Original and formation of the ovary with particular reference to the development of the oocytes in Eucyclops agilis (Koch)
Original and formation of the ovary with particular reference to the development of the oocytes in Eucyclops agilis (Koch)
The life cycle of Eucyclops agilis was investigated in relation to a study of germ and oogonial cell lineage in the larval stages and oogenesis in the adult. The results of the life cycle study showed that under conditions of laboratory culture there were six naupliar stages not five as previously reported, and five copepodite stages before the emergence of the adult. The development of the germ and oogonial lineage appears to be clearly related to the progressive development of the larval stages. The lineage starts in the nauplius stage with two primordial germ cells and there is a progressive increase in the number of germ cells through copepodite stages one, two and three. By copepodite stage four sex determination has taken place and oogonia are detected in the ovary. Oogenesis starts at copepodite five stage when the initial stages in the differentiation of the oocyte appear. Studies of the adult ovary based primarily on electron microscope observations show the ovary as a bilobed structure surrounded by a single layer of epithelial cells. Three zones are distinguishable, a germinative zone containing oogonia, a synaptic zone containing previtellogenic and premeiotic oocytes and a growth zone containing oocytes undergoing primary vitellogenesis. Primary vitellogenesis is associated with extensive development of the endoplasmic reticulum and the production of intracistemal granules which fuse to form platelets of endogenous yolk. Secondary vitellogenesis takes place in oocytes located in the oviduct. Two types of exogenous yolk platelets are formed involving micropinocytotic accumulation of material from the haemolymph.
University of Southampton
1988
Comber, David Henry
(1988)
Original and formation of the ovary with particular reference to the development of the oocytes in Eucyclops agilis (Koch).
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The life cycle of Eucyclops agilis was investigated in relation to a study of germ and oogonial cell lineage in the larval stages and oogenesis in the adult. The results of the life cycle study showed that under conditions of laboratory culture there were six naupliar stages not five as previously reported, and five copepodite stages before the emergence of the adult. The development of the germ and oogonial lineage appears to be clearly related to the progressive development of the larval stages. The lineage starts in the nauplius stage with two primordial germ cells and there is a progressive increase in the number of germ cells through copepodite stages one, two and three. By copepodite stage four sex determination has taken place and oogonia are detected in the ovary. Oogenesis starts at copepodite five stage when the initial stages in the differentiation of the oocyte appear. Studies of the adult ovary based primarily on electron microscope observations show the ovary as a bilobed structure surrounded by a single layer of epithelial cells. Three zones are distinguishable, a germinative zone containing oogonia, a synaptic zone containing previtellogenic and premeiotic oocytes and a growth zone containing oocytes undergoing primary vitellogenesis. Primary vitellogenesis is associated with extensive development of the endoplasmic reticulum and the production of intracistemal granules which fuse to form platelets of endogenous yolk. Secondary vitellogenesis takes place in oocytes located in the oviduct. Two types of exogenous yolk platelets are formed involving micropinocytotic accumulation of material from the haemolymph.
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Published date: 1988
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Local EPrints ID: 460502
URI: http://eprints.soton.ac.uk/id/eprint/460502
PURE UUID: 30d46e68-284f-4e24-9dfc-90ef59248ce2
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Date deposited: 04 Jul 2022 18:23
Last modified: 04 Jul 2022 18:23
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Author:
David Henry Comber
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