Organ Transplantation and Assisted Reproduction

Posted on Nov 29, 2024 in Biology

Transplantation

Transplanting: Replacement of a diseased organ or tissue that endangers a person’s life. Donor: Usually a deceased person (brain dead) or a living person. Spanish Legislation: 1. Defines brain death as a scientific, legal, and ethical concept. 2. Respects the deceased’s will regarding donation. 3. Death diagnosis is made by an independent medical team. 4. Ensures altruism and non-commercialization. 5. Guarantees donor anonymity. 6. Applies medical criteria for organ distribution.

Types of Transplantation

  • Autotransplantation/Autograft: Donor and recipient are the same, eliminating rejection risk.
  • Isograft: Donor and recipient are identical twins, eliminating rejection risk.
  • Xenotransplantation: Donor and recipient are of different species, posing a high rejection risk.
  • Allogeneic Transplantation: Donor and recipient are of the same species but not genetically identical, posing a rejection risk.

Transplantation Challenges

  1. Rejection: Donor and recipient tissues are incompatible. Immunosuppressants are used to prevent rejection.
  2. Organ Shortage: Technical impossibility of obtaining certain organs and tissues.

Donatable Tissues and Organs

Lungs, heart, kidney, liver, pancreas, skin, cornea, bone, heart valves, blood vessels, pancreatic cells, bone marrow (produces blood cells; transplantation can cure serious diseases), and umbilical cord blood. Note: The spinal cord cannot be replaced.

Human Reproduction and Development

Fertilization: The union of an egg and sperm, occurring within the fallopian tube, forming a zygote.

Development: Embryonic development ends at birth, while postnatal development begins at birth.

Early Embryonic Development Stages

  1. Sperm fertilizes egg in the fallopian tube, forming a zygote.
  2. Zygote travels to the uterus, dividing.
  3. Cells divide to form a 32-cell embryo (morula).
  4. A cavity forms inside the morula, creating a hollow ball (early blastocyst).
  5. Cells condense within the blastocyst (late blastocyst).
  6. Embryo implants in the uterine wall (endometrium).

Key Developmental Points

  1. Embryo implantation in the endometrium.
  2. Nervous system begins forming at 14 days.
  3. Organs begin functioning at about 2 months (fetus).

Assisted Reproduction

Techniques used to overcome difficulties in conceiving.

  1. Artificial Insemination: Sperm is artificially introduced into the female genital tract.
  2. In Vitro Fertilization and Embryo Transfer (IVF-ET): Egg fertilization occurs outside the body.
    1. Egg retrieval: Hormone treatment stimulates egg production.
    2. Fertilization: Eggs are fertilized by sperm in a lab.
    3. Embryo transfer: Embryo is placed into the uterus.

Stem Cells and Regenerative Medicine

Stem Cells: Unspecialized cells capable of multiplying and differentiating into specialized cells.

Types of Stem Cells

  1. Totipotent (zygote and blastocyst): Can form a complete individual.
  2. Pluripotent: Can form any cell type.
  3. Multipotent: Can form some cell types.
  4. Oligopotent: Can form one or a few cell types.

Regenerative Medicine: Produces tissues or organs to replace damaged ones using embryonic, adult (tissue), or induced pluripotent stem cells (iPSCs).

Cloning

Cloning: Creating a genetically identical copy of a living entity.

Nuclear Transfer: A cloning technique.

  1. A differentiated cell is obtained from the individual to be cloned.
  2. An egg is obtained from a female.
  3. The egg’s nucleus is removed.
  4. The differentiated cell’s nucleus is transferred to the egg.
  5. The cell is cultivated to develop into an embryo.
  6. The morula is transferred to a surrogate mother’s uterus.
  7. After gestation, a new individual (clone) is born.

Bioethics

Bioethics: A branch of ethics addressing moral issues in biomedicine.