Large Amounts Of Progesterone Research Articles

Ovarian response and conception rate in Boran and Boran*Holstein cows treated by Gonadotrophin-realizing hormone and ProstaglandinF2α with and without exogenous progesterone

BackgroundDifference in breed, nutrition status and climate in which animals are managed result in differences in response to reproductive hormones. Fertility rate to artificial insemination is very low in Ethiopian Boran and Boran*Holstein crosses. This partly maybe due to adopting estrus and/or ovulation synchronization developed for temperate taurine cattle. Experimental study was conducted to evaluate ovarian response to combinations of Gonadotrophin-Realizing Hormone agonist (gonadorelin) and ProstaglandinF2α (PGF2α) with or without progesterone (Controlled Internal Drug Release/CIDR), and conception rate to timed AI. Postpartum native Ethiopian Boran (n = 60) and Boran*Holstein cross (n = 66) cows were randomly assigned to four treatment groups as Ovsynch (gonadorelin on day of start, PGF2α seven days later, 2nd gonadorelin at 48 h of PGF2α and insemination at 19 h of the 2nd gonadorelin); CIDR + Ovsynch (same as Ovsynch but CIDR device was inserted into vagina for 7 days); Cosynch (same as Ovsynch but insemination was made at the 2nd gonadorelin) and CIDR + Cosynch (same as Cosynch but CIDR was inserted for 7 days).ResultThere was no difference (P > 0.05) in ovulation rate to day 9 gonadorelin (88.33% in Boran; 78.79% in Boran*Holstein) and interval from day 9 gonadorelin to ovulation (36.5 ± 1.13 h in Boran and 36.057 ± 1.11 h in Boran*Holstein). Dominant follicle immediate to ovulation (14.95 ± 0.19 mm Vs 19.12 ± 0.49 mm) and corpus luteum size (16.31 ± 0.33 mm Vs 20.28 ± 0.43 mm ) respectively were smaller (P < 0.05) in Boran than Boran*Holstein. Plasma progesterone concentration at PGF2α was higher (P < 0.05) in Boran (11.91 ± 0.74ng/mL) than Boran*Holstein (6.13 ± 0.27ng/mL) but luteolysis rate was lower (P < 0.05) in Boran (87.9%) than Boran-Holstein (96.9%). Cows with CIDR had higher conception rate than cows without CIDR (72.00% Vs 39.02% in Boran*Holstein and 74.07%, Vs 51.52% in Boran respectively). Insemination at 19 h of gonadorelin administration resulted in higher conception rate (78.6% for Boran; 71.43% for Boran*Holstein) than insemination at gonadorelin (69.29% for Boran; 66.67% for Boran*Holstein).ConclusionBoran cows have smaller preovulatory follicles, smaller corpus luteum, large amount of progesterone and lower rate of luteolysis to PGF2α compared to Boran*Holstein. The CL of Boran cattle seems les reactive to PGF2α than Boran*Holstein CL. CIDR significantly improved conception rate in Boran and Boran*Holstein cows.

Comparison of Placental HSD17B1 Expression and Its Regulation in Various Mammalian Species.

During mammalian gestation, large amounts of progesterone are produced by the placenta and circulate for the maintenance of pregnancy. In contrast, primary plasma estrogens are different between species. To account for this difference, we compared the expression of ovarian and placental steroidogenic genes in various mammalian species (mouse, guinea pig, porcine, ovine, bovine, and human). Consistent with the ability to synthesize progesterone, CYP11A1/Cyp11a1, and bi-functional HSD3B/Hsd3b genes were expressed in all species. CYP17A1/Cyp17a1 was expressed in the placenta of all species, excluding humans. CYP19A/Cyp19a1 was expressed in all placental estrogen-producing species, whereas estradiol-producing HSD17B1 was only strongly expressed in the human placenta. The promoter region of HSD17B1 in various species possesses a well-conserved SP1 site that was activated in human placental cell line JEG-3 cells. However, DNA methylation analyses in the ovine placenta showed that the SP1-site in the promoter region of HSD17B1 was completely methylated. These results indicate that epigenetic regulation of HSD17B1 expression is important for species-specific placental sex steroid production. Because human HSD17B1 showed strong activity for the conversion of androstenedione into testosterone, similar to HSD17B1/Hsd17b1 in other species, we also discuss the biological significance of human placental HSD17B1 based on the symptoms of aromatase-deficient patients.

