Vitrification of cat ovarian tissue: Does fragment size matters?

The aim of the present study was to investigate whether or not the size of the ovarian fragment influences its resistance to cryostorage. For that purpose, ovaries were collected from 34 queens (various breeds, age 1-5 year) by routine ovariectomy, transported to the laboratory and then sectioned in different sizes (3 mm × 3 mm × 3 mm, 5 mm × 3 mm × 3 mm and 7 mm × 3 mm × 3 mm) and randomly assigned to a control (GC3, GC5 and GC7, respectively) or vitrified (GV3, GV5 and GV7, respectively) groups. Vitrified-warmed fragments were evaluated by histomorphology and immunohistochemistry (for apoptotic rates by using cleaved caspase-3). Histological examination reveals that 72.97% of the follicles in GV3 and 72.58% in GV5 were normal while only 42.86% of the follicles in GV7. The main morphological alteration presented in all groups was a detachment of the epithelial cells. Similarly, immunohistochemistry evaluation using caspase 3 revealed a small proportion of apoptotic cells in GV3 (8.43%) while in GV7 30.43% of the cells expressed cleaved caspase-3. These findings indicate that fragments sectioned in 3 mm × 3 mm × 3 mm (27 mm3 ) seem more adequate for perfusion of the cryoprotectant, causing less damage to the cell after vitrification-warming.

Experimental infection of pregnant queens with two major Brazilian clonal lineages of Toxoplasma gondii.

Toxoplasma gondii isolates from Brazil are biologically and genetically different from European and North America isolates. Recently, four genotypes were considered the common clonal lineages in Brazil and were designated as types BrI, BrII, BrIII, and BrIV. The pathogenicity of two major Brazilian lineages was investigated after oral inoculation of queens in the middle third of their pregnancies with T. gondii cysts. Twelve pregnant queens without T. gondii antibodies were distributed in group A (infected with a type BrI isolate); group 2 (infected with type BrIII isolate), and group 3 (non-infected control). Infection with type BrI isolate caused toxoplasmosis manifestations and abortion from one litter. Toxoplasmosis manifestations besides premature stillbirth of one litter were observed in queens infected with type BrIII isolate. Indirect fluorescence antibody test showed T. gondii antibodies in all eight infected queens at 30 days after inoculation. In two 10-day-old kittens of the same litter (group 1), titers of 16 and 64 were detected. At the same time, titers of 16, 32, and 32 were detected in three kittens from the same litter (group 2). Experimental infection with tissue cysts from a type BrI and type BrIII isolates of T. gondii developed similar reproductive disturbance in primary infected pregnant queens.