bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunocytochemical localization of glucagonlike and gastric inhibitory polypeptidelike peptides in the pancreatic islets and gastrointestinal tract
Authors: Smith Phillip H.
Published: February 2005

The distribution of cells displaying glucagonlike or gastric inhibitory polypeptide (GIP)‐like immunoreactivity was examined in the pancreatic islets and gastrointestinal tracts of rats, dogs, and humans. A‐cells in the pancreatic islets in all three species were stained by antisera having regional specificity for pancreatic‐type glucagon, gut‐type glucagon (glicentin), or GIP. Oxyntic A‐cells of the gastric mucosa in dogs and humans also were stained comparably by these three antisera. In contrast, the K‐ and L‐cells in the intestinal mucosa of those species were stained only by antisera capable of reacting with GIP or gut‐type glucagon, respectively. Tests of antibody specificity showed that the GIP antiserum did not cross‐react with either pancreaticor gut‐type glucagon. Likewise, the glucagon antisera showed no cross‐reactivity with GIP. Hence, these findings suggest that pancreatic and gastric A‐cells contain a peptide with GIP‐like immunoreactivity distinct from glucagon or glicentin per se. Although the exact basis of the GIP‐like immunostaining of A‐cells is unknown, it may be due to the presence of a glucagon precursor sharing certain amino‐acid sequences with GIP. This hypothesis is consistent with several recent investigations showing that the processing of proglucagon molecules differs between the A‐ and L‐cells.
Surface architecture of the mucosal epithelium of the cat trachea: II. Structure and dynamics of the membranous portion
Authors: Tandler Bernard , Sherman James M. , Boat Thomas F. , Wood Robert E.
Published: February 2005

Bronchoscopic examination of anesthetized cats revealed that the trachea is capable of considerable change in caliber via lateral expansion of the membranous trachea. The morphological basis for this expansile capacity was determined by correlated light microscopy and scanning and transmission electron microscopy. The organization of the membranous trachea differs from that of the cartilaginous trachea. The mucosa is arranged in a series of longitudinal folds that open like an accordion when stretched laterally. These fold are not random, but appear to depend on rows of nonciliated, microvillusrich cells that form flexure lines in the surface epithelium. The mitochondria in such cell have a condensed configuration, indicating a high level of oxidative metabolism and suggesting that they may participate in transport processes that modify the luminal contents. Goblet cells, which are relatively sparse in the membranous trachea, have mitochondria in which the prominence of matrix granules and degree of mucus storage are inversely related. Mitochondrial morphology allows goblet cells that have discharged their mucin content to be readily distinguished from the microvillus‐rich cells, even when their luminal surfaces lie outside the thickness of a section.
Is there a medial nucleus of the trapezoid body in humans?
Authors: Richter Ernst A. , Norris Barbara E. , Fullerton Barbara C. , Levine Robert A. , Kiang Nelson Y. S.
Published: February 2005

The medial nucleus of the trapezoid body (MNTB) appears to be a prominent auditory structure in many mammals. However, the presence of an MNTB in the human brain has not been clearly established. One of the most characteristic features of the cat MNTB is the presence of large somatic endings with multiple synaptic sites, the calyces of Held. We examined adult human brains at both light and electron microscopic levels and found neurons with unusually large endings in a location that is similar to that for the MNTB in other animals. Moreover, the sizes and shapes of some cells in this area are similar to the principal cells of the cat MNTB. These observations support the idea that humans have cells that resemble MNTB neurons in other species. It has been suggested that the cat MNTB may be involved in the generation of wave 3 of its brainstem auditory evoked potentials, so the presence of an MNTB in the human brain may have implications in interpreting brainstem potentials in man.
Cytochemical analysis of alkaline phosphatase and esterase activities and of lectin‐binding and anionic sites in rat and mouse Peyer's patch M cells
Authors: Owen R. L. , Bhalla D. K.
Published: February 2005

M cells in Peyer's patch follicle epithelium endocytose and transport luminal materials to intraepithelial lymphocytes. We examined (1) enzymatic characteristics of the epithelium covering mouse and rat Peyer's patches by using cytochemical techniques, (2) distribution of lectin‐binding sites by peroxidase‐labeled lectins, and (3) anionic site distribution by using cationized ferritin to develop a profile of M cell surface properties. Alkaline phosphatase activity resulted in deposits of dense reaction product over follicle surfaces but was markedly reduced over M cells, unlike esterase which formed equivalent or greater product over M cells. Concanavalin A, ricinus communis agglutinin, wheat germ agglutinin and peanut agglutinin reacted equally with M cells and with surrounding enterocytes over follicle surfaces. Cationized ferritin distributed in a random fashion along microvillus membranes of both M cells and enterocytes, indicating equivalent anionic site distribution. Staining for alkaline phosphatase activity provides a new approach for distinguishing M cells from enterocytes at the light microscopic level. Identical binding of lectins indicates that M cells and enterocytes share common glycoconjugates even though molecular groupings may differ. Lectin binding and anionic charge similarities of M cells and enterocytes may facilitate antigen sampling by M cells of particles and compounds that adhere to intestinal surfaces in non‐Peyer's patch areas.
The sertoli cell junctional complex: Structure and permeability to filipin in the neonatal and adult guinea pig
Authors: Pelletier R. ‐Marc , Friend Daniel S.
Published: February 2005

