bluuebunny/crossref_metadata_2025 huggingface dataset:
Membrane differentiation in the golgi apparatus of mammalian urinary bladder epithelium
Authors: Alroy Joseph , Merk Frederick B. , James Morré D. , Weinstein Ronald S.
Published: February 2005

The endomembrane system in superficial and intermediate epithelial cells of mammalian urinary bladder was studied by cytochemistry, thin‐section and freeze‐fracture electron microscopy to determine the sites where special forms of membrane differentiation first appear. Glutaraldehyde‐resistant NADH‐ferricyanide reductase, distinctive 11–12 nm intramembrane particles (IMP), and asymmetry of membrane leaflets served as markers of membrane maturation. The three markers were specifically associated with the maturing face of Golgi apparatus and were absent from the remainder of the endomembrane system. Activity of this enzyme was associated with the lateral regions of the maturing face, fusiform vesicles, and the plasmalemma. Asymmetric unit membrane (AUM) plaques were not observed in the Golgi apparatus per se but were present in immature fusiform vesicles that had not detached from the maturing face. When freeze‐fracture replicas and thin sections were compared, randomly arranged 11–12 nm IMP first appeared in maturing face membranes that were adjacent to clusters of “free” polyribosomes in the Golgi apparatus region. The proximity of these polyribosomes suggests that they may be related to the coincident appearance of the 11–12 nm IMP in the maturing face membrane. Our observations support the hypothesis that membranes undergo differentiation during “flow” through compartments of the endomembrane system. The lateral regions of the maturing face of the Golgi apparatus appear to be a critical location for the morphogenesis of plasma membranes in urinary bladder.
Scanning electron microscopy studies of the vascular pole of the rat glomerulus
Authors: Frank Martina , Kriz Wilhelm
Published: February 2005

The vascular poles of 30 renal corpuscles were studied in critical‐point dried renal cortex of the Munich‐Wistar rat by scanning electron microscope (SEM). In 28 cases one afferent and one efferent arteriole were observed; one afferent and two efferent arterioles were found in two cases only. The same study was done in the Sprague‐Dawley rat, where 34 renal corpuscles were examined. One afferent and a single efferent arteriole were found in 32 cases; in one case only one afferent and two efferent arterioles were observed. In another case it was questioned whether a single or a double efferent arteriole arteriole is present. In addition, the specimens allowed an evaluation of the area where the extraglomerular mesangium passes into the mesangial cells of the glomerular tuft. This area was found to be rather small to represent a “punctum fixum” for a contraction of the entire mesangium.
Freeze‐fracture studies of neonatal mouse incisors
Authors: Hasty David L.
Published: February 2005

Differentiation of preodontoblasts to odontoblasts and preameloblasts to ameloblasts during development of the mouse mandibular incisor proceeds in a gradient from the area of the odontogenic organ, where undifferentiated ectomesenchymal and epithelial cells proliferate, toward the incisal tip where mature tooth tissues, dentin and enamel, are present. The freeze‐fracture technique has been used in the work presented here to study cell membrane ultrastructure of preodontoblasts and preameloblasts at several stages of differentiation. At early stages of differentiation, cuboidal preameloblasts are joined together distally by numerous gap junctions. Relatively fewer junctions occur elsewhere on the lateral plasma membranes, but gap junctions frequently occur proximally between preameloblasts and stratum intermedium cells. As differentiation proceeds and the cells become columnar, distal and proximal junctions persist. Tight junctions, however, were not observed at any of the stages studied. Intramembrane particle concentration of the lateral preameloblast plasmalemma appears to increase as differentiation proceeds. Odontoblasts are also joined distally by numerous gap junctions which persist through later stages of differentiation. Although odontoblast cell processes were observed to project toward the preameloblast layer, no clear points of cell to cell contact or defined intercellular junctions between the two cell types were observed.
Dynamics of lysosomal elements in pulmonary alveolar macrophages: II. Transitory intracytoplasmic events in activated cells
Authors: Sorokin Sergei P.
Published: February 2005

Intracytoplasmic interactions were examined in iron oxideexposed and ‐unexposed alveolar macrophages of mice by electron microscopy and ultrastructural cytochemistry. Submicronic‐sized particles are taken up by microendocytosis into 800‐Å tubules that sometimes open up into a large vacuole located midway between the plasmalemma and the Golgi complex and sometimes lead directly to that organelle, which is reactive for acid phosphatase while cells are only modestly engaged in lysosomal synthesis and then serves as the main locus for formation of heterolysosomes. In more activated cells, nascent lumbricoid lysosomes are budded directly off branches of the granular reticulum; in consequence, much of the newly synthesized acid phosphatase bypasses the Golgi apparatus, and heterolysosomes are formed throughout a widened expanse of cytoplasm. The lumbricoids exist either as free elements or as a labyrinthian network of lumbricoid units, and the two forms appear interconvertible. They are short lived in contrast to larger rounded lysosomes more commonly present, many of which are heterolysosomes as judged by their content of ingested particles. Lumbricoids readily fuse with exoplasmic structures; indeed, in some lumbricoid‐producing cells terminal segments of the reticulum may share this propetry to a degree, since they resemble transitional elements when extended along large phagosomes. Microendosomes can be taken up into lumbriciods, but if the endosome is larger, lumbricoids will adhere to its surface and become part of the digestive vacuole. A labyrinth is formed to envelop large phagosomes or regions of cytoplasm marked for autophagy. The interior is invaded by branches and digestion ensues. In active macrophages the Golgi apparatus is enlarged. The centrioles organize an array of microtubules about themselves, and individual Golgi stacks are turned outward to give the organelle better access to phagosomes and lysosomes. In less active cells the microtubules disappear, and the stacks reform in a circle about the diplosome. Alveolar macrophages therefore make a variety of lysosomes. Depending on cellular activity, one kind or another predominates. Few of them fall cleanly into “primary” and “secondary” classes, and in their interactions with other cellular structures they are influenced by mechanisms operating on microscopic as well as molecular scales.
Gross morphological analysis of limb regeneration in postmetamorphic adult Ambystoma
Authors: Young Henry E. , Bailey Claudia F. , Dalley Bernell K.
Published: February 2005

