bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow cytometric DNA analysis of corneal epithelium
Authors: Burns E. Robert , Roberson Michael C. , Brown Michael F. , Shock John P. , Pipkin James L. , Hinson William G. , Anson Jeanne F.
Published: February 2005

We have modified an existing technique in order to perform DNA analysi by flow cytometry (FCM) of corneal epithelium from the mouse, rat, chicken, rabbit, and human. This protocol permitted an investigation of human corneal scrapings from several categories: normal, aphakic bullous keratopathy (ABK), keratoconus (KC), Fuch's dystrophy, edema, epithelial dysplasia, and lipid degeneration. No abnormal characteristic cell‐kinetic profile was detected when averaged DNA histograms were compared statsitically between the normal and either ABK, KC, edema, or Fuch's dystrophy groups. Abnormal DNA histograms were recorded for cell samples that were taken (1) from three individuals who had epithelial dysplasia and (2) from one individual diagnosed with lipid degeneration. The former condition was characterized by histograms that had a subpopulation of cells with an aneuploid amont of DNA or had higher than normal percentages of cells in the S and G2 + M phases of the cell cycle. Corneal cells from the patient who had lipid degeneration had an abnormally high percentage of cells in the G2 + M phases of the cell cycle. The availability of accurate DNA flow cytometric analysis of corneal epithelium allows further studies on this issue from both experimental and clinical situations.
Angiology of the brain of the baboon Papio ursinus, the vervet monkey Cercopithecus pygerithrus, and the bushbaby Galago senegalensis
Authors: Lake A. R. , Van Niekerk I. J. M. , Le Roux C. G. J. , Trevor‐Jones T. R. , De Wet P. D.
Published: February 2005

The investigation was undertaken to compare the blood supply and venous drainage of the brain of the baboon P. ursinus, the vervet monkey C. pygerithrus, and the bushbaby G. senegalensis with that of man, because these animals are extensively used as research models.

The blood supply of the three primates was found to be similar in each case. Like man they have a complete circulus arteriosus; but they have a single anterior cerebral artery, whereas man has paired anterior cerebral arteries. The arterial supply to the cerebellum in the primates is similar to that in man, the main difference being a “common inferior cerebellar artery” which bifurcates to form the anterior inferior cerebellar and posterior inferior cerebellar arteries. In man, these arteries arise separately from the basilar artery and vertebral arteries, respectively.

The dural venous drainage was also found to be similar in these primates but was far more extensive than in man. The primates have additional sinuses–the more important of these being the “basisphenoid sinus” and the petrosquamous sinus. The former drains the basilar sinus and is itself drained via the vertebral venous plexus and internal jugular vein. The latter drains via the petrosquamous foramen into the retromandibular vein. The petrosquamous sinus has a rostral extension which drains through the foramen ovale and two lateral and medial connecting sinuses which drain the cavernous and basilar sinuses, respectively. These sinuses are not found in man.
Anatomical studies of the coronary system in elasmobranchs: I. Coronary arteries in lamnoid sharks
Authors: De Andrés A. V. , Muñoz‐chápuli R. , Sans‐Coma V. , García‐Garrido L.
Published: February 2005

A study of the anatomy of coronary arteries has been done in five shark species of the order Lamniformes: Isurus oxyrinchus, Isurus paucus, Lamna nasus, Alopias superciliosus, and Alopias vulpinus. The study, which included 26 specimens, was carried out with the injection‐corrosion technique, obtaining internal casts of the main trunks and coronary arterial branches.

The results have shown a high degree of constancy in the coronary patterns in all species and a number of general features common to all of them, except for Alopias vulpinus. In this species, a mesh‐like ventricular pattern of intramyocardial vessels was found instead of subepicardial ventricular coronary branches with a definite patern.

It was also shown that there is a wide range of variation among the species regarding the relative importance of the dorsal and ventral coronary trunks. Thus, Isurus oxyrinchus showed a clear predominance of the ventral coronary trunk, whereas in Alopias superciliosus, most of the ventricle was supplied by branches derived from the dorsal coronary trunk.
Uterine fibronectin mRNA content and localization are modulated during implantation
Authors: Rider Virginia , Carlone Diana L. , Witrock Debra , Cai Cindy , Oliver Noelynn
Published: February 2005

Fibronectin mRNA and protein content were examined during embryonic implantation in the rat uterus. Content of total fibronectin mRNA at day 6 of pregnancy increased relative to the non‐pregnant uterus. In contrast, fibronectin protein content of the subepithelial stroma was relatively decreased except in the region directly surrounding the lumen, and this fibronectin immunoreactivity was sensitive to hyaluronidase treatment. These changes are likely to reflect the degradation and subsequent remodeling of the previously stable uterine extracellular matrix in preparation for embryonic implantation. A+,B‐,V+ fibronectin mRNAs were present in both the non‐pregnant and day 6 pregnant uterus with increased content of A+ and V+ fibronectin mRNAs in the latter. A+ fibronectin mRNA was distributed throughout the endometrial stroma of the non‐pregnant uterus and content of the subepithelial stroma increased by day 4 of pregnancy, coincident with progesterone action on the endometrium. On day 6 of pregnancy, fibronectin mRNAs encoding the V95 and A regions were preferentially localized to the mesometrial zone of the subepithelial stroma. Accumulation of these mRNA splicing variants at the mesometrial zone was dependent upon decidualization, but the embryo was not required. Thus, there are two major changes in uterine fibronectin gene expression as a result of pregnancy: increased fibronectin mRNA content and mesometrial localization. These changes suggest a key function for fibronectin in implantation and imply the operation of a regulatory program of fibronectin gene expression which depends on hormonal sensitization and a nidatory stimulus. © 1992 Wiley‐liss, Inc.
Stripe selection: An intrinsic property of some pattern‐forming models with nonlinear dynamics
Authors: Lyons Michael J. , Harrison Lionel G.
Published: February 2005

