bluuebunny/crossref_metadata_2025 huggingface dataset:
The plasma membrane and matrix vesicles of mouse growth plate chondrocytes during differentiation as revealed in freeze‐fracture replicas
Authors: Akisaka Toshitaka , Gay Carol V.
Published: February 2005

The epiphyseal cartilage in mouse tibia and fibula was investigated with the freeze‐fracture method. Cytodifferentiation of growth plate chondrocytes was found to be marked by changes in both cell membrane and extracellular matrix vesicle membranes. Exocytosis and endocytosis were observed in all zones of differentiation, with endocytosis being predominant in the reserve and proliferative zones and exocytosis occurring with greatest frequency during hypertrophy. Intramembraneous particles (IMPs) on the plasma membrane were distributed evenly on the reserve and proliferative cell membranes, whereas in the hypertrophic zone IMPs tended to be distributed asymmetrically. Several types of matrix vesicles were identifiable on the basis of IMP distribution: IMP‐free, IMP‐aggregated, and IMP‐random. The distribution pattern of IMPs on vesicles varied with differentiation of the chondrocytes. For proliferative and prehypertrophic cells, most matrix vesicles belonged to the IMP‐random category. IMP‐aggregated and IMP‐free matrix vesicles became increasingly frequent in the later stages of differentiation, particularly in the late hypertrophic stage. IMPs were observed more frequently on the convex protoplasmic fracture face of matrix vesicles than on the concave exoplasmic fracture face, as was also observed for the plasma membrane. Matrix vesicles formation appears to occur by budding from chondrocyte projections and bulges at the smooth surfaces of the cells and from cell disintegration. Crystals of mineral were apparent in cross‐fractured matrix vesicles of the calcifying zone, but not in the other zones.
Studies of otoconia in the developing chick by polarized light microscopy
Authors: Ballarino Joanne , Howland Howard C. , Skinner H. Catherine W. , Brothers Edward B. , Bassett William
Published: February 2005

Using polarized light microscopy we were able to observe the mineralization patterns of embryonic and neonatal chick otoconia. We compared preparations of freshly dissected material spread under mineral oil to material that had been treated with various fixatives and dehydration agents. We found that the standard fixation agent, glutaraldehyde, and some immersion oils etche embryonic chick otoconia but that fixation with 70% acetone or 70% alcohol followed by dehydration to 100% acetone or 100% alcohol left the otoconia intact. The size and shape of freshly dissected chick otoconia observed with polarized light microscopy were similar to those of acetone‐fixed, critical‐point‐dried material examined by SEM. Embryonic forms of otoconia were found to have a fluted pattern that was different in morphology from otoconia found in hatched chicks and adults. Embryonic chick otoconia did not exhibit the multifaceted surface morphology seen in embryonic rat otoconia. Comparisons of the same fields of otoconia under phase contrast microscopy and polarized light microscopy indicated that the freshly dissected otoconia of embryos exhibit little or no unmineralized (nonbirefringent) material but that glutaraldehyde‐fixed otoconia exhibited unmineralized areas where etching had occurred. Size frequency distributions of freshly dissected embryonic and mature otoconia in five ages of embryos and hatched chicks were consistent with a hypothesized developmental sequence of otoconia.
Reconstruction of a type‐B configuration monkey sertoli cell: Size, shape, and configurational and specialized cell‐to‐cell relationships
Authors: Russell Lonnie D. , Gardner Richard J. , Weber James E.
Published: February 2005

A model of a stage‐V monkey Sertoli cell was reconstructed from electron micrographs taken of semiserial sections. The configuration (type‐B) was one in which spermatids were positioned near the lumen, their heads occupying shallow cylindrical recesses at the apical portion of the Sertoli cell. The cell volume was calculated to be 4,100 μm3, the surface area 2,400.68 μm2, and the surface‐to‐volume ratio 0.58:1. The reconstructed cell extended from the basal lamina to the tubular lumen and was generally of the tall columnar type although its surface contour was highly irregular. The dimensions of the cell [centripetal (68.46 μm), circumferential (18.40 μm), and longitudinal (21.63 μm)] were determined and cell surfaces designated. Relative and absolute surface areas of the reconstructed cell which faced other Sertoli cells, germ cells, basal lamina, and tubular lumen were calculated. Junctions and surface specializations were enumerated, catalogued, and depicted on diagrams of the cell surface. Where appropriate, type‐A rat and type‐B monkey Sertoli cells were compared and discussed. Morphometry was utilized to analyze the relative surface areas of germ cells adjoining the reconstructed cell to determine the percentage of their surface facing cellular and acellular elements, and these data were compared to data obtained for the rat.
Cyclic formation and decay of the blood‐testis barrier in the mink (Mustela vison), a seasonal breeder
Authors: Pelletier R.‐Marc
Published: February 2005

