intestinal epithelium. III. Evidence from columnar, enteroendocrine, and mucous cells in the adult mouse
Authors: Bjerknes Matthew , Cheng Hazel 
Published: February 2005

AbstractIn the first two articles of this series we demonstrated restriction of Paneth cell formation to positions 5 and above. Restriction was independent of the Paneth cell population‐density gradient in the crypt base. We concluded that our results were consistent with the presence in the adult of a stem‐cell zone in positions 1–4 in which stem cells received no inducement to differentiate. To further test the stem‐cell zone hypothesis we determined the site of stem‐cell differentiation along mucous, enteroendocrine, and columnar cell lines using radioautography with 3H‐thymidine, as a label.One hour after injection of 3H‐thymidine, labeled mucous cells were not observed below position 5. Only later did they appear in lower positions and not until 4 days after injection were they observed in position 1. Labeled enteroendocrine cells first appeared above, and then were seen in the top of, and finally in the middle and bottom of the Paneth cell distribution. Thirty hours after injection there were two populations of labeled columnar cells in the crypt base, a heavily labeled population and a lightly labeled one. At this time interval the heavily labeled columnar cells were only observed in position 5 and above, but they appeared in position 1–4 by 66 hours after injection. The above evidence led us to conclude that all differentiated offspring of the common epithelial stem cell originate in positions 5 and above. Most columnar, mucous, and enteroendocrine cells originating in positions 5 and above migrate upward. However, some of these cells migrate down. All differentiated cells found in positions 1–4 migrated down from their origin in position 5 or above. We also found that only stem cells proliferate in positions 1–4. We concluded that in the adult, there is a stem‐cell zone in positions 1–4 where stem cells are not induced to differentiate and persist as stem cells throughout life.
Structural response of adult rat sertoli cells to peritubular fibroblasts in vitro
Authors: Cameron Don F. , Markwald R. R. 
Published: February 2005

AbstractSertoli cells were harvested from sexually mature rats and maintained in vitro for up to ten days (Sertoli cell‐enriched cultures) or co‐cultured with rat peritubular fibroblasts. Cultures were examined by differential light microscopy and by scanning or transmission electron microscopy.The presence of peritubular fibroblasts in co‐culture greatly enhanced plating efficiency and viability of adult Sertoli cells. Sertoli cell aggregates preferentially adhered to peritubular cells, and by ten days had flattened and spread across these cells. Sertoli cells retained their characteristic ultrastructural features. Early in co‐culture a collagen‐like extracellular material was seen bridging Sertoli and peritubular cells, and its appearance was coincident with the presence of swollen rough endoplasmic reticulum in peritubular cells. Interperitubular cell spaces became engorged with a fibrillar material morphologically similar to the basal lamina of the seminiferous tubule wall. In the absence of peritubular cells, in culture medium “conditioned” by prior incubation with peritubular cells but not containing them, or when cultured with other fibroblastic cells, plating efficiency was low; Sertoli cells never flattened and cell ultrastructure progressively degenerated. The results indicate that peritubular cells support adult Sertoh cells in culture, possibly via extracellular material derived from peritubular cells, and suggest that Sertoli cells have an inductive effect on peritubular cell secretory activity.
Unusual cytoplasmic bodies in chromaffin cells of the adrenal medulla of the viscacha (Lagostomus maximus maximus)
Authors: Piezzi Ramon S. , Lucero Roberto O. , Guzman Jorge A. 
Published: February 2005

AbstractComplex structures can be seen associated with large areas of endoplasmic reticulum of the chromaffin cells in the viscacha adrenal medulla. These structures are cylindrical in shape and are formed by chains of globular subunits. A central lumen is observed within which there are bodies resembling chromaffin granules. Parallel cisternae of the endoplasmic reticulum are arranged surrounding these bodies. The functional significance of these structures is unknown.
Tenotomy of the avian anterior latissimus dorsi muscle. II. Can regeneration from the stump occur in the pigeon?
Authors: Hikida Robert S. 
Published: February 2005