In two‐dimensional pattern formation, the genesis of striped rather than spotted patterns may involve preexisting spatial asymmetries, such as unidirectional gradients or asymmetric shape of the pattern‐forming domain. In the absence of such asymmetries, some kinds of nonlinear dynamics still lead to striped rather than spotted patterns. We have studied the latter effect both by extensive computer experiments on a range of nonlinear models and by mathematical analysis. We conclude that, when the dynamic equations are written in terms of departure from the unpatterned state, the presence of nonlinearities which are odd functions of these departures (e.g., cubic terms) together with absence of even nonlinearities (e.g., quadratic terms) ensures stripe formation. In computer experiments, we have studied the dynamics of two‐morphogen reaction‐diffusion models. The mathematical analysis presented in the Appendix shows that the same property exists in more generalized models for pattern formation in the primary visual cortex. © 1993 Wiley‐Liss, Inc.
Role of growth factors in catecholaminergic expression by neural crest cells: In vitro effects of transforming growth factor beta1
Authors: Howard Marthe J. , Gershon Michael D.
Published: February 2005

The differentiation of neural crest cells into catecholaminergic neurons is dependent upon both intrinsic properties and signals from the embryonic microenvironment. In tissue culture, the development of catecholaminergic traits is dependent upon factors present in chick embryo extract (CEE). This dependency suggests that soluble growth factors affect catecholaminergic differentiation in vivo. We have studied the role of CEE‐derived factors and the potentially related influence of characterized growth factors on catecholaminergic phenotypic expression in avian neural crest cells. In this report, we show that CEE‐derived factors and transforming growth factor beta1 (TGF‐β1) differentially influence catecholaminergic phenotypic expression as well as melanogenesis. TGF‐β1 substituted for CEE‐derived factors and supported the in vitro differentiation of tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DBH) immunoreactivities, as well as catecholamine biosynthesis and storage. Differentiation of catecholaminergic cells was dependent on factors present in 10% CEE during the first 1–4 days in culture suggesting an initial critical period for exposure. One day of initial exposure to either CEE‐derived factors or TGF‐β1 was sufficient to support the subsequent expression of catecholaminergic phenotypic characteristics. The time course of responsiveness to TGF‐β1 was different than for CEE‐derived factors. Neural crest cells remain responsive to TGF‐β1 for at least 5 days, which is past the critical period for CEE‐derived factors. Bioassay of CEE shows that endogenous levels of TGF‐β are less than or equal to 0.5 ng/ml. Immunoprecipitation of TGF‐β from CEE or blockade by neutralizing antibodies did not result in a loss of catecholaminergic differentiation by neural crest cells. Although CEE supports melanogenesis under all of the growth conditions tested, TGF‐β1 was found to be inhibitory. © 1993 wiley‐Liss, Inc.
Characterization of the Xenopus Hox 2.4 gene and identification of control elements in its intron
Authors: Bittner Dennis , De Robertis Eddy M. , Cho Ken W. Y.
Published: February 2005

We report on the Xenopus homolog of the Hox 2.4 gene. This gene occupies the next to 5′‐most position in the Xenopus Hox 2 complex. Hox 2.4 RNA is first detected at the early neurula stage, reaching a peak at the early tailbud stage, and is localized in the middle and posterior portions of the embryos Antibodies raised against a fusion protein show expression of Hox 2.4 protein in Xenopus embryos in a band located in the mid spinal cord. Thus, the protein is expressed in a narrower domain than that of Hox 2.4 mRNA. The Xenopus Hox 2.4 antibody cross‐reacts readily with mouse embryonic tissue, where the protein is detected in migrating neural crest cells, the dorsal portion of the spinal cord, somites, lateral plate mesoderm, and in the forelimb bud. The Xenopus Hox 2.4 intron shares considerable sequence identity with the intron in the mouse homolog. A reporter gene containing an element from this intron which can bind homeodomain proteins is activated following microinjection into Xenopus embryos. The short distance between the end of the Hox 2.4 cDNA and the start site of the neighboring gene in the complex raises the possibility that this transcriptional element might be shared by two Hox genes. © 1993 wiley‐Liss, Inc.
Expression of phospholamban mRNA during early avian muscle morphogenesis is distinct from that of α‐actin
Authors: Toyofuku Toshihiko , Doyle Donald D. , Zak Radovan , Kordylewski Leszek
Published: February 2005

