- 1. Reproduction www.freelivedoctor.com
2. Reproduction
-
- Not needed for the survival of the individual
-
- Genes from two individual
-
- Increases chances of species survival
www.freelivedoctor.com 3. Sexual Reproduction
- Each individual produces gametes
-
- Formed in gonads by meiosis
- Gametes unite in process of fertilization
www.freelivedoctor.com 4. Sexual Determination
-
- 23 chromosomes from mother
-
- 23 chromosomes from father.
-
- 23 pairs of homologous chromosomes.
-
- 1-22 pairs of chromosomes: autosomal
-
- 23 rdpair are sex chromosomes.
- Chromosomal gender of zygote determined by fertilizing
sperm.
www.freelivedoctor.com 5. Formation of Testes
- First 40 days after conception the gonads of males and females
are similar in appearance.
-
- Spermatogonia and oogonia migrate from yolk sac to developing
embryonic gonads
-
- Gonads could become either.
- TDF (testis-determining factor):
-
- promotes the conversion to testes:
-
-
- gene located on short arm of Y, called SRY (sex determining
region of Y chromosome)
www.freelivedoctor.com 6. Formation of Testes
- Structures in the testes:
-
- Seminiferous tubules:43 to 50 days post conception
-
-
- Nongerminal cells: Sertoli cells (sustentacular cells).
-
- Leydig cells (interstitial cells):
-
-
- Endocrine function: secrete androgens
www.freelivedoctor.com 7. Formation of Testes
- Leydig cells secrete testosterone.
-
- Begins 8 thweek and peaks at 12-14 thweek.
-
- Masculinizes embryonic structures.
- Testosterone then declines to very low levels until
puberty.
-
- Decline occurs by end of second trimester
- Testes descend into scrotum shortly before birth.
-
- Temp about 3 degrees below internal temp
www.freelivedoctor.com 8. Formation of Ovaries
- Absence of Y chromosome and TDF, female develop ovaries.
- Ovarian follicles do not appear until 2 ndtrimester.
www.freelivedoctor.com 9. www.freelivedoctor.com 10. Development
of Accessory Sex Organs and Genitalia
- Presence or absence of testes determines the accessory sex
organs and external genitalia.
- Male accessory organs derived from wolffian ducts.( mesonephric
)
- Sertoli cells secrete MIF(mullerian inhibition factor).
- Female accessory organs derived from mullerian ducts. (
paramesonephritic )
www.freelivedoctor.com 11. www.freelivedoctor.com 12.
Development of Accessory Sex Organs and Genitalia
- Both duct systems in both sexesbetween days 25 and 50
-
- Regression of mullarian ducts begins about day 60
-
- responsible for development of male accessory sex organs
-
- External genitalia identical first 6 weeks, then testosterone
stimulates development of penis
-
- Not the active agent in all cells
-
-
- converted to dihydrotestosterone (DHT) in some target
cells
-
-
- Needed for penis, spongy urethra, scrotum, prostrate
-
- Testosterone directly needed for wolfian derivatives:
-
-
- Epididymis, ductus deferens, ejaculatory duct, SV
www.freelivedoctor.com 13. Development of Accessory Sex Organs
and Genitalia www.freelivedoctor.com 14. www.freelivedoctor.com 15.
Endocrine Regulation of Reproduction
-
- Embryonic testes are active endocrine glands
-
-
- Secrete large amounts of testosterone
-
- Embryonic ovaries not mature until third trimester
-
- Gonads in both sexes relatively inactive
-
- Low levels of sex steroids in both
-
- Due to lack of stimulation
-
- Increased stimulation from gonadotropic hormones
-
- Induce increase in sex steroids
www.freelivedoctor.com 16. Endocrine Regulation of
Reproduction
- Hypothalamus releases LHRH (GnRH) into hypothalamo-hypophyseal
portal vessels.
- Anterior pituitary secretes:
-
-
- In male: interstitial-cell stimulating hormone (ICSH)
-
- FSH: follicle-stimulating hormone.