The correlations between the germ cell population and the blood‐testis barrier were studied during puberty and throughout the reproductive cycle in a seasonal breeder, the mink. A classification of 12 stages, corresponding to the cellular associations appearing during the cycle of the seminiferous epithelium, was proposed and used to identify the stages of the cycle in pubertal mink. In adult mink, the reproductive cycle was divided into two spermatogenic phases–an active phase lasting 9 months, and an inactive phase lasting 3 months. The active spermatogenic phase was broken down into three distinct periods: the first spermatogenic wave, the peak of spermatogenic activity, and the last spermatogenic wave. Degenerating germ cells were found in comparable and relatively low proportions during puberty and during the first and last spermatogenic waves of the adult reproductive cycle. The permeability of the blood‐testis barrier to intravascularly infused electron‐opaque tracers (i.e., horseradish peroxidase and lanthanum) was tested at the time of the first spermatogenic wave at puberty and throughout the reproductive cycle of the adult. The relationship between epithelial permeability and germ cell populations prevailing during puberty and during the first and last spermatogenic waves of the adult active phase was the same. During puberty, the establishment of the blood‐testis barrier did not coincide with the appearance of a particular step of meiosis but was correlated with the development of a tubular lumen. In adult mink, the barrier cyclically decayed during the last wave of the active spermatogenic phase and reformed during the first wave of the next active phase. The decay and the reformation of the barrier were not coincident with the appearance or disappearance of a particular generation of the germ cell population from the seminiferous epithelium but were correlated with cyclic cytological changes in Sertoli cells and the rhythmic development and occlusion of the lumen. During the peak months of the active spermatogenic phase, however, a blood‐testis barrier secluded spermatogonia and young spermatocytes from older generations of germ cells. It is concluded that (1) during puberty and also during the first and last spermatogenic wave of the adult mink reproductive cycle, the development of germ cells is possible in the absence of a competent, impermeable blood‐testis barrier, and (2) the transient presence of a permeable epithelial barrier does not initiate an autoimmune response of sufficient magnitude to cause destruction of the seminiferous epithelium.
Gill microcirculation of the air‐breathing climbing perch, Anabas testudineus (Bloch): Relationships with the accessory respiratory organs and systemic circulation
Authors: Olson K. R. , Munshi J. S. D. , Ghosh T. K. , Ojha J.
Published: February 2005

The general macrocirculation and branchial microcirculation of the air‐breathing climbing perch, Anabas testudineus, was examined by light and scanning electron microscopy of vascular corrosion replicas. The ventral aorta arises from the heart as a short vessel that immediately bifurcates into a dorsal and a ventral branch. The ventral branch distributes blood to gill arches 1 and 2, the dorsal branch to arches 3 and 4. The vascular organization of arches 1 and 2 is similar to that described for aquatic breathing teleosts. The respiratory lamellae are well developed but lack a continuous inner marginal channel. The filaments contain an extensive nutritive and interlamellar network; the latter traverses the filament between, but in register with, the inner lamellar margins. Numerous small, tortuous vessels arise from the efferent filamental and branchial arteries and anastomose with each other to form the nutrient supply for the filament, adductor muscles, and arch supportive tissues. The efferent branchial arteries of arches 1 and 2 supply the accessory air‐breathing organs. Arches 3 and 4 are modified to serve primarily as large‐bore shunts between the dorsal branch of the ventral aorta and the dorsal aorta. In many filaments from arches 3 and 4, the respiratory lamellae are condensed and have only 1–3 large channels. In some instances in arch 4, shunt vessels arise from the afferent branchial artery and connect directly with the efferent filamental artery. The filamental nutrient and interlamellar systems are poorly developed or absent. The respiratory and systemic pathways in Anabas are arranged in parallel. Blood flows from the ventral branch of the ventral aorta, through gill arches 1 and 2, into the accessory respiratory organs, and then returns to the heart. Blood, after entering the dorsal branch of the ventral aorta, passes through gill arches 3 and 4 and proceeds to the systemic circulation. This arrangement optimizes oxygen delivery to the tissues and minimizes intravascular pressure in the branchial and air‐breathing organs. The efficiency of this system is limited by the mixing of respiratory and systemic venous blood at the heart.
Morphology and vascular anatomy of the accessory respiratory organs of the air‐breathing climbing perch, Anabas testudineus (Bloch)
Authors: Munshi J. S. D. , Olson K. R. , Ojha J. , Ghosh T. K.
Published: February 2005

The vascular organization and endothelial cell specialization of the air‐breathing organs of Anabas testudineus were examined by light and scanning electron microscopy of fixed tissue and vascular corrosion replicas. The vessels supplying blood to the lining of paired suprabranchial chambers and the plicated labyrinthine organs within the chambers are tripartite, having a median artery and paired, lateral veins. Hundreds of respiratory islets, the functional units of gas exchange, cover the surfaces of both the chamber and labyrinthine organ. A median islet artery supplies the central aspect of each islet and gives rise to numerous short arterioles from which the transverse channels are formed. Transverse channels are parallel capillary‐sized vessels that extend in two rows away from the medial arterioles and drain laterally into one of two lateral islet veins. Basally situated single rows of endothelial cells lining the transverse channels form thick, evaginated, tongue‐like cytoplasmic processes that project freely into the lumen from the tissue side of the channel. Other thin, septate, cytoplasmic exensions of the same cells form valve‐like septa that extend across the channel. Both the septa and tongue‐like processes appear to direct the red blood cells to the epithelial side of the channel and thus decrease the diffusion distance between the air and red cell. A large sinusoidal space lies under the transverse channels and may support the channels and even elevate them during increased oxygen demand. The epithelium covering the transverse channels is smooth, which enhances air convecton and minimizes unstirred layer effects. The epithelium between the channels contains microvilli that may serve to trap bacteria or particulates and to humidify the air chambers.
Light and electron microscope observations of the lymphatic drainage units of the peritoneal cavity of rodents
Authors: Tsilibary Effy C. , Wissig Steven L.
Published: February 2005