We have studied the expression of phospholamban during the early development of chick embryos by in situ hybridization and have compared it to that of α‐cardiac and α‐skeletal actin. In adult cross‐striated muscles there is only one phospholamban gene and it is expressed exclusively in the heart and slow muscles. In the heart phospholamban transcripts were first detected at stage 14 in the region of presumptive ventricle and at stage 20 in the atrium. In the myotomal portion of the somites phospholamban mRNA was first detected at stage 20, which lagged behind the appearance of the α‐actins. In the limb rudiments all three mRNAs were barely detectable through stage 24, but increased by stage 28 +. However, quantitative analysis of signal intensity at stage 28 + indicated that less phospholamban mRNA is present in the limb bud than in the myotome since for phospholamban the ratio of the signal density in the myotome to that in the limb rudiments was about twice the value of the ratio determined for the α‐actins. Northern blot analysis of embryonic day 11 chick fast pectoralis muscle showed that phospholamban mRNA was not detected in vivo while α‐cardiac actin mRNA was. Moreover, no phospholamban mRNA was detected in primary cultures derived from pectoralis muscle of the same age. In concert with previous observations that phospholamban is not detectable at stage 30–32 in wing or thigh muscle, these results suggest that phospholamban mRNA is expressed independently of the α‐actins in the limb buds during early myogenesis. © 1993 wiley‐Liss, Inc.
Evidence for compartmental identity in the development of the rat lateral gastrocnemius muscle
Authors: Gatesy Stephen M. , English Arthur W.
Published: February 2005

In adult rats, each neuromuscular compartment of the lateral gastrocnemius muscle (LG) is exclusively innervated by a primary branch of the LG nerve. In neonates, however, a small percentage of LG cells receives inputs from more than one primary nerve branch; these inputs are known as cross‐compartmental. Cross‐compartmental inputs are normally lost from the medial compartment of LG (LGm) by the 8th postnatal day. To investigate the mechanisms involved in the elimination of cross‐compartmental inputs, muscle fibers in the LGm compartment were denervated by cutting the LGm nerve branch in 1–4 day old rat pups and in adult rats. We then assessed the degree of cross‐compartmental innervation within the “denervated” compartment using intracellular recordings from neonatal muscle fibers or immunohistochemical staining for nerve cell adhesion molecule (N‐CAM) and neurofilament protein in adult muscles. Following LGm axotomy in neonates, cross‐compartmental innervation is more extensive than in controls and is present as late as 20 days after birth. Thus, in the absence of “native” LGm axons, neonatal cross‐compartmental inputs proliferate by axonal sprouting and the formation of new synapses on vacant LGm fibers. In contrast, axotomized adults do not form new cross‐compartmental inputs over the same time period. The differential response of neonates and adults to muscle nerve branch denervation is evidence for the existence of some form of compartment‐specific recognition. We propose that compartmental identity either arises or becomes relatively more potent during ontogeny and normally acts selectively to eliminate foreign axons and deter the formation of new cross‐compartmental inputs. © 1993 wiley‐Liss, Inc.
Ablation of various regions within the avian vagal neural crest has differential effects on ganglion formation in the fore‐, mid‐ and hindgut
Authors: Peters‐Van Der Sanden Marjo J. H. , Kirby Margaret L. , Gittenberger‐De Groot Adriana , Tibboel Dick , Mulder Maarten P. , Meijers Carel
Published: February 2005

The vagal neural crest adjacent to the first seven somites gives rise to both ganglionic and ectomesenchymal derivatives. Ganglionic derivatives are the neurons and supportive cells of the enteric nervous system (ENS), cardiac, and dorsal root ganglia. Ectomesenchymal derivatives are cells in the cardiac outflow tract and the mesenchymal components of thymus and parathyroids. Ectomesenchymal derivatives are formed by a segment of the vagal neural crest, from the level of the otic vesicle down to the caudal boundary of the third somite, called the cardiac neural crest. We performed neural crest ablations to study regional differences within the avian vagal neural crest with regard to the formation of the ENS. Ablation of the entire vagal neural crest from the mid‐otic vesicle down to the seventh somite plus the nodose placode resulted in the absence of ganglia in the midgut (jejunum and ileum) and hindgut (colon). The foregut (esophagus, proventriculus, gizzard, and duodenum) was normally innervated. After ablation of the vagal neural crest adjacent to somites 3–5, ganglia were absent in the hindgut. Ablations of vagal neural crest not including this segment had no effect on the formation of the ENS. We surmise that the innervation of the hindgut in vivo depends specifically on the neural crest adjacent to somites 3–5, whereas innervation of the midgut can be accomplished by all segments within the vagal neural crest. The foregut can also be innervated by a source outside the vagal neural crest.

To study intrinsic differences between various vagal neural crest segments regarding ENS formation, we performed chorioallantoic membrane cocultures of segments of quail vagal neural anlage and E4 chicken hindgut. We found that all vagal neural crest segments were able to give rise to enteric ganglia in the hindgut. When the neural crest of somites 6 and 7 was included in the segment, we also found melanocytes in the hindgut, suggesting that this segment is more related to trunk neural crest. Furthermore, we found that the vagal neural anlage from older embryos (>18 somites) showed an increased potential to form enteric ganglia. This suggests that vagal neural crest cells that have been in prolonged contact with the neural tube in vivo, because of either late emigration or delayed migration, have an increased probability to form enteric ganglia. © 1993 wiley‐Liss, Inc.
Colonization of the bowel by neural crest‐derived cells re‐migrating from foregut backtransplanted to vagal or sacral regions of host embryos
Authors: Rothman Taube P. , Le Douarin Nicole M. , Fontaine‐pérus Josiane C. , Gershon Michael D.
Published: February 2005

