Anatomy - Male Reproductive System

Describe two ways in which the two compartments of the testes interact.

1. ABP produced by Sertoli cells help concentrate testosterone within the tubules; Testosterone is the only hormone required for spermatogenesis 2. FSH and testosterone work together to stimulate Sertoli cell proliferation

What would you see in a cross-section of a seminiferous tubule?

1. Different developmental stages of sperm (spermatogonium on exterior; spermatid on interior) 2. Sertoli cells: Phagocytoses cast off cytoplasm as sperm develops

What are the clinical signs of adenocarcinoma of the prostate?

1. Elevated PSA levels (Prostatic specific antigen) 2. Palpable hard nodules on the prostate 3. Difficulty urinating and reducing urinary flow

Describe the 2 ducts involved in the male reproductive system

1. Epididymis: "Upon testes"; stores sperm & allows them to mature and be nourished; 20 feet long 2. Vas deferens (ductus deferens): 18" long; muscular tube that contracts w/ ejection and moves sperm along; has cilia and SM 3. Ejaculatory duct: penetrates prostate and brings contents of vas deferens & seminal vesicle into prostatic urethra

Describe hormonal regulation of testes

1. FSH acts on seminiferous tubules to produce sperm & Sertoli cells 2. LH acts on Interstitial cells to produce Testosterone

What are the functions of FSH and LH on cells and in spermatogenesis?

1. FSH stimulates Sertoli cells, spermatocytogenesis, and permeation 2. LH stimulates Leydig cells (Testosterone), and meiosis

What are the four phases of spermatogenesis?

1. Golgi phase: Acrosomal granule develops 2. Cap phase: Acrosomal cap expands over acrosomal vesicle 3. Acrosomal phase: Manchette forms and helps spermatid elongate; Ends w/ spermatid oriented w/ acrosome pointing towards base of seminiferous tubule 4. Maturation phase: Loss of cytoplasm and intercellular bridges; Nonmotile sperm are released into lumen of seminiferous tubule; Become mobile when they leave the epididymis

What are the genital ducts?

1. Intratesticular ducts: Tubuli recti, Rete testes 2. Extratesticular ducts: Ductus eferentes, Epididymis, Vas deferens (has 3 layers of SM in walls to contract and propel sperm forward), Ejaculatory duct

What are the primary constituents of the testes?

1. Leydig cells: Interstitial cells that produce testosterone in the presence of LH 2. Seminiferous tubules: produce sperm & Sertoli cells in presence of FSH

What are the constituents of seminiferous tubules?

1. Myoid cells 2. Sertoli cells 3. Germ cells: Spermatogonia, spermatocytes, spermatids

Describe the location, function, and temperature of the male gonads

1. Primary male gonads = testes: functions to form sperm and produce testosterone 2. Location: housed in scrotum (skin pouch) 3. Testes prefer cooler environment at 95.6F 4. If too cold, testes have cremasteric muscle to raise testes closer to body

What are the glands?

1. Prostate gland: 15-30% of scrxns to activate sperm 2. Seminal vesicles: 60%; fructose to nourish sperm 3. Bulbourethral gland: neutralize acid in vagina

What are the functions of the Sertoli cells? (5)

1. Provide support and nutrition to developing sperm cells 2. Release spermatids as sperm 3. Phagocytose degenerating germ cells and residual bodies 4. Secrete: ABP, calmodulin, plasminogen activator, inhibin 5. Forms blood-testis barrier

Describe the glands that contribute to the contents of semen

1. Seminal vesicles: forms 60% of semen; contains fructose in scrxns to nourish sperm 2. Prostate gland: walnut-sized; forms 15-30% of semen; produces acid scrxn that activates sperm 3. Bulbourethral glands: pea-sized; found in urogenital diaphragm; neutralizes acid in urethra

Describe the stages of spermatogenesis.

1. Spermatogonia divide by mitosis to increase the number of germ cells and make primary spermatocytes 2. Meiosis 1 creates secondary spermatocytes 3. Meiosis 2 creates spermatids spermatocytes 4. Spermiogenesis creates spermatozoa from spermatids

What is the function of Sertoli cells?

1. Supply nutrients and maintain hormonal level for developing sperm 2. Form Blood-testis barrier: Physical barrier btwn blood vessels and seminiferous tubules 3. Monitors concentration of androgen & estrogen in development of sperm 4. Phagocytosis of cast of cytoplasm by sperm cells

What are clinical signs of testicular cancer?

1. Swelling in scrotum 2. Elevated hCG and alpha-fetoprotein levels

What changes occur in males at puberty?

1. Testosterone acts on larynx & thyroid cartilage increases in size 2. Prostate gland & seminal vesicles become active w/ scrxns to form semen

Explain how FSH and androgens synergize to stimulate sperm prodxn at puberty. Describe the hormonal requirements for spermatogenesis after puberty.

1. Testosterone initiates spermatogenesis at puberty, but FSH and testosterone work together to stimulate Sertoli cell proliferation. 2. Spermatogenesis only needs testosterone, but it is enhanced by FSH

What is the machette? What phase of spermatogenesis does it develop?

1. manchette: corset of microtubules surrounding tail and associated w/ elongation of the nucleus; Found in mature spermatids 2. Develops during acrosomal phase

Describe the effects of castration on FSH and LH secretion in the male. Explain the experimental evidence suggesting that the testes produce a polypeptide that specifically inhibits FSH secretion.

Castration increases LH/FSH scrxn by eliminating negative feedback from sex hormones produced by testes. Evidence is that injecting testosterone into castrated animals returns LH levels to pre-castration. Another product of seminiferous tubules is inhibit, which suppress FSH scrxn.

Describe the two compartments of the testes wrt (a) structure, (b) function, and (c) response to gonadotropin stimulation.

Seminiferous tubules 1. Structure: Tubule w/ BM & Lumen; has Sertoli cells that extend from BM to lumen; Developing sperm enveloped by Sertoli cells 2. Function: Produce sperm & form Blood-testes barrier 3. Response to LH/FSH: FSH > Sertoli cells > ABP & Inhibin; FSH also acts on seminiferous tubules to induce spermatogenesis Interstitium 1. Structure: Thin web of CT that fills space btwn tubules; Houses Leydig cells 2. Function: Secrete testosterone 3. Response to LH: Leydig cells produce testosterone

Why can spermatogenesis continue throughout life without using up all of the spermatogonia?

Spermatogonia divide by mitosis to produce more germ cells

Describe embryonic development of sperm in testes

Yolk sac —> 1200 stem cells —> migrate to site of testes formation —> start development of sperm in seminiferous tubules