Due to the great disparity between regeneration times for the larval salamander (40 days), axolotl (30+ days), newt (44 days), and adult salamander (155 to 370 days), a staging system was devised so correlative comparisons could be made between regenerative model systems. The sequence was based on two criteria: (1) the stages should be similar to previously reported sequences for the newt, axolotl, and larval salamander, and (2) the stages must be readily recognizable by examination of the external morphology in the living state. Postmetamorphic adult land‐phase Ambystoma were amputated through the forearm, placed within survival conditions, and observed until regeneration was completed. Of the initial 160 salamanders, 157 (98%) progressed through 11 clearly defined stages of regeneration. A side‐by‐side comparison of the staging sequence for land and aquatic phase urodeles is given along with a summary of key external morphological characteristics for the adult salamander. It was noted that as the length of time for regeneration decreased, the relative ratio of the nerves innervating the limb (spinal nerves 4, 5, and 6) increased for the four species of Ambystoma examined: A. annulatum, 324 to 370 days postamputation (dpa) with a 1:1:1 neural tissue ratio; A. maculatum, 255 to 300 dpa with a 2:2:1 ratio; A. texanum, 215 to 250 dpa with a 2:2:2 ratio; and A. tigranum, 155 to 180 dpa with a 2:3:3 ratio.
Morphological evidence of the shedding of chondrocytes from the articular surface in neonatal rats: Relationship to the interlacunar network
Authors: Cole Madison B. , Narine Kamal R. , Ellinger Joan
Published: February 2005

The superficial zone of the femoral head articular cartilage of 5‐ to 15‐day old rats was examined by light and electron microscopy for evidence of shedding into the joint space. Chondrocytes deepest in the superficial zone were round, surrounded by a capsule, and connected to adjacent chondrocytes by the interlacunar network, whereas cells in the middle ofthe zone appeared similar but with less cytoplasm. At the articular surface, chondrocytes were small, with pyknotic nuclei and poorly defined organelles. These cells occasionally protruded from the articular surface but maintained at least partial connection with the network and their capsule. Depressions in the articular surface were lined with material similar to that of the network and were the only locations found where the network did not terminate at a cell surface. This static evidence suggested at least two hypotheses: (1) Degenerating chondrocytes moved up through the superficial zone tothe articular surface and were shed into the joint space. This movement maybe facilitated by the network as part of neonatal cartilage development. (2) During joint formation, the surface of the articular cartilage was eroded down tothe chondrocytes, which were exposed to the joint fluid, causing cell degeneration, death, and shedding. Evidence of cell shedding was rarely seen after 2 weeks of age. Likewise, the interlacunar network disappeared from the superficial zone during this period. A physiological as well as structural relationship may exist between the chondrocytes and interlacunar network.
The effect of osmium postfixation and uranyl and lead staining on the ultrastrucure of young enamel in the rat incisor
Authors: Nanci A. , Bai P. , Warshawsky H.
Published: February 2005

Enamel crystallites are electron opaque without osmium or heavy metal staining and give a crystalline electron diffraction pattern. Since the opacity and diffraction pattern are abolished from ultrathin sections of young enamel by floating on distilled water (Bishop and Warshawsky, 1982), the possibility that aqueous staining may also remove crystallites was tested. In addition, the effect of osmium postifixation on crystallite structure was examined.

Rat incisors fixed by perfusion with a mixture of aldehydes were either nonosmicated or osmicated prior to dehydration. Incisor segments in the region of inner enamel secretion were embedded in the same Epon block to ensure reliable comparison. Osmicated enamel was more intensely stained with toluidine blue and more electron opaque than nonosmicated enamel. No other structural differences were seen. However, crystallites in osmicated enamel were more resistant to grid demineralization and electron beam damage. Routine staining was done by floating sections on solutions of uranyl acetate and lead citrate; sections were also floated on similar solutions from which the heavy metals were omitted. These solutions removed the electron opaque crystallites from the youngest enamel. Stained sections showed electron opaque crystallite‐like structure similar to unstained enamel. When sections that were extracted by the solutions from which the metals were omitted were restained, they appeared identical to routinely stained enamel. It was conclud that staining of young enamel removes the crystallites and reveals only the organic matrix.
The liver hemopoietic environment: II. Peroxidase reactive mouse fetal liver hemopoietic cells
Authors: Medlock Eugene S. , Haar Jack L.
Published: February 2005

