Histogenesis of the ovine uterus

Reproductive tracts from fetal (d 55 to 150) and neonatal (d 9 to 3 mo) lambs were examined by light microscopy in order to describe ovine uterine histogenesis. Morphologically, d-55 and -60 fetal uteri were bipartite, though characteristic external cornual morphology was not apparent until d 100 to 110. Histologically, lumina of d-55 and -60 fetal uteri were tubular and smooth with no indication of caruncular or glandular areas. In d-90 to -100 fetal uteri, luminal clefts were visible along the mucosal surface and a band of eosinophilic, elongated, smooth muscle-like cells was distinguishable. By d 100 to 110, nodular and internodular areas were clearly defined as luminal clefts deepened. Expansion of deep internodular areas, parallel to the luminal nodular surface, progressed in fetal uteri from d 118 to 150. Slight invaginations along deep internodular areas were visible in d-135 fetal uteri and were regular features of d-150 fetal uteri. In contrast, shallow, slightly coiled simple tubular glands were visible in the endometrium of internodular (intercaruncular) areas in a d-9 neonatal uterus. Older neonatal uteri (d 26 to 3 mo) contained coiled tubular glands which extended to the myometrium. Data indicate a systematic pattern of ovine uterine histogenesis involving dynamic morphogenetic alterations, especially between d 80 to 130 of fetal life. The observation that uterine glands were absent in fetal uteri but present in neonatal uteri suggests that glandular induction must occur during the periparturiet/neonatal period.     

Ovine uterine morphogenesis: effects of age and progestin administration and withdrawal on neonatal endometrial development and DNA synthesis

To determine effects of age and administration and withdrawal of a synthetic progestin (P) on endometrial development and DNA synthesis, ewe lambs were ovariectomized on d 0 (birth) and assigned to one of four groups (n = three/group) that provided (by means of hemihysterectomy) the following uterine tissue types: 1) d 0 control, 2) d 13 control, 3) d 26 control, 4) d 13 after 13 d exposure to P (13P) and 5) d 26 after P exposure from d 0 to 13 (26P). Uterine tissues were processed for histology or explanted with [methyl-3 H] thymidine for autoradiography. Labeling index (LI) was determined for stroma and epithelium in caruncular and intercaruncular endometrial areas and for lumenal and glandular epithelium in uteri with glands. Endometrial glands were absent on d 0, evident at d 13 and well developed by d 26. Day 0 LI was greater (P less than .05) in caruncular than in intercaruncular areas, and greater in stromal than in epithelial tissues. Relationships were reversed in d 13 endometrium (day X endometrial area, P less than .07). Caruncular stromal LI was greater on d 0 than later (P less than .02), whereas intercaruncular epithelial LI was greater after d 0 (P less than .05), but decreased from d 13 to 26 (P less than .05). Glandular epithelial LI was higher on d 13 than on d 26 (P less than .03). Administration of P inhibited endometrial gland development and suppressed d 13P intercaruncular LI (P less than .05). Withdrawal of P was followed by endometrial gland development and increased (P less than .01) intercaruncular epithelial LI in d 26P uteri. Ovary-independent initiation of endometrial gland development involves age- and region-specific alterations in DNA synthesis and could involve negative control.     

Effect of recombinant porcine somatotropin on fetal and placental growth in gilts with reduced uterine capacity

Crowded uterine conditions were induced by unilateral hysterectomy-ovariectomy (UHO) in 42 gilts to determine the effect of recombinant porcine somatotropin on fetal and placental growth. Gilts were randomly assigned across three replicates to one of three treatments: Control (C; n = 14), daily injections of 1 mL saline from d 0 to 64 of gestation, Early (E; n = 12), 5 mg of rpST/d from d 0 to 30, followed by 1 mL saline from d 31 to 64, and Late (L; n = 16), 1 mL saline/d from d 0 to 29, followed by 5 mg of rpST/d from d 30 to 64 of gestation. Blood was collected from each gilt via jugular venipuncture at d 0 and every 15 d thereafter. Gilts were hysterectomized on d 65 of gestation. Length of placental attachment and fetal crown-rump length were measured. Placentas and fetuses were weighed. Placental length, wet weight, and dry weight were recorded. Treatment with rpST (either E or L) increased (P < 0.0001) maternal plasma IGF-I concentrations relative to controls. Treatment with rpST did not affect placental wet weight or placental DNA content. However, E and L treatments increased the percentage of placental protein (P = 0.01) and placental dry matter (P = 0.10) and increased contact area of uterine-placental interface (P = 0.01). Despite changes in placental composition and morphology, weights of fetuses collected from L-treated gilts did not differ from controls, whereas weights of fetuses collected from E-treated gilts tended to be less than controls (P < 0.06). Administration of rpST increased maternal IGF-I concentrations and placental surface area but failed to increase fetal growth in the UHO model. Therefore, mechanisms that are independent of maternal IGF-I or placental contact area may control early fetal growth under crowded uterine conditions.     

