Breast development extension adrenocorticotropic hormone (ACTH)), and thyroid hormones such as thyroxine (and by extension thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH)) also play permissive but less well-understood/poorly-characterized roles in breast development during both puberty and pregnancy, and are required for full functional development. Leptin has also been found to be an important factor in mammary gland development, and has been found to promote mammary epithelial cell proliferation. In contrast to the female-associated sex hormones, estrogen and progesterone, the male-associated sex hormones, the androgens, such as testosterone and dihydrotestosterone (DHT), powerfully suppress the action of estrogen in the breasts. At least one
Sexual frustration For males it could be that they have testicles and no penis; a male might be born without a penis (aphallia) or be born with one and have it removed (penis removal or penectomy). Men can still ejaculate via prostate stimulation in that case. For females they might not have a clitoris which causes sexual pleasure; a female might have had her clitoris forcibly severed (female genital mutilation) or voluntarily removed (female circumcusion) as part of a medical procedure. Involuntary celibacy is a form of sexual frustration. Sexual frustration Sexual frustration in humans is frustration caused by a discrepancy between