bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of apical tubules in endocytosis in nonciliated cells of the ductuli efferentes of the rat: A kinetic analysis
Authors: Hermo Louis , Spier Nigel , Nadler Norman J.
Published: February 2005

The apical region of nonciliated cells of the ductuli efferentes of the rat contains tubular coated pits (TCP) connected to the apical plasma membrane, apical tubules (AT) which occasionally show a partial coat, and endosomes which are often continuous with one or more apical tubules. To investigate the formation and fate of TCP and AT, a quantitative analysis was performed on the labeling indices of these structures at various time intervals (0.5–120 min) after a single injection of a tracer, cationic ferritin (CF), into the lumen of the rete testis. The labeling indices of both TCP and AT exhibited similar cyclical patterns, first reaching a peak at 25 min, then dropping to a minimum at 35 min, then rising to a second peak at 60 min. Since TCP were well labeled at 30 sec while AT were not, the tracer must rapidly enter TCP and thence AT. However, since tracer was virtually absent from the lumen by 30 min, it was not possible to reconcile the second peak of labeling index of TCP and AT by this mechanism. In another experiment, rats were injected once as before, injected again at 30 min, and then sacrificed at 30 min following the second injection. The results from this experiment showed that the labeling index of TCP and AT did not drop but was similar to that of the 60‐min peak after a single injection. The interpretation is that there was recycling of tracer, which had already migrated from TCP to AT to endosomes, back to the apical plasma membrane via apical tubules. Moreover, when rats were injected once, injected again at 30 min, and sacrificed 3 min following the second injection, the labeling index for TCP and AT was significantly higher (P < .05) than at the 30‐min time interval after a single injection, indicating that recycled apical tubules were functionally capable of binding further CF. Morphological observations on images of transition between TCP and AT and the fact that AT were often found connected to endosomes suggest that TCP detach from the cell surface to give rise to AT, which in turn fuse to form endosomes. The kinetic analysis demonstrates in quantitative terms that a portion of the AT, which fuses to form endosomes, recycles back to the apical plasma membrane and contributes to the formation of new TCP.
Identification of noradrenergic nerve terminals immunoreactive for neuropeptide Y and vasoactive intestinal peptide in the rat kidney
Authors: Knight D. S. , Fabre R. D. , Beal J. A.
Published: February 2005

Cryostat‐and vibratome‐cut sections of rat kidneys were singly or doubly labeled to visualize immunoreactive tyrosine hydroxylase (THI), dopamine beta‐hydroxylase (DBHI), vasoactive intestinal peptide (VIPI), and neuropeptide Y (NPYI). Rats were perfusion fixed with 2‐4% paraformaldehyde with or without 0.15% picric acid and rinsed in buffer for 18‐48 hr. Single antigens were labeled with horseradish per‐oxidase in vibratome sections, whereas cryostat sections were used to label one antigen with perox‐idase and another with a fluorophore in the same tissue section. A dense plexus of DBHI noradren‐ergic nerves innervates the renal arterial tree, and such nerves innervate the interlobar veins and renal calyx as well. Immunoreactive NPY is colocal‐ized in most of these nerves, but some intrarenal noradrenergic nerves do not contain NPY but do contain VIP immunoreactivity. The distribution of NPYI nerves resembles that of DBHI nerves, whereas most perivascular noradrenergic nerves immunoreactive for VIP innervate selected arcuate and interlobular arteries. A small population of nonadrenergic, VIPI nerves innervates the renal calyx.
Mitochondrial structure revealed by high‐resolution scanning electron microscopy
Authors: Lea Peter J. , Hollenberg Martin J.
Published: February 2005

Mitochondrial structure has been examined in three dimensions using high‐resolution scanning electron microscopy in cells from rat liver, retina (photoreceptors and retinal pigment epithelium), and kidney (proximal convoluted tubular cells and podocytes). Tissues were prepared by aldehyde‐osmium fixation and freeze cleavage using a cryoprotectant, followed by removal of the cytosol by immersion in a dilute osmium tetroxide solution. The microscope used (Hitachi S‐570) was equipped with a secondary electron detector located in the column above the specimen, situated within the objective lens. Mitochondria in all tissues examined were found to have only tubular cristae, which in some instances could be seen to span the entire diameter of the organelle. The walls of the tubular cristae, when unfractured, were in contact with the inner mito‐chondrial membrane; and their lumens were open to the intermembranous space. We hypothesize that in cells of many, perhaps most tissues, mito‐chondrial cristae are not shelf‐like but are, in fact, tubes which span the mitochondrial matrix and are continuous with the inner mitochondrial membrane at both ends.
Human gallbladder mucosa infrastructure: Evidence of intraepithelial nerve structures
Authors: Gilloteaux Jacques , Pomerants Boris , Kelly Thomas R.
Published: February 2005

The zinc iodide‐osmium tetroxide (ZIO) fixative‐staining method was used along with topographical ultrastructure to investigate cholecystectomized human gallbladders under light and electron microscopic techniques. This method delineated neuronal structures which may be involved in controlling the functions of the gallbladder epithelium. Three epithelial cell types were described in the surface epithelium: (1) Co lumnar clear cells; (2) dark, tuft osmiophilic cells; and (3) basal clear cells with electron‐dense granules and showing intense ZIOphilic staining properties. While mucous granules were delineated in the first two cell types, the columnar epithelial clear cells are of uncertain function(s) and content but are probably absorptive cells. The small basal clear cells displaying intense ZIOphilia are associated with intraepithelial nerve endings. These nerve structures may have a sensory and/or motor function(s); they were detected throughout the gallbladder epithelial lining and mucosa.
Implantation, development of the fetal membranes, and placentation in the captive black mastiff bat, Molossus ater
Authors: Rasweiler John J.
Published: February 2005

Uterine events during pregnancy were examined histologically in laboratorybred black mastiff bats (Molossus ater) as part of an effort to develop this species as a model for studies of the factors controlling trophoblastic growth.