Through the combined use of peroxidase cytochemistry and examination at the ultrastructural level, the present study has identified liver hemopoietic foci containing three forms of erythropoietic cells, two forms of myelopoietic cells, and a population of peroxidase nonreactive cells within the extravascular compartments of mouse fetal liver. The nonreactive cells were 10 μm in diameter, displayed no peroxidase activity and were designated type I cells. This cell had an irregular nucleus, small profiles of rough endoplasmic reticulum (RER), a considerable population of monoribosomes and a few polyribosomes. The incidence of this cell type decreased significantly from 50% at 12 days gestation to approximately 10% of the hemopoietic cells at 17 days gestation. Type I cells could not be classified into a hemopoietic lineage and may represent undifferentiated hemopoietic stem cells. Three forms of erythropoietic cells, designated types II, III, and IV, were identified. These cells had a diffuse cytoplasmic peroxidase reaction, no peroxidase positive membrane‐bound organelles, and were approximately 7 μm in diameter. They corresponded to the more classically defined proerythroblast, polychromatophilic erythroblast, and nucleated normoblast, respectively. Types II and III had moderate cytoplasmic reactions, whereas type III, in addition, had a slight nuclear reaction. Type IV cells had a very dense cytoplasmic reaction but no nuclear reaction. Of the myelopoietic cells detected, one form had a slightly reactive Golgi and a few reactive granules. The other form possessed a clearly positive nuclear envelope (NE), RER, Golgi, and a population of reactive granules. The phagocytic sinusoidal lining cells (Kupffer cells) were peroxidase negative in contrast to similar cells in the rat. A population of peroxidasepositive granules was detected in fetal liver developing hepatocytes at 17 days gestation and increased in number with age. The morphology and organization of these various cell types in the liver hemopoietic environment are discussed.
Insulin‐ and glucagonlike peptides in the brain
Authors: Dorn A. , Bernstein H.‐G. , Rinne A. , Ziegler M. , Hahn H.‐J. , Ansorge S.
Published: February 2005

The cellular localization and regional distribution of insulin‐and glucagonlike substance, C‐peptide‐like immunoreactivity, thiol:protein disulphide oxidoreductase, TPO (E.C.1.8.4.2.), and insulin/glucagon‐specific proteinase, ISP (E.C.3.4.22.‐), are studied in the CNS of man, adult and juvenile rats, mice, tortoises, and frogs by use of immunohistochemistry. Furthermore, the content of immunoreactive insulin, glucagon, and C‐peptide was estimated in human cadaver brains by radioimmunoassay.

It could be shown that insulinlike immunoreactive material is widely distributed in the human brain and the CNS of juvenile rats as well as in mice, whereas in the CNS of adult rats and nonmammalian animals (frog, tortoises) the polypeptide is restricted to a few nerve cell populations. C‐peptide immunoreactivity was demonstrated in human CNS in the same nerve cells as insulin.

By use of two different glucagon‐antisera it was revealed that gut‐type glucagon occurs in many nerve cells of human and mouse brains, as well as in the CNS of juvenile rats. On the other hand, pancreas‐type glucagon was less widely distributed in the human brain and nearly not detectable in the CNS of mice and rats.

With the exception of neurosecretory nerve cells, there was a high degree of coincidence between the localization of insulin and TPO. The immunoreaction against the ISP antiserum was weak, but correlated well with the distribution of insulin‐immunoreactivity.

The occurrence of TPO and ISP in the brain demonstrates the ability of nervous tissue to degrade insulin and glucagon. By radioimmunoassay it was established that human brain contains insulin, glucagon and C‐peptide at concentrations that exceed blood levels.

We conclude from our data that, at least in part, cerebral insulin and glucagon are products of the brain itself.
Effects of chronic denervation in type I cutaneous mechanoreceptors (Haarscheiben)
Authors: English Kathleen B. , Norman Dolores Kavka‐Van , Horch Kenneth
Published: February 2005

Cutaneous type I receptor sites (Haarscheiben or tactile domes) were examined at intervals of 4 to 275 days after chronic denervation of the skin. The number of domes decreased with denervation time, and only about one‐third of the domes originally present were still visible at 275 days. Most but not all of the Merkel cells from these domes were absent by 48 days, and the epithelium was significantly thinner than in nondenervated domes. Only a few of the examined domes appeared to be completely devoid of Merkel cells.

It is concluded that after nerve transection, domes degenerate but do not always disappear entirely. The remmants may thus act as target sites which either attract regenerating type I nerve fibers or facilitate the formation of new dome structures after nerve regeneration.
Lymphatic and blood vessels of the popliteal node in sheep
Authors: Heath Trevor , Brandon Roslyn
Published: February 2005

Our aim was to describe the lymphatic and blood vascular pathways to and from the popliteal lymph node in sheep. The blood vessels and lymphatics were filled with Microfil, and were cleared in methyl salicylate.

Afferent lymphatics divide and anastomose as they pass dorsally along the lateral saphenous vein, and 6–12 lymphatics reach the node. Each branches extensively on the surface of the node giving rise to 20–50 terminal afferents which enter the node over a roughly circular area. Most enter the subcapsular sinus, but some penetrate deeply into the node. Lymph leaves the node through numerous initial efferent lymphatics, many of which contain valves. These join forming progressively larger vessels, and 2–4 efferent trunks emerge from the hilus.