Fluid, particles, and cells are taken up from the peritoneal cavity by lymphatic drainage units, which, in the mouse and rat, are located along the peritoneal surface of the muscular portion of the diaphragm. The drainage units are composed of three specifically differentiated components: a lymphatic lacuna, a covering of lacunar mesothelium, and intervening submesothelial connective tissue. The units are drained by connecting lymphatic vessels that cross the diaphragm to empty into collecting lymphatic vessels running along the pleural surface of the diaphragm. The collecting lymphatics empty into parasternal lymphatic trunks. In this report, we briefly review critical features of the drainage apparatus and describe new observations, summarized below, about their structure.

Around the rim of stomata, the mesothelial openings that lead into the lymphatic lacunae, plasma membranes of lacunar mesothelial cells and of lacunar enidothelial cells abut but are not linked to one another by recognizable junctional specializations. Lacunarendothelial cells often extend valve‐like processes that bridge the distal end of the channel beneath the stoma. The configuration of the endothelial processes may be complex. Occasionally, processes from fibroblasts in the submesothelial connective tissue adjacent to stomata make contact with the interstitial surface of lacunar endothelial cells. A discontinuous elastic layer in the submesothelial connective tissue spans the roof of each lacuna. Connecting and collecting lymphatics, which drain lymphatic lacunae, possess endothelial valves. Possible functions for each of these newly described structural features are discussed.
Neurogenesis in the vomeronasal epithelium of adult garter snakes: 3. Use of H3‐thymidine autoradiography to trace the genesis and migration of bipolar neurons
Authors: Wang Ruu Tong , Halpern Mimi
Published: February 2005

Use of H3‐thymidine autoradiography and unilateral vomeronasal (VN) axotomy has permitted us to demonstrate directly the existence of VN stem cells in the adult garter snake and to trace continuous bipolar neuron development and migration in the normal VN and deafferentated VN epithelium in the same animal.

The vomeronasal epithelium and olfactory epithelium of adult garter snakes are both capable of incorporating H3‐thymidine. In the sensory epithelium of the vomeronasal organ, H3‐thymidine‐labeled cells were initially restricted to the base of the undifferentiated cell layer in animals surviving 1 day following H3‐thymidine injection. With increasing survival time, labeled cells progressively migrated vertically within the receptor cell column toward the apex of the bipolar neuron layer. In both the normal and denervated VN epithelium, labeled cells were observed through the 56 days of postoperative survival. In the normal epithelium, labeled cells were always located within the matrix of the intact receptor cell columns. However, labeled cells of the denervated epithelium were always located at the apical front of the newly formed cell mass following depletion of the original neuronal cell population. In addition, at postoperative days 28 and 56, labeled cells of the denervated VN epithelium achieved neuronal differentiation and maturation by migrating much farther away from the base of the receptor cell column than the labeled cells on the normal, unoperated contralateral side tralateral side.

This study directly demonstrates that basal cells initially incorporating H3‐thymidine are indeed stem cells of the VN epithelium in adult garter snakes. These stem cells differentiate and develop into neurons in the normal VN epithelium for normal neuronal turnover. Stem cells, which incorporated H3‐thymidine prior to unilateral VN axotomy, after axotomy differentiate and develop into neurons in the regenerating VN epithelium for replacement of the axotomized neurons. The life span of the labeled VN neurons may exceed 56 days. Postnatal neurogenesis during regenerative repair of the VN organ, however, is accompanied by rapid undifferentiated cell proliferation following axotomy, rapid cell migration, and a tendency for rapid cell turnover.
Ontogeny of langerhans cells in human embryonic and fetal skin: Cell densities and phenotypic expression relative to epidermal growth
Authors: Foster Carolyn A. , Holbrook Karen A.
Published: February 2005

Langerhans cells (LCs) positive for HLA‐DR antigens were present in developing human epidermis by at least 7 weeks estimated gestational age (EGA). Most were negative for CD1 (T6) until 12‐13 weeks EGA when they underwent a dramatic increase in CD1 reactivity. To gain insight into the density of LCs during ontogeny and to assess whether their distribution was coordinated with epidermal growth, the number of cells positive for both HLA‐DR and CD1 antigens was determined relative to surface area and to volume of developing, interfollicular epidermis. LCs differed in their phenotype, distribution (follicular vs. interfollicular), size, and shape between 7 and 21 weeks EGA; however, during this period they maintained a statistically equivalent (P > .25) density (65 cells/mm2 and 1,750/mm3) even though the epidermis increased in thickness and the fetus rapidly expanded its surface area. While LCs were evenly distributed within the epidermal sheets at all gestational ages, those in embryonic skin were much smaller and less dendritic than the older cells. The density, size, and shape of LCs in developing skin seemed to be independent of epidermal status (e.g., thickness, stage of keratinization, and number of cell layers) but rather were correlated with gestational age. The number of fetal LCs, through at least 23 weeks EGA, was only 10‐20% of the adult LC density. Thus, we can conclude that the increase in LC density to adult levels must occur either during the third trimester or after birth.
Light microscopic study of the hypophyseal angioarchitecture in the rabbit
Authors: Foster W. G. , Boyd W. H.
Published: February 2005

This study describes the hy‐pophyseal angioarchitecture found in 79 adult New Zealand white rabbits. The pituitary glands and attached hypothalami were removed and carefully processed following routine histological methods, and the vascular organization was studied by light microscopy. Whole mounts of the pituitary median eminence complex were prepared and studied with a binocular dissecting microscope employing transmitted and epi‐illumina‐tion.