Embryos entered the uterus at the morula stage and in most cases shed their zonae pellucidae reasonably intact, apparently as blastocyst expansion occurred. Implantation was superficial and observed to occur only in the right uterine horn. During implantation the trophoblast was brought into apposition to the endometrium by both blastocyst expansion and closure of the uterine lumen. A decidual reaction was evident at an early stage of uterine epithelial displacement and spread rapidly through the endometrium. Initial trophoblastic proliferation occurred along the uterine lumen and into the glands, while its invasion of the endometrial stroma was delayed.

Although one or several primordial cavities have been observed to develop within the epiblast during implantation, these subsequently opened to a trophoepiblastic cavity, and the definitive amnion was formed by folding.

A choriovitelline placenta was present briefly at the somite stage, but disappeared as the exocoelom enlarged and the yolk sac collapsed. The latter persisted through pregnancy, however, as a glandular‐appearing body. As the yolk sac retracted from the chorion, it was replaced by allantoic mesoderm, creating a diffuse labyrinthine endotheliodichorial placenta. This was prominent during mid‐gestation, but was supplanted by the discoidal hemochorial placenta as the major site of feto‐maternal exchange during late pregnancy.
Variations in immunoreactivity of angiotensinogen and cathepsins B and H in rat hepatocytes over 24 hours
Authors: Waguri Satoshi , Watanabe Tsuyoshi , Kominami Eiki , Uchiyama Yasuo
Published: February 2005

To examine variations in immunoreactivity of angiotensinogen and cathepsins B and H in hepatocytes over 24 hr, rat liver was examined immunohistochemically. Immunoreactivity of angiotensinogen and cathepsins B and H in periportal and perivenous hepatocytes varied significantly over 24 hr, when analyzed by an image analyzer. In periportal and perivenous hepatocytes, immunoreactivity of angiotensinogen was highest at 0800 hr and lowest at 2000 hr or 0000 hr, whereas that of cathepsins B and H was maximal at 1600 hr and minimal at 0400 hr or 0800 hr. Proteolytic activities of cathepsins B and H in liver extracts varied in parallel to the variations in immunoreactivity of these enzymes. Localization of angiotensinogen in the liver acinus was inversely correlated to that of cathepsins B and H; angiotensinogen was predominantly localized in periportal hepatocytes, but cathepsins B and H were in perivenous hepatocytes at each time point examined. These results suggest that angiotensinogen in hepatocytes is actively synthesized and secreted early in the light period, whereas proteolytic activities in lysosomes of hepatocytes are augmented late in the light period.
Effect of indomethacin and prostaglandin E2 on structural differentiation of rat endometrium during artificially induced decidualization
Authors: Keys J. L. , Kennedy T. G.
Published: February 2005

Morphological differentiation of uterine stromal and luminal epithelial cells was studied in steroid‐injected ovariectomized rats following unilateral intrauterine instillation of sesame oil, phosphate‐buffered saline containing gelatin (PBSG), PBSG + indomethacin (IM; an inhibitor of prostaglandin synthesis), or PBSG + IM + prostaglandin E2 (PGE2). The latter two treatments were preceded by a subcutaneous injection of IM. Uteri were examined by light and electron microscopy at intervals between 8 and 120 hr (n = 4/treatment/time). Differentiation began in the periluminal antimesometrial region and progressed peripherally and towards the mesometrial aspect in all groups. Structural features and timing of differentiation were similar for oil‐injected and PBSG‐infused uteri. Administration of IM inhibited the onset of the decidual cell reaction and had deleterious effects on the luminal epithelium. Inclusion of PGE2 in the instillate accelerated stromal cell differentiation and overcame the inhibitory effects of IM. The results implicate prostaglandins, particularly PGE2, in endometrial transformation during decidualization.
N‐cadherin transcripts in Xenopus laevis from early tailbud to tadpole
Authors: Simonneau Lionel , Broders Florence , Thiery Jean‐Paul
Published: February 2005

