Hormone that stimulates the secretion of milk from females:

The hormone that stimulates the secretion of milk from females is prolactin.

Explanation:

1. Prolactin:
Prolactin is a hormone secreted by the anterior pituitary gland, which plays a crucial role in the production and secretion of milk in females. It is also known as lactogenic hormone or luteotropic hormone.

2. Role of Prolactin:
Prolactin acts on the mammary glands in the breasts to stimulate the production of milk. It is responsible for the development and maintenance of the mammary glands during pregnancy and lactation.

3. Estrogen and Progesterone:
Estrogen and progesterone, which are secreted by the ovaries during pregnancy, prepare the mammary glands for milk production. These hormones stimulate the growth and branching of milk ducts within the breasts.

4. Oxytocin:
Although oxytocin is not the hormone that directly stimulates milk secretion, it plays a crucial role in the milk ejection reflex. Oxytocin is secreted by the posterior pituitary gland in response to suckling or nipple stimulation. It causes the contraction of the myoepithelial cells surrounding the alveoli in the mammary glands, leading to the ejection of milk into the ducts.

5. Feedback Mechanism:
The secretion of prolactin is under the control of a negative feedback mechanism involving hypothalamus, anterior pituitary, and the mammary glands. When the levels of prolactin decrease due to milk removal, the hypothalamus releases a hormone called prolactin-inhibiting hormone (PIH), also known as dopamine or prolactin-inhibiting factor (PIF). This inhibits the secretion of prolactin. On the other hand, when the prolactin levels are low, the hypothalamus releases prolactin-releasing hormone (PRH), which stimulates the secretion of prolactin from the anterior pituitary gland.

Conclusion:
In conclusion, the hormone that stimulates the secretion of milk from females is prolactin. It acts on the mammary glands to promote milk production and is under the control of a complex feedback mechanism involving the hypothalamus and anterior pituitary gland.