Pitkittäiskasvu

Pitkittäiskasvu, often translated as longitudinal growth, refers to the increase in length or height of an organism. This process is primarily driven by the division and elongation of cells in specific growth regions. In plants, pitkittäiskasvu occurs at the tips of roots and shoots, facilitated by apical meristems. These meristems contain undifferentiated cells that actively divide, producing new cells that then differentiate and elongate, pushing the plant body outwards.

In animals, pitkittäiskasvu is most evident in the skeletal system, particularly the long bones. Growth plates, also known as epiphyseal plates, located near the ends of long bones are responsible for this growth. Chondrocytes (cartilage cells) within the growth plates proliferate and then enlarge, causing the bone to lengthen. Hormones, such as growth hormone and thyroid hormones, play crucial roles in regulating this process. Pitkittäiskasvu typically ceases when the growth plates ossify, usually at the end of puberty. The rate and duration of pitkittäiskasvu are influenced by genetic factors, nutrition, and environmental conditions.