Isolation of bluetongue vaccine virus from infected sheep by direct inoculation onto tissue culture.

A technique is described by which the vaccine strain of bluetongue virus (BTVV) may be isolated from infected fetal, neonatal, and adult sheep tissues utilizing tissue culture. The data from these studies provides evidence that 1) BTVV can be readily isolated from infected fetal and newborn tissues by tissue culture, 2) mild treatment of tissues and utilization of lysed cells as inoculum an effective means of recovering vaccine virus, 3) BTVV can be isolated with equal efficacy from mononuclear fractions and from erythrocyte granulocyte fractions of viremic blood, and 5) the brain of fetal lambs and the spleen and liver of neonatal lambs appear to be the tissues from which vaccine can be consistently isolated.     

Post natal oestrogen administration stimulates precocious endometrial gland development in the horse

Reasons for performing study: Fillies completely devoid of endometrial glands (uterine gland knockout; UGKO) would make ideal experimental models in which to study the role of endometrial histotroph in embryogenesis and early fetal development in the mare. Hypothesis: Administration of a synthetic progestagen plus oestrogen to newborn filly foals and, thereafter, at regular intervals to age 6 months, would permanently suppress endometrial gland development. Methods: Nine half‐sister Thoroughbred filly foals were treated, in 3 groups, with: A) the weakly active progestagen, norgestomet, administered from birth to age 6 months, in subcutaneous implant form plus oestradiol valerate and norgestomet i.m. at fortnightly intervals; B) the strongly active oral progestagen, altrenogest, administered daily from birth to age 6 months plus fortnightly injections of oestradiol valerate and norgestomet; C) nothing (untreated controls). Endometrial biopsies were recovered from all fillies at ages 6 months and 2 years to assess the degree of endometrial gland morphogenesis and to determine immunohistochemically the presence or absence of oestrogen and progesterone receptors in the endometrial tissues. Results: Groups B and C showed no endometrial gland development, whereas Group A fillies showed a high degree of endometrial gland development, plus strong staining for both oestrogen and progesterone receptors at age 6 months. All 9 fillies showed full normal endometrial gland morphogenesis, development and function at age 2 years. Conclusions and relevance: While the administration of a strongly active progestagen over‐rode the actions of the concomitantly administered oestrogen and suppressed endometrial gland development during the period of administration, treatment with oestradiol valerate together with a weakly active progestagen, stimulated precocious endometrial gland development. Neither steroid was able to create the desired UGKO experimental model and all fillies showed normal endometrial gland development and fertility after puberty. Hence, ovarian oestrogen, not progesterone, appears to be the basic stimulus for endometrial gland morphogenesis in the horse.     

Neonatal estradiol exposure alters uterine morphology and endometrial transcriptional activity in prepubertal gilts

Porcine endometrial development between birth (postnatal day = PND 0) and PND 56 involves differentiation of glandular epithelium (GE) from luminal epithelium (LE) and estrogen receptor-alpha (ER) expression. Juvenile ER architecture evolves after birth, as stroma and nascent GE first express ER. Mature ER architecture is evident after PND 30, when stroma, GE and LE are ER-positive. When administered during discrete periods between PND 0 and 56, effects of estradiol-17beta valerate (EV) on the neonatal porcine uterus relate to endometrial ER architecture. Transient EV exposure from birth reduces embryo survival in pregnant adult gilts. Effects of EV, administered as juvenile endometrial ER architecture develops (P1, PND 0-13), or after mature ER architecture is established (P2, PND 42-55), were evaluated in uteri from gilts treated with corn oil or EV in P1 or P2 and hysterectomized on PND 100 without additional steroids (NSt), on PND 102 after EV on PND100-101 (EV2), or on PND 117 after EV2 followed by progesterone on PND 102-116 (EP). Neonatal EV reduced uterine weight (P < 0.02), size (P < 0.01), luminal protein content (P < 0.07), and percent incorporation of 3H-leucine into nondialyzable endometrial products in vitro (P < 0.01). Group (NSt, EV2, EP) -specific treatment effects detected for endometrial ER, progesterone receptor, uteroferrin, and/or retinol binding protein mRNA levels were frequently related to period (P1,P2). Results support the idea that estrogen-sensitive postnatal organizational events, including those defined, in part, by endometrial ER architecture, are likely components of genetic and epigenetic programs governing uterine morphogenesis and ontogeny of endometrial function in the pig.     

