tailieunhanh - Saladin Anatomy and Physiology The Unity of Form and Function Episode 16

Tham khảo tài liệu 'saladin anatomy and physiology the unity of form and function episode 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | I Text Saladin Anatomy Physiology The Unity of Form and Function Third Edition 27. The Male Reproductive System The McGraw-Hill Companies 2003 Chapter 27 The Male Reproductive System 1045 metaphase I anaphase I and telophase I then an interval called interkinesis then a second cell division consisting of prophase II metaphase II anaphase II and telophase II. The ultimate result is four haploid daughter cells. 3. Prophase I also involves crossing-over an exchange of genes between an individual s homologous maternal and paternal chromosomes. As a consequence the chromosomes passed to a child have new genetic combinations not inherited from one s parents. 4. The production of sperm is called spermatogenesis. 5. Spermatogenesis begins with primordial germ cells which arise in the yolk sac migrate to the gonads and become spermatogonia by the time a boy is born. 6. From puberty to death primary spermatogonia divide by mitosis into type A and type B spermatogonia. The latter develop into primary spermatocytes then enter into meiosis and divide into secondary spermatocytes and finally spermatids. 7. In a process called spermiogenesis spermatids shed excess cytoplasm and grow a tail flagellum thus becoming sperm. 8. The sperm consists of a head containing the nucleus and acrosome and a tail composed of a mitochondria-stuffed midpiece a long principal piece and a short endpiece. 9. Semen is a mixture of sperm 10 of the volume and fluids from the prostate 30 and seminal vesicles 60 . It contains fructose fibrinogen clotting enzymes fibrinolysin prostaglandins and spermine table . Male Sexual Response p. 1037 1. The penis is supplied by a pair of internal pudendal arteries. One branch of this artery the dorsal artery travels dorsally under the skin of the penis and the other the deep artery travels through the corpus cavernosum and supplies blood to the lacunae. The dorsal arteries supply most of the blood when the penis is flaccid and the deep arteries during erection.