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Mimas has a high eccentricity and an anomalously high physical libration like its neighbor, Enceladus, but does not appear to have a geologically active surface. We investigate Mimas' interior with a technique that infers spatial variations in tidal heating from its global shape. To account for its hydrostatic shape, we find Mimas' normalized moment of inertia is 0.375 ± 0.0025, indicating a relatively undifferentiated world. Its remaining topography is consistent with a ∼30 km thick conductive ice shell in Airy isostasy atop a weakly convecting ∼30 km thick layer that itself mantles a ∼140 km radius ice‐rock interior. The convective shell's density must be closer to the interior density to satisfy our moment of inertia and provide a denser compensating layer for Airy isostasy. This ice‐rock interior is elongated along the Mimas‐Saturn axis, which can match Mimas' observed physical libration without appealing to an ocean. The inferred ice shell thickness variations indicate a high obliquity (≈1.7°). We suggest that the obliquity damped rapidly, after which topography froze in when internal heat was conducted out of Mimas quicker than isostatic ice shell thickness variations could relax. We speculate on several possible explanations for this transient high obliquity, including excitation by ring‐forming material following the recent tidal disruption of an eccentric satellite. We cannot rule out a young Mimantean ocean, but our inferred moment of inertia favors a Mimas that was solid when it experienced a period of high obliquity, did not significantly melt during a recent resonance with Enceladus, and is solid today. While Saturn's moon Mimas appears to have an ancient surface covered in craters, it has a highly elliptical orbit, as well as a wobble in its rotation that is higher than expected for a solid, spherically symmetric moon. This wobble could indicate Mimas has either an ocean or an elongated core. To investigate the possibility of an ocean, we examine differences from sphericity in Mimas' shape. Some of this shape is from Mimas' tidal bulge and rotational flattening. Assuming the rest is topography due to differences in heat that arise due to tidal forces, we can relate Mimas' topography to its tidal heating pattern. Because a moon's tidal heating pattern is influenced by its interior structure, we can then make inferences on Mimas' interior. What we find indicates that the tidal heating conditions that produced Mimas' shape indicate its spin pole was once tilted much higher than one would expect at present day. This could have occurred long ago, after which the topography froze in when Mimas rapidly cooled. The tidal heating pattern we infer also indicates that Mimas did not have an ocean at the time of this strong tidal heating, and likely remains solid to this day. We infer spatial variations in tidal heating and ice‐shell thickness from Mimas' non‐hydrostatic shapeOur preferred Mimas interior has no sub‐surface ocean but requires high obliquity tides in Mimas' pastMimas' past obliquity may have been excited by gravitational interaction with an inward‐migrating debris disk that formed Saturn's rings We infer spatial variations in tidal heating and ice‐shell thickness from Mimas' non‐hydrostatic shape Our preferred Mimas interior has no sub‐surface ocean but requires high obliquity tides in Mimas' past Mimas' past obliquity may have been excited by gravitational interaction with an inward‐migrating debris disk that formed Saturn's rings

The objective of this study was to elucidate the phenotypic relationships between docility and first-service AI conception rate in heifers. Data (n= 337) collected from 3 cooperator herds in Kansas at the start of synchronization protocol included exit velocity (EV), chute score (CS), fecal cortisol (FC), and blood serum cortisol (BC). Data were analyzed using logistic regression with 30-d pregnancy rate as the dependent variable. The model included the fixed effect of contemporary group and the covariates FC, BC, EV, CS, BW, and age. Correlation coefficients were calculated between all continuous traits. Pregnancy rate ranged from 34% to 60% between herds. Blood cortisol positively correlated with EV (r= 0.22, P< 0.01), negatively correlated with age (r= −0.12, P< 0.03), and tended to be negatively correlated with BW (r= −0.10, P= 0.09). Exit velocity was positively correlated with CS (r= 0.24, P< 0.01) and negatively correlated with BW (r= −0.15, P< 0.01) and age (r= −0.12, P< 0.03). Chute score negatively correlated with age (r= −0.14, P< 0.01), and age and BW were moderately positively correlated (r= 0.42, P< 0.01), as expected. Older, heavier animals generally had better temperament, as indicated by lower BC, EV, and CS. The power of our test could detect no significant predictors of 30-d pregnancy for the combined data from all ranches. When the data were divided by ranch, CS (P< 0.03) and BW (P< 0.01) were both significant predictors for 30-d pregnancy for ranch 1. The odds ratio estimate for CS has an inverse relationship with pregnancy, meaning that a 1-unit increase in average CS will reduce the probability of pregnancy at ranch 1 by 48.1%. Weight also has a negative impact on pregnancy because a 1-kg increase in BW will decrease the probability of pregnancy by 2.2%. Fertility is a complex trait that depends on many factors; our data suggest that docility is 1 factor that warrants further investigation.

