bluuebunny/crossref_metadata_2025_split huggingface dataset:
A freeze‐fracture study of the maturation of synapses in the anteroventral cochlear nucleus of the developing rat
Authors: Mattox Douglas E. , Neises Gabrielle R. , Gulley Robert L. 
Published: February 2005

AbstractThe freeze‐fracture technique was used to study the maturation of the postsynaptic membrane of spherical cells of the anteroventral cochlear nucleus (AVCN) of the developing rat brain. Observations were made at 2‐day intervals from birth to 16 days of age. At all ages, the external leaflet (E‐face) of the spherical cell membrane has aggregates of particles opposite presynaptic active zones. From birth to 6 days of age, these particle aggregates were found only on dendritic processes, not on the cell body. At 8 days of age, the aggregates were found on small somatic appendages and on the cell body adjacent to somatic appendages. In animals from 10 to 12 days of age, particle aggregates became increasingly common on the cell body. Morphometric analysis demonstrated a decrease in size but not packing density of the particles in the aggregates. These changes in the location and size of the aggregates correspond to the location of asymmetrical synapses seen in thin section material at these same time intervals (Neises et al., 1982). At 14 days the fracture plane no longer followed the postsynaptic membrane at the active zone; instead it shifted to the presynaptic membrane and the postsynaptic specilizations were rarely seen. This fracture pattern is typical of adult animals.
The technique of heart plastination
Authors: Tiedemann K. , Hagens G. V. 
Published: February 2005

AbstractPlastinated hearts are natural specimens, preserved in a firm of flexible state, which thus can be grasped in the hand. They are fixed in a dilated state. Their tissue water and lipids are replaced by polymerized synthetic resins or elastomers. The final specimens show doubly injected coronary vessels, opened atria and ventricles, thus exhibiting all finer external and internal details. The procedure described consists of the removal of the heart; intermediate storage facilities; dilatation with water under hydrostatic pressure; color injection of the coronary vessels; fixation; dehydration in acetone under hydrostatic pressure; forced impregnation in a vacuum chamber; and hardening with aftercare. Technical variations and pitfalls are discussed, as well as the required equipment.
Recent structure‐function relationships in normal and injured mammalian kidneys
Authors: Bulger Ruth Ellen , Dobyan Dennis C. 
Published: February 2005

AbstractRecent investigations have been aimed at understanding the ultrastructural‐functional relationships within the kidney at organ, tubule, subcellular, and molecular levels. This has led to a redefinition and more precise segmentation of the renal tubule. For example, the connecting piece between distal tubule and collecting system has now been established.The use of immunocytochemical techniques, such as fluorescence, ferritin‐ or peroxidase‐labelled immunoglobulin methods, has made it possible to identify proteins in the kidney especially in renal corpuscles. Two major noncollagenous glycoproteins, fibronectin and laminin, have now been identified in the glomerulus. The glycosaminoglycan, heparan sulfate, has been localized to the glomerular basement membrane and is thought to play an important role in charge perm‐selectivity during glomerular filtration. Subtle changes in glomerular podocyte or endothelial cell structure are postulated by some to play a role in the pathogenesis of acute renal failure. The role of the mesangial cell in glomerular function is being studied in situ in homogeneous cell populations. These cells are capable of prostaglandin production and can contract in response to hormonal stimulation.The intimate positioning of short‐ and long‐looped nephrons in the renal medulla and the unique nature of the pelvic epithelium correlates well with the purported role of urea recycling in the urinary concentrating mechanism. Determination of elemental concentration of soluble substances in various renal cell and extracellular compartments have been made using freeze‐hydrated and freeze‐dried cryosections of kidney tissue.The medullary and cortical ascending thick limbs of the distal tubule are morphologically and functionally distinct regions. Their response to hormonal stimulation and their enzymatic activities are quite different. Morphological studies of the collecting duct have provided new insight into the role this segment of the uriniferous tubule plays in fluid and electrolyte transport and urinary acidification.
Morphological and morphometric changes in the ovaries of white‐footed mice (Peromyscus leucopus) following exposure to long or short photoperiod
Authors: Spanel‐Borowski Katharina , Petterborg Larry J. , Reiter Russel J. 
Published: February 2005

