Gender differences in the rat corpus callosum: An ultrastructure study

Sexual dimorphism exists at all levels of the nervous system, from genetic, anatomical and system levels. The sexual dimorphism in the axonal content of the corpus callosum (CC) has always been controversial; hence, the aim of this study was to analyse the differences in total, myelinated and unmyelinated axons density of various regions of the CC between male and female rats. To assess that, six pairs of adult male and female rats were perfused and the CC was removed and sectioned. Four sections from different subregions of the corpus callosum that represent the genu, anterior body, posterior body, and splenium, were stained, and electron microscopic images were captured using stereological guidelines. Later, the axons density for each subregion was calculated and compared between males and females. The findings of the present study indicated region‐specific differences in the myelinated, unmyelinated or the ratio of myelinated/total axons in the CC between male and female rats.     

Agenesis of the vulva in a Maltese dog

Vulvar agenesis in a four-month-old Maltese dog is described. Urinary incontinence and dysuria were the main clinical signs. The morphology of the urogenital system was assessed with contrast radiography. Through episiostomy a perineal stoma, resembling a vulva, was created, resulting in complete resolution of the clinical signs.     

Anencephaly in calves

Anencephaly occurred in four calves and was characterized by cranioschisis, absence of the diencephalon with the cerebral hemispheres and rostral midbrain, various forms of eye defects, and relatively normal development of caudal brain stem, cerebellum and spinal cord. Amorphous dysplastic vestiges of the cerebral tissue protruded into the cranial defects. Morphologic features varied but were essentially similar. The cerebellum was absent in one case. Anencephaly in calves at least those we observed and defined in this study is localized defect confined to the brain, eye and skull. No spinal defect was observed in the calves.     

Lysozyme in calves

Relatively high lysozyme concentrations, depending on age, were recorded from intestinal content, spleen, liver, kidney, lung, lymph nodes, and mucosa of calves. Yet, only minor quantities of lysozyme were found in blood serum or plasma and in granulocytes. Physicochemical characterisation, precipitation, using polyclonal antisera, and crosswise neutralisation of lysis reaction were likely to suggest occurrence of immunological relationship reactions as well as differences between organ lysozymes, on the one hand, and intestinal lysozymes, on the other.     

Salmonellosis in calves

Despite the efforts of both physicians and veterinarians, the number of cases of salmonellosis per year has held steady or risen. The ability of the organism to live in many different animal species and under inhospitable environmental conditions is likely responsible for Salmonella's prevalence today. Diverse clinical signs occur in salmonellosis; they range from unthriftiness to explosive, necrotizing diarrheas with high mortality. Secondary complications of pneumonia, bone and joint infections, and meningoencephalitis can result from calfhood infections. Treatment of enteric salmonellosis is chiefly aimed at maintaining fluid, acid-base, and electrolyte balance. Bacteremic or septicemic calves also require systemic antibiotics. The control measures for salmonellosis are based on sanitation and management. Individual calf hutches or pens provide adequate isolation if sufficient spacing and good sanitation are maintained. The Salmonella vaccines presently available provide limited protection; however, live vaccines made from auxotrophic strains of Salmonella appear to be more efficacious.     

An Equine Intersex with Unilateral Gonadal Agenesis

Cytogenetic and histological studies have been carried out on an intersex horse which was clinically diagnosed as a cryptorchid. The horse had the general conformation of a stallion but the external genitalia included a well developed vulva and a penis. The right testis which was descended was devoid of germ cells and the left “gonad” located in the cavum vaginale contained neither testicular nor ovarian tissue. The male duct system on both sides were relatively well developed despite the absence of a testis on the left side. Chromosome analysis on cultured cells from the descended testis revealed the presence of four chromosomally-distinct cell types with XX, XY, XXY and XO sex complements indicating a quadruple mosaicism. The presence of polymorphonuclear neutrophils exhibiting a drumstick, in the hemopoietic tissues and a sex chromatin body in the nucleated cells of buccal mucosa suggest that mosaicism prevails in other somatic tissues of the horse. On the basis of information derived from similar conditions in humans and some domestic animals it would appear that this horse resulted from an XXY zygote. The four cell types noted in the horse probably resulted through mitotic mechanisms favouring the loss of an X and a Y at different stages during embryonic development. The absence of gonad on the left side of this horse might be causally related to the preponderance of XO cell types in the somatic blastema during early gonadal differentiation.     

Pharmacokinetics of ricobendazole in calves

The pharmacokinetics of ricobendazole (RBZ) and its major metabolite albendazole sulphone (ABZSO2) were studied in six calves, after administration of RBZ (7.5 mg/kg), using a 10% experimental solution by the intravenous (i.v.) route, a 10% commercial solution by the subcutaneous (s.c.) route, and a 10% experimental suspension by the intraruminal (i.r.) route. Blood samples were drawn during a 60-h period. Plasma drug and metabolite concentrations were determined by HPLC. The pharmacokinetic evaluation in each case was prepared by weighted least-squares nonlinear regression analysis. Ricobendazole i.v. data were best fitted by a two-compartment model. The best pharmacokinetic exponents and coefficients were estimated, and the pharmacokinetic variables for RBZ and ABZSO2 were calculated from them. Similar patterns of plasma disposition were found for RBZ after i.r. and s.c. administration, suggesting delayed release from the s.c. site resembling the slow release of the drug from the rumen.