Pallial oviduct of Pomacea canaliculata (Gastropoda): ultrastructural studies of the parenchymal cellular types involved in the metabolism of perivitellins

CATALÁN, M.; DREON, M.S.; HERAS, H.; POLLERO, R.J.; FERNÁNDEZ,S.; WINIK,B.

CELL AND TISSUE RESEARCH

Año: 2006 vol. 324 p. 523 - 533

0302-766X

Seasonal variations of the parenchymal mass morphology and function of the albumen gland-capsule gland complex (AGC) and the cellular types involved in the synthesis and secretion of perivitellin fluid (PVF) components in Pomacea canaliculata were studied. The two major parenchymal cell types, albumen secretory cells (AS) and labyrinthic cells (LC) undergo seasonal variations through the annual reproductive cycle which has been divided into 3 periods. Both cellular types show maximal development and structural complexity at the reproductive period (spring and summer). AS cells have a well developed Golgi complex and rough endoplasmic reticulum. Its secretory granules show electron-dense particles of about 20 nm, probably galactogen. AS are the unique parenchymal cells involved in ovorubin and PV2 perivitellin synthesis and their secretory granules is the single storage site, as revealed by immunoelectronmicroscopy. The same secretory granules hold these two major perivitellins. AS also present calcium deposits that infiltrate the cytoplasmic matrix. LC luminal surfaces exhibit long cilia intermingled with scarce short microvilli. Basally, the plasma membrane shows deep irregular folds that extend through the cytoplasm up to the subapical region. Calcium deposits infiltrate cytoplasm and accumulate in the extracellular space of the basal labyrinth. Nerve terminals seem involved in the regulation of parenchymal cell secretion. At the post-reproductive period AS markedly change its aspect due to the release of most secretory granules into the acinar lumen. LC decrease in volume and number of cilia, their cytoplasmic folds are much thinner and extracellular spaces lack calcic particles. At the pre-reproductive period (winter) AS and LC recover and prepare for the following period.