Spontaneous proliferative lesions and tumors of the uterus of captive African hedgehogs (Atelerix albiventris).

Fifteen captive female African hedgehogs (Atelerix albiventris), 3- to 5-yr-old, were diagnosed with proliferative uterine lesions (n = 28). Lesions were associated with vaginal bleeding in all cases, hematuria in 11 of 13 cases, and weight loss in 7 of 12 cases. Lesions were multiple in eight cases and single in seven cases. The lesions identified were 13 adenosarcomas, 7 endometrial stromal sarcomas, 6 endometrial polyps, 1 adenoleiomyosarcoma, and 1 adenoleiomyoma. In one animal with adenosarcoma, peritoneal seeding was detected at the time of hysterectomy. Mean survival time was 303 days (n = 10). Ovariohysterectomy allows prolonged survival of hedgehogs with uterine tumors.     

Effects of birth weight and postnatal nutrition on neonatal sheep: II. Skeletal muscle growth and development

This study investigated effects of birth weight and postnatal nutrition on growth and development of skeletal muscles in neonatal lambs. Low (L; mean +/- SD 2.289 +/- .341 kg, n = 28) and high (H; 4.840 +/- .446 kg, n = 20) birth weight male Suffolk x (Finnsheep x Dorset) lambs were individually reared on a liquid diet to grow rapidly (ad libitum fed, ADG 337 g, n = 20) or slowly (ADG 150 g, n = 20) from birth to live weights (LW) up to approximately 20 kg. At birth, weight of semitendinosus (ST) muscle in L lambs was 43% that in H lambs; aggregate weights of ST and seven other dissected muscles were similarly reduced. In ST muscle of L lambs, mass of DNA, RNA, and protein were also significantly reduced to levels 67, 60, and 34%, respectively, of those in H lambs. However, myofiber numbers of ST, tibialis caudalis, or soleus muscles did not differ between the L and H birth weight lambs and did not change during postnatal growth. During postnatal rearing, daily accretion rate of dissected muscle was lower in L than in H lambs. Accretion of muscle per kilogram of gain in empty body weight (EBW) was reduced in the slowly grown L lambs compared with their H counterparts, although the difference was less pronounced between the rapidly grown L and H lambs. Throughout the postnatal growth period, ST muscle of L lambs contained less DNA with a higher protein:DNA ratio at any given muscle weight than that of H lambs. Slowly grown lambs had heavier muscles at any given EBW than rapidly grown lambs. Content of DNA and protein:DNA ratio in ST muscle were unaffected by postnatal nutrition, but RNA content and RNA:DNA were greater and protein:RNA was lower at any given muscle weight in rapidly grown lambs. Results suggest that myofiber number in fetal sheep muscles is established before the presumed, negative effects of inadequate fetal nutrient supply on skeletal muscle growth and development become apparent. However, proliferation of myonuclei may be influenced by fetal nutrition in late pregnancy. Reduced myonuclei number in severely growth-retarded newborn lambs may limit the capacity for postnatal growth of skeletal muscles.     

Experimental infection of fetal and newborn Suffolk sheep with scrapie virus

Fetal (n = 21) and newborn (n = 7) Suffolk sheep were inoculated with scrapie virus isolated from other Suffolk sheep. Twenty fetuses, 76 to 109 days of gestational age, were inoculated IM in the neck through the uterine wall and were examined for virus 47 to 322 days later by mouse inoculation. Scrapie virus was not detected before 254 days of age; only traces of virus were detected in 3 of 7 lambs examined thereafter (2 at 254 days of age and 1 at 322 days of age). Virus was limited to the supra-pharyngeal, prescapular, and mesenteric lymph nodes. Seven lambs were inoculated into the palatine tonsils with scrapie virus as newborns (3 to 12 days old) and were examined for virus when they were 147 to 210 days old. Virus was not detected in the lymphoreticular tissues or terminal portion of ileum of any lamb. Failure to find scrapie virus in these lambs and in most lambs inoculated as fetuses might indicate few had became infected. However, if most lambs and fetuses had become infected, the long zero phase of the infection could have accounted for failure to find scrapie virus in many of them examined too soon after inoculation. The limited findings of this study indicate that efforts to demonstrate prenatal or neonatal transmission of scrapie by detecting virus are hampered by the slowness of its replication.     

