bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of intravenously injected cationized ferritin within developing glomerular basement membranes of newborn rat kidneys
Authors: Abrahamson Dale R. , Perry Elizabeth W.
Published: February 2005

To label heparan sulfate proteoglycans and other strong anions within glomerular basement membranes (GBM) during assembly, cationized ferritin (CF), with a narrow isoelectric range of 7.7 to 8.2, was intravenously injected into newborn rats. Kidneys were then fixed and processed for electron microscopy at intervals ranging from 1 to 72 h after CF injection. One hour after injection, CF bound extensively to the lamina rara interna and externa of developing GBM and mesangial matrix and to tubular basement membranes (TBM). In double basement membranes of early stage glomeruli, large amounts of CF were also seen in central areas between the endothelial and epithelial basement membranes. In maturing‐stage glomeruli, CF bound throughout interior regions of GBM outpockets projecting into the epithelial side of capillary walls as well as to the laminae rarae. Because in adult rats CF binds only to the laminae rarae, the abundant anionic sites seen here in newborns between double basement membranes and within GBM outpocket interiors may be subsequently neutralized or removed during the GBM assembly process. In addition to basement membranes, CF was also located intracellularly within endocytic vesicles and lysosomes of glomerular endothelial, mesangial, and epithelial cells 1 h postinjection. CF was also present in similar structures within the tubular epithelium. In contrast to these findings, CF was gradually lost from developing GBM 5, 15, and 24 h after injection and was essentially cleared from all GBM, mesangial matrices, and TBM after 48 h. Large CF aggregates were progressively accumulated within mesangial lysosomes, however. The transient binding of CF to GBM anionic sites seen here was most likely due to its endocytic removal by developing glomerular endothelial, mesangial, and epithelial cells. Anions in the circulation probably also competed effectively with the GBM and TBM for bound CF.
Rotation of the junction of the outflow tract and great arteries in the embryonic human heart
Authors: Lomonico M. Paul , Moore G. William , Hutchins Grover M.
Published: February 2005

The factors which give rise to the normal relationship between the great arteries and their respective ventricles are unknown. The developmental anatomy of this region was studied by using frontal, sagittal, or transverse serial histologic sections of 17 normal human embryos of Carnegie stages 15–19 from the Carnegie Embryological Collection. Distances and angles between major anatomic landmarks were determined by using computer reconstructions of the serially sectioned embryos, three‐dimensional analytic geometry, and Euclidean distance formulas. The findings show that between stages 15 and 19 there is a marked rotation of the axis of the semilunar valves: frontal 121° counterclockwise, sagittal 196° counterclockwise, and transverse 240° clockwise. Simultaneously the great arteries lengthen at a faster rate than the rest of the heart; and there is also an increase in the caliber and wall thickness of the great arteries. These results suggest that the changing rate of growth between the great arteries and the heart is necessary to align the great arteries, the semilunar valves, and the muscular outflow tract septum appropriately with respect to the interventricular septum. Reductions in the rate of growth of the great arteries relative to the heart could, by causing changes in the rotation of great arteries and outflow tract septum, have a role in the pathogenesis of cardiovascular malformations such as tetralogy of Fallot and transposition of the great arteries.
Further ultrastructural observations on the sperm head of the plains mouse, Pseudomys australis (Rodentia: Muridae)
Authors: Flaherty Sean P.
Published: February 2005

Ultrastructural and histochemical techniques have been utilized to study selected aspects of the fine structure of the three‐hooked sperm head of the plains mouse, Pseudomys australis. The peripheral layer of the two ventral hooks was found to consist of a continuation of the postacrosomal dense lamina. Parallel ridges connected the dense lamina and plasma membrane in the postacrosomal region and ventral hooks. Both these regions stained intensely with silver nitrate. The distribution of action filaments in the hooks was investigated using NBD‐phallacidin. Fluorescence was more intense in the apical regions of the ventral hooks, and two bands of fluorescence extended caudally from their base. It was also shown that the equatorial segment of the acrosome extended onto the dorsal hook. The structural features of the three hooks are discussed in relation to their possible functional significance.
Dorsal cerebral collaterals of stroke‐prone spontaneously hypertensive rats (SHRSP) and Wistar Kyoto rats (WKY)
Authors: Coyle Peter
Published: February 2005

Earlier studies established that stroke‐prone spontaneously hypertensive rats (SHRSP) invariably infarct after middle cerebral artery (MCA) occlusion. Normotensive rats are usually protected from infarction after the occlusion. Objectives of this study were to characterize the anastomosing collaterals that may determine the different outcomes to MCA occlusion in SHRSP and Wistar Kyoto rats (WKY). Young (5–10 week) and old (40–69 week) rats of each sex were anesthetized, then administered papaverine to produce maximal vasodilatation of the cerebrovascular bed. Under control conditions latex was injected into the arterial tree to measure the internal diameter of branches of the anterior cerebral artery (ACA), the MCA, and the ACA‐MCA anastomosing collaterals. Large diameter ACA and MCA rami in old, but not young, SHRSP were significantly smaller in diameter than the respective ACA and MCA branches in old WKY. The number of ACA‐MCA anastomoses was the same for SHRSP and WKY. Mean internal diameter of the ACA‐MCA anastomoses was significantly (p < 0.0001) smaller in SHRSP than WKY in both age groups. There were significant negative correlations between age and (1) the internal diameter of the ACA‐MCA anastomoses in WKY but not SHRSP, and (2) the largest diameter ACA and MCA rami in SHRSP but not WKY. The findings suggest that vascular resistance of fully relaxed collaterals is greater in SHRSP than WKY, thereby compromising the dorsal collateral circulation before large diameter vessel changes occur that accompany the established form of hypertension.
Number of mitral cells and the bulb volume in the aging human olfactory bulb: A quantitative morphological study
Authors: Bhatnagar Kunwar P. , Kennedy Ray C. , Baron Georg , Greenberg Richard A.
Published: February 2005

