bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chorioallantoic placenta formation in the rat: II. Angiogenesis and maternal blood circulation in the mesometrial region of the implantation chamber prior to placenta formation
Authors: Welsh Alerick O. , Enders Allen C. 
Published: February 2005

AbstractRat gestation sites were examined on days 7 through 9 of pregnancy by light microscopy and transmission and scanning electron microscopy to determine the extent of vascular modifications in the vicinity of the mesometrial part of the implantation chamber (mesometrial chamber). At a later time, the mesometrial chamber is, in conjunction with the uterine lumen, the site of chorioallntoic placenta formation. On day 7, in the vicinity of the mesometrial chamber, vessels derived from a subepithelial capillary plexus and venules draining the plexus were dilating. By early day 8, this network of thin‐walled dilated vessels (sinusoids) was further enlarged and consisted primarily of hypertrophied endothelial cells with indistinct basal laminas. Sinusoids were frequently close to the mesometrial chamber's luminal surface which was devoid of epithelial cells but was lined by decidual cell processes and extracellular matrix. By late day 8, cytoplasmic projections of endothelial cells extended between healthy‐appearing decidual cells and out onto the mesometrial chamber's luminal surface, and endothelial cells were sometimes found on the luminal surface indicating that endothelial cells were migrating. The presence of maternal blood cells in the mesometrial chamber lumen suggested that there was continuity between the chamber and blood‐vessel lumens. On day 9, the mesometrial chamber was completely lined with hypertrophied endothelial cells, and sinusoid lumens were clearly continuous with the lumen of the mesometrial chamber. Mesometrial sinusoids and possibly the mesometrial chamber lumen were continuous with vessels in the vicinity of the uterine lumen that were fed by mesometrial arterial vessels. Clearing of the mesometrial chamber lumen during perfusion fixation via the maternal vasculature indicated the patency of this luminal space and its confluence with mesometrial arterial vessels and sinusoids. The conceptus occupied an an‐timesometrial position in the implantation chamber on days 7 through 9, and it was not in direct contact with uterine tissues in the vicinity of the mesometrial chamber. These observations suggest that angiogenesis, not trophoblast invasion or decidual cell death, plays a major role in the opening of maternal vessels into the mesometrial chamber lumen before the formation of the chorioallantoic placenta.
Trophoblast‐Uterine interactions during equine chorionic girdle cell maturation, migration, and transformation
Authors: Enders Allen C. , Liu I. K. M. 
Published: February 2005

AbstractThe structure of the equine chorionic girdle between days 28 and 42 of gestation was examined. Of particular interest were differentiation of trophoblastic cells within the girdle, adhesion between girdle and endometrium, invasion and displacement of the uterine epithelium, and the nature of the endometrium when girdle cells migrate into it to form endometrial cup cells. The chorionic girdle, identified initially as a band of tall columnar cells, becomes a stratified columnar epithelium indented by clefts and pits. Adhesion to and penetration through the endometrial luminal epithelium are rapid and occur initially in very limited areas. Stromal invasion occurs as strands of contiguous trophoblast cells invade through the basal lamina. Only girdle cells that are adjacent to the basal lamina or have entered the endometrial stroma undergo hypertrophy and differentiate into cup cells. At the initiation of trophoblastic invasion, the luminal epithelium contains numerous, large, intra‐epithelial, granular lymphocytes; small lymphocytes then accumulate in the stroma, but by day 42 lymphocytes are largely confined to the periphery of the cup. Although adhesion of trophoblast to the endometrial surface is initiated by small groups of girdle cells on restricted areas of the endometrial folds, the area is then increased by new areas of adhesion and by expansion of the initial invasion. Areas of girdle cells that do not attach undergo necrosis, as do superficial portions of areas of invasion. Consequently the girdle cells that form cups may be a minority of the original population. It is suggested that the differentiation of girdle cells is closely programmed and that cells that do not reach the stroma become necrotic at the same time that endometrial cup cells are differentiating.
Growth of mouse ectoplacental cone cells in subcutaneous tissues. Development of placental‐like cells
Authors: Bevilacqua Estela Maris A. F. , Faria Miriam R. , Abrahamsohn Paulo A. 
Published: February 2005

