The current investigation was carried out to record the final stages of the development of both middle and distal parts of quail ceca, Coturnix coturnix japonica to understand the role of ceca in digestion, immune system, and absorption. The cellular and subcellular structures, including epithelial cell height, microvillus surface area, the proportion of goblet cells, the thickness of muscle layer, and cecum diameter showed great variations during the development. An undeveloped smooth muscularis mucosa was observed for the first time on the ED5. Primordia of glands were observed on the ED7. On the ED15, the middle part exhibited two shapes of mucosal villi: tongue-shaped villi and U-shaped. The plicae and crypts of Lieberkühn were demonstrated on the hatching day. The lymphatic tissues appeared in the wall of both parts of the ceca at the 4 weeks of age. Scanning electron microscopy revealed a great difference in the mucosal surface between different regions. Telocytes were observed in-between the muscle fibers and formed a network during the post-hatching period. Because of fermentation and other bacterial or chemical processes that have been shown to occur in the ceca, this study supports two hypotheses: the cecal development is related to diet and the cecal epithelium act as a site for primary absorption of nutrients or for re-absorption of electrolytes or amino acids derived from the urine.

The extant lungfish, including three genera, the Australian, South American and African lungfishes, retain a dentition that appeared first in the Devonian, in some of the oldest members of this group. The dentition consists of permanent tooth plates with persistent cusps that appear early in development of the fish. The cusps, separate early in development, form ridges that are arranged in a radiating pattern, and fusion of the cusps to each other and to the underlying jaw bone produces a tooth plate. The lungfish dentition is based on a template of mantle dentine that surrounds bone trabeculae enclosed in the tooth plate. The mantle layer is covered by enamel. In most derived dipnoans, this framework encloses two further forms of dentine, known as interdenteonal and circumdenteonal dentines. The tooth plates grow in area and in depth without evidence of macroscopic resorption of dentines or of enamel. Increase in size and changes in shape of lungfish tooth plates is actually achieved by a process involving microscopic remodelling of the bone contained within the margin of each tooth plate, and the later addition of new dentines and enamel within and around the bone. This is accomplished without creating weakness in the structural integrity of the tooth plate and bone complex, and proceeds in line with growth and remodelling of the jaw bones attached to the tooth plates.