bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphometric analysis of capillary geometry in pigeon pectoralis muscle
Authors: Mathieu‐Costello Odile
Published: February 2005

The objective of the study was to examine the relationship(s) between the size and the geometry of the capillary network in the flight muscle of pigeon (Columbia livia). To this end, we used morphometry to analyze the degree of anisotropy (i.e., orientaion) of capillaries with respect to the axis of the muscle fibers in perfusion‐fixed samples of pigeon pectoralis muscles with large difference in capillary denstiy. Capillary number per fiber cross‐sectional area (range, 1,491–5,680 mm−2) depended on fiber size (aerobic fibers, 304–782 μm2; glycolytic, 1,785–2,444 μm2), as well as sarcomere length (1.69–2.20 μm), and the relative sectional area of aerobic and glycolytic fibers (aerobic, 42–84% of total fiber area). The degree of tortuosity of capillaries, i.e., their bending or sinuosity relative to the muscle fiber axis, was primarily a function of sarcomere length. In spite of large differences in capillary density, capillary orientation at a given sarcomere length was remarkably similar among samples. In addition to capillaries running parallel to the muscle fiber axis, a unique arrangement of branches running perpendicular to the muscle fiber axis was found in all samples. This arrangment yielded a large circumferential distribution of capillary surface around the muscle fibers. Compared to mammalian limb muscles examined over a 10‐fold range of capillary density (rang, 450–4,670 mm−2), the degree of anistropy of capillaries was greater in all samples of pigeon M. pectoralis. In the pigeon, there was no increase in the amount of capillary surface area available for exchange per microvessel as a result of a greater degree of capillary tortuosity in samples with larger capillary density (capillary number per fiber cross‐sectional area> 4,000 mm−2), as compared to samples with a capillary density <4,000 mm−2.
Studies of hamster cardiac myofibrillogenesis in vivo with Antibodies to spectrin, desmin, and alpha‐actinin
Authors: Messina Dino A. , Lemanski Larry F.
Published: February 2005

The spectrins are a family of cytoskeletal‐membrane proteins that have generated much interest in the past decade. In the present study, we utilized immunohistochemical, morphological, and electrophoretic techniques to assess the possible function(s) of spectrin in mammalian cardiac tissue during development. Antibodies generated against alpha‐actinin and desmin were also employed to identify myofibrils and intermediate filaments in relation to changes in the distribution of spectrin. Spectrin is localized along the sarcolemma of pre‐myofibrillar hamster cardiac myocytes (day 8, postcoitum) and remains associated with the cell membrane throughout development. The staining pattern is somewhat diffuse at first, but eventually the cell margin becomes clearly defined by day 13 postcoitum. A second, more profound change in the distribution of spectrin occurs during the newborn stage, when spectrin begins to appear in the sarcoplasm. It appears as regularly speced invaginations that are diffuse at first, eventually attaining a position around the Z‐bands of adult muscle. The change in the distribution of spectrin coincides temporally with the appearance of T‐tubules, which are sarcolmmal invaginations that reside at the Z‐bands of adult heart. Thus, spectrin may act as a guidance mechanism for the proper postioning of T‐tubules around the Z‐discs of mammalian cardiac tissue. Although spectrin does not appear to interact directly with early myofibrils it may assist in the proper alignment of T‐tubules and, in doing so, act to stabilize the entire contractile apparatus by enveloping it and attaching it to the sarcolemma.
Distribution and histochemical characterization of goblet cells in the nasal cavity of piglets
Authors: Larochelle Renée , Martineau‐Doizé Béatrice
Published: February 2005

The present study was desiged to compare the distribution of goblet cells and the histochemical composition of mucosubstances produced by these cells in the nasal cavity of piglets aged from 1 to 28 days. Serial transverse sections were stained to demonstrate neutral, acidic, and sulfated mucosubstances. Sections located at eight reference levels rostrocaudally in the nasal cavity and defined regions on these sections were used for goblet‐cell counting. There was a nonhomogeneous distribution of goblet cells in the nasal cavity of piglets. A rostrocaudal increase in goblet‐cell density was observed with the highest densities found in the ventral meatus and on the septum. There was no difference in this pattern of distribution according to age of the piglets. However, age‐related differences were observed in the prevalence of goblet cells containing sialomucins, sulfomucins, or both. While sialomucins were prevalent at 1 and 14 days, sulfomucins predominated in the rostral half of the cavity at 28 days. Our results indicate a maturation of the products of secretion with aging in piglets. The affinity of infectious agents for sialylated glycoconjugates and the predominance of sialomucins in the nasal cavity of newborn piglets could account for their greater susceptibility to bacterial infection.
The sinoatrial ring bundle: A cardiac neural communication system?
Authors: Roberts L. A.
Published: February 2005