Cadherins are Ca++ ‐dependent cell adhesion molecules which play a key role in morphogenesis and histogenesis. Two mRNAs clones (8 and 9) corresponding to two N‐cadherin pseudo‐allelic genes are present in Xenopus laevis. We report here that these transcripts share a highly homologous coding region but diverge in the non‐coding region. We have determined the pattern of N‐cadherin expression at the mRNA level by in situ hybridization with a riboprobe complementary to the EC5 domain of Xenopus N‐cadherin clone 8. This part of the sequence is the least conserved in the cadherin gene family, minimizing the risk of cross‐hybridization to other cadherins. N‐cadherin transcripts are not detectable in the first stages of development. Expression first appears in the neural plate and reaches its maximum level in the CNS at tailbud stage. From early tadpole, it diminishes, so that a very weak signal is detected in the premetamorphic frog brain. N‐cadherin expression is not uniform within the CNS, with some areas such as the roof of the rhombencephalon and the olfactory bulbs expressing higher levels of the transcripts. N‐cadherin is present in several mesodermal derivatives such as the notochord, the pronephros, and the heart. It is, however, virtually absent from the myotomes and appears in skeletal muscles at later stages of differentiation. All placodes express high levels of N‐cadherin. The non‐neural ectoderm and the endoderm are always negative. In the brain and the heart, high levels of hybridization are observed with probes corresponding to both copies of the N‐cadherin pseudo‐allelic genes in their 5′ non‐coding region, indicating that both alleles are transcribed. © 1992 Wiley‐Liss, Inc.
Optic chiasm and infundibular decussation sites in the developing rat diencephalon are defined by Glial Raphes expressing p35 (Lipocortin 1, Annexin I)
Authors: McKanna James A.
Published: February 2005

p35, a Ca++‐phospholipid‐binding protein that serves as a substrate for the EGF receptor tyrosine kinase, is expressed by primitive glial ependymal cells to define a raphe occupying the ventral midline in the spinal cord and hindbrain of rat embryos (McKanna and Cohen, Science 243:1477–1479, 1989). p35 appears transiently in the median one‐third (80 μ) of the floor plate at precisely the time and place where axons cross to form the ventral commissure. We postulated that if p35 is involved with commissure development, homologous p35 raphes might be found at decussation sites rostral to the floor plate, including the optic chiasm. The present report describes two developmentally regulated p35 raphes in the diencephalon. One raphe is present for 2–3 days at the rostral lip of the nascent infundibulum, the reported decussation site of axons running from the supraoptic nucleus to the neurohypophysis; the other raphe appears in the rostral two‐thirds of the optic chiasm, the site traversed by the optic axons. p35 is never expressed in the caudal one‐third of the chiasm that accommodates non‐retinal axons. To the best of our knowledge, this is the first identification of a specific marker for the retinal component of the optic chiasm. Because the p35 is gone by embryonic day 18.5, it is absent during final stages of chiasm formation when axons from the temporal retina decussate. Thus, p35 also may contribute to the “barrier” perceived by fibers that remain ipsilateral. Our data suggest that the p35 raphe contributes to the midline's role in commisure morphogenesis. Putative lipocortin activities including regulating PLA2, eicosanoids, or intracellular Ca++ could be involved in altering cue specificity as decussating axon growth cones traverse the p35 compartment. © 1992 Wiley‐Liss, Inc.
Chicken tibial dyschondroplasia: A limb mutant with two growth plates and possible defects of collagen crosslinking
Authors: Chen Qian , Gibney Eileen P. , Leach Roland M. , Linsenmayer Thomas F.
Published: February 2005

In the cartilaginous epiphyseal growth plate, extracellular matrix molecules such as collagens are believed to play important roles during both normal and abnormal development. One defect of the epiphyseal plate occurs in chickens with a condition termed tibial dyschondroplasia (TD). This abnormality occurs in certain strains of juvenile chickens and other rapidly developing animals. It is characterized by the presence of a mass of avascular, uncalcified cartilage which is retained in the proximal metaphysis of the tibiotarsus. To elucidate the developmental events which may be involved in this lesion, we have performed both immunohistochemistry and in situ hybridizations for collagen types II and X, known components of the extracellular matrix of the growth plate. By immunohistochemical analyses, the TD lesion contains both of these collagen types; therefore, the presence of these molecules per se is not sufficient for calcification of vascularization to occur. Since type X collagen is expressed exclusively in hypertrophic cartilage, the chondrocytes in the lesion must have undergone hypertrophy before their developmental arrest. The matrix of the lesion also reacted with a monoclonal antibody which is directed against an epitope in the NH2‐terminal telopeptide of the α1(II) chain. Our previous data suggest that this epitope is rendered unavailable in type II collagen which has undergone crosslink formation; its availability in the lesion suggests that crosslinking may be abnormal. Lastly, analyses by in situ hybridization failed to detect mRNA for either type II or type X collagen within the lesion, but chondrocytes distal to the lesion do contain mRNAs for these collagens in a spatial pattern suggesting the presence of a second growth plate. © 1993 wiley‐Liss, Inc.
Molecular markers of differentiation in Caenorhabditis elegans obtained by promoter trapping
Authors: Young Jane M. , Hope Ian A.
Published: February 2005

Differentiation of specific cell types during animal development can be detected by monitoring expression of appropriate genes. For this study, six different β‐galactosidase expression patterns which can be used as differentiation markers in the nematode Caenorhabditis elegans are described. An earlier promoter trap screen identified pools of recombinant plasmids which gave patterns of β‐galactosidase expression when used to transform C. elegans. Each recombinant plasmid contained a random fragment of C. elegans genomic DNA fused upstream of a promoterless lacZ gene. Six of these pools were chosen, and individual pattern‐producing plasmids within these pools were identified. The expression patterns have been characterized more thoroughly than in the original screen, thereby providing molecular markers for differentiation of several cell types. Many of the expression patterns involve more than one cell type. The genomic origin of the inserts of active plasmids were determined through localization on the physical genome map. © 1993 wiley‐Liss, Inc.
Localisation of transforming growth factor beta 1 in developing muscles: Implications for connective tissue and fiber type pattern formation
Authors: McLennan Ian S.
Published: February 2005