The development and maintenance of the Sertoli cell junctional complex were investigated in prepubertal and adult guinea pigs. To correlate the structure of the blood‐testis barrier with its permeability, the polyene antibiotic filipin (a cholesterol‐binding agent of low molecular weight: 570.70) was added to the fixative as a tracer visible in freeze‐fracture replicas. Discontinuous zonules, intermediate junctions (i.e., adhering fasciae) and gap junctions all proved permeable to filipin in the two age groups. Only the continuous occluding zonules characteristic of the adult guinea pig's testis were impermeable to the tracer.

In pubertal animals, the establishment of the blood‐testis barrier coincided with the completion of the junctional strands in occluding zonules. The formation of occluding zonules was similar in the newborn and the adult. In the adult, the Sertoli cell junctional complexes contained three types of cell junctions: occluding, adhering, and gap junctions. The sequence of occluding and adhering junctions from the base to the apex of the epithelium was the reverse of that demonstrated in most epithelia. The impermeable continuous occluding zonules at the base showed parallel patterns of uninterrupted junctional strands, whereas the permeable discontinuous zonules found higher in the epithelium showed a meandering pattern of broken strands.

Our observations indicate that (1) Sertoli cell junctional complexes form near the young germinal cells at the base of the seminiferous epithelium and break down near the older germinal cells toward the apex; (2) the various patterns and orientations of the junctional strands reflect, respectively, the different stages of disintegration of the occluding zonules and the conformation of the mature Sertoli cell to the irregular contours of the germinal cells; (3) there is no relationship between permeability and junctional strand orientation; and (4) the cellular contacts between Sertoli cells and germinal cells situated below the blood‐testis barrier may represent the early stages of formation of junctional elements which ultimately become incorporated into the Sertoli cell junctional complex.
The autoradiographic demonstration of estrogen binding in normal human cervix and vagina during the menstrual cycle, pregnacy, and the menopause
Authors: Gould Stanley F. , Shannon John M. , Cunha Gerald R.
Published: February 2005

Using the technique of in vitro steroid autoradiography, the localization and modulation of nuclear estrogen binding sites has been studied in normal human cervix and vagina during the menstrual cycle, pregnancy, and the menopause. Marked differences occur in nuclear estrogen binding between these two organs. Nuclear estrogen binding varies throughout the menstrual cycle in the vaginal epithelium, whereas vaginal stromal cells consistently exhibit nuclear estrogen binding throughout the cycle. In contrast, the cervical squamous and columnar epithelia show much less cyclic variability in nuclear estrogen binding sites. As in the vagina, the cervical stroma consistently binds estrogen. High levels of nuclear estrogen binding sites are found in the vagina of the postmenopausal patient, and lower levels of binding occur postpartum. The implications of these localizations, with special reference to the role of the cervical and vaginal stroma, are discussed.
Chronobiology: Anatomy in time
Authors: Pauly John E.
Published: February 2005

Chronobiology is that branch of science that objectively explos and quantifies mechanisms of biological time structure, including the important rhythmic manifestations of life. It is the study of biological rhythms. This paper introduces chronobiology and some of its vocabulary, principles, and techniques.

A circadian rhythm is a regularly repetitive, quantitative physiological change with a period of about 24 hr (20–28), but the spectrum of rhythms includes those with periods less than 20 hr (ultradian) and longer than 28 hr (infradian). These rhythms are ubiquitous among the eukaryotes, innate and endogenous; their periods are precisely controlled by synchronizers in the environment. Rhythms can be manipulated by altering their synchronizers or by introducing more dominant ones. When organisms are removed from their environment and placed in constant conditions, rhythms revert to their natural frequencies and free‐run. All of an organism's rhythms operate simultaneously, but their peaks and troughs do not necessarily occur at the same time.

There are rhythms in susceptibility to drugs; a fixed dose may have a therapeutic effect at one point along the 24 hr time scale and a harmful one at another. Knowledge of these rhythms can be important when designing experimental or treatment protocols and interpreting results. Examples are provided to show that single‐time‐point sampling can lead to erroneous results, unless biological periodicity is taken into consideration.
Chronobiology at the cellular and molecular levels: Models and mechanisms for circadian timekeeping
Authors: Edmunds Leland N.
Published: February 2005