The enteric nervous system (ENS) in avian embryos is formed by cells that migrate to the bowel from vagal and sacral regions of the neural crest. Experiments were carried out to evaluate the developmental potential of crest‐derived cells at the time they colonize the gut. Backtransplantation of E4 quail foregut (or control aneuronal hindgut) was used to determine whether crest‐derived cells that have previously colonized the bowel are capable of following defined neural crest migration pathways in host embryos. Vagal and sacral, but not truncal, backgrafts provided donor cells for the host's bowel. These cells were immunostained by the neural crest marker, NC‐1, restricted to the ENS, and appeared only when foregut was backgrafted; therefore, they were crest‐derived. In order for cells to migrate to the host's bowel, backgrafts evidently had to be located in the vicinity of the neuraxis at the time crest‐derived cells exited from them. When vagal grafts moved away from the neuraxis, crest‐derived donor cells colonized cephalic ganglia and the vagus nerves near the grafts; however, such cells did not migrate down the vagi to the host's gut. Sacral backgrafts provided crestderived cells for the bowel only if the donor gut was transplanted prior to the formation of somite 28, at the level of the disappearing primitive streak. Cells from vagal backgrafts were capable of reaching the host's cloaca, but backgrafts placed at a sacral level colonized only the postumbilical bowel. In addition, donor cells proliferated extensively within the host's gut. Whenever the host's gut was colonized, donor crest‐derived cells were also found in non‐enteric targets including nerves, cephalic (vagal backgrafts), or sympathetic (sacral backgrafts) ganglia; however, donor cells did not form ectomesenchyme or melanocytes. These data suggest that (i) crest‐derived cells that have colonized the bowel remain capable of remigrating and following defined neural crest migration pathways in host embryos; (ii) remigrating cells must enter these pathways at their start; (iii) the gut stimulates the proliferation of enteric crest‐derived cells; (iv) vagal crest‐derived cells can follow sacral pathways to reach enteric, Remak's, or sympathetic ganglia; and (v) the migration of crest‐derived cells within the gut is determined more by the route they follow to reach the bowel than by their level of origin in the neural crest. © 1993 wiley‐Liss, Inc.
Gene expression of CD24 core peptide molecule in developing brain and developing non‐neural tissues
Authors: Shirasawa Takuji , Akashi Takumi , Sakamoto Kyoichi , Takahashi Hiroshi , Maruyama Naoki , Hirokawa Katsuiku
Published: February 2005

CD24 is a signal transducing molecule on the surface of most human B cells, murine immature T cells, myeloid and erythroid lineage cells. We isolated rat CD24 gene from embryonic brain cDNA library and characterized the gene expression during rat embryogenesis. Rat CD24 cDNA is homologous to murine and human CD24 gene with respect to the structure of signal peptide, N‐glycosylation sites, and possible glycosyl phosphatidylinositol (GPI) linker attaching site, suggesting that rat CD24 is a transducing glycorprotein anchoring membrane via GPI linker. In the developing embryo, in situ hybridization analyses revealed that CD24 transcript was detected in primitive ectoderm, mesoderm, and ventral endoderm of day 9 postcoitum (p.c.) embryo. In central nervous systems CD24 transcript was strongly expressed in postmitotic cells of spinal cord, hindbrain, midbrain, and forebrain from day 11 p.c. embryo to day 21 p.c. embryo but was dramatically down regulated in adult brain. Furthermore, expression was also detected in epithelium during development of non‐neural tissues, such as intestinal mucosal epithelium, nasal epithelium, ductal epithelium of salivary gland, bronchial epithelium, renal tubular epithelium, and hair follicles. In tooth development, where correct epithelium requires epithelial‐mesechymal interactions, CD24 mRNA was specifically induced in mesenchymal cells differentiating into odontoblast in dental papilla, suggesting the pivotal role of CD24 molecule in cell differentiations in vivo. We suggest that CD24 gene may encode the core peptide molecule of 31 kDa GPI linked molecule which has been known to be important in the migration of neurons on astroglial processes during development. © 1993 Wiley‐Liss, Inc.
Proportion of proliferative cells in the tadpole retina is increased after embryonic lesion
Authors: Wetts Richard , Kook Ji Hae , Fraser Scott E.
Published: February 2005

Little is known about the cellular mechanisms that cause some cells to stop dividing while leaving neighboring cells free to continue dividing. Such events occur during development of the Xenopus Retina; all cells of the embryonic eyebud are mitotic, but by stage 37 (St 37), only cells at the ciliary margin continue to proliferate as neighboring cells become post‐mitotic. The mechanisms that control these different proliferative fates remain unknown. One possibility is that total cell number regulates the initial number of proliferative cells at the ciliary margin. To test this hypothesis, we reduced the cell number by surgically removing a portion of the embryonic eyebud, including part of the prospective proliferative zone. Cell counts confirmed that the numbers of both the mitotic, undifferentiated cells and the post‐mitotic, differentiated cells were reduced following the partial ablation. A regression analysis suggested that the initial number of undifferentiated cells was a fixed proportion of the total number, but that this proportion was increased by the partial ablation. This increase occurred for all stages that the partial ablation was performed, from early optic vesicle to mid optic cup stages. The proportion of undifferentiated cells was normal in sham‐operated retinas, indicating that the increase in partially ablated retinas was induced by tissue removal and not by wound healing. Analyses of clones derived from single precursors, labeled with a fluorescent lineage tracer, indicated that the rate of proliferation was the same in partially ablated and sham‐operated retinas. Measurements of bromodeoxyuridine incorporation directly confirmed that at the ciliary margin cell division time was unchanged after partial ablation. Our observations are most consistent with the hypothesis that the proportion of undifferentiated cells was increased because cells that would have become post‐mitotic remained proliferative after the partial ablation. Furthermore, cell‐cell interactions most likely play a major role in controlling the initial number of proliferative cells in the tadpole retina. © 1993 Wiley‐Liss, Inc.
Cloning and developmental expression of the chick type II and type III TGFβ receptors
Authors: Barnett Joey V. , Moustakas Aristidis , Lin Wei , Wang Xiao‐Fan , Lin Herbert Y. , Galper Jonas B. , Maas Richard L.
Published: February 2005

