bluuebunny/crossref_metadata_2025 huggingface dataset:
The micocirculation of bone and marrow in the diaphysis of the rat hemopoietic long bones
Authors: De Saint‐Georges L. , Miller S. C.
Published: February 2005

The nature of the microcirculation of the diaphyseal portion of long bones and the adjacent bone marrow is poorly understood. The purpose of this study was to describe the blood supply in the diaphyseal cortex and the relationship of the bone vascular circulation to that of the bone marrow in the growing rat. India ink‐gelatin was infused in the arterial system of 3‐month‐old rats and the vascularization was determined from histological sections. In some studies the periosteal circulation was blocked but the nutrient and metaphyseal arteriole systems were left intact. In the growing rat, most of the vascular flow appears to be centripetally through the diaphyseal cortex and this appears to be the primary blood supply for the adjacent bone marrow. The India ink traversed the cortex and entered the marrow through osteal canals at the endocortical surface. At the marrow‐endocortical bone surface interface, ink exiting from the osteal canals filled the adjacent marrow sinusoids in what appeared as “bush‐like” structures. From the bone marrow the ink appeared to drain into the central vein. Some arterioles from the nutrient system were found to penetrate the inner two thirds of the cortical bone and then re‐enter the bone marrow. The centripetal flow of blood and the importance of the cortical flow for perfusion of the hemopoietic tissue was further documented when periosteal flow was obstructed. In this situation, the cortical bone and adjacent bone marrow were not perfused while the nutrient system and central vein were filled with ink. These results show that in the growing rat, the diaphyseal circulation is almost entirely centripetal and the adjacent hemopoietic tissues are perfused mostly with blood that must first traverse the cortical bone. © 1992 Wiley‐Liss, Inc.
Skeletal malformations in hatchery reared Rana perezi tadpoles
Authors: Martínez Irene , Álvarez Rafael , Herráez Inmaculada , Herráez Paz
Published: February 2005

Skeletal malformations at metamorphosis in Rana perezi tadpoles reared in culture have been studied. Tadpoles were fed ten artificially compounded and fresh diets and kept at two different temperatures. Animals were maintained in fiberglass tanks. Bone damages are related to the nourishment with compound diets. Tadpoles fed such diets showed variable percentages of scoliosis, kyphosis, luxations, and subluxations in the hind limbs, aplasia in phalanges, and wide failures of ossification. The data suggest the origin of the lesions is a deficiency in some compounded diets that could alter collagen metabolism during skeletal adjustments at metamorphosis. © 1992 Wiley‐Liss, Inc.
The surface lamina of the articular cartilage of human zygapophyseal joints
Authors: Giles L. G. F.
Published: February 2005

Literature referring to the conflicting results of investigations into the possible existence and composition of the lamina splendens is reviewed. Two hundred micrometer thick histological sections from 80 human cadaveric lower lumbar zygapophyseal joint articular cartilages were examined by ordinary light and darkfield microscopy. The findings illustrate what appears to be an acellular surface lamina on the opposing cartilaginous surfaces. No speculation is made regarding the possible physiological significance of the lamina based on this anatomical study. © 1992 Wiley‐Liss, Inc.
Insulin improves survival but does not maintain function of cultured chick wing bud apical ectodermal ridge
Authors: Boutin Eugenie L. , Fallon John F.
Published: February 2005

Previously we demonstrated that high levels of insulin (5 μg/ml) permit the survival of isolated chick apical ectodermal ridge in culture (Boutin and Fallon, Dev. Biol., 104:111–116, 1984). Here we address whether lower levels of insulin or insulin‐like growth factors (IGFs) can also improve the survival of cultured apical ectodermal ridge and whether ridge function is maintained along with ridge survival. Neither IGF I nor IGF II (100 ng/ml) decreased ridge cell death; however, cell death was significantly decreased with 50 ng/ml insulin. No further improvement was obtained in the presence of both IGF I and insulin. These data suggest that insulin improved the survival of the isolated apical ectodermal ridge by binding its own receptor. To test for the maintenance of function, stage 20 ridges were cultured for 0, 6, 12, 18, or 24 hr with or without insulin (5 μg/ml or 5 ng/ml) and used to make recombinant limbs. Isolated ridges cultured for 12 hr or more produced fewer outgrowths and these were rarely distally complete. The medium in which the ridges had been cultured did not influence ridge activity, despite the major differences in cell survival. Recombinants made with ridges cultured with limb mesoderm for 18 hr did not yield outgrowths as often as those with freshly isolated ridges, but most of the limbs that did form were distally complete. These results suggest that the decline in function of cultured, isolated apical ectodermal ridge was not due merely to ridge cell death but rather, at least in part, to its separation from limb mesoderm. © 1992 Wiley‐Liss, Inc.
Chondroclasts and endothelial cells collaborate in the process of cartilage resorption
Authors: Lewinson Dina , Silbermann Michael
Published: February 2005