- Secreted in pulsatile fashion to prevent desensitization and
down regulation of receptors.
www.freelivedoctor.com 17. Endocrine Interactions
- Primary effects of LH and FSH on gonads:
-
- Stimulation of spermatogenesis and oogenesis.
-
- Stimulation of gonadal hormone secretion.
-
- Maintenance of gonadal structure.
www.freelivedoctor.com 18. Endocrine Regulation
-
- Inhibit GnRH from hypothalamus.
-
- Inhibit anterior pituitary response to GnRH.
-
- Inhibin secretioninhibit anterior pituitary release of
FSH.
- Female: estrogen and progesterone.
www.freelivedoctor.com 19. www.freelivedoctor.com 20. Onset of
Puberty
- FSH and LH high in newborn, falls to low levels in few
weeks.
- Puberty: driven by increased secretion of FSH and LH
www.freelivedoctor.com 21. Onset of Puberty
-
- Brain maturation increases GnRH secretion.
-
- Decreased sensitivity of GnRH to negative feedback.
-
- Increased secretion triggers puberty
-
- Late puberty, pulsatile secretion of LH and FSH increase during
sleep.
- Stimulate a rise in sex steroid secretion.
www.freelivedoctor.com 22. Onset of Puberty
- Stimulate rise in testosterone and estradiol-17 .
-
- Produce secondary sexual characteristics.
- Age of onset related to the amount of body fat and physical
activity in the female
- Leptin secretion from adipocytes may be required for
puberty.
www.freelivedoctor.com 23. Pineal Gland
- Secretion influenced by light-dark cycles.
- Inhibit gonadotropin secretion.
- Role in humans not established.
www.freelivedoctor.com 24. 4 Phases of Human Sexual Response
- Excitation phase (arousal):
-
- Myotonia and vasocongestion.
-
- Engorgement of a sexual organ with blood.
-
- Clitoris becomes partially hidden.
-
- Erected nipples become partially hidden by swelling of
areolae.
-
- Uterus and orgasmic platform of vagina contract.
-
- Contractions accompanying ejaculation.
-
- Body return to preexcitation conditions.
-
- Erection possible, but not ejaculation
www.freelivedoctor.com 25. Male Reproduction System
-
-
- Where spermatogenesis occurs.
-
-
- Contain receptor proteins for FSH in Sertoli cells.
-
-
- Contain receptor proteins for LH.
www.freelivedoctor.com 26. Control of LH and FSH Secretion
-
- Testosterone inhibits LH and GnRH production.
-
- Inhibin inhibits FSH secretion.
-
- Aromatization reaction producing estadiol in the brain is
required for the negative feedback effects of testosterone on
LH.
-
- Brain is a target organ for testosterone
www.freelivedoctor.com 27. www.freelivedoctor.com 28.
Testosterone Secretion
- Responsible for initiation and maintenance of body changes in
puberty.
- Stimulate growth of muscles, larynx, and bone growth until
sealing of the epiphyseal discs.
- Promote hemoglobin synthesis.
- Acts in paracrine fashion and is responsible for
spermatogenesis.
www.freelivedoctor.com 29. Testosterone Secretion
- Negative feedback of testosterone and inhibin
-
- Keep relatively constant levels of gonadotropins
-
- Results in relatively constant levels
-
-
- At menopause: no more sex steroids
-
- In males, gradual decrease
www.freelivedoctor.com 30. Endocrine function: testes
- Testosterone: main androgen
- Sertoli and Leydig cells secrete small amounts of
estradiol.
-
- Have receptors for estradiol (as do other male structures)
-
- May be needed for spermatogenesis
- Estradiol may be responsible for:
-
- Negative feedback in brain.
-
- Sealing of epiphyseal plates.
-
- Regulatory function in fertility.
www.freelivedoctor.com 31. Spermatogenesis
-
- Replicate initially by mitosis.
- One becomes a primary spermatocytes undergoesmeiosis:
-
- 2 ndmeiotic division produce 4 spermatids.
www.freelivedoctor.com 32. Spermiogenesis
- Maturation of spermatozoa.
- Cytoplasm is pinched off and ingested by the Sertoli cell
cytoplasm.
www.freelivedoctor.com 33. Sertoli Cells
-
- Prevents autoimmune destruction of sperm.