AbstractBecause the chick's anterior latissimus dorsi muscle (ALD) regenerates a fast‐twitch muscular connection after tenotomy, the pigeon's ALD was tenotomized, either at the origin or through the muscle 0.5 cm from the origin, to determine whether this muscle behaves similarly to the chick muscle. These procedures were compared in pigeons operated upon at 7 weeks, versus 5 to 9 months of age. The pigeon's ALD did not regenerate a new connection, and other differences were observed between the pigeon and chick ALD. The pigeon ALD has only a single slow muscle‐fiber type, has fewer fast fibers, and transforms to a fast‐twitch muscle more readily than the chick ALD after tenotomy. The transformation of muscle fiber types occurred more readily in the older pigeons than those tenotomized at 7 weeks of age. Tenotomy induced morphological alterations of the muscle fiber structure in all of the pigeons, which is in contrast to the absence of changes in the tenotomized chick ALD. Therefore the pigeon and chick ALD respond completely differently to tenotomy.
Topochemical aspects of nucleic‐acid and protein metabolism within the neuron‐neuroglia unit of the hypothalamic supraoptic nucleus
Authors: Pevzner Leonid 
Published: February 2005

AbstractThe RNA and both the total and basic protein content of individual cells were determined by cytospectrophotometry in neurons and perineuronal oligodendroglia of the hypothalamic supraoptic nucleus in rats subjected to various stresses, as well as in ground squirrels during natural hibernation. Barbiturate narcosis and deep cooling, which induced a decrease in body temperature in rats and hibernation in squirrels, caused a marked decrease of all macromolecular constituents in neurons. A similar decrease was found in the perineuronal oligodendroglia in rats, but an increase was observed in ground squirrels. After cessation of cooling, while the body temperature of the animals returned to normal, the neurons, but not the oligodendroglia, of rats showed a significant accumulation of RNA, while RNA accumulated in both neurons and perineuronal oligodendroglia in ground squirrels.Milder cooling of rats, which did not lower their body temperature, induced reciprocal changes in basic‐protein content in neuronal and glial cell nuclei, with the accumulation of protein occurring initially in neurons, and subsequently in glia. When cold adaptation was accomplished, the basic protein content of neurons and glial cells returned to the control level.Four days after adrenalectomy in rats, the RNA content decreased in oligodendroglia but not in neurons of the supraoptic nucleus. This effect was completely abolished by daily injections of cortisol in the adrenalectomized animals.The data obtained indicate the existence of differences in metabolic responses to stress between neurons and glial cells of the supraoptic nucleus of the hypothalamus.
Kidney of a juvenile okapi, Okapia johnstoni
Authors: Maluf N. S. R. 
Published: February 2005

AbstractThe kidney of the okapi is of the medullary crest type and is divided transversely into six lobes by encroachments of cortex into medulla. These lobes are demarcated externally by furrows. The collecting ducts open at the apex of the truncated medullary crest. The pelvic part of the kidney, or pars pelvina renis, is the entire inner medulla and is the only part exposed to the pelvic urine. The pelvis has 10 interlobar vascular eminences and extends peripherally along‐side the interlobar vessels as 10 fornices. The vascular eminences are buttressed by 12 free‐edged semilunar eminences, which form pouches across 12 intervascular eminences. At each pole a vascular eminence supplies blood vessels to a dorsal and a ventral intervascular eminence.The extrahilar portion of the renal vein consists mainly of a thick coat of longitudinal muscle. In the renal sinus this heavy muscular coat is absent. The tributaries of this vein open via conspicuous nonmuscular valves.The cortex is about 85% of the renal mass and has about 2.89 × 106 glomeruli, which form 4.85% of the cortical mass. The filtering surface of a glomerulus is 0.088 mm2, making the total filtering surface of one kidney 0.219 m2. The number of glomeruli per kidney falls into the line which relates number of glomeruli to adult body weight from mouse to elephant and is expressed by log N = 0.59 log W + 3.2 or by N = 1.585W0.59 where N is number of glomeruli in one kidney and W the adult body weight.
Identification of prolactin and growth hormone cells in the pars distalis of the California leaf‐nosed bat, Macrotus californicus
Authors: Richardson Bruce A. 
Published: February 2005

