This stage is known as the sporocyst and it forms a central body in the snails digestive gland that extends into a brood sac in the snails head, muscular foot and eye-stalks. It is in the central body of the sporocyst where the parasite replicates itself, producing many tiny embryos (redia). These embryos move to the brood sac and mature into cercaria. Life cycle adaptations
Trematodes have a large variation of forms throughout their life cycles. Individual trematode parasites life cycles may vary from this list. They have five larval stages along with the cystic and fully matured adult phases. Trematodes are released from the definitive host as eggs, which have evolved to withstand the harsh environment
Released from the egg which hatches into the miracidium. This infects the first intermediate host in one of two ways, either active or passive transmission. The first host is normally a mollusk. a) Active transmission has adapted for dispersal in space as a free swimming ciliated miracidium with adaptations for recognizing and penetrating the first intermediate host. b) Passive transmission has adapted for dispersal in time and infects the first intermediate host contained within the egg. The sporocyst forms inside the snail first intermediate host and feeds through diffusion across the tegument. The rediae also forms inside the snail first intermediate host and feeds through a developed pharynx. Either the rediae or the sporocyst develops into the cercariae through polyembryony in the snail. The cercariae are adapted for dispersal in space and exhibit a large variety in morphology.
Cortical desmoid (also called tug lesion or periosteal desmoid) is an irregularity of the distal femoral cortex caused by repetitive stress at the attachment of the adductor magnus aponeurosis. It is most commonly seen in adolescents and is usually asymptomatic. It is a benign and self-limiting lesion. References
Gould CF, Ly JQ, Lattin GE, Beall DP, Sutcliffe JB (2007). "Bone tumor mimics: avoiding misdiagnosis". Curr Probl Diagn Radiol. 36 (3): 124–41. doi:10.1067/j.cpradiol.2007.01.001. PMID 17484955.