Persistence after hypothalamectomy of a tamoxifen-like effect in the ovary of quail embryos exposed cyclically in ovo to low incubation temperatures.
Three days old quail embryos were hypothalamectomized in ovo by the decapitation technique according to Callebaut (1993). Half of these embryos was exposed to day cyclically repeated prolonged low subnormal incubation temperatures (25 degrees C). The other half of these decapitated embryos was normally continuously incubated. As is the case for not decapitated embryos the ovaries of the first group presented a tamoxifen like effect: cortical rim atrophy with proportional hypertrophy of the medulla and a pronounced decrease in the number of oogonia and oocytes. By contrast the ovaries of the second group of decapitated embryos presented a normal aspect without sterilization of the ovigerous sex cords. It was concluded that: 1. the hypophysis, the hypothalamus or other prosencephalic tissues play no intermediary role in the establishment of a tamoxifen like effect in the ovary; 2. the early embryonic development of the quail ovary during the considered period takes place without the intervention of the hypothalamus.
Callebaut
M
M
Laboratory of Human Anatomy and Embryology, RUCA, Antwerpen, Belgium.
D'Herde
K
K
Van Nassauw
L
L
Harrisson
F
F
D000818:Animals; D002940:Circadian Rhythm; D003370:Coturnix / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000187:drug effects; D005260:Female; D007031:Hypothalamus / Q000502:physiology*; D010053:Ovary / Q000187:drug effects*; D013629:Tamoxifen / Q000494:pharmacology*; D013696:Temperature
D013629:Tamoxifen