AbstractEctoplacental cones of mouse embryos collected on day 8 of pregnancy were grafted into the dorsal subcutaneous tissue of host mice. The grafts were collected between days 3 and 8 after transfer and processed for light and electron microscope morphological analysis as well as for cytochemistry of nonspecific alkaline phosphatase. Fragments of normal mouse placentas collected between days 12 and 18 of pregnancy were processed similarly. About 37% of the grafts were nonhemorrhagic nodules formed by different kinds of trophoblastic cells. These cells had many morphological and cytochemical features of cells present in normal mouse placentas. Nonphagocytic giant cells, glycogen cells, as well as cells with a well‐developed granular endoplasmic reticulum were similar to cells found in the placenta and were always present in the grafts. Cells showing features intermediate between the above‐mentioned cells and those whose cytoplasm was poor in organelles also were found in the grafts. The latter resembled cells of layer 1 of the labyrinth of the placenta. These results suggest that trophoblastic cells of the ectoplacental cones had differentiated into placental cells following their transfer to the subcutaneous tissue.
Hyaluronic acid influences the migration of myoblasts within the avian embryonic wing bud
Authors: Krenn Veit , Brand‐Saberi Beate , Wachtler Franz 
Published: February 2005

AbstractMyoblasts migrate in a proximodistal direction within the avian embryonic wing bud during normal limb development. Since the presence and distribution of hyaluronic acid within the wing bud coincide with the time and with the direction of the migration of myoblasts, we microinjected hyaluronic acid into chicken wing buds that had received grafts containing quail myoblasts. It was found that injected hyaluronic acid has a strong positive effect on the migration of myoblasts: it causes a migration of myoblasts in donor‐host combinations in which this is normally not the case, and it can cause migration in a proximal direction, a phenomenon not observed during normal development. From this it may be concluded that hyaluronic acid can influence myoblast migration in vivo. A similar effect could be observed after the microinjection of dextran sulfate, a synthetic compound having similar physicochemical properties. Hyaluronic acid, therefore, may play an important role in the control of the migration of myogenic cells in vivo by its physicochemical properties.
Growth and development of the human infant breast
Authors: Anbazhagan R. , Bartek J. , Monaghan P. , Gusterson B. A. 
Published: February 2005

AbstractSeventy‐two samples of infant breasts, aged from newborn to 2 years, were collected at necropsy. Whole‐mount preparations and histological sections were made. A system of classification was devised to study the extent of the structural development of the ductal system (morphological types I, II, and III) and the functional differentiation of the lining epithelium (functional stages I to V). There was no correlation between the age of the infant and the type of development of the ductal system. In contrast, the epithelial differentiation followed a chronological pattern, starting with secretory changes and apparently going through a period characterized by apocrine metaplasia before post‐secretory involution. These epithelial changes were not associated with the morphological type of the ductal system. There were no distinguishing features between the breasts from the two sexes.Immunoperoxidase staining for actin and kappa‐casein was carried out to study the myoepithelial cells and secretory cells, respectively. Myoepithelial cells were present at all stages and prominent staining for casein was observed up to 2 months of age. Embryonic‐type adipose tissue was seen in 7 cases, in one of which it was associated closely with the developing ductal system. Extramedullary hematopoiesis was observed in the periductal connective tissue until 4 months of age.This paper describes the most extensive anatomical and histological study of the human infant breast to date and lays the foundation for a detailed study of the epithelial and stromal changes that take place during human breast development.
Numbers of myosatellite cells in white axial muscle of growing fish: Cyprinus carpio L. (teleostei)
Authors: Koumans J. T. M. , Akster H. A. , Booms G. H. R. , Lemmens C. J. J. , Osse J. W. M. 
Published: February 2005