To address the role of peptide growth factors in chick organogenesis, we have focused on TGFβ2 and have cloned the chick Type II and Type III TGFβ receptors. The chick Type II receptor is a serine/threonine kinase with a ligand binding profile identical to the human receptor and a divergent N‐terminus when compared to the mammalian receptors. The chick Type III receptor is a betaglycan that demonstrates a binding profile identical to the rat receptor and contains a single transmembrane spanning domain and short cytoplasmic tail that are highly conserved when compared to the mammalian receptors. Both the Type II and Type III TGFβ receptors are coexpressed during chick embryogenesis in the developing heart, lung, and eye, and are developmentally upregulated in parallel in the heart and lung. Levels of both receptor proteins and mRNAs also increase in cardiocytes cultured from different developmental stages, in agreement with the increase in Type II and Type III receptor mRNA levels observed in the developing heart. Although exhibiting different temporal or spatial profiles from the receptors, TGFβ2 is also expressed in the developing heart, lung, and eye. These findings are consistent with recent data indicating that co‐expression of both the Type II and Type III TGFβ receptors is required for high affinity binding of TGFβ2 by the Type II receptor and suggest that TGFβ2 and the Type II and Type III TGFβ receptors participate in heart, lung, and eye development. © 1994 Wiley‐Liss, Inc.
Pattern regulation in the chick autopodium at advanced stages of embryonic development
Authors: Gańan Yolanda , Macias Domingo , Hurle Juan M.
Published: February 2005

In previous studies we have observed that the interdigital tissue of the chick embryo leg bud during the stages previous to interdigital cell death exhibits a considerable chondrogenic potentiality both in vivo and in vitro. In the present investigation we have carried out a variety of experimental manipulations of the chick leg bud at stage 29 to discover possible mechanisms accounting for interdigital ectopic chondrogenesis and extradigit formation. Our results show that the interdigital tissue is capable of forming an extradigit when temporarily isolated microsurgically and regrafted in its original loction and after deletion of one of the adjacent digital primordia, suggesting that developing phalangeal cartilages exercise an inhibitory effect on chondrification in adjoining tissues. Furthermore, and of greater importance, ablation of the primordium of a digit is followed by normal development of the definitive digit if the wound surfaces are suitably apposed. These results reveal a considerable regulatory potentital in the autopodium at advanced stages of development. © 1994 Wiley‐Liss, Inc.
Localization of CRABP‐I and CRABP‐II mRNA in the early mouse embryo by whole‐mount in situ hybridization: Implications for teratogenesis and neural development
Authors: Lyn Sally , Giguère Vincent
Published: February 2005

Retinoic acid (RA) has been implicated in vertebrate neural pattern formation. In this paper we analysed the expression patterns of the cellular retinoic acid binding proteins (CRABP‐I and II) during early morphogenesis in normal and RA‐treated mouse embryos by whole‐mount in situ hybridization. This technique allowed a detailed analysis of the spatial and temporal changes in mRNA expression pattern. Both CRABPs were expressed in a rhombomere specific pattern; putative neural crest cells in the branchial arches expressed the CRABPs at levels corresponding to the rhombomere from which they were derived. CRABP‐II, but not CRABP‐I, was expressed in the neural epithelium caudal to the hindbrain. CRABP‐I is strongly expressed in a fine net‐like pattern which extends from the caudal diencephalon to the rostral hindbrain and remains predominantly dorsal to the lateral midline of the neural tube. This network corresponds to the pattern formed by the putative first axons of the embryonic mouse brain which are produced by the developing neurons of the mesencephalic nucleus of the trigeminal nerve. Although the expression of CRABP‐I was unaffected by a teratogenic dose of RA, CRABP‐II expression was increased slightly with no alteration in the normal spatial or temporal boundaries. These results support the suggestion that the CRABPs may play an important role in modulating endogenous RA levels, particularly in the developing nervous system and its neural crest derivatives. Furthermore, the limited ability of CRABP mRNA levels to respond to exogenous retinoids may be a factor in retinoid teratogenicity. © 1994 Wiley‐Liss, Inc.
From gastrulation to neurulation: Transition in retinoic acid sensitivity identifies distinct stages of neural patterning in the rat
Authors: Cunningham Michael L. , Mac Auley Alasdair , Mirkes Philip E.
Published: February 2005

