John J. Hincapié, D.Sc.
Full Professor and Director of the Laboratory of Biotechnology of Animal Reproduction
To optimize the use of reproductive and productive capacity of animals, biotechnologies such as artificial insemination, semen sexing, embryo transfer and cryopreservation, in vitro fertilization (IVF) and nuclear transfer of somatic cells , have played an important role.
During IVF in cattle, three fundamental stages occur: oocyte maturation, mature oocyte fertilization and embryo culture. Oocytes can be obtained from ovaries of slaughterhouse cows or live animals by the Ovum-Pick-Up (OPU) process also called follicular aspiration. The stage of maturation is of vital importance since the following stages depend on it as well as the production of quality embryos.
The quality of the oocytes depends, to a great extent, on the classification and selection once they are aspirated. Not all collected oocytes will be used, since many of them present damages or abnormalities and therefore are not suitable for maturation and will not be competent. Oocytes with homogeneous cytoplasm and with at least three layers of cumulus oophorus cells are required. On the other hand, the culture media for the different stages must guarantee biophysical parameters of excellent quality. These parameters are osmolarity, the pH, the concentration of CO2 and O2, concentration of nutrients, water quality, energy sources and proteins. Due to the large number of components in the media, they have been classified in undefined and defined, in order to study the effect and function of each of the components in the final production of embryos, survival to the processes of cryopreservation , and in the percentage of viable offspring.
In the laboratory of animal reproduction of the Department of Food Science and Production, the students Carlos Armando Fernández and José Orlando Rosa are conducting an investigation with the objective of evaluating the effect of the supplementation of the in vitro maturing medium with two different promoters/ growth molecules. This work began in 2018 achieving excellent results in the production and quality of in vitro embryos, and resulted in the birth of an in vitro calf produced with promoters / growth molecules in the maturation medium.
The results to date have been very satisfactory, providing the basis to continue developing and establishingthe protocols in somatic cell nuclear transfer in cattle (cloning), which has the following advantages: it can transmit 100% of the genetic data, eliminating the cost of crosses, preserve the genetic material of old animals of high genetic value, sick or even dead, restore endangered species, recover genetic material from elite animals that for some situation have been left out of traditional reproduction programs; However, work must still be done on some aspects to improve the efficiency of the process, since it is very low (2-4% success), which means that costs are high.
Glosario de términos:
Criopreservación: técnica en el cual las células o tejidos vivos son congelados a bajas temperaturas, por lo general entre -80 °C y -196 °C (por lo general en nitrógeno líquido), lo cual disminuye las funciones vitales de una célula o un organismo y se logra mantenerlo en condiciones de vida suspendida por mucho tiempo.
Cumulus oophorus: grupo de células que rodean al oocito.
FIV: Fertilización in vitro
Folículo ovárico: corresponde a un pequeño elemento en forma de bolsa o saco en el ovario, dentro del cual se encuentra el líquido folicular y el oocito hasta su maduración y liberación.
Oocito: también llamado ovocito, corresponde al gametocito femenino, y es el precursor inmaduro del óvulo. Por lo tanto, son células germinales que se generan en los ovarios.
OPU: Ovum-Pick-Up (por sus siglas en inglés), en español se denomina aspiración folicular.