The condylar cartilage of the young rat is a major growth center of the craniofacial complex. Differences between the mechanism that results in bone formation from growth centers in the epiphyseal plates of long bones are dictated primarily by the different character of the mineralization of the cartilage. In this ultrastructural study we demonstrate that the terminal hypertrophic chondrocytes undergo apoptosis and disintegration while simultaneously chondroclasts dissolve gaps in the calcified cartilage that engulfs them. The latter are also phagocytizing debris of the chondrocytes. The chondroclasts are intimately followed by tube‐forming endothelial cells that most probably coalesce to create extensions of the invading capillaries into the evacuated lacunae. The chondroclasts have ultrastructural features similar to osteoclasts. They are multinucleate, are rich in mitochondria and vacuoles, form clear zones that adhere to the spicules of the calcified cartilage, and also form a sort of ruffled border. The latter is not as elaborate and orderly arranged as is known from osteoclasts. The capillaries that follow orient the stroma cells to the evacuated lacunae and, together with the calcified cartilaginous scaffold, supply the adequate environmental conditions for the stroma cells to differentiate into osteoblasts and to build up trabecular bone. © 1992 Wiley‐Liss, Inc.
Reinitiation of gonocyte mitosis and movement of gonocytes to the basement membrane in testes of newborn rats in vivo and in vitro
Authors: McGuinness Michael P. , Orth Joanne M.
Published: February 2005

Movement of postnatal gonocytes to the periphery of the seminiferous cord, where they contact the basement membrane, and resumption of mitosis by these previously quiescent cells are likely to be critically important in establishing spermatogenesis in neonatal rats. We used several approaches both in vivo and in vitro to determine precisely when each of these two events begins, to study their temporal relationship to each other, to determine whether gonocyte division is a prerequisite for relocation or vice versa, and to probe the source of factors initiating and/or regulating these events. Both light and electron microscopy were used to determine that the first gonocytes make contact with the basement membrane on postnatal day 4, while quantitative autoradiography following 3H‐thymidine administration in vivo indicated that the first gonocytes to re‐initiate cell division do so one day earlier, on day 3, and that the percentage of gonocytes dividing remains at a stable level through day 5. Moreover, we organ‐cultured neonatal testes from birth onwards in the presence of defined, serum‐ and hormone‐free medium and determined that both proliferation and relocation of gonocytes begin and continue in vitro as in vivo. This observation argues against involvement of extratesticular factors in stimulating gonocyte relocation and division, and points to the testis itself as the most likely source of agent(s) regulating postnatal maturation of these cells. In other, similar incubations we included 3H‐thymidine for varying periods of time to label either those gonocytes that are the first to divide or all gonocytes that divide during the first 48 hr of culture. From these studies, we confirmed that the first gonocytes to divide do so while separated from the basement membrane and found that, although some cells divide before moving peripherally, others do not. © 1992 Wiley‐Liss, Inc.
Evidence that hepatocytes can phagocytize exogenous substances
Authors: Soji Tsuyoshi , Murata Yoshio , Ohira Akihiro , Nishizono Hisanori , Tanaka Mitsuru , Herbert Damon C.
Published: February 2005

Although the phagocytic action of Kupffer cells is well known, such a phenomenon has not been well documented for hepatocytes. Follwing the injection of a suspension of egg lecithin‐coated silicon particles (0.5–1.5 μm in diameter) into the portal vein of rats, Kupffer cells showed minimal phagocytotic action, which was in contrast to the hepatocytes which displayed numerous phagocytized silicon particles. By comparison, when noncoated silicon particles of the same diameter as those that were coated were injected into the portal vein, the opposite observation was made. There was no uniformity in the ability of the hepatocytes to phagocytize either coated or noncoated particles from one lobule to another. Some showed active phagocytosis, while in others no evidence of such a process was observed. These data provide strong evidence for the selective phagocytic action of liver hepatocytes. © 1992 Wiley‐Liss, Inc.
Nuclear membrane modifications in polytene nuclei of Drosophila melanogaster. Serial reconstruction and cytochemistry
Authors: Park Paul C. , De Boni Umberto
Published: February 2005

The nuclear envelope of polytene nuclei of salivary glands of Drosophila melanogaster displays modifications consisting of nuclear envelope invaginations (NEI) and evaginations (NEE). Ultrastructural analyses combined with three‐dimensional reconstruction and cytochemistry show that NEI are bounded by a single membrane and that they may arise as invaginations of the inner nuclear membrane. NEI extend deeply into the nucleus. The lumens of NEI may collapse resulting in membranous sheets which may combine with those arising from adjacent NEI to form intranuclear structures resembling annulate lamellae. All NEI are associated with NEE. In contrast to NEI, NEE are enclosed in a double membrane morphologically identical to the nuclear envelope. While NEI and NEE share wheat germ agglutinin binding properties with the nuclear envelope, they differ in their ability to localize lanthanum. Pore annuli of NEI display complete lack of lanthanum binding, while those of NEE exhibit minor deposition of this cation. In contrast, pore annuli of the nuclear envelope are specifically and significantly decorated by lanthanum. A conceptual model based on the results obtained suggests that NEI are formed by invaginations of the inner nuclear membrane, together with accompanying modifications of pore complexes. © 1992 Wiley‐Liss, Inc.
Lymphatic vessels of the human dental pulp in different conditions
Authors: Marchetti C. , Poggi P. , Calligaro A. , Casasco A.
Published: February 2005

The characteristics of the lymphatic vessel endothelial wall have been investigated in human normal and inflamed dental pulps. In normal pulps the endothelial wall is characterized by the presence of micropinocytotic vesicles and intraparietal channels. In the inflamed pulpal tissue, where an increase in interstitial fluid pressure occurs, the distended endothelial wall presents open junctions between endothelial cells and the openings of the intraparietal channels. Moreover the micropinocytotic vesicles disappear. The cytoplasm of the endothelial cells is characterized by the presence of numerous Weibel‐Palade bodies, which increase in number in the dilated vessels. In the fibrillar apparatus surrounding the lymphatic vessel wall collagen fibrils are the prevalent component, while elastic fibers are not present.

