Maintenance of the corpus luteum after uterine transfer of trophoblastic vesicles to cyclic cows and ewes

One or two trophoblastic vesicles (0.4-2 mm diam.) from cow (Day 14) or ewe (Day 11-13) embryos without their disc were transferred, after culture for 24 h, into recipients. Each vesicle was transferred into the uterine horn ipsilateral to the CL by the cervical route in heifers and surgically in ewes on Day 12 of the oestrous cycle. In cows, daily measurements of plasma progesterone concentrations and checks for return to oestrus showed that the CL was maintained in 8 out of 12 recipients. These 8 cows had 25- to 37-day cycles while 4 recipient heifers returned to oestrus normally. Three recipients with an extended cycle were slaughtered. The dissected uterus showed that trophoblastic vesicles had developed in the uterine horns. In ewes, the serum progesterone curve, determined in each recipient, showed that the CL was maintained in 7 out of 12 recipients. These 7 ewes had 20- to 54-day cycles and the other 5 ewes had a normal cycle of 15-19 days comparable to that of 17.0 +/- 0.5 days for the 6 control ewes. Whenever the CL was maintained, high blood progesterone levels were followed by rapid luteolysis. In cattle and sheep, therefore, a trophoblastic vesicle transferred into the uterus can develop in vivo, secreting the embryonic signals when there is no embryonic disc control and transforming the cyclic CL into a CL of pregnancy in about 60% of the cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intrauterine infusion of oestradiol-17 beta and prostaglandin E-2 on luteal function in non-pregnant heifers

Non-pregnant heifers (4/group) received intrauterine infusions of vehicle, oestradiol-17 beta (150 ng), PGE-2 (250 micrograms), or oestradiol + PGE-2 every 6 h from 12:00 h on Day 13 to 06:00 h on the day of subsequent oestrus or 06:00 h on Day 21 (day of oestrus = Day 0). Ten of 12 heifers receiving vehicle, oestradiol or PGE-2 returned to oestrus by Day 21, whereas none of the heifers receiving oestradiol + PGE-2 returned to oestrus by Day 21. Jugular venous progesterone concentrations of vehicle- and PGE-2-treated heifers declined rapidly after Day 15 and were basal (less than 1 ng/ml) by Day 20. For heifers receiving oestradiol infusions, systemic progesterone levels did not decline until after Day 18, but were again basal by Day 20. Heifers treated with oestradiol + PGE-2 maintained elevated systemic progesterone levels until Day 21 after oestrus. In addition, the corpora lutea of the heifers treated with oestradiol + PGE-2 were heavier (P less than 0.01) and contained more (P less than 0.05) progesterone than did corpora lutea of the heifers in the other 3 groups on Day 21 (3.4 g and 19.52 micrograms/g and 1.2 g and 1.65 micrograms/g, respectively). It is concluded that oestradiol-17 beta and PGE-2, both of which are produced by the bovine conceptus and secreted from the gravid uterus, may act synergistically to maintain luteal function during early pregnancy in the cow.

Changes in plasma estrogen, luteinizing hormone, follicle-stimulating hormone and 13,14-dihydro-15-keto-prostaglandin F2 alpha during blockade of luteolysis in pigs after human chorionic gonadotropin treatment

An injection of human chorionic gonadotropin (HCG) or estrogen on d 12 of the estrous cycle delays luteolysis in the pig. In an experiment to determine if HCG stimulated estrogen secretion, 21 cyclic pigs received one of five different amounts of HCG-(A) 0, (B) 125, (C) 250, (D) 500 or (E) 1,000 IU-as a single, im injection in 2 ml of distilled water on d 12 of the estrous cycle. Blood was collected from the jugular vein immediately before HCG injection and once daily thereafter until d 20 of the estrous cycle. Plasma progesterone, estrogen (unconjugated) and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were quantified for pigs in all groups; luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were quantified for pigs in groups A and E. The HCG injection exerted a dose-related increase on the mean interestrus interval (groups A, B, C, D and E were 20.5, 20.2, 22.5, 31.0 and 61.4 d, respectively) and on the delay of luteolysis as measured by mean plasma progesterone on d 16 (A, B and C vs D and E, respectively, 1.9, 1.2 and 10.4 vs 34.1 and 47.1 ng/ml; P less than .05). The HCG injection caused a transitory increase in plasma estrogen from d 12 (5 to 10 pg/ml before treatment) to d 15 (35.5 pg/ml, group D) and to d 16 (90.2 pg/ml, group E) before it decreased to preinjection levels on d 17 (group D) and 18 (group E).(ABSTRACT TRUNCATED AT 250 WORDS)

