These workers propose that the CL may be able to respond to extremely small amounts of CG but do not rule out the possibility that some other luteotropic or anti-luteolytic factor maintains the CL while CG rises to concentrations able to provide luteotropic support. Evidence from inhibin studies in marmosets supports the latter possibility, as there is a significant rise in inhibin production by Day 8 after ovulation in conception cycles compared to nonconception cycles. At this early stage of development, the production of CG by marmoset embryos is undetectable both in vitro and in vivo. It is possible that the embryo produces another factor for maternal recognition at preimplantation stages that causes this significant rise in inhibin production from the CL. Buy Advair Diskus Online
Alternatively, it is possible that parthenogenetic embryos do not produce bioactive CG, as there is some evidence that the gene for the p-subunit of CG may be imprinted and only expressed from the paternal chromosome. In humans, the p-subunit of CG is situated on chromosome 19 in an area syntenic to the distal part of mouse chromosome 7, which has some areas known to be imprinted.