phenotype affects entity Harderian gland development abnormal Harderian gland morphology abnormal Harderian gland development aberrant formation or incomplete differentiation of the sebaceous gland located behind the eyeball that excretes fluid that facilitates movement of the nictitating membrane; in rodents, the Harderian gland originates from the nasal part of the conjunctival epithelium at E16 and forms a branched structure behind the eyeball; in contrast to the acinar morphology of the lacrimal gland, the Harderian gland has a tubulo-alveolar organization and is composed exclusively of one type of secretory cell; in primates, the HG is either absent or vestigial Note that the Harderian gland is found in all terrestrial vertebrate groups, including amphibia, reptiles, birds, and mammals. However, it appears to be absent in certain mammals such as bats, cows, horses, and higher primates. Though largely absent in the adult human, it is present in the fetal and neonatal stages Harderian gland dysgenesis MP:0013439 abnormal gland development