Figure 2

Transmission electron microscopy (TEM) of oviductal magnum from juvenile (10-week-old) and egg-laying adult (30-week-old) chickens. The oviductal magnum from the juvenile was simply composed of an epithelial layer toward the luminal surface and stroma cells underneath the epithelium (a-c). In the epithelium, numerous mitochondria (Mc) were observed (b). The adult oviductal magnum was composed of epithelia on the luminal surface and tubular gland cells (d-i). The secretory epithelia contained large masses of homogenously processed secretory granules (d, e). Tubular gland cells generally contained electron-dense granules in the tubular gland. Type A (tA) cells had homogenous electron-dense granules (d, f), type B (tB) cells contained low electron-dense granules (g), and type C (tC) cells possessed well developed GER cisternae and a Golgi complex to transform electron-dense granules to secretory granules (h, i). Ci, cilia; E, epithelium; G, Golgi complex; GER, granular endoplasmic reticulum; Mc, mitochondria; N, nucleus; S, stroma; Sg, secretory granule. Bars = 10 μm (a), 5 μm (b,c), 2 μm (d), 1 μm (f, g), and 100 nm (e, h, i).