AbstractTwo experiments were carried out with a total of 36 white‐footed mice (Peromyscus leucopus) exposed to either long (LP) or short (SP) photoperiod for six weeks. Ovaries and uteri were weighed. Serial sections of the ovaries were processed for light microscopy. The total number of the interstitial gland cells, preantral and antral follicles with early and advanced stages of atresia as well as corpora lutea, was determined.Uteri from LP mice weighed significantly more than those from SP mice in both experiments. In contrast, the weight of ovaries from LP and SP animals only differed significantly in one experiment; this experiment also produced no obvious changes in the total number of corpora lutea. While interstitial gland cells of LP ovaries were hypertrophic and appeared mature, the interstitial gland cells of SP ovaries were of the degenerating cell type. The total number of follicles as well as their mean follicular diameters were higher in LP animals in comparison with SP animals. In addition, the percentage of antral follicles were increased and there were fewer signs of advanced stages of atresia in the LP group. It is suggested that the changes of the interstitial gland cell morphology combined with alterations of follicular growth during LP or SP appear to support intensified follicular growth.
Extracts of rat amniotic fluid contain a potent inducer of intestinal crypt formation
Authors: Calvert R. , Lehoux J.‐G. , Arsenault P. , Ménard D. 
Published: February 2005

AbstractThe effect of acid, basic, and organic extracts from Long Evans rat amniotic fluid (RAF) and from Swiss ICR mouse amniotic fluid (MAF) was studied on 15‐day fetal mouse duodenal mucosa in organ culture. Amniotic fluids (20 ml) were lyophilized and extracted (1) with CHCl3:MeOH and the organic phase was evaporated; then (2), the residue was acidified with a solution of 0.1 N HCl in 10% acetic acid and the liquid phase was lyophilized; finally (3), 0.01 M NH4OH was added to the residue and the liquid phase was lyophilized. The product of each extraction was added to 20 ml of Trowell T8 medium. Acid and basic extracts of RAF and MAF have no effect on the formation of duodenal villi and crypts after 48 hours of culture. With the organic extract of MAF, small villi are present after 48 hours of culture and absorptive cells are poorly differentiated. With the organic extract of RAF, well‐developed villi have differentiated after 48 hours of culture; moreover, crypts are present at the same stage and Paneth cells are identified within these crypts. During the 8–10 hour period, the explants cultured with the Trowell T8 medium supplemented with RAF or MAF organic extracts show a 35% increase in 3H‐thymidine incorporation over the controls cultured with Trowell T8 medium alone. These results indicate that organic extracts from MAF and RAF are able to promote villus formation in undifferentiated explants from 15‐day fetal mouse duodenum in organ culture. Furthermore, RAF organic extract contains a factor that can induce the formation of duodenal crypts and the differentiation of Paneth cells in culture at least 2 days before their normal appearance.
Uterine simple and complex nuclear bodies are separate structural entities
Authors: Padykula Helen A. , Pockwinse Shirwin M. 
Published: February 2005

