Search

The properties of cervical–vaginal fluid are under strict hormonal control: and in mammals in which semen is deposited in the anterior vagina, changes produced in these properties can result in a lower or higher resistance to sperm motion. The aim of this study was to determine whether the structural organization of bovine vaginal fluid is related to its rheological properties. Vaginal fluid samples were collected from 41 cows at oestrus: 20 at the middle of oestrus (between 8 and 12 h after starting) and 21 at the end of oestrus (between 18 and 22 h). Flow behaviour was determined using a viscosimeter, and the ultrastructural analysis was performed by scanning electron microscopy. Six samples showed newtonian behaviour: three collected at the middle and three collected at the end of oestrus. Newtonian samples had dense and compact matrices arranged as membranes with rough, irregular surfaces, and sparse, thin filaments (< 150 nm). Non‐newtonian samples collected at the end of oestrus (n= 18) had a higher (P =0.016) consistency index (K= 944 ± 229 mPa.sn) than those collected at the middle of oestrus (n= 17; K= 237 ± 84 mPa.sn). Thick filaments (> 700 nm) that were either randomly arranged with thinner filaments forming a mesh or heavily cross‐linked by thin filaments (50–150 nm) were observed in all non‐newtonian samples collected at the end of oestrus, while medium‐diameter filaments (between 200 and 500 nm) forming loose networks were observed in non‐newtonian samples collected at the middle of oestrus. These findings indicate a close relationship between the molecular organization of the structural elements of bovine vaginal fluid and its rheological behaviour. Vaginal fluid dramatically reduces its mechanical barrier effect during the course of oestrus but always appears to maintain its three‐dimensional filamentous structure. The images of vaginal fluid showing newtonian behaviour would appear to support previous results, suggesting that this property may be related to bovine infertility.

Glutathione (γ-glutamyl-cysteinyl-glycine; GSH) is a ubiquitous intracellular free thiol that improves development of the male pronucleus at fertilisation and has also been implicated in promoting the development of preimplantation embryos. The objective of this study was to evaluate the effects of adding GSH or cysteine to the in vitro maturation medium on intracellular GSH amounts after in vitro maturation and fertilisation of prepubertal goat oocytes. Oocytes were matured in TCM199 medium supplemented with 10% bovine fetal serum, 1 mg/ml 17β-estradiol, 10 μg/ml o-FSH, 10 μg/ml LH and 50 mg/ml gentamicin. In vitro maturation medium was completed with two independent treatments: GSH at different concentrations (0, 0.25, 0.50 and 1.00 mM) and L-cysteine at different concentrations (0, 150, 300, 600 and 900 μM). After 27 h of culture at 38.5 °C in 5% CO2 in air, the nuclear stage was evaluated. Simultaneously, another sample of oocytes was frozen and the intracellular GSH level was evaluated with spectrophotometric methodology. Oocytes were inseminated with fresh semen (2-3 × 106 sperm/ml) in TALP medium supplemented with 1 mg/ml hypotaurine. Oocytes were fixed at 20 h post-insemination to evaluate the in vitro fertilisation. Oocytes matured in 1.00 mM GSH-supplemented medium exhibited higher amounts of intracellular GSH (3.23 pmol per oocyte). The percentage of normal fertilisation (17-27%) was similar for the treatment groups. In conclusion, the addition of 1.00 mM GSH to the maturation medium could be a useful method for increasing the intracellular GSH levels of prepubertal goat oocytes. However, this increase was not associated with a higher normal fertilisation rate of prepubertal goat oocytes.