Prepubertal gifts were treated with 750 IU pregnant mare serum gonadotropin (PMSG) and 72 h later with 500 IU human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Laparotomies were carried out on groups of four or five gilts 24, 48, 72, 76, 88, 96, 102, or 108 h after PMSG treatment, and follicular fluid (FF) was aspirated from developing follicles. In most cases FF collected from each ovary of individual gilts was pooled, and the concentration of estrone (E1), estradiol-17β(E2), androstenedione (A), testosterone + 5α-dihydrotestosterone (T+DHT), and progesterone (P) in each sample was determined by radioimmunoassay. The FF concentrations of A and T+DHT remained relatively constant throughout the preovulatory development of the Graafian follicle. The FF concentrations of E1, E2, and P increased until 72 h after administration of PMSG. Following hCG treatment the FF concentrations of E1and E2declined rapidly to levels below those observed 24 h after PMSG treatment and remained at these levels, whereas the levels of P remained relatively constant until 30 h after hCG was given and then increased sharply. Resumption of meiosis was first evident by 16 h after injection of hCG and coincided with the decline in FF estrogen concentrations. These results indicate that the microenvironment of the Graafian follicle during preovulatory growth and development undergoes an orderly sequence of changes in steroid hormone concentrations which appear to be modulated by exposure of the developing follicle to gonadotropic stimuli.

Experiments were carried out to determine the effects of inhibition of synthesis of prostaglandins by indomethacin on ovulation, oocyte maturation, luteinization and luteal function in prepubertal gilts treated with PMSG and hCG to induce follicular growth and ovulation. Indomethacin suppressed ovulation and the preovulatory rise in follicular fluid levels of prostaglandin E and prostaglandin F when administered at 20, 24 or 32 h after hCG injection. Oocyte maturation was not inhibited by indomethacin but progressive degeneration of the cumulus cell mass surrounding the oocyte occurred with time. Unruptured follicles in indomethacin treated animals progressively increased in size, blood and fibrin filled the central cavity and there was thickening and extreme vasodilatation of the thecal sheath; lutein cells lining the cavity appeared normal. Groups of PMSG/hCG treated gilts, treated with indomethacin 20 or 32 h after hCG treatment, had plasma progesterone profiles which were similar to those of untreated controls and indicated normal luteal function. These results support the hypothesis that ovarian synthesis of prostaglandin is a prerequisite in the sequence of events leading to follicle rupture and ovulation but do not implicate prostaglandins in oocyte maturation, or in development of normal luteal function.

It is found that the planar area bounded by the graphs of y = mx, y = 2mx, and y = 1/x, in the first quadrant remains invariant for all values of the parameter m > 0. This unexpected result is extended to the case y = 1/xp for the boundary curve and a function A(m,p) of two free variables is created. Geometric characteristics of the surface A(m,p) are studied to initiate an n-ologue in the calculus teaching community.

Prepubertal gilts were treated with 750 IU pregnant mares’ serum gonadotropin (PMSG) and 72 h later with 500 IU human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Dispersed granulosa (GC) and theca interna (TIC) cells were prepared by microdissection and enzymatic digestion from follicles obtained 36, 72 and 108 h after PMSG treatment and incubated for up to 6 h in a chemically defined medium in the presence or absence of arachidonic acid, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and indomethacin. Production of prostaglandin E2(PGE) and prostaglandin F2α(PGF) was measured by radioimmunoassay. Both GC and TIC had the capacity to produce prostaglandins, with production by each cell type increasing markedly with follicular maturation. PGE was the major prostaglandin produced by both cellular compartments. Only PGE production by GC was consistently enhanced by addition of arachidonic acid to the incubation medium. Neither cell type was responsive to FSH and LH in vitro. Indomethacin inhibited the production of PGE and PGF by both cell types. These results provide convincing evidence for an intrafollicular source of prostaglandins and indicate that both cellular compartments contribute significantly to the increased production of prostaglandins associated with follicular rupture.

