1. The Reproductive System

2. Male Reproductive System

3. Male Reproductive System
The male gonads (testes) produce sperm and lie within the scrotum
Sperm are delivered to the exterior through a system of ducts: epididymis  ductus deferens  ejaculatory duct urethra
Accessory sex glands:
Empty their secretions into the ducts during ejaculation
Include the seminal vesicles, prostate gland, and bulbourethral glands

4. The Scrotum
Figure 27.2

5. The Scrotum
Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity containing paired testicles.
Spermatic Cord: enclose nerves and blood vessels
The Testes are kept 3C lower than core body temperature (needed for sperm production) controlled by:
Cremaster muscle
When it is cold it contracts pulling the testes up toward the core of the body.
When it is warm these muscles relax allowing the testes to descend away from the body.

6. The Testes

7. Seminiferous Tubules Produce the sperm
Surrounding the seminiferous tubules are interstitial cells that produce Testosterone

8. The Epididymis
Sperm enter the epididymis were excess testicular fluid is absorbed and nutrients are provided to the sperm to enable them become motile
Upon ejaculation the epididymis contracts, expelling sperm into the ductus (VAS) deferens.

9. Spermatids to Sperm Sperm have three major regions
Head – contains DNA and has a helmet like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg
Midpiece – contains mitochondria spiraled around the tail filaments
Tail – a typical flagellum produced by a centriole

10. The Penis

11. Male Sexual Response
Erection: Mediated by parasympathetic nervous system during sexual stimulation. Penile arteries dilate which causes the erectile tissue corpora cavernosa to compress the penile veins draining the penis. Ejaculation: Mediated by the sympathetic nervous system. Muscles of the pelvic floor and accessory glands(seminal vesicles, prostate gland, bulbourethral glands) contract secreting the contents out the urethra as semen.

12. Ductus Deferens and Seminal Vesicles
Ductus Deferens : runs from the epididymis to its an enlarged section (ampulla) where it merges with the seminal vesicle
Sperm and seminal fluid mix in the ejaculatory duct and enter the prostatic urethra during ejaculation
Vasectomy – cutting and ligating the ductus deferens, which is a nearly 100% effective form of birth control
Seminal vesicle lies on the posterior wall of the bladder. They functions to:
and secrete 60% of the volume of semen
Semen – viscous alkaline fluid containing:
fructose: fuel for the road trip
prostaglandins which stimulate reverse peristalsis in the uterus
ascorbic acid

13. Accessory Glands Prostate Gland
Doughnut-shaped gland that encircles part of the urethra inferior to the bladder
Plays a major role in the activation of sperm
accounts for one-third of the semen volume
Its milky, slightly acid fluid, which contains citrate, enzymes, and prostate-specific antigen (PSA),
Acts as a anticoagulant for sperm. Elevated blood levels suggest damage to the prostate which allows PSA to enter the blood. The following are associated with elevated levels:
Prostate cancer, prostatitis and BPH
Bulbourethral Glands (Cowper’s Glands)
Pea-sized glands inferior to the prostate
Produce thick, clear mucus prior to ejaculation that neutralizes traces of acidic urine in the urethra

14. Hormonal Regulation of Testicular Function
The hypothalamus releases gonadotropin-releasing hormone (GnRH)
GnRH stimulates the anterior pituitary to secrete FSH and LH
FSH causes sustentacular cells ( Nurse) to release androgen-binding protein (ABP) and inhibin.
LH stimulates interstitial cells to release testosterone
Testosterone
ABP binding of testosterone enhances spermatogenesis
secondary sex characteristics.

16. Additional Effects of Testosterone
Prostate – converts Testosterone into dihydrotestosterone (DHT) before it can bind within the nucleus.
High levels of DHT may increase prostate size and cause male pattern baldness.
Symptoms of testosterone deficiency:
Increased risk of insulin resistance and DM:
Increased visceral obesity: increases activity of the enzyme aromatase which can convert testosterone into estrogen .
gynecomastia : female breast development in males
Xenoestrogens : compounds found in pesticides, plastic bottles (Bisphenol A) also increase estrogen levels
Decreased muscle mass and bone strength
Sleep apnea
Low Libido

17. Female Reproductive Anatomy
Ovaries are the primary female reproductive organs
Make female gametes (ova)
Secrete female sex hormones (estrogen and progesterone)
Accessory ducts include uterine tubes, uterus, and vagina
Internal genitalia – ovaries and the internal ducts
External genitalia – external sex organs

18. Female Reproductive Anatomy

19. External Genitalia: Vulva
Perineum- space between vagina and anus
Lies external to the vagina and includes the mons pubis, labia, clitoris
Mons pubis – round, fatty area overlying the pubic symphysis
Labia majora – elongated, hair-covered, fatty skin folds covering the labia minora
Labia minora – hair-free skin folds covers the urethral and vaginal openings
Clitoris (erectile tissue)
Primary center for sexual stimulation

20. Vagina Thin-walled tube lying between the bladder and the rectum.
Extending from the cervix to the exterior of the body.
Provides a passageway for birth, menstrual flow, and is the organ for sexual intercourse.

21. Uterus
Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder
Body – major portion of the uterus
Fundus – rounded region superior to the entrance of the uterine tubes
Cervix- distal tip contacts the vagina.

22. Fallopian Tubes
Receive the ovulated oocyte and provide a site for fertilization at the distal quarter of the tube.
Expand distally around the ovary forming the ampulla
The ampulla ends in the funnel-shaped, ciliated infundibulum containing fingerlike projections called fimbriae.

