bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of the mammotrophs and gonadotrophs in the anterior pituitary gland of rats with protein‐calorie malnutrition
Authors: Herbert Damon C.
Published: February 2005

The structure of the anterior pituitary gland of rats with protein‐calorie malnutrition was studied at the light and electron microscopic levels. Male Sprague‐Dawley rats were fed a low‐protein diet from 20 to 50 days of age. The hypophyses from these animals, along with those from age‐matched controls, were then removed and fixed for light microscopic immunocytochemical analyses, using anti‐rat PRL or anti‐ovine LHβ serum, or for routine ultrastructural study.

The overall number of mammotrophs and gonadotrophs appeared to be unaffected by the deficiency in dietary protein. However, the nuclei, in both cell types, were significantly smaller in the malnourished rats. Cytoplasmic volume was also apparently less than in control rats, leading to the “crowding” of adjacent cell types. Additionally, in the malnourished rats, the mammotrophs assumed a less polygonal profile, while the gonadotrophs, which were more irregularly shaped in the central zone, rarely displayed the negative image of a Golgi complex. Ultrastructurally, the mammotrophs in the experimental rats had a less extensively developed granular endoplasmic reticulum and Golgi complex. The number of secretory granules was not different; however, their size was markedly less and their shape was round to ovoid, rather than pleomorphic. Two types of gonadotrophs were distinguished, based on the classification of Kurosumi et al. ('76). The type‐I cell (former “FSH” cell) had a smaller Golgi complex, less vesicular endoplasmic reticulum and smaller secretory granules. The major alteration in the type‐II gonadotroph (former “LH” cell) was the smaller size of the secretory granules.

The morphological changes found in this study support our previous physiological observations (Herbert, '80), which demonstrate that prolactin and gonadotrophin secretion are severely impaired in rats suffering from protein‐calorie malnutrition.
Relationship of intracerebral pituitary grafts to central neuropeptide systems
Authors: Knigge Karl M.
Published: February 2005

Variable amounts of pituitary tissue from neonatal or 30‐day‐old donor rats were implanted in the recessus triangularis or third ventricle of hypophysectomized male host rats. The pituitary tissue was implanted either immediately or 30 days after hypophysectomy of the host rat. Grafts from donors of either age were capable of maintaining a significant degree of testicular weight in one‐third of the implanted animals. Neonatal grafts were not capable of restoring testicular weight when implanted 30 days after hypophysectomy. Final body weights of all graft‐bearing animals were greater than those of hypophysectomized controls. The pars distalis of all grafts contained large numbers of cells immunoreactive for LH, GH, and ACTH; TSH‐immunoreactive cells were sparse. Prolactin‐positive cells were extensive in grafts of animals in which the tests were maintained, and virtually absent in grafts of animals with atrophic tests. The fiber systems of three central neuropeptides, LRF, SRIF, and ACTH, were stained and found not to enter the graft. The results suggest that pituitary grafts in the third ventricle may receive their hypophysiotropic neuropeptides from the CSF.
Surface interaction in vitro between sertoli cells and germ cells at different stages of spermatogenesis
Authors: Ziparo Elio , Geremia Raffaele , Russo Mario A. , Stefanini Mario
Published: February 2005

The presence of surface‐recognition mechanisms between somatic and germ cells of the seminiferous epithelium has been studied in the rat by an assay in vitro based on the ability of homogeneous populations of spermatogenic cells, at specific differentiative stages, to adhere to monolayers of cultured Sertoli cells. The results show that germ cells adhere specifically to Sertoli cells and that the adhesion is dependent on the differentiative stage of the germ cells. Pachytene spermatocytes show the highest ability to adhere and form typical junctional specializations with the underlying Sertoli cells, while round spermatids adhere much less to the substrate. The possible regulative role of a somatic cell‐germ cell interaction is discussed.
Morphometric study of endomyocardium and epimyocardium of the left ventricle in adult dogs
Authors: Gerdes A. Martin , Kasten Frederick H.
Published: February 2005

Quantitative light‐ and electron‐ microscopic data are reported for the endomyocardium and epimyocardium of the left ventricle in adult dogs. The endomyocardium has a markedly lower capillary density, and larger myocyte cross‐sectional area, than the epimyocardium. The sarcolemmal‐surface/cell‐volume ratio is significantly less in endocardial myocytes. No regional differences were found with regard to capillary diameter, interstitial space volume, or volume percent occupied by blood vessels and myocytes. Likewise, there are no differences in proportions of cardiac cell volume occupied by myofibrils (57%), mitochondria (25%), nuclei (1.5%), T tubes (1.2%), and sarcoplasmic reticulum (2.0%). The ratios of surface areas of T tubes and SR to their respective volumes and to cell volumes do not vary with transmural location. The regional differences and similarities are discussed in relation to general problems of blood flow in the heart and cardiac hypertrophy.
The surface morphology of embryonic and adult chick lens‐fiber cells
Authors: Kuszak J. , Alcala J. , Maisel H.
Published: February 2005