Role of uteroferrin in placental iron transport in swine: relationship between uteroferrin levels and iron deposition in the conceptus during gestation

This study was to examine the relationship between uteroferrin and Fe, and Fe and Cu in the fetal pig. In Exp. 1, conceptus tissues and fluids were obtained on d 30, 45, 60, 75 and 90 of gestation for Fe and Cu analyses. In fetus minus liver, total Fe and Cu increased constantly between d 30 and 90, but Fe and Cu concentrations (microgram/g dry tissue) both decreased between d 30 and 45 and then remained relatively constant to d 90. For fetal liver, total Fe increased from d 30 (27 micrograms) to d 90 (3,222 micrograms), as did total Cu (14 micrograms on d 30 to 960 micrograms on d 90). Fetal liver Fe concentration (microgram/g dry tissue) decreased from d 30 (1,021) to d 60 (472) and then increased to d 90 (1,082), whereas Cu concentration increased between d 30 (537) and 60 (830) and then decreased between d 60 (471) and 90 (329). In allantoic fluid, both total Fe and Cu increased between d 30 and 60 and then decreased to d 90. Data from this study indicated a close temporal relationship between Fe and Cu in the fetal tissues and fluids examined. In Exp. 2, the relationship between Fe and uteroferrin in fetal tissues and fluids was studied. Uteroferrin, measured indirectly by acid phosphatase activity and Fe in fetal tissues and fluid underwent closely related temporal changes between d 30 and 112 of gestation. Changes in total Fe and Fe concentration during gestation were similar to those described for Exp. 1 in fetus minus liver, fetal liver and allantoic fluid. In addition, total Fe and Fe concentration in placental and endometrial tissues were analyzed. It was concluded that uteroferrin provides a major source of Fe in endometrial secretion and that it may be stored in placental and endometrial tissues. The relationship between Fe and Cu in conceptus tissues and erythropoiesis also is discussed.     

Removal of nocturnal secretion of melatonin fails to reduce antibody synthesis and interleukin-2 production of lambs.

Crossbred ewe and wether lambs were used to evaluate the effects of a normal, nocturnal elevation in the concentration of melatonin in the serum on immunological functions. The nocturnal elevation in melatonin was eliminated by exposing half the lambs to constant light (LL), whereas the remainder received a 12-h light, 12-h dark cycle (LD). Immune function was challenged by treating half the lambs in LL and half of the lambs in LD with dexamethasone (DEX; .04 mg/kg); the remainder of the lambs received only a saline vehicle (SAL). The resulting treatment combinations were designated LD+SAL (n = 5), LD+DEX (n = 5), LL+SAL (n = 5), and LL+DEX (n = 5). Lambs were stanchioned individually in environmental rooms; photoperiod treatments commenced on that day (d -14). Also on d -14, lambs were given 1 mg ovalbumin/lamb in adjuvant. Lambs were given a booster injection of .5 mg ovalbumin/lamb on d 0. Treatments with DEX and SAL also began on d 0 and were repeated every 48 h through d 14. Catheters were placed in the jugular vein of all lambs on d 12; samples of plasma and serum were collected hourly from 0800 on d 14 to 0800 on d 15; plasma was assayed for adrenocorticotropic hormone (ACTH) and serum was assayed for cortisol and melatonin. In addition, samples of serum obtained at 0800 on d 15 were used to evaluate antibody titers to ovalbumin. Samples of whole blood also were obtained at 0800 on d 15, and total and differential leukocyte numbers and production of interleukin-2 (IL-2) by lymphocytes were determined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of endocrine disrupting compounds on the pathology and oestrogen receptor alpha and beta distribution in the uterus and cervix of ewe lambs