This review considers cellular chronobiology and examines, at least in a superficial way, several classes of models and mechanisms that have been proposed for circadian rhythmicity and some of the experimental approaches that have appeared to be most productive. After a brief discussion of temporal organization and the metabolic, epigenetic, and circadian time domains, the general properties of circadian rhythms are enumerated. A survey of independent oscillations in isolated organs, tissues, and cells is followed by a review of selected circadian rhythms in eukaryotic microorganisms, with particular emphasis placed on the rhythm of cell division in the algal flagellate Euglena as a model system illustrating temporal differentiation. In the ensuing section, experimental approaches to circadian clock mechanisms are considered. The dissection of the clock by the use of chemical inhibitors is illustrated for the rhythm of bioluminescence in the marine dinoflagellate Gonyaulax and for the rhythm of photosynthetic capacity in the unicellular green alga Acetabularia. Alternatively, genetic analysis of circadian oscillators is considered in the green alga Chlamydomonas and in the bread mold Neurospora, both of which have yielded clock mutants and mutants having biochemical lesions that exhibit altered clock properties. On the basis of the evidence generated by these experimental approaches, several classes of biochemical and molecular models for circadian clocks have been proposed. These include strictly molecular models, feedback loop (network) models, transcriptional (tape‐reading) models, and membrane models; some of their key elements and predictions are discussed. Finally, a number of general unsolved problems at the cellular level are briefly mentioned: cell cycle interfaces, the evolution of circadian rhythmicity, the possibility of multiple cellular oscillators, chrono‐pharmacology and chronotherapy, and cell‐cycle clocks in development and aging.
Quo vadis basic and clinical chronobiology: Promise for health maintenance
Authors: Halberg Franz
Published: February 2005

Chronobiology is the eminently interdisciplinary science of interactions in time among metabolic, hormonal, and neuronal networks. It involves anatomy, biochemistry, microbiology, physiology, and pharmacology, at the molecular, intracellular, intercellular, and still higher levels of organization. The compounds coordinating a time structure‐–proteins, steroids, and amino‐acid derivatives–provide for the scheduling of interactions among membrane, cytoplasmic, and nuclear events in a network involving rhythmic enzyme reactions and other intracellular mechanisms. The integrated temporal features of the processes of induction, repression, transcription, and translation of gene expression remain to be mapped in relation to the available framework, consisting of the sequences of phospholipid and RNA labeling, DNA formation, and mitosis, to delineate a circadian cell cycle upon which further hormonal and neural coordination acts (Halberg et al., 1959a,b, 1979a). There is a need for communication over temporal as well as spatial distances among different specialized structures devoted, in individuals, to metabolism, growth, reproduction, and the ability to adjust, and, in species, to the capacity to adapt. For a better understanding at all levels of behavior in its broader sense of organization in time, chronobiology requires familiarity with temporal aspects of metabolism, hormones, and neurons. In other words, broadly trained, full‐time “general practitioners” of a chronobiology in its own right are needed.
The differentiation of the dermis in the laboratory mouse
Authors: Van Exan Robert J. , Hardy Margaret H.
Published: February 2005

The purpose of this study was to provide a comprehensive and sequential account of the differentiation of the dermis in one body region in a mammalian species. A histological, histochemical, and ultrastructural study was made of each cellular and matrix component of the dermis of the upper lip of the mouse during prenatal development. On the basis of these observations, the development of the dermis was divided into four phases: I) undifferentiated mesenchyme (12, 13 days), II) cell differentiation (14, 15 days), III) dynamic transition (16 days), and IV) matrix differentiation (beginning at 17 days). The first phase was marked by a decrease in the cell density but no change in the ultrastructure of the undifferentiated mesenchyme cells. The second phase began with the cytodifferentiation of the mesenchyme cells and was characterized by the appearance of new cell types in the dermis (immature fibroblasts, mast cells, myoblasts, and cells of indeterminate type). During phase III the dermis was undergoing rapid change. Fibroblasts became fully differentiated, mast cell density reached a sharp peak, there was a marked increase in the number of collagen fibrils in the dermal matrix and the first collagen fibers were observed, and changes occurred in the pattern of proteoglycan synthesis. Aggregations of vesicles appeared to be extruded from cytoplasmic blebs on the fibroblasts in large quantities at this time. Further differentiation of the dermal intercellular matrix occurred during the fourth phase, which continued after birth, as more collagen was laid down to form the connective tissue stroma.
Anatomy and vasculature of a minke whale heart
Authors: Ochrymowych Christina , Lambertsen Richard H.
Published: February 2005

The heart from a 4‐m‐long minke whale (Balaenoptera acutorostrata) was studied to determine the details of its anatomy and to consider cardiac adaptations to diving. The volume fraction (Vvc) of capillaries in the wall of the left ventricle was determined at different levels from base to apex and at different depths from epi‐ to endocardium using a light microscopic stereologic technique. Typical of cetaceans, this minke whale heart was distinctly flattened dorsoventrally. A moderator band, characteristic of ungulate hearts, spanned the right ventricle. The right and left atrioventricular valves were tricuspid and bicuspid, respectively. The right coronary artery supplied the dorsal and right lateral myocardium. The left coronary artery supplied the ventral and left lateral myocardium. An anastomosis between the dorsal and ventral interventricular arteries occurred in the dorsal interventricular groove. Stereologically, a decreasing transmural gradient in Vvc was identified between the epicardium and the subepicardium at 15 cm from the apex. Our results, however, did not reveal any significant deviations in the pattern of capillary distribution in the wall of the left ventricle between this baleen whale and terrestrial mammals. Measurements of the heart, great vessels, coronary vasculature, and ventricular walls are also given, and they suggest a physiologic and adaptive right ventricular hypertrophy. Based on these and other observations, we propose that the relatively great thickness of the right ventricle and the distinctive shape of the cetacean heart are adaptations to the hemodynamic changes and collapse of the thorax associated with apneic diving.
Functional anatomy of the peripheral olfactory system of the african lungfish Protopterus annectens owen: Macroscopic, microscopic, and morphometric aspects
Authors: Derivot Jacques H.
Published: February 2005