-
- Produce FAS ligand which binds to the FAS receptor on surface
to T lymphocytes, triggering apoptosis.
- Phagocytize residual bodies:
-
- Transmit information molecules from germ cells to Sertoli
cells.
- Secrete ABP (androgen-binding protein):
-
- Binds to testosterone and concentrates testosterone in the
tubules.
www.freelivedoctor.com 34. Hormonal Control of
Spermatogenesis
- Testosterone required for completion of meiosis and spermatid
maturation.
- Testes secrete paracrine regulators:
- FSH necessary in the later stages of spermatid maturation.
www.freelivedoctor.com 35. Male Accessory Organs
-
- Resistance to pH changes and temperature.
- Seminal vesicles secrete:
www.freelivedoctor.com 36. Erection, Emission, and
Ejaculation
-
- Increased vasodilation of arterioles.
-
- Blood flow into the erectile tissues of the penis.
-
- Movement of semen into the urethra.
-
- Forcible expulsion of semen from the urethra out of the
penis.
www.freelivedoctor.com 37. Female Reproductive System
-
- Contain large number of follicles which enclose ova.
-
- Extensions called fimbriae partially cover each ovary.
-
- At ovulation, secondary oocyte is extruded.
www.freelivedoctor.com 38. Female Reproductive System
- Fallopian (uterine) tubes:
-
- Ova drawn into the tube by cilia.
-
- Endometrium shed during menstruation.
www.freelivedoctor.com 39. Ovarian Cycle
- 5 mo. gestationovaries contain 6-7 million oogonia.
- Oogenesis arrested in prophase of 1 stmeiotic division (primary
oocyte).
-
- 2 million primary oocytes at birth.
-
- 400,000 primary oocytes at puberty.
- 400 oocytes ovulated during the reproductive years.
www.freelivedoctor.com 40. Ovarian Cycle
- Primary oocytes contained in primary follicles.
-
- FSH stimulates cell growth.
- Develop into secondary follicles.
- Fusion of its vesicles into the antrum.
- Mature graafian follicle:
- 1 stmeiotic division completed (secondary oocyte).
www.freelivedoctor.com 41. www.freelivedoctor.com 42. Ovarian
Cycle
-
- Theca cells secrete testosterone. Granulosa cells: contain the
enzyme aromatase to convert testosterone into estrogen.
www.freelivedoctor.com 43. Ovulation
- Graafian follicle forms bulge on surface of ovary.
- Extrudes secondary oocyte into the uterine tube.
- Empty follicle becomes corpus luteum and secretes:
-
- If not fertilized becomes corpus albicans.
www.freelivedoctor.com 44. Menstrual Cycle
- Duration approximately 28 days.
- Day 1 is the first day of menstruation.
www.freelivedoctor.com 45. Follicular Phase
- Stimulates production of FSH receptors on granulosa cells.
-
- Follicles grow and become secondary follicle.
- Granulosa cells secrete estradiol.
- Increases sensitivity of FSH receptors.
- FSH and estradiol stimulate production of LH receptors in
graafian follicle.
www.freelivedoctor.com 46. Follicular Phase
-
- Negative feedback on LH and FSH.
- Hypothalamus increase frequency of GnRH pulses.
- Augments the ability of anterior pituitary to respond to GnRH
to increase LH secretion.
www.freelivedoctor.com 47. Follicular Phase
-
- LH surge begins 24 hours before ovulation.
- FSH increase stimulates development of new follicles.
www.freelivedoctor.com 48. Ovulation
- Under FSH, graafian follicle grows large and thin-walled.
- Wall of graafian follicle ruptures.
- Ist meiotic division is completed.
www.freelivedoctor.com 49. Luteal Phase
- LH stimulates formation of the empty follicle into corpus
luteum.
-
- Plasma concentration rapidly rises.
- Negative feedback on LH and FSH.
www.freelivedoctor.com 50. Luteal Phase
- Corpus luteum regresses unless fertilization occurs:
- Withdrawal of estradiol and progesterone cause menstruation to
occur.
www.freelivedoctor.com 51. www.freelivedoctor.com 52.
www.freelivedoctor.com 53. Endometrial Changes
- 3 phases of endometrium changes:
www.freelivedoctor.com 54. Proliferative Phase
- Ovary is in follicular phase.
