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Wildlife and Endocrinology Overview

Key Concepts

  • Negative Feedback Mechanism

    • A physiological process that helps regulate various functions in the body.

    • Involves a response that counteracts the effect of a stimulus, maintaining homeostasis.

  • Inhibin

    • A hormone produced by Sertoli cells of the testes in males and by the ovaries in females.

    • Functions primarily to inhibit the secretion of follicle-stimulating hormone (FSH) from the pituitary gland.

Male Reproductive Physiology

  • Hormonal Regulation

    • The hypothalamus secretes Gonadotropin-releasing hormone (GnRH).

    • GnRH stimulates the pituitary gland to release two key hormones:

    • Follicle-stimulating Hormone (FSH): Promotes spermatogenesis and development of Sertoli cells.

    • Luteinizing Hormone (LH): Stimulates Leydig cells in the testes to produce testosterone.

  • Leydig Cells

    • Located in the testes, responsible for the production of testosterone.

  • Testosterone

    • A primary male sex hormone involved in the development of male reproductive tissues and secondary sexual characteristics.

  • Spermatogonia

    • The male germ cells that undergo mitosis and meiosis to produce sperm cells.

  • Androgen-binding protein

    • A protein produced by Sertoli cells that binds to testosterone, increasing its concentration in the seminiferous tubules and playing a crucial role in spermatogenesis.

Female Reproductive Cycle

  • Phases of the Ovarian Cycle:

    • Follicular Phase:

    • The phase where follicles in the ovaries grow and mature in response to hormones.

    • Luteal Phase:

    • Following ovulation, the corpus luteum (CL) forms, grows, and becomes functionally active.

  • Estrous Cycle Phases:

    • Proestrus:

    • The phase where the follicles are actively growing.

    • Estrus:

    • The period when the female is receptive to mating, influenced by estrogen levels.

    • Metestrus:

    • Occurs post-ovulation when the corpus luteum begins to grow.

    • Diestrus:

    • The phase when the corpus luteum produces progesterone, maintaining the uterine lining for potential pregnancy.

  • Corpus Hemorrhagicum:

    • A temporary structure formed after ovulation, which is a blood clot that eventually becomes the corpus luteum.

  • Progesterone

    • A hormone produced by the corpus luteum that inhibits the effects of estrogen and maintains high levels during pregnancy, thus preventing further ovulation and preparing the endometrium for potential implantation.