Arterial blood was found to be directed primarily to the neurohypophysis by the superior hy‐pophyseal artery (SHA) and the inferior hypophy‐seal artery (IHA). A direct arterial blood supply was found to the adenohypophysis, but was limited solely to the pars intermedia by branches of the anterior hypophyseal artery (AHA) and the IHA. Capillaries of the pars intermedia were subdivided into an intermediate and a superficial plexus. The superficial plexus was situated between the intermediate plexus and the capillaries of the infundibular process. Capillaries of the superficial plexus did not form anastomoses between themselves, but ramified into the intermediate plexus to form a dense network of anastomosing capillaries that were continuous with capillaries of the pars distalis. A direct arterial blood supply was found only to the superficial plexus.
Expression of novel basement membrane components in the developing human kidney and eye
Authors: Kleppel M. M. , Michael A. F.
Published: February 2005

The distribution of two novel human, basement‐membrane (BM) collagens has been characterized by immunohistochemical analysis of developing and mature tissue using monoclonal antibodies specific for the non‐collagenous (NC1) domain of each molecule. A distribution more restricted than that of type IV collagen was observed. In the kidney, the 28K parent molecules appear relatively late, at the early capillary‐loop stage of glomerular development, whereas type IV collagen is present in all BM, including those of the ureteric bud, S‐form, primitive glomerulus, and vessels. Antibody to the Alport familial nephritis antigen (a 26K peptide), which is missing from epidermal BM and glomerular BM in Alport syndrome, reacted with the ureteral bud BM and all stages of glomerular BM development from the early capillary‐loop stage onward, but not with BM of more primitive glomeruli (vesicles and S forms).

In the human fetal eye, the collagen molecules from which the 28K NC1 peptides are derived appear later in development than type IV collagen. They are present in trace amounts in Bruch's membrane but are not detected until after birth in the retinal internal limiting membrane and cuticular and non‐pigmented epithelial BM of the ciliary process. In contrast, the BM of the lens capsule and Descemet's membrane were reactive with anti‐28K antibodies early in development. In all instances, the 28K peptides are detected in BM that also contain the Alport antigen, although the latter is present in some BM not containing the 28K peptides. The distribution of Alport antigen and type IV collagen in developing eye is similar to that observed in the mature eye. The 28K parent molecules appear to be expressed in concert with the maturation of the BM, coincident with fusion of glomerular endothelial and epithelial BM, whereas the lens capsule BM and Descemet's membrane contain these restricted components much earlier in gestation.
Germinal cell ectopism in the strepsirhine prosimian Galago crassicaudatus crassicaudatus
Authors: Yoshinaga Kazuya , Hess David L. , Hendrickx Andrew G. , Zamboni Luciano
Published: February 2005

The presence of germinal cells outside of the embryonal and fetal gonads of the strepsirhine prosimian Galago crassicaudatus crassicaudatus is described. Forty‐three embryos and fetuses from day 26 or 27 of gestational age to near term were studied: more than 90% possessed germinal cells in ectopic sites situated either far from (extragonadal ectopism) or close to the gonads (perigonadal ectopism). The first sites were the walls of the aorta and mesenteric artery, the stroma between the aorta and the cardinal vein and the retroperitoneal neuroganglia. The second were the mesenchyme dorsal to the gonads and around the vestigia of the mesonephric glomeruli and tubules, and the rete ovarii and testis. The ectopic cells were generally present in conspicuous numbers, in some animals being more numerous than in the gonads. Those situated far from the gonads underwent degeneration and decreased significantly in numbers during post‐embryonal stages of development, while the others remained numerous and functionally active up to near term. While the differentiation of the extragonadal germinal cells after day 60 of gestational age could not be studied due to technical difficulties, the XX and XY cells in perigonadal sites appeared to follow patterns of differentiation identical to those of their entopic counterparts.
Identification of a program of contractile protein gene expression initiated upon skeletal muscle differentiation
Authors: Sutherland Colin J. , Esser Karyn A. , Elsom Vicki L. , Gordon Monica L. , Hardeman Edna C.
Published: February 2005

The functional diversity of skeletal muscle is largely determined by the combinations of contractile protein isoforms that are expressed in different fibers. Just how the developmental expression of this large array of genes is regulated to give functional phenotypes is thus of great interest. In the present study, we perform a comprehensive analysis of contractile protein isoform mRNA profiles in skeletal muscle systems representing each generation of fiber formed: primary, secondary, and regenerating fibers. We find that in each system examined there is a common pattern of isoform gene expression during early differentiation for 5 of the 6 gene families we have investigated: myosin light chain (MLC)1, MLC2, tropomyosin, troponin (Tn)C, and TnI. We suggest that the common isoform patterns observed together represent a genetic program of skeletal muscle differentiation that is independent of the mature fiber phenotype and is found in all newly formed myotubes. Within each of these contractile protein gene families the program is independent of the isoforms of myosin heavy chain (MHC) expressed. The maintenance of such a program may reflect a specific requirement of the initial differentiation process. © 1993 wiley‐Liss, Inc.
Dynamic changes in ovarian c‐kit and Steel expression during the estrous reproductive cycle
Authors: Motro Benny , Bernstein Alan
Published: February 2005