Current concepts of the endocrine characteristics of normal menstrual function: the key to diagnosis and management of menstrual disorders

Obviously, the endocrine mechanisms involved in producing the normal, cyclic pattern of menstrual bleeding are exceedingly complex. A review of even our current, far from complete, knowledge of the regulation of follicular growth, cyclic selection of a single dominant follicle, ovulation, and the neuroendocrine control of all three mechanisms only serves to emphasize the myriad of endogenous and exogenous factors that may adversely affect such a delicate balance and be manifest in menstrual disturbance. Indeed, one may wonder that the menstrual cycle is cyclic and predictable at all. Nevertheless, the efficiency with which the system normally operates is striking. Its very complexity often makes disorders of menstrual function a not infrequent symptom of disease outside the reproductive tract, a fact that should stress the need for prompt and thorough evaluation.

The clinical management of repeated early pregnancy wastage

A rational systematic evaluation is essential to the management of a couple with repeated early pregnancy wastage. Psychologic support in the form of frequent discussions and sympathetic counseling are crucial to the successful evaluation and treatment of the anxious couple. A prompt and orderly evaluation will relieve anxiety. When no etiologic factor is identified, a 60% to 80% fetal salvage rate may be expected. Once a patient conceives, serial ultrasonography, beta-hCG determination, and estradiol determination may be useful in detecting the stage of the embryonic death if subsequent abortion occurs. A karyotypic analysis of the products of conception should be performed if fetal loss occurs.

Control of luteal function during pregnancy: antiluteolytic and luteotropic properties of the developing mouse conceptus

Eight experiments were conducted to examine the influence of the conceptus on luteal function in mice. In uterine intact pseudopregnant mice, exogenous treatment with placental extracts or pregnant mouse plasma from Day 8 or Day 10 of gestation did not prolong the life span of the corpora lutea (CL). The interestrous interval (IEI) of hysterectomized pseudopregnant mice was extended by treatment with Day 10 placental extract and was accompanied by elevated plasma progesterone, consistent with the luteotropic nature of the Day 10 conceptus. The IEI of uterine intact pseudopregnant mice was prolonged by the presence of ectopically developing blastocysts and was further extended by a treatment with Day 10 placental extracts but not by treatment with Day 8 placental extracts. Although the ectopic blastocyst delayed the effect of the uterine luteolytic mechanism, there was no indication of luteotropic activity: the ectopic blastocysts were unable to activate the CL of the estrous cycle. In addition, plasma progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured in pseudopregnant, hysterectomized pseudopregnant and pregnant mice on Day 2 through 13 post-mating. The results of these experiments suggest a two-step mechanism in prolonging luteal function during pregnancy which involves two different substances. This mechanism involves an initial signal from the conceptus which blocks the uterine luteolytic mechanism and a subsequent luteotropic stimulus from the Day 10 conceptus which extends luteal life span to approximately the length of gestation.

The pattern of luteal phase plasma progesterone and estradiol in fertile cycles

Serum levels of progesterone and estradiol at early, middle, and late luteal phases were compared in nonfertile cycles in which only ovulation occurred to those in cycles in which ovulation was verified by conception. Two groups of patients were studied: 33 normal ovulatory women (12 of whom conceived) and 28 women who underwent induction of ovulation (8 of whom conceived). In each group, mean midluteal levels of progesterone and estradiol were essentially similar in nonfertile and fertile cycles. In fertile cycles, the late luteal levels of both steroids were higher than their respective midluteal values, whereas the late luteal values dropped in the nonfertile cycles. The late luteal rise in estradiol was found to be a more sensitive indicator of pregnancy than that of progesterone. The progesterone/estradiol ratio was stable during the luteal phase of fertile and nonfertile cycles. The ratio in spontaneous cycles was 34.4 +/- 4.7 and only 17.9 +/- 4.3 in induced cycles. This marked decrease suggests an impairment of steroid metabolism in women who require induction of ovulation.