A number of chemicals have been classed as endocrine disrupting compounds due to their ability to mimic the actions of endogenous hormones in vivo and in vitro. The objective of this experiment was to determine the pathological changes and oestrogen receptor (ER) distribution in the cervix and uterus of prepubertal ovariectomised ewe lambs following exposure to a range of compounds with a predominantly oestrogenic effect. Lambs were exposed to diethylstilbestrol (0.175 mg/kg biweekly), bisphenol-A (3.5mg/kg biweekly) or octylphenol (3.5mg/kg biweekly) for 6 weeks. Following sacrifice, uterine and cervical tissue pathology was assessed. The endometrial and myometrial areas were quantified and the distribution of ERalpha and ERbeta assessed by immunohistochemistry. No differences were observed between control and octylphenol-exposed lambs in uterine gross pathology and histopathology. Uteri from bisphenol-A- and diethylstilbestrol-exposed lambs were heavier than both control and octylphenol-exposed lambs. In the bisphenol-A-exposed lambs, endometrial oedema accounted for a significant increase in the endometrial cross-sectional area over the other groups. Uteri from animals exposed to diethylstilbestrol showed variable pathology including oedema and cellular proliferation. Keratinisation of the cervical epithelium was observed in both bisphenol-A- and diethylstilbestrol-exposed lambs. Exposure to diethylstilbestrol and bisphenol-A was associated with a diffuse intracellular distribution of ERalpha and ERbeta in the uterine endometrium. This was in addition to the strong cytoplasmic staining of uterine epithelial cells and nuclear staining of specific sub-epithelial cells observed in all groups. We conclude that a 6-week exposure of lambs to bisphenol-A and diethylstilbestrol altered the uterocervical environment and has the potential to disrupt subsequent reproductive function. Pathological changes could not be detected in the uterus or cervix of lambs exposed to octylphenol.     

Growth hormone, insulin and glucose concentrations in bovine fetal and maternal plasmas at several stages of gestation

For cows on d 137 (n = 6), 180 (n = 8), 226 (n = 9) and 250 (n = 5) of gestation (Exp. 1), concentrations of insulin and glucose were two- to three-fold less (P less than .01) in fetal venous plasma than in uterine arterial plasma. Concentrations of growth hormone, conversely, were 10- to 20-fold greater (P less than .01) in fetal venous than in uterine arterial plasma. Concentrations of insulin and glucose in maternal and fetal plasmas and concentrations of growth hormone in maternal plasma did not vary with stage of gestation. Concentrations of growth hormone in fetal venous plasma, however, were greater on d 226 and 250 than on d 137 and 180. For cows (n = 6) on d 198 of gestation (Exp. 2), concentrations of insulin and glucose in maternal and fetal plasmas and of growth hormone in maternal plasma remained relatively constant in samples collected every 30 min for 3 h. In contrast, growth hormone concentrations in fetal venous plasma were highly variable and appeared to be episodic, with pulses of 10 to 60 ng/ml in amplitude. No significant correlations were found among concentrations of insulin, glucose and growth hormone in fetal venous plasma. When samples were collected every 15 min for 4 h from cows (n = 5) on d 198 of gestation (Exp. 3), episodes of growth hormone in fetal venous plasma were irregular in amplitude and frequency.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased calf production in cattle selected for twin ovulations

The effects of increasing fetal numbers and their distribution between the left and right uterine horns on calf survival, calf BW at birth and weaning, gestation length, dystocia, and calf sex ratio were evaluated for single (n = 1,587), twin (n = 2,440), and triplet calves (n = 147) born to primiparous and multiparous females in the Twinner population at the US Meat Animal Research Center between 1994 and 2004. Cattle were distributed equally between the spring and fall breeding seasons. Fetal number and distribution in utero were determined by real-time ultrasonography at 40 to 70 d postbreeding. For cows and heifers combined, number of calves per parturition increased from 1.34 in 1994 to 1.56 in 2004. Gestation length was 6.8 d shorter (P < 0.01) for twins compared with singles (277.5 +/- 0.2 vs. 284.3 +/- 0.2 d) and 12.7 d shorter for triplets (271.6 +/- 0.8 d). Survival and BW of individual calves at birth decreased (P < 0.01) but total calf BW per dam increased (P < 0.01) as fetal number increased from single to triplet births. Twins resulting from bilateral twin ovulations had increased (P < 0.01) survival and BW at birth, a longer (P < 0.01) gestation length, and less (P < 0.01) dystocia than twins resulting from unilateral twin ovulations. Calf survival and BW at birth were 97.2 +/- 0.3% and 48.0 +/- 0.1 kg for singles, 92.0 +/- 0.4% and 39.0 +/- 0.2 kg for bilateral twins, 83.2 +/- 0.4% and 36.7 +/- 0.2 kg for unilateral twins, 73.8 +/- 1.4% and 30.6 +/- 0.7 kg for bilateral triplets, and 51.9 +/- 3.2% and 31.7 +/- 1.6 kg for unilateral triplets. Birth weight of single calves increased by 0.51 kg/d for each additional day of gestation length vs. 0.38 kg/d for individual twins. Calf BW at birth increased (P < 0.01) with age of dam from 2 to 4 yr. Twin and triplet births had a greater (P < 0.01) incidence of dystocia than single births. The ratio of male:female calves (0.52:0.48) at birth was not affected by type of birth. Postnatal calf survival was similar for all 3 types of birth. Total progeny BW at weaning for single, twin, and triplet births was 217.7 +/- 2.5, 328.3 +/- 3.2, and 378.4 +/- 15.0 kg, respectively (P < 0.01). Although most bovine females have the uterine capacity to gestate twin calves, decreased survival and BW of unilateral twins and of all triplets indicate that their growth and development may have been compromised by uterine crowding.     

