25th ANNIVERSARY OF CLONING BY SOMATIC-CELL NUCLEAR TRANSFER: Scientific and technological approaches to improve SCNT efficiency in farm animals and pets.

The birth of Dolly through somatic cell nuclear transfer (SCNT) was a major scientific breakthrough of the last century. Yet, while significant progress has been achieved across the technics required to reconstruct and in vitro culture nuclear transfer embryos, SCNT outcomes in terms of offspring production rates are still limited. Here, we provide a snapshot of the practical application of SCNT in farm animals and pets.

Sonoelastography of Normal Canine Common Calcaneal Tendon: Preliminary Results.

Shear wave elastography (SWE) is a feasible and newly developed ultrasonographic technique which is able to assess elasticity of tissues. The aim of this work was to assess the feasibility of SWE on the normal canine common calcaneal tendon (CCT) evaluating the intra-operator repeatability and reproducibility of single measurements and stiffness of different anatomic CCT portions was examined. Tendons were first evaluated with B-mode ultrasound with a linear probe 8.

Impaired placental vasculogenesis compromises the growth of sheep embryos developed in vitro.

To evaluate how assisted reproductive technologies (ART) affect vasculogenesis of the developing conceptus, we analyzed placental and fetal development of in vitro-produced (IVP) sheep embryos. Pregnancies produced by ART carry increased risk of low birth weight, though what causes this risk remains largely unknown. We recently reported that developmental arrest of sheep conceptuses obtained by ART is most pronounced when the cardiovascular system develops (Days 20-30 of development).

Sheep: the first large animal model in nuclear transfer research.

The scope of this article is not to provide an exhaustive review of nuclear transfer research, because many authoritative reviews exist on the biological issues related to somatic and embryonic cell nuclear transfer. We shall instead provide an overview on the work done specifically on sheep and the value of this work on the greater nuclear transfer landscape.

A short exposure to polychlorinated biphenyls deregulates cellular autophagy in mammalian blastocyst in vitro.

Background: Polychlorinated biphenyls (PCBs) are common environmental contaminants that represent an important risk factor of reproductive disorders in chronically exposed human populations. However, it is not known whether a short accidental exposure of embryos to PCBs before implantation might influence their further development and whether the effect might be reversible.

Methods And Results: To this aim, in vitro-matured sheep blastocysts were incubated with 2 or 4 µg/ml Aroclor 1254 (A1254), a mixture of 60 PCB congeners for 48 h after which blastocyst proliferation and ability for outgrowth in vitro were assessed.

Efficient production and cellular characterization of sheep androgenetic embryos.

The production of androgenetic embryos in large animals is a complex procedure. Androgenetic embryos have been produced so far only in cattle and sheep using pronuclear transfer (PT) between zygotes derived from in vitro fertilization (IVF) of previously enucleated oocytes. PT is required due to the poor developmental potential of androgenotes derived from IVF of enucleated oocytes.

Development of sheep androgenetic embryos is boosted following transfer of male pronuclei into androgenetic hemizygotes.

Androgenetic embryos are useful model for investigating the contribution of the paternal genome to embryonic development. Little work has been done with androgenetic embryo production in domestic animals. The aim of this study was the production of diploid androgenetic sheep embryos.

Developmental and functional evidence of nuclear immaturity in prepubertal oocytes.

Background: The nuclear compartment has been proposed as responsible for the developmental arrest of prepubertal mouse oocytes while the studies on prepubertal sheep and cow oocyte model suggested the cytoplasm immaturity accounts for this failure.

Methods: The apparent disagreement on the causes of developmental defects between these two species prompted us to study: (i) follicular and oocyte growth allometry in lambs, (ii) oocyte compartment (nucleus versus cytoplasm) responsible for developmental failure by nucleus exchange between lamb and adult sheep oocytes, (iii) nucleolar features of prepubertal oocytes by ultrastructural observation and (iv) in vivo developmental survey of prepubertally derived embryos.

Results: The oocyte growth inside the follicle is asynchronous during prepuberty.