¿Qué genera las enfermedades infecciosas?

How does pregnancy begin? a) a placenta forms in the uterus b) a sperm reaches an egg in the fallopian tubec) the blastocyst differentiates into two cell types d) contractions begin in the uterine wallapex

Describe two recent or ongoing space missions.

Which is a function performed by stem cells in the skin a. replacing lost skin cells b. making cells for the intestines c. growing new organs d. differentiating into brain cells plz apex