A synthetic decapeptide gonadotrophin releasinghormone (GnRH)5was used to induce ovulation in PMSG-primed, prepuberal gilts weighing 55 to 75 kilograms. Five of 10 animals injected with 1.0 mg GnRH ovulated within 48 hr. after the injection. However, single injectionsof 0.5 mg or less GnRH failed to induce ovulation. The route of GnRH administration, intravenous or intramuscular, did not appear to influence the rate of ovulation or number of gilts ovulating. GnRH-treated gilts that ovulated showed a peak serum LH concentration of 1.7 to 3.6 ng/ml within 24 hr. of treatment.

Oocytes recovered from abattoir-derived ovaries were exposed to a cryoprotectant solution (DAP213: 2 M DMSO, 1 M acetamide, 3 M propanediol, and 10% fetal calf serum in tissue culture medium 199) for less than 20 s and vitrified either at the germinal vesicle (GV) stage or after maturation in vitro (IVM). Survival was assessed by fertilization and culture in vitro to the blastocyst stage. To identify ultrastructural changes, some of the vitrified oocytes that were morphologically normal after thawing were immediately processed for transmission electron microscopy after DAP213 removal. Cleavage rates for vitrified IVM oocytes were 4.5 and 6.7% using one-step and three-step cryoprotectant dilution procedures, respectively. Four (3%) oocytes developed to the eight-cell stage with the three-step procedure, but none formed blastocysts. None of the GV oocytes cleaved, while 66.7% (78/117) of controls developed to the two-cell stage and 19.2% (15/78) of those became blastocysts. Vitrification induced profound ultrastructural modifications in microvilli, mitochondria, vesicle formation, and the ooplasm of GV oocytes, whereas these structures were generally better preserved in IVM oocytes. The integrity of cell organelles was relatively better maintained following the three-step than after the one-step procedure in both GV and IVM oocytes. Changes in the zona pellucida (ZP) of IVM oocytes due to vitrification were associated with fewer cortical granules in the ooplasm. Since previous work showed that short-term exposure to DAP213 did not cause ZP alterations in IVM oocytes, these findings suggest that ZP damage due to low temperatures may result from the premature release of cortical granules. Copyright 1995, 1999 Academic Press

The follicular fluid is an important milieu for the growing and maturing oocyte and granulosa cells. In this study we investigated: (1) the properties of gonadotrophin-binding sites in the supernatant fraction of porcine follicular fluid (pFF) and compared them with those of membrane-bound receptors, and (2) the relative changes that occur in pFF and granulosa cell receptor-binding activity following hormone priming of gilts. 125I-Labelled human chorionic gonadotrophin (hCG) and 125I-labelled ovine FSH (oFSH) binding to particulate and supernatant fractions of pFF were hormone-specific and saturable. The concentration of 125I-labelled hCG-binding sites was roughly 50-fold higher in particulate than in supernatant fractions of pFF. However, 30–40% of the total 125I-labelled hCG-binding activity in pFF was present in the supernatant fraction of commercial batches of pFF. 125I-Labelled oFSH binding to pFF membranes was markedly higher than to supernatant fractions. Binding of 125I-labelled hCG and 125I-labelled oFSH to granulosa cells and supernatants of pFF showed a time-dependent variation in response to hormone priming. The results suggest that gonadotrophin-binding sites in the supernatant fraction of pFF have properties similar to those of their membrane-bound counterparts. 125I-Labelled hCG-binding activity in the supernatant fraction of pFF was shown to be more stable than detergent-solubilized LH/hCG receptors, even in glycerol-preserved preparations. Based on a number of criteria, we have speculated that pFF may have components which may be similar in structure to the extracellular domain of the LH/hCG receptor.Journal of Endocrinology(1990) 124,485–494