An anatomical functional study of the olfactory system of Protopterus annectens along the course of the primary olfactory neuron was made by means of macroscopic and microscopic methods on samples of specimens weighing from 3 to 1.250 gm. The olfactory organ, opening by anterior and posterior nostrils into the oral cavity, may be considered a macrosmatic fish type according to the repartition of receptor areas along parallel grooves and on the basis of its active irrigation mechanism. A morphometric study of Protopterus, using a set of seven specimens weighing from 4 to 350 gm, is compared with two morphometric studies on Silurid fishes and reveals some original features concerning the increase of the surface area of the receptor epithelium. The olfactory organ is meant to function in water; its isolation from the aerial environment is carried out by closing the apertures with edema linked to the hypothyroid and cholinergic crisis during the starvation stage; it represents an adaptation to the life in a special environment. This study does not support the assimilation of the posterior intrabuccal opening to a choana, nor the presence of a functional vomeronasal organ. The olfactory nerve shows a definite degree of organization, but it was not possible to recognize any vomeronasal nerve linked with the former. The histological organization of the bulbar relay is of a primitive type; it was impossible to locate an accessory olfactory bulb corresponding to a functional vomeronasal organ, the presence and the innervation of which by the nervus terminalis is discussed.
A light and electron microscopic study of osteodentin formation in the rat incisor after adriamycin administration
Authors: Karim Algernon C. , Eddy Ertrice L.
Published: February 2005

The effect of adriamycin (10 mg/kg body weight) on the rat incisor was investigated in 8‐day‐old animals at 9 days and 14 days after subcutaneous injection. The drug produced changes that were still present 14 days after administration. During this time osteodentin formation, which appeared to be the principal effect of the drug on the incisors, occurred to such an extent that in some regions of the teeth the pulp chamber was almost completely occluded. The formation of osteodentin began at the periphery of the pulp and gradually advanced towards the central region. Moreover, in some sections of the incisor the dentin layer was greatly reduced to a thin superficial layer, while osteodentin surrounded most of the pulp chamber. Cells that appeared to be differentiated pulp‐mesenchymal cells were found within as well as on the surface of the irregular osteodentin matrix. Since this drug has been used in the treatment of childhood osteosarcomas, the possibility of dental abnormalities developing in these children cannot be overlooked.
Ultrastructural localization of lectin receptors on the bone‐marrow sinusoidal endothelium of the rat
Authors: Pino Richard M.
Published: February 2005

The bone‐marrow

The hyphenation of bone‐marrow preceeding sinusoids or endothelium in this paper is in accordance with the style required by The American Journal of Anatomy. R.M.P

sinusoidal endothelium is a cellular bar‐rierthat separates developing blood cells in the extravascular space from the peripheral circulation. Mature blood elements enter the circulation via transendothelial migration pores. In the present study, monosaccharide constituents on the bone marrow endothelium were examined using lectin‐affinity cytochemistry. With lectin‐horseradish and lectin‐ferritin conjugates, mannosyl, N‐acetylglucosaminyl, galactosyl, N‐acetylgalactosaminyl, and sialic acid were localized to the luminal plasmalemma, bristle‐coated pits and diaphragmed fenestrae. These were conspicuously reduced on the abluminal plasmalemma. When the tissue was treated with biotinylated lectins followed by avidin‐ferritin, only a localization with wheat‐germ agglutinin (sialic acid; N‐acetylglucosaminyl) was observed. Pretreatment of the bone marrow with neuraminidase enabled the localization of the other monosaccharide components by the biotin‐avidin method. Accumulations of carbohydrate residues were identified near the endothelium subjacent to migrating cells. Fucosyl moieties marked by Ulex europaeus agglutinin (UEA) reagents on the endothelium were not present. All binding was abolished by incubation of tissue and lectin conjugates with specific hapten sugars. Labeling was also not present after Pronase E treatment, indicating that the identified monosac‐charides are components of glycoproteins rather than glycolipids. The possible function of endothelial‐surface glycoproteins as receptors for the surfaces of mature blood cells and their role in transmural migration are discussed.
Injury to nerves and the initiation of amphibian limb regeneration
Authors: Mescher Anthony L.
Published: February 2005