Early neural development is a multistep process with morphologically distinct stages; however, the molecular events that underlie morphologic development are poorly understood. Retinoic acid (RA) was chosen as a teratogen to perturb development because this endogenous molecule is thought to play an integral role in normal neuraxis formation in many vertebrate species. We have examined the effects of RA on early neural patterning in the rat at three morphologically distinct stages: late streak, foregut pocket, and early somite. In this model exogenous RA exposure during mid‐gastrulation (late streak stage) leads to severe disruption of anterior neural development as determined by morphologic and molecular (Engrailed [Eu] gene expression) markers. This disruption in anterior neural development is associated with excessive cell death in the hindbrain posterior to the En expression domain. In contrast, at the time the neural folds begin to elevate (foregut pocket stage) there is a dramatic reduction in the sensitivity of anterior neural development to exogenous RA as reflected by En expression and cell death patterns. These results suggest that we have identified a major transition in the development of the anterior neuraxis that is reflected in a transition in sensitivity to RA. This transition in sensitivity demonstrates that the fundamental patterning mechanisms that separate fore‐ and midbrain from hindbrain occurs very early in neurogenesis. © 1994 Wiley‐Liss, Inc.
The nipple and the areola of the human female breast
Authors: Giacometti Luigi , Montagna William
Published: February 2005

The nipple is covered by an epidermis with a characteristically intricate understructure of ridges. There are numerous, large sebaceous glands in the nipple, some opening inside the milk ducts. The terminal segments of the milk ducts are surrounded by bundles of smooth muscle arranged in sphincter‐like patterns. There are relatively few nerve endings in the epidermis of the nipple and areola; these are Krause‐like endings, and a number of non‐descript nerve endings are found around the epidermal ridges. All of these nerves, and those around the apocrine and eccrine sweat glands in the areola, contain acetylcholinesterase. The tubercles of Montgomery are accessory mammary glands. Though mammary glands are said to be modified apocrine sweat glands, the two have neither gross, nor histological and histochemical resemblances.
Effects of pancreatic homografts on the blood of normal and diabetic hamsters
Authors: House E. L. , Jacobs M. S. , Pansky B.
Published: February 2005

Pancreatic homografts were placed in the cheek pouches of normal and diabetic hamsters. Blood samples were taken at intervals for the next four weeks. The results were tabulated according to the fate of the implant: whether it was still growing after three weeks or whether it was rejected prior to that time. Among normal animals with good growth, there was an elevation of both the leucocyte and neutrophil counts, the increase being much greater when the grafts were rejected early. In severe diabetics, the increase in both parameters was less than in the controls, regardless of the fate of the graft. The most striking and consistent changes in the serum proteins involved the alpha‐2 and gamma globulins. Among controls the alpha‐2 fraction was as much as three times normal during the first post‐transplant week while the gamma globulin was elevated up to 80% above normal in the third week. In diabetics, the alpha‐2 fraction tended to be below normal while there was no significant increase in the gamma globulin.
On the submicroscopic organization of the myelinated sympathetic nerve fiber in the frog (Rana pipiens)
Authors: Pick Joseph
Published: February 2005

Existing descriptions of the ultrastructure of myelinated nerve fibers were confirmed and extended on methacrylate‐ and Epon‐embedded sympathetic rami of the frog. The nerve fiber was not surrounded by a basement membrane, but by collagen. The Schwann cell contained fibrils, dark granules, mitochondria and also smooth‐edged vesicles which probably transported material into the nerve fiber. Profiles of large vesicles and of collaterals of the main nerve fiber, found in the Schwann cell, were interpreted as the corpuscles of Elzholz and Reich. The presence of cytoplasm between axolemma and myelin was considered as areas of transition of myelinated and tunicated fibers. Existing descriptions of the ultrastructure of the node of Ranvier were confirmed, but the occurence of Schmidt‐Lanterman indentations remained somewhat doubtful. The axon contained filaments, dark granules, mitochondria and a great variety of vesicles; their interpretation was difficult because of the unknown submicroscopic differences of sympathetic, somatic motor and afferent nerve fibers. Concurring with other authors, some vesicles with a light center may have been concerned with acetylcholinesterase activity. It was speculated that dark‐cored vesicles represented probably catecholamine bodies and others were tentatively related to mitochondria formation. Some electron dense granules may have derived from RNA particles in the perikaryon of the neuron.
The bone matrix adjacent to lacunae and canaliculi
Authors: Mjör Ivar A.
Published: February 2005

Three techniques, phase contrast microscopy, microradiography, and electron microscopy, have been used to study the variation in mineralization and presence of collagen fibers in the bone matrix adjacent to lacunae and canaliculi. Undecalcified, partially decalcified and fully decalcified sections of normal bone from old individuals have been studied. No stains were used. A fairly good correlation of the results obtained with these techniques could be demonstrated as far as the degree of mineralization is concerned. A zone of modified matrix is found adjacent to lacunae and canaliculi and this zone is prone to hypermineralization. In certain areas, especially in interstitial bone, lacunae may become completely obliterated with a hypermineralized material. Collagen fibers are found at the surface of the lumen of lacunae and canaliculi. The arrangement of these fibers is in most cases different from that in the adjoining bone matrix producing a well delimited zone which separates the lacunae and canaliculi from the rest of the matrix. Microradiography of bone sections partially decalcified in EDTA indicates that decalcification in vitro may result in an initial preferential decalcification of areas previously hypercalcified.
Palate morphogenesis in mouse embryos after x‐irradiation
Authors: Callas Gerald , Walker Bruce E.
Published: February 2005

The development of cleft palate after x‐irradiation was studied in mice of the C57BL strain. Progress in palate development was evaluated with reference to chronological age, morphological rating and weight of the embryos. Movement of the palatine shelves from the sagittal to the horizontal plane was found to have been retarded by x‐irradition. Measurements of head and palate did not show any consistent disproportionality of palate growth in the x‐irradiated embryos except that which resulted from retardation of shelf movement.