The different morphological properties of the lymphatic vessels are compared and discussed with regard to the variation of the functional conditions of the tissue. © 1992 Wiley‐Liss, Inc.
Tubule formation and elemental detection in developing opossum enamel
Authors: Stern Doris N. , Song Min J. , Landis William J.
Published: February 2005

Most marsupials and some placental mammals possess enamel characterized by the presence of tubules, and the cellular origin of these structures has been the subject of a number of previous studies (See, for example, Lester, 1970; Azevedo and Goldberg, 1987). In the present report, tooth germs of the American opossum were examined to determine the structure and composition of enamel tubules during development and to analyze the enamel matrix relative to that of placental mammals with atubular enamel. For this purpose, tissues prepared by aqueous (decalcified and undecalcified) and anhydrous (undecalcified) methods were investigated by conventional transmission (TEM) and high voltage electron microscopy (HVEM), as well as by electron probe x‐ray microanalysis (EPMA), selected‐area electron diffraction (SAED), and electron spectroscopic imaging (ESI).

Results indicate that most enamel tubules in the opossum begin as cytoplasmic remnants of Tomes' processes of ameloblasts. During development of the matrix, some of the tubules do not appear to be continuous throughout the prismatic layer. Sulfur is detectable around the lumen of the tubule in decalcified sections by EPMA and in and around the tubule by ESI. Calcium/phosphorus (Ca/P) molar ratios of the mineralizing matrix are generally higher than those found in enamel of other mammals and appear to decrease rather than increase with enamel maturation. The summary of data indicates the presence of sulfated glycoproteins or proteoglycans in this tissue, specifically around enamel tubules. Calcium and phosphorus are also present within the tubules, with the sulfated groups possibly binding calcium to prevent mineralization of the enamel tubules themselves. © 1992 Wiley‐Liss, Inc.
Reproduction in a South American mouse, Abrothrix longipilis
Authors: Pearson Oliver P.
Published: February 2005

Approximately 700 Abrothrix longipilis were trapped in Argentina, and their reproductive organs were studied. Some were kept briefly in captivity. Males have the same body length as females but are 8% heavier. Sexually immature males are shorter and lighter than breeding males of the same age. Few individuals in the wild live as long as two years. All overwintering males come into breeding condition in the spring and become infertile in the autumn. All overwintering females have open vaginas in the spring, and most undergo several infertile ovulatory cyles, probably without copulating, before they become pregnant. Corpora lutea of the sterile cycles accumulate; there may be as many as 28 in a pair of ovaries. The average number of ova shed per cycle is 4.66; average litter size is 3.85. Ovulation is spontaneous. There is postpartum ovulation and fertilization without intervening sterile cycles but with maintenance of old corpora lutea.

Unusual architecture of the penis and vagina may result from unusual timing of hormone production during development, and the disjunction of ovulation and fertilization may similarly result from hormonal heterochrony at the beginning of the breeding season. The apparently nonadaptive wastage of ova in sterile cycles may be a novel example of kin selection. © 1992 Wiley‐Liss, Inc.
Anatomy and developmental chronology of the rat inferior alveolar nerve
Authors: Johansson Carina S. , Hildebrand Claes , Povlsen Bo
Published: February 2005

This report describes the anatomy of the inferior alveolar neuroascular bundle in the adult rat and provides a quantitative analysis of the developing inferior alveolar nerve (IAN). Soon after its entrance in the mandibular canal, the IAN splits into a mental nerve (MN) and an inferior dental nerve (IDN), which course in separate bony compartments. The MN passes unbranched through the mandibular canal. The IDN sends branches to the incisor, the first molar, and the second molar. The third molar (M3) is supplied by a separate IAN branch. The adult rat IAN contains 8,000–10,000 axons, 70% of which are myelinated. The MN accounts for 70% of all IAN axons, the IDN 26%, and 4% form the M3 branch. The proportion of large myelinated axons is lower in the MN than in the IDN. Following chemical sympathectomy, the IAN axon number does not change in a statistically sigificant way. The total number of IAN axons, which is high prenatally and neonatally, has decreased to the adult level about 1 week after birth. De novo myelination commences at birth and is complete 3–4 weeks later. The size spectrum of the myelinated fibres is narrow and unimodal during the first postnatal weeks. By 1 month, the largest fibres reach diameters of ∼6 μm, and a bimodal pattern is emerging. From 3 months and on, the size range reaches up to 10–12 μm, and the distribution is bimodal. These data provide a basis for further studies on developmental tooth‐nerve interactions. © 1992 Wiley‐Liss, Inc.
Comparative study of sexual dimorphism of the innominate bone in rodents and amphibians
Authors: Uesugi Yasuo , Ohta Yasuhiko , Asashima Makoto , Iguchi Taisen
Published: February 2005

