Amniotic fluid cytology at parturition from Nelore calves conceived by artificial insemination, embryo transfer, or in vitro production

The aim of the present study was to describe the differences in the cytological pattern of amniotic fluid at the moment of parturition, comparing the data from Nelore calves conceived by in vitro production, conventional embryo transfer, or artificial insemination. Sixty Nelore cows were divided in three groups as follows: Group 1, 20 pregnant cows carrying Nelore calves conceived by in vitro production after follicular aspiration; Group 2, 20 pregnant cows carrying Nelore calves conceived by superovulation of embryo donor cows; Group 3, 20 pregnant Nelore cows carrying calves conceived by artificial insemination. Near to the time of parturition, cows were transferred to a maternity paddock, to allow for observation of parturition. During the expulsion phase, the amnion was punctured and 15 ml of fluid were collected in plastic vials and frozen at -18°C for later analysis. After thawing, the samples were centrifuged and submitted to Hematoxilin-Shorr staining; the glass slides were covered with Canadian Balsam and a cover slip for further evaluation. Epidermal maturity was determined based on the percentage of keratinized cells stained with Hematoxilin-Shorr. Basal and parabasal cells were not identified on the slides from analyzed amniotic fluid samples. The small intermediate cells were characterized by either an oval shape or a polygonal form with a large cytoplasm and central nucleus. The large intermediate cells had a central nucleus and a higher nucleus: cytoplasm ratio when compared to the superficial cells, which were the largest cells observed. The superficial cells were keratinized cells with angular edges, with either a pyknotic nucleus or no nucleus. There were no differences (P > 0.05) among groups when epidermal maturity was analyzed with the Hematoxilin-Shorr staining, thus indicating absence of differences in epidermal development among calves produced by IVP, ET, or AI.