The zebrafish prospero homolog prox1 is required for mechanosensory hair cell differentiation and functionality in the lateral line

Background  

The lateral line system in zebrafish is composed of a series of organs called neuromasts, which are distributed over the body surface. Neuromasts contain clusters of hair cells, surrounded by accessory cells.     

The Paraspermatic Cell (Atypical Spermatozoon) of Prosobranchia: A Comparative Ultrastructural Study

Melone, G., Lora Lamia Donin, C., Cotelli, F. 1980. The paraspermatic cell (atypical spermatozoon) of Prosobranchia: a comparative ultrastructural study. (Institute of Zoology, University of Milan, Milano, Italy.) — Acta zool. (Stockh.) 61(4): 191–201. The ultrastructure of the paraspermatic cells (atypical spermatozoa) in the male genital tracts of nine species of marine Prosobranchia is described. These cells derive from the same germinal line as the typical spermatozoa, and seem to be homogeneous in their general constitution. In all nine species the paraspermatic cells are characterized by the presence of granules. Axonemes are present in all except one species. Various kinds of paraspermatic cell movements are described; three of the nine species have not yet demonstrated any motility. The significance and the function of paraspermatic cells are discussed.     

Immunocytochemical localization of actin in the sperm head of Talpa europaea (Insectivora)

Actin in the sperm head of Talpa europaea was observed by immunofluorescence and immunoelectron microscopy. The indirect immunofluorescence technique, using both anti-actin and DNase anti-DNase methods, showed a shining fluorescent band around the sperm head in some spermatozoa, whereas in others the fluorescence was found in the postacrosomal region. Since no labeling was detected in sperms treated with NBD-phallacidin, it is likely that mature mole sperms contain G-actin but not F-actin. The results of electron microscopy indicated the deposition of the anti-actin antibodies in two places in mole spermatozoa: the postacrosomal region and the nuclear segment of the acrosome. In the first case, the actin was localized in the space between the outer surface of the postacrosomal sheath and the plasma membrane; in the second one, the actin was localized in the space between the outer acrosomal membrane and the plasma membrane. The significance of the presence of actin and its role(s) during fertilization are discussed.