RESUMO
The egg and larval stages of Gnathostoma turgidum were examined using light microscopy. Fertilized uterine eggs are 65.97 long and 32.28 wide, oval, brownish, with two cap-like thickenings. The eggshell surface is covered with numerous irregularly shaped pits of various sizes and depths. A sheathed second-stage larva emerges from the egg, measures 178 x 9; the sheath measures 243 x 21. Development to early third-stage larva in the coelomic cavity of cyclopoid copepods is similar to that described for other gnathostome species. After 10 days at 27 degrees C, the larvae undergo a molt (the second for gnathostomes) and develop to early third stage. The body of this stage measures 412.3 x 40.1, with evident hemispherical cephalic bulbs. Cephalic bulbs measure 25 x 40, armed with four transverse rows of sharp hooklets. The average number of hooklets in each row is 31, 34, 37, and 42, respectively. The whole body is covered with 193 transverse rows of small single-pointed cuticular spines. One pair of cervical papillae and an excretory pore are present on the anterior part of the body. On the other hand, potential species-specific features regarding the latter larval stage are discussed. Finally, some G. turgidum life cycle considerations are portrayed.
Assuntos
Gnathostoma/crescimento & desenvolvimento , Estágios do Ciclo de Vida , Animais , Gnathostoma/anatomia & histologia , Larva/anatomia & histologia , Larva/crescimento & desenvolvimento , MicroscopiaRESUMO
In order to clarify the role of Gnathostoma turgidum as an etiological agent involved in human gnathostomiasis in Mexico, establish the taxonomic identity of the advanced third-stage larvae (AdvL(3)), and contribute to the knowledge of its life cycle, experimental host infections, examination of potential natural hosts, and morphological comparisons were carried out. Examination of ten species of potential hosts at San Pedro las Playas and Tres Palos Lagoon in Guerrero state, Mexico revealed that two (Kinosternon integrum and Rana zweifeli) were infected by 15 AdvL(3) of G. turgidum. A specific identity was obtained comparing these larvae with those recovered from hosts experimentally infected. The AdvL(3) measured 1.6 mm in length, with two cervical papillae (both in 12th row) and an excretory pore on the 19th row. The average of cephalic hooklets, from first to fourth row, was 30.8, 34.0, 36.7, and 39.6, respectively. This is the first record of AdvL(3) of G. turgidum in America, and it represents a significant contribution for the understanding of the life cycle of this species.