Oocyte maturation and ovulation in the Atlantic halibut, Hippoglossus hippoglossus (L.), examined using ultrasonography

High resolution ultrasound scanning was tested as a non-invasive technique for monitoring oocyte maturation and ovulalion in the Atlantic halibut Hippoglossus hippoglossus (L.). Female broodstock halibut were examined using a 7.5-Mhz linear ultrasound transducer, prior to and during spawning. Representative images of halibut ovaries are presented and discussed. Individual oocytes of spawning females were discernible during oocyte final maturation, due to the large increase in volume caused by water uptake. The yolky (vitellogenic) cocytes of pre-spawning fish were more reflective to ultrasound than hydrating oocytes. The resulting differences in depth of ultrasound penetration permitted easy distinction of pre-spawning from spawning females. In addition, short-term changes in the depth of ultrasound penetration were observed during repeated scanning of a spawning female, owing to progressive hydration of the oocyte batch destined for ovulation. Although of similar diameter, hydrating oocytes in the ovarian tissue could be discerned from eggs in the ovarian lumen because of the different acoustic properties of the surrounding media. The findings of the present study are considered promising for the future routine use of ultrasonography in halibut broodstock management.     

A comparison of a hybrid stubble turnip (cv. Appin) with other cruciferous catch crops for lamb fattening. 2. Animal performance and toxicological evaluation

Forage brassica catch crops can provide a valuable source of additional feed in the autumn when supplies of other feed are limited. Weaned lambs grazed either (A) a novel hybrid crop, stubble turnip cv. Appin, or (B) a sequence of crops consisting of fodder radish cv. Nerys, followed by forage rape cv. Canard. Forty, 60 or 80 g of crop DM per kg current live weight (LW) were allowed daily and the performance, intake and carcass yield of the lambs were monitored. Lamb LW gains were lower on treatment A (45, 65 and 72 g d^-1) than on B (78, 111 and 117 g d^-1) at the 40-, 60- and 80-g DM d^-1 allowances respectively. Intakes of forage crops, however, did not differ significantly, probably because the estimates of intake were made in the middle of each 14-d allocation period of the crops. The intake values are thus an indication of the potential intake when a relatively plentiful supply of food is available; they were 19·2, 17·2 and 18·2 g OM kg^-1 LW for treatment A and 16·2, 19·2 and 19·2 g OM kg^-1 LW treatment B at the 40-, 60- and 80-g DM d^-1 allowances respectively. Mild anaemia occurred in lambs feeding on both crops. Anaemia was more marked on treatment B, which was consistent with the higher concentrations of S-methyl cysteine sulphoxide (SMCO) but as the performance of animals was superior on treatment B, SMCO intake and anaemia are not thought to be the first or the most important factors in limiting animal performance. Goitrogenic changes in thyroid glands occurred on both crops. Mean weights of paired thyroid glands were 3·22, 4·28 and 4·21 g on treatment A and 3·29, 5·27 and 5·21 g on B at the 40-, 60- and 80-g DM d^-1 allowances respectively; the effects of both treatment and allowance were significant (P <0·21). Thiocyanate concentrations were higher on treatment A than B, indicating differing glucosinolate concentrations. While this was consistent with animal performance, it was not consistent with the weight of thyroid glands. However, the goitrogenic responses may have been complicated by the ingestion of soil iodine because very high faecal ash values were recorded. Thus, glucosinolates appear not to have affected lamb growth rate by their goitrogenic effect but the possibility remains that they may have influenced performance by other means.     

Expression and Localization of Vascular Endothelial Growth Factor and its Receptors in the Corpus Luteum During Oestrous Cycle in Water Buffaloes (Bubalus bubalis)

The aim of this study was to document the expression and localization of VEGF system comprising of VEGF isoforms (VEGF 120, VEGF 164 and VEGF 188) and their receptors (VEGFR1 and VEGFR2) in buffalo corpus luteum (CL) obtained from different stages of the oestrous cycle. Real‐time RT‐PCR (qPCR), Western blot and immunohistochemistry were applied to investigate mRNA expression, protein expression and localization of examined factors. In general, all the components of VEGF system (the VEGF isoforms and their receptors) were found in the water buffalo CL during the oestrous cycle. The mRNA as well as protein expression of VEGF system was highest during the early and mid‐luteal phase, which later steadily decreased (p < 0.05) after day 10 to reach the lowest level in regressed CL. As demonstrated by immunohistochemistry, VEGF protein was localized predominantly in luteal cells; however, VEGFR1 and VEGFR2 were localized in luteal cells as well as in endothelial cells. In conclusion, the dynamics of expression and localization of VEGF system in buffalo corpora lutea during the luteal phase were demonstrated in this study, indicating the possible role of VEGF system in the regulation of luteal angiogenesis and proliferation of luteal as well as endothelial cells through their non‐angiogenic function.     

INTRACRANIAL MAGNETIC RESONANCE IMAGING ARTIFACTS AND PSEUDOLESIONS IN DOGS AND CATS

Normal anatomic variation, study design, external factors, and tissue characteristics can all influence the manifestation of structures on magnetic resonance images (MRI). For the purpose of this review, imaging artifacts are considered to be nonpathologic abnormalities resulting from study design, intrinsic tissue characteristics, or external factors, while MRI pseudolesions are due to normal anatomic variation. Awareness of imaging artifacts and pseudolesions, as well as normal anatomic structures, is important when determining pathologic vs. normal or clinically insignificant abnormalities. The purpose of this report is to examine the literature to compile a review of selected artifacts and pseudolesions that are commonly encountered when imaging the canine and feline brain.