size: 5036KB - Crocodile Specialist Group

90
If a feBale-based sex latio is desir€4 ar altertrative method would be the treatment of eggs
with estrogen. A variety of past studies have shown that injectiDg estrogen into develoPitrgiggs results
in or€riaD-differentiation regardless of iacubation temperature (reviewed by Ralnaud and Pieau, 19851
see also Gutzke and Bull, 1986; Crews et al., 1989) However, lhis metfiod sullers from a low
survivorship. A recent study has sho*Tr that toPicai applicadon of eskogen to tb€ egg shell-acts itr
similar fashion (Figure 7) and has neglgible nortality (Crews et al., 191)(Figure 8)-. Studies with the
leopard gecko indicate that such estrogen'induced females lay fertile eggs and exhibit normal nestbuilding
behavior.
We presently are investigating the mechadsm by which estrogen induces ovarian
differentiado;. Exp€riments ildicate that estrogen and tempelaturo act s)'dergistically on sex
dotermination, suggesting that they may act in a codnon Pathway (wibbels et al., 191)'
Male-producing
o'
Female'producing
I
Ficurc l- Eff.d of exo{coou cn'og'n (10us oI td'idio! 178 dislEd ir 5ul of 95% crhmor)
xul:Lr*.#:l;f ;l* li5"'":1':i?:i.il:g:'1x?:#',,1:lli;:tfi :",fl
'.I:
coiLdl ed m.dullarv rc3rn (f'od O.s
lger)