stratum

Examples of stratum in the following topics:

• Structure of the Skin: Epidermis

  • The epidermis includes five main layers: the stratum corneum, stratum lucidium, stratum granulosum, stratum spinosum, and stratum germinativum.
  • The stratum basale, also called the stratum germinativum, is the basal (base) layer of the epidermis. 
  • From the stratum basale, the keratinocytes move into the stratum spinosum, a layer so called because its cells are spiny-shaped cells. 
  • Once the keratinocytes leave the stratum granulosum, they die off and help form the stratum lucidum.
  • From the stratum lucidum, the keratinocytes enter the next layer, called the stratum corneum (the horny layer filled with cornified cells). 

• What is Skin?

• Blood Supply to the Epidermis

  • The blood vessels in the dermis provide nourishment and removes waste from its own cells and from the Stratum basale of the epidermis.
  • The blood vessels in the dermis provide nourishment and waste removal from its own cells as well as from the Stratum basale of the epidermis.

• Lab 2: Sampling Experiment

  • Use 25% of the restaurants from each stratum.
  • Use 25% of the restaurants from each stratum.

• Three sampling methods (special topic)

  • Stratified sampling is especially useful when the cases in each stratum are very similar with respect to the outcome of interest.
  • Why would it be good for cases within each stratum to be very similar?
  • We might get a more stable estimate for the sub-population in a stratum if the cases are very similar.
  • Strati ed sampling requires observations be sampled from every stratum.
  • In the middle panel, stratified sampling was used: cases were grouped into strata, and then simple random sampling was employed within each stratum.

• Optional Collaborative Classrom Exercise

  • Create a cluster sample by considering each state as a stratum (group).

• Amnion Development

  • This cavity is roofed in by a single stratum of flattened, ectodermal cells called the amniotic ectoderm.

• Skin Color

  • The deepest of the epidermal layers is called the stratum basale or stratum germinativum. 
  • The amount of carotene found in the stratum corneum of the epidermis and the deepest layer of the skin, the hypodermis. 

• Blastocyst Formation

  • The outer stratum forms a syncytium, which is a layer of protoplasm studded with nuclei but showing no evidence of subdivision into cells (termed the syncytiotrophoblast).

• Lab 1: Normal Distribution (Lap Times)

  • Use a Stratified Sampling Method by Lap (Races 1 – 20) and a random number generator to pick 6 lap times from each stratum.