Human ovarian follicular development: From activation of resting follicles to preovulatory maturation

By integrating morphometrical and endocrinological data, as well as biological effects of various molecules synthesized by the human follicle, we propose a dynamic view of the follicle growth within the human ovary. Folliculogenesis starts with entry of resting follicles into the growth phase, a process where the kit system plays a key role. Several months are required for a new growing follicle to reach the preantral stage (0.15 mm), then 70 additional days to reach the size of 2 mm. Early growing follicle growth is regulated by subtle interactions between follicle-stimulating hormone (FSH) and local factors produced by theca and granulosa cells (GCs), as well as the oocyte. From the time they enter the selectable stage during the late luteal phase, follicles become sensitive to cyclic changes of FSH in terms of granulosa cell proliferation. During the early follicular phase, the early selected follicle grows very quickly and estradiol is present in the follicular fluid. However, the total steroid production remains moderate. From the mid-follicular phase, the preovulatory follicle synthesizes high quantities of estradiol, then after the mid-cycle gonadotropin surge, very large amounts of progesterone. At this stage of development, the responsiveness of the follicle to gonadotropins is maximum, especially to luteinizing hormone (LH) that triggers granulosa wall dissociation and cumulus expansion as well as oocyte nuclear maturation. Thus, as the follicle develops, its responsiveness to gonadotropins progressively increases under the control of local factors acting in an autocrine/paracrine fashion.

350 EFFECT OF PROGESTERONE SUPPLEMENTATION OF MATURATION MEDIUM ON DEVELOPMENT OF IVM-IVF-IVC BOVINE EMBRYOS

Follicular fluid from small and large bovine follicles contains large amounts of progesterone, and during preovulatory period progesterone concen- tration increase markedly by 18 h after LH surge. Furthermore, cumulus cells express membrane progestin receptor beta (Liu et al. 2008 Steroids 73, 1416-1423). For these reasons, we hypothesized that progesterone supports maturation of preovulatory bovine oocytes to MII stage. The object of this study was to investigate the effect of progesterone supplementation of in vitro maturation medium on competence of bovine oocyte to develop into blas- tocysts in vitro. COCs were collected by the aspiration of 2-6 mm follicles from ovaries within 6 h of slaughter. The COCs were divided into 5 groups: (1) a control group, TCM-199 supplemented with 5% calf serum (CS) as IVM medium, and (2 to 5) progesterone (P4) supplementation groups, TCM- 199 supplemented with 5% CS and 1, 3, 5, and 10 μg mL-1 of P4. Groups of 10 COCs were incubated in 50-μL drops of IVM media at 38.5°C under an atmosphere of 5% CO2 in air for 20 h. The matured COCs were inseminated with 3 × 106 sperm mL-1. After 18 h of gamete co-culture, the pre- sumptive zygotes were cultured in CR1aa media supplemented with 5% CS for 9 days at 38.5°C under an atmosphere of 5% CO2, 5%O2, and 90% N2. Embryonic development was evaluated at 48 h after IVF (total cleavage rates) and on Days 7 to 9 (blastocyst rate). Data was analyzedby chi-square test. The results are presented in Table 1. There were no significant differences in the cleavage rates between treatments. However, the blastocyst formation rate of 5 μg mL-1 P4 supplementation group was significantly higher than that of 10 μg mL-1 P4 supplementation group (P &lt; 0.05). In addition, the blastocyst formation rates of 10 μg mL-1 P4 supplementation group was lower than the other groups. These results suggest that progesterone supple- mentation of in vitro, maturation medium affects the competence of the oocytes to develop into blastocysts in vitro, and 5 μg mL-1 P4 supplementation may be effective in increasing embryo production. Furthermore, 10 μg mL-1 P4 supplementation has negative effect on the oocyte competence. Table 1.Effect of progesterone supplementation on development of IVF bovine embryos

