Thyroid Gland: Origin: It is endodermal in origin and in the human embryo, it develops from the primitive foregut. Position: It is the largest endocrine gland. It lies on the ventral and lateral sides of the upper part of the trachea in the neck below the larynx. Structure: It is a brownish red, highly vascular, and butterfly-shaped gland. It is single lobed in reptiles and bi-lobed in birds and mammals. The two lobes connected to each other by a thin strip of connective tissue called an isthmus. Each lobe consists of numerous follicles in close association with thin-walled blood capillaries. … Continue reading Thyroid Gland: Important Hormones And Deficiency Disorder