The possibility has been investigated that nerves, which promote mitotic activity during the growth phase of limb regeneration, may also release factors upon injury to stimulate the cellular events during the initiation of regeneration. These events have been compared in control, innervated limb stumps and in limbs denervated for various periods before amputation. Wound closure occurred in an essentially normal manner in limbs denervated at the time of amputation but frequently occurred at reduced rates or not at all in limb stumps denervated 5 days before amputation. Tissue loss and various degrees of morphological regression were seen in many of the predenervated limb stumps, including all of those denervated for 6 days or more before amputation. Evidence is presented which suggests that regression may result from a combination of the denervated state and disturbance to the limb ' vascular system. Limbs predenervated 2‐10 days before amputation were fixed 7 days after amputation and examined histologically. All limb stumps, including those involved in regression, showed tissue dissociation and cellular dedifferentiation. Autoradiography revealed that the dedifferentiation involved DNA synthesis in both denervated and innervated limbs. Seven days after amputation, DNA‐labeling indices in limb stumps predenervated 2 or 4 days were similar to those of control limbs, but labeling indices were significantly reduced in limbs predenervated 6 or more days. The results are assessed in light of the state of nerve degeneration in the limbs at the time of amputation and are discussed in terms of what is known regarding nerve‐derived growth‐promoting substances.
A radioautographic study of the incorporation of iron 55 by the ameloblasts in the zone of maturation of rat incisors
Authors: Karim A. , Warshawsky H.
Published: February 2005

This study was designed to study the time course of the incorporation of 55Fe into the ameloblasts of maturation in rat incisors. Male Sherman rats (100 ± 5 gm) were injected intravenously with 0.9 mCi of 55Fe and sacrificed in pairs by perfusion at various time intervals from 5 min to 7 days after injection. The incisors were demineralized in 4.13% disodium EDTA, postfixed in 1% osmium tetroxide in veronal acetate buffer, and embedded in Epon. Incisors from control rats injected with only physiological saline were treated in the same way. Sections from blocks of tissue in the zone of maturation were prepared for light microscope radioautographic observations. The greatest incorporation of iron occurred at 9 mm within the zone, at this site the ameloblasts contained few pigment granules. About 5 mm deeper into the zone the activity fell off to zero, as observed at 2.5 hr after injection of 55Fe. Between 1 day and 7 days after injection the 55Fe labeling was found over the cells containing many pigment granules, while the initial labeling over the cells within 9 mm of the zone had diminished. These data have shown that at any given time, from 30 min to 4 hr, the iron enters the maturation ameloblasts over a wide extent of the zone, reaching a maximum at about 9 mm from the onset of maturation. However, at longer times (1 day to 7 days) the labeling curve shifts and shows the greatest activity beyond 9 mm within the zone.
The development of the spleen in the Australian lungfish, Neoceratodus forsteri Krefft, with special reference to its relationship to the “gastro”‐enteric vasculature
Authors: Saito Hiroaki
Published: February 2005

The spleen of Neoceratodus forsteri Krefft grows in the shape of a “boomerang” on the left lateral‐dorsal‐right lateral part of the borderline between the foregut and the yolkgut. Development of the spleen follows the following stages: (1) appearance of the splenic primordium as a mesenchymal condensation in a limited portion of the region supplied by the third and fourth vitelline arteries on both sides, (2) development of the splenic sinuses within the primordium, (3) formation of the “gastric” and enteric splenic portal systems and (4) growth of the spleen along the anterior extremity of the spiral valve. The blood vascular dynamics of the foregut and the yolkgut are intimately involved with the formation of the spleen in this species. These processes were, therefore, compared with similar processes in other animals, and the characteristics of this organ common to vertebrates were investigated.
Histological and ultrastructural studies of secondary neurulation in mouse embryos
Authors: Schoenwolf Gary C.
Published: February 2005

The histological and ultrastructural features of secondary neurulation in C57BL/6 mouse embryos were examined as a first step in the analysis of how this process occurs in mammalian embryos. Secondary neurulation involves two major events in mouse embryos: (1) formation of the medullary rosette (9.5‐ to 10‐day embryos) or plate (11‐ to 12‐day embryos), and (2) cavitation. These two events occur simultaneously. The medullary rosette consists of elongated tail bud cells, radially arranged around a central lumen formed by cavitation. The secondary portion of the neural tube forms in 9.5‐ to 10‐day embryos by progressive enlargement of the central lumen and addition (by cell recruitment or mitosis) of tail bud cells to the rosette. The medullary plate likewise consists of elongated tail bud cells, but these cells do not surround a central cavity. Instead, cells of the medullary plate extend ventrad from the basal aspect of the dorsal surface ectoderm to a slit‐like cavity formed by cavitation. Formation of the secondary neural tube occurs in 11‐ to 12‐day embryos, principally by the recruitment of more lateral and ventral tail bud cells into the medullary plate. Free cells and cellular debris are frequently encountered in the forming lumen of the secondary neural tube, but cells exhibiting signs of necrosis were absent in cavitating regions. Numerous small intercellular junctions form at the inner (juxtaluminal) ends of tail bud cells as the medullary rosette or plate is forming and cavitation is occurring. These observations suggest that cavitation per se (i.e., formation of a lumen) during secondary neurulation is a relatively passive phenomenon, which results principally from neighboring cells becoming polarized apicobasally and incorporated into a primitive neuroepithelium. The latter constitutes the walls of the forming secondary neural tube.
Cartilage in the atlantic hagfish, Myxine glutinosa
Authors: Wright Glenda M. , Keeley Fred W. , Youson John H. , Babineau Donna L.
Published: February 2005

