HUMAN PRENATAL DEVELOPMENT
TEACHER PORTAL
Modeling the Miracle: Tracking Prenatal Development Over Time
Unlike most CELLs, this activity will span the entire Human Prenatal Development CELL. Each week in the lab, you will use data tables and graphs that provide developmental milestones to follow several parameters, including fetal mass and length, limb and organ development, chances of survival outside the womb, etc.
This experience will condense the 36-week normal human gestation period into four weeks, with model measurements taken at approximately weeks 7, 14, 21, and 28 weeks of development.
Human Prenatal Development: Investigation 1 - Human Chromosomes
In Investigation One, you will learn that humans have 23 pairs of chromosomes. One of these 23 pairs determines the sex of the individual and can be detected by a microscopy technique referred to as a karyotype.
During this Investigation, you will:
- Use a microscope to examine the chromosomes of a human male and a human female.
- Observe that all but the sex pair of chromosomes appear identical for the male and female individuals
- Conclude that while female have two X chromomes in the sex pair (XX), the male sex pair contains one X and a smaller Y chromosome (XY).
Human Prenatal Development: Investigation 2 - Gamete Formation (Reduction Division)
In Investigation Two, you will observe how reduction division (meiosis) creates haploid gametes, containing only half of each of the 23 chromosome pairs.
During this Investigation, you will:
- Learn that while all other body cells (somatic cells) contain 23 pairs of chromosomes (thus 46 chromosomes total), these pairs are separated by reduction division during meiosis.
- The resultant haploid cells contain only one of each original chromosome pair.
- These haploid cells are called gametes; they contain one of each of the 23 human chromosomes and are referred to as spermatozoa (sperm cells) in males and ova (egg cells) in females.
- The male and female gametes combine at fertilization to produce a new individual diploid cell (called a zygote) containing 23 chromosome pairs, which are thus able to perform mitosis and grow rapidly.
Human Prenatal Development: Investigation 3 - Fertilization and Embryo Formation
In Investigation Three, you will follow the initial series of events that occur when male and female gamete cells (spermatozoa and ovum fuse, forming a zygote. This is followed by a well-
understood sequence of mitotic cell divisions that form a human embryo.
During this Investigation, you will:
- Examine human spermatozoa and ova under the microscope.
- Learn about the defined stages of embryonic development.
- Study how the growing embryo eventually reaches the fetal stage of development in the 10th week of pregnancy and is referred to as a fetus from that point forward.
- Observe that by the 12th week of pregnancy, the fetus nearly fills the entire uterus.
Human Prenatal Development: Investigation 4 - Fetal Development and Birth
In this Investigation, you will follow the developing fetus through the second and third trimester of development.
During this Investigation, you will:
- Follow the development of fetal organ systems
- Learn that the baby may survive premature birth as early as the end of the sixth month of pregnancy.
- examine life-size anatomical models of a full-term pregnancy.
- Learn how ultrasound works and how it permits physicians to follow fetal development.
Human Prenatal Development
Introduction and Background Reading
