Arun M. Chilke
Labeo rohita is one of the Indian major carps present in all the freshwater ecosystems of India and is an economically important fish. Though primordial germ cells (PGCs) are biologically important as founders of germ cell lineage, no work has been carried out on PGCs of any of the Indian major carp. Therefore, the present work was undertaken to investigate the localization and migration of PGCs in L. rohita. PGCs are studied by collecting different stages of L. rohita by employing simple Hematoxylene-Eosine (HE) staining technique and were identified on the basis of their characteristic shape and size. Morphologically, they were elliptical as well as oval to spherical with clear cytoplasm. 24hrs (5mm) after hatching (ah), PGCs were identified and by 50mm stage of development, they were located on the gonadal ridge. These cells were bigger than the somatic or cyst cells which were present in their vicinity. Migrating germ cells were generally elliptical in shape and produced cytoplasmic extensions called fillopodia which help them in migration and adhesion. PGCs seem to have originated from the gut endoderm and started descending along the wall of intestine. From 24 hrs onwards, pronephric ducts are pushed upwards due to subsequent development of air sacs between the kidney and alimentary canal. Gonads were seen suspended in the coelomic cavity from 8 mm stage onwards from the dorsal body wall by a mesentery. Oogenic development was observed in 50 mm stage under light microscope in some specimens.
