Estudo microscópico e macroscópico, com enfoque radiográfico e de alizarina, no desenvolvimento embrionário e fetal de gatos domésticos (Felis catus) em diferentes idades gestacionais

Abstract

The domestic cat was named Felis catus by Carolus Linnaeus in his book Systema Naturae, in 1798. The family Felidae has many morphological similarities with wild felines. The study of the embryology of the domestic cat is of great value considering its importance as an experimental model for the wild cats endangered from extinction, especially in the research related to reproductive biology. The objective of this study is the descriptive embryology of the domestic cat at different stages of pregnancy, through macroscopic description of photographic records, radiographic and alizarin technique, and microscopic description of photographic records by light microscopy. In embryos with an estimated gestational age of 17 days we observed macroscopically an expansion corresponding to the rostral forebrain, the placoid site of lens, cervical flexure, the four pharyngeal arches with grooves dividing the cardiac prominence, a sign of the limb bud, and the presence of somites. In the caudal region of the embryo, we saw the cranio-caudal bend, allowing the same position in format of a "C". In embryos with an estimated age of 22 days, we noticed macroscopically the forebrain, optic vesicle pigmentation of the retina, the optic vesicle, fourth ventricle, liver, fore and hind limbs with a slight distinction between the digits and superficial vascularization. In embryos with an estimated age of 25 days we noticed presence of the forebrain and midbrain, the pronounced cervical curvature of the optic vesicle with strong pigmentation of the retina, the optic vesicle, limbs and chest well developed, distinguishing the digits and pronounced the liver Fetuses with estimated age of 52 days have internal and external structures easily identified in adult animals. With respect to the bone structure we noted that they did not have any radial bone formed, only bone shafts. Microscopically, the embryo of the domestic cat with CR of 0.9cm and estimated age of 19 days revealed the presence of beak, oral cavity with upper and lower nasal cavity, eye and opening of the 4th ventricle of the brain, esophagus, heart with atrium and ventricle, lung, liver, mesonephric ridge, primitive gonad, stomach, forelimb bud, spine and spinal cord in development. This paper is of great importance for study of the internal and external morphology of domestic cats for better understanding of the embryonic development of the species.