title: [The thyroid gland of humpback salmon (Oncorhynchus gorbuscha) fry and of humpback and cherry salmon (Oncorhynchus masu) hybrids during smoltification].
abstract: Thyroid gland follicular cells were studied morphofunctionally on different stages of juvenile humpback salmon migration from the spawning sites into the sea. Salmon hybrids kept in laboratory conditions in fresh and salt water were exposed to the same examination. Juvenile humpback salmon fished out from the river mouth, when coming to the sea water had significant increase of follicular epithelium height and decrease of follicular diameter and amount of the deponated colloid. Thyroid glands follicle topography of hybrids is close to those of juvenile humpback salmon although it is more compact in hybrids. Completely formed follicles were found in three-month-old fish. Microscopic and morphometric studies revealed the increase of thyroid gland activity in hybrids in April: follicular diameter grew smaller, epithelial height significantly increased and amount of colloid in the follicles decreased. In May increased activity of the gland remained and went smaller in June. Ten days after hybrids transferation into the sea water activity of the gland cells significantly increased. Thus, thyroid gland activity is an important characteristics of smoltification both for the juvenile salmon from natural population and hybrids kept in laboratory conditions.
authors.forename: A A
authors.initials: AA
authors.lastname: Maksimovich
authors.forename: S A
authors.initials: SA
authors.lastname: Shevchuk
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D005260:Female; D007814:Larva / Q000033:anatomy & histology; D008297:Male; D017683:Oncorhynchus / Q000033:anatomy & histology*; D012474:Salmon / Q000033:anatomy & histology*; D013961:Thyroid Gland / Q000033:anatomy & histology*