Progesterone and an aftermath to FIGO2009

Progesterone and an aftermath to FIGO2009

Steroid hormones concentration in the postovulatory follicles of the goose

The purpose of the present investigation was to measure the concentrations of progesterone (P4), androgens (A) and estradiol (E2) in follicular wall of the three largest postovulatory follicles. The major findings in the present study are: 1) the postovulatory follicles of the goose, which are not homologous with the mammalian corpus luteum, are an active endocrine tissue. 2) Follicular wall of postovulatory follicles can synthesize large amounts of progesterone and lesser amounts of androgens and estradiol. This study also suggest that the steroidogenic potential of the follicular cells was markedly reduced during the process of follicular regression.

Effect of Feed Allowance During Rearing and Breeding on Female Broiler Breeders.: 3. Ovarian Steroidogenesis

The influence of feed allowance during rearing (4 to 18 wk) and breeding (18 to 62 wk) on in vitro follicular steroidogenesis was examined. Four feeding programs were imposed: FF, consumed feed ad libitum throughout; FR, provided ad libitum access from 0 to 18 wk of age and restricted thereafter; RF, provided ad libitum access to feed from 0 to 4 wk, restricted from 4 to 18 wk, and consumed feed ad libitum thereafter; RR, consumed feed ad libitum from 0 to 4 wk of age and restricted thereafter. All birds received a starter diet (2,739 kcal ME/kg, 19.1% CP) from 0 to 3 wk of age, a grower diet (2,729 kcal ME/kg, 15.5% CP) from 3 to 22 wk of age, and a layer diet (2,889 kcal ME/kg, 14.6% CP) from 22 to 62 wk of age. Restricted feeding was based on commercial guidelines. At 33 wk of age, 10 to 12 (FF = 10, FR = 12, RF = 10, and RR = 11) birds from each feeding regimen were killed by cervical dislocation and the follicles removed for in vitro steroidogenesis.Feed allowance during breeding (18 to 62 wk) had a significant effect on in vitro follicular steroidogenesis at 33 wk of age. In broiler breeders fed ad libitum, some of the F2 (second largest) follicles had an endocrine profile characteristic of the F1 (largest) preovulatory follicles, secreting very little androstenedione and large amounts of progesterone. In feed-restricted birds, only the F1 follicles, which were destined to ovulate next, secreted any significant amount of progesterone into the culture media. Compared with restricted feeding, ad libitum feeding significantly increased the production of androstenedione in small white follicles (<1 mm). The steroidogenic capability of the F2 follicle to secrete a significant amount of progesterone appeared to be part of the physiological mechanisms leading to multiple ovulations. It is not clear how an increased intake of nutrients in birds fed ad libitum causes these endocrine alterations.

Studies on Regulatory Mechanisms for Gonadotropins Secretion in Lactating Rats

The present study was designed to clarify mechanisms responsible for regulation of FSH and LH secretion and ovarian follicular maturation during lactation in rats. Throughout lactation in rats, plasma levels of follicle-stimulating hormone (FSH) remain within the range normally found during the diestrous phase of the estrous cycle, regardless of litter size, although levels of luteinizing hormone (LH) in plasma are consistently lower in dams nursing 8 pups than in dams nursing 2 pups. All antral follicles larger than 401μm in diameter degenerate during the first half of lactation and do not reappear until the second half of lactation in rats nursing 8 pups. Healthy follicles of this size, however, are always present in mothers nursing 2 pups. These changes in follicular degeneration corresponded with a decrease in concentrations of plasma LH in the first half of lactation, and follicular development was noted with an increase in basal levels of plasma LH in the second half of lactation. Corpora lutea formed after postpartum ovulation secrete a large amount of progesterone under the influence of prolactin released as a result of suckling. Despite continued suckling, plasma concentrations of prolactin and progesterone decline gradually and a slight increase in plasma concentrations of estradiol-17β occurs during the second half of lactation. Concentrations of bioactive and immunoreactive inhibin in plasma vary with the number of healthy antral follicles and no positive correlation has been observed with luteal function throughout lactation in the rat.On the basis of the present results it is indicated that 1) tonic secretion of LH is an important factor in normal follicular maturation and maintenance in lactating rats, 2) the suckling stimulus, rather than ovarian factors, is mainly responsible for the suppression of FSH as well as LH secretion during the first half of lactation in rats nursing 8 pups. On the other hand, during the second half of lactation in rats nursing 8 pups, ovarian inhibin plays a primary role in the suppression of FSH secretion, whereas ovarian steroids act to suppress LH secretion. The present findings also indicate that 3) the suckling stimulus alone suppressed the secretion of both LH and FSH and this effect may be mediated by the inhibition of LH releasing hormone (LH-RH) secretion from the hypothalamus, 4) the suckling-induced inhibition of LH-RH may be primarily mediated by endogenous corticotropin-releasing hormone and opioid peptides and 5) the pituitary-adrenal system is capable of influencing the maintenance of a normal secretion of gonadotropins and prolactin as well as the maintenance of ovarian function during the lactation in the rat.

