OOGENESIS AND THE OVARIAN CYCLE IN SALAMANDRA-SALAMANDRA-INFRAIMMACULATA MERTENS (AMPHIBIA, URODELA, SALAMANDRIDAE) IN FRINGE AREAS OF THE TAXONS DISTRIBUTION

Reproductive cycle and oogenesis were studied in specimens of Salamand ra salamandra infraimmaculata Mertens that inhabit fringe areas of the taxon's distribution in the Mediterranean region. Both ovarian mass a nd length are correlated significantly with body mass and length. Ovar ian length is also correlated with the number of oocytes. During the o ogenetic cycle six stages in oocyte development were recognized. Three occur during previtellogenesis: stage 1, in which oogonia divide and form cell nests; stage 2 in which oogonia differentiate into oocytes; and stage 3, in which the oocyte cytoplasm increases in volume. In the vitellogenic phase two additional stages, 4 and 5, were recognized: s tage 4, in which lipid accumulates in vacuoles in the periphery follow ed by the appearance of yolk platelets near the cytoplasmic margin; an d stage 5, in which oocyte volume increases rapidly due to increased n umber of yolk platelets until it reaches its maximal size. During post vitellogenesis one stage was recognized: stage 6, in which the beginni ng of maturation is characterized by movement of the nucleus toward th e animal pole. Oogenesis continues year-round. The first four stages w ere seen in all ovaries examined. The ovarian cycle is independent of season and reproductive stage apart from the number of mature, postvit ellogenic oocytes that increases following gestation toward the beginn ing of spring (March-April). (C) 1997 Wiley-Liss, Inc.