An adenohypophysis hormone which is regulated by feedback mechanism is
(a) TSH
(b) Cortisone
(c) Calcitonin
(d) Oxytocin

Options

A. TSH
B. Cortisone
C. Calcitonin
D. Oxytocin.

Answer

To solve the question regarding which adenohypophysis hormone is regulated by a feedback mechanism, we can analyze the options provided:

1. **Understanding the Adenohypophysis**: The adenohypophysis, also known as the anterior pituitary gland, produces several important hormones that are involved in various regulatory mechanisms in the body.

2. **Analyzing the Options**:
- **(a) TSH (Thyroid Stimulating Hormone)**: This hormone is produced by the adenohypophysis and regulates the thyroid gland's production of thyroxine (T4). When thyroxine levels rise, they exert negative feedback on the hypothalamus and the anterior pituitary to reduce TSH secretion. This indicates that TSH is regulated by a feedback mechanism.

- **(b) Cortisone**: Cortisone is not produced by the adenohypophysis; it is a steroid hormone produced by the adrenal cortex. Therefore, it does not fit the criteria of being an adenohypophysis hormone.

- **(c) Calcitonin**: Calcitonin is produced by the thyroid gland, not the adenohypophysis. It helps regulate calcium levels in the body but does not originate from the adenohypophysis.

- **(d) Oxytocin**: Oxytocin is produced by the hypothalamus and stored in the posterior pituitary (neurohypophysis). It does not originate from the adenohypophysis and does not operate under a feedback mechanism like TSH.

3. **Conclusion**: Based on the analysis, the only hormone listed that is produced by the adenohypophysis and regulated by a feedback mechanism is TSH.

Thus, the correct answer is **(a) TSH**.