The pattern of cervical penetration and the effect of topical treatment with prostaglandin and/or FSH and oxytocin on the depth of cervical penetration in the ewe during the peri-ovulatory period

Artificial insemination in sheep has two major limiting factors: the poor quality of frozen-thawed ram semen and the convoluted anatomy of the sheep cervix that does not allow transcervical passage of an inseminating catheter. It has been demonstrated that in the ewe during estrus, there is a degree of cervical relaxation mediated by ovarian and possibly gonadotrohic hormones, and we set out to investigate factors that might enhance cervical relaxation. Five experiments were conducted on ewes of different breeds to determine: 1) the pattern of cervical penetration during the periovulatory period in ewes of several breeds (Welsh Mountain, Île-de-France, Vendéenne, Romanov and Sarda); 2) the effect of the “ram effect” a socio-sexual stimulus, on cervical penetration; and 3) the effects of the intracervical administration of follicle-stimulating hormone (FSH), oxytocin and a prostaglandin E agonist (misoprostol) on the depth of cervical penetration during the periovulatory period. The results showed that during the periovulatory period in all breeds examined, there was increased penetration of the cervical canal (P < 0.05) by an inseminating catheter. Cervical penetration increased to a maximum 54 h after the removal of progestagen sponges and then gradually declined. Furthermore, the depth of cervical penetration but not its pattern, was affected (P < 0.05) by the breed of ewe. The maximum depth of cervical penetration was lower (P < 0.05) in the Vendéenne breed compared to the Île-de-France and Romanov breeds, which did not differ from one another. In the presence of rams, the depth of cervical penetration was increased at 48 and 54 h after removal of sponges (P < 0.05) and reduced at 72 h (P < 0.05). The local administration of hormones FSH, misoprostol (a PGE agonist) and oxytocin alone and in various combinations did not have any significant effect on the depth of cervical penetration during the periovulatory period. In conclusion, the natural relaxation of the cervix observed in ewes of several breeds occurs at a time during estrus, 54 h after the removal of progestagen sponges, which is the most suitable for artificial insemination. The effect was enhanced by the presence of a ram but not by the local intracervical administration of FSH, misoprostol and oxytocin even though oxytocin and PGE₂ are involved in cervical function. The time of maximum cervical penetration in the preovulatory period (54 h) coincides with high LH and estradiol concentrations suggesting they might be responsible for the relaxation of the cervix probably through an oxytocin-PGE mediated pathway.     

Intrinsic innervation of the ewe cervix and its variations during pregnancy

The course of the cholinergic and adrenergic nerve fibers in the cervix of the ewe was investigated in nonpregnant and pregnant animals using an acetylcholinesterase method and fluorescence histochemistry. Both technics in nonpregnant animals revealed a rich network of acetylcholinesterase and norepinephrine positive nerves around the blood vessels while the muscular innervation was moderately positive. Acetylcholinesterase fibers were also concentrated beneath the surface epithelium forming a plexus-like arrangement where isolated ganglion cells could be seen. At mid pregnancy cholinergic and adrenergic fibers decreased in density. The intensity of fluorescence was weaker and nerve fiber morphology was modified. We endeavoured to relate our findings to the problem of the neural control of contractions and the opening of the cervix of the ewe which is poorly supplied in nerve fibers, particularly at mid pregnancy.     

Differential responsiveness to oxytocin of the uterus and cervix in the ovariectomized ewe

The responsiveness of the uterus and cervix to oxytocin was compared in ovariectomized ewes fitted with intraparietal electrodes and treated with 17β-oestradiol. Before the injection of the steroid, only the cervix presented dose-related responses to oxytocin infusions. Within the 3–5-day period after oestrogen injection, both the uterus and cervix presented almost similar responsiveness to the neurohormonal agent. After the 6th day following oestrogen, the cervix remained reactive to the infusions of oxytocin, whereas the uterus failed to respond. It is suggested that the reactivity of the cervix, which is at least partially independent of oestrogen priming, may be due to oestrogen-independent oxytocin receptors present only in the cervix.     

Intrinsic innervation of the ewe cervix and its variations during pregnancy

Summary The course of the cholinergic and adrenergic nerve fibers in the cervix of the ewe was investigated in nonpregnant and pregnant animals using an acetylcholinesterase method and fluorescence histochemistry. Both technics in nonpregnant animals revealed a rich network of acetylcholinesterase and norepinephrin positive nerves around the blood vessels while the muscular innervation was moderately positive. Acetylcholinesterase fibers were also concentrated beneath the surface epithelium forming a plexuslike arrangement where isolated ganglion cells could be seen. At mid pregnancy cholinergic and adrenergic fibers decreased in density. The intensity of fluorescence was weaker and nerve fiber morphology was modified. We endeavoured to relate our findings to the problem of the neural control of contractions and the opening of the cervix of the ewe which is poorly supplied in nerve fibers, particularly at mid pregnancy.     

