[On the fine structure of the human embryonal vitreous body with special reference to its relationship to crystalline lens and retina].
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Humans↗
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[Prognostic factors in testicular seminoma and embryonal tumors with seminoma structure].
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Combined Modality Therapy↗
Development and structure of the extra-embryonic membranes of the ferret. A light microscopic and ultrastructural study.
Light and electron microscopic observations on the development and structure of the extra-embryonic membranes of the ferret are described. By day 16 of pregnancy trophoblastic villi consisting of a cytotrophoblastic core with a peripherally located phagocytic syncytiotrophoblast have penetrated deeply into the endometrium. During its invasion the syncytiotrophoblast removes endometrial glandular cells and some of the adjacent stromal tissue. The maternal blood vessels remain intact and eventually become surrounded by the syncytiotrophoblast. A marked hypertrophy of the maternal capillary endothelium then begine. By day 28 the maternal capillary endothelial cells attain their maximum height. The cytoplasm of these cells contains numerous cisternae of rough endoplasmic reticulum and a well-developed Golgi apparatus, features which are typical of protein-secreting cells. The maternal blood vessels are separated from the syncytiotrophoblast by a thick layer of amorphous material which stains positively with PAS. Alcian blue staining in the presence of critical concentrations of magnesium chloride indicates the presence of both sulphated and carboxylated acid mucopolysaccharides. It may be that the amorphous material contributes significantly to the nutritional requirements of the developing fetus. Invaginations of the syncytiotrophoblast plasma membrane facing this amorphous layer are often seen. Coated vesicles and substances in contact with the outer surface of the membrane are therefore likely to be endocytozed. The acid phosphatase in the syncytiotrophoblast is consistent with the presence of lysosomes and catabolic function. Regions of paraplacental cellular trophoblast which lie in close association with the endometrium, but do not penetrate it, appear to specialize in endocytosis. The haemophagus organ, which is located at the antimesometrial pole, is the site of rupture of maternal blood vessels, and the extravasated blood lies in close association with the chorio-allantoic membrane. The maternal blood cells ingested by the trophoblast in this area are presumably an important source of iron for the embryo. The cellular trophoblast in the paraplacental regions is well equipped with hydrolytic enzymes, as shown by histochemical tests for acid phosphatase. It seems likely that these regions are concerned with embryotrophic endocytotic nutrition supplementing endothelio-chorial nutrition.
Animals↗
The ultrastructure of mouse embryonic stem cells.
The fine structure of mouse embryonic stem (ES) cell colonies was analysed by scanning and transmission electron microscopy. Most of the ES cells had numerous microvilli of different lengths. Coated pits and vesicles were also seen along areas of the peripheral cytoplasm and plasma membranes. Junctional complexes including gap junctions were observed between adjacent ES cells. These cells had Golgi complexes, spherical to oval mitochondria, lysosomes and typical centrioles, microfilaments and microtubules and large nuclei containing reticulated nucleoli. These results are consistent with the ultrastructural features of undifferentiated cells.
Animals↗
Relationship of steroid structure to induction of chymotrypsinogen in embryonic chick pancreas in vitro.
The effect of steroid structure on induction of chymotrypsinogen in embryonic chick pancreas was examined in vitro. In order of decreasing potency cortisol, corticosterone, and 21-deoxycortisol are classified as optimal inducers, whereas 11beta-hydroxyprogesterone, 11-deoxycortisol, cortisone, 11-deoxycorticosterone and 17-alpha-hydroxyprogesterone are classified as suboptimal inducers. Progesterone was inactive. It is concluded that the relative importance of the steroid hydroxyl groups for activity is 11beta greater than 21 greater than 17 alpha, and that their effect is cumulative.
Adrenal Cortex Hormones↗
Activity-regulated, cytoskeleton-associated protein (Arc) is essential for visceral endoderm organization during early embryogenesis.
Activity-regulated, cytoskeleton-associated protein (Arc) was first identified as an immediate-early gene regulated by synaptic activity. We have studied its functional role in vivo using a gene-targeting approach. We found that Arc is encoded by a single exon, and Arc mRNA is ubiquitously expressed in early mouse embryos. Homozygous Arc mutants are severely growth-retarded, fail to gastrulate and subsequently die before day 8.5 of embryogenesis. Further analysis revealed severe disorganization of visceral endoderm formation, and total separation and ectopic location of embryonic and extraembryonic structure. These findings demonstrate that Arc function is essential for early embryo development and patterning in mice, and support the hypothesis that signaling from visceral endoderm is essential for normal patterning of the extraembryonic and embryonic structure.
Animals↗
Intrauterine ultrasonographic assessments of embryonic development.