AbstractBy means of transmission electron microscopy (TEM), the percentage of myosatellite cells was shown to decrease from about 6% in carp of 5 cm standard length (SL) to less than 1% in carp larger than 18 cm SL. The ratio between muscle nuclei and non muscle nuclei remained constant. These TEM data, combined with data on the amount of DNA per gram of muscle tissue and per nucleus, were used to calculate the numbers of myosatellite cells per gram of tissue (TEM‐DNA method). Total numbers of myosatellite cells could be calculated from the TEM‐DNA data and the calculated amounts of muscle tissue per fish. After a slight initial increase, the total number of myosatellite cells in the white axial muscle of a carp appears to be rather constant during the growth phase of the fish. But the myosatellite cells become more and more diluted over an increasing number of myonuclei with age. In addition, the reliability of two new light microscopic methods for the determination of numbers of myosatellite cells was examined. The percentages of myosatellite cells were determined by counting the numbers of total nuclei and of heterochromatic nuclei situated inside the muscle fibers' basal laminae which were stained using an antibody against laminin. These percentages were not significantly different from those determined with TEM. The yield of myosatellite cells per gram of muscle tissue, isolated with a previously developed dissociation method, showed a direct relation to the number of myosatellite cells calculated to be present in the tissue (TEM‐DNA method), but at a 1% level. Both methods are alternative ways to determine numbers of myosatellite cells when it is impossible or difficult to use TEM (e.g., large sample sizes, combination with immunohistochemical methods).
Myofiber orientation in the weanling mouse heart
Authors: McLean Miriam , Prothero John 
Published: February 2005

AbstractThis study provides a quantitative description at the cellular level of myofiber orientation throughout the ventricles of the mouse heart. We employed computer‐based methods of three‐dimensional reconstruction from 3 μm plastic‐embedded serial sections. Registration marks were introduced by drilling minute holes into each plastic block. Subfields of selected sections were photographed at 20 x magnification, using a computer‐controlled microscope. The 35‐mm film frames were projected onto a digitizer tablet and the epi‐ and endocardial boundaries were digitized manually. The “heads” and “tails” of linear segments of a representative myofiber sample present in each projected image were digitized in point mode. The many x‐, y‐, z‐coordinate tables generated by digitization were reassembled automatically, giving a numerical description of the myofiber pattern. This pattern was studied interactively on a high‐performance graphics workstation. We find that the heart wall is, to a first approximation, a “sandwich,” in which the myofibers in the middle layer run mainly circumferentially, whereas those in the inner and outer layers run parallel or oblique to the apical‐basal axis, a variant of the classical model of the myofiber pattern. We observed a “sleeve” in the interventricular septum, formed by longitudinal and oblique myofibers, a feature which apparently has not been described previously. Myofibers not running parallel to the transverse or longitudinal planes were not resolved in this study. We conclude that three‐dimensional reconstruction of the cardiac myofiber pattern at the light‐microscopic level, while laborious, is technically feasible and scientifically worthwhile.
The role of growth factors in the embryogenesis and differentiation of the eye
Authors: Tripathi Brenda J. , Tripathi Ramesh C. , Livingston Amit M. , Borisuth NavaneetS. C. 
Published: February 2005

AbstractThe vertebrate eye is composed of a variety of tissues that, embryonically, have their derivation from surface ectoderm, neural ectoderm, neural crest, and mesodermal mesenchyme. During development, these different types of cells are subjected to complex processes of induction and suppressive interactions that bring about their final differentiation and arrangement in the fully formed eye. With the changing concept of ocular development, we present a new perspective on the control of morphogenesis at the cellular and molecular levels by growth factors that include fibroblast growth factors, epidermal growth factor, nerve growth factor, plateletderived growth factor, transforming growth factors, mesodermal growth factors, transferrin, tumor necrosis factor, neuronotrophic factors, angiogenic factors, and antiangiogenic factors. Growth factors, especially transforming growth factor‐β, have a crucial role in directing the migration and developmental patterns of the cranial neural‐crest cells that contribute extensively to the structures of the eye. Some growth factors also exert an effect on the developing ocular tissues by influencing the synthesis and degradation of the extracellular matrix. The mRNAs for the growth factors that are involved in the earliest aspects of the growth and differentiation of the fertilized egg are supplied from maternal sources until embryonic tissues are able to synthesize them. Subsequently, the developing eye tissues are exposed to both endogenous and exogenous growth factors that are derived from nonocular tissues as well as from embryonic fluids and the systemic circulation. The early interaction between the surface head ectoderm and the underlying chordamesoderm confers a lens‐forming bias on the ectoderm; later, the optic vesicle elicits the final phase of determination and enhances differentiation by the lens. After the blood–ocular barrier is established, the internal milieu of the eye is controlled by the interactions among the intraocular tissues; only those growth factors that selectively cross the barrier or that are synthesized by the ocular tissues can influence further development and differentiation of the cells. An understanding of the tissue interactions that are regulated by growth factors could clarify the precise mechanism of normal and abnormal ocular development.
Monkey photoreceptor calycal processes and interphotoreceptor matrix as observed by scanning electron microscopy
Authors: Rana M. W. , Taraszka S. R. 
Published: February 2005