The surface morphology of lens fibers in embryonic and adult chicken lenses has been studied by scanning electron microscopy. As the elongating epithelial cells enter into a state of terminal differentiation they elaborate a number of cellular processes interconnecting neighboring fibers. The interlocking devices take the shapes of balls on a short stalk, tonguelike flaps, and fingerlike processes that fit into complementarily shaped sockets, imprints, and fingerprints, respectively, of adjoining fibers. Gap junctions comprising more than 50% of the fiber‐cell membrane may serve as ultrastructural interlocking devices. The interlocking devices and gap junctions are probably necessary to maintain fiber order—a critical requirement for lens transparency. With increased maturation, the uniform morphology of the fibers and their interlocking devices is lost. The highly repetitive ordered alignment of young uniformly shaped fiber cells acts to minimize large‐particle scatter. The results of this study show a progressive loss of uniform shape and order in chicken fibers of advanced maturity. This phenomenon of lens development may be the basis for the increase in light scattering seen in aged lenses of other species such as man.
An elementary introduction to stereology (quantitative microscopy)
Authors: Elias Hans , Hyde Dallas M.
Published: February 2005

Stereology is a branch of applied mathematics used for the three‐dimensional analysis of organs and materials from two‐dimensional measurements. Stereologic methods are versatile, easily understood, and simply applied.

This paper provides anatomists with a practical guide to stereologic techniques and concepts and to ancillary morphometric methods. These methods allow investigators to calculate volume, surface, and numerical densities; make shape determinations; and calculate size distributions for spheres and rotatory ellipsoids. Other topics covered in this article include sampling methods, correction factors for shrinkage and section thickness, index of folding, automated and semiautomated image analysis, and three‐dimensional reconstruction from serial sections.
Primary cilia of the corneal endothelium
Authors: Gallagher Betty C.
Published: February 2005

A primary cilium is a normal component of every rabbit corneal endothelial cell, rather than being a rare or sporadic organelle, as previously believed. In common with other cilia of this type it possesses an axonemal organization of 9+0 which converts distally to 8+1; it occurs only one per cell; and the basal body is accompanied by a proximal centriole. Additional structures associated with the basal body are nine transitional fibers, four striated satellite arms, and several rootlets. Ladderlike structures extend between the two centrioles to form the wall of a barrel. Reexamination of primary cilia from other tissues indicates that the ultrastructure of endothelial cilia may be characteristic of primary cilia in general.
The ability of localized implants of whole or minced dermis to disrupt pattern formation in the regenerating forelimb of the axolotl
Authors: Tank Patrick W.
Published: February 2005

The ability of localized grafts of dermis to alter pattern formation in the regenerating limb of the axolotl was studied. Longitudinal pieces of skin (1/4 of the circumference of the limb) were removed from either the anterior or the posterior surface of the upper forelimb. Epidermis was removed by immersion in versene followed by mechanical stripping. The resulting dermis was cross transplanted directly beneath the skin on the opposite side of the limb from which it originated. After 5 days of healing each limb was amputated through the graft at the midpoint of the humerus. High percentages of multiple regenerates resulted. Similar results were obtained when dermis was minced into 1 mm3 fragments prior to cross‐transplantation. Freezing or x‐raying (2000 rads) the grafts prior to cross‐transplantation abolished the effect. Dermis obtained from head skin rarely caused multiple regeneration when implanted into the upper forelimb followed by amputation 5 days later. These results demonstrate that addition of dermis to an intact limb stump profoundly alters pattern formation during regeneration. The effect is dependent upon viable cells that are capable of cell division.
Neurons of the basolateral amygdala: A Golgi study in the opossum (Didelphis virginiana)
Authors: McDonald Alexander J. , Culberson James L.
Published: February 2005

The cytoarchitecture of the opossum basolateral amygdala was studies using Golgi techniques. The neuronal morphology was similar in all nuclei of the basolateral complex, and three distinct cell classes were recognized. Class I neurons, which vary in size in different nuclei, have spiny dendrites and long, projection axons. Axon hillocks and initial axonal segments often have spinous protrusions, while more distal portions of the axon give off several beaded collaterals that arborize primarily in the vicinity of the cell. Class II neurons are smaller, spinesparse cells that are found in all nuclei of the basolateral amygdala but are greatly outnumbered by class I neurons. Axons branch and give off beaded collaterals which form a moderate to dense arborization within the dendritic field of the cell. Class II neurons exhibit considerable morphologic variability including one subtype that resembles the chandelier cell of the cerebral cortex. Varicosities (1.0‐1.5 μm swellings) found along the axonal collaterals of these amygdaloid chandelier cells do not have a uniform distribution but tend to be aggregated. Segments of the collaterals displaying such clustered varicosities sometimes form nest‐like entanglements. Clusters of varicosities have been observed forming multiple contacts with initial segments of class I axons. Class III neurons are neurogliaform cells which have many short, varicose dendritic branches that contact dendrites of class I neurons. Only the initial portions of their axons were impregnated. This study indicates that many of the cell types seen in the generalized, metatherian opossum are similar to those described in more specialized, placental mammals. This is the first description of amygdaloid chandelier cells and their contacts with the spiny initial segments of class I projection neurons.
Changes in nuclear shape and mitochondrial structure do not accompany the loss of division potential in human fibroblasts in vitro
Authors: Pool Thomas B. , Heitman Teri O. , Buck Marilyn A.
Published: February 2005

