Histological and immunohistochemical changes of the thyroid gland during the foetal and postnatal period of development in indigenous Large White crossbred pigs

The present study was carried out to ascertain the morphometric, histological and immunohistochemical changes (expression of calcitonin and somatostatin) in the thyroid gland of indigenous local pig crosses during the foetal and postnatal period of development. A total of thirty foetal thyroids (40) grouped into early and late foetal period, fifteeen (15) prepubertal and ten (10) pubertal thyroids obtained from slaughtered pigs in the local abattoir were used. Histomorphometrically, all the measured parameters increased with development in all thyroid age group. The mean values were significantly different at P0.05 among ages. Histologically, significant age-related variations in the structure of the foetal and postnatal thyroids were observed in the follicles, colloid, colloid vacuoles, follicular cells and interfollicular connective tissue. Calcitonin was demonstrated in the foetal and postnatal parafollicular cells, while somatostatin was only localised in the pubertal parafollicular cells. The study provides strong evidence of thyroid functionality during the late foetal period that changes with age during the development.