Document Detail


New insights on the mechanism of testis differentiation from the morphogenesis of experimentally induced testes in genetically female chick embryos.
MedLine Citation:
PMID:  2392999     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Embryonic testes grafted in the extraembryonic coelom of 3-day-old genetically female chick embryos may induce total and definitive reversal of gonadal sex differentiation. In this experimental condition, the left gonad becomes a testis instead of an ovary. This makes it possible to compare testicular and ovarian morphogenesis in animals having the same genetic sex and to discount what is due to differences in the genetic determination between male and female. The morphogenesis of such testes is marked by a disappearance of the cortical germinal epithelium. The medullary sex cords keep a narrow lumen instead of becoming large lacunae. The germ cells remain few in the sex cords and do not become meiotic. Furthermore, interstitial cell development is known to be very slow. As a consequence the gross size of the gonad is much smaller than that of an ovary. All these morphogenetic phenomena are unlike those observed during normal ovarian differentiation and evidence an inhibiting influence of the grafted testes. Since inhibition and masculinization are concomitant, inhibition appears to be the mechanism responsible for gonadal sex reversal. The extraembryonic situation of the grafted testes and their relation with the embryo only via the blood stream demonstrates the role of a secreted substance or substances still to be exactly identified. Previous data suggest that this could be the anti-Müllerian-hormone (AMH). Furthermore, previous and present results show that testis differentiation can be actively induced in a bird. This does not agree with the hypothesis that the gonads of the homogametic sex, i.e., the testes in birds, do not need any inducer in order to differentiate.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
R Maraud; O Vergnaud; M Rashedi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of anatomy     Volume:  188     ISSN:  0002-9106     ISO Abbreviation:  Am. J. Anat.     Publication Date:  1990 Aug 
Date Detail:
Created Date:  1990-10-01     Completed Date:  1990-10-01     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0376312     Medline TA:  Am J Anat     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  429-37     Citation Subset:  IM    
Affiliation:
Laboratoire d'Histologie-Embryologie, U.F.R. Médicale, Bordeaux, France.
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MeSH Terms
Descriptor/Qualifier:
Animals
Anti-Mullerian Hormone
Chick Embryo
Female
Glycoproteins*
Growth Inhibitors / physiology
Male
Mullerian Ducts / embryology,  physiology
Sex Differentiation / physiology*
Testicular Hormones / physiology
Testis / embryology*,  transplantation
Time Factors
Chemical
Reg. No./Substance:
0/Glycoproteins; 0/Growth Inhibitors; 0/Testicular Hormones; 80497-65-0/Anti-Mullerian Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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