Our knowledge about the oviducal functions is still incomplete. The Fallopian tube is not merely a conduit for the passage of spermatozoa and ova, but it provides a favourable environment, by virtue of its luminal fluid, for the gametes and for the fertilized and cleaving ovum (Hamner & Fox, 1968, 1969; Stegner, 1969; Hamner, 1971). Furthermore, the uterine environment doubtless provides shelter and nourishment for the developing and implanting conceptus. During the whole period of gestation the embryo depends upon the milieu provided by the maternal organism, and even during pre-implantation there exists a well documented dependency of the blastocyst upon the maternal substrates, provided by the oviducal and uterine tissues. From the very beginning of development, from the establishment of an individual genome, there exist two closely related systems: the embryonic and the maternal system. But, taking into consideration morphological and biochemical analyses, one must recognize that both these
H. M. BEIER
M. Beato and H. M. Beier
Summary. A uteroglobin-like protein was prepared from lung extracts of female rabbits by absorption to immobilized anti-uteroglobin immunoglobulin and purified to homogeneity by gel filtration on Sephacryl S-200. The final preparation is indistinguishable from uteroglobin according to its behaviour in Ouchterlony double-diffusion, polyacrylamide gel electrophoresis under denaturing and non-denaturing conditions, ultraviolet spectrum, tryptic peptide analysis, and progesterone-binding properties. Progesterone binding to the lung protein exhibits an affinity similar to that observed with authentic uteroglobin and is equally enhanced by reduction of the protein with dithiothreitol. Competition experiments with non-radioactive steroids demonstrate a similar steroid-specificity for both proteins. Progesterone binding causes a perturbation in the ultraviolet absorbance of tyrosine residues of the lung protein similar to that observed with uteroglobin. These data suggest that the proteins prepared from both sources are biochemically identical.
R. R. Maurer and H. M. Beier
Summary. The effects of isolated protein fractions from rabbit uteri (prealbumin, albumin, uteroglobin, and β-glycoprotein), unfractionated uterine proteins, progesterone, oestradiol-17β, and prostaglandin F-2α on the development of rabbit embryos in vitro were investigated. When exposed to individual protein fractions obtained from Day-6 uteri, 8-cell embryos did not develop into early blastocysts; morulae readily developed into early blastocysts, but further development was retarded. Progesterone (10−5–10−11 M) and prostaglandin F-2α (0·1–10 ng/ml) added to the medium slowed development of blastocysts to advanced stages. Growth of 8- to 16-cell embryos, morulae, and Day-4 blastocysts was stimulated by unfractionated uterine proteins obtained from Day-5 uterine flushings.
Although embryos cultured in medium containing BSA had similar rates of blastocyst formation and, ultimately, similar blastocyst expansion as did the embryos cultured in medium with unfractionated proteins, the radial and immediate expansion of the early blastocysts cultured in the latter approximated that found in utero.
H. M. Beier, W. Elger, C. Hegele-Hartung, U. Mootz and K. Beier-Hellwig
Summary. We describe a well-established approach for studying the parameters and mechanisms of synchronization or desynchronization between the maternal and embryonic systems before implantation. It is useful for inducing 'delayed secretion' of the endometrium by different endocrine interventions, which dissociate the endometrial transformation from its control by the corpus luteum. The technique has been achieved by means of direct progesterone antagonists which competitively bind to the progesterone receptor and, in turn, inhibit the physiological effects of progesterone. During the luteal phase, secretory protein patterns indicate the receptive stage of the endometrium. Evidence is presented to show that these patterns, analysed by electro-phoresis and densitometry, define the time at which an embryo transfer is promising for implantation and establishment of pregnancy.
Keywords: uterine proteins; corpus luteum, blastocyst; implantation; progesterone antagonists; human
W. Schlegel, B. Fischer, H. M. Beier and H. P. G. Schneider
Summary. PGE-2 and PGF-2α in rabbit semen were selectively inactivated by incubation with antisera, or most of the seminal prostaglandins were transformed into biologically inactive 15-keto-prostaglandins by prostaglandin-15-hydroxydehydrogenase (PG-15-HDH). These treated ejaculates were vaginally inseminated. Compared to the controls (738 eggs of which 94% were fertilized) a dose-dependent reduction of the fertilization rate was observed with the anti-PGF-2α-treated ejaculates. A nonuniformly, but statistically significantly reduced fertility was found in the other 2 treatment groups. After incubation with higher doses of PG-15-HDH, some fertilization was accomplished with ejaculates showing an extremely weak forward progression or immotile spermatozoa. An improvement in sperm motility, however, was observed in ejaculates treated with antiserum to PGF-2α. Seminal prostaglandins may not exclusively affect sperm motility. The observed influences on the fertilization rate after treatment of spermatozoa with antisera to PGE-2 and PGF-2α or PG-15-HDH suggest that these are local effects in the female genital tract.
W. Schlegel, S. Krüger, D. Daniels, B. Fischer, H. P. G. Schneider and H. M. Beier
Summary. Corpora lutea and ovarian stromal tissue were anlaysed for prostaglandin (PG) concentrations and activities of enzymes involved in PG metabolism at 8, 10, 12, 13 and 15 days after induction of ovulation. In CL of pseudopregnant rabbits, the PGE-2–9-ketoreductase (PGE-2–9-KR) was highly active on Days 10, 12 and 15 when compared with Day 8 (P < 0·01; P < 0·001; P < 0·05). In pregnant animals PGE-2–9KR activity was only increased on Day 12 (P < 0·05) but declined to basal levels on Days 13 and 15. Comparing PGE-2–9-KR activity of pseudopregnant and pregnant animals, a significant elevation was found on Day 15 of pseudopregnancy (P < 0·025). Activities of PG-15-hydroxydehydrogenase did not exhibit any significant changes with time in pseudopregnant or pregnant rabbits.
PGE-2 concentrations were increased on Days 12, 13 and 15 (P < 0·025) when compared with Day 8. Changes in PGF-2α concentrations paralleled those of PGE-2–9-KR. The concentrations of PG metabolites 13,14-dihydro-15-keto-PGE-2 and -PGF-2α were lower than those of the primary PGs and did not show stage-specific changes in pseudopregnant and pregnant animals.
These results demonstrate that the rabbit CL posesses enzymes to convert PGE-2 to PGF-2α and to metabolize both PGs. PGE-2–9-KR may be involved in regulating the PGF-2α/PGE-2 ratio and possibly in controlling the life-span of the corpus luteum.
Keywords: PGE-2-9-ketoreductase; prostaglandin-15-hydroxydehydrogenase; luteolysis; prostaglandin metabolism; pseudopregnancy; rabbit