W and Steel mutant mice exhibit similar developmental defects in melanogenesis, haematopoiesis, and gametogenesis. Consistent with the cell autonomous and microenvironmental nature of W and Sl mutations, respectively, W encodes the c‐kit receptor tyrosine kinase while Steel enclodes the Kit ligand. Both c‐kit and Steel are expressed in various cells in which no corresponding mutant phenotype has yet been demonstrated. In the adult ovary, certain stromal‐derived cells (theca and interstitial), as well as oocytes, express c‐kit, while granulosa cells express Steel. We show here that the cessation of oocyte growth, at the transition of the follicle to the antral stage, is associated with the cessation of Steel expression in the cumulus granulosa cells in the vicinity of the oocyte. These observations suggest a role for the Kit signaling pathway in oocyte growth or in meiotic arrest. In addition, the cyclic secretion of luteinizing hormone immediately and dramatically results in elevated Steel expression in mural granulosa cells and decreased levels of c‐kit transcripts in stromal‐derived cells. This influence of the estrous reproductive cycle on c‐kit/Steel expression suggests that the Kit signaling pathway, in addition to its previously described role in primordial germ cell development, is involved in follicular development in the adult female. © 1993 Wiley‐Liss, Inc.
Distribution of CD9 in the developing and mature rat nervous system
Authors: Tole Shubha , Patterson Paul H.
Published: February 2005

CD9 is a cell surface protein implicated in intercellular signaling that has been identified in selected cell types of the hematopoietic system. To begin a study of the role of CD9 in the developing and adult nervous system, we used the anti‐rat CD9 monoclonal antibody ROCA2 to determine the distribution of this protein. The identity of the antigen in these tissues was confirmed by immunoblotting and peptide sequencing. Early embryonic sympathetic and dorsal root ganglion sensory neurons and adrenal chromaffin cells all express CD9. ROCA2 also labels the somas, axons, and growth cones of cultured sympathetic and sensory neurons. In the central nervous system (CNS), CD9 is transiently and specifically expressed in embryonic spinal motorneurons. In the adult, central and peripheral glia intensely express CD9. Thus, CD9 is developmentlly regulated in a variety of peripheral and central neurons and glia, including proliferating progenitors as well as mature cells. These findings suggest that CD9 may have diverse roles in the nervous system. © 1993 Wiley‐Liss, Inc.
Accumulation of mRNAs encoding synaptic vesicle‐specific proteins precedes neurite extension during early neuronal development
Authors: Marazzi Giovanna , Buckley Kathleen M.
Published: February 2005

Synaptic vesicles are essential for neuronal synaptic function. We have analyzed the temporal and spatial pattern of mRNA accumulation of two integral membrane proteins specific for synaptic vesicles (synaptophysin and SV2) and a small GTP‐binding protein associated with the vesicles (rab3a), using in situ hybridization to mouse embryonic tissue sections. Our results indicate that transcription of these mRNAs is not synchronous in the embryo. Detectable levels of synaptophysin and rab3a mRNAs appear during early neurulation (embryonic day [ED] 9.5) both in the CNS and PNS, whereas SV2 mRNA is not observed before ED 10.5. We have also compared the accumulation of these synaptic vesicle protein transcripts during neuroblast proliferation and neuronal differentiation in vitro, using as a model system the embryonic carcinoma cell line P19 which can be induced to differentiate into neurons and glial cells. We observe that transcripts for all three proteins appear in neurons virtually simultaneously soon after withdrawal from the cell cycle. These data suggest that the program of differentiation in vitro is similar to that observed in vivo, but markedly accelerated. In both embryos and P19 cells, transcripts for these three proteins are detectable at a time when most of the neurons have withdrawn from the cell cycle, but prior to neurite extension and synapse formation. © 1993 Wiley‐Liss, Inc.
Evaluation of the chick wing territory as an equipotential self‐differentiating system
Authors: Stephens Trent D. , Baker Wallace C. , Cotterell Joseph W. , Edwards Dale R. , Pugmire Douglas S. , Roberts Steve G. , Shaker Mohammad R. , Willis Howard J. , Winger Kirk P.
Published: February 2005

Harrison (1918: J. Exp. Zool. 25: 413–461) described a developmental field as an “equipotential self‐differentiating system.” The present study was undertaken to address the question: To what extent can the pre‐limb territory of a chick embryo be considered a developmental field? To what extent is the chick pre‐limb territory an equipotential self‐differentiating system? Two sets of experiments were undertaken to address these questions: (1) Whole and half limb territories were explanted to the celoma of host embryos, and (2) portions of the wing territories were extirpated. The wing exhibited the quality of self‐differentiation after stage 12, in that the isolated wing territory, grafted to a host celom, could form limbs beginning at stage 12 (however, complete wings formed only from wing territories of stage 16 and older). On the other hand, the chick wing territory did not appear to exhibit equipotentiality. No posterior half limb graft formed normal limbs, and only in two exceptional cases did anterior half limb grafts form limbs. If part or all of the wing territory was removed from chick embryos, normal limbs formed in less than 15% of the cases after stage 15, in about 30% of the cases at stages 13 and 14, but in over half the cases at stages 10–12. Wound healing and reintiation of limb potential may be responsible for the higher incidence of limb formation at the younger ages. © 1993 Wiley‐Liss, Inc.
Control of calbindin‐D28K expression in developing mouse kidney
Authors: Davies Jamie
Published: February 2005

