Development Review Worksheet Key

I. Process of Fertilization

• Fertilization: Union of the nucleus of egg and sperm.
• Location: Occurs in the fallopian (uterine) tube.
• Chromosomes in Gametes: 23 (haploid).
• Chromosomes in Fertilized Egg: 46 (diploid).

II. Embryonic Development

Section 2: Definitions

• Zygote: Fertilized egg, first cell of a new individual, single diploid cell.
• Embryo: Earliest developmental stage from the first cell division (zygote) to about 8/10 weeks.
• Fetus: From about eight weeks GA (10 weeks from LMP) until birth.

Section 3: Early Embryonic Events

• Event A: Sperm penetration (fertilization).
• Resulting Cell from Event A: Zygote.
• Process B: Cleavage.
• Embryonic Structure B1: Blastocyst.
• Completed Process C: Implantation.

Diagram Labels:

• Blastocyst
  • Cleavage
  • Fertilization
  • Gastrula
  • Implantation
  • Morula
  • Zygote

Section 4: Derivative Structures from Embryonic Layers

Ectoderm

• Epidermis of skin, hair, nails, skin glands, sense receptors, inner ear, cornea, lens of eye, tooth enamel.
• Central nervous system (brain and spinal cord), epithelium of pineal and pituitary glands.

Mesoderm

• Notochord, skeletal system, muscular system, circulatory and lymphatic systems, excretory system, reproductive system.

Endoderm

• Epithelial lining of digestive and respiratory systems, liver, pancreas, thyroid, parathyroids, thymus.

III. Fetal Development

Section 5: Fetal Development Events

• Labor: Culmination of pregnancy with birth of newborn infants from uterus.

Section 7: Phases of Parturition (Labor)

1. Dilation: Beginning of labor until full cervical dilation (~10 cm); longest phase.
2. Expulsion: Full dilation to delivery; baby moves through cervix and vagina (birth).
3. Placental: Expulsion of placenta; follows delivery.

Section 8: Labor Feedback Loop

• Type: Positive feedback loop.
• Initial Stimulus: Infant head putting pressure on cervix.
• Oxytocin: Increases.
• Uterine Contractions: Increase.
• Stop Event: Baby born; no longer pressure against cervix.

IV. Additional Concepts

Section 9: Stem Cell Descriptions

• Stem Cells: Master cells; building blocks of organ tissue, blood, and immune system.
• Pluripotent: Differentiate into all derivatives of three primary germ layers.
• Multipotent: Produce limited number of cell types, such as blood stem cells.
• Bone Marrow Stem Cells: Multipotent stem cells in bone marrow.
• Cord Blood: Multipotent blood remaining in placenta and umbilical cord.

Section 10: STD and Disease/Disorder Descriptions

• Breast Cancer: Leading cause of cancer death in women; starts in mammary tissues.
• Gonorrhea: Bacteria causing painful urination in men, often asymptomatic in women.
• Human Papilloma Virus (HPV): Most common STI; can cause genital warts and increase cervical cancer risk.
• Ovarian Cancer: Begins in female organs that produce eggs.
• Syphilis: Bacteria causing painless sore, leading to rash and potentially serious complications.
• Prostate Cancer: Occurs in prostate, wraps around urethra.
• Genital Herpes: Virus causing genital sores, fever, and increased cervical cancer risk.
• Testicular Cancer: Most common cancer in young men; occurs in seminiferous tubules.
• Chlamydia: Bacteria causing painful urination and intercourse, discharge.