Regulation of Heat Shock Protein Synthesis by Gonadotropins in Cultured Granulosa Cells*

Primary cultures of granulosa cells can be stimulated to produce large amounts of progesterone by gonadotropins. This stimulation is associated with significant changes in the expression of several major proteins, as revealed by two-dimensional gel electrophoresis. These changes include a decrease in the synthesis of actin cytoskeleton proteins and an increase in the synthesis of a few abundant proteins, one of which is a mammalian heat shock protein, hsp90. Under culture conditions that have previously been shown to bring about the maturation of granulosa cells into progesterone-producing cells (i.e. treatment with gonadotropins or cAMP or by disrupting the actin cytoskeleton with cytochalasin), an increased synthesis of hsp90 could be demonstrated. Freshly isolated granulosa cells isolated from PMSG-treated animals synthesize hsp90 at a much higher level than cells isolated from diethylstilbestrol-treated rats. Kinetic studies have shown that granulosa cells isolated from diethylstilbestrol- or PMSG-treated rats synthesize high levels of hsp90 if maintained in culture in the presence of gonadotropins, but rapidly decrease hsp90 synthesis in the absence of gonadotropins and increase the synthesis of actin cytoskeleton proteins. Furthermore, in cells cultured for 48 h in the presence of cytochalasin-B followed by incubation for 24 h in the absence of the drug, the synthesis of hsp90 and several other proteins characteristic of mature granulosa cells decreased, while that of the actin cytoskeleton increased. In vitro translation assays and Northern blot analyses suggest that hsp90 synthesis in gonadotropin-stimulated cells may be regulated by mRNA translational efficiency. Taken together with recent findings in which hsp90 was identified in complex with cytoplasmic steroid receptors and the hormonal regulation of hsp90 content in target tissues, the results support the notion that hsp90 plays a role in the control of steroid hormone action.

Interovarian relationship in the secretion of progesterone during the luteal phase of the capuchin monkey (Cebus apella).

In basal conditions, progesterone concentrations were similar in the ovarian veins of the ovary +CL (3211 +/- 526 ng/ml) and the ovary -CL (3165 +/- 554 ng/ml), but after blocking the blood flow between the ovary +CL and the uterus, the progesterone values in the vein draining the ovary -CL decreased to 1218 +/- 394 ng/ml (P less than 0.01). When [3H]progesterone was injected in the ovary +CL, the radioactivity appeared earlier and more concentrated in the vein draining the ovary -CL (30 sec, 0.53% of injected dose) than in the femoral vein (150 sec, 0.08% of injected dose). Removal of the ovary +CL was followed by a brief maintenance of peripheral progesterone within luteal-phase levels. The in-vitro progesterone production by a suspension of cells isolated from the corpus luteum was 47.5 +/- 12.8 ng/ml/2 h, whereas luteal-like cells isolated from the ovary -CL secreted 14.3 +/- 6.0 ng/ml/2 h (P less than 0.01) into the medium. We therefore suggest that the symmetrical and high secretion rate of progesterone by the ovaries of the capuchin monkey indicates a between-ovary communication system, and that the luteal-like tissue of the ovary -CL can produce relatively large amounts of progesterone.

