Spatial mapping shows that some African elephants use cognitive maps to navigate the core but not the periphery of their home ranges.

Strategies of navigation have been shown to play a critical role when animals revisit resource sites across large home ranges. The habitual route system appears to be a sufficient strategy for animals to navigate while avoiding the cognitive cost of traveling using the Euclidean map. We hypothesize that wild elephants travel more frequently using habitual routes to revisit resource sites as opposed to using the Euclidean map. To identify the elephants' habitual routes, we created a python script, which accounted for frequently used route segments that constituted the habitual routes. Results showed elephant navigation flexibility traveling at Kruger National Park landscape. Elephants shift strategies of navigation depend on the familiarity of their surroundings. In the core area of their home range, elephants traveled using the Euclidean map, but intraindividual differences showed that elephants were then converted to habitual routes when navigating within the less familiar periphery of their home range. These findings are analogous to the recent experimental results found in smaller mammals that showed that rats encode locations according to their familiarity with their surroundings. In addition, as recently observed in monkeys, intersections of habitual routes are important locations used by elephants when making navigation decisions. We found a strong association between intersections and new segment usage by elephants when they revisit resource sites, suggesting that intersection choice may contribute to the spatial representations elephants use when repeatedly revisiting resource sites.

Relationships between intrauterine infusion of N-acetylcysteine, equine endometrial pathology, neutrophil function, post-breeding therapy, and reproductive performance.

Persistent endometritis in the mare is associated with hypersecretion of mucus by endometrial epithelium and migration of neutrophils into the uterine lumen. This study examines the relationships between N-acetylcysteine (NAC), a mucolytic agent with anti-inflammatory properties, and endometrial architecture, serum neutrophil function, post-breeding therapy, and reproductive performance of NAC-treated mares in a clinical setting. In study 1, endometrial biopsies from mares receiving intrauterine saline (fertile-control, n = 6) or 3.3% NAC (fertile-treatment, n = 6; barren-treatment, n = 10) were evaluated by histology and image analysis. In study 2, phagocytic activity of serum-derived neutrophils was measured after adding 0.5% or 3% NAC. In study 3, pregnancy rates of repeat breeders (n = 44) receiving an intrauterine infusion of 3.3% NAC 24-36 hours before mating (group 1) was recorded, as was first cycle of the season pregnancy rates of reproductively normal mares (group 2, n = 85), and mares treated for bacterial endometritis the cycle before mating (group 3, n = 25). Intrauterine NAC did not adversely affect endometrial histology. Extracellular mucus thickness and staining intensity were reduced in fertile-treatment mares (P < 0.03). Neutrophil function was inhibited by 3% NAC solution, but not by 0.5% NAC (P < 0.05). In study 3, for groups 1, 2, and 3, respectively, the first-cycle pregnancy rates were 77%, 74%, and 56%, and early embryonic death rates were 15%, 13%, and 7%. In group 2 mares treated with uterine lavage and oxytocin post-mating, the pregnancy rate was 89% (39/44), whereas in mares treated with uterine lavage and 1 g ceftiofur, it was 60% (24/40). Of the oxytocin-treated mares, 18% (8/44) had ≥ 1 cm of intrauterine fluid or marked uterine edema, whereas 80% (32/40) of the antibiotic-treated mares did. In conclusion, intrauterine infusion of a 3.3% solution of NAC was not irritating and inhibited the oxidative burst of neutrophils. Repeat breeder mares, with evidence of mucus hypersecretion, but no uterine pathogens, when treated with NAC followed by post-mating uterine lavage and oxytocin (and in some cases intrauterine antibiotics), achieved a pregnancy rate of 77%.

Ameloblastic fibro-odontoma associated with a retained molar in an Oldenburg mare.

An 11-year-old Oldenburg mare presented with a 3-month history of weight loss and swelling of the posterior right mandible. Physical examination and radiographs showed a soft-tissue mass in the right mandible with foci of mineralization, periosteal proliferation, and a retained molar. The tumor increased in size over several weeks, and the mare was euthanized. On necropsy, a 24 cm × 15 cm × 15 cm firm, white mass had obliterated the posterior right mandible. The mass was multinodular with discrete clusters of blood-filled cystic spaces. Histologically, the mass was composed of neoplastic odontogenic epithelium and pulpal mesenchyme with an accumulation of eosinophilic material resembling dentin or enamel. Microscopic and immunohistochemical staining features of the neoplasm were most consistent with an ameloblastic fibro-odontoma.

Cytochemical and biochemical evidences for a complex tridimensional structure of the hamster zona pellucida.

Zona pellucida (ZP) is an extracellular matrix that surrounds eggs and pre-implantation embryos and is required for in vivo fertility. A key event in successful fertilization is sperm binding to the surface of the ZP. It has been previously described that the hamster sperm binds mainly the outer region of the ZP which corresponds to the porous region in contact with the cumulus cells. Using ultrastructural cytochemistry approaches with an antibody developed against porcine ZP, this study shows that the pig ZP shares epitopes with some rodent species like hamster, rat and mouse. In the hamster, these epitopes are located mainly in the outer region of the ZP of preovulatory and ovulated oocytes. By means of biochemical approaches it was demonstrated that 1) the antibody is specific for the native hamster ZP3, 2) four different bands with a molecular weight of 67, 60, 48 and 38 kDa after N-linked deglycosylation suggesting that the hamster ZP is formed by four proteins, and 3) the different composition observed in the outer region of the hamster ZP could be due to a specific supramolecular structure that makes some epitopes accessible for the antibodies. In summary, this study provides evidence that the different composition observed in the different regions of the ZP is mediated by a different organization of the components of the ZP produced during the oocyte maturation. This different organization could be responsible for the different sperm binding affinity observed for sperm to the outer region versus the inner region of the ZP.