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  • 1
    Electronic Resource
    Electronic Resource
    Lymphocyte formation in the thymus of the embryonic chickSupported by research grants HE-04061-05 (HEM) and 1 SO1 FR-05109-01 from the National Institutes of Health, Bethesda, Maryland. (1964)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 149 (1964), S. 191-215 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Embryonic thymus provides a distinct advantage over the definitive thymus because the earliest formation of lymphocyte and lymphocytic precursors can be observed in a relatively simple and uncomplicated situation. Special cytological techniques combined with light, phase, and electron microscopy have been performed in this investigation involving over 150 chick embryos between 5 and 18 days of embryonic development.Sequential cytological changes in the development of the thymus into an active lymphocytopoietic organ indicate that lymphoblasts develop by the gradual proliferation and transformation of “undifferentiated” epithelial cells comprising the primordial thymus. Lymphoblastic transformation begins on the seventh day of embryonic development in the chick and is characterized by increased cytoplasmic and nucleolar basophilia and chromatin condensation. “Undifferentiated” epithelial cells undergo two distinct lines of differentiation between the seventh and tenth days: into lymphoblasts and into stellate reticular-epithelial cells which constitute the organ parenchyma. All stages of lymphocytic maturation may be observed by 10-11 days as the thymus assumes a predominately lymphocytic character. Absence of lymphocytes or lymphocytic precursors in the connective tissue surrounding the embryonic thymus before and during the period of initial lymphoblastic transformation; presence of a continuous basement membrane surrounding the developing thymus; and absence of cells passing through this membrane during this phase of development indicate that the lymphocytic elements appearing in the embryonic thymus parenchyma are of epithelial rather than mesenchymal derivation. Although a contribution of mesenchymal elements to the lymphocytic population via vascular invasion and lobular formation in later stages of thymic development is unlikely, this question cannot be answered at this time. In spite of functional immunological distinctions between the lymphocytes of the chick thymus and bursa of Fabricius, the similarity of origin of the lymphocytic elements of these lympho-epithelial organs is apparent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091490204
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  • 2
    Electronic Resource
    Electronic Resource
    Lymphocytopoiesis in the bursa of FabriciusThis investigation was supported by research grant RG-5928 (A) from the National Institutes of Health, Bethesda 14, Md. (1959)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 104 (1959), S. 163-205 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001040202
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  • 3
    Electronic Resource
    Electronic Resource
    The epithelial origin of the lymphocytes in the thymus of the embryonic hamsterSupported by research grant HE-04061-06 (HEM) from the National Institutes of Health, Bethesda, Maryland. (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 152 (1965), S. 35-53 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Detailed cytological studies of serial sections have been performed on 85 golden hamster embryos ranging between 9 and 16 days (4-27 mm) of embryonic development.Sequential cytological changes in the development of the thymus of the hamster into an active lymphocytopoietic organ indicate that lymphoblasts develop by the gradual proliferation and transformation of “undifferentiated” epithelial cells comprising the primordial thymus. The “undifferentiated” epithelial cells undergo two distinct lines of differentiation during early development of the thymus: into lymphoblasts and into stellate reticular-epithelial cells which form the organ parenchyma. Transformation, both of lymphoblasts and reticular-epithelial cells begins during the eleventh day of development prior to the separation of the thymus and parathyroid.That the lymphoblastic and lymphocytic elements appearing in the embryonic thymus of the hamster are of epithelial rather than mesenchymal derivation is indicated by the following: (1) the absence of lymphocytes, lymphoblasts and hemopoietic activity in the connective tissue surrounding the embryonic thymus before and during the period of initial lymphoblastic formation; (2) the presence of a continuous basement membrane surrounding the developing thymus; (3) absence of cells passing through the basement membrane during this phase of development; (4) the absence of vascularity or vascular invasion of the thymus until after the appearance of lymphoblasts in the thymic parenchyma; (5) the demonstration of a sequential series of morphological transitions between “undifferentiated” epithelial cells and lymphoblasts and (6) the subsequent homoplastic proliferation and maturation of the lymphocytic elements from lymphoblasts in the developing thymus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091520106
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  • 4
    Electronic Resource
    Electronic Resource
    Vasculogenesis and erythropoiesis in the living yolk sac of the chick embryo a phase microscopic studySupported by research grant H-4061 from the National Institutes of Health, Bethesda, Md. and the Samuel J. Roessler Memorial Foundation, The Ohio State University. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 140 (1961), S. 29-43 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091400105
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of testosterone on the morphogenesis of the chick thymusSupported by Public Health Service Fellowship 5-fl-GM-20, 878-02 and research grant HE-04061-06(HEM) from the National Institutes of Health, Bethesda Maryland. (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 151 (1965), S. 11-15 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Because of the inhibitory effect of testosterone on lympho-epithelial nodule formation in the bursa of Fabricius, possibly through the suppression of alkaline phosphatase activity of the surrounding mesenchyme, there appears the possibility of a comparable inhibitory effect on the thymus.1. A single dose of one tenth milliliter (2.5 mg) of testosterone propionate in sesame oil (Schering) was injected into chick eggs between the first and fifth days of incubation, i.e., before and during the time of differentiation of the thymus from the epithelial primordia and before the appearance of lymphoblasts. The thymuses of 195 chicks including 50 controls were examined after 18 days of incubation; grossly and microscopically the thymus gland was relatively unaffected in all but a few chicks.Because the thymus appeared unaffected by testosterone as opposed to its complete inhibitory effect on the bursa of Fabricius; and because of the apparent relationship of testosterone-labile alkaline phosphatase to epithelial nodule formation in the bursa, further investigations were carried out on thymic differentiation and the possible role, if any, of alkaline phosphatase activity in the surrounding mesenchyme.2. Chick embryos between 5-10 days of incubation were fixed in 80% ethanol or absolute acetone, embedded in paraffin, serially sectioned and exposed to either Gomori's glycerophosphate or Burstone's naphthol AS-MX phosphate procedures for alkaline phosphatase activity. The mesenchyme surrounding the developing thymus showed either a negative or a negligible reaction for alkaline phosphatase activity following these procedures. In contrast, the thymic primordium did exhibit slight phosphatase activity which appeared to be localized in the reticular-epithelial cells.The difference in demonstrable alkaline phosphatase activity of the capsule of the thymus and of the subepithelial mesenchyme of the bursa of Fabricius suggests a fundamental difference in the differentiation of the two organs in the embryonic chick.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091510103
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  • 6
    Electronic Resource
    Electronic Resource
    Testosterone suppression of mesenchymal alkaline phosphatase activity and lympho-epithelial nodule formation in the bursa of fabricius in the embryonic chickSupported by research grant HE-04061-05 (HEM) from the National Institutes of Health, Bethesda, Md. (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 146 (1963), S. 23-27 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091460105
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  • 7
    Electronic Resource
    Electronic Resource
    A microscopic study of the adrenal of the Brown PelicanAided by a grant from The Comly Fund of The Ohio State University. (1951)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 109 (1951), S. 161-187 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091090204
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