1. Human Male Reproductive System Human Reproduction and Development  Reproductive glands are called the testes and are located outside the body cavity in a pouch called the scrotum.  A temperature lower than 37°C is required for the development of sperm.

2. Copyright © 2010 Pearson Education, Inc. Figure 27.3b Structure of the testis. Testis Epididymis Spermatic cord (b)

3. Copyright © 2010 Pearson Education, Inc. Figure 27.3a Structure of the testes. Head of epididymis Body of epididymis Tail of epididymis Efferent ductule Rete testis Straight tubule Duct of epididymis Ductus (vas) deferens Lobule Testis Septum Tunica albuginea Tunica vaginalis Cavity of tunica vaginalis Spermatic cord Seminiferous tubule Blood vessels and nerves (a)

4. Sperm Cells = the male gametes, carries 23 chromosomes  Develop in the testes in the seminiferous tubules.

6.  Travel to the epididymis and are stored  Travel through the vas deferens- TRANSPORTS gametes -The two vas deferens join together and enter the urethra

7. Copyright © 2010 Pearson Education, Inc. Figure 27.3a Structure of the testis. Head of epididymis Body of epididymis Tail of epididymis Efferent ductule Rete testis Straight tubule Duct of epididymis Ductus (vas) deferens Lobule Testis Septum Tunica albuginea Tunica vaginalis Cavity of tunica vaginalis Spermatic cord Seminiferous tubule Blood vessels and nerves (a)

9. Vasectomy A physician makes a small incision in the scrotum, then cuts through and ties off the vas deferens Flow of sperm: testes  epididymis  vas deferens  urethra

10. After a Vasecotomy Sperm are still produced but they cannot travel to the body’s exterior

13. Female Reproductive System The ovaries are the female reproductive organ They produce hormones and eggs= female gametes carry 23 chromosomes

14. An egg (oocyte) will be released from the ovary every month

15. Estrogen and progesterone are steroid hormones made by cells in the ovaries.  The anterior pituitary gland also produces LH and FSH.

16. The egg drifts towards the funnel shaped opening of the oviduct- the infundibulum, pushed by the ciliated fingerlike projections called fimbriae -The egg travels through an oviduct (also called fallopian tubes), a tube that connects to the uterus

17. Copyright © 2010 Pearson Education, Inc. Figure 27.12a Internal reproductive organs of a female. Vagina External os Cervical canal Internal os Wall of uterus Perimetrium Myometrium Endometrium Round ligament of uterus Uterine tube Infundibulum Fimbriae Isthmus Ampulla Lumen (cavity) of uterus Suspensory ligament of ovary Uterine (fallopian) tube Ovarian blood vessels Mesosalpinx Mesovarium Broad ligament Mesometrium Ovary Ovarian ligament Body of uterus Ureter Uterine blood vessels Isthmus Uterosacral ligament Lateral cervical (cardinal) ligament Lateral fornix Cervix (a) Fundus of uterus

18. From the oviduct, the egg would enter the uterus- a hollow, thick walled, smooth muscle organ that functions to receive, retain, and nourish a fertilized ovum

20. Copyright © 2010 Pearson Education, Inc. Figure 27.12b Internal reproductive organs of a female. Left ovary Mesovarium Uterine tube Body of uterus Fundus of uterus Broad ligament Cervix (b) Internal vaginal surface (vaginal wall is cut and reflected superiorly) Fimbriae of uterine tube Round ligament of uterus Mesosalpinx

21. The cervix at the lower end of the uterus has a narrow opening into the vagina, which leads to the outside of the female’s body.

23. Fertilization

24. Fertilization occurs in the fallopian tubes (oviduct)  Process of a sperm joining with an egg  Sperm and eggs each are haploid, and each normally has 23 chromosomes.  Fertilization restores the diploid number of 46 chromosomes.

25. During copulation the man expels millions of sperm into the vaginal canal Sperm can be destroyed by vaginal acid, phagocytes, or the mucus that surrounds the cervix The sperm will travel through the cervix, uterus, and to the fallopian tube to an oocyte

27. -The oocyte is viable for 12 to 24 hours -Sperm is viable 24 to 48 hours after ejaculation

28. -For fertilization to occur, sex must occur no more than two days before ovulation -Fertilization: when the sperm’s chromosomes combine with those of an oocyte to form a fertilized egg (zygote)

29. The tip of each sperm cell is a specialized acrosome that contains acrosin-a lysosome that weakens the plasma membrane surrounding the egg.  Eventually the plasma membrane becomes weak enough that one sperm can penetrate the egg.

