Used to (re)ntroduce high school anatomy and physiology students to the process of meiosis / gametogenesis. More specifically, this presentation focuses on spermatogenesis and the male reproductive system anatomy.

1. Reproductive System
Overview
Meiosis
Spermatogenesis
Hormone signaling in Males

2. Male and female reproductive systems
Function together to produce offspring
Female reproductive system nurtures developing offspring
Gonads (Ovaries / Testes)
Function as endocrine glands; produce hormones
Function as exocrine glands; produce gametes

3. Gametogenesis
Meiotic division of cells; spermatogenesis and oogenesis
One replication of DNA, two sets of PMAT divisions
Results in Haploid cells (one of each type of
chromosome)
Fusion of haploid cells (fertilization) results in diploid
zygote

10. Possible number
of chromosome
combinations
= 2n

11. Structures of Male Reproductive System
11

12. Male Reproductive System
Testes
Primary organs
Develop in the abdominal
pelvic cavity of fetus
Descend into scrotal sac shortly
before or after birth
Produce the male sex cells
(sperm)
Produce the male hormone
testosterone
Scrotum – sac that holds the
testes
Seminiferous tubules
Within testes, site of
spermatogenesis initiation
Filled with spermatogenic cells
that produce sperm cells
Interstitial endocrinocyte cells
produce testosterone

13. Structures of Male Reproductive
System

15. Structures of Male Reproductive System
15

16. Male Reproductive System:
Internal Accessory Ducts
Epididymis - duct
Sits on top of each testis
Receives spermatids from
seminiferous tubules
Spermatids become sperm cells
Vas deferens - duct
Tube connected to epididymis
Carries sperm cells to urethra
Ejaculatory ducts
Within prostate
Formed by union of seminal
vesicle and vas deferens
Urethra
Shared terminal duct of
reproductive and urinary
systems

17. Male Reproductive System:
Internal Accessory Glands
Prostate gland
Surrounds urethra
Produces and secretes a milky, alkaline
fluid into urethra just before ejaculation
Fluid protects sperm in the acidic
environment of the vagina
40% of semen
Seminal vesicle
Secretes
Fluid rich in sugar used for energy
Prostaglandins – stimulate muscular
contractions in female to propel sperm
forward
Bulbourethral (Cowper’s) glands
Produce a alkaline mucus-like fluid
Secreted just before ejaculation
Neutralizes urine acidity
Lubricates end of penis
Semen
Alkaline mixture
Nutrients
Prostaglandins
1.5 to 5.0 ml per ejaculate
Sperm count of 40 to 250 million / ml

18. Male Reproductive System:
External Accessory Organs
Scrotum
Holds testes away from body
3 C below body temperature
Lined with serous membrane that
secrets fluid
Testes move freely
Testes separated from one
another by septum
Penis
Shaft
Erectile tissues surround urethra
Glans penis
Cone-shaped structure on end of
penis
Prepuce
Skin covering glans penis in
uncircumcised males
Functions
Deliver sperm
Urination

19. Spermatogenesis
Spermatogonia (46 chromosomes)
31-19
Mitosis – produces primary spermatocytes
Undergo meiosis  two secondary spermatocytes
Divides – two spermatids = 4 spermatids
Develop flagella to become mature sperm cells
with 23 chromosomes

24. Sperm cells
Head
Nucleus with 23
chromosomes
Acrosome – enzyme-filled
sac
Helps sperm penetrate
ovum
Midpiece
Mitochrondria that
generate cell’s energy
Tail
Flagellum that propels
sperm forward

26. Hormonal signaling in male reproduction