The hilus varies considerably in shape, depth and location, and it is filled with fat. Either a single artery, or up to 10–12 arteries derived from an anastomotic network or circle, enter the node from the hilar fat pad. Arteries may also enter at other sites. The arteries originate from the caudal femoral, or the medial circumflex femoral artery; a single node may receive blood from both arteries. This arrangement may help to maintain blood flow especially during an immune response, and despite external pressures applied to the arteries and node during movements of the animal.
Morphogenesis of motor endplates along the proximodistal axis of the mouse hindlimb
Authors: Carry Michael R. , Morita Michio , Nornes Howard O.
Published: February 2005

The morphogenesis of motor endplates along the proximodistal hindlimb axis is described for the mouse using nonspecific cholinesterase histochemistry and electron microscopy. There is a two day lag in relative stages of development between a proximal muscle (rectus femoris, RF) and a distal muscle (flexor hallucis brevis, FHB). Cholinesterase activity first appears in the RF on embryonic day 15 and the FHB on embryonic day 17. In the following days, faint wisps of reaction product thicken, form small ovals on myotubes, and finally enlarge with internal ramifications as the muscle fibers increase in diameter. Axons first enter the RF between embryonic days 12 and 13, and contact both embryonic cells (most likely myoblasts) and cells assumed to be Schwann cells. Myotubes are present in the RF the following day. The first signs of synapse formation—appearance of symmetrical electron opaque membrane patches, and dense cored and synaptic vesicles—occur between axons and myotubes in the RF on embryonic day 15. During the following days basal lamina material accumulates in the synaptic cleft, coated vesicles and postjunctional folds appear in the myotubes, and synaptic vesicles accumulate in the axon terminals. By postnatal day 42 the axon terminals lay in primary gutters opposite deep secondary postjunctional folds, and are separated and capped by Schwann cell processes.
Retention of generalized hair cell patterns in the inner ear of the primitive flatfish psettodes
Authors: Platt Christopher
Published: February 2005

Flatfish are a group of uniquely asymmetrical vertebrates, lying always on one side. This postural control depends on the vestibular receptors of the inner ear. From the most primitive living flatfish, orientations of sensory hair cells in the inner ear were mapped by scanning electron microscopy. The maps of the three otolith organs, the three semicircular cristae, and the macula neglecta (newly discovered here for flatfish) show patterns that are very similar to those in many upright teleosts, particularly perches. Thus, peripheral sensory structure does not require modification for the unusual postural control of flatfish.
Innervation of the canine thoracolumbar vertebral column
Authors: Forsythe W. B. , Ghoshal N. G.
Published: February 2005

The pattern of innervation of the caudal thoracic and cranial lumbar vertebral column of the dog is described. Frozen sections stained with Schofield's silver impregnation method show that the dorsal longitudinal ligament is profusely innervated, while the anulus fibrosus contains a few nerves limited to its outermost layers; no nerves are present in the nucleus pulposus. Following injection of horseradish peroxidase (HRP) into the anulus fibrosus of the thoracolumbar intervertebral disc and subsequent removal and staining of dorsal root ganglia, the reaction product is found in ganglia as far as two segments cranially as well as caudally, demonstrating that the disc is innervated by nerves arising from several spinal cord segments. A meningeal ramus, which innervates the discs of man, could not be found by gross dissection. Dissections show each vertebral articular facet innervated by the medial branches of two contiguous spinal nerves, a pattern further confirmed by injections of HRP into facet joints with subsequent staining of dorsal root ganglia. The dorsal rami of spinal nerves often divide into medial, intermediate, and lateral branches rather than the traditionally described division into only medial and lateral branches.
Development of macrophages in the lungs of fetal rabbits, rats, and hamsters
Authors: Sorokin Sergei P. , Hoyt Richard F. , Grant Margaret M.
Published: February 2005

Fetal rabbits (days 13–32), rats (days 14–22), and hamsters (days 11–15) and selected postnatal animals were examined for pulmonary macrophages or their precursors in 2‐m̈m sections stained by PAS‐lead hematoxylin (all species), electron micrographs (rabbit and rat), and cytochemical incubations for acid phosphatase (rabbit and rat), aliesterase, and N‐acetyl glucosaminidase (rabbits). All methods revealed macrophages in perinatal specimens. The appearance and distribution of these cells were compared in the different preparations to establish the reliability of PAS‐lead hematoxylin for identifying them in less developed fetal lungs, where they are less active for lysosomal enzymes the earlier the stage examined. In the sections, macrophages are seen to possess a round or indented nucleus, an irregular contour, and a deep purplish‐gray cytoplasm containing a variety of pink PAS‐stained granules, equated with heterolysosomes by ultrastructural cytochemistry. In less developed lungs, macrophages occur along with putative precursors having a more rounded outline and fewer PAS‐stained granules. In pseudoglandular lungs these precursors predominate over rather vacuolated macrophages resembling Hofbauer cells. In all three species both cell types first appear in the stroma during the bronchial bud stage and are frequently seen to divide from that time on. The earliest precursors have a relatively sparse cytoplasm which later increases in daughter cells. Hofbauer‐like cells disappear during the canalicular stage of development, replaced by macrophages and transitional forms from the more rounded precursors. In day 21 rabbit lungs, scattered stromal cells are reactive for aliesterase, and, some days later, for acid phosphatase and glucosaminidase. Free mononuclear cells are rare in airways of pseudoglandular lungs but become common later. A day or two before birth in rats, free cells range between rather undifferentiated leukocytes to typical macrophages, but cells with the macrophage's complete repertory of inclusions are seen only after birth. In the fetus, typical monocytes were not identified in either the pulmonary stroma or the airways. A replicating population of macrophage‐like cells therefore resides in fetal lungs. It is established before bone marrow is formed and, in rats, before monocytes have appeared in the circulation.
The mechanisms of cell death and phagocytosis in the early chick lens morphogenesis: A scanning electron microscopy and cytochemical approach
Authors: Garcí‐Porrero Juan A. , Colvée Elvira , Ojeda José L.
Published: February 2005