Influence of age and breed on the binding of oxygen to red blood cells of bovine calves

Gustin, P., B. Detry, A. Robert, M. L. Cao, F. Lessire, C. Cambier, V. Katz, M. Ansay, A. Frans, and T. Clerbaux.Influence of age and breed on the binding of oxygen to red bloodcells of bovine calves. J. Appl.Physiol. 82(3): 784-790, 1997.The influence ofsomatic growth and genetic selection on the whole blood oxygen equilibrium curve (OEC) was measured under standard conditions indouble-muscled and dairy calves during their first 3 mo of life.Crossbreed animals were also investigated. Hemoglobin,2,3-diphosphoglycerate (DPG), Cl, andP_i concentrations were alsomeasured. The percentage of fetal hemoglobin (HbF) was determined. Theinfluence of exogenous Cl, P_i, andpH on the OEC was also assessed. ThePO₂ at 50% hemoglobin saturation(P₅₀) increased during somaticgrowth, probably because of the increase in DPG recorded indouble-muscled neonates and to the progressive disappearance of HbF inboth breeds. The oxygen exchange fraction (OEF%) was used to assessthe combined influence of the OEC shift and OEC shape changes on bloodoxygen desaturation under standard conditions, when thePO₂ decreases within a physiologicalrange. The OEF% showed an increase during the first month, then astabilization. The effects of Cl, P_i, and pH in Friesian calves weresimilar as in adult cattle. Double-muscled neonates had alower P₅₀, OEF% values, and DPG concentrations and higher hemoglobin and Cl concentrations than Friesian neonates. The P_iconcentration and the percentage of HbF were similar in both breeds.The pH and the Cl concentration had significantly less effect on theOEC in double-muscled than in Friesian calves. Crossbreed animalsexhibited intermediate parameter values, between those recorded fordouble-muscled and Friesian calves. All differences between breedsprogressively disappeared during the first month. These data show thatblood function changes markedly in calves during the first month of life and that genetic selection can alter blood function.

     

The anatomy of the sheep cervix and its influence on the transcervical passage of an inseminating pipette into the uterine lumen

The anatomy of the sheep cervix is highly variable between animals and may explain the differing success of transcervical AI between individuals. This study aims to quantify the variation in cervical morphology between ewes and investigate the relationship between cervical anatomy and cervical penetration. Two series of reproductive tracts were collected. Series A: 132 adult anoestrous ewes, and series B: 165 cycling adult ewes and ewe lambs which were identified as luteal or non-luteal based on the presence of a corpus luteum. The morphology of the cervical external os was classified as slit, papilla, duckbill, flap or rose. An inseminating pipette was inserted into the lumen and the depth of penetration recorded. The cervix was opened longitudinally, its length recorded, the number of cervical rings counted and the arrangement of those rings graded. The maximum depth of cervical penetration was affected by cervical grade (series A: P=0.021; series B: P=0.037) and the stage of the oestrous cycle (P=0.008). Grade 1 cervices were more penetrable than grade 2, with grade 3 the least penetrable and non-luteal cervices could be penetrated further than luteal cervices. The distribution of os types differed with age, with rose types more common in adult ewes, and papilla os types more common in ewe lambs. These results indicate that the depth of cervical penetration is affected by the anatomy of the cervical lumen. Cervices with a less convoluted lumen (grade 1) were more penetrable. Non-luteal cervices are likely to have higher oestradiol concentrations than luteal, stimulating cervical relaxation and enabling deeper penetration. The difference in os types with age may be contributable to a morphological alteration at parturition.     

Influence of nutrition on ovulation rate in the ewe

The effect of nutrition on ovulation rate in the ewe is reviewed with particular reference to the role of protein and energy and the time of effect during the cycle. Ovulation rate is increased by both protein and energy. In the case of protein this was shown to be accompanied by increased plasma levels of FSH and androstenedione at about the time of luteolysis, while levels of LH were unaffected. Increased hepatic oxidative enzyme activity is proposed as a mechanism by which nutrient intake may influence ovulation rate.     

Neuropeptides in Alzheimer's disease: a postmortem study

The concentration of 5 neuropeptides, neurotensin (NT), somatostatin (SRIF), corticotropin-releasing factor (CRF), bombesin and thyrotropin-releasing hormone (TRH) was measured in 3 cerebrocortical areas and several subcortical regions in post-mortem brains obtained from patients with histologically verified Alzheimer's disease and from controls without neurological or psychiatric disorders using sensitive and specific radioimmunoassay procedures. In Alzheimer's disease, reductions in the concentration of SRIF and CRF were observed in frontal and temporal cortex. In addition, in Alzheimer's disease, SRIF was also reduced in concentration in the hypothalamus, whereas CRF concentrations were reduced in the caudate nucleus. Neurotensin was reduced in concentration in the amygdala in Alzheimer's disease. No alterations in TRH or bombesin/gastrin-releasing peptide were found. These findings provide further evidence for the pathological involvement of certain neuropeptide-containing neurons in Alzheimer's disease.     