Sexual dimorphism in the shape of the innominate bone was demonstrated in the rat, mouse, Chinese hamster (Cricetulus griseus), frog (Ranna nigromaculata), and newt (Cynops pyrrhogaster) with a computer‐assisted morphometric technique. In the rat, mouse, and hamster, ratios of ischium and pubis widths to the innominate bone lenght (INL) were larger in the males than in the females; however, the ratio of pubis length to INL was larger in the females than in the males. In the frog, the ratio of distance between the upper edge of the acetabulum and the lower edge of the pubis to INL was larger in males than in females. In the newt, ratios of width of ischiopubis and the longitudinal length of the ischiopubis to INL were larger in females than in males.© Willey‐Liss, Inc.
Presence of pulmonary intravascular macrophages in the equine lung: Some structuro‐functional properties
Authors: Atwal Onkar S. , Singh Baljit , Staempfli Henry , Minhas Kanwaljit
Published: February 2005

The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin‐sensitive globular coat from PIMs of calf, goat, and sheep. Monastral blue (MB) when employed as a tracer to assess the phagocytic properties of equine PIMs induced similar modification of the globules of the coat into lipid droplets, reminiscent of neutral lipids. Lipid droplets (modified coat globules) were delivered into acid phosphatase‐positive endosomes and lysosomes. Concurrently, the unaltered globules of the coat, probably internalized via fluid‐phase constitutive pinocytoses, followed a different endocytic pathway. Large‐scale platelet uptake by the PIMs was observed with thrombocytopenia in MB‐treated ponies. The possible significance of hypothetical LDL‐coat and the endocytic organelles as equivalents of synthetic apparatus of vasoactive lipids in the PIMs of horse needs to be assessed in future studies.© Willey‐Liss, Inc.
Growth of the normal human lower urinary tract from 12 to 21 weeks gestation
Authors: Cutner Alfred , Moscoso Gonzalo , Cardozo Linda , Driver Marie , Cooper Derek
Published: February 2005

Normal development of the human lower urinary tract was studied between the 14th and 20th week of gestation using 3 modes of fixation. Fixation by direct distension provides a high degree of reproducibility of parameters used to study the growth of the fetal bladder. Using this method, fetuses ranging from 12 to 21 weeks gestation were studied. Results obtained demonstrate that the length of the bladder, the inter‐ureteric distance, and the distance between the apex of the trigone and the distal tip of the urethra occur in a linear mode. Furthermore, the rate of growth of the male urethra was evidently higher when compared to that of the female from the 12th week of gestation.

Data from this work can be used for a more accurate assessment of cases with abnormal lower urinary tract development.© Willey‐Liss, Inc.
Regulation of the 12‐o‐tetradecanoyl‐phorbol‐13‐acetate‐induced inhibition of intercellular communication
Authors: Murray Sandra A. , Plummer Howard K. , Leonard Edward E. , Deshmukh Pushpa
Published: February 2005

Effects of the tumor promoter 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA) and protein kinase C (PKC) inhibitors on cell‐cell communication were studied in a normal rat liver cell line, clone 9. Communication was observed and quantitated with microspectrofluorometric and image analysis techniques following scrape‐loading of the cells with lucifer yellow. Lucifer yellow migrated as far as ten cells away from the scraped edge in control populations. Two minute TPA (25–50 μg/ml) treatment inhibited dye movement such that the dye remained mainly in the cells at the cut edge. The TPA‐induced inhibition of cell‐cell communication could be partially blocked by 15 min treatment of the cell populations with the PKC inhibitors trifluoperazine (30 μg/ml), staurosporine (2 × 10−8 or 2 × 10−6 M), sangivamycin (15 or 200 μM), or a PKC inhibitor peptide (20 μg/ml) scraped in at the same time as lucifer yellow. Normal communication was observed in cultures treated only with PKC inhibitors. Lower concentrations of TPA (50 ng/ml‐1 μg/ml) used for 2 min did not inhibit dye communication. Our results demonstrate the phorbol ester‐induced interruption of cell‐cell communication. The inhibition of PKC by inhibitors eliminates the effect of TPA on communication. Our data are consistent with a role of PKC in the control of junctional communication. © 1993 Wiley‐Liss, Inc.
Ectoplasmic (“junotional”) specializations in sertoli cells of the rooster and turtle: Evolutionary implications
Authors: Pfeiffer D. C. , Vogl A. W.
Published: February 2005

Ectoplasmic specializations are complex actin‐containing structures found at certain sites of intercellular attachment in Sertoli cells. Current evidence indicates that these structures are a form of actin‐associated adhesion junction. In the turtle (Pseudemys script) and rooster (Gallus domesticus)ectoplasmic specializations are known to occur adjacent to sites of attachment to elongate spermatids and are characterized by a layer of “loosely” cross‐linked actin filaments that lies next to the plasma membrane. In the turtle, a cistern of endoplasmic reticulum is associated with the cytoplasmic face of the filament layer. We have found that, in fixed frozen sections of turtle and rooster testes, immunological probes for myosin II react with epithelial regions that also stain with probes for filamentous actin and that are known to be sites at which ectoplasmic specializations occur. Furthermore, when exposed to standard contraction buffers, the diameters of glycerinated ectoplasmic specializations of the turtle are statistically smaller than those of the same structures exposed to control buffers. We interpret these smaller diameters as being produced by the contraction of actin bundles within the ectoplasmic specializations.

