1. Male Reproductive System:
Recall:
Female Reproductive System
Produce estrogen and progesterone for sexual characteristics
Produce and release one large oocyte at regular intervals
Sexual intercourse, receive semen
Produce hormones to prepare endometrium for pregnancy each cycle; shed functional layer by menstruation
Protect/nourish embryo/fetus; expel it during childbirth
Produce milk to nourish newborn
Male Reproductive System:
Produce testosterone for sexual characteristics
Produce large numbers of sperm & store them until ejaculation
Produce fluids to add to semen
Sexual intercourse; ejaculate semen high into vagina

2. Organs of the male reproductive system
Midsagittal view
Posterior view

3. Testis: Approximately 4cm x 2 cm x 2 cm Outside body cavity in scrotum
Divided into compartments;
Each compartment contains a long, coiled seminiferous tubule
Seminiferous tubules are site of spermatogenesis

4. Hundreds of millions of sperm produced per day
Entire process takes about sixty days

6. Spermatogenesis is initiated and stimulated by follicle stimulating hormone (FSH) secreted by the pituitary gland. Testosterone, produced within the testicle, must also be present
FSH is the same hormone that stimulates oogenesis in the ovary.
However, secretion of FSH in women rises and falls each cycle, resulting in the production of just one oocyte;
Secretion of FSH and testosterone in men remains relatively steady so spermatogenesis is continuously stimulated and sperm are continuously produced.

7. The pituitary gland also secretes luteinizing hormone (LH) in male.
LH stimulates formation of the corpus luteum and production of progesterone in the ovary.
In the testicle, LH stimulates the production of testosterone by interstitial cells,which are located between the seminiferous tubules

8. Unlike oogenesis, in which the developing oocyte is surrounded and protected by a follicle, sperm are not produced within follicles
However: developing sperm are protected and supported by a special cell called a sustentacular or Sertoli cell.

9. Sperm leaving the testis next enter a long (>6 meters) coiled tube called the epididymis.
Also located in scrotum, behind the testis
Sperm take about 40 days to pass through the epididymis, maturing and becoming fertile.
They are stored here until ejaculation.

10. From the epididymis, sperm are transported through the vas deferens or ductus deferens which passes upward into the abdominal cavity. This is happening constantly, but occurs much more rapidly during ejaculation.

11. As it passes from the scrotum to the abdominal cavity, the vas deferens is accompanied by the artery, veins, and nerves supplying the testis. All of these are surrounded by a thick covering of connective tissue, and the entire structure is called the spermatic cord

12. The spermatic cord passes through a tunnel called the inguinal canal

13. Within the abdomen, the vas deferens on each side curves backward, then downward and forward, along the side of the bladder.
The end of the vas deferens, called its ampulla, is enlarged.

14. Male Accessory Glands:
Seminal Vesicles: Paired, posterior to bladder. Ducts join vas deferens to form ejaculatory duct.
Produce + 60% of semen volume.
Contains nutrients for sperm.
Contains chemicals to decrease viscosity of cervical mucous, and to stimulate peristalsis of cervix

15. Male Accessory Glands:
Prostate: Inferior to bladder, ejaculatory ducts embedded within it.
Surrounds proximal part of urethra as it leaves the bladder
Produces + 30% of semen volume.
Contains chemicals to:
- Neutralize acidity of vagina;
- Increase sperm motility;
- Cause semen to clot, then liquify.

16. Penis: Root: Embedded in perineum; + 50% of total length
Body or shaft: Outside, covered with skin
Glans: Tip, not covered with skin

17. Penis: Three erectile bodies: - Two corpora cavernosa
- One corpus spongiosum
Fill with blood during erection, causing shaft to line up with root of penis
When blood leaves erectile bodies, shaft of penis droops down into normal position

18. Ejaculation:
Physical stimulation of penis sends autonomic nerve signals to lower (lumbar) spinal cord.
Reflexive nerve signals cause:
Contraction of smooth muscle of vas
deferens to move sperm into ejaculatory
ducts and urethra
Contraction of seminal vesicles & prostate
move their secretions into urethra
Then ….

19. Ejaculation:
Physical stimulation of penis sends autonomic nerve signals to lower (lumbar) spinal cord.
Reflexive nerve signals cause:
Contraction of smooth muscle of vas
deferens to move sperm into ejaculatory
ducts and urethra
Contraction of seminal vesicles & prostate
move their secretions into urethra
Reflexive nerve signals cause:
Contraction of skeletal muscles along root of penis to force semen along urethra and out external urethral orifice

20. During ejaculation: a) Sperm from the epididymis and vas deferens b) Fluid from the seminal vesicles c) Fluid from the prostate All enter the urethra as it passes through the prostate
The urethra then passes through the penis to its tip.

21. Semen: Mixture of sperm, seminal vesicle fluid, prostate fluid
Normal ejaculate:
4 – 6 milliliters
million sperm per milliliter
Alkaline to neutralize acidity of vagina
Contains nutrients for sperm, chemicals to decrease viscosity of cervical mucous and to stimulate peristalsis of cervix
Semen clots immediately after ejaculation to hold it in vagina, then liquifies gradually over 5 to 10 minutes to release sperm X