The present study documents the morphological changes in the aging human olfactory bulb. Eight bulb pairs from white females between the ages of 25 and 102 years were used. The number of mitral cells in layers IV and III was determined for each bulb and corrected for spilt cell error. Counts were made on 10‐μm thick Nissl‐stained sections at 250‐μm intervals. The mean number of mitral cells per olfactory bulb at age 25 was estimated from linear regression to be 50,935; at age 60, 32,718; and at age 95, 14,501. The average loss over the time interval studied was 520 mitral cells per year.

The volume of each bulb layer, except layer IV, was determined. The difference in the volume of each layer within individuals with age and the total volume with age was not significant (P < 0.11). The estimated mean bulb volume was found to be 50.02, 43.35, and 36.68 mm3 at ages 25, 60, and 95 years, respectively. The estimated reduction in bulb volume per year increase of age was 0.19 mm3. The ratio of mitral cells to bulb volume for layer III decreased by 19.4 units for every year increase in age. No significant difference was found between the left and the right bulbs in regard to the number of mitral cells and the bulb volume.

Histologically, the glomerular layer thickness as well as the mitral cell size and concentration per unit area decreased with age. The intrabulbar anterior olfactory nucleus was discontinuous, highly variable in size, and presumably variable even in neuronal numbers.
Anomalous interconnection between flexor and extensor carpi radialis brevis tendons
Authors: Nakahashi Takahiro , Izumi Ryutaro
Published: February 2005

A rare case of a short radiocarpal flexor (M. flexor carpi radialis brevis vel profundus of Wood) was found on the right forearm of a 47‐year‐old Japanese male corpse. The muscle arose from the anterior surface of the radius, ran distally in the deep layer of the flexor region to enter deeply into the carpal tunnel, and then interconnected with the subtendon of the extensor carpi radialis brevis at the gap between the bases of the second and third metacarpal bones. This muscle was supplied by a branch of the anterior interosseous nerve.
Occurrence of cells containing paracrystalloid material in the intestinal lamina propria of the hibernating bat Myotis lucifugus
Authors: Payette R. F. , Gershon T. R. , Gershon M. D. , Nunez E. A.
Published: February 2005

A light and electron microscope study of the small intestine of the little brown bat, Myotis lucifugus, was carried out at several stages in the animal's annual life cycle. An unusual morphological observation was the presence of cells in the lamina propria of the small intestine which were packed with a conspicuous basophilic granular material that appeared crystalline. Moreover, such cells were present only during the hibernation period and were therefore called “hibernation crystalloid” (HC) cells. By light microscopy, the crystal‐like material was not sudanophilic, did not stain for nucleic acids, and did not contain acid phosphatase; it did show reactivity when stained by the periodic acid–Schiff procedure. By electron microscopy, the crystal‐like material was found to be present in smooth, membrane‐enclosed vacuoles along with an amorphous, dense granular substance. The crystal‐line material occasionally formed rigid‐appearing rods that reached lengths of 10 μm. The crystal‐containing cells were contacted by axonal varicosities. It is suggested that these innervated HC cells represent a unique cell type with a gastrointestinal function, yet to be determined, that may be related to hibernation.
Maintenance of adult rat ventral prostate in organ culture
Authors: Martikainen Paula
Published: February 2005

Androgens postpone the involution of prostatic tissue cultured in a chemically defined medium. However, after 1 week quantitative changes are accentuated and qualitative signs of involution appear. Other factors in addition to androgens are obviously needed for the adequate maintenance of the tissue. This study was aimed at the improvement of the culture conditions by adding insulin, corticosterone, epidermal growth factor, prolactin, and transferrin alone or in different combinations with testosterone and each other. A morphometric model developed for prostate culture was used, and maintenance and proliferation of the tissue were further followed by weighing the cultured explants and by measuring the incorporation of (3H) thymidine into DNA.

The androgen dependency was seen in all the studied morphometric parameters at least for 2 weeks–i.e., in volume density and height of epithelium (VVEP and h), reflecting the epithelial maintenance, in volume density and width of interacinar tissue (VVIT and λAP), reflecting stromal tissue, and in volume density and diameter of lumen (VVLU and DLU), reflecting the secretory function. Testosterone (10−7 M) also prevented partially the quantitative involution of the tissue within 2 weeks.

Insulin, acting independently of androgen, was a potent mitogen, which, according to morphometric results, exerted its effect mainly on prostatic epithelium. Stratification of epithelium was frequently seen. Corticosterone had no effect on epithelian proliferation, but it probably stimulated secretion and inhibited the growth of stroma.

