Development of embryonic and fetal of pacas (Agouti paca, Linnaeus 1766): establishment of experimental model analogous to murine \Germ cells\ linage detection

Author(s)

Andre Luis Rezende Franciolli

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2007-12-18

Examining board members

Maria Angélica Miglino; Carlos Eduardo Ambrosio; Moacir Franco de Oliveira

• Advisor: Maria Angélica Miglino

Abstract

The study aimed elucidates the development of embryonic and fetal of pacas (Agouti paca) and demarcation of the germ sites in embryos at different stages. Seven specimens were used; two embryos and three fetuses from UNESP- Jaboticabal and other two fetuses were from FMVZ-USP collection. The fetuses 1 and 2 showed immaturity facial sharp, eyes covered by a lens and prominent lobes of the ears, the fetuses 3 and 4, showed up with well-developed ears, members thoracic and pelvic in equal level of development, vibrisses around the nasal edges and eye also protected;. The fetus 5 had hairs distributed throughout the body, members thoracic and pelvic with claws, vibrisses on the face, prominent eyes and ears well developed. The embryo 1, presented the optic vesicle with pigmentation of the retina, the fourth encephalic ventricle and cervical curvature and button members in development. The embryo 2, had split the branchial arches and open neuropore cranial; heart and liver were identified, optical vesicle without pigmentation of the retina, the neural tube was opening in the region of the fourth encephalic ventricle, rombencephalon and mesencephalon were in development. Light microscopy, shows the spinal cord, 4 th encephalic ventricle, resence of encephalic vesicles (prosencephalon, mesencephalon and rombencephalon), vertebral column, pituitary gland, oral and nasal cavities, eye, atrium and ventricle heart, lung and diaphragm, as well the metanephron and mesonephron, liver, intestine and mbilical pedicle. The immunohistochemical reactions for OCT-4 were non expressive in organs such as lung, intestine and somites; heart presented a discrete positive reaction, while kidneys and liver obtained an expressive expression, more pronounced in the last one. Vimentina\'s tests showed that all organs stained in different areas, and the reaction whit the actin was negative just in the region of somites. We conclude that the period embryonic/fetal of paca can not be compared with the classical model of rodents; its embryogenesis can be compared with the rats, Guinea pig, rabbits and humans ones. The positive immunolocalization of OCT-4 presents differences according to the gestational age, due to changes embryological tissue. The vimentine as a mesenchyme marker is expressed positively in all organs of the embryo of paca. The actin as immunomarker of smooth muscle was expressive in areas containing muscles. (AU)