Male Reproductive Structures
Testes – makes and stores sperm via meiosis. The testes are also responsible for produces testosterone,
the male hormone.
Sperm-male sex cells.
Scrotum- Pouch that encloses the testes.
Penis- organ where sperm leaves the body.
Urethra- where urine leaves.
Seminal Vesicle and Prostate Gland- release liquids into the vas deferens when sperm is moving
through it.
Testosterone is responsible for many of the "male" characteristics.
Epididymis – Where the sperm matures until it’s expelled or reabsorbed.
Vas deferens - tube where sperm travels to the outside of the body.
Bulbourethral gland / Cowper’s gland- adds fluid to the semen during ejaculation.
Semen- a mixture of fluids that looks milky white.
Female Reproductive Structures
* 2 important functions- nourishes, produces, and protects the egg cells.
Vagina-birth canal, tube that leads from an opening outside the body.
Uterus- strong, thick, muscular walls that holds and nourishes the growing embryo.
Cervix- opening of the uterus at the top of the vagina, stretches during birth.
Fallopian Tubes- connects the ovary to the uterus. The tubes where the eggs travel down.
Ovaries- produce, store, and releases eggs.
Eggs-female reproductive cells.
Ovum- egg cell.
* Estrogen is the hormone responsible for secondary sex characteristics.
* Progesterone is the hormone responsible for initiating menstruation.
* Testosterone is the hormone that initiates sperm production and male secondary sex
characteristics.
* Fertilization produces a new cell= zygote. 23 chromosomes from mom and 23 from dad= complete
set!
* An egg is usually a few days old before it implants in the uterus. At this point, it has already divided
several times and is called a blastula.
* The period from fertilization to birth = gestation.
If the zygote has the incorrect number of chromosomes, it may never start growing. An extra
chromosome #21 will result in the baby having Down syndrome.
First Trimester
 Up to 3 months
 Zygote divides several
times to form a hollow
ball called a blastocyst.
 Embryo is implanted into
the uterine wall – takes
about 8-9 days.
 Nourishment begins.
 Gastrula forms-> make
up the germ layers->
which develop into
different structures.
 Ectoderm-= outer layer->
forms skin, nerves, and
sense organs.
 Mesoderm=middle layer> forms bones, muscles,
and tissues.
 Endoderm= inner layer->
digestive system and
lungs.
 All three layers
developing in different
ways is called
differentiation.
 After 8 weeks the major
organs have begun to
develop and then it is
called a fetus
Second Trimester
 Month 3 to 6
 Fetus starts to move.
 By the end it has fully
developed eyes.
 Lungs are starting to
develop.
Third Trimester
 6 months- end
 Brain develops rapidly.
 Regular breathing
 Lungs aren’t fully
developed until the 36th
week.