When the confidence interval of $A$ do not overlap with the mean $B$ then the condition is not verified and $I_{A-B}$ does not contain 0. (True mean difference can then not be 0). As an example, $A = 10, s_A = 5, B = 15, s_B = 7, n_A = n_B = 10$ $I_A = [7.763932, 12.23607]$ $I_B = [11.8695, 18.1305]$ $I_A$ and $I_B$ do overlap but no CI overlap the means $A$ or $B$. $I_{A-B} = [-8.847077, -1.152923]$ So the true value of $A-B$ is lesser than 0, $A$ and $B$ are different. If $B = 13$ then
The thyroid gland also produces another hormone called calcitonin, and the parathyroid glands secrete parathyroid hormone. Parathyroid hormone and calcitonin participate in control of calcium and phosphorus homeostasis and have significant effects on bone physiology.he thyroid gland also produces another hormone called calcitonin, and the parathyroid glands secrete parathyroid hormone. Parathyroid hormone and calcitonin participate in control of calcium and phosphorus homeostasis and have significant effects on bone physiology.
In brief, the thyroid gland is derived from the fusion of a medial outpouching from the floor of the primitive pharynx, the precursor of the thyroxine (T4)-producing follicular cells, and bilateral evaginations of the fourth pharyngeal pouch, which gives rise to the parafollicular, or calcitonin (C) secreting cells.