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Biomedical subjects

B N Day

Publications and source records attributed to B N Day.

16 recordsLinked to original sources
PubMed1992

Immunocytochemical analysis of the association of bovine oviduct-specific glycoproteins with early embryos.

The bovine oviductal epithelium synthesizes and secretes a class of oviduct-specific glycoproteins that is present in the luminal fluid when fertilization and early embryonic development occur. The objective of this study was to determine if these characterized glycoproteins become associated with oviductal embryos. Ovarian ova and oviductal embryos were recovered from super-ovulated cows at 72 h after onset of estrus. Eggs were fixed in 3% paraformaldehyde-1% glutaraldehyde and subsequently embedded in Lowicryl K4M. Sections (1 micron) were processed for peroxidase-antiperoxidase immunocytochemistry. Immunolabeling was not detected in any region of ovarian ova. Oviductal embryos, regardless of cleavage stage, exhibited immunoperoxidase staining localized within their zona pellucidae. Sections (100 nm) obtained from a 4- and an 8-cell embryo were also subjected to colloidal gold immunoelectron microscopy to determine conclusively the subcellular distribution of the oviduct-specific glycoproteins. Gold particles were distributed uniformly throughout the width of the zona pellucida. Also, immunoreactivity was observed associated with flocculent material in the perivitelline space and with the vitelline membrane. These results indicate that the bovine oviduct-specific secretory glycoproteins become associated with oviductal embryos. This association may be biologically important to the developing embryo.

Animals↗
PubMed1992

Influence of ovarian steroids on relaxin-induced uterine growth in ovariectomized gilts.

This study examined the influence of ovarian steroids on the uterotropic actions of relaxin (RLX) in ovariectomized prepubertal gilts. Ovariectomized gilts received (im) corn oil (CO), estradiol benzoate (EB), or EB and progesterone (P) for 0-16 days. Steroid administration was patterned to approximate the plasma concentrations of endogenous ovarian steroids observed during 1) the follicular phase (EB), 2) luteal phase (EB+P), and 3) early pregnancy (EB+P+EB). Half of each group also received PBS or 0.5 mg RLX every 6 h for 54 h, coinciding with the final 2 days of the experimental period. After hysterectomy, uterine tissues were analyzed for water, dry matter, protein, DNA, glycosaminoglycans (GAGs), and collagen contents. Administration of EB or P increased uterine weight 5- to 6-fold, but no differences were observed between EB+P- and EB+P+EB-treated gilts. Cotreatment with RLX enhanced steroid-induced uterine growth 40-70%, and RLX stimulated growth in CO- and EB+CO control gilts 2- to 3-fold. The water content of uterine tissues was greater in EB-, EB+P-, and EB+P+EB-treated gilts than in their respective controls, and this response was augmented by RLX in all treatment groups. Administration of steroids stimulated a 4- to 5-fold increase in uterine dry weight compared to that in controls, with responses not differing between EB+P- and EB+P+EB-treated gilts. In all groups, RLX increased uterine dry weight. Protein and DNA contents of uterine tissue increased with steroid treatment, but neither variable differed between EB+P- and EB+P+EB-treated gilts. Administration of RLX, alone or in combination with steroids, increased protein and DNA contents of uterine tissues. The tissue content of GAGs increased in response to steroids, and coadministration of RLX did not alter this response. Although the uterine tissue concentration of collagen was reduced in steroid- and RLX-treated gilts, the collagen content of the uterus was not affected by the various treatments. The results of this study indicate that RLX is a potent stimulator of uterine growth under a variety of steroidal environments. RLX- or steroid-induced uterine growth was manifest by increased water, dry matter, protein, and DNA and GAG contents, but the uterine content of collagen was not affected. The overall growth-promoting effects of EB and the stimulation of DNA accretion by RLX were not observed when gilts were cotreated with P.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1991

Effect of cell-free synchronous uterine flushings and microsurgery on the development of porcine embryos in vitro.

Experiment I was designed to determine if cell-free synchronous uterine flushings contain an embryotoxic substance that is normally screened by the intact zona pellucida. Sixty 4-cell embryos were allocated to three treatment groups: 1) control embryos (n = 20) were cultured in Modified Kreb's Ringer Bicarbonate medium + 10% bovine calf serum (mKRB-BCS), 2) UF embryos (n = 20) were cultured in 80% mKRB-BCS + 20% sterile dialyzed uterine flushings (UF), 3) MicroUF embryos (n = 20) received a microsurgical incision in the zona pellucida and were cultured in 80% mKRB-BCS + 20% UF. Following 72 h in culture at 37 degrees C under a 90% N2, 5% CO2, and 5% O2 atmosphere, the number of nuclei/embryo and the incidence of protrusion of the trophoblast through the zona pellucida (PTZ) were recorded. Addition of UF had no effect on embryo development. A greater (P less than .005) proportion of MicroUF embryos exhibited PTZ as compared to UF and control embryos. Experiment II was devised to further characterize the occurrence of PTZ in Micro porcine embryos. Thirty-three 4- to 10-cell embryos and 14 morulae were distributed across two treatments: 1) control embryos (n = 16 and 6, respectively) were cultured as described in Experiment I; and 2) micro embryos were treated similarly to MicroUF embryos in Experiment I but were cultured in mKRB-BCS only. At the onset of PTZ, embryos were immediately fixed and examined. The proportion of embryos exhibiting PTZ was greater (P less than .007) for Micro versus control embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The transition from maternal to zygotic control of development occurs during the 4-cell stage in the domestic pig, Sus scrofa: quantitative and qualitative aspects of protein synthesis.