Our results indicate that ectoplasmic speializations in the rooster and turtle, unlike those in mammals, possess contractile properties. We speculate that ectoplasmic specializations in eutherian mammals may have evolved from actin‐associated adhesion junctions in which the actin bundles were initially contractile and from which myosin II was secondarily lost. © 1993 Wiley‐Liss, Inc.
Rabbit ductus arteriosus during development: Anatomical structure and smooth muscle cell composition
Authors: Giuriato L. , Scatena M. , Chiavegato A. , Guidolin D. , Pauletto P. , Sartore S.
Published: February 2005

The anatomical structure as well as the smooth muscle cell (SMC1) composition of the ductus arteriosus (DA) were studied in rabbits ranging in age from 29 days of gestation to 20 days after birth. Computerassisted, three‐dimensional reconstructions of hematoxylin‐eosin stained serial cryosections from ductus arteriosus‐aorta (DA‐AO) junctures revealed that DA in animals near term is separated from the aorta by a “septumlike” structure that is continuous with the aortic wall. Two days after birth, obliteration of DA is almost complete, and a small “pocketlike” cavity appears in the pre‐existing site in which DA merged into the aorta. This small cavity in the aortic arch was still evident in the large majority of animals examined even 20 days after birth, as also demonstrated by scanning electron microscopy. At this time period DA consisted of a central, fibrotic region surrounded by several layers of SMC (the ligamentum arteriosum, LA) and ended within the aortic media just above the small cavity, forming a round “scar.”

Vascular SMC composition of DA during closure was examined by means of indirect and double immunofluorescence procedures, using a panel of monoclonal antibodies against some cytoskeletal and cytocontractile proteins (vimentin, desmin, smooth muscle (SM), and nonmuscle (NM) myosinisoforms). “Intimal cushions” were particularly evident from 5 hr after birth and were found to be desmin‐negative, homogenously reactive for vimentin and NM myosin, and heterogeneously stained with anti‐SM myosin antibody. In SMC subjacent to the “intimal cushions,” distribution of vimentin and SM myosin was homogeneous, whereas the one of desmin and NM myosin content was heterogeneous. The cytoskeletal and cytocontractile protein content displayed by SMC during the closure of DA is similar to that of “intimal thickening” found in some pathological conditions of the arterial wall in adult rabbits. Completation of DA closure (day 2) was accompanied by the disappearance of cellular heterogeneity in myosin isoform distribution in both the “intimal cushions” and the underlying media. These results give new insights into: (1) the structure of DA‐AO juncture, which can be relevant to the physiology of blood circulation in the fetus, and (2) the phenotypic similarity of vascular SMC populations involved in the formation of “intimal cushions” and “intimal thickening”.
Morphometric analysis of the pelvis in mice treated neonatally with tamoxifen
Authors: Uesugi Yasuo , Sato Tomomi , Iguchi Taisen
Published: February 2005

The pelves of male and female C57BL/Tw mice given five daily injections of 100 μg tamoxifen, 50 μg dihydrotestosterone (DHT), or 2 μg diethylstibestrol (DES) from the day of birth were examined morphometrically and histomorphometrically. Total areas of the pelvis, ilium, ischium, and pubis were significantly smaller in neonatally tamoxifentreated mice than in the controls. There was no significant difference in length of the ischium between tamoxifen‐treated and control mice of both sexes. However, lengths of ilium and pubis, and widths of ilium, pubis, and ischium in tamoxifen‐treated male and female mice were significantly smaller than in the respective controls. In contrast, neonatal treatment with DHT or DES did not affect the shape of the pelvis of either sex. In the neonatally tamoxifen‐treated females, the number of osteoblasts and osteoclasts per 200 μm trabecular surface length and per 10,000 μm2 subperiosteal area of pubic bone section was smaller than in the controls. Inhibition of ossification persisted in the junction of the pubis and ischium of pelves treated with tamoxifen in vitro. These results suggest that neonatally administered tamoxifen mainly retards the growth of the ilium and pubis in mice by changing the activities of osteoclasts and osteoblasts, and that tamoxifen acts directly on the neonatal mouse pubis to inhibit its ossification. © 1993 Wiley‐Liss, Inc.
Sites of renin production in fetal, neonatal, and postnatal syrian hamster kidneys
Authors: Dodge Alice H.
Published: February 2005