By combining these three hormones it was possible to maintain not only the structure but also the amounts of tissue components practically unaltered at least for 2 weeks.

Epidermal growth factor (EGF) and prolactin had only marginal effects, and transferrin had none. It remains to be settled whether these three factors are needed for the prostate in long‐term cultures.
A scanning electron microscope survey of the origin of the primordial pronephric duct cells in the avian embryo
Authors: Jarzem Jacquelyn , Meier Stephen P.
Published: February 2005

In the avian embryo, the pronephric duct derives from the anterior part of a ridge that develops just lateral to the somites and segmental plate. The ridge extends from the sixth somite to Hensen's node and begins to form as the sixth somite is condensing. By the nine‐somite stage, the cranial end of the ridge (for a length roughly equivalent to four or five somite diameters) is seen as a duct primordium of smooth, elongated cells that resemble the migrating cells of the caudal tip of the duct as it extends to the cloaca. These cells show a decreased attachment to the fibers of the interstitial matrix and an increased adhesion to other duct cells. By 10 somites, there is a well‐formed pronephric duct rudiment at a time when the pronephric tubules have not yet begun to develop. Therefore, the avian pronephric duct has a separate origin from the pronephric tubules and may play an inductive role in the formation of pronephric tubules.
Shaping of the chick neuroepithelium during primary and secondary neurulation: Role of cell elongation
Authors: Schoenwolf Gary C. , Powers Monica L.
Published: February 2005

Cell elongation is a cardinal event in formation and shaping of the neuroepithelium during both primary and secondary neurulation. This study had three purposes. The first was to clarify the role of microtubules in maintaining the elongated configurations of chick neuroepithelial cells. Neuroepithelial cells of the neural plate (the rudiment of the primary neural tube) and medullary cord (the rudiment of the secondary neural tube) reduced their heights an average of approximately 25% when their microtubules were depolymerized, but most cells remained considerably elongated and columnar. Complete rounding up occurred only as cells entered metaphase where they arrested. These results suggest that microtubules as well as other factors are required to maintain the fully elongated configurations of cells composing epithelial sheets. The second purpose of this study was to evaluate the hypothesis that neuroepithelial cell elongation plays a major role in narrowing of the neural plate. To do this, the width of the neural plate was examined after microtubule depolymerization and repolymerization. As the heights of neuroepithelial cells decreased with loss of their microtubules, the width of the neuroepithelium increased roughly proportionately; subsequent repolymerization with concomitant cell elongation resulted again in neural plate narrowing. Thus, the hypothesis is supported. The third purpose of this study was to examine the roles of cell rearrangement and change in neuroepithelial cell or extracellular volume in neural plate narrowing and extension. Extensive cell rearrangement, resulting in net cell loss from the width of selected, representative levels of the neural plate, does not seem to play a major role in plate narrowing, but decreases in cell or extracellular volume are likely involved. Further studies are necessary to complete our understanding of the mechanisms driving neural plate shaping and bending.
Physiological role of skeletal muscle glycogen in starved mice
Authors: Sakaida Minoru , Watanabe Jun , Kanamura Shinsuke , Tokunaga Hirohiko , Ogawa Ryokei
Published: February 2005

To study the physiological role of skeletal muscle glycogen in starved animals, effects of starvation on glycogen and glycogen phosphorylase (EC 2.4.1.1.) activity were studied in muscle fibers (morphologic study) and in whole muscles (biochemical study) of the rectus femoris muscle of mouse. Glycogen content in the liver of the starved animals was also measured. PAS reaction, strong in muscle fibers of fed animals, became weak predominantly in type IIB fibers after 2 days and almost disappeared after 4 days of starvation. Glycogen particles, numerous in the sarcoplasm between myofibrils of muscle fibers, decreased markedly predominantly in type IIB fibers after 2 days and almost disappeared after 4 days. Phosphorylase a activity, undetected in fibers of fed mice, appeared weak in type IIB fibers and very weak in type IIA fibers after 2 days and became moderate in type IIB fibers and weak in type IIA fibers after 4 days. Muscle glycogen content did not differ by 16 hours from the values of corresponding fed animals. However, liver glycogen content had already decreased after 8 hours and markedly so after 12 hours. The results support our hypothesis—“skeletal muscle glycogen is used for maintaining the blood glucose level in starved mice” (Hirose et al.: Anat. Rec., 216:133–138, 1986)—and show that type IIB fibers play a main role in maintaining the glucose level and that muscle glycogen is utilized after depletion of liver glycogen.
Comparative development of gastrin and somatostatin cell populations in the pancreas, stomach, and duodenum of the rat during the perinatal period
Authors: Onolfo Jean Philippe , Lehy Thérése
Published: February 2005

The comparative growth patterns of endocrine gastrin and somatostatin cell populations were examined in the rat, during the perinatal period, to investigate possible relationships between their development and that of gastric acid secretion, gastrin and somatostatin hormones being implicated in the regulation of acid secretion. Total cell populations were estimated daily in the pancreas, stomach, and duodenum, by using a quantitative morphological method, from 19 days postcoitum to 8 days postpartum.