Skeletal muscles are highly ordered mixtures of cell types, with each muscle having its own characteristic pattern of fiber types, connective tissues, and vasculature. The precursors of the myogenic and connective elements of a muscle are initially intermixed and are proliferating and differentiating together in a manner that generates an ordered array of mature cells. The molecular basis of myogenesis is unknown, although in vitro studies have revealed numerous putative regulators. The results obtained from in vitro studies are not easily related to in vivo myogenesis because of a lack of information about the localisation of the putative regulators in developing muscles. The objective of this paper was therefore to describe the spatial and temporal distribution of transforming growth factor beta 1 (TGF‐β1), a small peptide that affects cultured fibroblasts, myoblasts, and vascular endothelial cells. TGF‐β1‐immunoreactivity was associated with the epimysia, perimysia, and vasculature of the developing muscles. The expression of TGF‐β1 within developing muscles had a distinct spatial and temporal pattern that correlated with the fate of adjacent myotubes. Myotubes which formed prior to the expression of TGF‐β1 developed into slow fibers whereas those which formed adjacent to TGF‐β1‐containing connective tissue matured into fast fibers. The possibility that TGF‐β1 is involved in the generation of the pattern of epi‐ and perimysia and/or fiber types is discussed. © 1993 Wiley‐Liss, Inc.
Second messenger regulation of occlusion of the spinal neurocoel in the chick embryo
Authors: Desmond Mary E. , Duzy Michael J. , Federici Benigno D.
Published: February 2005

We know that, once rostral neurulation is completed in the neuroaxis of the chick embryo, the caudal neurocoel becomes occluded and the brain rapidly expands. However, very little is known about the mechanisms maintaining occlusion. Studies had shown that occluded neurocoels reopened in embryos treated with chelators of cations, but the reasons remained unclear and the cations unidentified. To begin defining the role of cations, this study explored the effect of Ca2+, calmodulin, and cAMP on maintaining the occluded neurocoel. Chick embryos during the natural phase of neurocoel occlusion (stage 12) were cultured in vitro with drugs known to modulate Ca2+ transport, to inhibit calmodulin activity, or to elevate cAMP levels. To test if occlusion is a Ca2+ ‐dependent process, embryos were treated with verapamil and ionophore A23187. To test if occlusion requires calmodulin, embryos were treated with antipsychotic agents. To test if occlusion is cAMP dependent, embryos were treated with methylisobutylxanthine (MIX), forskolin (FOR), or dibutyl cyclic adenosine (DbC). Following each treatment, occlusion of the neurocoel was tested by injecting dye into the midbrain. All treatments resulted in a predominant number of precocious reopenings of the occluded neurocoels. MIX‐treated, naked neural tubes had a fourfold increase in cAMP, whereas FOR‐ and DbC‐treated neural tubes showed ten‐ and 14‐fold increases, respectively. The presence of calmodulin in the cells of the neural tube was confirmed by fluorescent tagging and 3H‐chlorpromazine labelling. The combined results of this study show that occlusion of the spinal neurocoel depends on exogenous Ca2+, requires calmodulin, and is cAMP sensitive. © 1993 Wiley‐Liss, Inc.
Raphe of the posterior neural tube in the chick embryo: Its closure and reopening as studied in living embryos with a high definition light microscope
Authors: van Straaten H. W. M. , Jaskoll T. , Rousseau A. M. J. , Terwindt‐Rouwenhorst E. A. W. , Greenberg G. , Shankar K. , Melnick M.
Published: February 2005

Chick embryos cultured on a curved substratum show a transient enlargement of the posterior neuropore (PN), mimicking the temporary delay of PN closure as seen in the curly tail (ct) mouse mutant (van Straaten et al. [1993] Development 117:1163–1172). In the present study the PN enlargement in the chick embryo was investigated further with a high definition light microscope (HDmic), allowing high resolution viewing of living embryos in vitro. The temporary PN enlargement appeared due to considerable reopening of the raphe of the posterior neural tube, which was followed by reclosure after several hours. The raphe was subsequently studied in detail. It appeared very irregular, with small zones of apposed, open and fused neural folds. During closure, these raphe features shifted posteriorly. A distinct fusion sequence between surface epithelium and neuroepithelium was not seen. During experimental reopeining of the raphe in vitro, small bridges temporarily arose, broke and disapeared quickly; they likely represented the first adhesion sites between the neural folds. More prominent adhesion sites partly detached, resulting in bridging filopodia‐like connections; they probably represented the first anteroposterior locations of neural fold fusion. Our observations in the living chick embryo in vitro thus show that the caudal neural tube has an irregular raphe with few adhesion sites, which can be readily reopened. As a result of the irregularity, the PN does not close zipper‐like, but button‐like by forming multiple closure sites. © 1993 Wiley‐Liss, Inc.
Retinoic acid induced heparin‐binding protein expression and localization during gastrulation, neurulation, and organogenesis
Authors: Cockshutt Amanda M. , Jonet Laurent , Jeanny Jean‐Claude , Vigny Marc , Raulais Daniel
Published: February 2005

