Zusammenfassung
The development of the mullerian duct was studied in a total of 85 specimens of Acipenser ruthenus and Acipenser baeri in the period from 7 days after hatching through 5 years of age. Normal histology on serial sections, transmission and scanning electron microscopy and bromodeoxyuridine immunohistochemistry were applied. In Acipenser, the primary set of opisthonephric nephrons possess short ...
Zusammenfassung
The development of the mullerian duct was studied in a total of 85 specimens of Acipenser ruthenus and Acipenser baeri in the period from 7 days after hatching through 5 years of age. Normal histology on serial sections, transmission and scanning electron microscopy and bromodeoxyuridine immunohistochemistry were applied. In Acipenser, the primary set of opisthonephric nephrons possess short nephrostomial tubules with well-developed nephrostomes. Proliferating cells from the lateral side of the slightly protruding nephrostomial lips spread out over the ceolomic surface, replace here the flat mesothelium of lateral plate origin and establish the infundibular field, consisting of cuboidal or columnar cells. At about 28 days after hatching, the primordium of the mullerian infundibulum becomes visible in the form of a pocket-like invagination within the infundibular field. This invagination is found coexisting with and located laterally to the line of intact nephrostomes. The mullerian infundibulum, therefore, does not represent the homologon of a nephrostome itself, but must be regarded as a separate and secondary structure. The mullerian duct proper has its origin in cells from the bottom of the infundibular pocket. These cells grow as a tubule with a solid tip in the caudal direction, paralleling the wolffian duct, but without a contribution of cells from the latter. In Acipenser, a mullerian duct is present also in the adult male. In males as in females, the caudal extremity of the mullerian duct generally divides into two to three smaller terminals which end in the wolffian duct at different levels, but always cranial to the urogenital sinus. In most indifferent animals and in all males of this study, the tips of the mullerian terminals are closed and covered by a thin layer of wolffian epithelium. In adult females, the mullerian ducts end with open terminals. In both sexes, the adult mullerian duct is lined by a pseudostratified columnar epithelium, consisting of ciliated, non-ciliated and basal free cells.
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