Study Guide: Chapter 27, Lecture 20

Distinguish between sperm and semen.

Semen contains glandular secretions and sperm. It is the fluid ejaculated from the penis during orgasm. Sperm is the motile microscopic male reproductive cell which is transmitted into the female reproductive system through a process of sexual intercourse.

What are the steps in spermatogenesis? How long does it take?

Sperm develops in the seminiferous tubule. These multiply by mitosis. Differentiate into primary spermatocytes. Meiosis I then occurs to produce 2 secondary spermatocytes, each with a haploid number. The sperm cell will develop by differentiation of each of these haploid cells and is gradually pushes toward the center of the seminiferous tubule. This takes TEN WEEKS: 72 DAYS.

Where in the testis does spermatogenesis occur?

Spermatogenesis takes place within several structures of the male reproductive system. The initial stages occur within the testes and progress to the epididymis where the developing gametes mature and are stored until ejaculation. The seminiferous tubules of the testes are the starting point for the process, where stem cells adjacent to the inner tubule wall divide in a centripetal direction—beginning at the walls and proceeding into the innermost part, or lumen—to produce immature sperm. Maturation occurs in the epididymis.

Describe the hormonal regulation of males from start to finish. Describe each function for each of the hormones.

The hypothalamus secretes FSH and LH by the anterior pituitary. FSH increases sperm production by the testes, and LH promotes the secretion of androgens, mainly testosterone. Androgens stimulate sperm production. They are also carried in the blood to help maintain homeostasis by negative feedback loop, inhibiting selection of both the releasing hormone and LH. Under this: Millions of sperm every day.

What structures of the male reproductive system contribute to the composition of semen?

In addition to testes and ducts: 1. Seminal Vesicle: Secrete a thick, white fluid that contains fructose, which provides most of the energy that sperm uses to propel. 2. Prostate Gland: Secretes a thin, white fluid that further nourishes the sperm. 3. Bulbourethral Glands: These two glands secrete a clear, alkaline mucus. These glandular secretions and sperm contribute to the composition of semen.

Know the route of the sperm and semen as they travel through the male reproductive system and exit the body.

Leave epididymis during ejaculation From epididymis to the vas deferens. This joins the seminal vesicle. These two ducts combine to unite a ejaculatory duct. This empties in the urethra. It then exits the tip of the penis.

What are the part of mature spermatozoa? What is the function of each part?

Mature sperm made up of three parts: The head which contains the genetic material of the father, the neck or midpiece that contains tons of mitochondria, and the flagella which contain many microtubules needed for cell movement. Also the head contains a thin layer called the acrosome which contains enzymes needed to fertilize.