OBJECTIVE: Our purpose was to describe embryonal anatomic structures by use of intrauterine ultrasonography with a 20 MHz flexible catheter-based, high-resolution, real-time miniature transducer. STUDY DESIGN: Thirty-four women about to undergo therapeutic abortion from 7 to 9.9 weeks' gestation were studied with specially developed catheter-based, high-resolution, real-time miniature (2.4 mm outer diameter) ultrasonography transducer (20 MHz). A percentage of anatomic structures visualized at each gestational age is presented. RESULTS: The number and the clarity of structures increased from 7 to 8 weeks of gestation; however, the image quality was degraded because of the increasing fetal size at 9 weeks. At 8 weeks secondary brain vesicles, spine, midgut herniation, liver, upper and lower limb buds, and sacral tail were visualized in all fetuses. The four-chamber view was first identified at 8 weeks, as were fingers or toes. The stomach was first noted at 9 weeks. The umbilical cord cyst was visualized in 8% of embryos at 7 weeks' gestation and in 29% of embryos at 8 weeks. One cystic hygroma was diagnosed at 8 weeks 5 days. CONCLUSION: Intrauterine ultrasonography provides information on the visualization of anatomic structures of the embryo. In this limited series one embryonic malformation was demonstrated, and thus there is a potential for its use in the detection of malformations. These results suggest that intrauterine ultrasonography has the potential to be a supplement to transvaginal ultrasonography during the first trimester in high-risk pregnancies.
Brain↗
[Structural differentiation of dissociated skeletal embryonal myocytes of frog under conditions of cell culture].
The development of membrane structures, providing E-C coupling, and the contractile apparatus organization were investigated in frog skeletal myocytes cultured for 1 to 10 days in conditions preventing both myocyte division and fusion. Ruthenium red was used to determine the membranous structures being in contact with the extracellular environment. The marked membrane structures (vesicles and short tubules) appeared to be near the cell membrane on the first days of culturing. The increase in the ratio of the surface area of all internal membranous structures, marked by Ruthenium red, to the external membrane area with aging was proven by morphometric calculations, that means a progressive development. Contractile filaments were found near the cell membrane on the first days of development. Bundles of filaments with initial signs of sarcomere organization were observed on the 3rd-4th days, and myofibrils with highly organized sarcomeres occupied the main part of the sarcoplasm on the 6th day of culturing. The triads appeared also on the sixth day, being regularly inserted into the sarcomere structure. Degenerative signs in the myocytes (sarcomere disorganization and T-tubule swelling) were observed on the 8-10th days, but the area occupied by contractile elements was increased. These results show that the myocyte fusion into myotubules is not a necessary condition for either sarcomere formation, or the formation of all membranous structures providing the E-C coupling.
Animals↗
Embryonic stem cells form glandular structures and express surfactant protein C following culture with dissociated fetal respiratory tissue.
Mouse embryonic stem cells (MESCs) are pluripotent, theoretically immortal cells derived from the inner cell mass of developing blastocysts. The respiratory epithelium develops from the primitive foregut endoderm as a result of inductive morphogenetic interactions with the surrounding visceral mesoderm. After dissociation of the explanted fetal lung into single cells, these morphogenetic signaling pathways instruct reconstitution of the developing lung according to a process known as organotypic regeneration. Data presented here demonstrate that such fetal lung morphogenetic cues induce MESC derivatives to incorporate into the reforming pseudoglandular-like tubular ducts, display pan-keratin and surfactant protein C (Sftpc) immunoreactivity, and express Sftpc transcripts while displaying a normal diploid karyotype in coculture. The Sftpc inductive capacity of dissociated fetal lung tissue shows stage specificity with 24% of all MESC derivatives displaying Sftpc immunoreactivity after coculture with embryonic day 11.5 (E11.5) lung buds compared with 6% and 0.02% following coculture with E12.5 and E13.5 lung buds, respectively. MESC derivative Sftpc immunoreactivity follows a spatial and temporal specific maturation profile with an initially ubiquitous cellular Sftpc immunostaining pattern becoming apically polarized with time. Directing differentiation of MESCs into respiratory lineages has important implications for cell replacement therapeutics aimed at treating respiratory-specific diseases such as cystic fibrosis and idiopathic pulmonary fibrosis.
Animals↗
Two components from eye tissue that differentially stimulate the growth and development of ciliary ganglion neurons in cell culture.