The sinoatrial ring bundle (SARB). was originally described as a “whitish bundle of tissue which describes an almost complete loop around the two venae cavae and the coronary sinus” in the adult rabbit heart (Paes de Carvalho et al., 1959). The histologically and electrophysiologically differentiated structure, derived from the embryonic venous valves, was suitably placed for rapid conduction from sinoatrial (SA) to atrioventricular (AV) node, but no evidence was found for this role. Today, the function of the SARB remains obscure. Cholinesterase/silver staining reveals the neural pattern associated with the SARB and suggests a function. Throughout its extent, the SARB contains a bundle of parallel muscle fibers and accompanying long nerves. The nerves distribute to structures at either side of the loop: superolaterally to pectinate muscle and inferomedially to the region of the AV node. Along the curve of the right SARB, the nerves contribute to a dense neural plexus with nerves coiled around muscle. The plexus communicates with the nearby SA node and with the ganglia inferior to the node near the inferior vena cava. The morphological pattern of neural elements is suitably organized to suggest tension monitoring and internodal, neural communication.
Auditory epithelial migration. III. development of the stratified squamous epithelium of the tympanic membrane and external canal in the mouse
Authors: Michaels Leslie , Soucek Sava
Published: February 2005

The development of the stratified squamous epithelium of the tympanic membrane and external auditory canal was studied in serial sections of 124 mouse ears aged from 11 gestational days to 100 days. A fold developed from the edge of the fundus of the primary canal. It possessed two regions: firstly the meatal plate, which produced the pars tensa‐covering epithelium (zone 2) and most of the deep ear canal epithelium (zone 3), and secondly the fundal extension plate, which grew from that part of the fundus not forming the meatal plate. The fundal extension plate gave rise to the pars flaccida‐covering epithelium (zone 1) and also to the adjacent deep canal epithelium (zone 3). A difference from human development was that zone 3 in the mouse, in both the meatal plate‐and the fundal extension plate‐derived areas, formed adnexal structures. In the early development of the meatal plate, zone 3, at its tip, was swollen and actively mitotic and extended always for a short distance on to the zone 2 side. Zone 2, first perceived two days after zone 3, became progressively attenuated, and by the fourth day after its formation was a single thin layer. It is suggested that the proximal part of zone 3, situated in the mature ear around the periphery of the tympanic membrane, is a generation center for unidirectional outward flux of epithelium which terminates in the mouse at the first adnexal structure. It may cause the whole of zone 2 to move in the same direction by negative contact inhibition.
An immunohistochemical study of the GnRH neuron morphology and topography in the adult female rabbit hypothalamus
Authors: Foster Warren G. , Younglai Edward V.
Published: February 2005

The morphology and distribution of immunoreactive (GnRH) neural elements in the hypothalamus of the adult nulliparous female rabbit were examined. Approximately 1,000 GnRH cells (range 890‐1136) were counted in the right half of the hypothalamus. Two distinct GnRH cell types were observed: GnRH cells with rough or spiny contours accounted for 64% of the total immunoreactive cells, and smooth‐contoured cells represented 34% of the total. The majority of immunoreactive neural elements were found in the anterior hypothalamus. GnRH cells and processes were located primarily in the ventral and medial anterior hypothalamus forming an inverted V pattern. Processes were followed from the medial preoptic area and suprachiasmatic nucleus to the infundibular stem. Extrahypothalamic projections of GnRH cells were observed. Immunoreactive fibers were also found to contact the ependymal lining of the third ventricle. It is concluded that two morphologically distinct GnRH cell types exist and have a broad distribution in the rabbit hypothalamus. The functinal significance of these cell types requires further study.
Immunological mutants of the mouse
Authors: Shultz Leonard D.
Published: February 2005

Mutations at more than 30 loci in mice have been shown to cause deleterious effects on the immune system. Immunologic defects caused by certain of these mutations are determined at the level of hematopoietic progenitor cells or at the level of hematopoietic cell‐stromal cell interactions. The immunological mutants described in this paper serve as experimental tools with which to increase our understanding of the development and regulation of the mammalian immune system.
Sequence‐specific binding of a c‐myc nuclear‐matrix‐associated region shows increased nuclear matrix retention after leukemic cell (HL‐60) differentiation
Authors: Chou Robin H. , Churchill Judy Rae , Mapstone Diane E. , Flubacher Marcella M.
Published: February 2005

HL‐60 cells, a human promyelocytic leukemia cell line, contain amplified c‐myc DNA sequences and mRNA transcripts. These cells can be induced to undergo macrophage differentiation by phorbol esters, which results in suppression of c‐myc expression and cessation of cell proliferation. The nuclear matrix (NM), a nuclear skeleton resistant to DNase I digestion and high salt extraction, is proposed to be involved in DNA replication, gene regulation, and the correct distribution of DNA at mitosis. We have previously identified a nuclear‐matrix‐associated region (MAR) of the c‐myc protooncogene to reside in a 1.4‐kb region between Cla I and Eco RI restriction sites at the 3′‐end of the gene. A 172‐bp Dra I/Dra I subfragment of the 1.4‐kb region was shown to be a major component of the MAR (myc‐MAE), and this subfragment was demonstrated to be recognized by a nuclear protein (p25). In this report we demonstrate that ϕX174 DNA, or the synthetic copolymers poly[d(G·C)] and poly[d(A·T)], are not effective suppressors of the binding of the myc‐MAR to isolated NM, indicating that the binding sequence(s) are unique. We find that the addition of partially purified protein p25 increases the relative affinity of the myc‐MAR for HL‐60 NM in an in vitro assay system. NM isolated from HL‐60 macrophages induced by phorbol esters retains significantly more myc‐MAR DNA fragment in the presence of an excess amount of competitor DNA than does NM from untreated HL‐60 cells. These data suggest that a change of the myc‐MAR association with the NM occurs after monocytic differentiation of HL‐60 cells.
Bone marrow‐thymus axis in senescence
Authors: McCormick Kevin R. , Haar Jack L.
Published: February 2005