X‐irradiation affected A/Jax strain litters more severely than C57BL strain litters according to cleft palate frequency and average palate stage at eighteen and one‐third days postconception.
The decidual cell response in the golden hamster
Authors: Turnbull John G. , Kent George C.
Published: February 2005

Decidual cell responses elicited by mechanical uterine trauma applied at two loci in one or both horns two full days after sterile mating were studied in 70 pseudoprgnant hamsters. The antimesometrial response was overt near the middle of the fourth 24‐hour interval post coitus and the mesometrial response appeared one day later. The response was maximal during the seventh and eighth 24‐hour intervals post coitus, necrosis commenced near the end of the eighth and total separation of the necrotic mass from the endometrium was complete one full day later. Glycogen appeared in the antimesometrial region before the mesometrial response was overt and later filled most of the cells of both regions. Sheathed arteries were prominent at the utero‐mesometrial junction.
Enlargement of the ulnar nerve behind the medial epicondyle
Authors: Chang K. S. F. , Low W. D. , Chan S. T. , Chuang Adson , Poon K. T.
Published: February 2005

Enlargement of the ulnar nerve behind the medial epicondyle was noticed in museum and demonstration specimens and also in the dissection room cadavers. An investigation was carried out to study the incidence and character of the enlargement entirely from fresh autopsy cases, which included 400 ulnar nerves from 200 autopsy cadavers of Chinese subjects of all ages. The enlargement was graded into three categories — slight, moderate, and marked. Histological sections, 40 μthick and stained with H. & E., were examined. Twenty nerves from ten adult bodies were tested under stress for extensibility along the length of the nerve. Fortynine per cent of the ulnar nerves and 60.5% of cadavers of the total sample showed this enlargement, the incidence being greater in males than in females and slightly greater in the right limb than the left limb. Slight and moderate enlargement occurred in all ages; marked enlargement occurred only in ages over 35. The enlargement presented a normal histological picture; the enlargement was due to an increase of connective tissue present. The experimental results of extensibility along the length of the nerve showed the retro‐epicondylar region, whether enlarged or not, to be more extensible than the rest of the nerve. While there seemed to be a tendency of a decrease of extensibility with enlargement, the correlation between extensibility and enlargement was insignificant statistically.
Anomalous pregnancies in the ia strain of rat
Authors: Mohammed Clive I. , Mardfin Dorothy F.
Published: February 2005

Breeding records of the ia strain of rats have shown interesting cases of anomalous pregnancies where second litters are delivered either before or soon after weaning the first litter. This strain is characterized by a retardation of bone resorption which is inherited as a simple Mendelian recessive factor.

Heterozygous and homozygous males are mated with females of both genotypes. One male and four females are kept in a breeding cage and the female rat is isolated either in the late stage of pregnancy or soon after birth of the litter.

Nineteen anomalous pregnancies have been reported and the occurrence of the anomaly has been attributed to copulation during pregnancy. The ancestry of 13 cases is traced to four animals, two homozygous males and two heterozygous females, and the genetic pattern has been demonstrated.
The mouse uterine surface epithelium during the estrous cycle
Authors: Fuxe Kjell , Nilsson Ove
Published: February 2005

Four groups, each containing six three‐month old virgin mice of the CBA strain have been used. The four groups represent different stages of the ovarian cycle, namely proestrus, estrus, metestrus, and diestrus.

The uterine tissues have been both fresh frozen and fixed in a Champy solution. The fresh frozen specimens have been sectioned in a cryostat, postfixed, and used for fluorescence, polarization, and phase contrast microscopy or stained with Sudan Black, osmic acid, toluidin blue, or the PAS‐technique. The specimens, fixed in the Champy solution, have been embedded in PEG and sectioned for analysis of osmophilic substance.

The lipid granules of the surface epithelium are numerous in the whole cell during diestrus. In estrus, only a small basal rim of granules is left. The lipid granules are neither autofluorescent nor anisotropic.

The PAS‐positive secretory products are most prominent during estrus, and consist during this stage of cytoplasmic granules, a layer on the cell surface, and an irregular substance in the lumen. In diestrus, only a few cytoplasmic granules are observed.

