Embryonic age

Examples of Embryonic age in the following topics:

• Fifth Through Eighth Weeks of Development

  • Embryonic age measures the actual age of the embryo or fetus from the time of fertilization.
  • Thus, the first week of embryonic age is already week three counting with gestational age.
  • The number of the week (used here) is one more than the actual age of the embryo/fetus.
  • The features are consistent with a developmental age of seven weeks (the ninth week of menstrual age).
  • This embryo is about five weeks old (or from the seventh week of menstrual age).

• Development of the Extraembryonic Coelom

  • An artificially colored image of the contents in the cavity of the uterus seen at approximately 5 weeks of gestational age by obstetric ultrasonography.

• Embryonic and Fetal Bone Formation

  • Embryonic/fetal development proceeds from rostral (nose and mouth area) to caudal (posterior).
  • Embryonic mesenchymal cells (MSC) condense into layers of vascularized primitive connective tissue.

• Bilaminar Embryonic Disc Development

• The Middle Years

  • Middle age is the period of age beyond young adulthood but before the onset of old age.
  • Census lists middle age as including people aged from 35 to 54, while developmental psychologist Erik Erikson argues that middle adulthood occurs from the age of 40 until 65.
  • Middle-aged adults often show visible signs of aging such as the loss of skin elasticity and the graying of hair.
  • However, people age at different rates and there can be significant differences between individuals of the same age.
  • However, the majority of middle-age people in industrialized nations can expect to live into old age.

• Dividing the lifespan

  • Human life is often divided into various age spans, like the following:
  • In many countries, such as Sweden, adulthood legally begins at the age of eighteen.
  • This is a major age milestone that is marked by significantly different attitudes toward the person who undergoes the transition.

• Effects of Aging on the Integumentary System

  • Intrinsic and extrinsic aging are terms used to describe cutaneous aging of the skin and other parts of the integumentary system.
  • The effects of intrinsic aging are caused solely by internal factors.
  • Sometimes called chronological aging, intrinsic aging is an inherent degenerative process due to declining physiologic functions and capacities.
  • As skin ages, it becomes thinner and more easily damaged.
  • Photodamage implies changes beyond those associated with aging alone.

• Embryonic Development

• Development of Nervous Tissue

  • Embryonic neural development includes the birth and differentiation of neurons from stem cell precursors.

• Animal Reproduction and Development