This presentation offers a brief review of the bone marrow‐thymus axis in senescence, a putatitive model for thymocyte differentiation, and recent results of our work on the status of pre‐thymic stem cells in aged mice. The data presented here provide further evidence for a thymus endocrine influence on the bone marrow stem cells, specifically lymphocyte precursors. It has been pstulated that the thymic hormones may act on lymphocyte precursors in the bone marrow and that the loss of thymic factors during senescence may be a contributing factor to the decreased cellular immune function. This study used Haar's in vitro model to investigate the bone marrow‐thymus axis in aged mice. Erythroid‐depleted bone‐marrow cells from 3‐month‐ and 24‐month‐old CBA (Thy 1.2) mice were placed in the upper half of a blind‐well chamber with thymus supernatant in the lower half. Experimental cells were treated with thymus supernatant for 1 hr prior to migration. This study confirmed that pre‐thymic stem cells in aged bone marrow are deficient in their ability to migrate to the thymus supernatant. It also revealed that treatment of the old bone marrow with thymus supernatant, made from neonatal thymus cultures, could dramatically improve the thymus migrating ability of the aged bone‐marrow stem cells.
Ultrastructural and morphometric analysis of the separation of two thigh muscles in the chick
Authors: Schroeter Sally , Tosney Kathryn W.
Published: February 2005

Limb muscles separate from one another in a complex but highly stereotyped sequence and spatial pattern. The process of separation is characterized by the progression of a region of increased extracellular space, the cleavage zone, along the proximodistal axis between the individual muscle anlagen. We analyzed ultrastructurally the muscles and cleavage zone during the separation of two representative muscles, the developing sartorius and iliotibialis in the chick thigh, to establish an accurate baseline for an analysis of the mechanisms of separation. Comparisons of the morphology and distribution of cells before and after separation show no evidence that muscles became separated by the massive influx of an exterior cell population; if populations invade the cleavage zone, they are small. We do find characteristic transitions within the cell population of the cleavage zone in situ that could accomplish cleavage without invoking massive cell movements. These progressive transitions within the cleavage zone include a loss of close cell‐cell interactions, an increase in extracellular space, the assumption of a more stellate morphology by mesenchyme cells, and a gradual alteration in the composition of the extracellular matrix from one typical of early muscle to one typical of loose connective tissue. Myotubes do differentiate between the incipient muscles, ruling out the possibility that the location where muscles will separate is defined by sites where myotubes fail to differentiate. Instead, the myotubes in the cleavage zone gradually diminish in number and appear to be specifically recognized and removed from the cleavage zone by phagocytes. We suggest that the transitions within the cleavage zone, including the loss of muscle cells, are a result of the progressive differentiation of loose connective tissue. If so, then the spatial pattern and process of cleavage is a consequence of spatially programmed cell differentiation.
Lumbar lateral motor columns and hindlimbs of two Xenopus laevis chromosome mosaics
Authors: Sperry David G.
Published: February 2005

Two chromosome mosaic Xenopus laevis, one tadpole and one metamorphic animal, both with different sizes of neurons on the left and right sides of their brains and spinal cords, have left and right lumbar lateral motor columns (L‐LMCs) of equal lengths but composed of strikingly different numbers of motoneurons (40% fewer motoneurons on the side composed of larger cells). One portion of the lumbar cord in the metamorphic animal is bilaterally symmetrical; the cells on both sides are small and the numbers of motoneurons per section are the same. The mosaics demonstrate that column length and motoneuron density (number per section) are, or can be, regulated bilaterally and that changing cell size affects factors controlling cell density but not column length. Except for the peripheral nerves, there is no evidence of any side‐to‐side differences in the hindlimb tissues. Whether the side‐to‐side difference in L‐LMC motoneuron number in the stage 66 mosaic corresponds to any feature of the hindlimbs is unknown, but similar side‐to‐side differences in an early and a late stage mosaic animal support the idea that whatever creates the initial number may also determine the final number of motoneurons.
New aspects of the morphology and function of the human hip joint ligaments
Authors: Fuss Franz K. , Bacher Andreas
Published: February 2005

The capsular ligaments of the human hip joint were submitted to exact morphological analysis, and they proved to be multiple and numerous. We have described various ligamentous systems and their interconnections, and have suggested new terminologies and systematics. The ligaments were subjected to functional analysis by means of measuring strips to determine the positions in which the ligaments are taut. The ligament systems were all found to serve a restrictive function, and various parts of the apparatus restricted all possible movements in the hip joint. Extension is restricted by the medial iliofemoral complex, abduction by the pubofemoral ligament, and adduction by the posterior coxal ligaments and by the superior ischiofemoral ligament. Flexion is restricted by the inferior ischiofemoral ligaments, inward rotation by the superior ischiofemoral ligament, and outward rotation by the lateral iliofemoral complex. Only the ligament of the femoral head is unable to exert a restricting function, despite reaching a state of tension in extreme adduction.
Electron microscopic and histochemical studies of the mononuclear osteoclast of the mouse
Authors: Domon Takanori , Wakita Minoru
Published: February 2005

Osteoclasts collected from the long bones of mice were cultured on dentin slices. To identify osteoclasts, the tartrate‐resistant acid phosphatase (TRACPase) activity of cultured cells was histochemically examined by the azo dye method. The TRACPase‐positive cells could be distinguished from other cells by light microscopy. The cells were sectioned by alternating semithin and ultrathin sections to observe their ultrastructure and three‐dimensional structure.

