Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Organizers, Embryonic”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1981

[Committed granulomonocytic precursors in human embryonic organs].

By means of a modified Howell semisolid medium it has been established that the relative content of committed stem cells of the myeloid clone in liver and spleen tissues of human fetus, aged between 18 and 24 weeks, is higher by five times than that in the bone marrow of adults. The methods worked out for making preparations of agar cultures and for their morphocytochemical staining may be used for the identification of grown cell elements; they are simple and reproducible.

Cells, Cultured↗
PubMed1976

Cellular development of some embryonic organs and the chorion during the first trimester of human pregnancy.

The DNA, RNA and protein content of chorionic tissue, heart, liver, kidney, lung and brain was estimated in 27 fetuses obtained at termination of pregnancy between 50 and 105 days of menstrual age. For brain, heart and liver, growth appeared to be most rapid at the earliest period studied (50 to 60 days) whereas kidney and lung development was most rapid later in the first trimester. It is suggested that these periods of particularly rapid growth may be the times at which those tissues are most vulnerable to injury.

Brain↗
PubMed1980

Chemically-defined organ culture of embryonic mouse tooth organs: morphogenesis, dentinogenesis and amelogenesis.

Chemically-defined in vitro conditions without serum have been identified which are permissive for embryonic mouse tooth organs to express morphogenesis and cytodifferentiation. In the absence of antibiotics, embryonic extracts, autologous and/or heterologous sera, molar tooth organs from Theiler stage 25 embryos (C57BL/6, A/Jax and Tabby mouse strains) routinely formed discrete dentin and enamel extracellular organic matrices within 10 days of continuous in vitro cultivation. Collagen and non-collagenous protein synthesis and secretion by differentiated cells within explants, between 9 and 10 days in vitro, were studied with light microscopic autoradiography. Finally, explants of embryonic mouse molar tooth organs have been maintained in organ culture for three week without serum supplementation.

Amelogenesis↗
PubMed1983

Cell determination boundaries as organizing regions for secondary embryonic fields.

A model is proposed for pattern formation in secondary embryonic fields. It is stipulated that the boundaries, resulting from the primary embryonic organization of a developing organism, act as organizing regions for secondary embryonic fields, e.g., imaginal discs in insects. This boundary mechanism would allow very reliable pattern formation in the course of development: Primary positional information leads to cells of different determination, separated by sharp borders. At these borders, in turn, positional information would be generated for the next finer subdivision, and so on. This occurs if two or more differently determined cell types (e.g., compartments) cooperate for the production of a morphogenetic substance. A high concentration of the morphogen would appear at the common boundary of the cell types involved. Many experiments reported in the literature, for instance, the formation of duplicated and triplicated insect legs and the regeneration-duplication phenomenon of imaginal disc fragments can be explained under this assumption. The proposed boundary mechanism provides a molecularly feasible basis for the polar coordinate model.

Animals↗
PubMed1983

Computer simulation of organogenesis: an approach to the analysis of shape changes in epithelial organs.

Embryonic development of epithelial organ primordia often involves changes in several parameters, such as cell height, cell width, cell volume, amount of extracellular space, and cell number. Since these changes often occur simultaneously, it becomes difficult to "separate out" the role that each plays in the developmental process. A computer program has been written that allows the shape of epithelial organs to be reproduced based upon measurements of the primordium. A developmental sequence can be simulated by changing the dimensions of the primordium based upon either measurements of the developmental stages or theoretical projections of changes. The primordium is divided into blocks representing groups of cells, based upon characteristics of the different cell groups. The program allows differences in cell height and circular and spiral curvatures of the primordium to be simulated. Analysis of the optic primordium using this method has allowed recognition of several regional changes during optic cup formation. These are sequential constriction of cell apices at the margin of the optic cup, expansion of the apical surface toward the center of the retinal disc, and spreading of the future pigmented layer. Simulation of other organs permits regions of morphogenetic activity to be identified.

Animals↗
PubMed1970

Lysozyme in epiphyseal cartilage. II. The effect of egg white lysozyme on mouse embryonic femurs in organ cultures.

Embryonic mouse femoral cartilage, like the epiphyseal cartilage of the calf scapula, contains large amounts of lysozyme. The addition of egg white lysozyme to organ cultures of embryonic mouse femurs induces unique alterations in the gross and microscopic morphology of the femurs. The sites of these alterations are precisely related to the natural distribution of lysozyme in calf scapula. If the exogenous lysozyme is withdrawn from the culture, the morphological changes disappear, accompanied by a resumption or derepression of growth. The effect on growth is evident only in 17-day embryos. These observations support the idea that lysozyme has a physiological role in cartilage, perhaps related to a regulatory mechanism in bone formation.