Changes in 3 beta-hydroxy- delta 5-steroid dehydrogenase activity in granulosa tissue during the ovulatory cycle of the laying hen (Gallus domesticus).

The object of this study was to examine changes in the activity of granulosa 3 beta-hydroxy-delta 5-steroid dehydrogenase during the ovulatory cycle of the domestic fowl. The enzyme activity in granulosa tissue from the largest follicle increased significantly during the period 8-14 h before an expected ovulation. The increase in activity occurs before the preovulatory surge of LH and near the time of lights off. During the 4-8 h period before an ovulation, i.e. the time of maximal plasma LH concentrations, 3 beta-hydroxy-delta 5-steroid dehydrogenase activity decreased in granulosa tissue from the largest follicle. This observation is explained by proposing that the enzyme is inhibited by the large amounts of progesterone found in the tissue at this time. The results indicate that important biochemical changes are taking place within granulosa tissue of the largest ovarian follicle before the preovulatory LH surge.

Bipotential Actions of Estrogen on Progesterone Biosynthesis by Ovarian Cells. I. Relation of Estradiol's Inhibitory Actions to Cholesterol and Progestin Metabolism in Cultured Swine Granulosa Cells*

In short term, serum-free cultures of granulosa cells, estradiol inhibited basal progesterone production by more than 84% in a time- and dose-dependent fashion. Half-maximal inhibition (ID50) was observed at a mean estradiol concentration of 70 ng/ml. The acute inhibitory effects of estradiol were independent of cell density or maturational status of the parent follicle (small, medium, or large follicles). Estrogen decreased total progesterone biosynthesis, rather than merely progesterone secretion by granulosa cells. In addition, the production of progesterone and its 20 alpha-reduced metabolite were suppressed in parallel over a 30-fold range of inhibitory effects. Moreover, estradiol inhibited progesterone production from both endogenous and exogenous (25-hydroxycholesterol) substrate. In contrast to its inhibition of progesterone production, estradiol acutely enhanced pregnenolone accumulation and led to a 14- to 20-fold increase in the ratio of pregnenolone to progesterone. Inhibition of 3 beta-hydroxysteroid dehydrogenase activity was confirmed by demonstrating estrogen's ability to antagonize the conversion of exogenously supplied pregnenolone to progesterone in intact granulosa cells (ID50, 74 ng/ml) and to directly inhibit enzymic activity in ovarian homogenates (ID50, 79 ng/ml). On the other hand, estradiol did not alter the incorporation of [14C]acetate into cholesterol and specific progestins or influence the time-dependent hydrolysis of prelabeled cholesteryl ester stores in granulosa cells. In summary, in short term cultures of swine granulosa cells, estradiol significantly inhibits basal progesterone biosynthesis in a time- and dose-dependent fashion, encompassing estradiol concentrations attainable in vivo. Estrogen's inhibition is accomplished by mechanisms that are independent of cytotoxicity, cell density, and maturational stage of the parent follicle. The predominant locus of estrogen action is blockade of pregnenolone's conversion to progesterone, rather than accelerated metabolism of progesterone to its 20 alpha-reduced metabolite. Moreover, estradiol simultaneously enhances functional cholesterol side-chain cleavage activity without suppressing de novo cholesterol biosynthesis or impairing the mobilization of cellular cholesteryl ester stores. Thus, we infer that increasing concentrations of estradiol attained in antral follicular fluid during the later stages of follicle maturation could effectively limit the premature secretion of large quantities of progesterone before ovulation without impairing the cell's capacity for de novo cholesterol biosynthesis or cholesteryl ester hydrolysis.

An ovarian role in prolonging and terminating the two surges of prolactin in pseudopregnant rats.