TRACPase activity was detected both in multinucleated osteoclasts and in mononuclear cells. Most of the mononuclear TRACPase‐positive cells had features similar to preosteoclasts. A mononuclear TRACPase‐positive cell was a ruffled border and clear zone was reconstructed three‐dimensionally by NIKON COSMOZONE 2SA. The reconstruction showed that this cell possessed a large clear zone and small ruffled border. Under the ruffled border, no lacuna was apparent; but there was disruption of the dentin surface. The results suggest that this cell was a mononuclear osteoclast and that it might have been in the process of making a new lacuna.
Morphological and histochemical comparison of the cells elicited by ectopic bone implants and tibial osteoclasts
Authors: Kelly Janet Dvonch , Schneider Gary B.
Published: February 2005

Pellets of mineralized and demineralized bone and a composite mixture of mineralized and demineralized, devitalized bone particles were implanted subcutaneously on the dorsal body wall of young adult rats. Two weeks post‐implantation, the pellets were removed and processed for histochemical and morphological analyses. Rat proximal tibia was also processed for evaluation. The levels of tartrate‐resistant acid phosphatase (TRAP) activity in the multinucleated giant cells (MNGCs) from each of the three implants and from osteoclasts were assessed using an image analyzer. The osteoclasts from the proximal tibia and the majority of MNGCs from the demineralized implants demonstrated high levels of TRAP activity. MNGCs from the mineralized implants showed either a low level or absence of TRAP activity. Most MNGCs from the composite implants exhibited a low level of TRAP activity; however, there was a population of cells that demonstrated a high level of reaction product, similar to that seen in the tibia and demineralized implant. Morphologically, osteoclasts from the proximal tibia and from the osteogenic demineralized implant exhibited ruffled borders. A small population of MNGCs from the composite implant also revealed osteoclastic features. In summary, MNGCs from the mineralized implant did not exhibit a level of TRAP reaction product or morphology similar to osteoclasts, while the majority of cells from the demineralized implant and a subpopulation of the MNGCs elicited by the composite implant did demonstrate TRAP expression and morphology similar to osteoclasts. The expression of osteoclastic characteristics in cells at an ectopic site may be dependent on accessory signals from the skeletal microenvironment; such signals appear to be absent from or incomplete in the mineralized implants but appear to be present when demineralized bone particles are implanted.
Genesis of hadacidin‐induced cleft palate in hamster: Morphogenesis, electron microscopy, and determination of DNA synthesis, cAMP, and enzyme acid phosphatase
Authors: Shah Ravindra M. , Schuing Ruth , Benkhaial Gheith , Young Alan V. , Burdett David
Published: February 2005

A morphological, electron microscopic, and biochemical study was undertaken to analyze the genesis of hadacidin‐induced cleft palate in hamster fetuses. Gross and light microscopic observations indicated that hadacidin affected the growth of vertical palatal shelves to induce cleft palate. Electron microscopic observations showed that initial hadacidin‐induced changes were seen in the mesenchymal cells. Within 12 hr of drug administration, the perinuclear space was swollen and a lysosomal response injury was evident in the mesenchymal cells. Subsequently, 24 hr after hadacidin treatment, lysosomes appeared in the epithelial cells; changes were also seen in the basal lamina which included separation of the lamina densa from the basal cells, duplication of lamina densa, and complete loss of basal lamina. Between 36 and 42 hr post‐treatment, the cellular and basal lamina changes subsided, and the epithelium of vertical shelves underwent stratification. Biochemical determination of enzyme acid phosphatase indicated that the levels of enzyme activity in both the control and treated palatal tissues corresponded to the appearance of lysosomes. Measurement of cAMP levels suggested that the peak activity of cAMP corresponded to that of enzyme acid phosphatase and cell injury. The cAMP activity in hadacidin‐injured cells, however, was significantly lower in comparison to that of the dying cells of control palates. Hadacidin treatment also affected DNA synthesis in the developing primordia of the palate. It was suggested that hadacidin injures the precursor cells of the palate prior to the appearance of the primordia, and subsequently affects their proliferative behavior, stunting the vertical growth of the palatal shelves and inducing a cleft palate.
Ultrastructure of palatal taste buds in the perihatching chick
Authors: Ganchrow Donald , Ganchrow Judith R. , Goldstein Ronald S.
Published: February 2005

Palatal taste buds of perihatching chicks were examined by electron microscopy. Four intragemmal cell types were characterized.