AbstractPhotoreceptors and the interphotoreceptor matrix of monkey retina were observed by scanning electron microscopy. Cone photoreceptors are easily distinguished from rod photoreceptors by their wide conical inner segments. The calycal processes of 50 rods and 50 cones were counted and measured. The calycal processes of cones were distinct, short, and uniform in diameter (0.1 μm). They were arranged equidistantly and, in most cases, were not continuous with longitudinal inner segment ridges, as previously suggested. In contrast to cones, rod calycal processes were fewer in number, were about one‐fourth the number of the cones, were of variable length (0.7 μm to 3.0 μm), and tapered to a fine point at their distal ends. The interphotoreceptor matrix appeared spongelike, made up of anastomosing plates and strands filling the interphotoreceptor space. Other than an increased amount of matrix around cones, no structural difference between rod‐ and cone‐associated interphotoreceptor matrix was observed.
Human spinal arachnoid septa, trabeculae, and “rogue strands”
Authors: Parkinson Dwight 
Published: February 2005

AbstractThis study was undertaken because of confusion arising from a diversity of names, descriptions, and drawings of the human spinal subarachnoid septa and trabeculae in the standard texts and dictionaries. Sixty‐two complete human cords were examined under the dissecting scope. The finely “woven” adult arachnoid membrane was two‐layered, and there were essentially no connecting septa or trabeculae between the cord and the arachnoid membrane anteriorly. Posteriorly, in the upper cervical region there is a scanty series of connecting fibers and fenestrated sheets 1 or 2 mm on either side of the midline; these become progressively more extensive in the lower cervical region, remain extensive to the lumbar enlargement, beyond which they progressively dwindle to end abruptly at the filum terminale origin. Throughout the cauda equina, strands are haphazardly arranged connecting the roots and supporting blood vessels. These occasionally become tangentially adherent to the arachnoid membrane. Throughout the length there are many unexplained, redundant, nonbranching, beaded, thicker “rogue strands”. All of the above are of a different character from the right‐angle fiber arrangement of the denticulate ligament, the two leaves of which are often separated to form segmental longitudinal tunnels. The nerve rootlets (fila radicularia) for each dermatome are joined by strands and webs to each other. There was no evidence of change in number or type of connection with age.
S‐Antigen and glial fibrillary acidic protein immunoreactivity in the in situ pineal gland of hamster and gerbil and in pineal grafts: Developmental expression of pinealocyte and glial markers
Authors: Li Kang , Welsh Marcia G. 
Published: February 2005

AbstractPostnatal development of S‐Ag and GFAP immunoreactivity in the in situ pineal glands of golden hamsters and gerbils was examined using the avidin‐biotin‐peroxidase immunohistochemical technique. S‐Ag was present in the gerbil pineal gland on the first postnatal day (P1), whereas it did not appear in the hamster pineal until P6. GFAP‐immunoreactive astrocytes were first observed in the hamster pineal gland on P7 and in the gerbil pineal gland on P10. The number of S‐Ag‐immunoreactive pinealocytes and GFAP‐immunoreactive astrocytes in the pineal glands of hamsters and gerbils increased with increasing age from P7 to 3 weeks. By 4 weeks, strong S‐Ag and GFAP immunoreactivity was observed in both hamster and gerbil pineal glands. GFAP‐immunoreactive stellate astrocytes were distributed evenly throughout the gerbil superficial pineal gland, but they were more often located in the peripheral region of the hamster superficial pineal. For the pineal grafts, pineal glands from neonatal (3–5 day old) hamsters were transplanted into the third cerebral ventricle (infundibular recess or posterior third ventricle) or beneath the renal capsule of adult male hamsters. S‐Ag immunoreactivity appeared in the pineal grafts within 1 week following transplantation. By 4 weeks the pineal grafts showed strong S‐Ag immunoreactivity which was maintained until at least 12 weeks after transplantation. The time course of glial cell maturation in the cerebroventricular pineal grafts is generally parallel to the hamster pineal gland in situ before 4 weeks. By 12 weeks, however, more astrocytes differentiated and developed GFAP‐immunoreactivity in the pineal grafts than in the in situ pineals. These studies have described the postnatal development of S‐Ag and GFAP immunoreactivity in in situ pineal glands and in neonatal pineal grafts.
Reorganization of the ependyma during axolotl spinal cord regeneration: Changes in intermediate filament and fibronectin expression
Authors: O'Hara Christina M. , Egar Margaret W. , Chernoff Ellen A. G. 
Published: February 2005

