OVARIAN CHANGES DURING THE REPRODUCTIVE CYCLE

MANES, MARIO; NORIEGA, TERESA; CASAL CAMPOS, FERNANDO; APICHELA, SILVANA A.

CUADERNOS DE HERPETOLOGíA

Asociación Herpetológica Argentina

Lugar: La Plata; Año: 2007 vol. 21 p. 17 - 25

0326-551X

The reproductive cycle of Tupinambis merianae females raised in a temperate environment consists of three gonadal phases: previtellogenic, vitellogenic and postovulatory or luteal phases. During the previtellogenic phase, which takes great part of the summer, autumn and winter, the ovaries are small, weigh less than 4 g, and contain only nonvitellogenic follicles, which develop slowly from germinal beds, until they are almost 5 mm diameter. Due to an asynchronous gonadal maturation in both sexes, matings occur when ovaries are still previtellogenic. Then comes a short and intense vitellogenesis, during which follicles grow steadily increasing around 6 times their diameter (close to 30 mm), while the total ovarian mass reaches almost 400 g. The process culminates between the 15th and 20th day, with a widespread ovulation and a subsequent oviposition. As a consequence, postovulatory ovaries appear reduced to 5 g approximately, with a surface almost entirely covered with follicular scars, which soon developed luteal bodies. Blockade of the ovarian cycle, with a massive previtellogenic follicular atresia, as a result of females isolation leads to conclude on the existence of sexual stimuli promoting vitellogenesis.