(1) Light: with voluminous, electron‐lucent cytoplasm containing scattered free ribosomes, rough and smooth endoplasmic reticulum, plump mitochondria, sparse perinuclear filaments, occasional Golgi bodies, and numerous clear and dense‐cored vesicles. Clear vesicles sometimes aggregate in a presynaptic‐like configuration apposed to an axonal profile. These cells contained large, spherical, uniformly granular nuclei with one nucleolus. (2) Dark: with dense cytoplasm containing filamentous bundles surrounding the nucleus, occasional clear vesicles, centrioles, rough endoplasmic reticulum, and compact mitochrondria. The apical cytoplasm noticeably lacks dense secretory granules. Irregular to lobulated nuclei are densely granular, and contain scattered clumps of chromatin, adhering especially to the inner leaflet of the nuclear membrane, and at least one nucleolus. Cytoplasmic extensions of dark cells envelop other intragemmal cell types and nerve fibers. Light and dark cells project microvilli into the taste pore. (3) Intermediate: contain gradations of features of light and dark cells. (4) Basal: darker than the other intragemmal cell types and confined to the ventral bud region. Putative afferent synapses in relation to light cells, and axo‐axonal contacts are described. While the appearance of axo‐axonal contacts may be a transient developmental event, other bud features are consonant with observations in adult chickens and suggest that the peripheral gustatory apparatus is mature at hatching in this precocial avian species.
Temporospatial study of the migration and distribution of cardiac neural crest in quail‐chick chimeras
Authors: Miyagawa‐Tomita Sachiko , Waldo Karen , Tomita Hitoshi , Kirby Margaret L.
Published: February 2005

It has been demonstrated that the septation of the outflow tract of the heart is formed by the cardiac neural crest. Ablation of this region of the neural crest prior to its migration from the neural fold results in anomalies of the outflow and inflow tracts of the heart and the aortic arch arteries. The objective of this study was to examine the migration and distribution of these neural crest cells from the pharyngeal arches into the outflow region of the heart during avian embryonic development. Chimeras were constructed in which each region of the premigratory cardiac neural crest from quail embryos was implanted into the corresponding area in chick embryos. The transplantations were done unilaterally on each side and bilaterally. The quail‐chick chimeras were sacrificed between Hamburger‐Hamilton stages 18 and 25, and the pharyngeal region and outflow tract were examined in serial paraffin sections to determine the distribution pattern of quail cells at each stage. The neural crest cells derived from the presumptive arch 3 and 4 regions of the neuraxis occupied mainly pharyngeal arches 3 and 4 respectively, although minor populations could be seen in pharyngeal arches 2 and 6. The neural crest cells migrating from the presumptive arch 6 region were seen mainly in pharyngeal arch 6, but they also populated pharyngeal arches 3 and 4. Clusters of quail neural crest cells were found in the distal outflow tract at stage 23.
Pigment cell localizations in anuran ventral skin at climactic metamorphosis
Authors: Denèfle Jean‐Pierre , Lechaire Jean‐Pierre
Published: February 2005

In anuran amphibians, the specific color pattern of the skin is expressed after metamorphosis, and its formation involves pigment cell migrations. Pigment cells are differently distributed in the tadpole, larval, and froglet skin. To learn more about their fate during metamorphic climax and in the young froglet, we focused our attention on the different localizations of larval melanophores and iridophores in the ventral skin of Rana esculenta before and during skin homing. Localizations of melanophores and iridophores can be elucidated at the developmental stages suggested by Taylor and Kollros (TK stages).

At TK stage II (during early premetamorphosis), large melanophores beneath the larval skin are detected. At TK stage X, dispersed melanophores lie under bundles of muscular striated fibrils near the larval skin; they are also observed at the vascular level. At TK stage XVII (prometamorphosis), melanophores are extended on the inner side of the basement lamellar collagen. At the end of prometamorphosis, iridophores are located with melanophores in the separating space between attached basement collagen and derived basement collagen. At TK stage XX (earlier climax), melanophores and iridophores are detected inside the upper extremities of fractures opened in the derived basement collagen. At TK stage XXIV (later climax), both types of larval pigment cells are observed in the inner extremities of breaks derived from the fractures. During climax, these pigment cells occupy the well‐formed breaks. At TK stage XXV in young froglet, the pigment cells remain alone in the breaks formed in the derived basement collagen.

Briefly, breaks in the basement lamellar collagen are opened by invading cell processes of mesenchymal cells. The cells move through the fractures toward the epidermis, followed in later stages by melanophores and iridophores.
Clonal development of interconnected germ cells in the rat and its relationship to the segmental and subsegmental organization of spermatogenesis
Authors: Ren Hong Ping , Russell Lonnie D.
Published: February 2005