In the pancreas, both cell types were present at 19 days postcoitum. After increasing, gastrin cells abruptly dropped from 4 days postpartum, while somatostatin cells continued to increase. In the stomach, gastrin cells seemed to appear at 19 days postcoitum, increasing with age. Somatostatin cells appeared only after birth and could be precisely quantified from 4 days postpartum. In the duodenum, the two cell types were present in similar numbers at 19 days postcoitum and increased similarly with age.

Comparison of gastrin and somatostatin cell developmental behavior with previous data on the ontogeny of acid secretion shows a parallelism between the appearance of basal H+ fluxes at 20–21 days postcoitum and the high daily multiplication of the gastrin cell number in the three organs. Additionally, the marked decrease of pancreatic gastrin cell population at 4 days postpartum and the simultaneous development of the gastric somatostain cell population might explain, among other mechanisms, the diminution of gastric acid secretion noted after birth.
The effect of nerve section on the incidence and distribution of gap junctions in the odontoblast layer of the cat
Authors: Holland G. R.
Published: February 2005

Gap junctions are numerous in the odontoblast layer of the dental pulp and may link sensory axons to odontoblasts. If these junctions do link axons and odontoblsts, they, together with the axons, should disappear after cutting the pulpal nerves centrally. Under general anesthesia the inferior alveolar nerve on one side of two young adult cats was sectioned. Under general anesthesia the animals were perfused with fixative 56 hours later and the coronal dental pulp prepared for electron microscopy. Ultrathin sections were examined from the level of the pulpal cornu and levels approximately one, two, and three mm below this. The incidence of cell processes and gap junctions was measured at different distances from the pulp predentin junction, and operated and control sides compared.

The odontoblast layer at the level of the cornu differed from elsewhere in having, on the control side, a greater density of cell processes and gap junctions and in having clearly recognizble axons approaching to within 5 to 10 μm of the predentin. The only statistically significant changes after nerve section occurred in this layer and consisted of a decline in the incidence of cell processes and of gap junctions that link one cell process to another. There was no significant difference between the operated and control sides in the number of gap junctions linking cell processes to recognizable cell bodies.

The odontoblast layer in the pulpal cornu contained substantial numbers of unsheathed axons, many presumably en route to the dentin. These axons may participate in gap junctions that link them to other cell processes, possibly even other axons. No clear evidence was found of junctions involving axons and identifiable odontoblast cell bodies.
Effect of surgical sympathectomy on bone remodeling at rat incisor and molar root sockets
Authors: Sandhu H. S. , Herskovits M. S. , Singh I. J.
Published: February 2005

Sympathectomy was carried out in 4‐week‐old Sprague‐Dawley rats by unilateral surgical removal of the superior cervical ganglion. Sham‐treated rats served as controls. All rats were injected with tetracycline hydrochloride at surgery as well as 36 hr prior to sacrifice. Rats were killed at 7, 14, or 21 days following sympathectomy. Mandibular periosteal and endosteal surfaces were analyzed by fluorochrome morphometry. Osteoclasts were identified by acid phosphatase staining, and incisor and molar root sockets were analyzed morphometrically. Following sympathectomy, periosteal and endosteal apposition as well as the rate of mineralization were significantly lower. At the same time, a significant increase in the number of osteoclasts per socket as well as in active and inactive bone resorption surfaces was also seen. All parameters, however, returned to normal values 2–3 weeks after sympathectomy. The data provide the first direct quantitative evidence that sympathetic neurons modulate bone resorption and bone remodeling in vivo.
Expression of type I and III collagen during morphogenesis of fetal rat testis and ovary
Authors: Paranko Jorma
Published: February 2005

The distribution of interstitial collagen type I and III was studied immunocytochemically and ultrastructurally in the fetal rat testis and ovary from the undifferentiated stage (day 12) until birth. The results suggest that there is a correlation between the differentiation, organization, and abundance of the mesenchyme and the differentiation of the testicular vs. ovarian cords. Type III collagen was already present in the undifferentiated gonadal mesenchyme, and it appeared at an early stage around the organizing gonadal cords. Type I collagen appeared later in a similar mesenchymal distribution as type III collagen. Fragmentation of the subepithelial basement membrane in the gonads starting morphogenesis was considered to indicate that the surface epithelium participates in the gonadal cord formation. The expression of type III collagen at first on the surface of the developing testicular cords and later around the ovarian cords suggests that the mesenchymal premyoid cells are actively involved in the male cord formation. Focal discontinuities were found in the basement membrane of the ovarian cords, which in part were separated from each other by a ramified and relatively sparse mesenchyme. A complex linkage between the cytoskeleton and the extracellular matrix is illustrated both in the cord forming Sertoli and granulosa cells, and in the adjacent mesenchymal cells. Depletion of the mesenchyme and the basement membrane around the germ cell‐granulosa cell associations of the wide ovarian medullary cords may be causal for their subsequent degeneration.
The effects of vinblastine on the secretory ameloblasts: An ultrastructural, cytochemical, and immunocytochemical study in the rat incisor
Authors: Nanci A. , Uchida T. , Warshawsky H.
Published: February 2005