The basement membrane is thick and undulating in diestrus and metestrus, but thin and even in estrus. The present investigation has not revealed any vacuolar degeneration of the uterine epithelium nor any fading and disappearance of its basement membrane in late estrus and in metestrus as noticed by earlier workers.
Cholinesterases in the tongue of the potto (Perodicticus Potto)
Authors: Hodosh Milton , Montagna William
Published: February 2005

The tongue has three circumvallate papillae, arranged in a triangle ahead of the foramen caecum. Gustatory buds are found only on the walls of the vallate papillae and at the surface of the fungiform papillae. The gustatory cells contain acetylcholinesterase; the sustentacular cells contain no such enzymes. A subepithelial network of nerve fibers, containing acetyl‐and butyrylcholinesterases is parallel to the surface of the tongue and extends into the connective tissue cores of all papillae. Numerous pleomorphic end organs are found below all four types of papillae. These abound in acetyl‐and butyrylcholinesterases. The dorsal subepithelial blood vessels contain butyrylcholinesterase, and small amounts of acetyl‐cholinesterase. The ventral aspect of the tongue has fewer nerve fibers and end organs than the dorsal surface does. The nerve fibers to the serous glands of von Ebner, and particularly those to the mucous glands contain considerable acetylcholinesterase.
Testosterone suppression of mesenchymal alkaline phosphatase activity and lympho‐epithelial nodule formation in the bursa of fabricius in the embryonic chick
Authors: Ackerman G. Adolph , Knouff Ralph A.
Published: February 2005

The relatively strong alkaline phosphatase activity of the subepithelial mesenchyme of the bursa during the period of lympho‐epithelial nodule formation (12–15 days of incubation) and the close association of vascular channels with surface epithelium at sites of nodule formation suggest the possible role of these factors in induction and/or development of these nodules.

Experimental inhibition of nodular formation and development may be accomplished by the administration of testosterone prior to the onset of this process (e.g., 12th day of incubation). One‐tenth milliliter (2.5 mg) of testosterone propionate in sesame oil (Schering) was administered on the tenth, eleventh and twelfth days of incubation. Bursas from 136 experimental and 64 control embryos were removed on the thirteenth, fifteenth and eighteenth days of development, fixed in cold 80% ethanol and embedded in paraffin. Alkaline phosphatase activity was demonstrated by the Gomori's glycerophosphate procedure using incubation times of one‐half, two and four hours at 37°C.

Testosterone administered on the twelfth day produced a moderate decrease in alkaline phosphatase activity and markedly reduced nodule formation and subsequent development. When administered on the eleventh day, however, alkaline phosphatase activity was greatly reduced and essentially complete inhibition of nodular formation was accomplished.

The possible direct inhibitory effect of testosterone on alkaline phosphatase activity (and possibly other mesenchymal cell functions) and the resulting inhibition of lympho‐epithelial nodule formation during embryogenesis of the bursa of Fabricius is suggested.
Morphogenetic studies of the rabbit XXXV. Comparison of the weights and linear measurements in normal and heterozygous dwarf rabbits of race X
Authors: Latimer Homer B. , Sawin Paul B.
Published: February 2005

This report presents the weights of the skeleton and 11 bones, 26 linear measurements of the bones and 17 measurements of the skull of 35 adult heterozygous (Dwdw) dwarf rabbits of race X.

The female skeleton is slightly heavier but the long bones of the extremities are heavier in the males. The most varible bones are those with much cancellous bone.

As percentages of total skeleton, in rabbits of the same sex, the mandible is the only bone significantly heavier in both sexes of the dwarfs. The ribs and scapula are significantly heavier in normal (dwdw) rabbits.

Measurements of the bones are slightly more variable in the males. Only two of the 26 measurements are significantly longer in each sex, but as percentages of body length, 11 are significantly longer in the males and one in the females. The long bones of the extremities are generally longer and narrower in both sexes of the dwarfs.

The 17 linear measurements of the skull show no significant sex differences. Six of these, as percentages of body length are greater in dwarf and none in normal females. Only two are significantly greater in dwarf males. The skull measurements are slightly larger in males and somewhat larger as percentages in the dwarfs.
On the structural peculiarities of the pituitary in some clupeoid fishes with a note on their probable evolutionary significance
Authors: Sathyanesan A. G.
Published: February 2005

Hilsa ilisha has a well developed sella turcica comparable to that of Polypterus and Epiceratodus. The persistent orohypophyseal duct and parasphenoidal foramen of adult Hilsa ilisha may represent the retention of embryonic features such as those seen in Salmo trutta, Chanos chanos and Elops saurus. Since this duct is considered to be the persistent base of Rathke's pouch, its presence in adult Hilsa ilisha is an archaic feature which may be considered as the repetition of the condition observed in Polypterus, Calamoichthys and Latimeria. The presence of discontinuous orohyphyseal duct in the fry and fingerlings of Engraulis telara and Gadusia chapra suggests that it may be the remnant of an open buccal connection present during the embryonic condition. In all the specimens used in this study the hypophyseal cavity is in the form of a “tube system” restricted to the rostral pars distalis and it is formed by the constricted and separated portion of the diverticuli of the orohypophyseal canal. It is better developed in the adult Hilsa ilisha and Gadusia chapra than in Engraulis telara. This reduction in the prominence of the duct tends towards the reported condition in the “primitive teleosts” the trout and the eel. Though basically the pituitary of the clupeoid fishes described are of the typical teleostean type, the orohypophyseal duct and the hypophyseal cavity in the form of a “tube system” are distinctly chondrostean features. The presence of these features in different degrees of expression in these forms and the expression of ductile and tubular structure in the fry of Chanos chanos, Salmo trutta and Elops saurus together apparently provide a continuous range of variations from the typically chondrostean to that of the higher teleostean type where cavities and ducts are totally absent.