Cell proliferation in the embryonic quail uropygial gland during placode stage to lumen formation

Abstract

The uropygial gland is one of the epidermal derivatives in birds. In the beginning of the morphogenesis of the uropygial gland of the quail embryo, placode formation occurs: Epidermal basal cells remain cuboidal until day 7 of incubation. At day 8 they begin to elongate, become columnar, and develop placode-like structure at day 9. To examine the proliferative activity of the epidermal basal cells, we recorded positions of [3H]-thymidine-labelled nuclei in serial sections by autoradiography (ARG) using a digitizer and a microcomputer. The distribution pattern of labelled nuclei was reconstituted and redisplayed on the cathode ray tube (CRT) as two-dimensional computer graphics. Three-dimensional reconstitution of the same serial sections revealed that cuboidal basal cells in the presumptive uropygial placode became columnar. Unlike the feather and scale placodes, the uropygial placode possessed no resting period of DNA synthesis. The labelling index of the uropygial placode increased considerably compared with that of nonplacode epidermis. No dermal condensation was observed beneath the uropygial placode.

The uropygial gland of the monk parakeet Myiopsitta monachus: Histology, morphogenesis, and evolution within Psittaciformes (Aves)

“…The time of onset of the morphogenesis of the UG is known for several species. For example, they appear at day eight in zebra finches ( Taeniopygia guttata , Passeriformes) and pigeons (Columbiformes), at day ten in chickens ( Gallus gallus , Galliformes), Japanese quail ( Coturnix coturnix , Galliformes), and Peking ducks ( Anas platyrhynchos , Anseriformes), at day 12 in budgerigars ( Melopsittacus undulatus , Psittaciformes), and at day 13 in Laysan albatross ( Phoebastria immutabilis , Procellariiformes; Bride & Gomot, ; Jacob & Ziswiler, and bibliography cited therein; Fukui, ; Fukui, ; Rehorek et al, ). However, only the characterization of the developmental stages of some of these species (i.e., Gallus gallus , Hamburger & Hamilton, ; Coturnix coturnix , Ainsworth, Stanley, & Evans, ; Phoebastria immutabilis , Rehorek, Smith, & Beeching, ) are available in the bibliography, including our species under study ( Myiopsitta monachus , Carril & Tambussi, ), and it is on these species that we base our comparisons.…”

“…Despite a plethora of studies about the size, morphology, histology, secretion, and function of the UG of several bird species (e.g., Chiale, Carril, Montalti, & Barbeito, ; Golüke & Caspers, ; Harem et al, ; Haribal, Dhondt, Rosane, & Rodriguez, ; Martín‐Vivaldi, Ruiz‐Rodríguez, Soler, Peralta‐Sánchez, & Méndez, ; Mohamed, ; Møller, Erritzøe, & Rózsa, ; Moreno‐Rueda, ; Moyer, Rock, & Clayton, ; Sadoon, ; Sawad, ; Soler, Peralta‐Sánchez, Martín‐Plateros, Martín‐Vivaldi, & Martínez‐Bueno, ), little is known about its morphogenesis. Contributions on this topic are restricted to a few old studies focused on chickens, quails and ducks (e.g., Bride & Gomot, ; Fukui, ; Fukui, ; Fukui, ; Wagner & Boord, ), and the recent article on the Laysan albatross Phoebastria immutabilis (Rehorek, Wu, Smith, & Beeching, ).…”