Male Reproductive System Quiz

Spermatogenesis

• Type B spermatogonium is pushed inward and becomes a primary spermatocyte.
• Primary spermatocyte undergoes meiosis, which consists of two successive cell divisions that reduce the number of chromosomes in the daughter cells in half.
• During meiosis I, chromosomes replicate and align as homologous pairs, and then separate into different secondary spermatocytes, each receiving only 23 replicated chromosomes.
• In meiosis II, chromatids separate into different daughter cells, resulting in four spermatids with 23 chromosomes each.
• Each spermatid loses its cytoplasm and forms a flagellum, eventually forming a sperm containing 23 chromosomes.

Genetic Diversity of Sperm

• Genetic diversity of sperm is created by two mechanisms: random alignment of paired homologous chromosomes during meiosis I, and crossover during meiosis I, which involves the exchange of DNA between paired homologous chromosomes.

Sperm Anatomy

• A sperm consists of three parts: head, acrosome, and flagellum.
• The head contains a compact nucleus with 23 chromosomes.
• The acrosome covers the nucleus and contains enzymes that help the sperm penetrate a secondary oocyte.

Male Reproductive System

• The primary functions of the male reproductive system are the production of male sex hormones, formation of sperm, and placement of sperm in the female reproductive tract.
• The organs of the male reproductive system include paired testes, accessory ducts, accessory glands, and external genitalia.

Testes

• The testes are male gonads or sex glands that produce sperm.
• Septa divide the testis into lobules, each containing several seminiferous tubules.
• Spermatogenic cells in the seminiferous tubules divide to produce sperm, while supporting cells support and nourish spermatogenic cells and regulate sperm production.
• Interstitial cells fill the spaces between seminiferous tubules and produce testosterone, the primary male sex hormone.

Spermatogenesis Process

• Spermatogenesis is the process that produces sperm by the division of spermatogenic cells.
• It begins at puberty and continues for a lifetime, controlled by follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and testosterone.

Male Reproductive Tract

• The male reproductive tract includes the epididymis, ductus deferens, ejaculatory duct, and urethra.
• The epididymis is a comma-shaped, tightly coiled tube along the top and back of the testis, where sperm mature and are stored.
• The ductus deferens extends from the epididymis and merges with the duct from the seminal vesicle, using peristalsis to move sperm.
• The ejaculatory duct enters the prostate and merges with the urethra, contracting to mix seminal vesicle secretions with sperm and push them into the urethra during ejaculation.
• The urethra extends from the urinary bladder through the penis to the external environment, transporting urine and carrying semen during ejaculation.

Testosterone

• Testosterone is the primary male sex hormone produced by interstitial cells in the testes.
• At puberty, testosterone promotes the development of male secondary sex characteristics, including growth of body hair, increased muscular development, development of heavy bones, broad shoulders, and narrow pelvis, and deepening of the voice.
• Testosterone production starts to decline around 40 years of age, resulting in a gradual decline in the functions of reproductive organs and secondary sex characteristics.

Hormonal Control of Reproduction in Males

• The onset of sexual development begins around 11-12 years old, completing around 15-17 years old.
• At puberty, the hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulates the anterior lobe of the pituitary gland to release two hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
• LH promotes growth of interstitial cells of the testes and stimulates production of testosterone, while FSH acts on supporting cells and works with testosterone to stimulate spermatogenesis.