Learn More
Spermiogenesis in Thysaniezia ovilla begins with the appearance of a differentiation zone equipped with peripheral microtubules, surrounded by arched membranes and containing two parallel centrioles surrounded by electron dense granular material. One of the centrioles aborts, the other gives rise to a flagellum which quickly grows in the cytoplasmic(More)
Chondrichthyes possess an evolved type of spermatozoa. Their flagellar apparatus is characterized by the presence of flagellar roots which form the axis of the midpiece, and the existence of one or two lateral elements associated with the axoneme. Osteichthyes, mainly teleosteans, show a great diversity of spermatic forms. The primitive spermatozoon with a(More)
The Centrorhynchus milvus spermatozoon is a filiform cell. The free part of the flagellum measure 2 mu and is situated in front of the gamete. The centriole is no more visible but an axial tubule formation is found at the anterior extremity of the flagellum. This Polymorphidae spermatozoon shows a reversed anatomy like the one we described for the first(More)
Diplozoon is known to display an exceptional biology of reproduction: the hermaphroditic adults are permanently fused together and their genital ducts communicate. In contrast to all other polyopisthocotylean monogeneans in which the spermatozoa show an homogeneous biflagellate structure, the spermatozoon of Diplozoon is aflagellate. It is filiform, and(More)
This study examines the evolution of mitochondria in the follicular cells during the development of the ovarian follicle in the teleostean fish Epiplatys spilargyreus. The mitochondria are few in number until the end of previtellogenesis; their matrix is dense, and their cristae are well developed. They proliferate during vitellogenesis and then are(More)
During the long starvation period (November to June) of the lizard (Varanus exanthematicus), pancreatic B cells undergo profound modification. The degeneration of beta granules observed in electron microscopy appears correlated with the diminution of the immunoreactive insulin-like content of the pancreas. The analogy between the phenomena observed here and(More)
In Megalocotyle the zones of differentiation (ZD) are short and incomplete; there is no median cytoplasmic process or free flagella. Some peripheral microtubules are present in early ZD, but they disappear. Each nucleus of the common cytoplasmic mass inserts one extremity into a ZD. The mitochondria fuse around this extremity and form a beadlike perforated(More)
The early spermatid possesses a round nucleus and a diplosome which is close to the cellular membrane and with which paracentriolar formations are associated; a sole mitochondrion is located between the diplosome and the nucleus. During the spermatid evolution, the nucleus is laterally elongated, its main axis being perpendicular to the flagellar axis; the(More)