Which of the following is a androgen? 

Testosterone

The correct answer is option 4. Testosterone.

Let us delve into each hormone listed and explain why Testosterone is the androgen.

1. Estrone (E1):

Type: Estrogen (a class of female sex hormones).

Source: Produced by the ovaries, adipose tissue, and adrenal glands.

Function: Estrone is one of the three main estrogens in the human body. It is less potent than estradiol and is involved in the regulation of the menstrual cycle and the development of female secondary sexual characteristics.

2. Vasopressin:

Type: Peptide hormone.

Source: Produced by the hypothalamus and released by the posterior pituitary gland.

Function: Also known as antidiuretic hormone (ADH), vasopressin plays a crucial role in regulating the body’s retention of water by increasing water reabsorption in the kidneys. It also constricts blood vessels, which helps to increase blood pressure. Vasopressin is not involved in sex hormone functions.

3. Estriol (E3):

Type: Estrogen.

Source: Produced mainly by the placenta during pregnancy.

Function: Estriol is the weakest of the three main estrogens and is primarily produced during pregnancy. It supports the development of the fetus and prepares the body for childbirth. Estriol helps to maintain the uterine lining and is involved in various aspects of fetal development.

4. Testosterone:

Type: Androgen (a class of male sex hormones).

Source: Produced mainly in the testes in males and in smaller amounts in the ovaries in females and the adrenal glands in both sexes.

Function: Testosterone is the primary male sex hormone. It is responsible for the development and maintenance of male reproductive tissues such as the testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, the growth of body hair, and the deepening of the voice. It also plays a role in maintaining libido and overall male fertility.

Summary:

Estrone and Estriol: Both are estrogens, which are primarily female sex hormones involved in the regulation of the menstrual cycle, pregnancy, and the development of female secondary sexual characteristics.

Vasopressin: A peptide hormone involved in water balance and blood pressure regulation, not related to sex hormones.

Testosterone: An androgen, which is the primary male sex hormone responsible for male sexual development and secondary sexual characteristics.

Testosterone is the only androgen among the options provided. It is a key hormone in male sexual development and reproductive function, while the other hormones (Estrone, Vasopressin, and Estriol) serve different roles in the body.