Fertilization and early embryonic development in the blue fox (Alopex lagopus)

Abstract

A total of 15 blue fox vixens aged 1-6 years were mated, 12 once on the first day of estrus and three a second time 48 hr after the first mating, and were killed 4 hr to 8 days following mating. Ova were collected from the oviducts, evaluated by stereomicroscopy, and studied by transmission (TEM; N = 49, 12 vixens) or scanning (SEM, N = 11, three vixens) electron microscopy. At 0-3 days after ovulation, the ova had not cleaved and were at different stages of meiotic maturation. In about one-half of these ova, representing all stages of meiotic maturation, a decondensing sperm head without nuclear envelope or a small pronucleus with partial nuclear envelope was observed. No clear relationship was found between maternal meiotic stage and the stage of paternal pronucleus formation. Sperm tails were never identified in the ooplasm. Cortical granules were released after sperm penetration at early stages of meiotic maturation. Thus the block against polyspermic penetration was activated during maturation of the oocyte. The first two-cell stage appeared 4 days after ovulation (3 days after mating), the first four-cell stage the following day (day 5), and the first eight-cell stage 6 days after ovulation (5 days after mating). In a single vixen mated late (7 days postovulation) two- to four-cell stages appeared the following day (day 8). This indicates that the time required for the first cleavage division decreases with increasing interval from ovulation to mating.(ABSTRACT TRUNCATED AT 250 WORDS)

Ovulation, fertilization and preimplantation embryonic development in raccoon dogs ( Nyctereutes procyonoides )

“…Our current results demonstrate that, like dogs (Tsutsui, 1989) and foxes (Farstad et al, 1993), raccoon dogs ovulate oocytes at 25-32 h after first acceptance of mounting. The number of ovulated oocytes in the mating group was comparable to that in the non-mated group, suggesting that the mating itself did not stimulate ovulation.…”

“…The fertilization window for ovulated eggs in most mammalian species generally lies12-24 h after ovulation, but this window is considerably longer in the blue fox (1-3days) (Farstad et al, 1993) and dog (4-8 days) (Xie, 1983). Our unpublished data indicates that all ovulated eggs became aged and could not be fertilized if the first mating was performed at day 5 after first acceptance of mating in the raccoon dog.…”

“…To improve understanding of the genetic basis of potential human homologues of inherited disorders and traits in canine species by using CRISPR/CAS9, we must be able to precisely control canine reproduction and enable access to the germ line and embryo. In many mammals, such as dog (Tsutsui, 1989;Renton et al, 1991;Reynaud et al, 2005) and blue fox (Farstad et al, 1993), early embryonic developmental physiology has been systematically studied. However, there are only preliminary reports on early embryonic development in the raccoon dog (Feng et al, 1992).…”

Biotechnologies de l'embryon dans l'espèce canine

“…Certains ont suggéré que la pénétration des spermatozoïdes était possible dans l'ovocyte canin à des stades immatures de méiose (Van der Stricht, 1923 ;Farstad et al 1993). Si on peut obtenir une telle fécondation atypique chez les mammifères in vitro, du fait de l'immaturité des ovocytes prélevés en anoestrus La technique d'ICSI (IntraCytoplasmic Sperm Injection) pourrait apporter une solution à la fois au faible taux de fécon-dation et au fort taux de polyspermie.…”

Current progress on assisted reproduction in dogs and cats: in vitro embryo production

“…The presence of primary oocytes in the oviducts increases the chance of the oocyte meeting spermatozoa before or during maturation and it has been shown in the fox that primary oocyte can be fertilized and a male pronucleus can be formed irrespective of the stage of oocyte maturation [7].…”