The cell surface characteristics of degenerating cells and phagocytes, as well as the participation of lysosomes in the cell death process associated with the early embryogenesis of chick lens rudiment, were studied by means of scanning electron microscopy and cytochemically using the Gomori‐b̃‐glycerophosphate method for acid phosphatase.

The prospective dying columnar epithelial cells lose their apical and basal processes and become rounded. The rounded, isolated, dying cells initially show a rough surface with some cytoplasmic constrictions followed by progressive break‐up into several pitted fragments. Coincident with the loss of the columnar cell shape, acid phosphatase is localized within the Golgi apparatus and autophagic vacuoles which progressively increase in size. In contrast, the isolated dying cells and fragments do not show significant acid phosphatase activity. The role of lysosomes in this degenerative process is discussed.

Neighboring epithelial cells phagocytose the dead cell fragments, becoming nonspecialized phagocytes. These consist of columnar epithelial cells and free cells which have migrated from the lens epithelium. Two mechanisms of internalization are observed. The most frequent mechanism takes place in both the columnar epithelial cells and the free cells, and consists of the progressive engulfment of the fragments into craters of the cell surface. The other mechanism is only detected in the free cells and takes place by pseudopod engulfment. We suggest that both phagocytic procedures could be related to the degree of intercellular connection. The presence of phagocytic internalization by crater formation in the epithelial cells could be a mechanism preserving the epithelial stability, which is necessary for a normal morphogenesis. Small microprocesses binding the surface of the phagocyte and the fragment are present prior to the internalization process.

In the lens stalk and in the space located between the ectoderm and the lens vesicle, there are some cells displaying migratory characteristics. This fact suggests that an active migration of epithelial cells from the lens stalk could account for the process of detachment of lens vesicle from the ectoderm. The free cells appear to undergo an in situ progressive degeneration.
Binding of secreted glycoproteins to spermatozoa in the mammalian epididymis: A fine‐structure autoradiographic study
Authors: Kopečný V. , Fléchon J.‐E. , Pivko J.
Published: February 2005

Mouse and guinea pig epididymal tissues have been investigated by light and electron microscopic autoradiography after long intervals ranging from 24 h to 5 days postinjection (p.i.) of the glycoprotein precursors, L‐fucose‐6‐3H of D‐glucosamine‐1‐3H. Using modified fixations to enhance glcoprotein preservation in situ, we found intense labelling of luminal contents in at least some of the epididymal segments after all the intervals investigated. At 24 h p.i., the label in guinea pig was associated with spermatozoa during remodelling of the acrosome in segment II, and at 3 days p.i., radioactivity was trapped within sperm head associations (“rouleaux”) in segment IV of the epididymis. At this time, similar rouleau labelling extended from segment IV to segment VIII. In mouse, the luminal contents of the cauda epididymis were still intensely labelled at 5 days p.i.; analysis of the electron microscopic autoradiograms showed that relative grain concentration over the spermatozoa was twice that of the epididymal plasma. This concentration was especially elevated in the region of the sperm head. These findings taken together were interpreted as the binding of secreted epididymal glycoproteins to spermatozoa during sperm transit through the epididymis.

In contrast to luminal contents, the labelling of the epididymal epithelium was generally lower, except on the clear cells which showed more pronounced labelling than the neighboring principal cells in mouse cauda epididymis at 5 days p.i. This label probably originated from the resorption of luminal glycoproteins.
Identification system for airways in lung models: A note
Authors: Patra Amit L. , Grady Margaret A. , Miller Frederick J.
Published: February 2005

A lobar notational system for the identification of airways in the mammalian lung is presented. This system was developed to identify uniquely the location of morphometric and deposition data within a lobe as well as within the lung, and to provide for easy and efficient data reduction. In addition, this notational system can be used to identify main stems like those found in the monopodial lung, and incorporates identification of terminal bronchioles in the airway identifier. The lobar notational system is composed of a two‐character lobe code, followed by a third character identifying the branching structure as monopodial or symmetric. The fourth digit identifies the relative position of a branch within the lobe. Subsequent digits identify the airway's relative location within the branching.
Observations on uterine mast cells during early pregnancy in the vole, Microtus agrestis
Authors: Brandon Janet M. , Evans Janet E.
Published: February 2005

