<P> The prenatal development of the fetus includes all the tissue and organ development . Within hours of mating , the sperm and egg undergo fertilization in the oviduct and three days later the egg moves into the uterus . The cells begin to specialize by day six , and attach themselves to the uterus lining by day eleven . From fertilization to day 18 , the endoderm , ectoderm and mesoderm have been forming inside the embryo , and are completely formed by day 18 , the same day the placenta forms . The endoderm transforms into the lungs , trachea , thyroid gland , and digestive tract of the fetus . The ectoderm has a greater role in the development of the fetus . It forms into the skin , nervous system , enamel of the teeth , lining of the intestine , mammary and sweat glands , hoofs , and hair . The mesoderm forms the major organ components that help keep the fetus alive . It forms the muscles and connective tissues of the body , blood vessels and cells , the skeleton , kidneys , adrenal glands , heart , and the reproductive organs . By day 20 , most of the major organs are visible , and the last half of gestation focuses greatly on increasing the size of the fetuses . </P>
<P> The prenatal development of the fetus includes all the tissue and organ development . Within hours of mating , the sperm and egg undergo fertilization in the oviduct and three days later the egg moves into the uterus . The cells begin to specialize by day six , and attach themselves to the uterus lining by day eleven . From fertilization to day 18 , the endoderm , ectoderm and mesoderm have been forming inside the embryo , and are completely formed by day 18 , the same day the placenta forms . The endoderm transforms into the lungs , trachea , thyroid gland , and digestive tract of the fetus . The ectoderm has a greater role in the development of the fetus . It forms into the skin , nervous system , enamel of the teeth , lining of the intestine , mammary and sweat glands , hoofs , and hair . The mesoderm forms the major organ components that help keep the fetus alive . It forms the muscles and connective tissues of the body , blood vessels and cells , the skeleton , kidneys , adrenal glands , heart , and the reproductive organs . By day 20 , most of the major organs are visible , and the last half of gestation focuses greatly on increasing the size of the fetuses . </P>
where are fetal pigs found growing in their mother
where are fetal pigs found growing in their mother
the uterus
the uterus