The ultrastructure of the chorioallantoic placenta of the lesser bush baby (Galago senegalensis) has been studied. The placenta was shown to be of the diffuse, epitheliochorial and adeciduate type. The trophoblasts of the chorionic villi, other than those lining the chorionic vesicles, were characterized by the presence of many lipid droplets. In the later stage of gestation, the fetal capillaries indented the trophoblastic epithelium reducing the distance between fetal and maternal circulations. In addition chorionic vesicles were observed. The trophoblasts lining the chorionic vesicles have outward bulging apical surfaces. There are clefts between these cells and this region is occupied by microvilli of adjacent cells. Several layers of fusiform cells that did not extend up into the cores of the chorionic vesicle villi formed the outer component of the vesicular wall. Granulated cells were observed within the maternal connective tissue and their possible role is discussed

In an endeavour to comprehend the mechanisms of vertebrate embryonic development including how the embryo attains its form and structures, biologist have over the years devised a number of methods. In all the techniques employed, the choice of the method is largely determined by the question to be answered amongst other factors. This review looks at the various methods that have been developed, ranging from the use of simple lenses through histological sectioning and direct manipulation to the use of biochemical probes and extracts