Previous studies on ultrastructural changes that occur in cultured human fibroblasts during their in vitro life‐span indicate that “senescent” cells characteristically possess structurally altered mitochondia, highly lobed nuclei, and an abundance of secondary lysosomes when compared to early passage cells. In the present study, we demonstrate that improper preparative methods can induce altered mitochondrial morphology in preparations of both IMR‐90 and HF730A fibroblasts, regardless of passage level. We also show that nuclei of both living and fixed IMR‐90 fibroblasts are ovoid in shape, not lobulate, in well‐spread cells, regardless of either the passage level or the proliferative capacity of the cell. Fibroblasts contain lobulated nuclei only when they have not spread completely on the culture substrate. Lobulations can be induced at any passage level by collagenase/trypsin or trypsin/EDTA treatment prior to fixation, but not by cytochalasin B treatment or by cold temperatures. We conclude that any treatment that affects cytoskeleton‐membrane‐culture substrate interactions will induce this aberrant nuclear morphology, but that this is not indicative of “senescence” and does not relate to proliferative decline.
Sequence of developmental alterations following acute ethanol exposure in mice: Craniofacial features of the fetal alcohol syndrome
Authors: Sulik Kathleen K. , Johnston Malcolm C.
Published: February 2005

The typical facial features of the fetal alcohol syndrome (FAS) were induced in C57B1/6J mice with acute maternal ethanol administration at gastrulation stages of embryonic development. These features include microcephaly, microphthalmia, short palpebral fissures, deficiencies of the philtral region, and a long upper lip. Scanning electron microscopic (SEM) analysis of embryos 24 hours following initial ethanol exposure at 7 days 0 hours of gestation revealed an obvious size reduction in the neural plate, which was particularly noticeable in the forebrain region. As expected, deficiencies in neural plate development at these early stages result in abnormal brain and eye formation. SEM analysis of later embryonic stages revealed the development of closely set olfactory placodes with resultant deficiencies in the medial nasal prominences (that area responsible for forming the philtral region of the upper lip, the alveolar ridge containing the upper incisors, and the anterior portion of the hard palate—the primary palate). Cleared skeletal preparations of affected newborns had marked premaxillary bone deficiencies. One of the most prevalent known human teratogens has a major malformation‐inducing effect on gastrulating embryos, a developmental stage present in human embryos prior to pregnancy recognition by most women.
Ultrastructure of the placenta and fetal membranes of the dog: II. The yolk sac
Authors: Lee Sue Y. , Anderson John W. , Scott Grayson L. , Mossman Harland W.
Published: February 2005

Yolk sacs from dogs at 40, 50, and 60 days of gestation were examined by electron microscopy. Free ribosomes, mitochondria, and rough endoplasmic reticulum (rER) are more prominent in both endoderm and mesothelium at 40 and 50 days than at 60 days, suggesting a greater synthetic capacity at the earlier stages. Smooth endoplasmic reticulum (sER) and glycogen are also present in greater amounts in the endoderm in the earlier stages. In the mesothelium, however, low amounts of sER and glycogen are consistently present. Certain possibilities relative to the nature of the synthetic activities in these two tissues are discussed. Large amounts of smooth‐surfaced vesicles were observed along the basal edges of the 60‐day mesothelium; they are indicative of transport processes occurring at this time. As gestation proceeds, in both endoderm and mesothelium, the Golgi complex remains well developed, there are more numerous lysosomelike bodies, and bundles of intermediate filaments either increase or become more diffused. In some endoderm cells at 60 days, large vacuoles and dense glycogen deposits were noted. These observations indicate that degenerative processes are gradually occurring in the endoderm and mesothelium as parturition draws near. Erythropoiesis occurs in the mesenchyme at 40 and 50 days. At 40 days also, segments of endothelium were seen within blood islands, indicating that the endothelial lining of some yolk sac vessels differentiates from cells located in the interior of such islands.
Comparative ultrastructure of the inner capsule of the muscle spindle and the tendon organ
Authors: Ovalle William K. , Dow Pierre R.
Published: February 2005

The ultrastructure of inner capsule cells of the vertebrate muscle spindle was studied by transmission electron microscopy and compared with that of homologous cells in the tendon organ. Aside from variations in their complexity and pattern of organization, cells of the inner capsule in these two sensory receptors exhibited marked similarities in fine structure. The virtual absence of basal lamina in the region of the nucleated soma as well as on the branching cytoplasmic extensions of these cells was noted. In the inner capsule of both end organs, three kinds of intercellular specialization were encountered. Cell processes were typically linked together at multiple sites by intermediate junctions. In addition, focal points of membrane fusion between two or more cellular profiles were identified as tight junctions. In more extensive regions of plasma membrane overlap, gap junctions were also discerned. It seems probable that these sites along the inner capsule represent areas of mechanical and electrical linkage, enabling contiguous cells to function as a synchronous unit. Tight junctions may also provide the inner capsular sheath with specific permeability‐barrier characteristics. Elements of the Golgi complex and associated presecretory vesicles and cytoplasmic granules were prominent. Their presence implicates these cells in the elaboration of the paracellular connective‐tissue matrix occupying the intracapsular spaces of both receptors. The close resemblance of these cells to endoneurial fibroblasts of peripheral nerve and to hyalocytes of the vitreous body is emphasized. It is likely that, regardless of species examined, cells of the inner capsule in both receptors play an overall protective role in the formation, maintenance and regulation of their luminal paracellular contents.
Morphometric analyses on the muscles of exercise trained and untrained dogs
Authors: Čabrić M. , James N. T.
Published: February 2005

Nine adult dogs were subjected to an endurance training program consisting of gradually increasing periods of treadmill exercise. Biopsies of vastus lateralis muscles taken prior to and on completion of the training program were used to study the alterations in the capillary network and muscle‐fiber nuclei.

