Objective: Evaluate the White-tailed Deer (WTD) in vitro embryo production (IVP) and oocytes vitrified with Trehalose (TH) or Sucrose (SC). Design/methodology/approach: Total vitrified oocytes were placed into two different groups: TH (n=60) and SC (n=61). Samples were selected and analyzed for viability evaluation TH (n=5) and SC (n=5), nuclear status (NS) TH (n=4) and SC (n=5), Germinal Vesicle (GV), Metaphase I, or not evaluable (NE) after warming. In vitro maturation (IVM) was conducted for 36 h in supplemented TCM-199 medium. Immediately afterwards, oocyte NS was evaluated (n=88) [(GV, MI=immature), (MII=mature)]. In vitro fertilization (IVF) was performed in supplemented TALP medium for 24 h using frozen WTD semen (3x106 sperm/mL), NS was classified [Fertilized (F), Not fertilized (NF), or NE]. Results: After warming, viability for the TH group (n=5) was 60% versus 40% for SC group (n=5), however, oocytes in both groups were immature (GV and MI stage). For IVM, NS evaluations of the TH group (n=38) revealed no maturation versus 2% in the SC group (n=50) (MII stage=matured). IVF evaluations for the TH group (n=10) revealed no fertilization compared to 20% in the SC group (n=5). A statistical difference (p>0.05) was not found between the TH and SC groups. Limitations on study/implications: White-tailed Deer in vitro embryo production is not well documented. Findings/conclusions: Future research with a larger number of WTD oocytes is needed for further evaluation of oocyte vitrification IVP techniques as a model for endangered cervids.

Objective: Evaluate the use of Ethylene Glycol (EG), Dimethyl Sulfoxide (DMSO), Sucrose and Fetal Bovine Serum (FBS) as cryoprotectants and their effect on the organization of chromosomes and the arrangement of microtubules, during the vitrification process in goat oocytes matured in vitro and in the development of preimplantation embryos produced in vitro. Design/methodology/approach: In vitro matured oocytes were divided into 3 groups (control group, cryoprotectant exposed group, vitrified group). A mixture of 15% EG, 15% DMSO, 0.4 M sucrose and 20% FBS was used for the vitrification using the Cryotop device. In vitro matured oocytes were warmed and afterwards each group was divided into two more groups. Both groups were subjected to immunofluorescence, the first group to observe the damage produced to the chromosomes and microtubules and the second group to observe the effect on the in vitro embryo development. Results: The combined use of 15% EG, 15% DMSO, 0.4 M Sucrose and 20% FBS during vitrification did not prevent cryoinjuries in goat oocytes and in vitro produced embryos, since embryo development was disrupted before the blastocyst stage by stopping cleavage at the morula stage. This disruption was associated with chromosome decondensation and the absence of a microtubule network, thereby hindering chromosomal segregation. Limitations on study/implications: The effect of conventional cryoprotectants on chromosomes and microtubules arrangement on vitrified goat oocytes and in vitro embryo production. Findings/conclusions: The combined use of 15% EG, 15% DMSO, 0.4 M sucrose and 20% FBS as vitrification cryoprotectants did not prevent cryoinjuries in caprine oocytes and did not improve caprine embryo development in vitro.

Objective: To describe the function of Fec, CA5A and CLSTN2 genes during ovulation in ewes. Design/methodology/approach: A search and analysis of scientific information related to Fec, CA5A and CLSTN2 genes in sheep was performed. Results: Fec, CA5A and CLSTN2 genes are involved at the ovarian level; ewes carrying the first gene were found to have increased ovulation rate, folliculogenesis and granulosa cell differentiation. CA5A stimulates an increased follicular rate and plays an important role in pre-implantation. While CLSTN2 has activity in ovarian development and growth; it also has the ability to interact with other genes involved in follicular maturation, granulosa cell differentiation and development of the ovarian follicle. Limitations on study/implications: Ewes carrying these genes increase the prolificacy rate in the flock. Findings/conclusions: The expression of these genes acts synergistically in the ovulatory process, enhancing the ovulatory response by contributing to endocrine, paracrine and molecular synchronisation, so that the maturation of the oocyte occurs, leading to ovulation.