title: Histopathological study of ovaries of Rhipicephalus sanguineus (Acari: Ixodidae) exposed to different thymol concentrations.
abstract: Thymol is a monoterpene with proven acaricide action for several tick species. In addition to killing these ectoparasites, thymol can also reduce oviposition and egg hatch rate. However, the effects of thymol on the morphophysiology of tick ovaries are still unknown. Thus, the aim of this study was to evaluate the morphophysiological changes caused by this active principle in ovaries of Rhipicephalus sanguineus after a 6-day feeding period, through the application of morphohistochemical techniques. After the feeding period, a total of 50 females were divided into five groups and immersed in the following solutions: (I) distilled water (control), (II) 30% ethanol (control), (III) 1.25 mg/mL thymol, (IV) 2.5 mg/mL thymol, and (V) 5.0 mg/mL thymol. The experimental groups were kept in a climatic chamber (27 ± 1 °C; RH 80 ± 10%) for 5 days. After this period, morphological (hematoxylin/eosin) and histochemical (von Kossa) techniques were applied after remotion of the ovaries. The morphological results revealed large vacuoles in germ cells at different developmental stages and invaginations that represent deformations in the chorionic membrane. From the results obtained in this study, it was concluded that thymol interfered with the development of oocytes, which showed degeneration signs. The treatment containing 5.0 mg/mL thymol affected more accentuately the morphological development. Moreover, thymol also altered the calcium content of yolk granules, which generally showed an intense staining for this element.
authors.affiliation: Programa de Pós-graduação em Comportamento e Biologia Animal, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n - Campus Universitário Bairro Martelos, 36036-330, Juiz de Fora, MG, Brazil, renata.matosjf@gmail.com.
authors.forename: Renata
authors.initials: R
authors.lastname: da Silva Matos
authors.forename: Erik
authors.initials: E
authors.lastname: Daemon
authors.forename: Maria Izabel
authors.initials: MI
authors.lastname: Camargo-Mathias
authors.forename: Karim Christina Scopinho
authors.initials: KC
authors.lastname: Furquim
authors.forename: Bruno Rodrigues
authors.initials: BR
authors.lastname: Sampieri
authors.forename: Rafael Neodini
authors.initials: RN
authors.lastname: Remédio
authors.forename: Laryssa Xavier
authors.initials: LX
authors.lastname: Araújo
authors.forename: Tatiane Pinheiro Lopes
authors.initials: TP
authors.lastname: Novato
mesh_terms: D056810:Acaricides / Q000494:pharmacology*; D000818:Animals; D001096:Arachnid Vectors / Q000033:anatomy & histology / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D009865:Oocytes / Q000187:drug effects; D010053:Ovary / Q000033:anatomy & histology / Q000187:drug effects; D010058:Oviposition / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology; D011817:Rabbits; D048508:Rhipicephalus sanguineus / Q000033:anatomy & histology / Q000187:drug effects*; D013943:Thymol / Q000494:pharmacology*
chemical_list: D056810:Acaricides; D010936:Plant Extracts; D013943:Thymol