Segments and subsegments are the smallest unit of synchrony thus far described within longitudinal sections of seminiferous tubules. It is known that cells in a clone joined by intercellular bridges are at the same phase of development and are also thought to be units of synchrony. This study was designed to determine if it is possible that the synchrony seen in cells joined by intercellular bridges is the same as that cataloged along the long axis of the seminiferous tubule. In the present study, the maximum number of rat spermatids joined by intercellular bridges (a clone) was obtained. It was hypothesized that if the clone size were larger than the smallest known units of synchrony (segments or subsegments) in the long axis of the seminiferous tubule, then intercellular bridges would most likely govern the synchronous development of segments or subsegments (or finer subdivisions thereof). If the clone size is smaller than the number of cells present in a segment or subsegment, then other factors must govern synchrony in the longitudinal aspect of the tubule. In the determination of spermatid clone size, rat testes were injected with cytochalasin D which opens intercellular bridges of a spermatid clone to produce large symplasts. The number of nuclei in the symplasts was determined from serially sectioned tissue, by drawing nuclei with a camera‐lucida, and by counting nuclei. After extensive examination of tubules, the number of spermatids found in the suspected five largest clones observed was determined to be 650, 607, 338, 240, and 177. The segment and subsegment length and the density of spermatids per given tubule length were determined from previously published data. The numbers of spermatids accommodated in the smallest segment and subsegment were 128 and 30, respectively. Our observations indicate that synchronous development of germ cells along the length of the tubule is controlled by intercellular bridges since the number of conjoined cells required to fill a segment or subsegment is more than the number of cells in the smallest arbitrarily identified units of synchrony cataloged to date.
Localization of boar sperm proacrosin during spermatogenesis and during sperm maturation in the epididymis
Authors: Bozzola J. J. , Polakoski K. , Haas N. , Russell L. D. , Campbell P. , Peterson R. N.
Published: February 2005

The localization of proacrosin was determined by using colloidal gold labeling and electron microscopy of boar germ cells during spermiogenesis to post‐ejaculation. Proacrosin was first localized in round spermatids during the Golgi phase of spermiogenesis; it was associated with the electron‐dense granule, or acrosomal granule that was conspicuous within the acrosome. It remained within the acrosomal granule during the cap and acrosome phases of spermiogenesis. At these stages, there was no apparent association of the proacrosin molecule with the acrosomal membranes. During the maturation phase of spermiogenesis, proacrosin was seen to become dispersed into all regions of the acrosome except the equatorial segment. When sperm from different segments of the epididymis and ejaculated sperm were examined, localization was observed throughout the acrosome except for the equatorial segment. Here proacrosin appeared to be localized on both the inner and outer acrosomal membranes as well as with the acrosomal matrix, although further studies are required to verify the membrane localization. No labeling was seen on the plasma membrane. These data suggest that the synthesis and movement of proacrosin to sites in the acrosome are controlled by an as yet unknown process. The absence of proacrosin on the plasma membrane of mature ejaculated sperm makes it unlikely that this enzyme plays a role in sperm‐zona adhesion prior to capacitation.
Structural characteristics of immature rat sertoli cells in vivo and in vitro
Authors: Kelly Cheri W. , Janecki Andrzej , Steinberger Anna , Russell Lonnie D.
Published: February 2005

The structural properties of pelleted prepubertal Sertoli cells (pre‐culture pelleted cells) from 19‐day‐old rats and of similar cells cultured for 7 days were compared with Sertoli cells from the intact animal (testis tissue from 19‐and 26‐day‐old rats, the in vivo groups). Sertoli cells from freshly isolated pellets and those cultured for 7 days were similar in cell and nuclear volumes to their in vivo counterparts. Cell volumes, organelle volumes, and organelle volume densities of newly isolated Sertoli cells were similar to those of sectioned cells taken from the 19‐day‐old in vivo group, indicating that the procedure for isolation does not grossly alter Sertoli cells. Mean height of cells cultured for 7 days was significantly lower than that of cells from intact animals at 19 and 26 days of age. In vivo, Sertoli cells of 26‐day‐old animals displayed increased organelle volumes and organelle surface areas compared with those from 19‐day‐old animals; volume densities and surface densities remained relatively constant, indicating that in vivo, organelle growth is in proportion to growth of the cell. Most organelle volume and surface densities were not significantly different when 19‐day‐old in vivo cells and pre‐culture pelleted cells were compared. Many organelle volume and surface density values were significantly less in cells grown in culture for 7 days as compared to freshly isolated pelleted cells. After 7 days of culture, most Sertoli cell organelles were significantly less in both volume density and surface density, as compared to the in vivo cell groups (19 or 26 day). This indicates that in vitro the organelles do not develop in proportion to the growth of the cell. After 7 days in culture, the absolute volumes and surface areas of the organelles remained generally unchanged as compared to cells from 19‐day‐old animals. The data show that Sertoli cells grow in volume in vitro like their in vivo counterparts; however, their subcellular features, although well maintained, do not develop in proportion to the cell. This suggests that short‐term cultures are a more ideal system in which to study biochemical responses. Also, cultured prepubertal Sertoli cells are most appropriately used to study prepubertal Sertoli cell function. This is the first study to quantify developmental changes in Sertoli cell structure in vivo as well as to compare them with cellular changes occurring in vitro.
Chorioallantoic placenta formation in the rat: I. Luminal epithelial cell death and extracellular matrix modifications in the mesometrial region of implantation chambers
Authors: Welsh Alerick O. , Enders Allen C.
Published: February 2005

