Δημήτρης Λουτράδης, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Πέτρος Δρακάκης, Αναπληρωτής Καθηγητής, Ιατρικής Σχολής, ΕΚΠΑ
Κωνσταντίνος Καλλιανίδης, Αναπληρωτής Καθηγητής, Ιατρικής Σχολής, ΕΚΠΑ
Embryogenesis is one of the most important procedure in the beginning of life. During this procedure the embryo undergoes significant physiological and morphological alterations, from the first developmental stage until the implantation into the endometrial.
Prenatal development initiates by fertilization, the moment when the sperm penetrates through zona pellucida into the ovum. As a result, the sperm nucleus consolidates with the ovum nucleus, enabling fusion of their genetic material. The union of the genetic cells marks the development of the zygote and the initiation of embryonic cleavage. During the first cleavages, the Embryonic Gene Activation (EGA) is taking place, a procedure by which an embryo transcribes its newly formed genome. The fifth cleavage involves the compaction, when the blastomeres undergo significant morphological and structural changes, maximizing their contact with one another and forming a compact ball of cells. Eventually, the resulting developmental structure, called the blastocyst, hatches from the zona pellucida, in order to achieve implantation in the uterus.
The nonapeptide oxytoxin (OT) is a hypothalamic neuropeptide, which is released into the blood circulation from the neural lobe of the pituitary, inducing uterine contractions during parturition and milk injection during lactation. Additionally, OT is proved to have other roles in reproductive and social behavior in mammals, in mediating maternal behavior, sexual receptivity and partnership bonding and has been proposed as ‘Love hormone” (Young, L.J. et al., 1998). However, it seems to affect many other pathways and yet, these roles remain to be clarified. It is only the last few years that the OT system has been studied in relation with the prenatal development and the establishment of pregnancy.
The purpose of this dissertation is to detect oxytoxin secretion of preimplanted mouse embryos. For this reason, we induced ovarian stimulation of female mice and achieved fertilization in vivo with male mice and afterwards we collected mice embryos and cultured them until the stage of blastocyst. The culturing medium of embryos was collected at each developmental stage, in order to be examined with ELISA technique. According to the data results, different amounts of oxytoxin concentrations in culture mediums have been detected, in each developmental embryo stage. This fact is probably related to the procedure of embryonic gene activation.
The expression of oxytoxin hormone is supposed to be crucial in many pathways of reproduction. Thus, it seems that oxytoxin also participates in early embryogenesis, affecting not only the embryos but also the uterine tissues. The comprehension of this mechanism could provide a useful tool in IVF techniques, targeting at the improvement of the embryo quality, as well as at the successful implantation and the establishment of pregnancy.