The vole, Microtus agrestis, was chosen for this study of mast cells during early pregnancy because this species does not show spontaneous estrous cycles. Mast cell numbers in the uterus are known to vary during the estrous cycle in some species (rat, cow, Syrian hamster). Mast cell changes during early pregnancy in the vole could not reflect hormonal changes which had occurred during a preceding estrous cycle. Mast cells in the uterus (myometrium, endometrium, and mesometrial triangle) and ear skin were examined at 0 hours (virgin, estrus) and at 24, 48, 72 and 96 hours postcoitum (p.c.). The stain used was 0.06% toluidine blue in 0.12 M Michaelis's veronal acetatehydrochloric acid buffer at pH 4.5. The number of mast of cells observed in the uterus was not significantly affected when the nondehydrating fixative used routinely (Helly's solution) was substituted by a dehydrating fixative (Carnoy's solution without chloroform). The number of mast cells in the myometrium decreased from 0 to 72 hours p.c. and increased from 72 to 96 hours p.c. There was no significant variation in mast cell numbers in the endometrium. The number of mast cells in ear skin and in the mesometrial triangle decreased from 0 to 48 hours p.c. An increase occurred from 48 to 96 hours p.c. in ear skin and from 72 to 96 hours p.c. in the mesometrium.
Tridimensional study of the deep cortex of the rat lymph node: VIII. The deep cortex units of the athymic nude rat
Authors: Sainte‐Marie G. , Peng F.‐S. , Pritchard D.
Published: February 2005

The deep cortex of the lymph node of various species actually consists of hemispherical structures, termed deep cortex “units.” Each unit is centered under an opening of an afferent lymphatic and comprises a center and a periphery. In a recent work on the nude mouse, we found that the congenital athymic state inhibits the development of the lymphocyte population in the center of the units as well as in a related area of peripheral cortex, and that it also modifies other nodal components. In the present work, we wanted to compare the effects of the athymic state on the rat nodes. Therefore, nodes from various anatomical locations in 8‐week‐old nude rats were submitted to a tridimensional analysis. The overall effects of the congenital athymic state were found to be comparable in rats and mice. However, marked differences were noticed in the modifications of the node histology, in both species of nude animals. Their significance is discussed together with new findings.
Microvasculature of the mouse epididymis, with special reference to fenestrated capillaries localized in the initial segment
Authors: Abe Kazuhiro , Takano Hiroko , Ito Takashi
Published: February 2005

The blood supply, microvasculature, and ultrastructure of the capillaries in the epididymis in adult mice were regionally examined. The epididymal duct of the initial segment is surrounded with a dense network of fenestrated capillaries running just under the epithelium. The other segments have loose networks of nonfenestrated capillaries running in the interductal connective tissue. The fenestration of capillaries in the initial segment was markedly reduced in frequency immediately after cutting the efferent duct. In adult mice which were subjected to cutting of the efferent duct neonatally, the dense capillary network did not develop, and fenestrated capillaries were absent in the initial segment. We interpret our results to indicate that the fenestrated capillaries in the initial segment provide for absorption of the testicular fluid and that their development is dependent upon the testicular fluid entering the epididymal duct.
Descriptive studies of occlusion and reopening of the spinal canal of the early chick embryo
Authors: Schoenwolf Gary C. , Desmond Mary E.
Published: February 2005

Occlusion and reopening of the lumen of the spinal cord, two processes believed to be involved in early brain enlargement, were examined in chick embryos to determine what morphological features characterize these events. Occlusion begins at a particular craniocaudal level near the time that the neural folds become apposed in the dorsal midline and blocklike somites form from the segmental plates. During occlusion, the apical sides of the lateral walls of the neural tube are in close apposition. Interdigitating apical surface protrusions, cross‐luminal intercellular junctions, and abundant cell‐surface materials are lacking. Reopening has occurred by about stage 20 throughout most of the craniocaudal extent of the spinal cord. A lumen suddenly appears during this process, but correlated structural changes that might account for such a dramatic change in morphology were undetectable. Reopening involves the release of the forces that previously maintained occlusion, or the generation of new forces that overcome those causing occlusion, but what these forces are remains to be determined. Observations suggest that forces generated outside of the neural tube might be largely responsible for occlusion, and experiments are in progress to test this possibility.
Ovulation of ovarian implants in unilaterally ovariectomized rats
Authors: Quattropani Steven L.
Published: February 2005

Subcutaneous autografts of ovarian tissue were made in unilaterally ovariectomized adult rats and were examined by light microscopy at various times after implantation. The implants were surrounded by a dense connective tissue capsule. They were well vascularized and contained follicles in varying stages of development as well as in different stages of atresia. Oocytes and fresh corpora lutea indicated that grafts ovulated in the presence of the in situ ovary but that the number of ovulations and their frequency were reduced when compared to normal ovaries or ovaries grafted in bilaterally castrated animals. Ovulation results in the formation of a cyst that contains follicular fluid, the oocyte, and cumulus in the ovarian stroma. Macrophages are associated with the oocyte‐cumulus complex but are not prominent in association with the fluid in the cyst. It is suggested that follicular fluid is retained owing to inefficient resorption mechanisms and that this coupled with occasional ovulations results in the formation and maintenance of the large cysts.
The effects of simulated increases in body weight for 60 days on robusticity and mineral content of limb bones of hypophysectomized rats
Authors: Simon Mark R. , Holmes Kenneth R. , Olsen Aart M.
Published: February 2005