On days 7 and 8 of pregnancy, mesometrial regions of rat gestation sites were examined by light microscopy and transmission electron microscopy to determine what changes occur before the chorioallantoic placenta forms in that region. By day 7, gestation sites contained a uterine lumen mesometrially and an antimesometrial extension of the uterine lumen, the implantation chamber. The implantation chamber consisted of a mesometrial chamber between the uterine lumen and the conceptus, an antimesometrial chamber that contained the conceptus, and a decidual crypt antimesometrial to the conceptus. Stromal cells that formed the walls of the implantation chamber were closely packed decidual cells, while those that surrounded the uterine lumen were loosely arranged. Late on day 7, a portion of the epithelium lining the mesometrial chamber was degenerating, but this area of initial degeneration was never adjacent to the antimesometrial chamber. By early day 8, most of the epithelial cells lining the mesometrial chamber were degenerating and were being sloughed into the chamber lumen. Although degeneration of these epithelial cells morphologically resembled necrosis, it was precisely controlled, since adjacent epithelial cells lining the uterine lumen remained healthy. The space that separated the denuded luminal surface of the mesometrial chamber from underlying decidual cells became wider and was occupied by an extracellular matrix rich in cross‐banded collagen fibrils. Decidual cell processes, that earlier had penetrated the basal lamina beneath healthy epithelial cells, protruded into this matrix and penetrated the basal lamina at the luminal surface. By late day 8, large areas of denuded chamber wall were covered with decidual cell processes, little remained of the basal lamina, and cross‐banded collagen fibrils were scarce in the area occupied by decidual cell processes. During the times studied, uterine tissues that formed the walls of the mesometrial chamber were not in direct contact with the conceptus. This study indicates that trophoblast does not play a direct role in epithelial degeneration, basal lamina penetration, or extracellular matrix modifications in the mesometrial region of implantation chambers where part of the chorioallantoic placenta forms, although trophoblast may be required to trigger or modulate some of the changes.
Arrangement and innervation of the iliocostalis and longissimus muscles of the brown caiman (Caiman crocodilus fuscus: Alligatoridae, crocodilia)
Authors: Murakami Gen , Akita Keiichi , Sato Tatsuo
Published: February 2005

The axial musculature of the brown caiman was investigated in detail with particular attention to the nerve supply, using a binocular stereomicroscope. Due to the prominent development of the longissimus (Lo) and the iliocostalis (IC) muscles of the caiman, the pattern of distribution of the spinal nerves in the body wall was unique; there also was less differentiation of the external intercostalis. There were four primary divisions of the spinal nerves in the thoracic region of the caiman, from ventral to dorsal: the intercostal nerve, the IC nerve, the Lo nerve, and the dorsal main trunk. Thus, the classic concept of the organization of the spinal nerves may not be suitable for the caiman. These findings suggest that evolutionary changes in the dorsolateral axial musculature have brought about the rearrangement of the organization of the spinal nerves. In addition, each clearly segmented myotome of the Lo and IC was innervated by more than two segments of the spinal nerves (pluriseg‐mental innervation). The manner of formation of the myotome and its innervation is discussed from the viewpoint of comparative and developmental anatomy.
Initiation and pattern of angiogenesis in wound healing in the rat
Authors: Phillips Gregg D. , Whitehead Russell A. , Knighton David R.
Published: February 2005

The object of this study was to examine the initiation and pattern of capillary growth associated with wound healing. Collagen sponges were implanted subcutaneously in the hind limbs of adult male rats to stimulate the formation of granulation tissue. Blood vessels of the hind limbs of euthanized rats were perfused with Mercox (an acrylic monomer) via the abdominal aorta at selected periods of time following sponge implantation. When the perfusate was completely cured, the sponge and parajacent tissues were excised and subsequently macerated by alternating immersion in 40% KOH and distilled water. Cast replicas of the vascular lumina were coated with gold and imaged by scanning electron microscopy. At 6 hr, punctate depressions at the periphery of the replicas of vein and venule lumina were noted. The depressions represented sites of leukocyte margination. By 24 hr, the depressions increased numerically, indicating a great increase in the sites of leukocyte margination. The number of these depressions decreased by 48 hr. Concomitantly, the depressions representing endothelial cell nuclei became more pronounced, indicating nuclear hypertrophy of these cells. In addition, capillary bud formation was initiated. At 72 hr, capillary buds were quite apparent and arose solely from venules. Between 7 and 14 days, replicas of capillary lumina were longer and formed an elaborate network, presumably by end‐to‐end, side‐to‐side, and end‐to‐side anastomoses. The network was formed circumferential to the sponge and then capillary sprouts entered the sponge's interstitial spaces.
Hypophyseal angioarchitecture of common tree shrew (Tupaia glis) revealed by scanning electron microscopy study of vascular corrosion casts
Authors: Sudwan Paiwan , Chunhabundit Panjit , Bamroongwong Sirinush , Rattanachaikunsopon Pongsak , Somana Reon
Published: February 2005