Light and electron microscopic observations and biochemical analysis of the lingual cartilages from the Atlantic hagfish, Myxine glutinosa, reveal two different types of cartilage, designated types 1 and 2, respectively. The anterior and medial lingual are type 1, while the posterior lingual cartilage is type 2. Chondrocytes in type 1 cartilage are similar to those found in other vertebrate cartilages. The presence within the Golgi elements of material that resembles a component of the extracellular matrix suggests the involvement of active chondrocytes in the synthesis of the matrix. The matrix of the type 1 cartilage contains fibrils arranged to form concentric lamellae in the territorial matrix and irregularly arranged, branched fibrils in the interterritorial matrix. Biochemical analysis of the type 1 cartilage reveals that it is composed primarily of a cyanogen bromide (CNBr)‐insoluble protein of unique composition that we have termed “myxinin.” Myxinin appears to be similar, but not identical, to lamprin. Type 2 cartilage bears no resemblance to any other known vertebrate cartilage. The principal cells are hypertrophied and are characterized by masses of cytoplasmic filaments. The appearance of the organelles in smaller nest cells suggests that nest cells are active in the production of some of the matrix, which consists primarily of collagen. Microfibrils and a basal lamina‐like material are also present. Biochemical analysis of the type 2 cartilage reveals that the CNBr‐insoluble material is different from myxinin. Comparisons of lamprey and hagfish cartilages prompt the concept that these two agnathans probably followed long‐independent evolutionary histories.
Effects of compound 48/80 on hepatic glycogen and glucose‐6‐phosphatase early in the diurnal cycle of the rat
Authors: Dimlich Ruth V. W. , Cardell Robert R.
Published: February 2005

The amount and distribution of glycogen as well as the activity of glucose‐6‐phosphatase (G‐6‐Pase) in the livers of rats were analyzed by biochemical and/or histochemical techniques. During the first 5 hr of the light cycle, livers of rats were sampled prior to and 30 min following an injection of compound 48/80 or Ringer's solution. Glycogen decreased significantly in response to sampling; however, treatment with compound 48/80 provoked an additional significant decrease in hepatic glycogen. These differences occurred irrespective of the time during the 5 hr that this was studied. The livers of the majority of the rats treated with compound 48/80 displayed a periportal distribution of glycogen, while those treated with Ringer's showed a more uniform pattern. Hepatic G‐6‐Pase activity was unchanged in either the Ringer's or compound 48/80 treated rats. These results indicated that (1) the significant glycogenolytic response occurs independently of the amount of glycogen present, (2) G‐6‐Pase activity is not affected within 30 min following the stimulation of glycogenolysis, (3) variation in glycogen patterns during depletion depends on the nature of the stimulus and/or degree of response, and (4) the amount of glycogen available for release is limited.
On the functional morphology of the human petrous bone
Authors: Doden E. , Halves R.
Published: February 2005

In this study the human petrous bone was investigated to find out whether and in what way it is adapted to mechanical stress by inner bone structure. Three normally formed petrous bones were cut in serial sections and examined by means of microradiography and circular polarized light with respect to mineralization, distribution of bone structure, and collagen fiber arrangement over the cross section. It has been shown that the human petrous bone can be divided morphologically into four different bony layers: (1) endosteal; (2) enchrondral; (3) inner periosteal layers, which together form the labyrinthine capsule and which are characterized by a higher level of mineralization and show no clear indication of bone remodeling; and (4) outer periosteal layer, in which numerous osteons indicate appositional and resorptional growth processes. The collagen fibers in the labyrinthine capsule are arranged in an irregular web‐like pattern, whereas in the outer periosteal layer they run predominantly parallel to the surfaces of the petrous bone, probably to minimize the mechanical stress in the form of a tension band. These results support the assumption that in the human petrous bone, the outer periosteal layer is adapted to resorb elastic deformation, whereas the brittle labyrinthine capsule is better adapted to the functions of an auditory and vestibular organ.
Fine structure of the glomerular basement membrane and immunolocalization of five basement membrane components to the lamina densa (basal lamina) and its extensions in both glomeruli and tubules of the rat kidney
Authors: Laurie G. W. , Leblond C. P. , Inoue S. , Martin G. R. , Chung A.
Published: February 2005

Electron microscopic immunostaining was used to examine the localization of type IV collagen, laminin, entactin, heparan sulfate proteoglycan, and fibronectin within the basement membranes of the rat kidney. In preliminary experiments, various methods of processing formaldehyde‐fixed kidney were compared using antilaminin antiserum and the indirect immunoperoxidase method. Little or no laminin immunostaining of the glomerular basement membrane was present in sections unless they had been frozen‐thawed; and even in this case, the immunostaining was light in comparison to that of basement membranes in adjacent tubules. However, when frozen‐thawed sections were treated with 0.5% sodium borohydride, immunostaining was then as strong in glomerular as in tubular basement membranes. Accordingly, this treatment was applied to frozen‐thawed sections before immunostaining for any of the substances under study.