The purpose of this investigation was to subject separate male and female groups of weanling hypophysectomized rats each to a specific 10% simulated increase in body weight using constant centrifugation, ranging from 1.1G to 2.0G, to study changes in bone robusticity and bone mineral content. (In this paper, “G” is the acceleration due to gravity.) After 60 days of centrifugation at 24 rpm, the rats were killed and the humerus, radius, ulna, femur, and tibia were removed, cleared of soft tissues, weighed, measured, decalcified with EDTA, and reweighed. Bone robusticity was determined using the ponderal index: P.I. = bone length ÷ \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt[3]{{{\rm bone}\,{\rm weight}}} $\end{document}; and bone mineral content (BMC) was determined using the formula: BMC = [(Wu – Wd) ÷ Wu] × 100. Tukey's Studentized Multiple Range T Test was used. The data suggest that, for both male and female hypophysectomized rats, bone robusticity is decreased with simulated increases in body weight; also, for males, a bimodal curve describing the relationship between BMC and simulated increases in body weight is suggested.
A method for the preparation of large intact sheets of intestinal mucosa: Application to the study of mouse aggregation chimeras
Authors: Schmidt Günter H. , Wilkinson Maureen M. , Ponder B. A. J.
Published: February 2005

A technique for the preparation of entire intestinal mucosal sheets is described that renders the population of crypts accessible for two‐dimensional study. We have applied the technique to demonstrate the mosaic crypt populations in the intestinal epithelium of mouse aggregation chimeras, using the lectin Dolichos biflorus agglutinin (DBA) as a strain‐specific histochemical marker.
Further evidence of inactivity of hypothalamo‐pituitary‐thyroid axis in snell dwarf mice
Authors: Lewiński Andrzej , Bartke Andrzej , Kovacs Kalman , Richardson Lyn , Smith Nancy K. R.
Published: February 2005

The effects of hemithyroidectomy (hemiTX) and complete thyroidectomy (TX) on the cellular composition and the mitotic activity of the anterior pituitary gland were examined in genetically thyrotropin (TSH)‐deficient female Snell dwarf mice (dw/dw) and in phenotypically normal female mice (?/+) from the same strain. In normal (nondwarf) mice, both hemiTX and TX reduced the percentage of acidophilic (orange G‐positive) cells and increased the percentage of thyrotropic (aldehyde fuchsin [AF]‐positive) cells, whereas the percentage of gonadotrophs (PAS‐positive cells) and chromophobes (unstained cells) was not affected. Both interventions increased the mean mitotic activity rate (MMAR) of the anterior pituitary lobe. This effect was related to the enhancement of the MMAR of acidophilic cells and, particularly, thyrotropic cells. The MMAR of thyrotrophs in thyroidectomized normal mice was significantly higher than that in sham‐TX controls or in hemithyroidectomized animals.

In Snell dwarf mice, neither hemiTX nor TX affected the percentage of the various cell categories (PAS‐positive, unstained, and extremely rare AF‐positive cells) in the anterior pituitary lobe. Furthermore, neither hemiTX nor TX substantially influenced the MMAR of the gland. No mitotic figures were found in the AF‐positive cells. Since the AF‐positive cells in the anterior pituitary of dwarf mice completely failed to respond to hemiTX or TX, we believe they are not true thyrotropic cells.

Using electron microscopy, we confirmed a lack of somatotrophs, mammotrophs, and normal thyrotrophs in the anterior pituitary of Snell dwarf mice. The results provide morphological evidence of inactivity of the hypothalamo‐pituitary‐thyroid axis in Snell dwarf mice.
Resistance vessels supplying the median eminence of the rabbit, rat, and cat
Authors: Page Robert B. , Dovey‐Hartman Barbara J.
Published: February 2005

The ultrastructure of arterioles supplying the median eminence of eight rats, eight rabbits, and two cats was studied after vascular perfusion with phosphate buffered aldehyde fixatives. There were terminal arterioles with a lumen diameter of 50–70 μm within the pars tuberalis. Smaller arterioles (precapillary sphincters and metarterioles) with a lumen diameter of 15–20 μm were present on the surface of the median eminence. Arterioles were not observed to penetrate the neuropil but were seen to supply the external capillary plexus of the median eminence. Direct innervation of arterioles supplying the median eminence was not present and hence regulation of median eminence blood flow by peripheral sympathetic mechanisms appears unlikely. Resistance vessels were found to be closely related to axon terminals on the surface of the median eminence and to fenestrated capillaries of the external plexus. In addition, the endothelial cells of arterioles were characterized by the presence of pits and vesicles which may play a role in transendothelial transport. These findings suggest two mechanisms by which blood flow into the median eminence can be regulated: (a) by central catecholaminergic systems terminating in the median eminence and (b) by catecholamine secretions from the adrenal medulla.
Distribution of lectin binding sites in rabbit oviduct
Authors: Menghi Giovanna , Maria Bondi Anna , Materazzi Giovanni
Published: February 2005

The carbohydrate histochemistry of the rabbit oviduct has been examined by the use of four lectins conjugated with horseradish peroxidase as histochemical reagents. Each lectin gave a very distinct typical pattern of binding, but for each lectin there was no difference between the distribution of binding sites in ampulla and isthmus. Wheat germ lectin bound exclusively with the connective tissue of the oviduct folds; winged pea lectin was detected only in the ciliated cells; peanut lectin binding sites were visualized in the secretory cells; the binding reactivity of soybean lectin was limited to the basal part of the cilia. Although it is very difficult at present to correlate the distribution of lectin binding sites with the function of the positive cells, some hypotheses have been advanced.
Effects of hormones and gonadal status on the midventral gland of the grasshopper mouse Onychomys leucogaster
Authors: Pinter Aelita J.
Published: February 2005

