Medically Assisted Conception An Agenda for Research (1989) / Chapter Skim
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Intragonadal Control of Testis Function
Intragonadal Control of Testis Function
Pages 191-210
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From page 191... ...
Cellular interactions are not restricted to the somatic cells of this organ as there is substantial morphological and physiological evidence for the interaction of germ cells with one another and with the Sertoli cells. However, we know much less about the interactions involving germ cells than we know about the interactions restricted to the somatic cell types.
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From page 192... ...
13. A cell enters the cell cycle from the Go state in response to specific growth factors called competence factors, two of which are platlet derived growth factor (PDGF)
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From page 193... ...
Thus, the replication of Sertoli cells and Leydig cells appear to exhibit opposite patterns, with numbers of Leydig cells increasing rapidly only after the end of Sertoli cell proliferation. An examination of the source and biological activities of some of the growth factors and hormones in the testis lead to the hypothesis that the replication of Leydig cells and Sertoli cells are related processes.
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From page 194... ...
in of the development of germ cells in vitro when those cells within intact segments of seminiferous tubules. Those reported that late meiotic cells would complete meiosis and , ~ bound to the Sertoli cells within the tubule.
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From page 195... ...
The process of spermatogenesis and the organization of the seminiferous epithelium. While it is established that germ cells and Sertoli cells can interact, we do not know how these interactions regulate the diverse cellular events required for spermatogenesis.
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From page 196... ...
We assumed that Sertoli cells products which regulated specific steps in the development of spermatogenic cells would be secreted at a time when these factors were required by those germ cells. Based on this assumption, it followed that such factors would be secreted at specific stages of the cycle of the seminiferous epithelium.
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From page 197... ...
This analysis revealed that the proteins recovered from the medium changed dramatically with progression of the cycle of the seminiferous epithelium and suggested that there were profound changes in the synthesis of Sertoli cell secretory products with progression of the cycle (637. Of particular note was an extremely heterogeneous protein or family of proteins we called Cyclic protein 2 or CP-2 which had a mean pI of 5.5 and mean molecular size of 37,000.
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From page 198... ...
We have seen that changes in the secretion or concentration of specific growth factors may regulate the growth of the Leydig cell and Sertoli cell population. We have seen that all forms of cell-cell communication are active in the seminiferous epithelium and have argued that the control of spermatogenesis must be a precise but complex process .
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From page 199... ...
Regulation of the Balb/c-3T3 cell cycle-effects of growth factors..J. Supremolecular Structure 13:489-499.
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From page 200... ...
Rat Sertoli cells secrete a growth factor that blocks epidermal growth factor (EGF) binding to its receptor.
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From page 201... ...
Orth, J.M., 1986. FSH-induced Sertoli cell proliferation in the developing rat is modified by beta endorphin produced in the testis.
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From page 202... ...
Insulin-like growth factor I (IGF-I) receptors on Sertoli cells from immature rats and age-dependent testicular binding of TGF-I and insulin.
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From page 203... ...
Jegou, 1988. In vitro effects of germ cells on the secretory activity of Sertoli cells recovered from rats of different ages.
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From page 204... ...
Isolation of cyclic protein-2 from rat seminiferous tubule fluid and Sertoli cell culture medium.
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From page 205... ...
18 \ i 1 s~ ~ _ — ~ \ ~ ~ ~ A- ~ -30 '0 ED 80 40 80 60 ~ ~~ ~~) Replication of Sertoli cells and Leydig cells during prepUbert~l development of the rat testis.
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From page 206... ...
RNA synthesis by the spermatogenic cells impressed as 3~-uridine incorporated by the germ cells during a two hour period. DNA `;ynthesi'; by the permatogenic cells is expressed as 3~-thymidine incorporated by the germ cells during a two hour period.
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From page 207... ...
Data are expressed as the amount of ABP secreted in 24 hours per microgram of Sertoli cell DNA. Data are from reference 51.
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From page 208... ...
Purification of CP-2. CP-2 was purified fray seminiferous tubule fluid by a four step chromatographic procedure.
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From page 209... ...
Sertoli cell Soo~atometin C Progreasion factor 13,14 EGF-like factor Progression factor 15,16 Inhibin Related to 'hormones' which Induce differentiation 17,18 Seminlferous-growth Unique to testis ~ r factor 19-21 Interleukin I Suppresses entry of~cells , ,,, into Go 22 .
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From page 210... ...
.... 5 cm of seminiferous tubules were cultured for 1 hr (synthesis)
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