Combined morphometric and stereological analyses showed that the total length of capillaries (LV) and their total surface area (SV) per unit volume of muscle was significantly increased during training.

Changes in the properties of myonuclei following training were also studied. Highly significant increases in the number of nuclei per unit volume of muscle (NV) were found. The increase in the numerical density of muscle‐fiber nuclei would seem to indicate that the new nuclei were formed in the muscle during prolonged training. The relative amounts and distribution of heterochromatin and euchromatin were measured in trained and untrained dogs using a simple point‐counting and random‐transect technique. Their content of the different types of chromatin (volume functions and chromatin patch sizes in micrographs) were found to be altered significantly as a result of the training. The findings were consistent with the view that the amount of euchromatin within nuclei varies according to the degree of cellular activity.
The aging male rat: Structure and function of the kidney
Authors: Haley Diane P. , Bulger Ruth Ellen
Published: February 2005

The progression of anatomic and functional changes that occur with aging in normal male Sprague‐Dawley rats was investigated. Renal function studies were followed by vascular perfusion fixation of the kidneys. The kidneys were examined with light microscopy and scanning and transmission electron microscopy.

The glomerular filtration rate of 12‐month‐old rats (0.30 ± 0.06 ml/min/100 gm body weight) was significantly lower (P < .05) than the rates of the 3‐month‐old (0.91 ± 0.08 ml/min/100 gm body weight) and 5‐month‐old (0.99 ± 0.16 ml/min/100 gm body weight) rats. Urine protein levels were moderately elevated in 12‐month‐old rats. Structural changes mainly involved the renal corpuscle and proximal tubule. The parietal layer of Bowman's capsule wa transformed from a squamous to a columnar epithelium resembling that of the proximal tubule in 48% of the capsules surveyed in 12‐month‐old rats. This value was significantly higher (P < .05) than that of the 5‐ (14%) or 3‐ (6%) month‐old rats. Thin sheets of cytoplasm extended from podocytic cell bodies over the layer of pedicels. The proximal tubule displayed focal areas of cell injury and necrosis. Basement membranes associated with the renal corpuscle, glomerulus, and proximal tubule were considerably thickened in the oldest group of rats. Some cellular infiltration occurred in the interstitium. Therefore, kidneys of aging Sprague‐Dawley rats exhibited capsular metaplasia, death, and injury of proximal tubular epithelial cells, and other structural changes not seen in younger animals. Some of these changes may underlie the functional deterioration of their kidneys.
Postnatal development of spiral ganglion cells in the rat
Authors: Schwartz Ann Marie , Parakkal Marianne , Gulley Robert L.
Published: February 2005

The postnatal development of the spiral ganglion in the albino rat was studied using light and electron microscopy. The morphological characteristics distinguishing type 1 from type 2 spiral ganglion cells were defined, and the critical period for distinguishing the two types of neurons was identified. At birth, the spiral ganglion consists of a homogeneous population of small, densely packed, spherical cells that have large cytoplasmic‐to‐nuclear ratios. During the first postnatal week, the cells mature slowly. At this period the myelin sheath around the cell bodies generally consists of only a few layers of loose myelin. Long glial fingers extend around the cell processes and soma, particularly the filopodial extensions of the somatic membrane. Type 2 spiral ganglion cells can be distinguished at postnatal day 8. Viewed with the phase‐contrast microscope these cells are smaller and have more darkly staining nuclei and more lightly staining cytoplasm than the type 1 cells. The most characteristic ultrastructural features of the type 2 neurons are the densely packed neurofilaments in the cytoplasm and lack of compact myelin around the cell soma. By day 14, spiral ganglion cells are morphologically mature, although the myelin sheath continues to thicken. The results are discussed in relation to the electrophysiological development of the auditory system and the morphological maturation of the organ of Corti.
Cell density and cell generation in the periodontal ligament of mice
Authors: McCulloch C. A. G. , Melcher A. H.
Published: February 2005

The number of cell nuclei per mm2 and the volume density of cell nuclei and blood vessels in the periodontal ligament at different levels of the mesial root of the first mandibular molar of the adult mouse and in different areas of the ligament at each level have been examined in the light microscope. Significantly higher numbers of cell nuclei per mm2 were observed adjacent to bone, cementum, and blood vessels than in the avascular body of the ligament at all levels and on all aspects of the root. This distribution of number of cell nuclei per mm2 was constant over 41/2 months of aging and a doubling of body weight. The volume density of cell nuclei was significantly higher in cells adjacent to bone and cementum and in gingival connective tissue than in both the vicinity of blood vessels and the body of the ligament. The blood vessels, which were present predominantly in the bone‐related half of the ligament, were absent from the zone immediately adjacent to cementum.