Retinoic acid induced heparin‐binding protein (RIHB) is a highly basic, soluble polypeptide of the chick embryonic extracellular matrix. We have examined the expression and localization of RIHB during very early embryogenesis by in situ hybridization and immunohistochemistry. RIHB mRNA is very weakly detectable above background in the blastodiscs of unincubated eggs. The expression increases greatly over the first 24 hours of incubation, and is observed throughout the blastodisc in all three of the germ layers following gastrulation. As neurulation occurs, the expression becomes more restricted to certain areas, notably the ectoderm, the neural folds, and especially the notochord. After the neural tube has formed the expression in the tube itself decreases dramatically, whereas the expression in the head ectoderm and the notochord persists. After 72 hours of incubation expression remains relatively high throughout most of the embryo, with higher levels of expression in regions undergoing organogenesis and lower levels in organs which have already differentiated. RIHB protein is also weakly detectable in unincubated eggs as patches of immunoreactive material between the blastodisc and the vitelline. After 6 hours of incubation small regions of basement membrane are immunoreactive. RIHB is detected in this matrix, apparently before even fibronectin. The amount of RIHB protein increases dramatically over the first 24 hours of incubation. It is found in basement membrane separating the epiblast from the hypoblast, then later in that separating the ectoderm from the mesoderm. It is also detected surrounding individual cells, especially of the ectodermal layer. During neurulation RIHB is observed in the basement membrane surrounding the neural fold and the notochord, and in the lamina separating the ectodermal, mesodermal, and endodermal layers. Later in development, RIHB is detected in the basement membrane under the epidermis, throughout the developing limbs, and in the lamina of various developing organs, such as the eye, the pulmonary bud, the intestine, and the mesonephros. These results demonstrate that RIHB is highly expressed during the early embryonic period, by all three germ layers, and is an important and very early component of the embryonic extracellular matrix. Its very broad expression and localization argue for a more general role in development than its demonstrated weak neurotrophic activity. © 1994 Wiley‐Liss, Inc.
The arterial supply and venous drainage of the bones of the human knee joint
Authors: Crock Henry V.
Published: February 2005

This paper is based on a study of bones from fifty‐five (55) knee joints, ages ranging from newborn to ninety (90) years. Full details of techniques of specimen injection and preparation are given.

The gross arterial and venous patterns in adult bones are identical with the patterns present within these structures which are largely cartilaginous at birth.

The lower end of the femur is penetrated by radiate epiphyseal arteries around its circumference. These terminate in sinusoidal capillaries within the cartilage, the corresponding veins leaving along the lines of entry of the radiate arteries. No anastomoses exist between adjacent intracartilaginous vessels, their distribution in the epiphysis being segmental. The lateral superior genicular radiate epiphyseal arteries, for example, supply a relatively fixed segment of the lateral femoral condyle. This arrangement no longer exists when the ossific center extends to involve the sinusoidal tips of more and more vessels, effective anastomoses eventually developing between all vessels supplying the lower end of the femur.

Analagous findings are reported in the tibia.

The patella is penetrated at its center and lower pole by nutrient arteries.

In adult bones a subarticular collecting vein system is orientated parallel to articular surfaces. Short venous stems of subchondral capillary loops drain into these subarticular collecting veins which then drain off at articular margins into tributaries of the main veins. These are original findings.
Effects of testosterone on histochemical reactions of epithelium of hamster ductus epididymidis and seminal vesicle
Authors: Gohary M. El , Cavazos L. F. , Manning J. P.
Published: February 2005

Histochemical changes in hamster epididymides and seminal vesicles were studied in non‐treated controls; non‐treated castrates allowed to live for 2, 5, 10 and 20 days after gonadectomy; castrates injected daily with graded doses of testosterone propionate for 20 days (0, 50, 100, 150, 300 and 400 μg); and castrates receiving 150 μg testosterone propionate for 2, 5, 10 and 20 days. Histochemical procedures included the periodic acid‐Schiff method, toluidine blue, Sudan black B and oil red O techniques and a phospholipid procedure. In addition, statistical methods were used to evaluate seminal vesicle response.

The histochemistry of the hamster epididymis and seminal vesicle is similar to that described for the rat, mouse and rabbit. The rapid regression of the epididymal epithelium is also comparable to that reported in the rat. In contrast, the major alteration in the seminal vesicle following castration is associated with loss of secretion and not epithelial involution. Increased cellular pigmentation in the gonadectomized hamster seminal vesicle rather than cellular atrophy may be a more accurate index of the level of circulating androgen.
The brachiocephalic artery in the dog with special reference to the arterial supply of the esophagus
Authors: Jarvis J. F. , Nell Annette M. H.
Published: February 2005