- Estradiol stimulate growth of endometrium.
- Stimulate production of receptor proteins for
progesterone.
- Cornification of vaginal epithelium occurs.
www.freelivedoctor.com 55. Secretory Phase
- Ovary is in luteal phase.
- Progesterone stimulates development of uterine glands, which
become engorged with glycogen.
- Endometrium becomes thick, vascular and spongy.
- Cervical mucus thickens and becomes sticky.
www.freelivedoctor.com 56. Menstrual Phase
- Progesterone cause constriction of spiral arteries.
- Necrosis and sloughing of endometrium occurs.
www.freelivedoctor.com 57. www.freelivedoctor.com 58.
Menopause
- Cessation of ovarian activity.
- Ovaries depleted of follicles.
- Estradiol and inhibin withdrawl causes hot flashes, and atrophy
of the vaginal wall.
www.freelivedoctor.com 59. Fertilization
- Ejaculation 300 million sperm, 100 reach (uterine) fallopian
tube.
- Fertilization occurs in the uterine tubes
-
- Acrosome of sperm contains hyaluronidase, an enzyme that
digests a channel through zona pellucida.
- Sperm fuses with ovum cell membrane.
www.freelivedoctor.com 60. Fertilization
- As fertilization occurs, secondary oocyte completes 2 ndmeiotic
division.
- Sperm enters ovum cytoplasm.
- Ovum nuclear membrane disappears, zygote formed.
www.freelivedoctor.com 61. Blastocyct Formation
-
- 30-36 hrs. after fertilization the zygote divides by
mitosis.
-
- Surrounding chorion: trophoblasts form placenta.
www.freelivedoctor.com 62. Implantation
- 6 thday after fertilization, blastocyst attaches to uterine
wall.
- Blastocyst secretes enzymes that allow blastocyst to burrow
into endometrium.
- Trophoblast cells secrete hCG.
www.freelivedoctor.com 63. hCG
- Human chorionic gonadotropin.
- Trophoblast cells secrete hCG.
- Signals corpus luteum not to degenerate until placenta secretes
adequate [hormone].
www.freelivedoctor.com 64. Placenta
- Syncytiotrophoblast secretes enzymes that create blood filled
cavities in the maternal tissue.
- Cytotrophoblast then from projections (villi) that grow into
the venous blood.
-
- Producing chorion frondosum on the side that faces the uterine
wall.
- Other side of chorion bulges into the uterine cavity.
www.freelivedoctor.com 65. Placental Changes
-
- Accumulation of glycogen.
- Decidua basalis: maternal tissue in contact with the chorion
frondosum.
- Maternal and fetal blood do not mix.
www.freelivedoctor.com 66. Amnion
- Amnionic fluid contains sloughed cells of the fetus.
www.freelivedoctor.com 67. Placenta Function
- Synthesis of proteins and enzymes.
www.freelivedoctor.com 68. Placental Hormones
- Chorionic somatomammotropin.
www.freelivedoctor.com 69. Placental Hormones
-
- Placenta must cooperate with the adrenal cortex in the fetus to
produce estrogen.
-
- Inhibit prolactin secretion.
-
- Enlargement of mothers uterus.
www.freelivedoctor.com 70. Placental Hormones
-
- Suppresses uterine contractions.
-
- Stimulates uterine growth .
-
- Stimulate development of alveolar tissue of the mammary
gland.
www.freelivedoctor.com 71. Parturition
- Estrogen in late pregnancy:
-
- Increases amount of oxytocin stored.
-
- Stimulate production of oxytocin receptors in myometrium.
-
- Stimulate prostaglandin production.
www.freelivedoctor.com 72. Lactation
- Hypothalamus releases PRH.
- Anterior pituitary releases prolactin:
-
- Stimulate milk production.
- Oxytocin needed for milk letdown.
www.freelivedoctor.com 73. www.freelivedoctor.com 74.
www.freelivedoctor.com