Immunostaining of the glomerular basement membrane for each of the five substances was fairly uniform throughout the lamina densa (also called basal lamina), but uneven in the lamina lucida interna and externa (also called lamina rara interna and externa) in which stained bands extended from the lamina densa. Similarly in the basement membranes of tubules, immunostaining for the five substances was localized to the lamina densa and bands extending into the lamina lucida.

When the ultrastructure of the glomerular basement membrane was examined, three structures were found: (1) a network of 4‐nm‐thick “cords,” which seems to be the main component; the cords are closely packed in the lamina densa and more loosely arranged in the lamina lucida interna and externa; (2) straight, hollow 7–10‐nm‐thick structures referred to as “basotubules”; and (3) 3.5‐nm elements composed of minute paired rods, referred to as “double pegs.” The distribution of the cords, but not that of the other two structures, was related to the immunostaining pattern.

It is concluded that (1) to fully reveal the antigenicity of the glomerular basement membrane, frozen‐thawed sections must be treated with sodium borohydride prior to immunostaining, possibly because this basement membrane is more compact than the others; and (2) in both glomerular and tubular basement membranes, type IV collagen, laminin, entactin, heparan sulfate proteoglycan and fibronectin are colocalized in the lamina densa and its extensions to the laminae lucidae. Since the distribution of the cords corresponds to that of immunostaining, it is likely that the five substances are present within the cords.
The effect of age on lung structure in male BALB/cNNia inbred mice
Authors: Kawakami Masahiko , Paul J. Lawrence , Thurlbeck William M.
Published: February 2005

Morphometric examination using light, scanning electron, and transmission electron microscopy was performed on the lungs from 32 inbred male BALB/cNNia mice between 38 days and 28 months of age.

Between 38 days and 9 months of age the changes were primarily those of growth. Alveolar multiplication and total elastic‐fiber length appeared complete by 38 days of age. The major increase in the number of interalveolar pores occurred by 68 days, but there was a significant further increase from 68 days to 9 months of age. At 9 months, approximately 10% of the alveolar wall was formed by pores. Alveolar ducts, the cylindrical core of air central to alveolar mouths, increased more in diameter than length.

Between 9 and 28 months the changes were attributed to aging and were different from those reported in humans and other species. Lung volume, alveolar surface area, and total volume of alveolar wall increased with age; there was no change in mean linear intercept and volume proportion of alveolar and alveolar duct air. Total area of pores increased with age, but their number and area fraction of the alveolar wall did not change. No transmission electron microscopic changes were seen in the alveolar walls. We speculate that the morphometric differences between our animals and those studied in other reports may reflect the fact that our animals were specific‐pathogen—free animals and kept under protected circumstances.
Morphologic and cytochemical characteristics of amine‐containing globule leukocytes in rat tracheal epithelium
Authors: Pearsall Allan D. , Echt Robert , Ross Lawrence M. , Roth Robert A. , Dinerstein Robert J.
Published: February 2005

Amine‐containing cells in the tracheal epithelium are typically of the small‐granule type (diameter approximately 100 nm). However, in the rat, another amine‐containing cell type has been identified that possesses the amine‐handling features of the APUD‐series of cells (amine precursor uptake and decarboxylation) but not the ultrastructural characteristics. It has been postulated that these cells may be related to cutaneous melanocytes. In this study, fluorescent cells were present in the laryngeal and tracheal epithelial lining of adult Sprague‐Dawley rats following freeze‐drying and exposure to formaldehyde vapor (FIF or formaldehyde‐induced fluorescence). Microspectrofluorimetry revealed an emission maximum at 493 nm. The excitation maximum could not be calculated but appeared to be around or below 350 nm (to record spectra below requires the use of quartz optics). Yellow fluorescence also emanated from serotonin‐containing mast cells (excitation and emission maxima: 401/515 nm). Tracheal segments processed according to the aqueous formaldehyde (AFIF) technique, for the demonstration of 5‐hydroxytryptophan (5‐HTP) or serotonin (5‐HT), failed to identify fluorescent cells in the epithelial lining even though connective‐tissue mast cells were evident. Subsequent treatment of AFIF‐fixed sections with formaldehyde and HCl vapors (AFIF‐HCl) resulted in the formation of a fluorogenic compound within numerous cells in the tracheal lining (455/537 nm). This spectral shift and increase in intensity of fluorescence following acidification are characteristic for standards and/or cells that contain tryptamine, tryptophan, or peptides with NH2‐terminal tryptophan and are markedly different from microspectrofluorimetric data reported for the phenylethylamines or serotonin. It is therefore postulated that these cells contain a closely related β‐(3‐indolyl) ethylamine‐like compound, serotonin excluded.