Survival and development of chick ciliary ganglion neurons in vivo appear to depend on information from the embryonic eye structure that contains the postsynaptic targets of the neurons. We have tested embryonic eye extracts on ciliary ganglion neurons in dissociated cell culture for stimulation of growth and development. Control conditions were chosen that permitted the long term maintenance of the neurons in the absence of tissue extracts of conditioned medium. The conditions included coating the culture substratum with fibroblast material and increasing the K+ concentration in the culture medium to 25 mM. Neurons survived for at least 3 weeks in control conditions. Two major components were resolved in eye extracts that stimulated growth and development of the neurons above the basal levels obtained with control conditions. One component, with an apparent molecular weight of about 2 X 10(4) by gel filtration analysis, stimulated neuronal growth without increasing the levels of choline acetyltransferase activity per neuron. The second component, with an apparent molecular weight of about 5 X 10(4), increased development of choline acetyltransferase levels per neuron but had no effect on neuronal growth. Both components were effective in normal K+ as well as 25 mM K+. These components may represent mechanisms by which the postsynaptic target tissue acts in vivo to direct the growth and development of ciliary ganglion neurons.
Animals↗
[Changes in the ultra-fine structure of capillaries of the embryonic brain in the presence of schizophrenia in the mother].
The report is concerned with a study of fine structures of brain capillaries in 9 embryos received during medical abortions from schizophrenic mothers. The authors established some traits in the ultrastructure of endothelial cells in most of the studied cases--an increase of the surface of endothelial cells at the expense of a tortuosity of their plasmatic membranes and a formation of growths, vacuolization of the cytoplasma. There were also some changes in the structure of basal membranes. In 2 cases there were also peculiar pathological changes in the vascular endothelium: granules of an unknown nature in the endothelial cells and a focal lysis of the plasmatic membranes of endothelial cells.
Brain↗
Liver development in the rat and in man during the embryonic period (Carnegie stages 11-23).
Hepatic structures appearing during embryonic Carnegie stages 11-23 were analyzed and compared in OFA-IOPS rat and human embryos. The group of rats--crown-rump length (CRL) 2-16 mm, 10-16 days postcoitus--was composed of 127 specimens (52 of stages 11-12, 55 of stages 13-19, and 20 of stages 20-23), the human group of 9 embryos at stages 14-23--CRL 5-31 mm, age 32-57 days--and human stages 11-13 were described according to former literature. The specimens were subjected to serial histological sections with graphic reconstructions. In both series, stage 11 was characterized by hepatic diverticulum development, stage 12 and thereafter by cellular differentiation (septum transversum giving the liver stroma and hepatic diverticulum the hepatic trabeculae), and stage 13 by epithelial cord proliferation enmeshing stromal capillaries. From stage 14, the hepatic gland and its vascular channels presented considerable enlargement while hematopoietic function appeared. From this stage, the development of cystic primordium, never present in rat, was constant in man. At stage 18, after a period of obturation due to epithelial proliferation, the bile ducts became reorganized and ensured the continuity between liver cells and gut. From stages 18 to 23, biliary ductules developed in periportal connective tissue producing ductal plates that received biliary capillaries. Except for gallbladder, similarity and presence of the same hepatic structures in man and rat during the embryonic period stages 11-23 permit us to consider the rat as a good experimental model for liver development, for example, in studies on teratology and congenital anomalies.
Animals↗
Structure and function of prothoracic glands and oenocytes in embryos and last larval instars of Oncopeltus fasciatus Dallas (Insecta, Heteroptera).
1. Active prothoracic glands and oenocytes of last larval stage are both characteristized by well-developed smooth and rough endoplasmic reticulum (ER). Prothoracic glands also show plasma membrane infoldings, but not oenocytes which contain a large number of pleomorphic vesicles. 2. The fine structure of embryonic oenocytes corresponds after blastokinesis with that of active larval and adult cells. Thus, an activity in the late embryo can be assumed. Embryonic prothoracic glands reveal no signs of activity: smooth and rough ER are absent. The subcellular structure resembles that of organ anlagen, i.e. not yet fully differentiated tissue. Hormone synthesis is not likely. 3. Ecdysone titer was determined throughout embryonic development and in mature adults. Although prothoracic glands break down during adult ecdysis, imagines contain in the Calliphora-bioassay active factors: females 0.9 CU/g and males 0.5 CU/g. As sites of synthesis the oenocytes are suggested. 4. A relatively high ecdysone titer of 7 CU/g is measured in newly deposited eggs. The hormone is presumably of maternal origin. Subsequent to blastokinesis the hormone content increases dramatically up to about 180 CU/g, apparently due to endocrine function of the embryo. Oenocytes are proposed as the source of ecdysone during late embryonic development. 5. The function of ecdysone during early and advanced embryogenesis, especially in view of "embryonic molts", is discussed.
Animals↗
[Histogenesis of human embryonal cancer of the testis].
Complex morphological study of 45 germ cell tumors of the testis revealed two types of histological structure of embryonal carcinoma. Tumour histostructure was related to the ultrastructural features of cells (I-IV types) forming them. The data obtained indicate that the process of differentiation of these tumours resembles initial stages of embryogenesis (morula, blastula, egg cylinder). Embryonal carcinoma cells appeared to be tumor stem cells in the development of teratoma, chorionepithelioma, yolk sac tumour.