Secretory ameloblasts synthesize the organic matrix of enamel and secrete it at two distinct “putative secretory sites” characterized by membrane infoldings (Nanci and Warshawsky, 1984a). The antimicrotubular agent vinblastine sulphate interferes with secretion. We have examined the effect of this drug on the ameloblast secretory sites and re‐evaluated the effect on the intracellular organization of the cell by using conditions that optimize fixation, cytochemistry (ZIO), and immunocytochemistry. Associated with the disappearance of secretory granules and Golgi‐related structures from Tomes' process was the loss of membrane infoldings at secretory sites. The Golgi apparatus appeared fragmented and numerous granule clusters were found throughout the cell body. These clusters were often seen in relation to extracellular patches of material in which no crystallites were seen. Immunocytochemistry revealed the presence of enamel proteins in the protein synthetic organelles, including various granule types, in lysosomes and in the extracellular patches. These data suggest that ameloblasts under the effect of vinblastine carry on secretory activities, but the product is not routed to the usual sites. It was confirmed that membrane infoldings characterize the sites where enamel proteins are normally secreted.
Leydig cell differentiation during maturation of the rat testis: A stereological study of cell number and ultrastructure
Authors: Zirkin B. R. , Ewing L. L.
Published: February 2005

In an effort to further understand the basis for the changes in steroidogenesis known to occur during sexual maturation in the rat, we examined by quantitative morphologic methods the number and ultrastructure of Leydig cells in fetal rats (days 18–20 of gestation) and in rats from days 2 to 3 of age through adult. Quantitative light microscopic analyses indicated that Leydig cell number, when expressed per unit volume of testis, was very high in fetal rat testes, fell significantly in testes of days 2 to 3 rats, and subsequently rose significantly. When Leydig cell number was expressed per testis rather than per unit volume of testis, the results indicated that testes of fetal rats and rats of days 2 to 3 contained the same number of Leydig cells; after the neonatal period, significant increases in Leydig cell number per testis occurred in concert with increases in testis weight. Quantitative electron microscopic studies revealed significant differences in the ultrastructure of fetal and adult populations of Leydig cells. For example, Leydig cells of fetal and neonatal rats contained abundant lipid, whereas Leydig cells, of weeks 7 to 8 and adult rats contained little. Stereological analyses also revealed dramatic changes in smooth endoplasmic reticulum and inner mitochondrial membrane surface areas during sexual maturation, both per cell and per testis. These findings are discussed with respect to the steroidogenic capacity of the testis during sexual maturation.
Localization of immunoreactive calcitonin gene‐related peptide in thyroid C cells from various mammalian species
Authors: Kameda Yoko
Published: February 2005

Localization of immunoreactive calcitonin gene‐related peptide (CGRP) in thyroid C cells from various mammalian species was investigated by the immunoperoxidase method. In many animal species including dogs, cats, cattle, monkeys, rats, and rabbits, almost all C cells revealed an intense immunoreactivity for CGRP; the cytoplasm of C cells was filled with reaction products for CGRP. In these animal species, calcitonin and CGRP coexisted in the C cells. However, in some species including pigs, mice, hamsters, and guinea pigs, the CGRP immunoreactivity of C cells was weak or negative. It was concluded that there was a considerable variation in CGRP immunoreactivity of C cells from species to species. In rabbits and guinea pigs, almost all C cells were also intensely immunoreactive to antisomatostatin antiserum, whereas in other animal species including dogs, cats, cattle, monkeys, rats, pigs, mice, and hamsters only a few C cells were immunoreactive to somatostatin. Three peptides–calcitonin, somatostatin, and CGRP—are synthesized alone in rabbit C cells. Thus, there was no relation between CGRP and somatostatin concerning the existence of both peptides in thyroid C cells.
Bursal secretory cells: An electron microscope study
Authors: Olah Imre , Glick Bruce
Published: February 2005

In addition to lymphocytes, macrophages, and epithelial cells, the bursa medulla possesses a cell we have named the secretory cell. The secretory cell, which makes up approximately 0.5% of the bursal cell population, exhibits an eccentric nucleus with a chromatin pattern similar to that of a small lymphocyte and an elongated cytoplasm with one or more cell processes. The electron‐dense cytoplasmic granules of the immature secretory cell are localized around the cytocentrum, while in the mature secretory cell these granules are situated beneath the cell membrane of one process. The granular location endows a polarized appearance to the secretory cell. The surface of the membrane is covered with a finely spotted flocculated substance, which may originate from a granular discharge. The round, ovoid, or irregular‐shaped granules reveal a homogeneous or distinctive internal pattern. The cortico‐medullary border may be the germinal layer of the bursal medulla. The bursal secretory cell is a modified dendritic cell with possible endocrine functions that may be important in B‐cell induction.
Attachment of neural crest cells to endogenous extracellular matrices
Authors: Brauer Philip R. , Markwald Roger R.
Published: February 2005