Animals↗
PubMed1990

[Estrogen receptor content in human embryo].

Estrogen receptor (ER) content was measured in 27 human embryos, aged 3 to 7 months, with 17-fluoreceinated estrone (17-FE). ER was demonstrated in a uneven distribution pattern in most human embryonic organs. Most embryonic uteri and livers and a few lungs, stomachs and spleens were ER positive. The ER gradually increased with embryonic development in target organs such as the uterus, ovary and testes, as well as in some non-target areas such as mouth and upper digestive system. The ER decreased with embryonic development in the lower digestive system and were maintained at a low level in the lung, heart, brain and lymphoid organs. In the early embryo (3 to 4 months) the ER positive cells (A, B and C type) accounted for a greater proportion of embryonic cells than they did in the late embryonic period (5 to 7 months). The A and B type cell counts fell to the lowest point in the fifth month and increased again in the sixth month. The C and D type cells reached the lowest point in the fourth month in non-target organs but the D type cells then dramatically increased in the uterus, testes and liver. It was suggested that ER play an important role in human embryonic development and differentiation. The ER may influence proliferative ability of early embryonic organs and the late hormone-specific organ growth.

Fetus↗
PubMed1996

The function of the Drosophila argos gene product in the development of embryonic chordotonal organs.

We characterized the embryonic expression pattern and mutant phenotypes of the Drosophila gene argos, which encodes a secreted protein with an epidermal growth factor motif. The argos null mutation caused an increase in chordotonal (Ch) organs in both the thoracic and the abdominal segments, whereas overexpression of the argos gene resulted in a decrease in these organs. We showed that the argos transcripts are expressed transiently in the cells surrounding the Ch organ precursor and that the gene rhomboid (rho), which is involved in the regulation of the number of Ch organs, acts epistatically to argos in this event. Our findings suggest that argos plays a role in Ch organ precursor formation and regulates the final number of Ch organs.

Abdomen↗
PubMed1985

1,25-Dihydroxyvitamin D3-induced calcium-binding protein: localization in organ-cultured embryonic chick duodenum.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) induces de novo biosynthesis of a specific calcium-binding protein (CaBP) in embryonic chick duodenum in organ culture. Using a highly sensitive and specific, peroxidase-antiperoxidase immunocytochemical procedure, 1,25(OH)2D3-induced CaBP in the organ-cultured duodenum was found only in the cytoplasm of absorptive cells, corresponding to its localization in rachitic chick duodenal cells after a single injection of 1,25(OH)2D3 in vivo. This observation, along with evidence correlating CaBP with calcium transport, strongly supports the use of the embryonic chick duodenal organ culture system as a physiologically relevant model of the vitamin D-dependent calcium absorptive mechanism.

Absorption↗
PubMed1993

Effect of wound healing and tissue transplantation on the navigation of axons in organ-cultured embryonic chick eyes.

Wound closure and repair of embryonic neuroepithelium were studied in organ-cultured embryonic retinae. Eyes from 3 to 4-day-old embryos were cultured after removing pieces of retinal tissue. During the subsequent 24 hours of incubation, the 150 to 200 microns wide holes in the retina closed completely. Histological studies showed that the wound closure was not accomplished by cell migration or cell proliferation, but by an approximation of the wound edges mediated by extracellular matrix fibrils of the vitreous body. The wound contraction facilitated the integration of transplants into the retinal neuroepithelium with a perfect alignment of the implants with the host at the vitreal surface. Within 24 hours, a continuous inner limiting membrane between transplant and host retina was established. The effect of wound healing and tissue transplantation on the navigation of optic axons in the retina was investigated. The wound contraction in the retina caused the optic axons near the lesion site to grow to the wound center, where the axons traversed the retina and formed a neuroma at the ventricular side, resembling the organization of axons at the optic disc. In the transplantation paradigm, axons from the host retina migrated into the transplant and vice versa. However, due to the wound contraction around the transplant, most axons grew into the interface between the transplant and host tissue.

Animals↗
PubMed1991

Hair cell differentiation in the developing chick cochlea and in embryonic cochlear organ culture.

