Prenatal Development

Week 8 (CRL= 30 mm)

By 8 weeks age of gestation (AOG), the embryo has the definite form of a human. Refinements to all systems are also continuing at this period.

  1. NERVOUS: The spinal cord stops at the end of vertebral column.
  2. SENSORY: The taste buds are already initiating its development. Eyelids are already fused and the ears already achieve their final form but still are low-set.
  3. CARDIO and RESPI: The heart is separated into four chambers and heart is now detected using an ultrasound device. With regards to the respiratory system, additional branching of the bronchi is noted at this time.
  4. DIGESTIVE: The final form of the stomach is already observed at 8 weeks AOG. The lips are fused but the intestines are still contained in the umbilical cord.
  5. GENITOURINARY: In the presence of a Y chromosome, the testes’ development is initiated. In cases where the Y chromosome is absent, the ovaries will then develop. The appearance of the external genitalia has its slight differentiations; however, the male and female external reproductive organs still appear quite similar.
  6. MUSCULOSKELETAL: By the end of the eighth week, the webbed fingers and the toes are now distinct. Ossification of the bones is initiated and the joints resemble those of adults.
  7. INTEGUMENTARY: The auricles of the low-set ears are beginning to assume its final shape.

FETAL PERIOD

The fetal period is the longest phase of the prenatal development. This period starts at 9 weeks after conception takes place and ends with the birth of the baby. At this point, all the major systems are already present in their basic form. Structural and functional growth are noted at this time so as the refinements necessary for on all organ systems.

Week 10 (CRL= 61 mm)

By 10 weeks AOG, the fetus now weighs about 14 g.

  1. NERVOUS: Less head flexion is observed.
  2. SENSORY: The fused eyelids are still close and the top of the external ear is now situated slightly below the eye level.
  3. CARDIO and RESPI: The heartbeat can be possibly detected using a Doppler transducer. The blood is produced in the spleen and lymphatic tissues.
  4. DIGESTIVE: The intestines are no longer contained in the umbilical cord. These structures are now situated within the abdominal cavity. The digestive tract is already patent from the mouth (oral cavity) to the anus.
  5. GENITOURINARY: The kidneys are already in their adult position by the tenth week. The external male and female genitalia have achieved their different appearances but they are still easily confused.
  6. MUSCULOSKELETAL: The toes are already distinct and the soles are now facing each other.
  7. INTEGUMENTARY: By the tenth week, the fingernails are now developing and the tooth buds for the permanent teeth are already forming below the primary teeth.

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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