Newly emerging neural crest (NC) cells will enter either the lateral pathway under the surface ectoderm or the vental pathway along the neural tube depending on the axial level (Pratt et al.: Dev. Biol., 44:298–305, 1975; Thiery et al.: Dev. Biol., 93:324–343, 1982; Newgreen et al.: Cell Tissue Res., 221:521–549, 1982; LeDouarin et al.: In: The Role of Extracellular Matrix in Development. Alan R. Liss, Inc., New York, pp. 373–398, 1984; Brauer et al.: Anat. Rec., 211:57–68, 1985). A number of studies have shown a correlation between the type of extracellular matrix (ECM) associated with adjacent tissues (e.g., ectoderm, neural tube, and mesoderm) and the initial pathway taken by NC cells. Our working hypothesis is that the direction of NC cell migration (ventral vs. lateral pathway) depends on the composition of the ECM associated with the surface ectoderm and its ability to support NC cell attachment. In this study, we tested this hypothesis by isolating endogenous ECM associated with the ectoderm of each region and examining the ability of each endogenous ECM to support cranial and trunk NC cell attachment in vitro. Results indicated that both cranial and trunk NC cells preferentially attached to cranial ectodermal ECM as compared to trunk ectodermal ECM. The differences in NC cell attachment were not due to a preferential adsorption of cranial ectodermal ECM onto the ECM‐conditioned plastic substrate over trunk ectodermal since approximately equal amounts of ECM bound to the plastic. These results supported the hypothesis and provide evidence that endogenous ectodermal ECM may be one factor potentially responsible for directing the NC cells along a ventral or a lateral pathway.
Effects of colchicine on the shape of chick neuroepithelial cells during neurulation
Authors: Fernandez J. G. , de Paz P. , Chamorro C. A.
Published: February 2005

We have analyzed the effects of colchicine on the cell shapes in chick neuroepithelium. Cell shapes were ascertained by the position of the nucleus in plastic serial sections. We tested three colchicine doses (5 × 10−5 M, 5 × 10−6 M, and 5 × 10−7 M) by two experimental treatments (in ovo and in vitro). Colchicine treatment in vitro is always effective in depolymerizing microtubules of neuroepithelial cells and reduces the percentages of wedge‐shaped cells in the median area of neuroepithelium. The same effect can be observed when the embryos are treated with 5 × 10−5 M or 5 × 10−6 M colchicine in ovo. A concentration of colchicine of 5 × 10−7 M in ovo cannot disrupt microtubules in stage 8 and stage 10 embryos, and the percentage of wedge‐shaped cells is the same as that of the untreated cells. In stage 6 embryos this colchicine dose effects the microtubules and the percentages of wedge‐shaped cells. These facts are interpreted in respect to variations in microtubular resistance to microtubular‐disrupting agents that are shown by the neuroepithelial cells from different developmental stages.
Loss of sensory neurons after sciatic nerve section in the rat
Authors: Schmalbruch Henning
Published: February 2005

In this study, the loss of sensory neurons in the rat was assessed after sciatic nerve section hat birth and at 4 weeks of age. The neuronal defict in ganglia L4–L6, 39–89 weeks after neonatal denervation, was 10,000–17,000. The nerve contains about 19,000 afferent axons, so some axotomized neurons survived. Degenerating perikarya were absent, probably because all surviving neurons had reestablished target contacts. Sectioning the nerve at age 4 weeks, in five rats, after 19–92 weeks had caused the death of 7,000–11,500 neurons. Whether the nerve regenerated or not in these rats apparently did not influence the extent of neuron death. Nevertheless, no deficit was observed in a sixth rat in which muscle reinnervation was very good. Therefore, the results are inconclusive with respect to the effect of axonal regeneration. Ganglia of rats operated at age 4 weeks regularly contained perikarya with axonal reaction; this supports the notion that some mature neurons are able to permanently survive without target contact. There was no evidence for selective loss of large or small neurons after nerve section at birth or at age 4 weeks.

The extent of cell loss in individual ganglia varied, indicating varying contributions of the three ganglia to the nerve. Hence, it is not possible to quantify the effect of experimental conditions on the number of sensory neurons when only one of the several ganglia contributing to the nerve is investigated.
Maturation changes of the plasma membrane of rat spermatozoa observed by surface replica, rapid‐freeze and deep‐etch, and freeze‐fracture methods
Authors: Toyama Yoshiro , Nagano Toshio
Published: February 2005

Rat spermatozoa from the epididymis and ductus deferens were observed by surface replica, rapid‐freeze and deep‐etch, and conventional freeze‐fracture methods. By the surface replica method, parallel periodical ridges were observed in the acrosomal region of the spermatozoa from the distal part of the cauda epididymis (zone 6) and from the ductus deferens. The periodicity of the ridges forming a domain was about 35 nm. A quantitative analysis of the spermatozoa along the reproductive tract indicated that 39.4% and 73.5% of the population in zone 6 of the epididymis and in the ductus deferens, respectively, had the domain. None of the spermatozoa from zone 1 through zone 5 had the domain. The results of the rapid‐freeze and deep‐etch procedure showed that the ridges observed by the surface replica method consisted of linear arrangements of elliptical particles on the ES face of the plasma membrane. The particles were about 30 nm in length and 15 nm in width. On the corresponding PF face of the plasma membrane, linear arrangements of the intramembrane particles (IMPs) of about 8 nm in diameter were observed by both the deep‐etch and freeze‐fracture methods. The IMPs tended to run in paired parallel lines. A close relationship was observed between the lines of the elliptical particles on the ES and of the IMPs on the PF faces. The elliptical particle may be a protruded part of the IMP(s) or other protein(s) bound to the IMP(s).
Removal of collagen bundles in murine uterus during postpartum involution
Authors: Shimizu Kiyoshi , Hokano Masami
Published: February 2005

The localization of collagenolytic activity within the tissue compartments of the mouse uterus was investigated during postpartum involution. The rate of collagenase activity was measured by analysis of tissue levels of hydroxyproline from the day of parturition to the 10th postpartum day. Collagen bonding was analyzed by viewing birefringence induced by the picrosirius red‐binding technique. An attempt was made to interrelate quantitative analysis with the histologic distribution of collagen during postpartum days 1–10.