Calbindin‐D28K, a cytoplasmic calcium‐binding protein located in restricted regions of mature metanephric kidneys, is expressed in a complex manner by kidneys developing in culture. In developing collecting duct, it is present in all regions and is independent of 1,25‐dihydroxy‐vitamin D3 [1,25(OH)2D3]. In developing nephrons, its expression is restricted to the most distal end of the growing tubule, commences during differentiation of specialized tubule segments, and depends completely on the presence of 1,25(OH)2D3. The Wolffian ducts of mesonephric kidneys also express calbindin independently of 1,25(OH)2D3, as do the Wolffian duct‐derived connecting tubules, but mesonephric nephrons show no expression of the molecule. By displaying separate tissue‐specific controls for calbindin expression, cultured kidney rudiments offer a very accessible system for investigation of the control mechanisms involved. © 1994 Wiley‐Liss, Inc.
Differentiation, extracellular matrix synthesis, and integrin assembly by Drosophila embryo cells cultured on vitronectin and laminin substrates
Authors: Gullberg Donald , Fessler Liselotte I. , Fessler John H.
Published: February 2005

Two contrasting substrates, Drosophila laminin and human vitronectin, caused determined primary Drosophila embryo cells to follow alternate intermediate differentiation steps without affecting the final outcome of differentiation. Integrin αPS2βPS3 was essential for the initial spreading of myocytes on vitronectin: focal contacts rich in βPS3 integrins formed and were connected by actin‐ and myosin‐containing stress fibers. While αPS2βPS3 was unnecessary for myotube formation on laminin, it was required for the subsequent change to a sarcomeric cytoarchitecture. The differentiating primary cultures synthesized integrins and assembled them into detergent‐insoluble, cytoskeleton‐associated complexes. Collagen IV, laminin, glutactin, papilin, and other other extracellular matrix proteins were made primarily by hemocytes and were secreted into the medium. Further differentiation within the cultures was influenced by secreted components and by later addition of vitronectin or bovine serum. Comparison of the differentiation of various cell types on the two substrates showed that vitronectin provided a selective advantage for the differentiation of myocytes, with enrichment over epithelia, epidermal cells, and neurites. © 1994 Wiley‐Liss, Inc.
Expression of the platelet‐derived growth factor β receptor during organogenesis and tissue differentiation in the mouse embryo
Authors: Shinbrot E. , Peters K. G. , Williams L. T.
Published: February 2005

In this study we used in situ hybridization to localize expression of the platelet‐derived growth factor β (PDGFβ) receptor mRNA during organogenesis in the mouse embryo (E 9.5–16.5). Expression was first seen in periaortic mesenchyme (E 9.5–10.5). Later (E 12.5–E 16.5), the receptor was expressed in the mesenchymal component of many developing tissues and organs, particularly derivatives of the primitive gut. The expression was exceptionally high in mesenchyme directly supporting an epithelium, typical of many developing organs such as the trachea and intestine. However, as the mesenchyme differentiated into smooth muscle, PDGFβ receptor mRNA was no longer detected. The expression of the PDGFβ receptor mRNA in mesenchymal components of developing organs, along with its absence in epithelial tissues, indicates that it may play a role in mesenchymal‐epithelial interactions during organ development. Somewhat unexpectedly, the PDGFβ receptor was highly expressed in the endothelium of small blood vessels and vascular structures such as the hyaloid plexus and choroid plexus. In large blood vessels, PDGFβ receptor mRNA was found in the mesenchyme surrounding the endothelium. This suggests that the PDGFβ receptor is involved in growth and development of blood vessels. © 1994 Wiley‐Liss, Inc.
Stage and tissue‐specific expression of the alcohol dehydrogenase 1 (Adh‐1) gene during mouse development
Authors: Vonesch Jean‐Luc , Nakshatri Harikrishna , Philippe Murielle , Chambon Pierre , Dollé Pascal
Published: February 2005