Bilateral luteal maintenance in unilaterally pregnant pigs with infusions of embryonic extracts

Thirty unilaterally pregnant gilts with bilateral corpora lutea received infusions three times daily into a surgically isolated, nonpregnant uterine horn from d 12 through d 19 after mating. The infusions consisted of either saline alone or embryonic extracts in saline which were either untreated, heat-treated or charcoal-absorbed. The extracts were from porcine embryos, embryonic membranes and fluids between d 16 and 25 of pregnancy. While only 20% of the gilts infused with saline alone and none of those infused with charcoal-absorbed embryonic extracts maintained pregnancy to d 19, 100 and 83% of the gilts infused with untreated and heal-treated embryonic extracts, respectively, were pregnant on d 19. Similar treatment effects were observed for the incidence of bilateral luteal maintenance. No gilts receiving infusions of either saline or charcoal-absorbed embryonic extracts exhibited bilateral luteal maintenance. However, 67% of the gilts infused with untreated embryonic extracts and 67% of those infused with heated extracts had bilateral luteal maintenance on d 19. Additionally, the weights and progesterone concentrations of corpora lutea adjacent to the infused uterine horns were not different (P less than .05) from those of the corpora lutea adjacent the to pregnant uterine horns in gilts with bilateral luteal maintenance.

Corpus luteum maintenance during early pregnancy in the cow

Holstein heifers (18 pregnant, 12 inseminated but non-pregnant, and 17 cyclic) were studied during the first 18 days after oestrus. Jugular vein plasma progesterone concentrations were significantly (P < 0.05) higher in pregnant than in non-pregnant and cyclic animals between Days 10 and 18. Jugular oestradiol concentrations were also higher in pregnant than in cyclic animals between Days 6 and 16 (P < 0.05). No differences were found among the three groups in jugular LH levels during Days 1-18. Ovarian and uterine vein progesterone and oestradiol concentrations suggested that the elevated peripheral plasma concentrations of these steroids in pregnant animals were due mainly to increased ovarian production, but the embryo itself may have contributed to the oestradiol levels found at Day 17. Luteal tissues from pregnant animals contained more progesterone when incubated alone or with LH than tissues from cyclic animals (P < 0.06). However, LH-stimulated synthesis (incubated with LH minus incubated alone) was nearly identical for the three groups of tissues. Therefore, loss of responsiveness to LH does not appear to be the initial event in luteolysis. Concentrations of PGF in ovarian arterial plasma in cyclic and pregnant animals were similar at Day 18, although uterine vein concentrations were higher (P < 0.05) in the cyclic animals. Free arachidonic acid concentrations in corpora lutea at Day 18 were higher (P < 0.05) in cyclic than in pregnant animals. The data suggest that the embryo may produce one or more luteotrophic substances that stimulate increased progesterone secretion by the corpus luteum beginning as early as Day 10 of pregnancy.

Effect of oestrogen antisera early in gestation on pregnancy maintenance in the pig

Injection of antisera to oestradiol-17 beta and to oestrone from Days 10 to 21 of pregnancy had no effect on the maintenance of the corpora lutea or the initiation of placental attachment in the pig.

Effect of the fetal placenta and of a rabbit pituitary extract on plasma progesterone in fetectomized rabbits

When fetuses and placentas were removed on Day 18 in normal pregnant rabbits, plasma progesterone levels declined rapidly to non-pregnant values within 48 h. This decline was largely prevented if only fetectomy was performed, leaving the placentas in situ, but not when the fetal components of the placentas were also removed. These results suggested that ovarian progesterone production was dependent upon trophic influences emanating from the fetal portions of the placentas. Ovarian progesterone production was maintained by an extract of rabbit pituitaries for at least 72 h after removal of fetuses and placentas.

[Role of hormonal receptors in the regulation of the corpus luteum (author's transl)]

Recent publications dealing with the hormonal regulation of the corpus luteum function have been reviewed. Hormones involved in this regulation are: LH and placental analogue hCG, FSH, prolactin and placental analogue hPL, prostaglandins, oestradiol and androgens. The hormone receptor interaction in the luteal cells and the role of each hormone in the modulation of the cell responsiveness has been reviewed.