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Semen analysis plays a key role in diagnostics of male infertility. Semen analysis should be done according to WHO guidelines (1999), which are currently under revision. Standard procedures of semen analysis include evaluation of sperm concentration, motility, morphology, and vitality as well as determination of round cells, leukocytes, and sperm antibodies. Analysis of biochemical markers is optional. Several methods of sperm preparation are available for assisted reproduction procedures. Patients should be asked to remain abstinent for at least 48 h and a maximum of 7 days prior to ejaculation.Special focus has to be on quality control programs in andrological laboratories based on WHO guidelines. Only by means of standardized semen analysis the andrologist is capable of counseling infertile couples and diagnosing andrological deficits to finally determine therapeutic strategies including techniques of assisted reproduction.

The development of fibrous nonunions following orthognathic surgery is thought to result from an interaction of biomechanical stress and the differential and more rapid migration of fibroblasts compared to osteoblasts into the wound site during healing. The present study was designed to test this hypothesis through the manipulation of guided tissue regeneration and osteotomy fixation techniques in an experimental rabbit model.Bilateral critical size (4 mm) defects (n = 24) were produced in the maxillae of 12 adult New Zealand White rabbits. The maxillary segments were rigidly or nonrigidly fixed using bone microplates and screws or osteosynthetic wires. The defects were then covered with a resorbable collagen membrane or left uncovered. The rabbits were followed for 4 weeks with serial dorsoventral and lateral oblique cephalographs and the maxillae were then harvested for histological analysis.Radiographic and histomorphometric analysis revealed that rigidly fixed defects, covered with membrane, showed the most rapid and organized new bone formation. The rigidly fixed defects with membrane averaged approximately 40% more new bone in the osteotomy site than the rigidly fixed defects with no membrane. Nonrigidly fixed defects with no membrane also showed an ingrowth of fibroblasts and fibrous nonunions.These results suggest that an interaction between the decreased fibrous tissue ingrowth through guided tissue regeneration and osteotomy segment stability from rigid fixation prevented postoperative fibrous nonunions and facilitated new bone regeneration and osteotomy site healing in this rabbit model.