Sunday, May 9, 2010

Fetal Development

I remain in awe that a body can reproduce its genetic code and create life as seen in this video.

The Making of Mothers

Preheat the oven to 98.6 degrees, place it in the endometrial wall and let it slowly rise over the next nine months. If only fetal development were that simple. Below are some of the highlights of embryologic formation with which most people never really become acquainted. Welcome to life as a medical student.

First Trimester - Weeks 1-14

  • Week 1: Fertilization, morula, blastocyst(Day 5), endometrial implantation(6) and hCG from the syncytiotrophoblast
  • Week 2: A bilaminar disc forms(8) and uteroplacental circulation starts(13)
  • Week 3: The primitive streak is evident and the central nervous system begins via the notochord and neural plate; appearance of somites(20)
  • Week 4: The neural tube closes leaving cranial and caudal neuropores(23), limb buds develop(28), and the heart begins to beat
  • Week 5: Facial development, pharyngeal arches and clefts take shape
  • Week 6: Fingers start to appear(38), endodermal derivative development (lung, stomach, pancreas, intestines, liver, gallbladder, urinary bladder)
  • Week 7: Toes develop, maxillary and medial nasal swellings fuse to form upper lip
  • Week 8: Fetus has the appearance of a baby and begins to move; heart sounds can be heard
  • Week 9: Eyes and ears form as face and other organs continue development
  • Week 10: Male and female genitalia are identifiable
  • Weeks 11-14: Fine hair (lanugo) starts to appear; muscle and bones develop
Second Trimester - Weeks 15-27
The bones begin to harden, finger and toe nails form while the fetal organs continue to develop. Movement can be felt during this period as the fetus kicks, rolls, sucks its thumb and learns to swallow.

Third Trimester - Weeks 28-40
The fetus will double or triple in weight from now until birth. The skin thickens with a layer of fat to maintain body temperature. The senses of hearing, vision, touch and taste are developed and used. Repositioning in the womb is not uncommon in preparation for delivery.

All I can say is that without it, I wouldn't be here. Thanks Mom, Happy Mother's Day.

Board Prep Question of the Week

A male infant has a cleft lip on one side that does not involve the alveolar process or the hard palate. A unilateral cleft lip results from the failure of which two facial prominences to merge?

A. Lateral nasal and maxillary
B. Left and right medial nasal
C. Maxillary and mandibular
D. Medial nasal and maxillary
E. Lateral nasal and Medial nasal 
Answer & Explanation


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