The labeling indexes of periodontal ligament cells were determined from autoradiographs of the mesial root of the first mandibular molar of the mouse after pulse‐labeling with 3H‐Tdr. Labeling indexes were highest in zones adjacent to blood vessels, and the labeling index was significantly higher in the middle of the ligament than in zones adjacent to bone and cementum, and consequently was inversely related to cell density.
Ultrastructure of cartilage from young adult sea lamprey, Petromyzon marinus L: A new type of vertebrate cartilage
Authors: Wright Glenda M. , Youson John H.
Published: February 2005

Ultrastructural observations of cartilage from adult sea lamprey, Petromyzon marinus, reveal a highly cellular cartilage with an unusual extracellular matrix. The avascular cartilage is surrounded by a vascular perichondrium, which consists of dense connective tissue containing fibroblasts, collagen fibrils, and microfibrils. The cells (chondrocytes) vary in morphology in different parts of the cartilage in a way that may reflect their state of activity. Chondrocytes within the peripheral cartilage contain tubulo‐vesicular structures along the cell surface, an extensive lamellar rough endoplasmic reticulum, and a well‐developed Golgi complex with associated vesicles and vacuoles. The presence of material within the Golgi elements that resembles components of the extracellular matrix suggests the involvement of the peripheral chondrocytes in the synthesis and secretion of the matrix components. Chondrocytes within the central cartilage are hypertrophied and contain a pale cytoplasm with a reduced number of organells that are widely spaced throughout the cell. The appearance of the organelles within these cells suggests that they are not as actively involved in the production of the matrix as those of the peripheral cartilage. The extracellular matrix consists of a dense network of randomly arranged, branched, noncollagenous matrix fibrils 15–40 nm in diameter and varying amounts of electron‐dense matrix granules. Due to the unique nature of its extracellular matrix, the cartilage of the lamprey cannot be likened to any of the known vertebrate cartilages and, therefore, must be considered a new type of vertebrate cartilage.
Light microscopic immunolocalization of type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin in the basement membranes of a variety of rat organs
Authors: Laurie G. W. , Leblond C. P. , Martin G. R.
Published: February 2005

Immunohistochemical methods were used to determine whether type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan were present in diverse basement membranes. Antisera or antibodies against each substance were prepared, tested by enzyme‐linked immunosorbent assay, and exposed to frozen sections of duodenum, trachea, kidney, spinal cord, cerebrum, and incisor tooth from rats aged 20 days to 34 months. Bound antibodies were then localized by indirect or direct peroxidase methods for examination in the light microscope.

Immunostaiing for type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan was observed in all of the basement membranes encountered. Fibronectin was also found in connective tissue. In general, the intensity of immunostaining was strong for type IV collagen and laminin, moderate for heparan sulfate proteoglycan, and weak for fibronectin. The pattern was similar in the age groups under study. Very recently the sulfated glycoprotein, entactin, was also detected in the basement membranes of the listed tissues in 20‐day‐old rats.

It is accordingly proposed that, at least in the organs examined, type IV collagen, laminin, fibronectin, heparan sulfate proteoglycan, and entactin are present together in basement membranes.
Non‐lymphoid cells of the anuran spleen: An ultrastructural study in the natterjack, Bufo calamita
Authors: Barrutia M. S. García , Leceta J. , Fonfría J. , Garrido E. , Zapata A.
Published: February 2005

The present study is concerned with the ultrastructure of the spleen in the natterjack, Bufo calamita (Anura, Bufonidae), with special emphasis on the structure and function of the non‐lymphoid elements occurring in the red and white pulp. The organ consists of two clearly distinguishable areas, the white and the red pulp, separated by a prominent marginal zone. Thus, the pattern of lymphocytic arrangement in the spleen of Bufo calamita corresponds to a follicular model and is similar to that reported in the primitive anurans of the Pipidae family, such as Xenopus laevis. The white pulp presents a reticular network consisting of two different cell types and free cells, such as lymphocytes, plasma cells, and macrophages. The red pulp is formed by cell cords, where reticular cells and fibers, macrophages and lymphocytes occur, and blood sinuses which some times contain developing erythroid elements. Colloidal carbon particles injeced via the lymph sac are trapped exclusively by free macrophages in the red pulp which then move through the marginal zone to the white pulp. Giant, ramified, non‐phagocytic cells appear in both white and red pulp. They have been functionally related with the trapping of antigen‐antibody complexes on their surface, and a possible dendritic significance is discussed on the basis of their morphologic characteristics.
Three‐dimensional reconstruction of a rat stage V Sertoli cell: III. A study of specific cellular relationships
Authors: Russell Lonnie D. , Tallon‐Doran Maureen , Weber James E. , Wong Vivien , Peterson R. N.
Published: February 2005