Growth hormone at breeding modifies conceptus development and postnatal growth in sheep

Experiments were performed to determine the effects of components of the GH-IGF axis on conceptus development and postnatal growth in sheep. In Exp. 1, ewes received one of the following treatments: 1) sustained release GH at breeding, 2) sustained release GH at breeding and estradiol-17beta at d 5 and 6, 3) only estradiol-17beta at d 5 and 6, or 4) no treatment. Uteri were flushed on d 7, and flushings were analyzed for content of IGF-I. A single injection of sustained-release bovine GH at breeding increased IGF-I content in uterine luminal flushings compared with control ewes (P < 0.05). Treatment with estradiol-17beta on d 5 and 6 after breeding did not alter IGF-I content compared with control ewes, and it blocked the effect of GH on uterine luminal IGF-I content. In Exp. 2, sustained release GH or no treatment was administered at breeding, and gravid uteri were collected at d 25, 80, or 140 of gestation. On d 80, GH-treated ewes had smaller chorioallantoic weights (P < 0.05) and tended to have more efficient placentae (fetal weight/total placental weight; P = 0.052), with a higher percentage of placental weight as cotyledons (P = 0.068) compared with control ewes. In Exp. 3, ewes were treated with or without sustained release GH at progesterone withdrawal. Lambs from GH-treated ewes were heavier at birth (P < 0.05). Lambs from GH-treated ewes reared as singles, but not lambs reared as multiples, were heavier at 30, 60 (P < 0.05), and 75 d (P = 0.075) of age than lambs from control ewes. In conclusion, ewes treated with sustained-release GH at breeding developed smaller, more efficient placentas, and had larger lambs at birth.     

Repeated restraint and isolation stress alters adrenal and lymphocyte functions and some leukocyte differentiation antigens in lambs.

Lambs were used to evaluate the effect of repeated restraint and isolation stress (RIS) on secretion of cortisol, lymphocyte proliferative responses to mitogens, production of interleukin-2, and expression of leukocyte differentiation antigens. Differentiation antigens evaluated included cluster of differentiation antigens 2, 4, and 8 (CD2, CD4, and CD8, respectively); B cells; and major histocompatibility complex (MHC) class II, DQ, and DR. Lambs were assigned to either control (CON; n = 12) or to RIS treatment (n = 12) then were stanchioned in environmentally controlled rooms at 18 degrees C and constant light for 11 d before jugular vein catheters were inserted on d 0 of the experiment. On d 12, 13, and 14, lambs in the RIS treatment were removed to another location, restrained, and isolated from visual and tactile contact with other lambs for 6 h on each day. Following the 6-h stress treatment, lambs were returned to their home stanchions. The CON lambs remained in their stanchions. Samples of serum were obtained from all lambs, beginning before RIS (0 h) and at .5-h intervals until the completion of stress (6 h) on d 12 and 14. In addition, samples of whole blood were obtained at 0 and 6 h on d 12, 13, and 14 for evaluation of immune function characteristics. Fitted polynomial curves describing the cortisol response in RIS and CON lambs differed (P less than .005) on both d 12 and 14, reflecting the unmistakable increase in cortisol in response to the stressor.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adequacy of main uterine vein and the ovarian artery in the local venoarterial pathway for uterine-induced luteolysis in ewes.