Embryonal Carcinoma Stem Cells↗
Fine structure of Plasmodium gallinaceum in embryonic and neonate chicks.
The erythrocytic stages of Plasmdoium gallinaceum in chicken embryos injected with parasited blood either from a syringe-passaged infection in chickens or from a chicken infected with sporozoites were characterized by abnormal structure. Particularly evident were large, unstained vacuoles within the cytoplasm; these occurred with greatest frequency in schizonts. The presence of myelin bodies within these vacuoles was revealed by transmission electron microscopy; abnormal cytokinesis and aberrant merozoites provided additional evidence of the parasite's inability to develop naturally within the milieu of the embryonic erythrocytes. Fifty-five passages were necessary to restore normal structure of the parasites in embryos, while only 5 passages were required for such restoration in neonate chicks. The probable adaptation of the parasite to the proportions of hemoglobin of the adult chicken may be responsible for the abnormal growth in the immature host.
Animals↗
Synovial nature of pathologic periarticular structures, including subcutaneous nodules. descent from embryonic arthrogenic fibroblasts: a hypothesis.
In the embryo the periarticular fibroblasts were the producers of the greater part of the joint they surround in later life, as well as of the tendon sheaths and bursae. It is postulated that adult fibroblasts have retained atavistic arthrogenic properties, and may react to traumatizing, inflammatory and oncogenic stimuli by forming periarticular joint-like structures: "arthromas" such as ganglia, meniscal cysts, synovial cysts, synovial sarcoma and subcutaneous nodules. The arthroid nature of these growths manifests itself by the presence of a central cavity, which can be identified as a synovial cavity by histologic, histochemical and electron-microscopic methods. In case of affection of the joint all of these adnexa may be involved. A resemblance of these structures to embryonic joint tissues has been noted for years. The nature of the subcutaneous nodule is discussed at some length. It may contain one or more synovial clefts; synovial elements may be found in its centre by histochemistry and electron-microscopy. Recent and personal findings shed a new light on palisading cells, which may be fibroblasts, having taken up again their embryonic task as synovioblasts. From periarticular fibroblasts thus three kinds of tumors may arise; benign (ganglia, cysts, subcutaneous nodules), malignant (synovial sarcoma) and "semi-malignant" (pannus in rheumatoid arthritis).
Arthritis, Rheumatoid↗
Cadherin expression by embryonic divisions and derived gray matter structures in the telencephalon of the chicken.
The expression of three cadherins (cadherin-6B, cadherin-7, and R-cadherin) was studied by immunohistochemistry in the telencephalon of chicken embryos at intermediate stages of development (11 and 15 days of incubation). Expression patterns were related to cytoarchitecture and to previously published data on functional connections and on the expression of gene regulatory proteins. Our results indicate that, like in other regions of the embryonic chicken brain, the expression of each cadherin is restricted to parts of embryonic divisions as well as to particular nuclei, areas or their subdivisions. The expression patterns are largely complementary with partial overlap. The regional expression of the cadherins respects the boundary between the pallium and the subpallium as well as between various pallial and subpallial subdivisions. Novel subdivisions were found in several telencephalic areas. For example, subjacent to the hyperstriatum, the neostriatum contains multiple islands of cells with a profile of cadherin expression that differs from the surrounding matrix ("island fields"). Moreover, the expression of each cadherin is apparently associated with parts of intratelencephalic neural circuits and of thalamopallial and basal ganglia pathways. These results support a role for cadherins in the aggregation and differentiation of gray matter structures within embryonic brain divisions. The cadherin immunostaining patterns are interpreted in the context of a recently proposed divisional scheme of the avian pallium that postulates medial, dorsal, lateral, and ventral divisions as complete radial histogenetic units (Puelles et al. [2000]).
Aging↗
Testicular cell conditioned medium supports differentiation of embryonic stem cells into ovarian structures containing oocytes.
Previous reports and the current study have found that germ cell precursor cells appear in embryoid bodies (EBs) formed from mouse embryonic stem cells as identified by positive expression of specific germ cell markers such as Oct-3/4, Mvh, c-kit, Stella, and DAZL. We hypothesized that if exposed to appropriate growth factors, the germ cell precursor cells within the EBs would differentiate into gametes. The source for growth factors used in the present study is conditioned medium collected from testicular cell cultures prepared from the testes of newborn males. Testes at this stage of development contain most growth factors required for the transformation of germ stem cells into differentiated gametes. When EBs were cultured in the conditioned medium, they developed into ovarian structures, which contained putative oocytes. The oocytes were surrounded by one to two layers of flattened cells and did not have a visible zona pellucida. However, oocyte-specific markers such as Fig-alpha and ZP3 were found expressed by the ovarian structures. The production of oocytes using this method is repeatable and reliable and may be applicable to other mammalian species, including the human.
Animals↗