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A. B. Gilbert, M. F. Davidson and J. W. Wells

Summary. Surgical removal of the granulosa cells, leaving the remainder of the postovulatory follicle (POF) intact (including the thecal interstitial cells), resulted in delays of oviposition of about 19 h; similar delays were obtained when the granulosa was left in situ but was damaged by the insertion of a silicone disc into the POF. The insertion of wax balls resulted in delays of 3–4 h but the granulosa appeared to be normal. It is concluded that the integrity of the granulosa is important for normal oviposition.

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Urinary gonadotrophins have frequently been measured during the menstrual cycle (see Evans & Simpson, 1950; Loraine & Schmidt-Elmendorff, 1963). The most commonly applied method of assay has been that depending on the uterine response in immature mice, which measures both follicle-stimulating hormone (fsh) and luteinizing hormone (lh) (Brown & Billewicz, 1962), and this might explain why some workers have found that it fails to provide evidence of a meaningful relationship between pituitary and ovarian function (Loraine & Schmidt-Elmendorff, 1963). Preliminary experiments (Brown, Wells & Cunningham, 1964) have suggested that the method of Cunningham (1962) might be useful in demonstrating significant changes in pituitary gonadotrophic function if such occur. The method depends on the induction of ovulation in immature mice, and
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In a previous study of the effect of an oral contraceptive (Brown, Wells & Cunningham, 1964), urinary gonadotrophin was measured by its ability to induce ovulation in mice (Cunningham, 1962; Wells, Khosla & Brown, 1964). This method of assay, though not specific for luteinizing hormone, was considered appropriate for investigating the action of drugs which prevent ovulation. The study of two women, one through two complete menstrual cycles and the other through three, showed that treatment with a combination of norethynodrel and mestranol abolished the mid-cycle peak of gonadotrophin excretion. Before further study of the mode of action of oral contraceptives, more experience was gained with the pattern of excretion of gonadotrophin during the normal menstrual cycle measured with this assay

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R. D. Geisert, T. C. Fox, G. L. Morgan, M. E. Wells, R. P. Wettemann and M. T. Zavy

Summary. Treatment of recipient cows with 100 mg of progesterone daily from Days 1 to 5 of the oestrous cycle increased plasma progesterone compared with vehicle-treated recipients. Embryo transfer to progesterone-treated recipients which showed oestrus 72 h after the donor cows resulted in pregnancy rates at Day 35 similar to those of synchronous (±12 h) recipients (42 vs. 50%). Only 1 of 22 (4·8%) asynchronous (−72 h) vehicle-treated recipients established pregnancy. Similar treatments of cyclic cows with progesterone shortened (P < 0·01) the interoestrous interval by 3·2 days. When assessed on Day 7 of pregnancy, administration of progesterone to superovulated donor cows on Days 1–4 of pregnancy did not affect early embryo development compared with superovulated cows treated with vehicle alone. Plasma progesterone increased rapidly in superovulated cows compared with cows during the oestrous cycle. The results indicate that administration of progesterone early in the oestrous cycle of the recipient can effectively advance uterine receptivity for the transfer of older asynchronous embryos.

Keywords: bovine; embryo; uterus; progesterone

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F. M. Clarke, C. Orozco, A. V. Perkins, I. Cock, K. F. Tonissen, A. J. Robins and J. R. E. Wells

Summary. An isolated preparation from ovine placental extracts which was active in the rosette inhibition assay mimicking the activity of the so-called 'early pregnancy factor' (EPF) has been shown to contain a 12 kDa polypeptide which could be partially resolved from low-molecular-weight active moieties. N-terminal amino acid sequence analysis of the polypeptide indicated that it was ovine thioredoxin, an identification confirmed by isolation and complete sequence analysis of the corresponding cDNA. The cDNA for human thioredoxin was expressed in Escherichia coli and the recombinant protein isolated and purified. Pure recombinant thioredoxin alone did not induce the expression of increased rosette inhibition titres (RITs) when tested in the rosette inhibition assay; but, when tested in combination with cell stimuli such as platelet-activating factor (PAF) or serum, it allowed the expression of increased RITs where none was achieved in its absence. Thioredoxin acted in the assay to reverse a refractory state normally induced by these stimuli, allowing lipoxygenase-dependent moieties also induced by the stimuli to exert their effects, resulting in the expression of increased RITs. Antibodies to recombinant thioredoxin removed from pregnancy sera the capacity to induce increased RITs, i.e. to express EPF activity, thus establishing a role for thioredoxin or thioredoxin-like proteins and associated molecules in the mechanisms which allow pregnancy sera to induce increased RITs. Based on a consideration of these and other results, a new model for the study of the EPF phenomenon is presented and discussed.

Keywords: early pregnancy factor; thioredoxin; molecular definition; man; sheep; mouse

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B A Refaat, A O Bahathiq, S Sockanathan, R L Stewart, M Wells and W L Ledger

Fallopian tubes from ten premenopausal women were collected and examined for the presence of inhibin, activin and its type IIA and IIB receptors (ActRIIA and ActRIIB) in the endosalpinx. Immunocytochemistry demonstrated clear staining for the βA, βB subunits and ActRIIA and ActRIIB that increased in intensity from the isthmus to the ampulla. No staining for the α subunit was observed. Whilst the staining of the βA subunit and ActRIIA was seen in almost every epithelial cell, staining for the βB subunit and ActRIIB was more variable. In situ hybridization and RT-PCR confirmed the presence of mRNA for the βA, βB subunits and ActRIIA and ActRIIB. These results indicated that the epithelium of the uterine tube is able to synthesize activin but not inhibin and has receptors for activin. Activins may thus act as paracrine regulators of tubal epithelial cell function, and embryonic activity may also bind to epithelial receptor and initiate intracellular processes that alter epithelial cell secretions.