The vascular corrosion cast technique in conjunction with scanning electron microscopy (SEM) was used for the study of pituitary microvascularization in the common tree shrew (Tupaia glis). The pituitary vascular casts were obtained by infusion of low viscosity methyl methacrylate plastic (Batson's no. 17) mixture. It was found that the blood supplies to the pituitary complex were from branches of the circle of Willis and could be divided into two groups. The first group consisted of two to four superior hypophyseal arteries (SHAs) branching off from the internal carotid artery supplying each half of the median eminence (ME), infundibular stalk (IS), and pars distalis (PD). The SHAs supplying the ME branched into internal and external capillary plexi. The internal plexus had a larger capillary size (approximately 15 μm in diameter), was deeper in position, and had denser and more complex capillary loops than those in the external plexus. The capillaries of the external plexus were approximately 10 μm in diameter. The two plexi drained into 15–20 hypophyseal portal veins (HPVs) which were located mainly along the ventral and ventrolateral surfaces of the IS before breaking up into large capillaries (approximately 18 μm in diameter) with an anteroposterior arrangement within the PD. The second group consisted of one inferior hypophyseal artery (IHA) on each side branching off from the internal carotid artery. These arteries gave off branches to pierce the dorsolateral and ventrolateral aspects of infundibular process (IP) before branching off to form a capillary network. They also gave rise to radiating capillaries to supply the pars intermedia (PI) surrounding the cortical area of the IP. The hypophyseal cleft separating the PI from the PD was clearly seen with very few blood vessels. The capillaries in both PD and IP joined to form confluent hypophyseal veins draining the blood into the cavernous sinus.
Sensory innervation of the canine esophagus, stomach, and duodenum
Authors: Khurana Ramesh K. , Petras J. M.
Published: February 2005

The sensory innervation of the postpharyngeal foregut was investigated by injecting the enzyme horseradish peroxidase (HRP) into the walls of the esophagus, stomach, or duodenum. The transported HRP was identified histochemically, labeled neurons in the spinal and vagal ganglia were counted, and the results were plotted using an SAS statistical program. The spinal sensory fields of each viscus were defined using three determinations: craniocaudal extent, principal innervation field, and peak innervation field. The data revealed that innervation fields are craniocaudally extensive, the sensory field of each viscus overlaps significantly with its neighbor, yet each viscus can be characterized by a field of peak innervation density.

Craniocaudal innervation of the esophagus spans as many as 22–23 paired spinal ganglia (C1‐L2). There are two peak innervation fields for the cervical (C2‐C6 and T2‐T4) and for the thoracic (T2‐T4 and T8‐T12) sectors of the esophagus. The sensory innervation of the stomach extends craniocaudally over as many as 25 paired spinal ganglia (C2‐L5). The peak innervation field of the stomach spans a large area comprising the cranial, middle, and the immediately adjoining caudal thoracic ganglia (T2‐T10). The duodenum is innervated craniocaudally by as many as 15 paired thoracolumbar ganglia (T2‐L3). Peak innervation originates in the middle and caudal thoracic ganglia and cranial lumbar (T6‐L1) ganglia. There is a recognizable viscerotopic organization in the sensory innervation of the postpharyngeal foregut; successively more caudal sectors of this region of the alimentary canal are supplied with sensory fibers from successively more caudal spinal dorsal root ganglia.

Vagal afferent innervation of the esophagus, stomach, and duodenum is bilateral and originates predominantly, but not exclusively, from vast numbers of neurons in the nodose (distal) ganglia. The esophagus is innervated bilaterally and more abundantly by jugular (proximal) ganglia neurons than is either the stomach or duodenum.

The physiological significance of the findings are discussed in relation to the phenomena of visceral pain and referred pain.
Early stages of trophoblastic invasion of the maternal vascular system during implantation in the macaque and baboon
Authors: Enders Allen C. , King Barry F.
Published: February 2005

Trophoblastic invasion and remodeling of the uteroplacental (spiral) arteries in primates are well‐documented, but virtually nothing is known of the early stages of these phenomena. Therefore, we examined invasion of the maternal vasculature in macaques and baboons at, and immediately following, implantation. Following penetration of the uterine epithelium (day 9), trophoblast spreads along the residual epithelial basal lamina. By day 10, cytoplasmic processes penetrate the epithelial and endothelial basal laminase, and syncytial trophoblast insinuates itself between maternal endothelial cells. As lacunae develop, both syncytial and cytotrophoblast are exposed to maternal blood. Endovascular cytotrophoblast was first observed in subepithelial dilated capillaries and venules. These vessels are lined by increasingly hypertrophied endothelial cells. The spiral arterioles are unmodified at this time. Particularly interesting was the observation that there is rapid extensive endovascular trophoblast invasion of the spiral arterioles immediately beneath the implantation site. By day 14–16 nearly all of the small arterioles directly beneath the site are completely occluded. There is no invasion of the veins in this region. Somewhat later, the deeper arterioles in the principal zone are invaded. Rather than a continuous stream of cells invading the deeper arterioles, these endovascular cells occur in clusters ranging from a few cells to groups of cells that completely plug the lumen. Our results indicate that trophoblastic invasion of maternal vessels occurs very early; and, at least initially, trophoblast can migrate between and along endothelial cells without causing their lysis. The endovascular cells eventually interrupt the endothelial lining of the arterioles and penetrate the walls of the vessels. The occlusion of arterioles underneath the site suggests that circulation through the lacunae at this stage is indirect. Corresponding stages of human development were examined, and no invasion of arterioles could be observed prior to formation of an extensive cytotrophoblastic shell.