23. Uterine Wall Uterine Wall is composed of three layers
Perimetrium – outermost serous layer; the visceral peritoneum
Myometrium – middle layer; interlacing layers of smooth muscle
Endometrium – mucosal lining of the uterine cavity changes in thickness during the menstrual cycle

24. Ovaries
Paired organs that function as both endocrine and reproductive organs .
Located within the pelvic cavity on either side of the uterus
Each ovary contains primordial follicles consisting of an oocyte and follicular cells.
The ovary is stimulated by pituitary secretions of FSH and LH. These hormones collectively stimulate the growth and maturation of the oocyte within the follicle.
The mature follicle secretes estrogen
Estrogen-induced secondary sex characteristics include:
Increased deposition of subcutaneous fat, especially in the hips and breasts
Widening and lightening of the pelvis
Growth of axillary and pubic hair

25. Ovaries

26. Hormones and Ovarian Development
Follicular phase – period of follicle growth (days 1–14)
Day 1 – GnRH stimulates the release of FSH and LH
FSH stimulates mitosis of the primordial follicle into a primary follicle.
LH stimulates estrogen secretion promoting the growth of the endometrium and development of the fluid filled antrum characteristic in a mature graafian follicle.

27. Luteal phase of the Ovarian Cycle
Luteal phase – period of corpus luteum activity (days 14–28)
(Ovulation ) at Day14 a large surge in LH triggers causes follicle to the rupture ejecting the ovum into the fallopian tube
LH transforms the ruptured follicle into a corpus luteum which produces several hormones:
Inhibin: inhibits further production FSH and LH
progesterone and estrogen which maintain endometrium

28. Luteal phase of the Ovarian Cycle
Human chorionic gonadotropin (hCG) stimulates the continuous secretion of LH preventing the degeneration of the corpus luteum.
If pregnancy does occur, the corpus luteum will continue to produce these hormones until the placenta takes over at about 3 months.
If pregnancy does not occur, the corpus luteum degenerates in 10 days, leaving a white scar (corpus albicans)

29. Endometrium
Has numerous uterine glands that change in length as the endometrial thickness changes
Uterine glands supply fertilized egg with nourishment
glycogen-rich uterine fluid.
Will increase in size during the first half of the menstrual cycle.
Reduction in estrogen levels cause the endometrium to shed

30. Acrosomal Reaction and Sperm Penetration
An ovulated oocyte is encapsulated by:
The corona radiata and zona pellucida
Extracellular matrix
Sperm binds to the zona pellucida and undergoes the acrosomal reaction
Enzymes are released near the oocyte
Hundreds of acrosomes release their enzymes (hyaluronidase) to digest the zona pellucida
Once a sperm makes contact with the oocyte’s membrane:
A calcium mediated reaction blocks other sperm from entering

31. Acrosomal Reaction and Sperm Penetration

32. From Zygote to Blastocyst
Degenerating zona pellucida
Inner cell mass
Blastocyst cavity
Blastocyst cavity
Trophoblast
(a) Zygote (fertilized egg)
(b) 4-cell stage 2 days
(c) Morula 3 days
(d) Early blastocyst 4 days
(e) Implanting blastocyst 6 days
Fertilization (sperm meets egg)
(a)
(b)
(c)
Uterine tube
Ovary
Oocyte (egg)
(d)
Ovulation
(e)
Uterus
Endometrium
Cavity of uterus

33. From Zygote to Blastocyst
Fertilization occurs between the sperm and ovum in the distal ¼ segment of the fallopian tube.
Cleavage – a series of mitotic divisions occur for 3 days after fertilization forming a morula stage (solid ball of cells)
Zona pellucida disintegrates to release a fluid-filled hollow sphere called a Blastocyst
outer cells (trophoblast) helps to form placenta
inner cell mass develops into embryo
Ectoderm – forms structures of the nervous system and skin epidermis.
Endoderm – forms epithelial linings of the digestive, respiratory, and urogenital systems.
Mesoderm – forms muscles and various connective tissues
Implantation of Blastocyst occurs around day 6.

34. The Female Breast
Modified sweat glands consisting of lobes that radiate around and open at the nipple
Areola – pigmented skin surrounding the nipple
Suspensory ligaments attach the breast to underlying muscle fascia
Lobes contain glandular alveoli that produce milk in lactating women
Compound alveolar glands pass milk to lactiferous ducts, which open to the outside
Figure 27.17

35. Lactation
During pregnancy estrogen and progesterone high levels stimulate the hypothalamus to secrete prolactin-releasing hormone (PRH) which targets the anterior pituitary. This results in the secretion of prolactin
Prolactin stimulates the production of milk in the breasts

36. Lactation Suckling stimulates both prolactin and oxytocin :
Prolactin secretion allows for continuous milk production
Oxytocin secretion causes the smooth muscle around the alveolar ducts in the breast to eject the milk for the nipple

37. Chromosomes and Heredity
Heredity = transmission of genetic characteristics from parent to offspring
karyotype = chart of chromosomes at metaphase
The body cells have 23 pairs homologous for a total of 46 chromosomes 2n (diploid number of chromosomes) 22 of the 23 pairs guide genetic expression of most other traits. (autosomes)
Sex cells (gametes) from the ova and the sperm each has 1 chromosome that determine the sex
Sperm and egg contain only 23 chromosomes n ( haploid)
fertilized egg has diploid number of chromosomes

38. Sex Determination of Offspring

39. Karyotype of What Sex ?

40. Questions???