Daily nocturnal (N) and diurnal (D) surges of PRL are characteristic of a pseudopregnancy (psp) induced by cervical stimulation (CS). These semicircadian surges persist for 13-14 days, after which time they cease, and psp ends. The purpose of this study was to describe the involvement of the ovarian steroids in the maintenance and termination of the N and D surges of PRL. CS of long term ovariectomized (OVX) rats resulted in N and D surges of PRL lasting 14 days. By day 16 after CS, neither surge of PRL was present. The sc placement of Silastic implants containing large quantities of progesterone in long term OVX-CS rats sustained and enhanced the N surge of PRL until at least day 16. The D surge was also sustained until day 16, but its magnitude was normal. Estradiol alone was capable of maintaining the D but not the N surge for this same time interval. However, pharmacological quantities of estradiol restricted the magnitude of the N surge generated in the progesterone-implanted animal. Since neither surge of PRL was present by day 14 after CS in intact rats, but at least the nocturnal surge was still present at this time in long term or acutely OVX rats, this implies an active role of ovarian steroids in the termination of PRL surges at the end of psp. At the end of psp, luteal progesterone secretion declines and follicular estradiol secretion increases. Varying sizes of Silastic implants containing progesterone or estrogen were placed into psp animals after acute ovariectomy on day 9 to approximate this ovarian steroid secretory pattern of intact psp rats. Only when the decrease in progesterone was coupled with a modest increase in estrogen was there a total cessation of the two daily surges of PRL in OVX-CS rats. The data suggest that the PRL surges end in the intact psp rat due to the waning response to CS as well as the shifting steroid ratio represented by the fall in progesterone in the presence of a small amount of estrogen.

Regulation of steroidogenesis in the human placenta

Large quantities of progesterone and ocstrogens are synthesized during human pregnancy and the principal steps of biosynthesis occurring in the placenta are quite well-known. The progesterone synthesis is difficult to study because it derives from the important endogenous pool of free and esterified cholesterol, and the only enzymatic system studied is the 3β HSDH 4ene → 5ene isomerase. The placenta acquires during the course of pregnancy a gradually increasing power of aromatization. LH. HCG and some PG stimulate the oestrogen biosynthesis, this effect being probably mediated by cAMP. Otherwise some enzymes such as 5-ene-3β sulphatase and 5-ene-3β HSDH are directly inhibited by some endogenous steroids. Significant differences have been observed in the characteristics of both enzymatic activities according to the use of C 19 or C 21 substrates, with higher affinities ( K M ) tor the latter ones. Moreover some progestative agents, such as chlormadinone acetate, induce a decrease of the oestrogen biosynthesis by a 5-ene-3β sulphatase deficiency which could spontaneously occur in pregnancies with male fetus. This X-linked recessive character has no consequence on the fetal development, but is frequently associated with an ichthyosis.

Regulation of testosterone synthesis in the fetal mouse testis

Plasma testosterone (T) levels were determined by radioimmunoassay in male and female mouse fetuses from day 13 (1 day after sexual differentiation) to day 18 (1 day before parturition). T levels in plasma of male fetuses were significantly higher than those of female. In male fetuses, plasma T levels rose from day 13 to a peak level at 16–17 days. before declining on day 18. On the other hand, large amount of progesterone (P) was present in blood of pregnant mice over the observed period. This finding may indicate that progesterone of maternal origin is available as a potential precursor for T biosynthesis by the fetal testis. However, the dissociation between maternal P and fetal T levels between day 15 and day 16 of gestational age may suggest a more complex regulation of fetal T synthesis.

Accumulation of steroids in rabbit preimplantation blastocysts.

The concentrations of progesterone, androstenedione, testosterone, oestrone and oestradiol were measured by radioimmunoassay in blastocysts and uterine fluid flushings collected from rabbits 110 to 159 h post coitum (p.c.). None of the blastocysts or uterine flushings contained detectable levels of androstenedione, testosterone or oestrone. All uterine flushings contained large amounts of progesterone and some of the flushings also contained oestradiol. A small amount of progesterone (approximately 7-5 pg/blastocyst) was first detectable in some blastocysts at 135 h p.c.; progesterone levels/blastocyst then increased progressively, reaching levels of about 122-158 pg/blastocyst at 159 h p.c. Micropuncture of blastocysts at 159 h p.c. indicated that greater than or equal to 90% of the progesterone in the embryo was in the blastocoelic fluid. Blastocysts from rabbit uterine horns containing oestradiol also contained oestradiol but those in which oestradiol was detected were never observed in uteri lacking the hormone. It is inferred that rabbit blastocysts accumulate both progesterone and oestradiol from uterine fluid.