A midventrally located fusiform sebaceous gland is found in the northern grasshopper mouse Onychomys leucogaster. Microscopically, the gland consists of numerous multilobular units. Copious secretory material collects in the central duct of each unit and is extruded to the outside. The gland is larger in the male than in the female. Castration causes an involution of the gland in both sexes. Testosterone propionate (1.0 mg/0.1 cc olive oil, subcutaneously every other day for 4 weeks) restores the gland to full activity in castrates of both sexes. Estradiol benzoate (0.1 mg/0.1 cc olive oil, subcutaneously every other day for 4 weeks) has no effect on the midventral gland of ovariectomized females. A long photoperiod (18 L/6 D) leads to the development of testes, ovaries, and uteri that are significantly heavier than those of animals from a short photoperiod (6 L/18 D) regime. Midventral glands in animals of both sexes from the long photoperiod are larger and more active than glands of animals from the short photoperiod. The secretions of the midventral gland of Onychomys are probably used for communications such as territorial marking, advertisement of gonadal status, or pup identification.
Epidermal and papillary dermal characteristics of the bowhead whale (balaena mysticetus)
Authors: Haldiman Jerrold T. , Henk William G. , Henry Robert W. , Albert Thomas F. , Abdelbaki Yahya Z. , Duffield Dennis W.
Published: February 2005

Skin samples from most body regions of the bowhead whale were examined. The epidermis is 2.7 to 50 times thicker than that reported in other cetaceans with both regional and individual variations in thickness. The thinnest areas examined (1 mm) occur on the eyelid margins and the thickest (25 mm) occur on the lower jaw. A distinctive parakeratotic stratuim corneum with a thick underlying stratum spinosum (without a stratum granulosum) extgends over the entire body surface. From a few dozen to several hundred epidermal lesions are present on all whales studied. A typical stratum basale of germinative keratinocytes (with melanocytes in pigmented areas) rests upon a well‐defined basal lamina. Epidermal rod arrays arise from the basal keratinocytes which cover highly elongated dermal papillae and extend to the epidermal surface through the distal stratum spinosum and the stratum corneum. At least four diatom genera occur on and in the stratum corneum and lesion areas of different whales. The superficial dermis consists of a papillary layer with long (up to 13 mm) dermal papillae interdigitating with the epidermis from a basal area that is 2–4 mm in thickness. The number of dermal papillae per mm2 varies inversely with the thickness of the epidermis. Large diameter, sensory papillae packed with tortuous, highly elongated, encapsulated nerve end organs also interdigitate with the thin epidermal areas of the ventral surface of the rostrum, the upper and lower lip margins, and the upper and lower eyelid margins. Scattered, single, stiff hairs emerge from the skin only in specific, pigmented regions of the head.
Light and electron microscopy of the new born sagittal suture
Authors: Decker Jay D. , Hall Stanton H.
Published: February 2005

Morphogenesis and maturation of the sagittal suture in newborn C57B1/6J strain mice were studied using light and electron microscopy. Morphodifferentiation of the murine parietal bones progresses radially with the interposed sagittal suture, assuming a greater level of maturity at birth at a midpoint along its length. The presumptive suture develops in a sulcus, deeper posteriorly, more shallow anteriorly. Cells at the osteogenic front (OF) are distinguished from the surrounding fibrocytic cells by a number of distinctive characteristics: 1. increased cytoplasmic density; 2. extensive endoplasmic reticulum; 3. dispersed nuclear chromatin aggregates; 4. extensive surface projections; 5. close approximation.

Mineralization of the developing parietal bone occurs extracellularly with the initial deposits of apatite crystals exhibiting no oriented relationship to either cellular or extracellular fibrillar elements.

The majority of collagen fibers lie superior and inferior to the presumptive suture, oriented anteroposteriorly with their long axes parallel to the ectocranial surface. Other fiber bundles more intimately associated with the developing suture display a more random orientation.
1,25‐dihydroxyvitamin D3 in teeth of rats and humans: Receptors and nuclear localization
Authors: Clark S. A. , Dame M. C. , Kim Y. S. , Stumpf W. E. , DeLuca H. F.
Published: February 2005

Autoradiographic and biochemical studies were used to demonstrate 1,25 (OH)2 vitamin D3 target cells in teeth. Incisor pulp of rats and molar pulp of humans were incubated in vitro with 3H‐1,25 (OH)2 vitamin D3. Subsequent frozen‐section autoradiography revealed a large population of cells in the pulp of both incisors and molars which selectively concentrated radioactivity in their nuclei. Extracts of incisor pulp from mature rats were found to bind 3H‐1,25 (OH)2 vitamin D3 and this binding was displaceable with excess 1,25 (OH)2 vitamin D3. Sucrose density analysis revealed that the protein in tooth pulp which binds 1,25 (OH)2 vitamin D3 sediments at 3.2–3.5S. The 1,25 (OH)2 vitamin D3 receptor of intestine and kidney also sediments in this region, indicating that the 1,25 (OH)2 vitamin D3 binding protein of tooth pulp is similar to that found in other target organs. These autoradiographic and biochemical data indicate that pulpal cells of mature rat and human teeth contain receptors for 1,25 (OH)2 vitamin D3.