Renin is first observed in the 14‐day fetal kidney. There is a sharp increase in the number of renin positive cells in the 15‐day fetal kidney. Renin is located in the smooth muscle cells of arteriols, interlobular arteries, and branches of the renal artery. In the neonatal kidney, the amount of renin appears to be equal to that observed in the 15‐day fetal kidney and is still located in the same blood vessels. In the 24‐hour postnatal kidney, there is a sharp decrease in the total amount of renin. Renin positive cells are now observed at the vascular pole. In the 48‐hour postnatal kidney, there is a sharp increase in the total amount of renin. Most of the renin positive cells are located at the vascular poles; however, a few renin positive cells are seen in the interlobular arteries. © 1993 Wiley‐Liss, Inc.
Reduced surface area in mitotic rounding of human chang liver cells
Authors: Sit K. H. , Bay B. H. , Wong K. P.
Published: February 2005

The rounding up of mitotic human Chang liver cells in monolayer culture was studied quantitatively. It was surprising to find significant reduction in cell surface area considering that endocytosis has been demonstrated to be at a complete standstill in M phase. Uptake studies using impermeant BCECF (2′,7′‐bis(2‐carboxyethyl)‐4(5)‐carboxyfluorescein free acid) pH indicator and particulate neutral red dye in aqueous buffer showed preferential internalization into mitotic cells in direct contrast to expectation since interphase cells do not have arrested endocytosis. However, infolded plasma membrane ruffles and internalized extracellular material were demonstrated in prophase cells, much like those seen in interphase rounding via the induction of intracellular alkalinizations. Raised intracellular pH (pHi) is a universal and consistent finding in M phase cells. Despite cessation of small pit endocytosis, it remains possible for plasma membrane internalization to be a causal factor in the observed surface area reduction in mitotic rounding. © 1993 Wiley‐Liss, Inc.
Morphogenesis in the fetal rat proximal colon: Effects of cytochalasin D
Authors: Colony Pamela C. , Conforti Jeff C.
Published: February 2005

Two major morphogenetic events, epithelial conversion and fold formation, occur in the proximal rat colon during the last week of gestation. To evaluate the role of actin microfilaments in these two developmental processes, explants from the proximal colon of 19 day fetal rats were cultured in the presence of vehicle (0.1% dimethylsulfoxide), 0.1, 1.0, or 10 μg/ml of cytochalasin D (CD) for 24–48 hr. Explants as well as 19, 20, and 21 day in vivo controls were prepared for light, fluorescence, and electron microscopy. The distribution of actin filaments was determined by rhodamine‐conjugated phalloidin binding and ultrastructural analysis of tissue fixed in the presence of tannic acid. Prior to fold formation, phalloidin binding was enhanced along the entire epithelial‐mesenchymal interface. At the onset of fold formation, focal areas of intense fluorescence appeared at irregular intervals along the base of the stratified epithelium. Within 1 day, these focal intensities were localized at the apex of small forming folds. Additional changes occurring at the epithelial‐mesenchymal interface in association with fold formation included: (1) ruffling of the previously smooth basal lamina, (2) a shape change in the subjacent mesenchymal cells from elongate to cuboidal along with the appearance of numerous processes abutting the basal lamina, and (3) a unique orientation of the associated collagen fibrils in some presumptive folds. Fold formation was inhibited in > 93% of explants cultured in the presence of 1.0 μ g/ml CD. These explants appeared to be arrested precisely at the onset of fold formation. Epithelial conversion was also incomplete in these explants. These findings indicate an active role for actin in both fold formation and epithelial conversion. © 1993 Wiley‐Liss, Inc.
Early formation of the vascular system in quail embryos
Authors: DeRuiter M. C. , Poelmann R. E. , Mentink M. M. T. , Vaniperen L. , Gittenberger‐De Groot A. C.
Published: February 2005

The relation between vascular development and translocation of the splanchnic mesodermal layers was studied in presomite to 20‐somite quail embryos by scanning electron microscopy. In addition, serially sectioned embryos were stained immunohistochemically with monoclonal antibodies (αQH1 or αMB1) specific for endothelial and hemopoietic cells.

By the formation of the foregut the anterior borders of the two splanchnic mesodermal layers of a presomite embryo are translocated to the lateral and ventral sides of the foregut and fuse in the ventral midline of a 4‐somite embryo. Meanwhile the splanchnic mesoderm differentiates into a splanchnic mesothelial layer and a plexus of endothelial cells, facing the endoderm.

From 4 somites onward the foregut is covered by a single endothelial plexus. At first the endothelial precursors bordering the anterior intestinal portal and those in the area of the ventral mesocardium lumenize, subsequently giving rise to the endocardium of the heart tube. Hereafter, the pharyngeal arch arteries and the dorsal aortae develop from the remaining precursors. During formation of the pharyngeal arches, the pharyngeal arch arteries maintain their connections with the splanchnic plexus through the developing ventral pharyngeal veins.

After disappearance of the dorsal mesocardium, the midpharyngeal endothelial strand, which is a longitudinal strand of proendocardial cells, remains connected to the foregut. This strand will contribute to the formation of the pulmonary venous drainage into the left atrium.

