Fred the Fireman burned his left arm during a recent heroic rescue. The most important epidermal stratum involved in healing by regeneration of new skin is the:

A. mesenchyme
Mesenchyme is a type of embryonic connective tissue from which all adult connective tissues develop. It has a fluid matrix and undifferentiated cells.

B. osteochondral
This is nota recognized fetal stem tissue type. It refers more to regions with both bone and cartilage precursors, but it's not a stem connective tissue.

C. mucous
Mucous connective tissue, found in the umbilical cord (Wharton's jelly), is another type of fetal stem connective tissue.

D. A & B
Mesenchyme is correct, but osteochondral is not a true fetal stem connective tissue.

E. A & C
Both mesenchyme and mucous connective tissue are fetal connective tissues with stem-like properties.

A. medullary cavity
This cavity holds marrow (red or yellow), not cartilage.

B. epiphyseal line
The epiphyseal line in adults is a remnant of the epiphyseal plate, but does not contain cartilage.

C. ends of the bones
Both Peter and Paul have articular hyaline cartilage at the ends of long bones for joint function.

D. epiphyseal plate
Only children like Peter have an epiphyseal plate (growth plate), which is made of hyaline cartilage. This area allows for bone lengthening during growth and becomes the epiphyseal line in adults like Paul.

E. in periosteum
The periosteum is a connective tissue membrane around bone-not cartilage.