Two direct branches of the brachiocephalic artery are frequently present in the dog. These are described in 33 dogs and their incidence recorded. One supplies the lower cervical trachea and esophagus and the other the thymus gland and sometimes the pericardium. Suggested names are “Tracheoesophageal” and “Thymopericardial” branches of the brachiocephalic. The embryology of the blood vessels of the esophagus is discussed and the identification of the tracheoesophageal with a secondary anastomotic vessel is considered most likely. Occasional branches from the brachiocephalic artery in man are reviewed. The Arteria Thyroidea Ima seems to bear the closest relationship to this vessel described in the dog. The value of this study in relation to heart‐lung preparations and to experimental surgery of the esophagus is suggested.
The uterotubal junction and the luminal fluid of the uterine tube in the rabbit
Authors: Hafez E. S. E.
Published: February 2005

Immature, pregnant and post partum rabbits were used to study the mechanical function of the uterotubal junction in the accumulation of the luminal fluid in the ligated uterine tube. Does were laparotomized at 10 hours, 2, 3, 4, 5, 7, 9, 16 and 29 days post coitum. One uterine tube was ligated at the fimbriae and the uterotubal junction. The other tube was ligated at the fimbriae only. The animals were autopsied at 12, 24, 36 or 48 hours after ligation and the luminal fluid in the tubes was aspirated by a microsyringe and measured volumetrically. The rate of accumulation of luminal fluid was highest in the first 24 hours and declined thereafter. When both ends of the tube were ligated, the volume of accumulated fluid within 24 hours varied from 0.71 to 1.37 ml. Maximum output of fluid occurred one to three days after copulation. There was no characteristic change in the fluid volume throughout pregnancy. When the uterotubal junction was not ligated, the luminal fluid accumulated in all stages of pregnancy except at three and four days post coitum, then at the time at parturition. The first period coincided with the time when the embryos are transported through the uterotubal junction. Shortly before and shortly after parturition the uterotubal junction relaxed, presumably because of the hormonal environment. This is evidence that a reversal in the flow direction of the luminal fluid may take place during pregnancy. The ligature of the fimbriae had no harmful effect on the cleavage rate of embryos or rate of transport through the uterotubal junction. In the immature animal, the output of luminal fluid was less than the adult and the uterotubal junction is relatively relaxed.
Influence of the hair growth cycle on the glyceride content of whole mouse skin
Authors: Goertemiller Clarence C.
Published: February 2005

In order to examine the glyceride content of whole mouse skin during the hair growth cycle, adult male C57 Black mice (C57BL/6J) were plucked of hair in a region of the mid‐dorsum in order to initiate synchronous growth of new hair. Samples of whole skin were removed from each of three different mice on various days following plucking. Stages of the hair growth cycle were ascertained by examining microscopically a portion of each sample. The remaining piece of each sample, weighing approximately 225 mg, was minced, frozen with dry ice and weighed. Following this, each sample was ground in sand with a mortar and pestle and then extracted with ethanol‐ether, cleared by centrifugation and assayed for esterified fatty acids.

This investigator found that during anagen the glyceride content of samples of whole mouse skin is nearly twice that found in telogen. It is possible that such cutaneous glycerides are major energy sources for the proliferation of hair, as well as for the development of the resting follile. On the other hand, the same factors which determine active hair proliferation may be responsible for glyceride accumulation under these conditions, and the two events otherwise could be unrelated.
Relationships of the common femoral artery
Authors: Sanders Richard J.
Published: February 2005

The relationships of the femoral artery to the anterior superior spine, the pubic symphysis, and the public tubercle were measured in 100 adult males. The average distance from the pubic tubercle to the femoral artery pulsation was 4.5 cm, from the symphysis pubis to the femoral artery pulsation was 7.7 cm, and the position of the femoral artery on a line between the symphysis and the anterior superior spine averaged its mid point. From a clinical point of view, the femoral artery is most easily located along the inguinal ligament at a point between two and three finger breadths from the pubic tubercle.
Bone cell formation and survival in H3‐thymidine‐labeled chicks under various conditions
Authors: Bélanger Leonard F. , Migicovsky B. B.
Published: February 2005

Dividing cells have been labeled in three week old chicks with H3‐thymidine and observed through radioautography at different time intervals and also under varied nutritional and hormonal conditions.

After two hours mostly primitive cells were labeled (Mesenchymal cells, fibroblasts, chondroblasts, hemopoietic precursors).

Labeled osteoclasts and osteoblasts were abundant after one and two days and their number decreased thereafter.

Labeled osteocytes were present at two and four days but rarely thereafter. Osteocyte maturation was delayed in rickets.

The osteoclasts showed a larger proportion of labeled nuclei in the Vitamin D treated birds as compared to the rachitic group. Otherwise the rate of appearance and disappearance of labeled nuclei in osteoclasts was constant in the three groups of chicks.

Osteoclasts during their life span, renew their nuclei by annexation of young ones as older nuclei degenerate.
Electron microscopic observations on the vascular barrier in the cortex of the thymus of the mouse
Authors: Weiss Leon
Published: February 2005

The thymus of newborn and young adult mice of the DBA strain was studied under the electron microscope after fixation in osmium tetroxide and embedding in araldite. In most of the animals several intravenous doses of Thorotrast were administered within 24 or 48 hours of thymectomy.

The fine vessels in the cortex of the thymus appear unusually competent. Their endothelium is complete, their basement membrane broad, and their wall further increased by adventitial cells and extracellular tissue. The epithelial reticular cell is the most peripheral adventitial element of these vessels. It extends slender processes which encircle the vessel and, by similar processes, surrounds individual or clusters of perivascular lymphocytes. This cell is disposed to mediate influences passing between cortical lymphocytes and the blood.

