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Human Reproduction

Human Reproduction. The Male Reproductive System. This consists of: A pair of testes situated in a scrotum The epididymis, vas deferens, ejaculatory duct and urethra The accessory glands: seminal vesicles, prostate glands and Cowper’s glands Penis. The Male Reproductive System. The Testis.

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Human Reproduction

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  1. Human Reproduction

  2. The Male Reproductive System This consists of: A pair of testes situated in a scrotum The epididymis, vas deferens, ejaculatory duct and urethra The accessory glands: seminal vesicles, prostate glands and Cowper’s glands Penis

  3. The Male Reproductive System

  4. The Testis • Testis are the male sex organs, • They occur in a bag like scrotum which lies outside the abdominal cavity • The testes produce sperm, which cannot survive long at body temperature. Sperm leave the body in semen, a fluid produced by the seminal vesicles. • Within each testis are found seminiferous tubules

  5. The Testis These are lined by germinal epithelium cells These cells produce the spermatozoa by spermatogenesis Inside the seminiferous tubules, there are specialised cells called sertoli cells

  6. Sex cells – sperm In males, the sex cells are called sperm. tail middle piece head nucleus containing DNA cell membrane Sperm are produced in sex organs called testes.

  7. The Testis • The growth of hair on the face, armpits and pubic areas • Lowering of voice • Development of muscles which give males their shape such as broad shoulders These cells secrete the male sex hormone called testosterone When sexual maturity (puberty) occurs, testosterone is responsible for the development of male characteristics Such as

  8. What happens during puberty? Humans are born with a complete set of sex organs. However, they do not usually become active until between the ages of 10 and 18. In males, the testes start to make sperm, and in females, the ovaries start to release eggs. This stage of development is calledpuberty. During this important time, many changes take place in the bodies of young men and women.

  9. Ducts responsible for carrying the spermatozoa from the testis to the penis The tubes responsible for carrying the spermatozoa include: • Epididymis • Vas deferens • ejaculatory ducts • urethra

  10. The Testis • These cells are rich in glycogen • This glycogen serves as nutrients for the spermatids as they develop into sperm cells • Between the seminiferous tubules are intestitial cells called cells of Leydig

  11. Tubes Responsible for carrying the spermatozoa The epididymis is a coiled tube lying outside the testis but within the scrotum It leads from seminiferous tubules, stores sperm temporarily Later passes the sperm into vas deferens

  12. Tubes Responsible for carrying the spermatozoa- vas deferens The vas deferens (sperm duct) carries the spermatozoa from the epididymis through the abdomen into the ejaculatory duct

  13. Tubes Responsible for carrying the spermatozoa- ejaculatory ducts The two ejaculatory ducts join the urethra just after it leaves the bladder Contraction of the muscular wall of the ducts forces its content (semen) through the urethra

  14. Tubes Responsible for carrying the spermatozoa - urethra The urethra is a tube which runs through the penis and opens at the tip It is a common tube for the passage of urine or semen

  15. Accessory Glands The tubes transporting the spermatozoa are joined by seminal vesicles: prostate glands and Cowper’s gland

  16. Accessory Glands These glands: Secrete a fluid which promotes movement of the spermatozoa Secretes a fluid which provides nutrition to the spermatozoa

  17. Functions of the accessory glands • Seminal Vesicles • Secretes a fluid that nourishes and enables sperm to move. • Prostate gland • Secretes an alkaline fluid that neutralizes the acidity. • Cowper’s glands • Two glands by prostate that secrete a fluid that neutralizes acidity.

  18. The Penis The penis is the external reproductive organ of the male Made up of spongy tissue Becomes filled with blood causing the penis to become erect Then inserted into the female organ

  19. The male reproductive system

  20. The female reproductive system

  21. An overview This system consists of: A pair of ovaries A fallopian tube or oviduct The uterus or womb The vagina or birth canal The vulva or external opening

  22. The Ovaries The ovaries are the female sex organs Occur un the lower part of the abdominal cavity and are held in place by ligaments Each ovary is made up of a covering of germinal epithelium with a large number of follicles within it

  23. The Ovaries The germinal epithelium produces the follicles Oogenesis takes place within the follicles to produce the ova Follicles secrete the female hormones oestrogen and progesterone

  24. The Ovaries When puberty occurs, the female sex hormones are responsible for the development of female characteristics Such as: Increase in size of breasts Development of pubic and armpit hair And menstruation

  25. The fallopian tubes (oviducts) The fallopian tubes convey ova from the ovaries to the uterus Upper part is expanded into ciliated funnels Partially enclosed ovaries

  26. The Uterus Two fallopian tubes open into the uterus which is pear shaped, hollow organ with muscular walls The ling of the uterus is called endometrium, is richly supplied with blood vessels

  27. The Uterus The neck of the uterus, called the cervix, extends into the vagina The uterus serves for the attachment of the embryo Fertilisation takes place

  28. Gametogenesis

  29. Gametogenesis Spermatogenesis refers to the process by which spermatozoa are produced from the germinal epithelium of the testis Oogenesis is the process where ova is produced from germinal epithelium of the ovaries

  30. Spermatogenesis At puberty, the germinal epithelial cells lining the seminiferous tubules start to produce spermatozoa by meiosis Each germinal epithelium is diploid and in humans the diploid number is 46 Since the sperm is produced by meiosis, each one will be haploid with 22 single chromosome and X or Y chromosome

  31. Spermatogenesis The process is as follows: Cells of germinal epithelium become actively dividing cells called spermatogonia Each spermatogonium, which is diploid (2n), enlarges to become a primary spermatocyte (also 2n)

  32. Spermatogenesis Primary spermatocyte undergoes the first meiotic division forming 2 haploid secondary spermatocytes Each secondary spermatocyte undergoes the second meiotic division to produce 2 spermatids Each spermatid matures to form a spermatozoan Each spermatozoan is made up of a head, a middle-piece and a tail

  33. Hormonal Control of the Menstrual Cycle • Inside the ovary of females there are large sac like structures called Graafian follicles • Each follicle contains a maturing ovum • The growth of he ovum inside the Graafian follicle is controlled by follicle stimulating hormone (FSH) • Secreted by anterior lobe of the hypophysis or pituitary gland • These are produced by the germinal epithelium

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