We have defined a method for growing chick embryonic cochleae in organ culture that preserves many aspects of hair cell differentiation. Cochlear ducts were isolated from embryonic day 8 chicks, placed in organ culture, and incubated for 48 hours (to a point equivalent to embryonic day 10). The cultured ducts were then fixed and processed for scanning electron microscopy. As controls, cochlear ducts at embryonic days 8 and 10 were dissected and immediately fixed and processed for scanning electron microscopy. We chose this period to culture cochleae because at the corresponding time in vivo hair cells undergo a dynamic phase of differentiation. During this time, the number of stereocilia in the stereociliary bundle increases, and two to three rows of stereocilia nearest the kinocilium elongate, initiating the staircase pattern of the bundle. Also, the orientation of many hair cells shifts from nonpolarized at embryonic day 8 to polarized toward the inferior edge of the basilar papilla at embryonic day 10. Many of these aspects of hair cell differentiation proceed normally in organ culture. The appropriate distal-to-proximal gradients of hair cell density, apical surface area, and stereociliary number are preserved. Elongation of the 1-2 stereociliary rows next to the kinocilium continues, and more stereociliary bundles are oriented toward the inferior edge in cultured cochleae than in embryonic day 8 chicks. It appears that cochlear organ culture can serve as an effective method with which to study how hair cell differentiation is regulated.

Animals↗
PubMed2002

Reciprocal transmission of herpes simplex virus type 1 (HSV-1) between corneal epithelium and trigeminal neurites in an embryonic chick organ culture.

Reciprocal transmission between epithelia and sensory neurons of the peripheral nervous system is a crucial step in the life cycle of herpes simplex virus type 1 (HSV-1) and related alphaherpesviruses. In searching for an easy-to-perform and generally applicable experimental approach that enables the direct analysis of virus transfer between primary epithelial cells and sensory neurites, we investigated the spread of HSV-1 in a dual-chamber organ model comprising chick embryonic corneal epithelia and trigeminal sensory neurons. Embryonic chick corneal and trigeminal tissues were found to be permissive for productive infection with HSV-1. Our data show that HSV-1 efficiently enters neurites re-innervating the cornea and reaches the ganglion explant by retrograde axonal transport, with the first antigen-positive cells being detectable approximately 12 h postinfection. After direct infection of trigeminal tissues, the virus is transported by anterograde axonal transport to the corneal epithelium, causing a visible cytopathic effect approximately 48 h postinfection. These results suggest that the organ model presented in this study holds particular promise for the direct observation and molecular analysis of herpes simplex virus spread between primary epithelia and sensory neurons and that it may be an attractive alternative to current experimental approaches based on laboratory animals or human fetal tissues.

Animals↗
PubMed2003

Microbubble-enhanced sonoporation: efficient gene transduction technique for chick embryos.

The gene transduction technique is a useful method to study gene functions that underlie vertebrate embryogenesis. In this study, a new gene transduction technique is reported using microbubble-enhanced sonoporation (hereafter referred to as sonoporation) to achieve ectopic and transient gene expression for several embryonic organs including embryonic chick limb bud mesenchymes. The technique proposed in this study has the advantages of 1) relatively simple gene transduction procedures, and 2) efficient exogenous gene transduction and expression with lower damages to embryos. Green fluorescent protein (GFP) or LacZ was misexpressed in limb bud mesenchymes by sonoporation, with the introduced expression transiently detected in the injected sites. Most of the transduced chick embryos survived without showing significant embryonic abnormalities or cell death after sonoporation. To demonstrate its efficacy for assessing the effect of transient gene transduction, the Shh (sonic hedgehog) was transduced into the developing chick limb bud. The transduced limb bud displayed limb malformations including partial digit duplication. Advantages and possible future applications in relation to this method are discussed.

Animals↗
PubMed1993

Growth and morphogenesis of embryonic mouse organs on non-coated and extracellular matrix-coated Biopore membrane.

Embryonic mouse salivary glands, pancreata, and kidneys were isolated from embryos of appropriate gestational age by microdissection, and were cultured on Biopore membrane either non-coated or coated with type I collagen or Matrigel. As expected, use of Biopore membrane allowed high quality photomicroscopy of the living organs. In all organs extensive mesenchymal spreading was observed in the presence of type I collagen or Matrigel. However, differences were noted in the effects of extracellular matrix (ECM) coatings on epithelial growth and morphogenesis: salivary glands were minimally affected, pancreas morphogenesis was adversely affected, and kidney growth and branching apparently was enhanced. It is suggested that these differences in behaviour reflect differences in the strength of interactions between the mesenchymal cells and their surrounding endogenous matrix, compared to the exogenous ECM macromolecules. This method will be useful for culture of these and other embryonic organs. In particular, culture of kidney rudiments on ECM-coated Biopore offers a great improvement over previously used methods which do not allow morphogenesis to be followed in vitro.

Animals↗