Advances in Medicine and Biology. Volume 169 begins with a focus on psoriasis, a chronic inflammatory skin disease that displays autoimmune traits with strong genetic predispositions. Often, psoriasis is associated with significant physical or psychosocial burden, poor quality of life and significant long-lasting impairments. Following this, the authors discuss matrix metalloproteinases, multi-domain proteins with activities regulated by tissue inhibitors of metalloproteinases. Cyptorchidism, a congenital pathological condition characterized by the failure of testes to descend to the scrotum, is also discussed. Exposure to environmental toxicants, pesticides, pharmaceuticals and drugs of abuse can lead to altered reproductive parameters like histopathology of reproductive organs, sperm morphology, altered hormone level, oxidative stress and inflammation. As such, the subsequent study deals with different toxicants and their routes of exposure. The role that endometriosis, polycystic ovary syndrome, endometrial polyps and uterine fibroids may play in female infertility is examined. The authors present three cases of twin pregnancy with complete hydatidiform mole and a coexisting normal fetus. The course of pregnancy, ultrasound findings, and histological and immunohistochemical characteristics are described along with the p57 status. In the closing study, the mode of action, indications, contraindications, side effects, drug-drug interactions and pharmacokinetic parameters of secnidazole are discussed in detail.