Histologic and quantitative evidence indicated the following: (1) The collagenous compartments of the endometrium and myometrium differ in their response to the postpartum rise in collagenase activity; collagen degradation occurs primarily in the endometrium, that is, the myometrial collagen remains, but much of the endometrial collagen is removed. (2) Endometrial collagen is degraded particularly in the immediate subluminal compartment.
Pathological changes in cerebral arteries following experimental subarachnoid hemorrhage: Role of blood platelets
Authors: Clower Ben R. , Yoshioka Junji , Honma Yutaka , Smith Robert R.
Published: February 2005

The role of blood platelets in producing early intimal changes in cerebral arteries following subarachnoid hemorrhage (SAH) was examined by using 18 cats. Experimental SAH was produced by a rupture of the proximal portion of the right middle cerebral artery. Following SAH, the scanning electron microscope revealed that structural alterations in the intimal layer of major cerebral arteries occurred as early as 2 hours and became more severe by 48 hours. Vascular alterations, which were predominantly detected in the ruptured vessel, consisted of endothelial cell corrugation, detachment, crater formation, intimal adhesion of platelets and red blood cells, intimal thrombi, and reendothelialization. When cats were pretreated prior to SAH with an anti‐platelet‐aggregating agent, OKY‐1581, the intimal blood elements and thrombi were clearly reduced, and reendothelialization was not observed. However, endothelial cell changes in the OKY‐1581‐treated group were very similar to those occurring in the nontreated group. While these results suggest that bioactive substances contained within blood platelets, such as growth factors, serotonin, and norepinephrine, have little effect on producing endothelial cell injury, platelets may be important in the initiation of reendothelialization following vessel injury.
Surface coat material associated with the developing otic placode/vesicle in the chick
Authors: Sinning Allan R. , Olson Mark D.
Published: February 2005

Surface coat material (SCM) has been illustrated in association with the apical surfaces of numerous epithelia during morphogenesis. This study investigates the development of a SCM associated with the invaginating otic placode/vesicle in the chick. Glycoconjugate containing SCM was retained by the inclusion of cetylpyridinium chloride (CPC) in the fixative, histochemically visualized by using ruthenium red (RR) staining, and viewed by scanning (SEM) or transmission (TEM) electron microscopy. Initial characterization of the glycoconjugates present in this material was elucidated by using lectins conjugated to fluorescein isothiocyanate. Lectins utilized included concanavalin A (Con A), wheat germ agglutinin (WGA), and soybean agglutinin (SBA). Invagination of the otic placode was apparent as early as stage 12. By stage 15 the vesicle was beginning to separate from the surface ectoderm as evidenced by its aperture, which was altered in shape and reduced in size. All embryos fixed with glutaraldehyde containing either CPC or RR were shown to possess SCM associated with the surface ectoderm, particularly in the area of the otic placode/vesicle. Additional embryos were processed by cryofixation without prior alehyde fixation; these also exhibited SCM. All lectins labelled the epithelium of the otic placode/vesicle. However, their binding patterns were not identical. The binding of Con A and WGA remained constant over the stages studied, while SBA increased as the otic vesicle developed. The data clearly indicate that otic placode morphogenesis is accompanied by the synthesis of SCM rich in glycoconjugates.
Lectin binding to the human retina
Authors: Söderström Karl‐Ove
Published: February 2005

Formalin‐fixed, paraffin‐embedded tissue sections of the human retina were stained with different fluorescein isothiocyanate‐conjugated lectins. The lectins used were concanavalin A (Con A), Triticum vulgaris (WGA), glycine maximum (SBA), Dolichos biflorus (DBA), Ulex europaeus (UEA I), Arachis hypogaea (PNA), and Ricinus communis (RCA I).

