Cell proliferation in condensing scleral ectomesenchyme associated with the conjunctival papillae in the chick embryo.
نویسندگان
چکیده
The role of cell proliferation in the formation of scleral ectomesenchymal condensations underlying the conjunctival papillae was examined with in vivo tritiated thymidine labelling in chick embryos ranging in age from 8 days 0 h to 10 days 12 h. Percentages of labelled nuclei were determined in both ectomesenchyme and the deeper fibrous sclera for short-term and continuous tritiated thymidine incubations. During formation of the ectomesenchymal condensations the percentages of labelled nuclei were consistently higher within the condensations than in corresponding non-condensing ectomesenchyme between papillae. The consistent differences of labelling percentages observed within the condensing versus non-condensing ectomesenchyme were not found in the fibrous sclera at any stage. All areas of both the ectomesenchyme and fibrous sclera showed decreases in the percentages of labelled nuclei from 8 days 0 h to 10 days 12 h, although the decline in the ectomesenchymal condensations beneath papillae occurred more slowly than in areas between papillae. The data suggest that the conjunctival papillae directly influence the proliferation in the subjacent condensing ectomesenchyme but have no effect on the ectomesenchyme between papillae or any region of the deeper fibrous sclera. The observations of this investigation are discussed in relation to other studies of the development of the pre-ossicular mesenchyme.
منابع مشابه
The origin of the ectomesenchymal condensations which precede the development of the bony scleral ossicles in the eyes of embryonic chicks.
The origin of neural crest-derived ectomesenchymal condensations located subjacent to scleral papillae and the development of the more deeply situated scleral ossicles were investigated in scleral tissues explanted from the eyes of chick embryos at Hamburger & Hamilton (1952) stages 30-38 (6 1/2-12 days of incubation). Explants were pulse labelled with [3H]thymidine for 4h in vitro. Nuclear cou...
متن کاملEffect of Adenosine Agonists on the Proliferation and Differentiation of Chick Embryo Fibroblasts in Three Dimensional Reconstituted Tissue Constructs
Previous studies indicate that organ fibroblasts play an important role in wound healing, collagen production, remodeling processes and pathogenesis of progressive heart, lung, renal and hepatic fibrotic diseases. Several studies suggest a possible inhibitory role for adenosine in the regulation of fibroblast proliferation. The effect of adenosine A2 agonists on proliferation and differentiatio...
متن کاملViability and proliferation of epithelia and the initiation of osteogenesis within mandibular ectomesenchyme in the embryonic chick.
Ectomesenchyme, a derivative of the embryonic neural crest, forms the membrane bones of the mandibular skeleton, but will only do so after undergoing an inductive interaction with mandibular epithelium. Previously, non-mandibular epithelia have been shown to act as effective substitutes for the mandibular epithelium in this interaction. The role of epithelial viability was examined by enzymatic...
متن کاملCyclosporine Effects on Chick Limb Bud Mesenchyme and DNA Content
Background: Cyclosporine A (CsA) is a powerful immunosuppressive agent, which is used for the prevention of allograft rejection and for the treatment of autoimmune diseases. Many transplant recipients must take this medicine for the rest of their lives. Females in reproductive age group on prolonged CsA therapy have legitimate concerns about drug effects on pregnancy. Objective: To explore Cs...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of embryology and experimental morphology
دوره 88 شماره
صفحات -
تاریخ انتشار 1985