Specific Sertoli–Sertoli and Sertoli–germ‐cell contacts and/or junctions were investigated employing micrographs used to reconstruct serially a model of a rat stage V Sertoli cell. The Sertoli–Sertoli junctional contact areas occurred in a belt‐like arrangement near the base of the Sertoli cell. This configuration is consistent with their proposed function as a sealing element limiting the passage of materials toward the tubular lumen. Sertoli ectoplasmic specializations also formed a continuous belt, or band, around the reconstructed cell at the junctional contact area. Eighteen Sertoli–Sertoli tubulobulbar complexes were found; some (12 in number) invaginated the reconstructed cell, while others (6) emanated from it. Of 37 round germ cells that were sectioned in their entirety and adjoined the reconstructed cell, 23 displayed desmosome–gap junctions with either the reconstructed cell or an adjoining cell. Since there were multiple junctions connecting some germ cells to Sertoli cells, the total number of junctions was much greater (35). Desmosome–gap junctions of the Sertoli cell were numerous connecting pachytene spermatocytes, less numerous connecting type B spermatogonia, and even less numerous connecting step 5 spermatids; and none was seen joining Sertoli cells with elongate spermatids. Most desmosome‐gap junctions join germ cells to the body of the Sertoli cell at its basal aspect. Their numbers and position indicate that they play a role in the maintenance of the integrity of the seminiferous epithelium and may provide a route for cell‐to‐cell communication. Ectoplasmic specializations of the reconstructed cell were seen facing only 3 of 37 round germ cells, and 7 ectoplasmic specializations from adjoining Sertoli cells faced these germ cells, all of which were step 5 spermatids. That there were no ectoplasmic specializations facing pachytene cells indicates that ectoplasmic specializations are not acquired as these cells pass through Sertoli–Sertoli junctions, but are acquired later in spermatogenesis.
Histochemical studies on the distribution of thiamine pyrophosphatase and enzymes related to carbohydrate metabolism in the intercalated neurons of the rat supraoptic nucleus
Authors: Iijima Koichi , Saito Hitoshi
Published: February 2005

Histochemical studies have been conducted by applying hexokinase (HK), aldolase (AD), glyceraldehyde‐3‐phosphate dehydrogenase (G3), succinate dehydrogenase (SDH), glucose‐6‐phosphate dehydrogenase (G6PD), and thiamine pyrophosphatase (TPPase) methods, as well as Nissl staining and Gomori's chrome‐alum‐hematoxylin‐phloxine (CHP) methods to intercalated neurons of the supraoptic nucleus (SO) on Wistar strain rats. Intercalated neurons reacted weakly to the AD, G3, G6PD, and SDH tests, indicating that they belong to the category of ordinary neurons with low carbohydrate metabolism. Many fibrous astrocytes showing strong HK reactions surround neurosecretory neurons. However, they do not surround intercalated neurons with mild HK activity. These results indicate that the latter receive a poor supply of energy from glucose in the circulating blood in contrast to the former. Intercalated neurons are very rich in Nissl substance but lack CHP‐positive material. They may have a high potential for synthesizing protein. The principal morphological features of the TPPase‐positive Golgi material are peculiar and heterogeneous shape and poor development. These findings together with mild G6PD activity suggest that intercalated neurons are very likely to have poor synthesizing activity.
Several cytokinetic methods for showing circadian variation in normal murine tissue and in a tumor
Authors: Rubin N. H. , Hokanson J. A. , Mayschak J. W. , Tsai T. H. , Barranco S. C. , Scheving L. E.
Published: February 2005

Circadian rhythmicity in cell proliferation was studied by several cytokinetic techniques in 8‐week‐old CD2F1 and Swiss male mice. In separate experiments on four different dates, subgroups of six or seven mice (fed ad libitum and standardized to 8 hours light alternating with 16 hours of darkness) were killed at 3‐hour intervals over a period of 24–48 hours. Cosinor analyses were used to determine the parameters of circadian periodicity in the data. Flow cytometric (FCM) analyses of DNA synthesis in tongue and stomach were compared with estimates of tritiated thymidine (3HTdR) incorporation into the DNA in these tissues. Circadian variation in tongue epithelium was reproducible in phasing and in range‐of‐change (100–140%) in seven 24‐hour studies. The proportion of cells in G1 and G2 in tongue epithelium also demonstrated a circadian periodicity. When DNA synthesis in stomach was analyzed by the two methods, the results were entirely different and thus not comparable. The circadian rhythms in 3HTdR uptake agreed with those reported previously, but results of analyses by FCM were less certain, since epithelium of this organ could not be analyzed separately. Circadian rhythms were detected by FCM in G1, S, and G2M in Ehrlich ascites carcinoma (EAC). The mitotic index of this tumor varied with a circadian periodicity similar to that of the FCM‐derived rhythm in G2M. This study validates the reliability of older techniques, such as 3HTdR uptake and mitotic indices, and suggests that circadian rhythms can be important in studies of cellular properties using FCM.
Abnormal hepatic lipid accumulation following treatment of diabetic rats with insulin and a high‐carbohydrate, fat‐free diet
Authors: Drake Richard L. , Thompson Ed W. , Parks William C.
Published: February 2005