The morphology of the fluorescent cells was similar when prepared according to the FIF or AFIF‐HCl techniques. Conjunctive staining, the examination of a single section first by fluorescence microscopy and subsequently by other histochemical and cytochemical methods, demonstrated that the fluorescent granules were also methylene blue, alcian blue, periodic‐acid Schiff, and ferricferricyanide positive. Subsequent correlative electron microscopic examination of Epon‐embedded AFIF‐HCl‐treated tracheal sections demonstrated that these amine‐containing cells were globule leukocytes.
Seasonal variations in pituitary LH‐gonadotropes of the hibernating bat Myotis lucifugus lucifugus: An immunohistochemical study
Authors: Anthony Edythe L. P. , Gustafson Alvar W.
Published: February 2005

Pituitary gonadotropes were identified throughout the year in the seasonally breeding, hibernating bat Myotis lucifugus lucifugus by means of light microscopic immunohistochemistry. In both male and female bats, these cells were immunoreactive with an antiserum directed to the β subunit of luteinizing hormone. Some gonadotropes were aggregated near a portion of the infundibular stalk which crosses the anterior lobe, while most were scattered singly in a uniform manner throughout the rest of the pars distalis. This cell population exhibited seasonal variations in both sexes. In males, the proportional volume of the pars distalis occupied by immunoreactive gonadotropes (volume fraction) was significantly reduced in late July, when plasma testosterone levels were approaching their seasonal peak. In females, the volume fraction declined in April, following ovulation, and remained low during pregnancy and lactation. The size and shape of gonadotropes appeared relatively constant throughout the annual reproductive cycle in male bats; the immunoreactive cells were irregular in shape, with cytoplasmic extensions insinuating between and often “cupping” other secretory cell types. In females, the gonadotropes resembled those of males throughout most of the year, except during pregnancy, when these cells became enlarged and ovoid. No evidence of involution was observed in these anterior pituitary cells in either males or females during hibernation.
The double cascade of lymphoid proliferation: Current challenges and problem areas
Authors: Nossal G. J. V.
Published: February 2005

Two largely but not entirely separate cascades of proliferation and differentiation are involved in immunity. First, processes that are mainly independent of the entry of antigen into the body generate the two types of lymphocytes, T cells and B cells. This lymphoneogenesis proceeds in the thymus and the bone marrow, respectively. It creates families and subfamilies of nondividing cells that do nothing but patrol the body until antigen enters. Each lymphocyte set represents a repertoire of recognition units preequipped with receptors for antigen, and each individual lymphocyte carries its own particular specificity as a result of a somatic rearrangement of genes. When an antigenic stimulus is given, the second and antigen‐dependent wave of proliferation and differentiation occurs. This involves clonal selection of particular lymphocytes within the repertoire with specificity for the antigen, and the generation of both immunologic effector cells and memory cells. This second cellular cascade takes place chiefly in the secondary lymphoid tissues, e.g., lymph nodes or spleen. The developing immune system learns to discriminate self from not‐self. The paper outlines the chief mechanisms operative in immunologic tolerance and also briefly addresses the fact that T lymphocytes must learn to “see” antigens in association with a “self” major‐histocompatibility‐complex antigen. Both proliferative cascades depend on intercellular interactions, but much more is known about those operative in antigen‐driven lymphocyte activation. Here there is a cyclical process in which antigen‐trapping cells stimulate helper/inducer T cells, which in turn stimulate cytotoxic/suppressor T cells or B cells. Some T‐cell products can augment the antigen‐trapping cells' inductive role. The structure of some of the molecules involved is rapidly being revealed by gene cloning and expression, but the anatomic basis of cell interactions within the lymphoid system is not being addressed as fully as it might be.
Ontogeny of primary lymphoid organs and lymphoid stem cells
Authors: Le Douarin Nicole M. , Dieterlen‐Lièvre Françoise , Oliver Peter D.
Published: February 2005

Cells of the immune system go through a series of important developmental steps that begin early in embryonic life and include, first, the various waves of hemopoietic‐cell production in the embryo and, second, the homing of these cells to the hemopoietic organs, which are the sites of hemopoiesis and lymphopoiesis in embryonic and adult life. The avian embryo is an important model for investigating these early steps; and this paper presents a comprehensive review of the work done on the early ontogeny of the avian immune system.
Early events in T lymphocyte genesis in the fetal thymus
Authors: Owen John J. T. , Jenkinson Eric J.
Published: February 2005

There is considerable uncertainty about the nature and level of maturation of the stem cells which colonize the thymus. Arguments are presented here which raise doubts about the claims that these cells have undergone substantial maturation along the T‐lineage pathway prior to migration to the thymus. Instead, emphasis is placed on the role of thymic stromal cells in T‐lymphocyte maturation. The heterogeneous nature of these cells is well established, but progress is described in analyzing the various cell types and their embryological origins. In particular, the expression of the major histocompatibility complex (MHC) antigens on thymic stromal cells might be relevant to the understanding of restriction and tolerance. The early phases of thymus lymphocyte differentiation are described; but no clear account of the generation of T‐cell subsets from immature cells can, as yet, be offered.