A bilateral accumulation of cardiac jelly developing between the promyocardium and proendocardial plexus only suggests that the heart develops from two tubes. The proendocardial layer, however, is not divided by the ventral mesocardium but initially forms just one endocardial heart tube. © 1993 Wiley‐Liss, Inc.
Effects of estradiol and progesterone on the cytodifferentiation of epithelial cells in the oviduct of the newborn golden hamster
Authors: Abe Hiroyuki , Oikawa Taneaki
Published: February 2005

The effects of estradiol and progesterone on the cytodifferentiation of epithelial cells in the oviduct of the newborn golden hamster were investigated by electron microscopy. Consecutive daily injections of estradiol‐17β (E2) induced various ultrastructural changes in undifferentiated epithelial cells of the neonatal oviduct. Ciliogenesis, formation of some ciliary buds, and ciliation were frequently observed in the oviductal epithelial cells on days 1–4 of consecutive treatments with E2. On days 2 and 3, the remaining cells contained well‐developed Golgi apparatus and rough endoplasmic reticulum. Thereafter, a few secretory granules were observed in the cytoplasm of these cells, indicative of differentiation into secretory cells. Occasionally, secretory cells undergoing ciliogenesis or mitosis were found in the epithelium. On day 9, many fully mature ciliated and secretory cells were observed. Quantitative studies clearly showed that E2 induced the differentiation of both ciliated and secretory cells. By contrast, consecutive daily injections of progesterone significantly stimulated the appearance of ciliogenic and ciliated cells but not that of secretory cells. These results indicate that the induction of differentiation of secretory cells is a specific effect of estrogen, whereas the differentiation of ciliated cells may be closely related to effect of progesterone as well as of estrogen. It is suggested that hormonal effects on differentiation differ between ciliated and secretory cells in the oviductal epithelium of the newborn golden hamster. © 1993 Wiley‐Liss, Inc.
Preservation of cardiac myocytes subjected to different preconditions: A comparative morphometric study of beating, fibrillating, and cardioplegically arrested canine hearts
Authors: Schmiedl A. , Schnabel Ph. A. , Richter J. , Mall G. , Bretschneider H. J.
Published: February 2005

This study compares the ultrastructure of beating canine hearts with that of hearts subjected to different clinically common forms of cardiac arrest. The contraction state per test field was ascertained according to a specially developed classification. The volume density of myofibrils and the surface to volume ratio of mitochondria were used as parameters for cellular and mitochondrial swelling. Contraction bands were not found in any of the differently pretreated hearts. Following immersion fixation, contractions as well as over‐ and hypercontractions in beating, fibrillating, and St. Thomas‐arrested hearts are significantly more pronounced than in HTK‐arrested hearts. Cellular and mitochondrial volumes were similar in beating and fibrillating hearts. St. Thomas‐perfusion significantly decreased cellular and mitochondrial volume compared to beating hearts, but these values were in the same range as in fibrillating hearts. Only HTK‐solution actually led to a strong reduction of these compartments. Compared to immersion, perfusion fixation after coronary perfusion with cardioplegic solutions led to comparable cellular volumes, but significantly elevated the percentage of relaxed sarcomeres and significantly reduced mitochondrial swelling. The best structural preservation of myocytes was found after HTK‐perfusion and perfusion fixation. Such ultrastructural quantitative and morphometrical parameters are powerful tools since results confirm that the degree of myocardial preservation depends on the method of cardiac arrest. This forms the basis for the choice of preconditions for subsequent ischemia. Furthermore, significant alterations of myocardial ultrastructure depend on a combination of the functional state of the heart, the method of cardioplegia, and the technique of fixation. © 1993 Wiley‐Liss, Inc.
Parenchymal cell proliferation and mechanisms for maintenance of granular duct and acinar cell populations in adult male mouse submandibular gland
Authors: Denny Paul C. , Chai Yang , Klauser Donna K. , Denny Patricia A.
Published: February 2005

To evaluate proliferation as a factor in maintenance of parenchymal cell populations in adult male mouse submandibular glands, a variety of surveys were conducted following a pulse with 3H‐thymidine. Striated granular duct (SGD) cells had the highest labeling index, followed by intercalated duct (ID) cells, then acinar (AC) cells, and granular duct (GD) cells had the lowest. These cell types showed from 30% to 60% completion of mitosis by 24 hr, with SGD, AC, and GD showing a likely second wave of mitosis sometime between 2 and 7 days after the pulse. About 40% of the pulse‐labeled cells still remained as single cells at 42 days after the pulse. Repeat divisions in daughter cells of the primary labeled cells were very rare. A shift in the pattern of labeled cells at the ID‐GD junction indicates that ID and SGD cells in this compartment are differentiating to GD cells. Further comparison of the magnitude of this conversion with the amount of noncompartmental GD cell proliferation provided a basis for calculating that ∼70% of GD cell population maintenance occurs by selfproliferation, and the remaining 30% is contributed by differentiation from ID and SGD cells. A similar survey at the ID‐acinus junction showed no evidence of conversion of ID cells to AC cells indicating that most, if not all, proliferative activity leading to AC cell population maintenance occurs by self‐proliferation. Finally, based in part on structural changes at the ID‐GD junction during the survey period, a pattern of cell conversion described as “in situ differentiation” is proposed. When this pattern is carried to fruition, this explains several structural features of the secretory complex typical to the male pattern submandibular gland. The proposed mechanism is supported by a three‐dimensionally reconstructed sequence of likely intermediate structures. © 1993 Wiley‐Liss, Inc.
Establishment of heterogeneity among blood vessels: Hormone‐influenced appearance of hepatic lipase in specific subsets of the ovarian microvasculature
Authors: Hixenbaugh Elizabeth A. , Strauss Jerome F. , Paavola Laurie G.
Published: February 2005