A study was conducted to identify the embryonic stage when the zygotic genome begins to direct development and to characterize protein synthesis in pig oocytes and embryos. Reproductive tracts of gilts were flushed to obtain unfertilized oocytes (UFO), zygotes (Z), 2-, 4-, and 8-cell embryos, compact morulae (M), initial blastocysts (IB), blastocysts (B), and hatched blastocysts (HB). Pig eggs and embryos were cultured in medium containing 1 microM L-[35S]methionine and evaluated for amino acid uptake, incorporation of the radiolabel into protein, and qualitative changes in protein profiles specific to each cleavage stage. Unfertilized oocytes sequestered 65.7 fmol methionine/4 h/embryo. Uptake of methionine decreased (p less than 0.05) from the Z (49.4), 2-cell (41.8), and 4-cell (37.6) embryonic stages to the M (8.97 fmol/4 h/embryo) stage. This downward trend was reversed at the IB, B, and HB stages when uptake increased to 37.3, 50.3, and 84.2 fmol/4 h/embryo, respectively. Incorporation of methionine into protein followed a similar pattern, being relatively higher in the UFO (21.0), Z (20.5), and 2-cell stages (16.0); decreased (p less than 0.05) at the 4-cell (6.67), 8-cell (6.84), and M (6.16) stages; and increased (p less than 0.05) at the IB (28.0), B (41.5), and HB (69.6 fmol/4 h/embryo) stages. Differences in protein profiles were observed for UFO, Z, 4-cell, and M stages using lysates of single embryos, one-dimensional SDS-PAGE, and fluorography.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Episodic secretion of gonadotrophins and ovarian steroids in jugular and utero-ovarian vein plasma during the follicular phase of the oestrous cycle in gilts.

Blood samples were collected simultaneously from the jugular and utero-ovarian veins of 13 gilts from Days 11 through 16 of the oestrous cycle. A luteolytic dose (10 mg) of PGF-2 alpha was given on Day 12 to facilitate the natural occurrence of luteolysis and standardize the associated decrease in concentrations of progesterone. The mean interval from PGF to oestrus was 5.5 +/- 0.7 days (mean oestrous cycle length = 17.5 +/- 0.7 days). Mean concentrations, pulse amplitudes and pulse frequencies of oestradiol and progesterone were greater (P less than 0.05) in the utero-ovarian than jugular vein. Secretory profiles of LH and FSH were similar (P greater than 0.05) in plasma collected simultaneously from both veins. Based on these data, temporal relationships among hormonal patterns of FSH and LH in the jugular vein and oestradiol and progesterone in the utero-ovarian vein were examined. Concentrations of progesterone declined (P less than 0.05) between Days 12 and 14, while all secretory variables for oestradiol increased (P less than 0.05) from Day 12 through 16 of the oestrous cycle. The pulsatile secretion of FSH remained relatively constant during the experiment. However, both pulse amplitude and mean concentration tended (P less than 0.2) to be lower on Day 16 compared with Day 12. The episodic secretion of LH shifted from a pattern characterized by high-amplitude, low-frequency pulses to one dominated by numerous pulses of diminishing magnitude between Days 13 and 14. From Days 14 to 16 of the oestrous cycle, 91% of all oestradiol pulses were temporally associated with gonadotrophin pulses composed of both FSH and LH episodes. However, pulses of oestradiol (52%) not associated with an episode of LH and/or FSH were observed on Days 12 and 13. These data demonstrate that during the follicular phase of the pig oestrous cycle substantial oestradiol production occurred coincident with luteolysis and before the shift in the episodic secretion of LH. The pool of follicles which ovulated was probably the source of this early increase in the secretion of oestradiol. Therefore, we propose that factors in addition to FSH and LH are involved in the initial selection of follicles destined to ovulate during the early stages of the follicular phase of the pig oestrous cycle. In contrast, high-frequency, low-amplitude pulses composed of LH and FSH were the predominant endocrine signal associated with oestradiol secretion during the second half of the oestrous cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

The effects of recombinant porcine somatotropin on reproductive function in gilts treated during the finishing phase.