Abstract. Inhibin-like bioactivity (IBA) was assessed by bioassay in the follicular fluid, ovarian venous plasma, and peripheral plasma of immature gilts in which follicular development had been synchronized by administration of pregnant mare serum gonadotropin (PMSG) and hCG. IBA was detectable in the pooled follicular fluid of control animals, but the concentration as well as the total content increased markedly with the growth of the follicle induced by PMSG. About 36–72 h after PMSG treatment, IBA was found consistently in the venous plasma of both ovaries, although in controls as well as after ovulation (i.e. +48 h after hCG) IBA was not detected. The amount of IBA exiting the ovary by way of venous circulation was only a small fraction (< 1%) of the total activity calculated to be in each ovary at a given time. IBA was undetectable in the peripheral plasma at any sampling time. On the basis of these results we could speculate that other routes of entry of inhibin into peripheral circulation may exist in the immature pig and/or that the predominant action of IBA might be within the follicle itself.

Plasminogen, plasmin, and plasminogen activator (PA) activities and PA and PA inhibitor (PAI) contents were measured in granulosa (GC) and theca interna cell extracts and follicular fluid (FF) obtained from preovulatory follicles of prepubertal gilts treated with eCG and hCG to induce follicular growth and ovulation. Plasmin activity in FF increased just before the time of expected ovulation. This increase was not attributable to changes in plasminogen levels, which remained relatively constant during preovulatory follicular development. The increase in follicular plasmin levels was associated with significant (p< 0.01) increases in PA activity and content and decreases in PAI content in GC and FF. Western blot analysis suggested that follicular PA activity was represented principally by two forms of tissue type PA (t-PA) each with a pI of 7.8 and with molecular masses of 72,000 and 78,000 daltons, respectively. Two PA-PAI complexes of 126,000 and 130,000 daltons were observed. These complexes were partially dissociated with nucleophilic agents into two t-PA-like forms and a 52,000-dalton PAI protein with a pI of 4.8. Biochemical characteristics of the PAI protein suggest that it belongs to the same class of inhibitors as bovine and human PAI-1. These data indicate that rupture of the porcine ovarian follicle is temporally associated with a net increase in PA activity and an increase in plasmin activity. The increase in PA activity appears to be regulated by changes in PA and PAI content.

Summary.Fifteen sows were assigned to three groups of five each, according to gestational age (109 days, 114 days or labour). Two fetuses per sow were chosen at random, and amnion, allantochorion, amniochorion, amniotic fluid and fetal urine were collected. Tissues were enzymatically dispersed and incubated for 1, 2, 3 or 4 h and the prostaglandin (PG) content of the supernatant medium was measured by radioimmunoassay. In general, all placental cell types produced at least three times more prostaglandin E (PGE) and 6-keto-PGF1αthan PGF. Production did not vary across gestational age, except that production of 6-keto-PGF1αwas lower in cells collected during labour, resulting in a relative increase in PGF and PGE. Amniochorion cells had a lower de novocapacity to synthesize PG than did allantochorion or amniochorion, whereas treatment of allantochorion with preterm amniotic fluid, preterm or term fetal urine resulted in increased PG output. These results demonstrate that porcine placental cells can synthesize and metabolize prostaglandin in late gestation but suggest that their capacity to produce PGI2(as measured by 6-keto-PGF1α) is lower than for other prostaglandins during labour.Keywords:prostaglandin; placenta; pig; fetal fluids

Demi-embryos (produced by destroying 1 or 2 blastomeres of 2- or 4-cell embryos, respectively) and intact mouse embryos were cultured to the blastocyst stage, stored at - 5°C for 48 h, then cultured for 24 h and transferred into pseudopregnant recipients. Supercooled storage did not impair the developmental potential of whole or demi-embryos in vitro, nor was there a difference between whole and demi-embryos with respect to growth in vitro. Similarly, there was no effect of supercooling on development of intact or demi embryos after transfer into pseudopregnant recipient mice, but fewer recipients of demi-embryos remained pregnant (P &lt; 0.05). This was considered to be partly due to the lesser ability of demi-embryos to maintain luteal function and establish pregnancy. Copyright 1993, 1999 Academic Press