AbstractChanges in intermediate filament content and extracellular matrix material showed that the injury response of ependymal cells in lesioned axolotl spinal cord involves an epithelial‐to‐mesenchymal transformation, and that fibrous astrocytes are excluded from the remodeling lesion site. Antibody localization was used to visualize cytokeratin‐, vimentin‐, and glial fibrillary acidic protein‐ (GFAP‐) containing intermediate filaments, as well as the adhesive glyco‐protein fibronectin. In normal axolotl spinal cord cytokeratins were found near the apical surface of the ependymal cells. Transmission electron microscopic examination suggested that these cytokeratins were in tonofilaments. Cytokeratin expression was lost and vimentin production was initiated in ependymal cells 2–3 weeks following spinal cord injury. There was a period of approximately 1–2 weeks when cytokeratins and vimentin were co‐expressed in vivo. This co‐expression was maintained in vitro by culture on a fibronectin‐coated substratum. As the central canal reformed, vimentin expression was lost. Ependymal cells lacked GFAP intermediate filaments, but GFAP was present in fibrous astrocytes of the neuropil and white matter. Following injury, GFAP localization showed that fibrous astrocytes disappeared from the remodeling lesion site and reappeared only after the ependymal epithelium reformed and newly myelinated axons were found. Fibronectin expression closely followed the expression of vimentin during mesenchymal ependymal cell outgrowth. These results suggest that the ependymal cell outgrowth requires changes in cell shape followed by changes in production of extracellular matrix.
Onset of expression and regional deposition of alpha‐smooth and sarcomeric actin during avian heart development
Authors: Sugi Yukiko , Lough John 
Published: February 2005

AbstractThe sequential appearance of mRNAs for smooth, cardiac, and skeletal alpha‐actin has been described during development of the chicken heart (Ruzicka, D.L., and R.J. Schwartz 1988 J. Cell Biol., 107:2575–2586). To assess whether this reflects the deposition of corresponding isoproteins, we have immunocytochemically localized smooth and sarcomeric (cardiac and skeletal) alpha‐actin in Hamburger‐Hamilton (H‐H) stage 7–18 embryos using monoclonal antibodies. Within the developing embryo at stage 9‐, smooth muscle alpha‐actin was exclusively detected in the developing heart, upon fusion of the endocardial tubes; sarcomeric alpha‐actin was observed later (stage 9). By the onset of contraction at stage 10 +, intense immunostaining of both smooth and sarcomeric isoproteins was observed in the ventricle; at this time smooth muscle alpha‐actin was also detected in splanchnic mesoderm of the pre‐vitelline area, in a cellular layer adjacent to the only embryonic cells that exhibited factor VIII (von Willebrand factor) antigens. Double immunostaining of the myocardium at stage 11, at which time striations were first detected, revealed the co‐existence of smooth and sarcomeric actin in developing sarcomeres. Intense expression of sarcomeric actin continued in the heart after stage 11, whereas smooth muscle alpha‐actin was down‐regulated in the ventricle and became regionalized to the inflow and outflow tracts. As expected, smooth muscle alpha‐actin was detected around intra‐ and extra‐embryonic vascular structures at later developmental stages, while sarcomeric actin was observed in somites.