OB

Fertilization through the second week

• Fertilization-clevage-morula
• blastocyte-trophoblast- implantation

• end of second week through the eight week
• -basic structures of major body organs and exteran features

end of eighth week until birth

• zona pellucida
• Disappears in 5 days.

• 1.when sperm and ovum combine to form diploid
• 2. travels through fallopian tubes to uterus
• 3.divides by mitoses (cleavage) and all cells are identical

1. 3-4 days

In outer third ampulla of the fallopian tube

Ectoderm- forms CNS, special senses, skin, and glands

Mesoderm-forms skeletal, urinary, circulatory, and reproductive organs

Endoderm-forms respiratory system, liver,pancreas, and digestrive system

Mass of 16 cells

Blastocyte- forms the embryo and amnion

trophoblast- forms the placenta and chorion

5 minutes after intercourse

• 3-5 days (sperm)
• 24 hours (ovum)

• 3-4 more days until implants in endometrium
• Now called blastocyst
• Outside layer of blastocys made up of cells called tropho blasts

chorionic villi, imbed into endometrium and form the placenta

7-10 days

Human chorionic gonadotropin- hormone preserves copus lteum and its progesterone production in order to maintain uterine lining, basis for urine and serum pregnancy tests

• causes enlargement of breasts, uterus, external genitalia,
• stimulates myometrial contractillity

• maintains endometrium
• decreases contractillity of the uterus
• provides nourishment for early conceptus

• 1.acts synergistically with progesterone to maintain pregnancy
• 2.causes relaxation of pelvic ligaments and softens cervix to prepare for delivery

• development of:
• Brain
• Spinal cord
• Heart
• Nerual tube forms
• GI tract
• Leg and arm buds appear and grow out of body

• Brain differentiates
• limb buds grow and develop more

• heart now beats at reg rhythm
• Beginning structures of eyes and ears
• some visible cranial nerves
• muscles become innervated

• Lungs begin to form
• fetal circulation is established
• Liver produces RBCs
• Further develpment of brain
• Primitive skeleton forms
• CNS forms
• Brain waves detectable

• Straightening of trunk
• nipples and hair follicles form
• elbows and toes visible
• arems and legs move
• diaphragm formed
• mouth with lips and early tooth buds

• Rotation of intestines
• facial features develop
• Heart development is complete
• Resembles Human being

• sexual differentiation continues
• buds for all 20 temp teeth laid down
• digestive system shows activity
• head comprises nearly half of fetus size
• face and neck well formed
• urogenital tract completes development
• RBC produced in liver
• Urine begins to be produced and excreted
• fetal gender can be determined by 12 weeks
• lims are long thin, digits are well fomred

• Lanugo (fine hair) develops on the head
• fetal skin is almost transparent
• bones become harder
• fetus makes active movements
• sucking motions are made with the mouth
• amniotic fluid is swallowed
• fingernails and toenails present
• weight quadruples
• fetal movement or QUICKENING detected by mother

• rapid brain growth
• Fetal heart tones can be heard with stethoscope

kidneys continue to secret urine into amniotic fluid

vernix caseosa, white greasy film covers fetus

• eyebrows and head hair appear
• brown fat deposited to help maintain temp
• nails present on both fingers and toes
• muscles well developed

Eyebrows and eyelashes well formed

fetus has hand grasp and startle reflex

alveoli forming in lungs

skin is translucent and red

lugns begin to produce surfactant

Fetus reaches 15 inches in length

rapid brain development

eyelids open and close

nervous system controls some functions

fingerprints are set

blood formation shifts from spleen to bone marrow

fingerprints are set

blood formations shifts from spleen to bone marrow

fetus usually assumes head down postion

Rapid increase in amount of body fat

Increased CNS control of body functions

Rhythmic breathing movements occur

Lungs are not fully mature

Fetus stores Iron, calcium and phosphorus

Testes are in scrotum of male fetus

Lanugo begins to disappear

Increase in body fat

Fingernails reach the end of fingertips

Small breast buds are present on both sexes

Mother supplies fetus with antibodies against disease

Fetus isconsidered full term at 38 weeks

Fetus fills uterus

(Too little amniotic fluid) <500mL at term

uteroplacental insufficiency

fetal renal abnormalities

(Excessive amniotic fluid) >2,000mL at term

maternal diabetes

neural tube defects

chromosomal deviations and malformations of CNS and/or Gi tract that prevents normal swallowing of amniotic fluid by the fetus

AVA- Artery Vein Artery

Wharton's jelly- specialized connective tissue surrounds the three vessels preventing compression, which would cut off fetal blood and nutrient supply

Monozyogic- comes from one zygote that separtes, produces identical twins

Dizygotic twins- comes from 2 separate zygotes, the individuals are different and not identical

Thick outside layer of amniotic sac

adjacent to maternal surface of placenta