AbstractIn rat uterine luminal epithelial cells, nuclear bodies occur in the euchromatin in varying numbers in relation to the nuclear concentration of the estrogen receptor (Clark et al., 1978; Padykula et al., 1981, 1982). This functional responsiveness indicates that nuclear bodies may be useful indicators of the degree of cellular estrogenization. Because these filamentous bodies vary in size (200–1200 nm), shape, and composition, quantitative analysis of frequency of their occurrence has been difficult. A fundamental division into 2 categories can be made by the following criteria: 1) simple nuclear bodies (200–500 nm) consisting of a protein mesh of microfilaments, and 2) complex nuclear bodies (200–1200 nm) composed of an outer filamentous protein capsule enclosing a lucent core that may contain granules. Previous quantitative analyses at the electron microscopic level has excluded “simple bodies” because they might actually be ultrathin sections through the filamentous capsule of complex bodies (Le Goascogne and Baulieu, 1977; Clark et al., 1978). To resolve this sampling problem, we have performed serial ultrathin section analysis of nuclear bodies in hyperestrogenized luminal epithelial cells. Ultrastructural evidence presented here demonstrates that simple and complex nuclear bodies are anatomically separate entities. Ultrathin sections through the capsule of complex nuclear bodies will be misidentified as profiles of simple bodies during quantitative analysis. This anatomic distinctness of simple and complex nuclear bodies correlates with their differing responses to estrogenic stimulation and withdrawal (Fitzgerald and Padykula, pp. 131–141, this volume). Thus the existence of these two major categories should be taken into consideration during quantitative analyses.
Differing functional responses of simple and complex nuclear bodies in uterine luminal epithelial cells following estrogenic stimuli
Authors: Fitzgerald Maryellen , Padykula Helen A. 
Published: February 2005

AbstractA single injection of estradiol or the antiestrogen, nafoxidine, into immature female rats results in a striking divergence in the frequency of observation of nuclear bodies in uterine luminal epithelial cells (Padykula et al., 1981). During the 72 hour period after a single injection of nafoxidine (estrogen antagonist with agonist effects), progressive cellular hypertrophy occurs and is accompanied by a linear increase in the total number of nuclear body profiles (TNB). Conversely, the 72 hour period after a single injection of estradiol is marked by cellular catabolism and a linear decrease in TNB. Our recent demonstration that the population of nuclear bodies consists of two major structural types, simple nuclear bodies (SNB), and complex nuclear bodies (CNB) (Padykula and Pockwinse, pp. 119–130, this volume), permits separation and analysis of the original TNB data in terms of the functional responses of SNB or CNB.During the 72 hour period after injection of nafoxidine, the luminal epithelial cells remain in an anabolic state because the nuclear concentration of estrogen receptor and RNA polymerase activity are elevated. Separate quantitative analysis of the complex and simple nuclear bodies demonstrates two distinct functional responses: (1) a linear increases in the frequency of CNB, and 2) a relatively constant frequency of SNB. Since the complex bodies do not increase in diameter during this period, the increase in the frequency of TNB may arise from an increase in the actual number of CNB per nucleus during cellular hypertrophy.Conversely, a single injection of estradiol results in a relatively short elevation of nuclear estrogen receptor concentration and RNA polymerase activity which returns by 24 hour to the control level. This brief estrogenic stimulation is reflected by a linear decrease in the frequency of TNB and a linear decrease in the frequency of SNB. The frequency of CNB decreases suddenly between 4 and 12 hours and levels off thereafter. The steady decrease in the frequency of observation of nuclear bodies during catabolism may represent a decrease in the actual number of SNB and CNB per nucleus rather than a reduction in their size.This study provides quantitative evidence that simple and complex nuclear bodies are functionally separate entities. Also, some evidence suggests that simple nuclear bodies may be the precursors of complex nuclear bodies.
Vicinal glycol‐staining identifies secondary granules in human normal and chédiak‐higashi neutrophils
Authors: Fittschen Claus , Parmley Richard T. , Austin Ronald L. , Crist William M. 
Published: February 2005

AbstractNeutrophil secondary granules contain large amounts of glycoprotein. We evaluated periodate‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) staining of these granules after α‐amylase digestion to assess their content of vicinal glycol‐containing glycoconjugates and the usefulness of this stain as a positive stain for secondary granules. Using this method, early stages of secondary granule genesis were observed prior to completion of primary granule genesis in myelocytes. Immature secondary granules appeared round to ovoid, but irregular in outline and demonstrated strong staining of the limiting membrane and matrix material. In mature granules, matrix staining was unaltered; however, membrane staining was decreased. Some immature primary granules in promyelocytes demonstrated strong PA‐TCH‐SP reactivity which was masked in mature primary granules of band and segmented neutrophils. The Golgi apparatus showed progressively increasing PA‐TCH‐SP reactivity toward its mature surface which was often convex in promyelocytes and myelocytes and concave in segmented neutrophils. The Chédiak‐Higashi secondary granules were cytochemically and morphologically similar to those of normal individuals and were not statistically decreased in number when compared to controls. They were only rarely observed contacting or fusing with giant granules which had consumed all primary granules leaving an easily detected population of secondary granules. Thus the α‐amylase‐PA‐TCH‐SP method demonstrates a large amount of unmasked vicinal glycol‐containing glycoconjugates in neutrophil secondary granules, which allows their differentiation from primary granules.
Spermatogenesis in the vasectomized monkey: Quantitative analysis
Authors: Hadley Mark A. , Dym Martin 
Published: February 2005