The Adh‐1 gene product, ADH‐A2, the only known murine class I alcohol dehydrogenase, is able to oxidize retinol (vitamin A) into retinaldehyde, the first enzymatic step in the conversion of retinol into its biologically active metabolite retinoic acid. We have investigated the developmental expression pattern of Adh‐1 transcripts by in situ hybridization. Transcripts were first detected by embryonic day 10.5 in the mesonephros mesenchyme. During the following gestational days, Adh‐1 transcripts were detected in several mesenchymal areas, such as nasal, laterocervical, and genital regions. Adh‐1 transcripts were also detected in a small ectodermal domain at the anterior margins of both forelimbs and hindlimbs. During late fetal development, Adh‐1 transcripts were found essentially in the epidermis and in a number of tissues which continue to express the gene after birth, such as liver, kidney, gut epithelium, adrenal cortex, testis interstitium, and ovarian stroma. In contrast, a strong expression of Adh‐1 was found in the mesenchyme of developing lungs, but not in the adult organ. This highly regulated expression of Adh‐1 is discussed with respect to the local synthesis of retinoic acid during development. Although the promoter of the human counterpart of Adh‐1 contains a retinoic acid response element (Duester et al. [1991] Mol. Cell. Biol. 11:1638–1646), we report that this element is not conserved in the murine gene. Consistently, Adh‐1 promoter‐containing reporter constructs were not retinoic acid‐inducible in cotransfections assays with RARs and/or RXRs, suggesting that retinoic acid regulation of Adh‐1 differs from that of the human gene. © 1994 Wiley‐Liss, Inc.
Rearrangement of epithelial cell types in an insect wing monolayer is accompanied by differential expression of a cell surface protein
Authors: Nardi James B.
Published: February 2005

The distribution of adhesive molecules on surfaces of cells represents covert information for specifying positions of cells within a tissue. In insect wing epithelia where cells are arranged in two monolayers separated by an extracellular space, these adhesive molecules are found on basal and lateral surfaces of cells. Protein 3B11 is one surface protein whose expression changes in concert with movement and alignment of cells in wing monolayers of Manduca as well as with migration of tracheoles between the two monolayers of the wing. As epithelial cells segregate into periodic, transverse rows of alternating cell types (scale cells and generalized epithelial cells), the expression of 3B11 changes from a uniform distribution throughout the epithelial monolayer to a distribution correlated with a cell's final position and phenotype. Initially protein 3B11 is uniformy expressed on nonadherent surfaces of cells, but with the inception of cell rearrangement, differential expression of 3B11 on basolateral surfaces of cells—both adherent and nonadherent surfaces—becomes a function of epithelial cell type. At the completion of the cell movements associated with segregation of cell types, 3B11 is once again uniformly expressed throughout the wing epithelium. Also, as the upper and lower epithelial monolayers interact at their basal surfaces during adult development, 3B11 is expressed at the interface between the two epithelial monolayers and presumably functions in the nonspecific interaction between these monolayers. Examining the expression pattersn of this protein as well as other adhesion molecules in wing epithelia should reveal general rules about either the simplicity or the complexity of the molecular prepatterns that orchestrate overt tissue patterns in epithelial monolayers. © 1994 Wiley‐Liss, Inc.
Gene encoding a novel murine tissue inhibitor of metalloproteinases (TIMP), TIMP‐3, is expressed in developing mouse epithelia, cartilage, and muscle, and is located on mouse chromosome 10
Authors: Apte Suneel S. , Hayashi Kimiko , Seldin Michael F. , Mattei Marie‐Genevieve , Hayashi Masando , Olsen Bjorn R.
Published: February 2005

Remodeling of the extracellular matrix (ECM) is an essential component of normal development and is also involved in the pathogenesis of arthritis and the spread of cancer. The matrix metalloproteinases and their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), play an important role in this context. We have isolated mouse cDNA clones encoding a novel member of the TIMP family, designated TIMP‐3. We have assigned the Timp‐3 locus to the [C1–D1] region of mouse chromosome 10 using both genetic and cytogenetic methods. The conceptual translation product of the Timp‐3 cDNA shows a high degree of similarity with ChIMP‐3, a recently cloned chicken metalloproteinase inhibitor, as well as significant structural similarity with the amino acid sequences of the previously isolated members of this family, TIMP‐1 and TIMP‐2. The pattern of expression of Timp‐3 in the developing mouse embryo is distinct from that previously reported for Timp‐1. Timp‐3 is expressed in cartilage and skeletal muscle, in myocardium, in the skin, oral and nasal epithelium, in the newborn mouse liver, in the epithelium of some tubular structures such as the developing bronchial tree, oesophagus, colon, urogenital sinus, bile duct, in the kidney, salivary glands, and in the choroid plexus of the brain. The patterns of Timp‐3 expression in surface epithelia and in the epithelial lining of many tubular organs suggests that TIMP‐3 may be involved in regulating ECM remodeling during the folding of epithelia and during the formation, branching, and expansion of epithelial tubes. In the mouse placenta, expression is seen in the trophoblast, raising the possibility that TIMP‐3 may be involved in regulating trophoblastic invasion of the uterus. We propose a role for TIMP‐3 in musculoskeletal and cardiac development, in the morphogenesis of certain epithelial structures, and placental implantation. © 1994 Wiley‐Liss, Inc.
Low intracellular pH is involved in the early embryonic death of DDK mouse eggs fertilized by alien sperm
Authors: Leclerc Catherine , Becker David , Buehr Mia , Warner Anne
Published: February 2005

