Apicomplexan parasites such as Eimeria, Neospora, Toxoplasma and Plasmodium are microorganisms that cause the most devastating infectious diseases of livestock and humans. These pathogenic protozoa have complex life cycles alternating between asexual multiplication and sexual reproduction (gametogenesis). During sexual development the male gametocytes (micro-) fuse with the female gametocytes (macrogametocytes) to form zygotes, which develop a resistant wall and are termed oocysts. The oocyst wall is a robust structure resistant to mechanical damage and is impermeable to water-soluble substances, making the control of malaria, toxoplasmosis and coccidiosis extremely difficult. Previously, we have shown that the mechanisms of oocyst wall formation in Eimeria maxima are analogous to the sclerotization of insect cuticles and involves protein-tyrosine crosslinks. Moreover, we and others have provided evidence for a structural role for lipids in the oocyst wall that makes them resistant to environmental stress. However, exactly how the parasite assembles these molecules into an impervious oocyst wall while maintaining the ability to acquire nutrients needed for development into an infectious cyst form remains an open question. Therefore, we harvested and maintained viable E. maxima gametocytes in vitro for several hours to study the mechanisms of nutrient intake by visualising the structure and dynamics of the parasite surface membrane. We used scanning electron microscopy with live-cell imaging and a series of endocytosis assays to study uptake and the intracellular location of internalised particles. Furthermore, three-dimensional confocal microscopy was used to determine the subcellular location of the cytoskeletal elements in early oocysts in vitro. Finally, we used LC-MS/MS-based shotgun proteomics for the analysis of the wall forming body proteome in E. maxima. The results reported here reveal valuable insights into the mechanisms by which the parasite is able to acquire nutrients essential for development, transport organelles and at the same time synthesise the impervious oocyst wall.