This study correlates the morphological and biochemical events during the accumulation of hepatic lipids in diabetic rats in response to insulin treatment and a high‐carbohydrate, fat‐free diet. Alloxan‐diabetic rats were fed a high‐carbohydrate, fat‐free diet and treated with insulin for 12, 36, or 60 hr or 4.5 or 6.5 days. Samples of livers were obtained for determination of malic enzyme activity and the histochemical demonstration of lipids. An increased accumulation of hepatic lipids, although delayed, was observed following insulin treatment of diabetic rats fed the special diet. Small lipid droplets were visible after 36 hr of treatment, which later increased and coalesced into larger droplets present in all hepatocytes. Maximal accumulation was observed at 4.5 days of treatment. These changes were paralleled by an increase in the activity of hepatic malic enzyme. By 6.5 days of treatment, the lipid content of the hepatocytes had decreased and a periportal pattern was discernible. In contrast, malic enzyme activity continued to increase through 6.5 days of treatment. By comparison, no hepatic lipid accumulation occurred in regular chow‐fed diabetic rats receiving insulin treatment or in diabetic rats placed on the special diet alone. These results suggest that the combination of insulin treatment and a high‐carbohydrate, fat‐free diet caused an imbalance in the production and mobilization of hepatic lipids.
Surface architecture of the mucosal epithelium of the cat trachea: I. Cartilaginous portion
Authors: Tandler Bernard , Sherman James M. , Boat Thomas F.
Published: February 2005

The mucosal covering of the cartilaginous portion of the cat trachea was studied by correlated light, transmission‐electron, and scanning‐electron microscopy. While in some areas the ciliated pseudostratified epithelial lining is fairly smooth in contour, in other areas it contains longitudinally oriented, cilia‐lined clefts. Ducts from submucosal glands sometimes open into the base of these clefts, or into funnel‐shaped stomata that are lined by either ciliated or microvillus‐rich cells. Specialized epithelial cells are occasionally associated with the clefts or with other regions of surface epithelium. In single sections, these cells appear to contain a cilium‐lined vacuole, but serial sectioning has demonstrated that these apparent vacuoles actually are long intracellular inaginations in enormously elongated cells that extend longitudinally in the plane of the epithelium. The function of these cells is undetermined. Basal cells are attached to the lamina densa by means of hemidesmosomes that consistently lack peripheral densities; in contrast, the tall columnar cells have no hemidesmosomes.
Development and melatonin content of the deep pineal gland in the syrian hamster
Authors: Sheridan Michael N. , Rollag Mark D.
Published: February 2005

The morphological relationships between the superficial and deep pineal glands of neonatal Syrian hamsters are described at both light and electron microscopic levels. In addition, melatonin contents in the two glandular masses are compared throughout a 14 hr light:10 hr dark photoperiod in 20‐day‐old hamsters. It has been found that the pineal anlage begins to separate into deep and superficial components between the first and third postnatal days of life. Separation is usually complete by day 12. The fine structure of the deep gland is similar to that of the superficial gland throughout development. By the time of weaning (20 days of age), the young hamsters exhibit distinct nighttime elevations of melatonin in both the superificial and deep glands, the quantities in the deep gland being approximately 5% those of the superficial pineal. Like that of the superficial pineal, the rise in deep pineal melatonin content can be abolished by exposure of hamsters to light.
Light and electron microscopic cytochemistry of glycoconjugates in the rectosigmoid colonic epithelium of the mouse and rat
Authors: Thomopoulos G. N. , Schulte B. A. , Spicer S. S.
Published: February 2005

The several cell types in mouse and rat rectosigmoid colon have been examined with light and electron microscopic methods for localizing and characterizing complex carbohydrates. Mucous cells, also termed vacuolated cells, and goblet cells comprised most of the deep crypt epithelium in both species, and absorptive columnar cells and goblet cells mainly populated the more superficial epithelium of the upper crypts and main lumen. Occasional tuft cells and enteroendocrine cells were also encountered.

Transitional cells structurally intermediate between mucous cells and absorptive cells contained granules characteristic of mucous cells and vesicles like those of columnar absorptive cells. These intermediate cells supported the concept of replacement of mucous by absorptive cells through transformation of mucous into absorptive cells. The intermediate cells also contained numerous lysosomes often in apparent fusion with mucous granules, indicating crinophagic disposal of mucous granules as a mechanism in the cell transformation. Glycoconjugate in absorptive cell vesicles resembled that coating the apical plasmalemma and appeared to represent the source of the glycocalyx of the brush border. Complex carbohydrate in these vesicles differed cytochemically from that of the mucous cell granules, which release their content into the crypt lumen. The absorptive cell vesicles, therefore, constitute an organelle distinct from the mucous cell granules rather than an atrophic form of the latter in a more mature cell.

Goblet cells differed in failing to transform morphologically with age but changed in the cytochemical characteristic of their secretion during migration up the crypts. Terminal N‐acetylglucosamine residues diminished, while terminal sialic acid‐galactose dimers increased during the upward migration, indicating activation of glycosyl transferase synthesis in relation to goblet cell maturation.