Intracellular pH was measured in normal 8‐cell stage mouse embryos and in embryos from a cross between DDK females and C3H males. DDK/C3H embryos display the DDK syndrome and spontaneously begin to decompact toward the late 16‐cell stage. Ultimately, 90% fail to form blastocysts. Normal embryos have a resting intracellular pH close to neutrality. In DDK/C3H embryos a substantial proportion (46%) has an intracellular pH below 6.7. An equivalent proportion of DDK/C3H embryos was found previously to show slow communication through gap junctions at the 8‐cell stage. This is probably a consequence of low intracellular pH. In normal embryos the weak acid, butyric acid, decreased intracellular pH and slowed the transfer of Lucifer Yellow through gap junctions. Normal embryos treated with butyrate for between 1 and 6 hr beginning at the 8‐cell stage and cultured for 24 hr, reproduced the DDK/C3H phenotype. After 48 hr some butyrate treated embryos recovered, while others remained as decompacted morulae. Treatment of control and DDK/C3H 8‐cell stage embryos with dibutyryl cyclic AMP or forskolin, which will increase intracellular cyclic AMP, speeded gap junctional communication. Forskolin treatment prevented expression of the DDK syndrome in DDK/C3H embryos, although the rescue was transient and the syndrome returned when forskolin was removed. The finding that the DDK syndrome is manifested as low intracellular pH may provide clues to the molecular basis of the defect. © 1994 Wiley‐Liss, Inc.
Vascular anomalies of the face and neck
Authors: Blair Charles B. , Nandy Kalidas , Bourne G. H.
Published: February 2005

Dissection of a female cadaver revealed striking vascular anomalies in facial and neck regions.

The left facial artery was completely absent; its functions were assumed by two branches of the maxillary. These branches supplied structures normally supplied by them and carried blood to structures typically supplied by the facial artery and its branches. The infraorbital artery replaced the superior labial, lateral nasal and angular arteries; the buccal artery replaced the inferior labial artery.

Venous drainage of the left side of the face and anterior neck regions involved chiefly a single facial vein which arose typically, crossed the mandible, entered the neck and coursed to the suprasternal space. Turning laterad it entered the subclavian vein lateral to the entrance of the internal jugular.

Vascularization of the right side of the face and neck was typical.

Additional anomalies involved branches of the subclavian arteries. On the left side, a vertebral artery originated from the thyrocervical trunk and gave off a small inferior thyroid artery and a much smaller muscular banch. No left ascending cervical artery was evident. A dorsal scapular artery arose fom the third part of the subclavian. On the right side, thyrocervical and costocervical trunks were present branching typically but originating in reverse mediolaterad order.

All branches from the right subclavian artery, including a dorsal scapular, arose from the first part of the subclavian.
Age changes in the blood supply to molar teeth of rats
Authors: Bernick Sol
Published: February 2005

1. Rats, varying in age from one month to over one year, were used to study the changes in the vascular supply to the molar teeth and periodontium as a result of aging. The blood vessels were demonstrated by the saline‐India‐gelatin perfusion method. The jaws and teeth were fixed in a formol‐acetic acid‐alcohol solution, decalcified, dehydrated, and embedded in nitro‐cellulose in the usual manner. The embedded specimens were sectioned at 100–250 μ, cleared by the Spalteholz method and mounted unstained.

2. In immature animals (younger than four months) the pulpal terminal vascular capillary networks were located at the predentin border. As the animals became progressively older, there was a gradual “withdrawal” of the terminal capillary plexuses from the odontoblastic zone so that at eight months of age, all the vascular terminals were restricted in location to the pulpal‐odontoblastic border.

3. In the young animal the vessels supplying the periodontal ligament passed gingivally paralleling the bony surface of the membrane with the cemental side being devoid of vessels. During the process of aging, the above basic pattern was altered in the following manner: (a) The apposition of cellular cementum on the apical third of the root was accompanied by the presence of capillary terminals in or adjacent to the layer of cellular cementum. (b) There was a progressive decrease and eventually a loss of the interseptal vessels and their perforating branches. (c) Vascular twigs originating from the main periodontal vascular trunk were found in areas of cemental resorption indicating their need in the process of repair.
Vaginal cycles in the rat after x‐ray or other damage to one or both ovaries
Authors: Plagge James C. , Krehbiel Robert H.
Published: February 2005

Damage to the rat ovary at 60 days of age causes irregularities in the estrous cycle and leads to continuous cornification of the vagina. These vaginal changes occurred within two to three months after bilateral irradiation (800 or 2,000 r) or after bilateral castration and autotransplantation of a portion of one ovary. Unilateral irradiation or ligation of the ovarian arteries at their junction with the uterine artery produces similar changes within five to seven months. Comparable vaginal changes did not occur in control animals until they reached the age of ten months.
A comparison of autoradiographic and alizarin techniques in the study of bone growth
Authors: Dixon Andrew D. , Hoyte David A. N.
Published: February 2005

Actively growing rats and rabbits received a single intraperitoneal injection of radioactive calcium (2.5 – 10 μc/100 gm) or alizarin red (50 – 100 mg/kg). Contact autoradiographs and gross, macerated dry alizarin specimens were prepared. In addition some alizarin specimens were sectioned serially, without prior decalcification, and the results of the various techniques were compared to determine if morphologic appearance were in agreement.

Many similarities were found in corresponding regions of the radioactive calcium and alizarin preparations which included the tibia, cartilaginous joints of the skull base, the bones of the vault, the olfactory fossa, tympanic bulla and the malar process of the maxilla. In every instance the findings were in agreement, particularly in relation to the pattern of deposition and resorption in the growth of these regions, and the results were confirmed by reference to histologic control material.

It was concluded that radioactive calcium and alizarin red are deposited similarly in growing bones, including those of the skull, and the results which can be obtained by the use of the two substances are fully complementary.