Estimation, morphometry and ultrastructure of ovarian preantral follicle population in agouti (Dasyprocta leporina)

Abstract

The aim of this study was to characterize the preantral ovarian follicular population in agoutis (D. leporina) by estimating the number of follicles at each developmental category, and also describe the morphometry and the specific features of the follicle and the oocyte by using light and transmission electron microscopy. The length of each ovary was measured using a caliper rule, longitudinally sectioned into two halves and both were immediately fixed to perform the estimation of follicular population and ultrastructural analysis. The mean (±S.E.M.) population of follicular per pair of ovary was estimated at 4419.8±532.26 and 5397.52±574.91 for right and left ovaries, respectively, but no differences were observed between them. The diameters for follicles, oocyte and nuclei were: 18.62±3.40μm, 12.28±2.37μm and 6.10±0.93μm for primordial, 23.75±5.70μm, 14.22±3.00μm and 6.70±1.24μm for primary and 88.55±17.61μm, 52.85±17.56μm and 22.33±17.61μm for secondary follicles, respectively. The most of the follicles found belonged to the primordial category (86.63%), followed by primary (13.01%) and secondary (0.35%) one. Additionally, polyovular follicles were observed in all the animals and they represented 7.51% of the total follicles counted. The ultrastructural analysis showed that the oocyte presented a central and regular nuclei, displaying a homogenous mass. Among the organelles, the mitochondria were the most abundant and the oocyte Golgi apparatus was rarely observed. In conclusion, this work shows for the first time the characterization of the population of preantral follicles in the ovary of Dasyprocta leporina. Those information will be useful for further development and adaptation of biotechniques such as germplasm cryopreservation and in vitro gametes manipulation.

Comparison of different intracellular cryoprotectants on the solid surface vitrification of red‐rumped agouti (Dasyprocta Leporina Lichtenstein, 1823) ovarian tissue

“…Each PF was examined in each section in which it appeared and matched with the same follicle on adjacent sections to avoid double counting, thus ensuring that each follicle was only counted once, regardless of its size. The morphology of PFs was also evaluated according to the integrity of the oocytes, granulosa cells and basement membrane (Santos et al, ).…”

“…The PFs were also counted and classified as morphologically normal (if they contained an oocyte with a regular shape and uniform cytoplasm, as well as having organized layers of granulosa cells) or degenerated (when the oocyte exhibited a pyknotic nucleus and/or ooplasma shrinkage, and the granulosa cell layers became disorganized, detached from the basement membrane and/or included enlarged cells). To avoid evaluating and counting a follicle more than once, PFs were analysed only in the sections where the oocyte nucleus was observed (Santos et al, ).…”

Reproductive Technologies Used in Female Neo-Tropical Hystricomorphic Rodents

“…The ovaries were pale yellow in colour with tiny translucent areas that were oval in shape and had a smooth surface with no ovarian bursa [ 14 , 20 , 25 , 40 , 41 , 42 ]. The ovary, found within adipose tissue and supported by the mesovarium, was enclosed by the tunica albuginea and consisted of two layers—the cortex, which was the outer layer, and the medulla, which was the inner layer [ 40 , 41 , 42 ].…”

“…The ovaries were found to be covered by simple, cuboidal to squamous epithelium, with the cortex consisting of cellular connective tissue, in which ovarian follicles—at different stages of maturation—and corpora lutea could be found, while the medulla was made up of loose connective tissue that contained blood vessels [ 14 , 40 , 41 , 42 , 46 ]. De Oliveira et al [ 42 ] noted the presence of developing follicles and corpus luteum in regression during the proestrus phase; Graafian follicles were present during estrus; a hemorrhagic corpus was present during metestrus; and a mature corpus luteum was present during diestrus.…”

“…Agoutis ( Dasyprocta spp.) are medium-sized rodents that weigh between 2–3.5 kg [ 13 , 14 , 15 , 16 , 17 ]. Studies defining the age of puberty in females are lacking, however, Guimarães et al [ 18 ] showed that, under the male effect, puberty in D. prymnolopha was attained at nine months.…”