Estradiol secretion by the ovarian tissue, in response to hypophyseal stimulation, during ontogenesis of the bullfrog.
Ovaries of tadpoles, froglets, young frogs, and mature frogs of Rana catesbeiana were cut into small pieces. They were incubated for 6 hr in Krebs-Ringer bicarbonate buffer as controls. Another series of ovaries of the same developmental stages were incubated with pituitary extracts in the buffer as experimentals. Media were then analyzed for estradiol secretion by radioimmunoassay. The results showed that estradiol secretion by tadpole ovaries during development was not affected by the addition of pituitary extracts of mature frogs in the media at any stage while those of young and mature frogs with pituitary extracts secreted more estradiol than those without. These findings indicate that tadpole ovaries are unresponsive to pituitary agents to produce estradiol while frog ovaries are dependent on some pituitary hormones to synthesize estradiol. Thus frog ovaries acquire dependence on the pituitary agent only after metamorphosis.
Hsu
C Y
CY
Department of Biomorphics, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Yu
N W
NW
Chang
L T
LT
Ku
H H
HH
Lu
M H
MH
D000818:Animals; D004958:Estradiol / Q000032:analysis / Q000378:metabolism*; D005260:Female; D010053:Ovary / Q000378:metabolism / Q000502:physiology*; D010902:Pituitary Gland / Q000502:physiology*; D011892:Rana catesbeiana / Q000254:growth & development / Q000502:physiology*; D014020:Tissue Extracts / Q000494:pharmacology*
D014020:Tissue Extracts; D004958:Estradiol