We used biochemical and structural approaches to analyze the influence of gonadotropic hormones on the association of hepatic lipase with specific subsets of ovarian blood vessels. Western blotting was used to detect this enzyme in effluent collected from heparin‐perfused ovaries of nonhormone‐treated immature rats and those primed with pregnant mare's serum gonadotropin (PMSG) alone or in combination with human chorionic gonadotropin (hCG). The effects of these hormones on hepatic lipase distribution among oyarian blood vessels was assessed before and after hCG and/or PMSG treatment by immunofluorescence and immunogold cytochemistry. For the latter, immunoreagents and fixative were delivered directly to chilled, unfixed ovaries by in situ vascular perfusion. Data from biochemical and structural analyses indicated that hepatic lipase was absent from nonhormone‐treated ovaries. As shown by Western blotting of ovarian effluent, the enzyme appeared following treatment with PMSG and PMSG‐hCG; it increased in amount in a time‐dependent manner, with a transient decline in the early hours after hCG injection. Enzyme levels paralleled growth and vascularization of follicles and corpora lutea; the fall tended to coincide with early events in luteal angiogenesis. Immunogold microscopy showed that hepatic lipase was abundant in thin‐walled blood vessels of theca interna of follicles, corpora lutea, and interstitial cells but sparse in those of the stroma. Moreover, during neovascularization of differentiating corpora lutea, vascular sprouts arising from hepatic lipase‐laden thecal vessels appeared to lose, then regain, the enzyme as development progressed. Our findings thus suggest (1) that hormones influence the establishment of endothelial cell heterogeneity within the microvasculature of a single organ and (2) that development of novel endothelial cell properties in specific subsets of blood vessels underlies compartmentalization of function within a tissue. © 1993 Wiley‐Liss, Inc.
Stage‐Dependent changes in spermatogenesis and sertoli cells in relation to the onset of spermatogenic failure following withdrawal of testosterone
Authors: Kerr J. B. , Millar M. , Maddocks S. , Sharpe R. M.
Published: February 2005

Rapid and complete withdrawal of intratesticular testosterone was achieved via the destruction of all Leydig cells with the specific Leydig cell cytotoxin ethane dimethanesulphonate (EDS). Restoration of testosterone levels was accomplished by administration of a single dose (25 mg) of testosterone esters (T) known to reverse the antispermatogenic effects of androgen withdrawal. Quantitation of the degenerating germ cells in cross sections of seminiferous tubules (ST) at stages IV–V, VII, IX, and X–XI of the spermatogenic cycle was used as a sensitive biological index of the effects of testosterone withdrawal and restoration upon the function of the Sertoli cells. Compared to control testicular tissues, the mean numbers of pyknotic germ cells per ST cross section at stages VII, IX and X–XI increased significantly (P < 0.01–0.001) between 4 to 8 days post‐EDS treatment, but only in stage VII tubules was this trend reversed significantly (P < 0.005) within 2 days by T supplementation. In EDS‐treated rats, stages VII, VIII, IX, and X‐XI also exhibited significant (P < 0.05–0.001) increases (compared to controls) in the volumetric proportions by which intraepithelial vacuoles appeared within the seminiferous tubules. Again, in EDS+T supplemented rats, the appearance of vacuoles was significantly (P < 0.001) suppressed in stage VII and VIII. In contrast to tubules at stages VII‐XI, those at stages IV–V were completely unaffected by testosterone withdrawal or replacement. The results show that at selected time intervals after EDS treatment, testosterone supplementation is capable of preventing/reversing these morphological changes within 2 days in stage VII tubules. It is suggested that the induction and subsequent prevention of seminiferous epithelial damage will serve as an important in vivo and in vitro approach for studies on the androgen‐mediated changes in Sertoli cell biology during phases of impairment and recovery of their function. Manipulation of adult Sertoli cell function as provided by our model should permit identification of androgen‐regulated gene products together with an understanding of their role(s) in normal and abnormal spermatogenesis. © 1993 Wiley‐Liss, Inc.
An overview of culture and isolation methods suitable for in vitro studies on pulmonary neuroendocrine cells
Authors: Speirs Valerie , Cutz Ernest
Published: February 2005

Successful isolation and culture of pulmonary neuroendocrine cells (PNEC) is essential for the investigation of cellular and membrane properties of these cells. Such studies are important to define the functional role for PNEC but are hampered by their scant numbers and widespread distribution within the pulmonary epithelium. Several in vitro methods for the isolation and culture of these cells have been described over the past decade, including organ culture, isolation of single cell suspensions enriched for PNEC, and immunomagnetic cell separation techniques. This paper reviews the various methods and discusses their advantages and pitfalls. © 1993 Wiley‐Liss, Inc.