Morphological and immunohistochemical study of testicular capsule and peritubular tissue of emu (Dromaius novaehollandiae) and ostrich (Struthio camelus)

Abstract

The testicular capsule and peritubular boundary tissue of the emu and ostrich, as typical representatives of ratite birds, were studied in sexually mature and active birds. The testicular capsule was much thicker (578.1±73.4 m for the free surface of the ostrich testis, and 176.2±57.5 mfor the emu) than those of members of the Galloanserae. The cellular composition of both testicular capsule and peritubular tissue was similar generally to that of members of the previously studied Galloanserae and of mammals. The tunica albuginea of the testicular capsule mainly comprised smooth-musclelike or myoid cells mostly running in one direction and occurring in one main mass. Unlike the Galloanserae, the tunica albuginea contained more collagen fibres than smooth muscle cells, especially in the ostrich. Peritubular tissue was similarly composed of smooth-muscle-like cells distributed in several layers. Actin microfilaments and desmin and vimentin intermediate filaments were variably immunoexpressed in these two tissue types in both birds, with a clear dichotomy in the peritubular tissue. Thus, taken together with studies of some members of the Galloanserae, avian testes clearly contain a morphological mechanism that is represented partly by the smooth muscle cells of the testicular capsule and peritubular tissue for transporting the testicular fluid, which is usually copious in birds, and its cellular content from the testis into the excurrent duct system; thismechanism is similar to that found in mammals.

The cytoskeletal proteins in the contractile tissues of the testis and its excurrent ducts of the passerine bird, Masked Weaver (Ploceus velatus)

“…The present report complements previous morphological and immunohistochemical studies in other Orders and Families of birds, Galloanserae and Ratitae (Aire and Ozegbe, 2007;Maretta and Marettova, 2004;Ozegbe et al, 2008Ozegbe et al, , 2010van Nassauw et al, 1993), with regard to contractile elements in the testis and its excurrent ducts. There is a great deal of variability in the immunoexpression of different microfilament and intermediate filament systems between this passerine bird and other birds studied (Aire and Ozegbe, 2007;Maretta and Marettova, 2004;Ozegbe et al, 2008Ozegbe et al, , 2010van Nassauw et al, 1993), and between birds and mammals, as there are between mammals (Dinges et al, 1991;Kasper and Stosiek, 1989;Palacios et al, 1991;Wakui et al, 1994).…”

“…While the smooth muscle cells in the testicular capsule were generally regular and nonbranching, as in the Galloanserae, those of the ratites branched rather elaborately, with sheets of cytoplasm meandering between and enclosing bundles of collagen fibres. The ultrastructure of the smooth muscle cells is similar in all Orders of birds studied so far (Aire and Ozegbe, 2007;Ozegbe et al, 2008;Rothwell and Tingari, 1973). There is no remarkable variability in ultrastructure of the smooth muscle cell in either the testicular capsule, peritubular or periductal tissues.…”

“…The testicular capsule of the Masked weaver, as has been described for members of the Galloanserae, is thin but relatively thick in the Ratitae (Aire and Ozegbe, 2007;Ozegbe et al, 2008). While the smooth muscle cells in the testicular capsule were generally regular and nonbranching, as in the Galloanserae, those of the ratites branched rather elaborately, with sheets of cytoplasm meandering between and enclosing bundles of collagen fibres.…”

“…There is no remarkable variability in ultrastructure of the smooth muscle cell in either the testicular capsule, peritubular or periductal tissues. As in mammals (Lesson and Forman 1981;Langford and Heller 1973;Holstein and Weiss 1967;Banks et al, 2006) and other birds (Aire and Ozegbe, 2007;Ozegbe et al, 2008), the testicular capsule, peritubular and periductal tissues contain smooth muscle cells that are most probably responsible for transporting testicular fluid from the testis into and through its excurrent ducts.…”

“…actin, cytokeratins, desmin and vimentin) in both epithelial and periductal tissue smooth muscle cells of the excurrent ducts of the testis in mammals (Achstätter et al, 1985;Ramaekers et al, 1985;Dinges, et al, 1991;Kasper and Stosiek, 1989;Palacios et al, 1993;Wakui et al, 1994). There are only a few reports on the contractile proteins in the testis and its complex excurrent duct system in birds (Aire, 1997;Aire and Ozegbe, 2007;Ozegbe et al, 2008Ozegbe et al, , 2010Maretta and Marettova, 2004;Rothwell and Tingari, 1973;van Nassauw et al, 1993). Actin microfilaments (MF) as well as desmin, cytokeratin and vimentin intermediate filaments (IFs) have been immunodemonstrated in both the testis and its excurrent ducts in members of the Galloanserae and Ratitiae (Maretta and Marettova, 2004, Aire and Ozegbe, 2007, 2010.…”