A description of the ovarian
development stages of penaeid shrimps from the coast of Pakistan
Z. Ayub, M. Ahmed-2002
Aquaculture
Research, 33(10):
767-776
Abstract:
In this study, four species of penaeid shrimp from Pakistan's
inshore waters were studied. These were Penaeus penicillatus
(Alcock), Penaeus merguiensis (de Man), Metapenaeus affinis
(Milne Edwards) and Parapenaeopsis stylifera (Milne Edwards).
During maturation, shrimp ovaries pass through a series of colour changes.
The various colours observed in the ovaries of the four species of penaeid
shrimps were translucent, white, cream, yellow, green-yellow, green-white,
light green and dark green. The different type of oocytes observed in
histological sections of the penaeid ovaries are as follows: chromatin
nucleolar oocytes, perinucleolar oocytes, yolkless oocytes, yolky oocytes
and oocytes with cortical bodies. The ovarian developmental stages
recognized in these shrimps are: undeveloped, developing, nearly ripe, fully
ripe, resorbing and resorbing/ developing. The ovarian developmental stages
were similar in all the four species with the exception of the fully ripe
stage. In the fully ripe stage of P. penicillatus and P.
merguiensis, the cortical bodies were present at the periphery in two
shapes; spherical as well as rod-like. On the other hand, in the fully ripe
stage of M. affinis and P. stylifera, the cortical bodies were
present only at the periphery and were only spherical. A relationship
between colour of ovaries and histological stages of ovarian development was
established. A female shrimp with a dark-green ovary is an indication
of the ready- to-spawn condition. In P. merguiensis and Penaeus
penicillatus, respectively, 100% and 88.1% females with dark-green
ovaries had oocytes with cortical bodies, whereas in M. affinis and P.
stylifera, respectively, 50% and 28.6% females with dark-green ovaries
had oocytes with cortical bodies.
(Centre of Excellence in Marine Biology, University of Karachi,
Karachi-75270, Pakistan. E-mail: zarrien@sat.net.pk)