The more evolved the species, the better the success of reproduction. Animal Reproduction General Rule The more evolved the species, the better the success of reproduction.

Gonads by Gametes “meiosis” (sex cells) Ovaries Eggs Testes Sperm Sexual Reproduction Gonads by Gametes “meiosis” (sex cells) Ovaries Eggs Testes Sperm (sex organs)

Meiosis- occurs only in testes and ovaries Meiosis- occurs only in testes and ovaries. Body cells split to create 2 eggs or sperm, each with half the genes of the mom/dad.

Fertilization- union of sperm and egg to create a Zygote(fertilized egg). Human males produce millions of sperm a day. Only 1 is needed to fertilize the female egg.

Human Reproduction ... a most amazing process!

Male Sex Organs Scrotum- cools testis Testis- produce sperm Scrotum- cools testis Vas deferens- sperm tube (testis to penis) Seminal vessicles- produce semen(fluid and glucose)

Male(cont.) Cowper’s gland- produces enzyme which activates sperm Prostate gland- provides alkalinity (pH > 7) Cowper’s gland- produces enzyme which activates sperm Urethra- penis tube

Male (cont.) Millions of sperm empty into the vagina and begin swimming randomly. Time is crucial because many die quickly and the hardiest will live for only 24 hours.

Female Sex Organs Ovaries- produce 1 egg/mo. (menstrual cycle) Fallopian tubes(oviduct) - tubes connecting ovaries to uterus. 3 day trip for egg. Uterus- womb(baby develops here) 2ls35139

Female (cont.) Vagina- birth canal. Sperms begin their journey here. Cervix- opening from vagina to uterus. Dilates from 0 cm. to 10 cm. at labor. Vagina- birth canal. Sperms begin their journey here.

Female Female sexual anatomy is physically less complicated, but physiologically more complicated due to hormones and the menstrual cycle.

Menstrual Cycle Day 28 Day 1 ?? 14 FSH FSH LH+ Estrogen

Fertilization or Not? Day 28 If fertilized, womb is prepared by increase of hormones(progesterone HCG, estrogen,etc.) Day 28 If not, hormones shut off, uterus lining is released (menstruation); new cycle.

Development (Embryology) ... is the process from zygote to embryo(1st 3 months) to fetus(last 6 months) to birth by a form of cell reproduction called mitosis. 38-40 weeks

Mitosis- occurs in all body cells Mitosis- occurs in all body cells. Cells make exact copies of themselves with all the genes.

After fertilization... Cleavage By mitosis, the zygote turns into a hollow ball of cells called a blastula

Differentiation According to the genetic code, the ball of cells begins to form different tissues and organs.

Amniotic Sac Human Embryo 5 weeks Placenta

Many body parts are formed at 8 weeks.

Bones were stained red in this 11 week old embryo.

3 months: Embryo to Fetus

Uterus Placenta Umbilical cord

Embryo to Fetus At three months, the embryo is fully developed(?) and weighs less than an ounce. It is now called a fetus and will mostly grow for the next 6 months.

Helping Organs Placenta- softball size organ which attaches the fetus to the uterus. Transfers materials.

Helping Organs Amniotic sac- fluid sac around the fetus. Protection.

Helping Organs Umbilical cord- connects fetus to placenta. Carries blood.

Labor (avg. 12-24 hrs.) Contractions are started by a hormone. Head is birthed 1st. Mouth and nose are suctioned. Umbilical cord cut. Afterbirth(placenta and cord).

In humans, the real labor of parenting now begins and in most cultures lasts for many years!!