Steroid hormone production by sheep ovarian follicles cultured in vitro.

Summary. Large intact follicles and granulosa cells were obtained from sheep ovaries at various stages of the oestrous cycle and were cultured in vitro for 7 days. The daily output of steroid hormones into the culture medium was determined using a procedure capable of measuring a wide range of steroids including immunoreactive oestrogen, testosterone, androstenedione, progesterone, 20α-hydroxy-pregn-4-en-3-one, 17α-hydroxyprogesterone, 17α,20α-dihydroxy-pregn-4-en-3-one, pregnenolone, 17α-hydroxypregnenolone and certain hydrogenated metabolites. Intact follicles explanted from sheep on Day 4 of the cycle produced oestrogen (40 ng/mg follicular tissue per 24 hr) during the first 3 days in culture followed by large amounts of testosterone (100 ng/mg per 24 hr) and finally 17α-hydroxylated progestin. Follicles explanted at midcycle produced constant amounts of oestrogen (30 ng/mg per 24 hr) throughout the culture period; no other steroids were produced in significant quantities. The highest levels of oestrogen (75 ng/mg per 24 hr) were produced by follicles which had been explanted from sheep on Day 14 of the cycle. Oestrogen production declined rapidly in follicles explanted just before oestrus (late Day 15) and was replaced by the production of testosterone and 17α-hydroxylated progestin. The production of oestrogen and testosterone was very low in follicles explanted at oestrus; these follicles produced a transient peak of 17α-hydroxypregnenolone (30 ng/mg per 24 hr) followed by large amounts of progesterone (300 ng/mg per 24 hr) and 20α-hydroxy-pregn-4-en-3-one (250 ng/mg per 24 hr). Monolayer cultures of granulosa cells produced only progesterone, 20α-hydroxy-pregn-4-en-3-one and pregnenolone, thus implicating the cells of the theca interna as the principal source of oestrogen, androgen and 17α-hydroxylated progestin. Our findings indicate that the biosynthesis of oestrogen in the cells of the theca interna involve a sequence of steps including pregnenolone → 17α-hydroxypregnenolone→17α-hydroxyprogesterone→ testosterone or androstenedione→ oestrogen. During the transformation of follicles from oestrogen to progesterone secretors, steroid synthetic capacity is transferred from the theca interna to the membrana granulosa. The accumulation first of testosterone and then of 17α-hydroxypregnenolone suggests that the aromatase and then the desmolase systems limit steroid production in the theca interna during the period of transformation.

Concentrations of progesterone in the plasma of mothers and infants at time of birth.

Extract: A higly sensitive method utilizing competitive protein binding was used to study concentrations of progesterone in the plasma of mothers, in umbilical cord plasma, and in the plasma of full-term and premature infants in the immediate postpartum period. Blood samples were obtained from 20 mothers during labor and from the cords of their infants at delivery. Most of these infants were also studied at 2 or 3 days of age. For purposes of comparison, a second series of samples was obtained from control subjects using needle aspiration to obtain samples from the umbilicus; 14 samples were studied. In the mothers, concentrations of progesterone in plasma ranged from 46 to 387 ng/ml (mean: 129 ± 78 SD); in cord blood, progesterone levels ranges from 440 to 2,000 ng/ml (mean: 1,030 ± 412 SD); and in blood from the umbilical vein, concentrations of progesterone ranges from 310 to 720 ng/ml (mean: 562 ± 140 SD). A total of 27 full-term newborns was studied at 24, 48, and 72 h of life. In four cases, blood was obtained from the same infant at 12,24, and 72 h of life. The highest concentrations of progesterone were noted during the first 24 h of life, with levels ranging from 13 to 32 ng/ml (mean: 19 ng/ml) at 12 h, and from 2 to 32 ng/ml (mean: 16 ng/ml) at 24 h. By day 2, levels of progesterone had decreased to 3-20 ng/ml (mean: 10 ng/ml) and by day 3 were reduced to 0-16 ng/ml (mean: 8 ng/ml). Thirty-two premature infants, with birth weights of from 1,317 to 2,465 g, and ranging in gestational age from 30 to 40 weeks, were also studied. In several cases serial blood samples were obtained by the same methods used with the full-term infants. Two sets of twins were included. In premature infants, decreasing rapidly to 2-6 ng/ml (mean: 3 ng/ml) by 24 h of life. These low concentrations poersisted throughout days 2 and 3. There was no singnificant difference between concentrations of progesterone in plasma in full-term and premature infants at 2-3 days of age. It appeated that premature infants were as able to clear progesterone from the plasma as were the full-term infants. Speculation: The data obtained in this study support the concept that large amounts of progesterone are delivered from the placenta to the fetus. This compound may be a precursor of C-21 steroids such as cortisol, synthesized by the fetal adrenal. Preogesterone has also been shown to effect respiration in animals and man [7, 8, 14, 15] and an effect on neonatal respiratory mechanisms and diease may occur, although this has not been demonstrated. Maternal blood has a relatively large concentration of pgrogesterone which dimis\shes rapidly following delivery of the placenta. Presumably the compound exerts some effect in the maintenance of pregnancy. Its exact role has not been established.