By cytoplasmic processes of the endothelium and the adventitial reticular cells a cellular pathway from the lumen to the outside of the these vessels is established. In smaller vessels, moreover, the adventitial enclosure by reticular cells is incomplete.

After intravenous injection thorium dioxide may be found in the vessel wall and, to a limited degree, in the surrounding tissue.

These vessels resemble both the fine vessels in the central nervous system where a blood‐brain barrier is present, and the terminal arterial vessels in the spleen.
The salivary glands and salivary bladder of the nine‐banded armadillo
Authors: Shackleford John M.
Published: February 2005

Histochemical studies of armadillo salivary glands reveal mucous acini as the predominant secretory unit of the submaxillary and parotid glands. The acidic carbohydrate moiety of the salivary mucin is mostly sialic acid since Vibrio cholera neuraminidase (sialidase) markedly reduces the alcian blue reaction in the acinar cells. Morphologically, the acini of the submaxillary gland resemble the long mucous tubules of carnivore zygomatic glands whereas the parotid gland corresponds more closely to the seromucous classification. In the submaxillary gland specialized afferent ducts terminate in a storage organ called the salivary bladder. Contents of the bladder consist of a highly viscous sialomucin plus varying amounts of acidophilic material which is negative to the periodic acid‐Schiff and alcian blue reactions. The bladder itself is composed of a wall made up of cuboidal epithelium, skeletal muscle and connective tissue and it is emptied by means of a single efferent duct which leads to the oral cavity. Parotid gland striated ducts are characterized by simple columnar epithelium containing considerable amounts of glycogen in the basal two‐thirds of the cells.
A modified rabbit's ear chamber high‐power high‐resolution studies in regenerated and preformed tissues
Authors: Brånemark P‐I , Lindström J.
Published: February 2005

Vital microscopic studies in capillary flow, cell structure and cell function with the aid of the ear chamber technique demands special mechanical and optical design of the chamber, if the full resolving power and ability of structure identification of the light microscope is to be utilized to the limit.

In order to fill these requirements a new type of ear chamber has been designed, based on the principle of a tissue section between cover glass and glass slide.

The metal parts are made of titanium, which is highly tolerable to the tissue and as transparent, parallel windows ordinary cover glass and glass slide have been used.

Special attention has been paid to the immobilization of the chamber in the microscope.

The exposed tissue has a long lifetime thus enabling long term studies.
The ultrastructure of capillaries and arterioles of the hamster dental pulp
Authors: Han Seong S. , Avery James K.
Published: February 2005

The ultrastructure of capillaries and arterioles of the hamster dental pulp has been studied. Pieces of the incisor pulp were fixed in 1% OsO4 buffered with 0.14 M veronal acetate, embedded in epoxy resin and studied in an electron microscope. The basic cytoplasmic organization of endothelial cells confirmed observations on blood vessels of other organs made by previous investigators. A large number of intracytoplasmic fibrils were found in many endothelial cells, and their presence was discussed in relation to earlier reports on the contractility of endothelial cells. Previous observations on the structural details of the intercellular region of the endothelium were confirmed and elaborated upon. The manner in which the cytoplasmic flaps of adjoining cells were oriented indicated that, if the integrity of the capillary wall was maintained, only cells with capacity for ameboid movement could creep through the region. Thus they were thought to play a role as an effective barrier against the passage of red blood cells. Numerous micropinocytosis and pinocytosis vesicles were found in association with plasma membranes. The significance of their structure in the transport of materials across the capillary wall is discussed. The fine structure of the pericyte resembled that of the fibroblast. Portions of plasma membranes of adjacent smooth muscle cells in the media of arterioles were brought together closely and resembled attachment zones.
Age variations in the specific surface of howship's lacunae as an index of human bone resorption
Authors: Sedlin Elias D. , Villanueva Antonio R. , Frost Harold M.
Published: February 2005

Internal remodelling of bone occurs continually during life in discrete foci throughout cortex and large trabeculae. It is defined as the process of replacement of primaryappositional bone with Haversian bone occurring within the periosteal‐endosteal envelope. The foci are produced by osteoclastic resorption of preexisting bone and are subsequently filled in by successive waves of osteoblasts that deposit new matrix. In this study, measurements of the surface area of Howship's lacunae in rib diaphysealcortex are presented for 137 relatively normal individuals of both sexes and ranging from one month to 84 years of age. Undecalcified cross‐sections were prepared fresh from rib obtained at thoracotomy or post‐mortem. Measurements were performed with a calibrated Zeiss Integrating Eyepiece II. It was found that the values for this resorption index were highest in infancy and lowest in middle and early adult life. The maximum adult values were attained in the seventh decade. No differences were noted that could be accounted for by sex. Correlation of these data with an index of secondary bone formation in this same group of bones enabled the authors to conclude that the internal remodelling rate of rib cortex is highest in infancy, lowest in the fourth decade and attains a secondary peak in the seventh decade. The authors suggest that the phasing of the changes noted are due to some as yet unknown programming of the mesenchymal cell. Since no increases coincided with growth spurts during childhood and adolescence, they conclude that the process of internal remodelling may be under a completely different mechanism of control from that governing skeletal growth and maturation.
Maintenance of normal pituitary weight and cytology in the spayed rat following estradiol implants in the arcuate nucleus
Authors: Lisk R. D.
Published: February 2005