Glycoconjugate in secretion of mucous cell granules differed markedly from that in goblet cell granules, and content of both organelles differed from that of absorptive cell vesicles. However, secretion in mucous cell granules appeared generally similar for mice and rats with minor exceptions, and secretion in goblets of mice generally resembled that in goblets of rats. Cells interpreted tentatively as Kulchitsky cells stained for high content of fucose with the Ulex europeus I lectin. Globoid leukocytes infiltrating the epithelium of the rat but not the mouse rectosigmoid colon resembled globoid leukocytes in rat tracheal epithelium and, like the latter, appeared to derive from mast cells.
Chronobiology of the intestinal tract of the mouse
Authors: Scheving L. E. , Tsai T. H. , Scheving L. A.
Published: February 2005

This paper summarizes recent and continuing work on circadian rhythms in the alimentary tract of rodents; these include: (1) cell proliferation, (2) activities of intestinal enzymes, and (3) behavioral aspects of spontaneous feeding and drinking. All regions of the intestinal tract show marked circadian behavior in cell proliferation. The roles of the light‐dark cycle and meal timing in synchronizing such rhythms are discussed as well as the influence of epidermal growth factor, insulin, glucagon., and ACTH 1‐17. Attention is called to the potential importance of these rhythms to basic research and medicine. Other circadian rhythms in the alimentary tract are reviewed briefly, such as those characterizing a host of intestinal enzymes, monosaccharide transport, and the height and width of the villi. Many of these have been shown to be cued to a feeding schedule; however, a number of the enzyme rhythms persist for one or two cycles in fasting animals, and this also is the case for the cell‐proliferation rhythms.

After having been acclimated to a circadian feeding schedule (within a range of 23–30 hr), rodents can on subsequent days anticipate the food an hour or more prior to its arrival. Some enzymes behave in a similar manner in that their activities increase prior to the expected intake of the daily food. These anticipatory response rhythms are under endogenous control, since both will persist in the fasted animal and both will free run when a mouse is placed under constant conditions. Somehow these animals are able to measure circadian intervals of time. This challenges the concept that the oscillations seen in enzyme activities are simply a passive consequence of feeding and fasting, respectively.
The clinical application of chronobiology to oncology
Authors: Hrushesky William J. M.
Published: February 2005

The introduction to medical practice of chemical agents for fighting human cancer some 30 years ago brought hope to a field of medicine previously shrouded in despair and impeded by superstition. Gradually more and better agents have become available to the physician and to the patient suffering from cancer. The physician‐scientist has, in turn, learned a great deal about normal and abnormal cellular biology by using these drugs as probes. The observations that certain tissues and certain tumors share patterns of drug toxicity have led to a broadening of biologic understanding and to the use of combinations of drugs with shared antitumor activity and unshared toxicities. This empiric art of cancer chemotherapy has resulted in great progress in the treatment of a large number of advanced cancers. As important, however, is that this experience has resulted in knowledge which is leading to the development of rationally designed therapeutic regimens; to drug analogues seeking greater therapeutic‐toxic ratios; to the development of methods for chemically interfering with toxic drug effects while allowing or enhancing antitumor effect; and to work defining effects of drug timing. Drug timing research considers drug dosage in respect to the timing of a drug relative to the timing of other drugs (drug‐time‐drug interactions) or to other doses of that same drug (drug‐drug interval); the order of drugs (drug‐drug sequence); and the timing of drugs relative to an internal organismic time structure (time‐drug interactions). Data in this brief review clearly show that drug timing needs to be considered when designing rational chemotherapy for a living organism suffering from a cancer. The beautiful spatiotemporal complexity of life is not to be ignored or avoided, but should be considered as a golden opportunity to use what few imprecise chemical weapons we have a little more effectively.
Leydig cell development in the pig testis during the late fetal and early postnatal period: An electron microscopic study with attention to the influence of fetal decapitation
Authors: Van Vorstenbosch C. J. A. H. V. , Colenbrander B. , Wensing C. J. G.
Published: February 2005

The ultrastructure of fetal and postnatal pig Leydig cells was studied from 75 days postcoitum (p.c.) to 1 month after birth. Additionally, decapitated fetuses from 75 days p.c. until birth were used to study the effect of deprivation of gonadotrophins on the ultrastructure of Leydig cells.

Normal Leydig cell development was characterized by a change in smooth endoplasmic reticulum (SER). Next to branched tubular SER, whirls of elaborate and tightly packed SER membranes appeared. The amount of SER increased with age but decreased slightly before the end of the observation period. Rough endoplasmic reticulum (RER) was a minor component. Large bundles or whirls of intermediate filaments were abundant until just before birth; thereafter, they decreased drastically. Peroxisome‐like structures and crystalloid bodies were observed with increasing frequency from 75 days p.c. and 20 days postpartum onward. Polygonal lysosome‐like dense bodies transformed into complex membranous structures especially after birth. Giant mitochondria occurred in the late fetal and postnatal period.

From 75 days p.c. onward fully developed Leydig cells were scarce in testes of decapitated fetuses. Leydig cell characteristics disappeared toward the end of the fetal period; only the cell shape, the large bundles or whirls of intermediate filaments, some scarce polygonal lysosome‐like dense bodies, and RER remained, but SER was negligible. Progressive hemorrhages apparent in situ were correlated positively with fetal age. The dependency of Leydig cells upon LH began between 60 and 75 days postcoitum.