The local uteroovarian pathway for uterine-induced luteolysis was studied in 34 ewes. Bilaterally ovulating ewes were used to study the role of the main uterine vein (uterine branch of uteroovarian vein) and unilaterally ovulating ewes were used to study the role of the ovarianartery. Surgical operation was done on day 7, 8, or 9 of diestrus and ewes were necropsied on day 20. In 4 bilaterally ovulating control ewes (unilaterally hysterectomized), mean weight of corpus luteum (CL) was less (P smaller than 0.05) on the side of the intact uterine horn (55 mg) than on the side of unilateral hysterectomy (548 mg). In 4 treated ewes (unilaterally hysterectomized and with surgical anastomosis of uterine vein from the intact side to the hysterectomized side), mean weight of CL on the hysterectomized side (153 mg) was less (P smaller than 0.05) than on the uterine-intact side (391 mg). The mean weight of CL on the hysterectomized side in the treated group was not significantly different from that of the uterine-intact side in the control group. Unilaterally ovulating ewes were randomized into 5 groups: (1) controls which were uterine intact, (2) controls in which a unilateral hysterectomy was done ipsilateral to CL, (3) unilateral hysterectomy done ipsilateral to CL and anastomosis of the ovarian branch of the ovarian artery on the uterine-intact side to the ovarian branch of the ovarian artery on the hysterectomized side, (4) controls in which unilateral hysterectomy was done contralateral to CL and the ovarian vascular pedicle on the uterine-intact side was isolated, and (5) unilateral hysterectomy done contralateral to CL, isolation of ovarian vascular pedicle on the uterine-intact side, and anastomosis of the ovarian branch of the ovarian artery on the unilaterally hysterectomized side to the ovarian branch of the ovarian artery on the uterine-intact side. Mean weight of CL was less (P smaller than 0.05) in groups 1 (56 mg), 3 (40 mg), and 4 (120 mg) than in groups 2 (408 mg) or 5 (473 mg). The mean weight of CL was not significantly different among groups 1, 3, and 4 or between groups 2 and 5. Results demonstrate that the local luteolytic effect of the uterus in ewes involves a venoarterial pathway and indicate that the main uterine vein is an adequate uterine outlet and the ovarian artery is an adequate ovarian inlet for the venoarterial pathway without the necessity of other possible concomitant local routes.     

Interrelationships among conceptus size, uterine protein secretion, fetal erythropoiesis, and uterine capacity

The interrelationships among d-11 conceptus size, d-105 placental weight, placental efficiency (the ability of the placenta to support fetal growth and development), fetal erythropoiesis, and uterine capacity were examined in 1/2 Meishan, 1/2 White crossbred gilts that were unilaterally ovariohysterectomized at 90 to 100 d of age. In Exp. 1, gilts were mated after at least one normal estrous cycle and then slaughtered at 105 d of gestation and number of fetuses and CL, placental weights, fetal weights, hematocrits, fetal plasma iron, and fetal plasma folate were measured. In Exp. 2, gilts were mated and plasma progesterone was measured on d 2 and 3 of gestation. On d 11, the length of the remaining uterine horn was recorded and the uterine horn was flushed with minimal essential medium. Number of CL, conceptus number, conceptus diameters, and total uterine flush retinol-binding protein (tRBP), acid phosphatase (tAP), and folate-binding protein (tFBP) were measured. Gilts were mated again and slaughtered at 105 d of pregnancy and the same traits measured in Group 1 were recorded. Plasma progesterone concentrations on d 2 and 3 were correlated with average conceptus diameter on d 11 (r = 0.60, P < 0.01, for each day). In contrast, tRBP (r = 0.49, P < 0.01), tAP (r = 0.53, P < 0.01), and tFBP (r = 0.51, P < 0.01) in uterine flushings on d 11 were only correlated with d-3 plasma progesterone concentrations. No correlations between d-11 average conceptus diameter or d-11 uterine length with d-105 uterine capacity were observed. Uterine capacity was negatively correlated with placental weight, fetal weight and fetal hematocrit (r = -0.36, P < 0.01; r = -0.44, P < 0.01; r = -0.32, P < 0.01; respectively). Hematocrits were correlated with fetal plasma iron (r = 0.50, P < 0.01) and folates (r = 0.44, P < 0.01). Hematocrit, plasma iron, and plasma folate were each correlated with residual fetal weights after adjusting for placental weight (a measure of placental efficiency), and accounted for 11% of the variation in this trait. These data suggest that conceptus diameter and uterine protein secretion on d 11 may be influenced by the onset of progesterone secretion by the CL, but do not support an influence of conceptus growth during early pregnancy on uterine capacity. These results also suggest that reducing placental and fetal weights will likely result in increased uterine capacity.     

