Gross and morphometric anatomical changes of the thyroid gland in the West African Dwarf Goat ( Capra hircus ) during the foetal and post-natal periods of development

The thyroid gland morphology of West African Dwarf goat was investigated in the foetal, pre-pubertal and pubertal age of development in an attempt to evaluate the changes that take place during these periods. It was studied by gross dissection and morphometric determination of size. The results showed that the location of the thyroid gland on the larynx and trachea varied between the cricoid cartilage of larynx and 12 th tracheal cartilage as the age progressed. The right lobe was more cranially located on the larynx and trachea than the left lobe in all age groups. Thyroid isthmus was absent in few foetal thyroid but was consistent in the postnatal thyroids. It became a mere thin fibrous tissue in the older pubertal goats. Accessory thyroid was not observed in all age groups. There were significant differences (p<0.05) in the mean weight, length, width and thickness of thyroids of the studied age groups. All measured gross parameters increased with advancing foetal and postnatal age. The study demonstrated the variability of location, size and presence of isthmus during development of thyroid in WAD goats. Keywords: Thyroid gland, anatomy, morphometry, development, Goats