Origin of improved depth penetration in dual‐axis optical coherence tomography: a Monte Carlo study

Recent studies have demonstrated that extended imaging depth can be achieved using dual‐axis optical coherence tomography (DA‐OCT). By illuminating and collecting at an oblique angle, multiple forward scattered photons from large probing depths are preferentially detected. However, the mechanism behind the enhancement of imaging depth needs further illumination. Here, the signal of a DA‐OCT system is studied using a Monte Carlo simulation. We modeled light transport in tissue and recorded the spatial and angular distribution of photons exiting the tissue surface. Results indicate that the spatial separation and offset angle created by the non‐telecentric scanning configuration promote the collection of more deeply propagating photons than conventional on‐axis OCT.      

The influence of age and breed on stallion semen

This study reports on the variation in semen quality and in spermatozoal and behavioral characteristics of 168 stallions representing 9 breeds and ranging in age from 2 to 26 yr. Semen samples were collected into an artificial vagina and the number of mounts and urethral pulsations per semen sample were recorded. Semen characteristics were examined for total volume, gel-free volume, gel volume, color score, mass activity, nonmotile spermatozoa, dead spermatozoa, semen density, spermatozoa concentration, total number of spermatozoa and semen pH. Morphological characteristics of the spermatozoa included abnormal heads, abnormal mid-pieces, abaxial mid-pieces, protoplasmic droplets and abnormal tails. Sources of variation were evaluated and the overall means calculated by least-squares analyses of variance for nonorthogonal data. The significance of breed effects and between stallion variability were estimated using mixed-model procedures. All semen characteristics with the exception of color and urethral pulsations had significant variation due to age. Semen quality (gel-free volume, sperm concentration, total sperm numbers and sperm abnormalities) was poorest in stallions under 3 yr of age and over 11 yr. Significant breed variation was apparent in most characteristics except for pH, semen color, abnormal midpieces and urethral pulsations. It is recommended that both the age and breed of stallion be taken into consideration when evaluating stallion semen.     

Effects of melatonin and plane of nutrition on mammary development in prepubertal Boutsiko mountain breed ewe lambs

The effects of melatonin (implants, M or no implants, C) and plane of nutrition (high, H or low, L) on mammary development and growth hormone (GH) concentrations were investigated in prepubertal Boutsiko mountain breed ewe lambs. Eighty female lambs were assigned to each of 4 treatments: ad libitum feeding control (HC), HM, LC and LM. The rearing treatments started and ended at mean ages of 63 and 160 d, respectively. Feed restriction resulted in a mean daily gain of 70.6% of the ad libitum-fed lambs during the experimental period. Melatonin (18 mg Regulin) was administered at 68 d of age (January 10) and replaced on March 1. Blood samples were collected from 10 lambs in each treatment group at the end of the experiment for GH measurements. At a mean age of 160 d, seven lambs from each treatment group were slaughtered and the udder was removed. One udder half was trimmed and the parenchyma and fat pad portions were kept for determination of deoxyribonucleic acid (DNA) content. Melatonin did not influence mammary development parameters, while the mass of parenchyma tended to be greater in lambs on low than high nutrition planes (P<0.10). Mean mammary parenchymal weight and DNA content were 25.1 and 29.2 g and 52.5 and 58.2 mg in high and low nutrition lambs, respectively. Mean plasma GH concentrations were not affected by melatonin treatment and were higher in low than high nutrition lambs (P<0.01). There were no correlations between mean plasma GH concentrations and parenchymal DNA content, or between mean daily weight gain and parenchyma (g), in contrast to those found in a previous experiment with lambs of the same breed but greater age at slaughter. The results suggest that a period of accelerated mammary development occurs later than 140 d of age in Boutsiko mountain breed ewe lambs.     

Effect of breed and age on sexual behaviour of rams

The objective of this study was to highlight the problems that arise during the reproduction between thin-tailed rams and fat-tailed ewes. At the same time, particular emphasis laid on the influence of sheep breed, sheep age, time after ram introduction and day of the ewe estrus cycle on ram and ewe sexual behaviour. Rams were subjected to sexual performance tests by being individually exposed to 12 ewes for 3 h daily, 19 consecutive days. The 16 rams of the experiment were separated according to their age (9 and 21 months old) and breed (Chios and Karagouniki), and the 96 ewes of Chios fat-tailed breed, were divided by age (9 and 21 months old). The main characteristics of courtship behaviour, like sniffing, nudging, flehmen response and following were recorded and studied in detail. Mature Chios rams, which were the only one with previous experience of Chios ewes, exhibited higher rates of sexual interest per ewe than the other rams (P < 0.05). On the other hand, rams sniffed and nudged more young than mature ewes (P < 0.05), probably due to the fact that young ewes did not express intense symptoms of estrus. Young rams exhibited substandard sexual interest towards mature ewes, when they first came in contact with them (P < 0.05). In general, Karagouniki thin-tailed rams exhibited reduced rates of mating behaviour when they courted with Chios fat-tailed ewes in comparison with Chios rams (P < 0.05). Moreover, as the time after ram introduction passed, the frequency and duration of sexual behaviour components decreased (P < 0.001). Finally, the effect of the day of the experiment was only significant in the case of sniffing, which increased during the first 2 days and then declined and stabilized (P < 0.01). As it was demonstrated, ram age and ram breed played a fundamental role in the exhibition of sexual interest elements.