Summary.Dispersed granulosa and theca interna cells were recovered from follicles of prepubertal gilts at 36, 72 and 108 h after treatment with 750 i.u. PMSG, followed 72 h later with 500 i.u. hCG to stimulate follicular growth and ovulation. In the absence of aromatizable substrate, theca interna cells produced substantially more oestrogen than did granulosa cells. Oestrogen production was increased markedly in the presence of androstenedione and testosterone in granulosa cells but only to a limited extent in theca interna cells. The ability of both cellular compartments to produce oestrogen increased up to 72 h with androstenedione being the preferred substrate. Oestrogen production by the two cell types incubated together was greater than the sum produced when incubated alone. Theca interna cells were the principal source of androgen, predominantly androstenedione. Thecal androgen production increased with follicular development and was enhanced by addition of pregnenolone or by LH 36 and 72 h after PMSG treatment. The ability of granulosa and thecal cells to produce progesterone increased with follicular development and addition of pregnenolone. After exposure of developing follicles to hCG in vivo, both cell types lost their ability to produce oestrogen. Thecal cells continued to produce androgen and progesterone but no longer responded to LH in vitro. These studies indicate that several functional changes in the steroidogenic abilities of the granulosa and theca interna compartments occur during follicular maturation.

Northern analysis was used to identify relaxin gene expression in ovaries of prepubertal pigs primed with pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (hCG). The cellular distribution of relaxin transcript in the developing follicle was localized by in-situ hybridization histochemistry. Three probes complementary to non-overlapping regions of the porcine prorelaxin molecule were used to identify relaxin gene expression in ovarian follicular tissue collected 0, 48, 60, 72 and 84 h after treatment with PMSG/hCG. A 1 kb transcript was detected in ovarian extracts of prepubertal gilts from 48 to 84 h after PMSG stimulation. This corresponds to the molecular size of the relaxin transcript reported in the pregnant sow ovary. Relaxin mRNA levels increased in ovaries from animals 48 through 84 h after PMSG. In-situ hybridization showed that the site of relaxin synthesis was the theca interna layer of the developing follicle. Relaxin mRNA was not observed in other follicular cell types, in small or atretic follicles or in follicles from unstimulated animals. The distribution and relative concentration of relaxin mRNA showed a good correlation with in-vitro production and immunohistochemical localization of relaxin previously reported in the developing pig follicle. The presence of both protein and mRNA for relaxin in the growing follicle supports a role for relaxin as a local regulator of ovarian function.

Northern analysis and in-situ hybridization were used to follow the development of relaxin gene expression in the newly forming corpus luteum (CL) after ovulation and throughout luteal development. Alkaline phosphatase (AP) was used as a marker of theca-derived lutein cells and the relationship between AP-positive and relaxin mRNA-containing cells was assessed. Ovaries from prepubertal pigs treated with pregnant mares serum gonadotrophin (PMSG)/human chorionic gonadotrophin (hCG) were collected during the periovulatory period and at various times during 19 days after ovulation. In addition, CL from cyclic pigs on days 10 and 16 were used to monitor relaxin gene expression in small and large luteal cells. Northern analysis revealed that relaxin gene expression increased with CL development in the PMSG/hCG-treated pig, reaching maximal levels at around day 14 post-ovulation. Thereafter, as the CL regressed, the level of relaxin mRNA declined. In CL from cyclic pigs at day 10 of the cycle, only small luteal cells expressed relaxin mRNA. However, by day 16 of the cycle, large luteal cells were the source of relaxin gene expression. In-situ hybridization studies revealed that in the early CL (up to 30 h post-ovulation), the relaxin gene transcript was observed in cells along the margins of the CL and in the core of the infolding follicle wall corresponding to the AP-positive, luteinized theca cell layer. As luteinization progressed, the theca and granulosa cell layers could no longer be distinguished morphologically (from 54 h after ovulation until day 9). However, the pattern of relaxin hybridization persisted along the periphery in bands of cells penetrating the CL, and coincided with areas of AP staining, indicating that the theca lutein cells were the site of relaxin gene expression. At day 14, relaxin hybridization and AP staining were distributed throughout the luteal tissue. With CL regression both AP staining and relaxin hybridization declined. This pattern of relaxin hybridization in the CL of the gonadotrophin-primed pig was identical to that observed in cyclic pigs on days 10 and 16 of the cycle. These findings indicate that theca interna cells retain their ability to express the relaxin gene following ovulation and luteinization. In the early CL, the small theca-derived lutein cells are the source of relaxin transcript. However, as the CL becomes fully differentiated, the large granulosa-derived lutein cells acquire the capacity to express the relaxin message.