Steroid concentrations in normal follicular fluid and ovarian cyst fluid from cows.

Summary. The following steroids were estimated in five samples of normal bovine follicular fluid, and in twenty-four samples of cyst fluid from cows with cystic ovaries: progesterone, 17α-hydroxyprogesterone, androstenedione, oestrone and oestradiol-17β. 20β-Hydroxypregn-4-en-3-one was also found in two samples of cyst fluid. No testosterone could be detected in any of the samples assayed. Oestradiol-17β was the major steroid present in all five samples of follicular fluid. The concentration of oestradiol-17β was significantly lower (P<0·01) in the cyst fluid. Many of the cyst fluid samples contained large amounts of progesterone, but little or no detectable 17α-hydroxyprogesterone, androstenedione, oestrone or oestradiol-17β. Histological examination of the cyst wall in a number of these cases showed atretic or luteinization changes. In one case where luteinization had occurred, 20β-hydroxypregn-4-en-3-one was also present in the cyst fluid. There was no obvious correlation between the behavioural characteristics of the 'cystic cows' and the nature or amount of the steroids present in the cyst fluid. Thus the steroid concentrations in nine 'cystic cows' with normal oestrous cycles did not differ significantly (P>0·05) from the concentrations in seven nymphomaniac cows. The absolute concentrations and relative amounts of the various steroids differed greatly, both between animals and within the same animal. It is therefore concluded that the cyst itself is not the primary defect in cystic ovarian disease. Both histologically and endocrinologically the cyst appears to be a degenerative structure. In the normal follicle, follicular growth and endocrine activity seem to accompany one another; in the cyst, on the other hand, follicular growth continues whilst endocrine activity is waning.

STEROIDS IN THE FOLLICULAR FLUID AND THE CORPUS LUTEUM OF THE MARE. A 'TWO-CELL TYPE' THEORY OF OVARIAN STEROID SYNTHESIS

SUMMARY A comparison has been made between the steroids present in equine follicular fluid and luteal tissue. Follicular fluid was found to contain progesterone, 17α-hydroxyprogesterone, androstenedione, epitestosterone, 19-norandrostenedione, oestrone, oestradiol-17β and 6α-hydroxyoestradiol-17β, in confirmation of previous studies. On the other hand, luteal tissue contained large amounts of progesterone and 20α-hydroxypregn-4-en-3-one, and a small quantity of 17α-hydroxyprogesterone. No C18 or C19 steroids could be detected. These findings are therefore interpreted as evidence in favour of a 'two-cell type' theory of steroid formation in the ovary. One type, possibly the theca interna cell, has the ability to convert progesterone into oestrogens; the other type, possibly the luteinized granulosa cell, has a diminished 17-hydroxylating ability and is unable to cleave the C21 side chain to make C18 and C19 steroids. However, it does have an active 20-reductase enzyme system present.