What term describes instances when ridge units are present but do not fuse to create friction ridges?

The term that describes instances when ridge units are present but do not fuse to create friction ridges is dysplasia. This concept pertains to the abnormal development of fingerprints where the characteristics of skin and growth patterns deviate from the norm. In dysplasia, the lack of fusion of ridge units results in the absence of the typical organized structure of friction ridges that one would expect in normal fingerprint formation. Dysplastic features may lead to variations in the appearance and functionality of fingerprints, highlighting developmental irregularities.

In contrast, hyperplasia involves an increase in the number of cells due to an increase in cell division, which is not specifically related to the fusion or formation of friction ridges. Apocrine refers to a type of gland or secretion and does not pertain to fingerprint development, as does the term mutation, which typically describes a change in genetic material that may or may not affect phenotypic traits like fingerprints. Therefore, dysplasia is the correct term to identify the specific condition of ridge units failing to fuse into established friction ridges.