30.  Immediately following this penetration, the egg (oocyte) forms a barrier to prevent other sperm from entering the now-fertilized egg- called an ovum

31. Early Development  The fertilized egg is called a zygote at the moment that the genetic material combines  Around 30 hours after fertilization, the zygote undergoes its first mitosis and cell division- the beginning of cleavage

32. Cleavage= Mitotic divisions of zygote by mitosis with little or no growth between successive divisions -First cleavage at 36 hours  two daughter cells (blastomeres)

33.  By the third day, the embryo, called a morula,(16 or more cells) leaves the oviduct and enters the uterus.

34. At day 3 or 4, the embryo of ~100 cells (blastocyst) has reached the uterus

37. .  The blastocyst attaches to the endometrium (the lining of the uterus) around the sixth day and is fully implanted by day 10 – day 14

39. Diagrams showing the approximate size of a human conceptus from fertilization to the early fetal stage. fertilization  1 week  3 weeks  5 weeks  8 weeks  12 week fetus

40. Extraembryonic Membranes  Four extraembryonic membranes form.  These membranes are the amnion, the chorion, the yolk sac, and the allantois.

41. Chorion- will form the fetal part of the placenta Allantois- structural site of the umbilical cord Yolk Sac- forms part of the gut and earliest blood cells Amnion- forms a transparent membrane sac that surrounds the embryo and eventually fills with fluid

42. -As an embryo develops, the chorionic villi begin to grow into the uterine wall and form part of the placenta -Nutrients, oxygen, and wastes diffuse across maternal and fetal blood vessels, and are carried to and from the fetus through the umbilical cord. -The placenta contains tissue from both mother and fetus, but blood does not come in actual contact.

43. The Placenta  Provides food, oxygen, and removes wastes  The placenta has two surfaces  A fetal side that forms from the chorion and faces the fetus  A maternal side that forms from uterine tissue

44. Umbilical Cord is filled with vessels

45. Three Trimesters of Development Human development takes around 266 days from fertilization to birth (280 days since last period)  The time span is divided into three trimesters.

46. First Trimester The heart is pumping blood at the fourth week All tissues, organs, and organ systems begin to develop. At the end of eight weeks, the embryo is called a fetus.

47. 4 ½ week embryo

48. By the 12 th week the sex can be determined externally using ultrasound

49. 2 nd trimester Period of growth Genitalia can be seen on a sonogram Yawns, sucks thumb, makes movements Secretions of the sebaceous glands protect the skin with vernix caseosa

50. 13 week fetus

51. Between 21-30 weeks Eyes open Spinal cord becomes myelinated The testes enter the scrotum in males It is possible for the fetus to survive at this time, but there is a high mortality rate if the fetus is born in weeks 21-30

52. 3 rd Trimester The fetus continues to grow at a rapid rate Fat is laid down in the subcutaneous tissues to insulate

54. Problems with Prematurity The lungs are lacking surfactant production and alveoli can collapse, leading to respiratory failure The hypothalmus is immature and unable to control body temperature

55. Affect on Mother Breasts become more vascular and enlarge The uterus grows from the size of a fist to the xiphoid process The abdominal organs push on the thoracic cavity, displace the stomach and esophagus- causing heartburn, and difficulty breathing The center of gravity change may cause lordosis Fluctuating hormones cause nausea

56. Childbirth (parturition) three stages: 1) Dilation- oxytocin causes rhythmic contractions of the uterus that cause the cervix to become fully dilated to allow for the head to fit through. As the cervix dilates, the tissue thins out or effaces At this time, the amnion membrane may rupture and fluid will escape (water breaks)

57. 2) Expulsion-this stage lasts from full dilation until the baby is born The usual head first delivery is called vertex Buttocks first delivery is called breech

58. 3) Placental stage- is the delivery of the placenta after it detaches from the uterine wall

59. Lactation Rising levels of hormone stimulate the pituitary gland to secrete prolactin, which causes the prepared mammary glands to secrete milk The first secretions are called colostrum True milk is produced around day three in response to sucking Continued breast feeding is required for continued milk production

60. Copyright © 2010 Pearson Education, Inc. Figure 27.15 Structure of lactating mammary glands. Skin (cut) Pectoralis major muscle Suspensory ligament Adipose tissue Lobe Areola Nipple Opening of lactiferous duct Lactiferous sinus Lactiferous duct Hypodermis (superficial fascia) Intercostal muscles Lobule containing alveoli (a)(b) First rib