Estradiol contained within the lumen of 30 gauge hypodermic tubing was implanted into the arcuate nucleus, mammillary bodies, or anterior lobe of the pituitary, either at the time of spaying or 11 days or 60 days after castration. The normal pituitary weightand cytological characteristics of the gonadotrophs were maintained only when estradiolwas implanted in the arcuate nucleus after spaying. Blank tubing implants in all the previously mentioned locations or estradiol implants in the mammillary bodies or anteriorpituitary were completely ineffective in inhibiting the typical sequence of castration cell formation which occurs in the pituitary of the spayed rat.
A quantitative study of human superior cervical sympathetic ganglia
Authors: Ebbesson Sven O. E.
Published: February 2005

The postganglionic neurons in four human superior cervical sympathetic ganglia and the preganglionic axons in the trunks just caudal to these ganglia were counted. The number of postganglionic neurons varied from 760,370 to 1,041,652. The estimates of the number of preganglionic fibers ranged from 5,305 to 12,008. The resulting ratio of preganglionic to postganglionic neurons was as high as 1 to 63 in one ganglion and as low as 1 to 196 in another. The number of postganglionic neurons in human superior cervical sympathetic ganglia is approximately ten times greater than the figure obtained in the cat and 20 times greater than in rabbit ganglia. The number of preganglionic axons does not vary proportionally and is of the same order of magnitude in cat, dog and man.
Abnormal pulmonary and aortic semilunar valves in embryos
Authors: Shaner Ralph F.
Published: February 2005

Four kinds of abnormal pulmonary and three kinds of abnormal semilunar valves are described from pig and human embryos of an age equivalent to the first human trimester. The pulmonary valves include bicuspid forms resulting from the absence of an anterior cusp, from the fusion of left and anterior cusps and from the fusion of left and right cusps; also dome‐shaped valves. The aortic valves include bicuspid forms resulting from the absence of the non‐coronary cusp and from the fusion of right and left cusps. All are discussed in the light of accompanying heart anomalies and a re‐examination of normal cusp development. Embryonic abnormal pulmonary valves are generally linked with early stages of Fallot's tetralogy. They are caused by an arrest in heart development and the changed hemodynamic conditions that result from it. Embryonic abnormal aortic valves are caused by an arrest in heart development and an abnormal degree of coarctation of the aorta. The evidence from embryos supports the general belief that abnormal pulmonary cusps of all ages, when not caused by infection, are of congenital origin. Some aortic abnormal valves are also of congenital origin, but are hard to distinguish from similar ones produced after birth by postnatal coarctation.
Closure of the spheno‐occipital synchondrosis
Authors: Powell Thomas V. , Brodie Allan G.
Published: February 2005

Comparative anatomical and histologic methods have been responsible for the belief that the spheno‐occipital synchondrosis in the human is an active growth center until the adult stage is reached. According to standard texts the suture closes between the eighteenth and twenty‐fifth years. The present investigation was a re‐examination of this question by means of midsagittal laminagraphy. The material consisted of 205 males 8 to 21 years; and 193 females 6 to 18 years. The midsagittal lamina of the spheno‐occipital junction appears as a band of less radiopacity when the suture is open. Closure was found to occur first on the cranial border and to progress downward. Initial closure was found in a male of 10 years, 10 months; first complete closure at 13 years, 4 months. The last found completely open was at 15 years, 2 months. Complete obliteration was found at 8 years, 1 month in one female subject and the last completely open suture at 13 years, 9 months. In general, the closing age for the males was between 13–16 years, and the female between 11–14 years.
Fine structure of splenic pulp
Authors: Galindo Benito , Freeman James A.
Published: February 2005

Splenic tissue from the dog, monkey, guinea pig, and rat were fixed in OsO4, embedded in maraglas, and examined by electron microscopy. The red pulp is composed of sinuses, the walls of which are formed by littoral cells (macrophages and fixed reticulum cells) resting on a framework of reticulum. The pulp cords (Billroth cords) are formed by sinuses containing bands of reticulum which compartmentalize the cord. Interlocked littoral cells and entrapped formed elements of the blood are found in the cords. The stroma of the white pulp is composed of two types of fixed reticular cells (fixed reticular cells, type A; and fixed reticular cells, type B), macrophages, and cell types intermediate between macrophages and fixed reticular cells. The reticulum of the white pulp is similar to that of the red pulp. With PTA staining the extracellular connective tissue (reticulum) is found to be composed of a homogeneous substance with fibrillar elements, namely (1) fibrils 50 mμ in diameter with a 640 Å axial periodicity, (2) fibrils of similar diameter without periodicity, and (3) non‐periodic, closely packed undulating, parallel fibrils ca. 70 Å in diameter. The reticulum is, in general, enclosed by cytoplasm of littoral cells or sandwiched between cells; rarely, however, the reticulum appears to be in contact with the blood in the sinus. The junction of capillary and sinus is abrupt and the terminal capillary endothelium is surrounded by litoral cells.