Ovarian features in white-tailed deer (Odocoileus virginianus) fawns and does

Abstract

The knowledge about ovarian reserve is essential to determine the reproductive potential and to improve the methods of fertility control for overpopulated species, such as white-tailed deer (Odocoileus virginianus). The goal of this study was to evaluate the effect of age on the female reproductive tract of white-tailed deer, focusing on ovarian features. Genital tracts from 8 prepubertal and 10 pubertal females were used to characterize the preantral follicle population and density, morphology, distribution of follicular classes; stromal cell density; and apoptosis in the ovary. In addition, uterus and ovary weights and dimensions were recorded; and the number and the size of antral follicles and corpus luteum in the ovary were quantified. Overall, fawns had a greater (P < 0.05) preantral follicle population, percentage of normal follicles, and preantral follicle density than does. The mean stromal cell density in ovaries of fawns and does differed among animals but not between age groups. The apoptotic signaling did not differ (P > 0.05) between the ovaries of fawns and does. However, apoptotic ovarian cells negatively (P < 0.001) affected the preantral follicle morphology and density, and conversely, a positive correlation was observed with stromal cell density. As expected, the uteri and ovaries were larger (P < 0.002) and heavier (P < 0.001) in does than in fawns. In conclusion, this study has shown, for the first time, the preantral follicle population and distribution of classes, rate of morphologically normal follicles, and density of preantral follicles and stromal cells in white- tailed deer. Therefore, the findings herein described lead to a better understanding of the white-tailed deer ovarian biology, facilitating the development of new methods of fertility control.

Preantral follicle population and distribution in the horse ovary

“…Ovaries were divided into (A) three portions (lateral, n = 2; intermediary, n = 1), followed by (B) histological processing and sectioning to allow for evaluation of follicle density and population. The whole follicle population was estimated per ovary using a formula, as previously described ( Gougeon & Chainy 1987 , Gastal et al 2017 b ). (C, D, and E) A square grid sheet with columns and rows represented by letters and numbers, respectively, was placed upon the histological slides for microscopic evaluation.…”

“…To determine the preantral follicle population, the oocyte nucleus was measured and used as a marker, as previously described ( Gougeon & Chainy 1987 ). Then, the population was calculated using the formula N t = (N o × S t × t s )/(S o × d o ), where N t = total calculated number of follicles of a class; N o = number of follicles observed in the whole ovary; S t = total number of ovarian sections made; t s = thickness of each ovarian section (µm); S o = total number of sections evaluated; and d o = mean oocyte nucleus diameter of each follicle class ( Gougeon & Chainy 1987 , Gastal et al 2017 b ). Counting and classification of preantral follicles were performed by K A Alves, while follicle spatial distribution and population were calculated by B G Alves.…”

“…This finding is relatively common in nature due to high incidences of follicular heterogeneity and individual variation; thus, this mare was intentionally kept in the data set to model what is naturally observed in several mammalian species (mare: Alves et al 2016 ; woman: Kristensen et al . 2011 ; cow: Silva-Santos et al 2011 ; doe: Brandão et al 2018 ; deer: Gastal et al 2017 b ; mouse: Malki et al 2015 ). However, to account for the outlier status of this mare’s data, transformations or rank-based statistical tests were used.…”

“…2003 , Kristensen et al . 2011 ; cow: Silva-Santos et al 2011 ; ewe: Fransolet et al 2014 ; doe: Brandão et al 2018 ; deer: Gastal et al 2017 b ; mouse: Dath et al 2010 , Malki et al 2015 ). This follicular heterogeneity and variation can be explained by the dynamic ovarian plasticity that has been suggested to occur in women and mares ( Woodruff & Shea 2011 , Alves et al .…”

Rescue of caprine fetal ovaries, vitrification and follicular development after xenotransplantation in two immunodeficient mice models

“…Based on the context described above, researches have been carried out in the animal reproduction area aiming to increase the reproductive potential of animals with high zootechnical value ( Commin et al, 2012 ) or preservation of endangered mammals ( Gastal et al, 2017 ) such as cervids ( Comizzoli and Wildt, 2013 ; Comizzoli, 2015 ). Ovary tissue xenotransplantation is a potential technique for maintaining and developing genetic material, especially when combined with germplasm preservation methods such as vitrification, allowing better planning and preparation by the involved research teams.…”