Fortpflanzungsphysiologie und assistierte Reproduktion beim Haushund (Canis familiaris) - eine Literaturstudie Tierärztliche Fakultät - Digitale Hochschulschriften der LMU - Teil 01/07
-
- Education
The aim of this work was the evaluation of literature about physiology of reproduction, assisted reproduction technologies and associated biotechniques in domestic dogs (Canis familiaris).
In the bitch preovulatory follicular luteinization results in exposure of oocytes to increasing concentrations of progesterone 1-2 days prior to ovulation. Ovulation occurs approximately two days after the LH-peak. The bitch ovulates primary oocytes with intact germinal vesicle, which requires 2-5 days for the completion of the meiotic divisions within the oviduct.
Artificial insemination (AI) in bitch can be performed either intravaginally or intrauterinely with fresh, chilled or frozen-thawed spermatozoa. Intrauterine insemination (IUI) may be carried out surgically by laparotomy or laparoscopy or non-surgically using transcervical cathetherization. In the bitch, IUI results in a high whelping rate and litter size comparable to those after natural mating. Cryopreservation of dog semen has been successfully accomplished and a variety of extenders, freezing and thawing protocols have been published. AI with cryopreserved semen generally yields lower pregnancy rates if intravaginal deposition of semen is used.
A reliable method for synchronization and induction of a fertile oestrus cycle as well as superovulation by hormone treatment are not available.
Canine oocytes may resume meiosis spontaneously in vitro, although at a much lower efficiency than in most other domestic species. In vitro maturation (IVM) of oocytes results in 20 to 70 % oocytes entering germinal vesicle breakdown (GVBD). Only 10 to 40 % oocytes progress to metaphase I to II. It has been shown, that cumulus morphology, stage of estrous cycle, oocyte size, cumulus-oocyte communication through gap junctions, age of oocyte donors, and serum supplementation of the culture medium influence the efficiency of IVM. Dog oocytes cultured within advanced preantral and early antral follicles in vitro are competent to resume meiosis and mature to the metaphase stage. The developmental potential of these oocytes was comparable to isolated cumulus oocyte complexes.
The optimal culture conditions required for induction of capacitation and acrosomal exocytosis of canine sperm are yet to be established. Dog spermatozoa are able to penetrate the zona pellucida and the vitellus of homologous oocytes irrespective of the oocyte maturation stage. The developmental potential of fertilized dog oocytes in vitro is very low. Only one case of development to the blastocyst stage after in vitro fertilization (IVF) has been reported.
The surgical transfer of ex vivo collected dog embryos resulted in birth of live puppys although the success rates were low. Up to date no reports of production of live pups after IVF from in vivo or in vitro matured dog oocytes exists. In one study three conceptuses were identified by ultrasonography twenty days after transfer of in vitro fertilised oocytes but no further development could be observed. Reliable protocols for cryopreservation of dog embryos have yet to be developed.
Until recently, there has been limited interest in assisted reproduction techniques in the dogs. The rising significance of dogs as companion animals as well as interest in comparative aspects with wild-life canides will stimulate research in the fields of in vitro production of embryos, cryopreservation and embryo transfer of embryos.
The aim of this work was the evaluation of literature about physiology of reproduction, assisted reproduction technologies and associated biotechniques in domestic dogs (Canis familiaris).
In the bitch preovulatory follicular luteinization results in exposure of oocytes to increasing concentrations of progesterone 1-2 days prior to ovulation. Ovulation occurs approximately two days after the LH-peak. The bitch ovulates primary oocytes with intact germinal vesicle, which requires 2-5 days for the completion of the meiotic divisions within the oviduct.
Artificial insemination (AI) in bitch can be performed either intravaginally or intrauterinely with fresh, chilled or frozen-thawed spermatozoa. Intrauterine insemination (IUI) may be carried out surgically by laparotomy or laparoscopy or non-surgically using transcervical cathetherization. In the bitch, IUI results in a high whelping rate and litter size comparable to those after natural mating. Cryopreservation of dog semen has been successfully accomplished and a variety of extenders, freezing and thawing protocols have been published. AI with cryopreserved semen generally yields lower pregnancy rates if intravaginal deposition of semen is used.
A reliable method for synchronization and induction of a fertile oestrus cycle as well as superovulation by hormone treatment are not available.
Canine oocytes may resume meiosis spontaneously in vitro, although at a much lower efficiency than in most other domestic species. In vitro maturation (IVM) of oocytes results in 20 to 70 % oocytes entering germinal vesicle breakdown (GVBD). Only 10 to 40 % oocytes progress to metaphase I to II. It has been shown, that cumulus morphology, stage of estrous cycle, oocyte size, cumulus-oocyte communication through gap junctions, age of oocyte donors, and serum supplementation of the culture medium influence the efficiency of IVM. Dog oocytes cultured within advanced preantral and early antral follicles in vitro are competent to resume meiosis and mature to the metaphase stage. The developmental potential of these oocytes was comparable to isolated cumulus oocyte complexes.
The optimal culture conditions required for induction of capacitation and acrosomal exocytosis of canine sperm are yet to be established. Dog spermatozoa are able to penetrate the zona pellucida and the vitellus of homologous oocytes irrespective of the oocyte maturation stage. The developmental potential of fertilized dog oocytes in vitro is very low. Only one case of development to the blastocyst stage after in vitro fertilization (IVF) has been reported.
The surgical transfer of ex vivo collected dog embryos resulted in birth of live puppys although the success rates were low. Up to date no reports of production of live pups after IVF from in vivo or in vitro matured dog oocytes exists. In one study three conceptuses were identified by ultrasonography twenty days after transfer of in vitro fertilised oocytes but no further development could be observed. Reliable protocols for cryopreservation of dog embryos have yet to be developed.
Until recently, there has been limited interest in assisted reproduction techniques in the dogs. The rising significance of dogs as companion animals as well as interest in comparative aspects with wild-life canides will stimulate research in the fields of in vitro production of embryos, cryopreservation and embryo transfer of embryos.
Top Podcasts In Education
More by Ludwig-Maximilians-Universität München