Anestrus is common during the postpartum period in high-producing dairy cows. In a previous investigation, we were able to diagnose persistent follicles of 8 to 12 mm in anestrous cows. This report describes 2 consecutive studies. The objectives of the first were to 1) assess the association of persistent follicles with anestrus; and 2) evaluate 2 therapeutic treatments. In the second study, we compared the effectiveness of the best treatment established in Study 1 with the Ovsynch protocol. For Study 1, anestrous cows were considered to have a persistent follicle if it was possible to observe a single follicular structure > 8 mm in the absence of a corpus luteum or a cyst in 2 ultrasonographic examinations performed at an interval of 7 d. At diagnosis (Day 0), cows were assigned to 1 of 3 treatment groups. Cows in Group GnRH/PGF (n=17) were treated with 100 μg GnRH im, and 25 mg PGF2αim on Day 14. Cows in Group PRID (n=18) were fitted with a progesterone releasing intravaginal device (PRID, containing 1.55 g of progesterone) for 9 d and were given 100 μg GnRH im at the time of PRID insertion, and 25 mg PGF2αim on Day 7. Cows in Group Control (n=18) received no treatment. The animals were inseminated at observed estrus and were monitored weekly by ultrasonography until AI or 5 weeks from diagnosis. Blood samples were also collected on a weekly basis for progesterone determination. The mean size of persistent follicles on Day 0 was 9.4 ± 0.04 mm. Progesterone levels were < 0.2 ng/mL during the first 35 d in 16 of 18 Control cows. Cows in the PRID group showed a lower persistent follicle rate (16.7% < 70.6% < 88.9%; P < 0.0001; PRID vs GnRH/PGF vs Control, respectively); a higher estrus detection rate (83.3% > 29.4% > 11.1%; P < 0.0001) and a higher pregnancy rate (27.8% > 5.9% > 0%; P = 0.02). For the second study, 145 cows with persistent follicles were randomly assigned to 1 of 2 treatment groups: cows in Group Ovsynch (n=73) were treated with 100 μg GnRH im on Day 0, 25 mg PGF2αim on Day 7, and 100 μm GnRH im 32 h later. Cows in this group were inseminated 16 to 20 h after the second GnRH dose (Ovsynch protocol). Cows in Group PRID (n=72) were treated as those in the PRID group of Study 1, and were inseminated 56 h after PRID removal. Cows in the PRID group showed a higher ovulation rate (84.8% > 8.2%; P < 0.0001); a higher pregnancy rate (34.2% > 4.1%; P < 0.0001) and lower follicular persistence rate (22.2% < 63%; P < 0.0001) than those in Ovsynch. Our results indicate that persistent follicles affect cyclic ovarian function in lactating dairy cows. Cows with persistent follicles can be successfully synchronized and time inseminated using progesterone, GnRH and PGF2α but show a limited response to treatment with GnRH plus PGF2α.

The present study describes the structural components of the bovine vaginal fluid at estrus by scanning electron microscopy (SEM) following critical point‐ and freezedrying preparation procedures. Confocal scanning laser microscopy (CLSM) was also used to evaluate the structural integrity of samples, and a control sample was assessed by adding sperm to the vaginal fluid. Samples were collected from 10 cows at the time of artificial insemination, prepared for SEM by using critical point‐ and freeze‐drying procedures, gold coated, and observed by SEM. Mesh size and filament thickness were measured with an image analyzer. Of the 10 samples processed, 4 were considered altered following critical point drying. Compaction and lack of filaments were observed in these samples. A small area of one sample showed a honey comb‐like structure when freeze drying was used. Nonoriented filaments with different thicknesses and with a network‐like structure were observed throughout the remainder of the samples. Filaments throughout all samples were also observed by CSLM. After critical point drying, the mesh area ranged from 0.8 to 101.4 μm2; the minor axis from 0.7 to 10.8 μm; and filament thickness from 40 to 442 nm. Using freeze drying, the mesh area ranged from 0.9 to 493.8 μm2; the minor axis from 0.7 to 27.5 μm; and filament thickness from 40 to 800 nm. When samples were freeze dried, mesh values were similar to the interstrand channels observed by CSLM. In sperm‐vaginal fluid samples, following critical point‐ or freeze‐drying procedures, spermatozoa were oriented randomly in the vaginal fluid and did not seem to alter filamentous structure. Our data suggest that the freeze‐drying procedure better preserves the true structural dimensions of the vaginal fluid. Furthermore, the filamentous structure of the vaginal fluid does not appear to impede sperm transport.

Summary The arterial and venous systems of the neck and heads of a dicephalic iniodymic monosomic cat are described. In the arterial system, an anomalous lingual branch of the right external carotid formed a large subhyoid arch, extending to the midline between both heads, giving off branches supplying the medial aspect of both heads and terminating in two medial internal carotid arteries each for the right or left head. This vessel was considered as an anomalous supernumerary common carotid artery. In the venous system, each lingual branch of linguofacial veins united and formed an anomalous venous arch. It received rostrally a long midline vein running between both heads and connecting with the medial internal jugular system. This vein received tributaries from the left and right heads and was considered as a supernumerary jugular vein. From these observations, and those of others in the literature, it can tentatively be suggested that, in congenital cephalic duplications in domestic mammals, the arterial blood supply for the medial aspect of both heads tends to come from the lingual branch of the external carotid artery, with an unexplained prevailing contribution of the right external carotid system. Two different venous patterns have been observed. In animal especies exhibiting a hyoid venous arch, such as carnivores, a midline supernumerary external jugular vein draining at the anomalous junction between lingual veins of both heads is formed, whilst in animals lacking a constant hyoid venous arch, such as ruminants, an asymmetrical supernumerary external jugular vein draining into the right “normal” external jugular vein has been repeatedly described.