Male Reproductive System

Biology 2122

Introduction1. Primary sex organ (gonads) are the testes

2. Testes produce sperm via ‘spermatogenesis’– Meiosis

3. Sex hormones (androgens) – play vital roles in development and function of reproductive

organs and sexual behavior – Testosterone

Reproductive Organs (sagittal view)

Scrotum and Testes 1. Scrotum – Function– Structure

• Dartos and Cremaster muscles

2. Testes – Function – Structure

• Tuica vaginalis and albuginea• Semineferous tubules • Rete testes• Epididymis • Ductus Deferens

Penis and Duct System 1. Penis Structure

– Perineum; Glans Penis – Prepuce – Corpus spongiosum– Corpora cavernosa

• Crura

2. Epididymis – P.S. epithelium – 20 days – sperm

3. Ductus Deferens – Ampulla – Ejaculatory duct – P.S. Epithelium

4. Urethra– Prostatic; membranous; spongy

Seminiferous Tubules 1. Function– Produce Sperm

• Spermatogenesis

2. Structure – Spermatogonia – Interstitial Cells

3. Spermatogenesis – Meiosis – Spermatocytes to Spermatids– Sperm – Sustentacular Cells

• Sertoli cells

Meiosis and Mitosis

Mitosis and Meiosis

Spermatogenesis - Animation

Development of Sperm

Head

Midpiece

Flagella

Prostate and Semen 1. Prostate– Secretion – Function

2. Semen – Contents

• pH

– Function– Prostaglandins – Relaxins – Amount

Horomonal Regulation • (1). Hypothalamus, anterior pituitary and testes (brain-

testicular axis)

• (2). Four events that occur– (1). Release of GnRH– (2). GnRH stimulate release of FSH and LH– (3). FSH and spermotogenesis

• Stimulates sertoli cells to release ABP

– (4). LH binding to interstitial cells • Interstitial cell-stimulating hormone

Hormonal Regulation1. GnRH released

2. GnRH to pituitary cells

3. FSH and ABP

4. LH binding to interstitial cells

5. Testosterone levels rise

6. Testosterone enters the blood stream

7. Testosterone ‘feedback’

8. Inhibin

Secondary Sex Characteristics • (1). Induced in nonreproductive organs

(testosterone)

• (2). Characteristics– Pubic, facial and axillary hairs– Larynx enlarges– Skin thickens, oily– Skeletal muscles (density; size and mass)– BMR increased (increases sex drive)