Con A stained both the inner and outer segments of the rods and cones, whereas WGA stained the inner and outer segments of the rods and the outer segments of the cones. PNA selectively stained only the inner segments of the cones. In addition, Con A and WGA stained neuron cytoplasm and nerve fibers in different layers of the retina. The results obtained differ in some important aspects from those previously obtained in the frog and monkey retina; this finding may be due to species differences. The results of lectin staining in the normal human retina may form the basis for future studies of retinal diseases.
Earliest enamel deposits of the rat incisor examined by electron microscopy, electron diffraction, and electron probe microanalysis
Authors: Landis William J. , Burke Grace Y. , Neuringer Julia R. , Paine Mary C. , Nanci Antonio , Bai Paul , Warshawsky Hershey
Published: February 2005

In order to describe initial events in enamel mineralization and to help characterize inorganic‐organic interactions in this tissue, the earliest rod and interrod enamel in mandibular incisors from normal young adult (100 gm) rats, perfused with 100% ethylene glycol, has been studied by transmission electron microscopy, selected area electron diffraction, and high‐spatial‐resolution electron probe microanalysis. Diffraction and probe data were correlated precisely from the same extracellular regions of the tissue. Sites were examined progressively as a function of location (a) from the most recently deposited enamel adjacent to ameloblasts toward the dentin‐enamel junction and (b) from the apical portion of the tooth longitudinally toward its incisal end. Electron diffraction patterns consistent with that of a poorly crystalline hydroxyapatite were generated at all locations. Diffraction characteristics changed only slightly toward that of more crystalline hydroxyapatite at different locations. Earliest apical enamel generated molar Ca/P ratios in a range of 0.99–1.46 (average 1.24 ± 0.15). Molar Ca/P ratios of the first enamel interrod elements increased from ∼1.24 at ameloblast‐enamel boundaries to ∼1.40 at the dentin‐enamel junction, small changes corresponding to those observed in electron diffraction characteristics.
High glucose‐6‐phosphatase activity in osteoblasts in the metaphysis of femur of growing rats
Authors: Tokunaga Hirohiko , Kanamura Shinsuke , Watanabe Jun , Kanai Kazuo , Sakaida Minoru
Published: February 2005

Glucose‐6‐phosphatase (G6Pase) activity was examined cytochemically in the metaphysis of femurs of 3− and 7‐day‐old rats. G6Pase and hexokinase activities were also examined biochemically in the femur and tibia of 3‐day‐old animals. The reaction product for G6Pase activity was seen in the endoplasmic reticulum and nuclear envelope of all cell types composing the metaphysis. The amount of the reaction product was abundant in osteoblasts, moderate in osteocytes, and moderate to scarce in osteoclasts and capillary endothelial cells. Biochemical G6Pase activity in the bones was higher than that in the brain, submandibular gland, or pancreas of the animals. Hexokinase activity in the bones was not different from that in the submandibular gland, pancreas, or kidney. The activity ratio of G6Pase and hexokinase in the bones (0.603) was greater than that in the submandibular gland, pancreas, or brain and smaller than that in the kidney. Possible physiological significances of the higher G6Pase activity in osteoblasts are discussed.
Effects of various insulin dosages on hepatic lipogenesis
Authors: Drake Richard L.
Published: February 2005

Insulin treatment of diabetic rats fed a high‐carbohydrate, fat‐free diet produces a dramatic accumulation of hepatic lipids. However, this increase in hepatic lipids may only be a response to injections of exceptionally high doses of insulin. This study addresses this possibility. Alloxan‐diabetic rats, fed a high‐carbohydrate, fat‐free diet, were given insulin every 12 h for 60 h at the following dosages: 1/2 unit each, 1 unit each, 2 units each, and 4 units each of regular and NPH insulins. At the end of the treatment period, liver samples were collected and used for morphological and biochemical analyses. Histologic examination revealed hepatic lipid accumulations at all insulin doses; the amount of lipid increased until maximal levels were reached at an insulin dosage of 1 + 1, which was maintained at doses of 2 + 2 and 4 + 4. Thus, hepatic lipid accumulation occurs regardless of the dosage of insulin administered to the diabetic animal. It is not simply an abnormal cellular response to excessive hormone levels. Similarly, the activity of the hepatic lipogenic enzyme, malic enzyme, increased at initial insulin dosages and reached maximal levels at 2 + 2. However, in contrast to lipid accumulation, enzyme activity decreased at the final insulin dosage of 4 + 4. Thus, there appears to be a direct relationship between increasing insulin levels and malic enzyme activity until an optimal insulin concentration is reached. After this point, excessive insulin levels do inhibit malic enzyme activity.
Long‐term reiention of regenerative capability after denervation of skeletal muscle, and dependency of late differentiation on innervation
Authors: Gulati Adarsh K.
Published: February 2005

The present study examines the influence of denervation on the regenerative ability of skeletal muscle in rats. Muscle denervation was achieved by transecting and ligating the cut ends of the sciatic nerve. Four to 48 weeks after denervation, the extensor digitorum longus (EDL) muscle was autotransplanted to induce muscle regeneration. The transplanted EDL muscles were examined at 1–12 weeks. Normal (i.e., no prior denervation) EDL muscle autotransplants were also examined for comparison. Denervation resulted in progressive atrophy of muscle, marked by a reduction in the size of myofibers and an increase in endomysialperimysial connective tissue. In spite of these alterations, typical events of muscle regeneration were invariably observed after transplantation. Initial myofiber degeneration and subsequent regeneration of myotubes occurred in a manner similar to normal muscle transplants. However, only a partial maturation of myotubes was observed in denervated muscles. These results show that extended denervation does not abolish the capability for muscle regeneration. The precursor myosatellite cells, proposed to be responsible for muscle regeneration, retain their regenerative potential after denervation. It is concluded, however, that the presence of intact innervation is crucial for the terminal differentation and maturation of regenerating muscle.