AbstractThe seminiferous epithelium in mature vasectomized Macaca fascicularis was examined quantitatively to assess spermatogenesis. Monkeys were bilaterally vasectomized and controls were bilaterally sham operated. At postoperative periods of 10 and 18 months, groups of monkeys were castrated and their testes prepared for morphologic analysis. Diameters were measured in 100 cross sections of seminiferous tubules from each animal. Numbers of spermatogonia (Ad and Ap), preleptotene spermatocytes, pachytene spermatocytes, and step 7 spermatids, relative to Sertoli cell nucleoli, were counted in stage VII tubules. Tubule diameter and germ cell numbers per Sertoli cell nucleoli were not altered by vasectomy. Our study demonstrates quantitatively that spermatogenesis in the monkey is not inhibited up to 18 months following vasectomy.
Quantitative assessment of neural development in human premolars
Authors: Johnsen D. C. , Harshbarger J. , Rymer H. D. 
Published: February 2005

AbstractThe number of nerve fibers entering a tooth gives an indication of the tooth's capacity to perform a sensory function. Nerve fiber development was quantitated from cross sections of the apical portions of 49 erupted human premolars at various stages of root development and in subjects up to 71 years of age. Neural development was incomplete in immature teeth, greatly variable in young mature teeth, and complete in older teeth. Myelinated axons changed in number but not in size during tooth development. There were significantly fewer myelinated axons in teeth with open and parallel apical foramina than in older teeth. Unmyelinated axons did not change significantly in number with development but fewer large axons were found in older teeth. The number of unmyelinated axons enclosed in a single boundary lamina tended to be lower in older teeth. As a physiologic correlate, threshold responses to electrical stimulation were also determined prior to premolar removal. Threshold stimulation decreased significantly with apical foramen maturation. A significant negative correlation was found between the threshold stimulus and the number of myelinated axons in fully developed teeth, but not in immature teeth.
Properties of soleus muscle Z‐lines and induced Z‐line analogs revealed by dissection with Ca2+‐activated neutral protease
Authors: Yamaguchi Mamoru , Robson Richard M. , Stromer Marvin H. , Cholvin Neal R. , Izumimoto Masatoshi 
Published: February 2005

AbstractRat soleus muscle Z‐lines and Z‐line anomalies induced by neostigmine methyl sulfate (NMS) and cat soleus muscle Z‐line and Z‐line anomalies induced by tentomy were examined by electron microscopy before and after dissection of muscle fibers with Ca2+‐activated neutral protease (CAF) to elucidate structural properties of Z‐lines and related Z‐line‐type structures. In both normal and treated muscles, interdigitation of thin (6–7 nm) filaments, which were continuous with I‐filaments (actin) from adjacent sarcomeres, was observed at the Z‐line in longitudinal section.Both neostigmine methyl sulfate and tenotomy treatments induced muscle atrophy associated with Z‐line degradation, streaming, and irregular distribution and accumulation of Z‐line material and Z‐rod formation. Tenotomized muscle also was characterized by the presence of N‐line‐like bands and I‐Z‐I brushes. CAF digestion removed the electron‐dense covering material from Z‐rods and revealed a backbone of actin filaments. The origin of Z‐rods, their structural similarity to Z‐lines in longitudinal and cross section, and their susceptibility to CAF indicate that Z‐rods are directly related to native Z‐lines and are probably lateral polymers of a basic Z‐line unit.The regular square net alignment (22 nm) of I‐filaments (actin) in cross sections of I‐Z‐I brushes which contain no N‐lines suggests that the I‐square net arrangement near the Z‐line is determined by Z‐filament‐actin filament interaction rather than by the N‐line or other factors.The results suggest that I‐filaments (actin) penetrate the mammalian Z‐line and are Z‐line constituents and that the width of Z‐lines and the length of Z‐rods are determined by the amount of overlap of actin filaments. The perpendicular periodicity of Z‐rods and the zigzag‐oblique arrowheadlike appearance seen in longitudinal section of Z‐lines are attributed to α‐actinin.
Pleiotropic effect of Tabby gene on epidermal growth factor‐containing cells of mouse submandibular gland
Authors: Blecher Stan R. , Debertin Manfred , Murphy Joanne S. 
Published: February 2005