AbstractProlactin (PRL) and growth hormone (GH) cells were immunostained in the anterior pituitary lobe of the California leaf‐nosed bat with antisera against rat PRL and GH by the unlabeled immunoperoxidase technique. The PRL antiserum reacts with a cell that is carmoisinophilic and pleomorphic and occurs in small groups within the ventro‐, dorsocentral, and posteriolateral regions of the pars distalis. The cells that stain with the anti‐GH serum are orangeophilic, smaller than the PRL cells, and randomly scattered throughout the pars distalis, singly or in palisades near capillaries. Morphometric analysis of the immunoreactive PRL and GH cells revealed an inverse relationship between these two cell types.
Dedifferentiation of iris epithelium during lens regeneration in newt larvae
Authors: Reyer Randall W. 
Published: February 2005

AbstractEarly stages in lens regeneration from the pigmented epithelium of the dorsal iris were studied in larval Notophthaimus viridescens by means of transmission electron microscopy. Normal iris epithelium is composed of two layers of low cuboidal cells, packed with melanosomes and surrounded by a basal lamina. Scattered desmosomes attach adjacent cells. Following lens removal, the intercellular spaces enlarge and the epithelial cells increase in size. Some irregular microvilli from these cells extend into the intercellular spaces. Macrophages invade the iris epithelium and phagocytize melanosomes discharged from the pigmented cells. These invading macrophages have numerous microprojections and are often separated from the surface by a very thin layer of iris epithelial cell cytoplasm. In the iris cells, nucleoli become more prominent and granular, polyribosomes increase greatly in number, melanosomes gradually disappear, mitochondria become more numerous, and mitotic activity is greatly augmented. Fine cell processes of adjacent cells interdigitate near the external surface, where numerous micropinocytotic vesicles can be seen. Over the external surface, the basal lamina may be disrupted or duplicated in places where pseudopodia project from iris cells or a macrophage has entered an intercellular space. It is lacking on the lumenal surface. Sloughed membranes are often found in these intercellular spaces.
Degeneration of mouse digital corpuscles
Authors: Idé Chizuka 
Published: February 2005

AbstractThe sequential changes of the morphology and the histochemically demonstrated, nonspecific cholinesterase (ChE) activity of the denervated digital corpuscle (Meissner corpuscle) of the mouse were observed by light and electron microscopy for 6 months after transection of the sciatic nerve. A fragment of the sciatic nerve, approximately 1 cm long, was removed from the distal stump to prevent reinnervation. Within one day following nerve division, the axon terminals began to manifest degenerative changes; the axoplasm became electronopaque and some mitochondria became disorganized. The lamellar cell processes (lamellae) also exhibited atrophic changes; they became thinner and more electron opaque. The lamellar cell body became smaller due to a decreased amount of cytoplasm and contained few organelles except for some free ribosomes. These changes advanced with time. Around 4–6 months after denervation, the corpuscle was small, consisting of a few thin, shrunken, atrophic lamellar cells. The ChE activity persisted and could be demonstrated in the interlamellar spaces, but its intensity decreased with time so that the corpuscle was hardly identifiable by light microscope histochemistry around 4–6 months after denervation. During this time, the precipitates of the reaction product were scattered as small particles throughout the interlamellar spaces. The enzyme activity in the cisternae of the rough endoplasmic reticulum and the nuclear envelope of the lamellar cell body was no longer demonstrable 5 days or less after denervation. These findings indicate that the lamellar cell is dependent on the axon terminal to maintain its normal morphology and the function of ChE synthesis.
Response of tanycytes to aging in the median eminence of the rat
Authors: Brawer James R. , Walsh Raymond J. 
Published: February 2005

AbstractAge‐related changes in tanycytes of the median eminence were observed at both the light and electron microscopic level in male and female rats at ages 4 weeks to 14 months. The most obvious changes involved a marked progressive increase in number and size of droplets identified histochemically as neutral lipid and the development of complex degenerate bodies in the perivascular contact zone. These degenerate bodies consisted of large multiple complexes of myelin figures containing intercalated channels and pools of electron‐dense material. They often occurred interspersed among large lipid droplets. The degenerate bodies (myelin figure complexes) and associated lipid droplets occupied much of the contact zone in the older animals. Evidence of axonal degeneration and tanycytic phagocytosis of deteriorating neural elements was also present. These age‐related changes occurred independent of sex and were not affected by gonadectomy. This tanycyte response to aging in the median eminence is very similar to the response of neurohypophysial pituicytes to axonal degeneration, suggesting a phagocytic glial role for tanycytes.