The objective of this study was to determine the effects of recombinant porcine somatotropin (rpST) treatment during the finishing phase on subsequent reproductive function in crossbred gilts. Forty gilts weighing 50 kg and housed in a swine finishing facility were randomly assigned to control or rpST treatment. Four control and four rpST-treated gilts were allotted per pen. Twenty rpST-treated gilts received 6 mg of rpST.gilt-1.d-1 in 1 ml of buffered carrier and 20 control gilts received 1 ml of buffered carrier.gilt-1.d-1. Injections were administered daily at 1400 in the extensor muscle of the neck. All gilts received an 18% CP diet containing 1.2% lysine. Treatment was terminated when the average weight in each pen reached 110 kg. Gilts treated with rpST gained more weight (P less than .05) than control gilts (59.8 +/- 1.0 vs 53.5 +/- 1.0 kg). Age at puberty was not different (rpST, 182.2 +/- 3.3; control 181.4 +/- 3.1 d). Prior treatment with rpST did not significantly affect length of estrus (rpST, 1.9 +/- .1; control, 1.8 +/- .1 d) or estrous cycle length (rpST, 20.6 +/- .4; control, 20.4 +/- .4 d). Ovulation rates at second estrus were similar for rpST gilts (15.1 +/- .5) and control gilts (14.4 +/- .5). More embryos (P = .10) were recovered on d 9 to 12 of gestation from rpST-treated gilts than from control gilts (13.1 +/- .9 vs 10.7 +/- .9).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Reproductive performance of sows treated with a combination of pregnant mare's serum gonadotropin and human chorionic gonadotropin at weaning in the summer.

During the summer and fall of 1987, sows from eight herds in three states were assigned randomly to receive either a combination of 400 IU of pregnant mare's serum gonadotropin with 200 IU of hCG (P.G. 600) or no treatment at weaning. A treatment x parity interaction was observed for days to first estrus after treatment and percentage anestrus (percentage of sows not achieving estrus within 10 d after weaning). Relative to primiparous control sows, primiparous sows given P.G. 600 expressed estrus sooner (P less than .02) after weaning (6.0 vs 7.8 +/- .6 d) and exhibited less (P less than .02) postweaning anestrus (15.6 vs 29.2 +/- 4.0%). Second parity sows that received P.G. 600 showed estrus sooner (P less than .06) than second-parity control sows (4.7 vs 6.4 +/- .7 d). Days to first estrus after treatment did not differ between groups for parity-three and older sows, and percentage anestrus was not different between treatments for parity-two and older sows. The herd X treatment interaction was significant for percentage recycled (percentage of successfully mated sows that returned to estrus), subsequent farrowing rate, and subsequent number of pigs born dead. Number of pigs born alive was lower for sows treated with P.G. 600 than for control sows (10.55 vs 10.10 +/- .18; P less than .02). In summary, treatment of sows weaned in the summer and fall with P.G. 600 had decreased days to postweaning estrus in parity-one and -two sows and reduced frequency of postweaning anestrus in primiparous sows.

Anestrus↗
PubMed1990

Alterations in gonadotropin secretion and ovarian function in prepubertal gilts by elevated environmental temperature.

The effect of chronic exposure to elevated environmental temperature on gonadotropin secretion and ovarian function was studied in prepubertal gilts. Gilts were maintained under control (15.6 degrees C) or elevated temperature (33.3 degrees C) conditions from 150 to 180 days of age. Endocrine and ovarian responses to bilateral (BLO), unilateral (ULO), and sham ovariectomy were evaluated between 175 and 180 days of age. During the 96-h sampling period after BLO, plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were suppressed in heat-stressed females. Similarly, elevated temperatures abolished the transient rise in FSH and subsequent follicular growth normally associated with ULO. In contrast, environmental treatment had no effect on the secretion of FSH and LH after sham ovariectomy, yet the number of small follicles was lower in gilts exposed to elevated temperatures than in females maintained under control conditions. These results indicate that a chronic exposure to elevated environmental temperature during pubertal development diminished the ability of the hypothalamo-hypophyseal axis to secrete FSH and LH, which had physiological consequences on follicular growth. When provided an appropriate stimulus (ULO), an acute period of FSH secretion and subsequent development of follicles failed to occur in females exposed to elevated temperatures. Consequently, we propose that delayed puberty in gilts during periods of elevated environmental temperatures is due, in part, to a diminished capacity for gonadotropin secretion.

Animals↗
PubMed1979

Control of estrus in gilts with a progestogen.

Two trials were conducted to evaluate the effectiveness of a synthetic progestogen, allyl trenbolone, for control of estrus and ovulation in gilts. Estrus was effectively synchronized with 33 of 38 gilts exhibiting estrus 2 to 7 days after last progestogen feeding. There was no effect on fertilization rate in gilts free of ovarian abnormalities. Ovulation rate was higher in gilts fed the progestogen in both Trial 1 (P less than .01) and Trial 2 (P less than .10). Progestogen treatment caused an increase (P less than .01) in the incidence of cystic follicles which resulted in a decrease (P less than .01) in conception rate in Trial 1.

Animals↗
PubMed1976

Embryo transfer in pigs: a method for introducing genetic material into primary specific-pathogen-free herds.

Fifty-five embryos were transferred from 4 Duroc donor sows into 4 crossbred recipient gilts. The embryo survival rate was 66%; 53% of eggs ovulated by donors were represented by live pigs at term. Three of the litters were obtained by hysterectomy of the recipients and introduced into a primary specific-pathogen-free herd, thereby saving the donor sows for subsequent use. Embryo transfer provided a method for exploiting the genetic potential of superior females.

Animals↗