Luteal phase ovarian oestrogen is not essential for implantation and maintenance of pregnancy from surrogate embryo transfer in the rhesus monkey

Abstract

The aim of this study was to investigate whether luteal phase ovarian oestrogen is required for blastocyst implantation and pregnancy maintenance in the rhesus monkey. Preimplantation embryos were retrieved from naturally ovulated, mated embryo donor monkeys. In group I, developmentally normal, age- and stage-matched embryos were transferred to recipient monkeys showing naturally synchronized ovulatory cycles. Immediately prior to embryo transfer, recipients were subjected to bilateral ovariectomy, and following transfer they were treated with i.m. injections of either progesterone (group Ia, n = 4), or oestradiol + progesterone (group Ib, n = 2). Recipient monkeys of group Ic (n = 4) were subjected to sham ovariectomy and vehicle injection. In group Ia, progesterone supplementation alone led to three pregnancies and live births. In group Ib, there was one live birth. In the control group Ic, four transfers resulted in two live births and one abortion on cycle day 58. Analysis of serum progesterone and oestradiol profiles showed that oestradiol had declined to undetectable levels within 3-5 days after ovariectomy in group Ia recipients, and the area under the curve of serum oestrogen concentrations during the peri-implantation period (days 10-20 after ovulation) were less (P < 0.001) in group Ia compared with group Ic. There were no changes in the area under the curve among serum progesterone concentrations in all the subgroups. In group II, long-term ovariectomized embryo recipients (n = 4) were primed with oestradiol till cycle day 11 of simulated transfer cycle, and received progesterone treatment from cycle day 10 till the end of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Endometrial Receptivity and Human Embryo Implantation

“…18 Animal models also prove this concept. 19 However, progesterone is essential for blastocyst implantation and has also been well proved by (i) neutralization of circulating progesterone [20][21][22][23] by administration of specific antibodies; (ii) by inhibiting the biosynthesis of progesterone or indirectly by inhibiting stimulation of these cells by hormones, and (iii) by interfering with the action of progesterone at target organ level through the use of progesterone receptor blockers or antiprogestogens. [24][25][26] Collectively, it appears that progesterone is essential for endometrium to attain the receptive stage, blastocyst implantation, and maintenance of pregnancy, and that mid-luteal-phase ovarian estrogen is not essential for blastocyst implantation and maintenance of pregnancy.…”

Leukemia inhibitory factor ligand-receptor signaling is important for uterine receptivity and implantation in golden hamsters (Mesocricetus auratus)

“…In contrast, dating of the time of ovulation, chronological development of the secretory endometrium, and the timing of implantation cannot be accurately predicted in humans. It has been demonstrated that in the majority of species, such as the hamster, rabbit, pig, guinea pig, monkey, and human, luteal estrogen is not required to initiate the process of implantation (Deanesly 1960, Prasad et al 1960, Orsini & Meyer 1962, Harper et al 1969, Meyer et al 1969, Perry et al 1973, George & Wilson 1978, Heap et al 1981, Hoversland et al 1982, Ghosh et al 1994, Zegers-Hochschild & Altieri 1995, Wang et al 2002, 2004, Zhang & Paria 2006. A comprehensive study has not been done on the relative involvement and functions of uterine Lif in species where implantation is dependent on ovarian P 4 , but not E. Thus, the present experiments were undertaken to study the expression of Lif and its receptors during the periimplantation period and their hormonal and embryonic regulation in hamsters.…”

As the world grows: contraception in the 21st century

“…The search for agents that work postovulation up to and including blastocyst attachment to the endometrium has been vigorously pursued for over 50 years. However, the animal models used in most studies were rats or mice, which eventually proved to be unsuitable, since they require ovarian estrogen to initiate the process of implantation, whereas primates do not (125,126). Hence, selective estrogen receptor modulators (SERMs) will not be contraceptives in women.…”