Morphological characteristics of mule conceptuses during early development.

Hybrids between species are often infertile and extremely rare among mammals. Mules, i.e. crossing between the horse and the donkey, on the other hand are very common in agricultural and leisure practices due to their enhanced post-natal physical characteristics that is believed to occur for outbreeding or hybrid vigor. Since no reports are availableon the effects of hybrid vigor during early development, this study focused on characterizing the intrauterine development of mule conceptuses during critical embryo-to-fetus transition period. Nine embryos and fetuses of early gestation, obtained after artificial insemination and transcervical flushing, were evaluated by means of gross anatomy and histology and compared to data available for the equine. We found that some events, such as C-shape turning, apearence of branchial archs, limb and tail buds, formation of primary and secondary brain vesicles, heart compartmentalization, and development of somites, occurred slightly earlier in the mule. Nonetheless, no major differences were observed in other developmental features, suggesting similarities between the mule and the horse development. In conclusion, these data suggest that the effect of hybrid vigor is present during intrauterine development in the mule, at least with regard to its maternal parent.

Organogenesis of the Musculoskeletal System in Horse Embryos and Early Fetuses.

Musculoskeletal system development involves heterotypical inductive interactions between tendons, muscles, and cartilage and knowledge on organogenesis is required for clarification of its function. The aim of this study was to describe the organogenesis of horse musculoskeletal system between 21 and 105 days of gestation, using detailed macroscopic and histological analyses focusing on essential developmental steps. At day 21 of gestation the skin was translucid, but epithelial condensation and fibrocartilaginous tissues were observed on day 25 of pregnancy. Smooth muscle was seen in lymphatic and blood vessel walls and the beginning of cartilaginous chondrocranium was detected at day 30 of gestation. At day 45, typical chondroblasts and chondrocytes were observed and at day 55, mandibular processes expanded toward the ventral midline of the pharynx. At day 75, muscles became thicker and muscle fibers were seen developing in carpal and metacarpal joints with the beginning of the ossification process. At day 105, major muscle groups, similar to those seen in an adult equine, were observed. The caudal area of the nasal capsule and trabecular cartilages increased in size and became ossified, developing into the ethmoid bone. The presence of nasal, frontal, parietal, and occipital bones was observed. In conclusion, novel features of equine musculoskeletal system development have been described here and each process was linked with an early musculoskeletal event. Data presented herein will facilitate a better understanding of the equine muscular system organogenesis and aid in the detection of congenital deformities. Anat Rec, 299:722-729, 2016. © 2016 Wiley Periodicals, Inc.

Campilobacteriose genital bovina: ocorrência nos estados do Rio de Janeiro e Minas Gerais / Genital bovine campilobacteriosis: occurrence in Rio de Janeiro and Minas Gerais states

Para verificar a ocorrência de campilobacteriose genital bovina, em rebanhos de bovinos leiteiros do Rio de Janeiro e Minas Gerais, realizou-se a prova de muco-aglutinaçäo lenta para as fêmeas, e o isolamento bacteriológico para os machos. Dos 248 animais examinados durante o período de 1996 a dezembro de 1997, constataram-se 71 animais positivos (28,63 por cento), 33 suspeitos (13,31 por cento) e 144 negativos (58,06 por cento), provenientes de 21 propriedades visitadas nos estados do Rio de Janeiro e Minas Gerais, sendo diagnosticada a campilobacteriose em 20 propriedades (95,2 por cento). A campilobacteriose provavelmente contribuiu para a baixa eficiência reprodutiva verificada nos rebanhos examinados.