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  • 1
    Electronic Resource
    Electronic Resource
    Oogenesis and ovarian development in the prenatal pigFrom a thesis submitted by J. L. Black to the Graduate Council, The University of Tennessee, in partial fulfillment of the requirement for the degree of Doctor of Philosophy.This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville. (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 161 (1968), S. 45-55 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Gametogenesis and ovarian development were examined by means of histologic, cytologic and radioisotopic techniques in porcine ovaries of ages ranging from 13 days post coitum (PC) to birth (114 days PC). Limited observations were made in postnatal ovaries (birth to 130 days post partum).Primordial germ cells were noted at 18 days PC in the region of the germinal ridge (border of mesonephros) seven days prior to its formation (24-25 days).Meiosis began as early as day 40 in some cases and was a characteristic of most ovaries by day 50.Diplotene, the resting stage of porcine oocytes, first appeared at 50 days PC and 99% of all germ cells were at diplotene by 20 days post partum. Both the paucity of oogonia and absence of oogonial mitoses at day 100 PC signaled the end of oogenesis.The number of germ cells increased dramatically from the 5,000 seen at 20 days PC to a peak of 1,100,000 at 50 days. Subsequently, germinal mitotic activity decreased and necrosis of germ cells concurrently increased, resulting in a population of approximately 500,000 germ cells at birth.The injection of tritiated thymidine into fetuses of varying ages revealed that in the pig the definitive stock of oocytes arises from the prenatal period prior to day 100 with the 70-day PC-period being the major contributor.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091610105
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Medullary osteogenesis with platinum cathodes (1985)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 3 (1985), S. 125-136 
    Details
    ISSN: 0736-0266
    Keywords: Electrical stimulation ; Osteogenesis ; Platinum ; Stainless steel ; Electrode materials ; Microtrauma ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Studies of electrical stimulation of osteogenesis with stainless steel electrodes have previously established a dose-response relationship between current and bone growth. Examination of the effect of different geometric current densities resulted in the conclusion that very little electrode surface area was involved in stimulation and led to the design of a multiport “distributive” cathode. A series of experiments were performed to extend these results to wire and multiport platinum electrodes. As before, a current-bone growth dose-response relationship was found. Peak bone growth was greater than for stainless steel. However, peak bone growth occurred at 2.0 μA (versus 20 μA for stainless steel). Correlation studies suggest that small changes in cathodic potential affect bone growth more than similar size changes in current. Finally, the generally benign local host response to platinum suggests that platinum may be a suitable materials for chronic indwelling anodes for stimulation of osteogenesis.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100030201
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  • 3
    Electronic Resource
    Electronic Resource
    Temporal course of bone formation in response to constant direct current stimulation (1985)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 3 (1985), S. 137-139 
    Details
    ISSN: 0736-0266
    Keywords: Electrical osteogenesis ; Direct current ; Stainless steel electrodes ; Medulary canal ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Reactive, post-traumatic bone formation in response to intramedullary insertion of a polytetrafluorethylene-coated, 28 gauge stainless steel wire was compared with the sequential bone formation seen in response to an indentical intramedullary stainless steel cathode delivering 20 μA constant direct current. Animals were studied at days 1, 2, 3, 4, 5, 7, 9, 11, 14, 17, and 21 after wire insertion. Point count analysis revealed progressive bone formation beginning as early as day 3 on the constant direct current-stimulated side, progressing steadily through day 21. Control tibia, however, began to show bone formation on day 5 with peaking at day 9 and subsequent bone resorption. The osteogenic response at the 20 μA cathode was statistically elevated above that seen at the control on days 11, 17, and 21.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100030202
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    Paper (German National Licenses)
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