The pituitary gland by virtue of its tropic hormones controls the secretory activity of other endocrine glands. Which one of the following endocrine glands can function independent of the pituitary gland ?

The anterior pituitary secretes tropic hormones — TSH, ACTH, FSH and LH — that regulate thyroid, adrenal cortex and gonadal function, respectively [1]. The parathyroid glands produce parathyroid hormone (PTH) as their primary secretion. Unlike the thyroid, adrenals and gonads, which are driven by hypothalamic–pituitary stimuli, parathyroid hormone release is governed directly by circulating ionized calcium via chemosensing in the parathyroid cells, providing a rapid humoral homeostatic control independent of pituitary tropic input. While negative feedback loops regulate many endocrine axes [2], parathyroid regulation is primarily calcium-driven rather than pituitary-dependent, so the parathyroid can function independently of the pituitary.

Sources

1. [1] https://www.ncbi.nlm.nih.gov/books/NBK557556/
2. [2] https://www.ncbi.nlm.nih.gov/books/NBK595005/