Male and Female Reproductive Hormone Functions

Posted on Mar 30, 2025 in Biology

Reproductive Hormones: Androgens and Estrogens

Males and females produce both androgens (male-associated hormones) and estrogens (female-associated hormones). The primary difference lies in the amount of each hormone produced and the physiological changes they induce. The adrenal cortex produces both types of hormones:

  • In males, the androgens produced by the adrenal cortex are negligible compared to the amount produced by the testes.
  • In females, the adrenal cortex is responsible for producing approximately 50% of the androgens.
  • These adrenal hormones contribute to muscle and skeletal development.
  • The estrogens produced by the adrenal cortex become more significant for females after menopause, when the ovaries cease production.

At puberty, Gonadotropin-Releasing Hormone (GnRH) produced by the hypothalamus stimulates the pituitary gland to release both Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH).

Hormonal Regulation in Males

In males, LH acts on the interstitial cells (Leydig cells) in the testes, stimulating them to produce testosterone. FSH acts on the Sertoli cells, initiating sperm production (spermatogenesis).

Male Hormonal Feedback Loop

  • Once testosterone reaches the appropriate level, it exerts negative feedback on the hypothalamus.
  • This inhibition stops the hypothalamus from stimulating the pituitary, which in turn stops releasing FSH and LH.
  • The Sertoli cells also produce a substance called inhibin, which specifically inhibits FSH release from the pituitary, further regulating sperm production.
  • When testosterone levels begin to drop, the negative feedback is reduced, and the hypothalamus and pituitary are stimulated to increase LH and FSH release, thereby increasing testosterone production. This feedback loop operates continuously to maintain appropriate hormone levels.

Once males reach puberty and become sexually mature, sperm production occurs constantly throughout their lives.

Male Secondary Sexual Characteristics

  • Testosterone, produced significantly at the beginning of puberty, influences the development of secondary sexual characteristics.
  • This includes stimulating the growth and development of the penis and testes and increasing libido (sex drive).
  • It promotes the development of facial and body hair, the growth of the larynx (creating a deeper voice), inhibits fat deposition, and promotes muscle development.

Hormonal Regulation in Females

In females, the onset of puberty begins similarly to males: GnRH from the hypothalamus stimulates the pituitary gland’s release of FSH and LH.

Female Hormonal Cycles and Feedback

  • FSH causes ovarian follicles to grow. These developing follicles release estrogen, which stimulates the development of the endometrium (the lining of the uterus).
  • LH stimulates the development of the corpus luteum (formed from the follicle after ovulation), which also releases estrogen and, importantly, progesterone.
  • As estrogen levels rise during the follicular phase, they initially exert negative feedback, suppressing FSH release by the pituitary.
  • However, as estrogen levels reach a high peak, they switch to positive feedback, stimulating a surge in LH release. This LH surge triggers ovulation (the release of an egg from the dominant follicle).
  • Following ovulation, the corpus luteum is stimulated by LH to release both estrogen and progesterone, which further develop and maintain the endometrium, preparing it for potential pregnancy.
  • As levels of estrogen and progesterone rise during the luteal phase, they exert strong negative feedback on both the hypothalamus and pituitary, inhibiting the release of GnRH, FSH, and LH.
  • If fertilization does not occur, the corpus luteum deteriorates after about 10-14 days. Consequently, estrogen and progesterone levels fall sharply, causing the shedding of the endometrial lining (menstruation).
  • The drop in hormones removes the negative feedback, allowing FSH and LH levels to rise again, initiating a new cycle. This menstrual cycle repeats from puberty until menopause.

Female Secondary Sexual Characteristics

  • At the beginning of puberty, rising levels of estrogen stimulate the development of secondary sexual characteristics in females.
  • These include the development of breasts, the growth of pubic and axillary (underarm) hair, the widening of the hips, and an increase in subcutaneous body fat deposition.

Masking Agents and Steroid Detection

Certain substances can interfere with the detection of performance-enhancing steroids:

  • Bromantane: This agent can make steroids more difficult to detect in doping tests. (Note: Side effects information was listed as ‘Unknown’ in the original text).
  • Probenecid: This substance can temporarily stop the excretion of certain steroids from the body for a few hours, potentially masking their use. Possible side effects include headache, tissue swelling (edema), and nausea.