Effects of exogenous somatotropin during early gestation on maternal performance, fetal growth, and compositional traits in pigs

The objective of this study was to determine the effects of maternal treatment with porcine somatotropin (pST) during early gestation on embryonic survival, fetal development, and internal environment for fetal growth. Sixty-two crossbred gilts received daily injections of either 3 mL of a placebo (control, n = 31) or 6 mg of pST (n = 31) from d 10 to 27 of gestation. Representative gilts were slaughtered on d 28, 37, and 62 of gestation. The remaining gilts were allowed to farrow. It was found that embryonic survival was not influenced by pST treatment (P > 0.10). However, pST affected the growth and composition of the maternal (endometrium) and fetal (chorion) parts of the placenta. Thus, endometrial RNA concentration tended to be increased by pST at d 37 (P = 0.15), and it was increased at d 62 (P < 0.05) of gestation, which is indicative of increased capacity for protein synthesis. At birth, placental chorion weight (P < 0.10) and contents of DM and protein (P < 0.05) were increased due to pST treatment, but no effects were detectable up to d 62 of gestation. Maternal pST treatment was effective at increasing nutrient supply to the embryo as suggested from elevated glucose concentrations in amniotic and allantoic fluids (P < 0.05) at d 28 of gestation. With regard to prenatal growth, embryonic DNA concentration was slightly elevated at d 28 (P < 0.10), but pST did not induce any changes in average embryonic, fetal, or neonatal weights. However, within litters, the birth weights of piglets in the 25% lowest weight group (LW) were increased by pST treatment vs control LW pigs (1,241+/-55 vs 1,099+/-59 g, P < 0.10). Thirty-eight neonates from 15 litters divided among the three weight groups were examined for body composition. The weight of the intestinal tract was increased above average after maternal pST treatment (P < 0.01). Additionally, the amounts of tissues such as bone (P = 0.12) and s.c. fat (P = 0.06), and of protein, fat (P = 0.10), and ash (P < 0.05) were increased, whereas the relative body composition remained unchanged by pST (P > 0.10). On average, muscle protein concentration was elevated due to pST (P < 0.01), and, in LW piglets, plasma IGF-I concentration was increased (P < 0.10). The results suggest that maternal somatotropin is a critical factor in early pregnancy capable of influencing placental nutrient transfer and placental growth. It thereby selectively improves the growth conditions for the smaller littermates.     

Leukotriene B4 in cows with normal calving, and in cows with retained fetal membranes and/or uterine subinvolution.

Two experiments were performed to study the relationship between leukotriene B4 (LTB4) synthesis and placental separation and uterine involution in the cow. In experiment I, the concentration and synthesis of LTB4 by caruncular tissue was lower in cows with retained fetal membranes (RFM cows, n = 11) than in cows that expelled the fetal membranes normally (NFM cows, n = 19). The presence of bacterial cell wall, especially of alpha-hemolytic streptococci and coagulase positive staphylococci enhanced LTB4 synthesis by allantochorion only in NFM cows. In the RFM group, Escherichia coli lipopolysaccharide decreased allantochorionic LTB4 synthesis. With caruncle, only epidermal growth factor increased LTB4 production in NFM cows. In experiment II, the caruncular and endometrial secretion of LTB4 was lower in cows with subuterine involution (SUI cows, n = 5) or cows with SUI and RFM (SUI+RFM cows, n = 4) than in cows with normal uterine involution (NUI cows, n = 8). This decrease was especially noticeable in the previously gravid horn. In the three uterine involution groups, there were no differences in LTB4 synthesis by caruncular tissue taken from the previously gravid horn. However, progesterone and a bacterial suspension of E. coli reduced the synthesis of LTB4. Estradiol had no effect on LTB4 synthesis at the end of the postpartum period. These results suggest that LTB4 may play an important role in both placental separation and uterine involution in cattle and LTB4 synthesis may be modulated by endocrine and bacterial factors.