AbstractThe influence of the Tabby gene on the submandibular gland of the mouse was assessed by comparing the mass of the gland, and its content of granular convoluted tubules, in prepubertal, pubertal, and adult Tabby mice and their wild type brother controls. The Tabby mice showed reduction in mass of the adult submandibular gland, delayed development of the granular convoluted tubules, and reduction in relative content of granular convoluted tubules. Epidermal growth factor (EGF) is released from the granular convoluted tubules of the mouse submandibular gland, and it is known to experimentally influence the devlopment of at least some of the structures that are affected by the Tabby gene. Accordingly, the question of a relationship between the Tabby gene and EGF is raised.
Ultrastructural observations on the shell membrane of the North American opossum (Didelphis virginiana)
Authors: Krause William J. , Cutts J. Harry 
Published: February 2005

AbstractEach developing opossum embryo is surrounded by a shell membrane which completely separates embryonic and maternal tissues. During the eighth and ninth prenatal days, the embryos together with their limiting shell membranes float freely within the uterine lumen, surrounded only by the secretions of the uterus. The shell membrane is transparent, nonelastic, tough, and capable of extreme deformation. It consists of a mat of interwoven fibers which vary in external diameter, are electron dense, and show no apparent substructure. The morphology and arrangement of component fibers are similar throughout the width of the shell membrane.
Endocytosis of cationized ferritin to vesicles in the Golgi region of the glomus cells dissociated from the adult rat carotid body
Authors: Grönblad Mats , Åkerman Karl Erik , Eränkö Olavi 
Published: February 2005

AbstractGlomus cells were dissociated from the carotid bodies of adult rats by enzymatic digestion with collagenase. The cells were then incubated at 37°C for 30 minutes to 3 hours in the continuous presence of cationized ferritin (CF) as a membrane marker and extracellular tracer to study the intracellular route of endocytosis in this cell type. After 30 minutes of incubation with CF, occasional solitary CF‐containing vesicles were observed at the cell periphery and also in the Golgi region. After 2–3 hours of incubation with CF, cell viability was still preserved and CF‐labeled vesicles were abundant in the Golgi region. CF particles were also seen in some vesicles having a dense core. The core of these labeled vesicles appeared to be less electron‐dense than that of typical secretory granules. It is suggested that the Golgi apparatus is involved in membrane recycling in glomus cells and that the membrane is then possibly further transported to an immature type of storage vesicle for reusage.
Tissue freeze‐drying with a closed drying tube stored in a freezer
Authors: Nelson Stanley R. , Wilkinson Harold L. , Walter Donnal C. 
Published: February 2005

AbstractA simple method of freeze‐drying tissue is described that does not require a continuously running vacuum pump. After the frozen tissue is positioned a few centimeters from the dessicant in a drying tube, a vacuum pump is attached briefly to lower the pressure in the drying tube. The drying tube is closed at a pressure of 5 × 10 −3 mm Hg or less, and the tube is stored in a freezer set at the desired temperature. Frog kidneys, 300‐400 mg, were dry in about 24 hr at −32°C and 48 hr at −40°C. Since the tissue is dried in individual drying tubes, many tissue samples can be dried at one time.