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Oogenesis in teleosts: how eggs are formed
Esther Lubzens1, Graham Young, Julien Bobe
1Department of Marine Biology, Israel Oceanographic and Limnological Research, 81080 Haifa, Israel. esther@ocean.org.il
General and Comparative Endocrinology
|June 10, 2009
Summary
Understanding teleost fish oocyte development is crucial for aquaculture. This review highlights advances in oocyte differentiation, maturation, and ovulation, focusing on hormonal regulation and egg formation processes.
Area of Science:
- Reproductive Biology
- Aquaculture Science
- Endocrinology
Background:
- Aquaculture aims to produce numerous viable eggs with high survival rates.
- Significant progress has been made in improving egg production efficiency and progeny viability.
- Gaps persist in understanding the intricate processes of oogenesis in teleosts, from germ cell development to ovulation.
Purpose of the Study:
- To review recent advancements in teleost fish oocyte differentiation, maturation, and ovulation.
- To elucidate the complex hormonal cross-talk regulating oocyte development.
- To highlight new insights into egg formation, including atresia and the roles of various regulatory factors.
Main Methods:
- Literature review of recent studies on teleost oogenesis.
- Analysis of research on primordial germ cells, yolk precursors, and vitamin deposition.
- Examination of studies on egg envelope structure, oocyte maturation, and hormonal regulation.
Main Results:
- Oogenesis involves complex processes including germ cell development, yolk deposition, and maturation.
- Pituitary gonadotropins (LH and FSH) and sex steroids are key regulators, alongside paracrine and autocrine factors.
- Complex hormonal interactions between the oocyte and follicle layers are essential for producing fertilizable eggs.
Conclusions:
- Recent research reveals the complexity of teleost oocyte development and maturation.
- Understanding hormonal regulation and local factors is key to improving aquaculture egg production.
- Further research into oocyte differentiation, maturation, ovulation, and atresia is vital for the industry.
Related Concept Videos
01:22Oogenesis
Oogenesis, the process of developing egg cells (female gametes), occurs within the ovaries and is fundamental to female fertility. This sequence begins during fetal development when diploid oogonia in the developing ovaries undergo mitotic divisions to produce primary oocytes. By birth, these primary oocytes enter prophase I of meiosis but become arrested in this stage, remaining suspended until puberty.
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is known...
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is known...
02:07Oogenesis
In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from the equivalent procedure of spermatogenesis in males. First, meiotic divisions during oogenesis are asymmetric, meaning that a large oocyte (containing most of the cytoplasm) and minor polar body are produced as a result of meiosis I, and again following meiosis II. Since only oocytes will go on to form embryos if fertilized, this unequal...
01:20Folliculogenesis
Folliculogenesis is the development of ovarian follicles, the specialized structures within the ovarian cortex where oogenesis, or egg development, occurs. This process is essential for female reproductive health and begins during fetal development when primordial follicles are formed. Each primordial follicle comprises a primary oocyte in the center, surrounded by a single layer of squamous pre-granulosa cells. These follicles remain dormant in late prophase I of meiosis until triggered by...
02:02Meiosis II
Meiosis II entails cell division and segregation of the sister chromatids, resulting in the production of four unique haploid gametes. The steps for meiosis II are similar to mitosis, except that meiosis II occurs in haploid cells, whereas mitosis occurs in diploid cells.
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01:57Meiosis II
Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 chromosomes—one from each homologous initial pair. Importantly, each chromosome in these cells is composed of two joined copies, and when these cells enter meiosis II, the goal is to separate such sister chromatids using the same microtubule-based network employed in other division processes. The result of meiosis II is two haploid cells, each containing...
01:36What is Meiosis?
Meiosis is the process by which diploid cells divide to produce haploid daughter cells. In humans, each diploid cell contains 46 chromosomes, half from the mother and half from the father. Following meiosis, the resulting haploid eggs or sperm only contain 23 chromosomes; however, each of these chromosomes contains a unique combination of parental information that results from the meiotic process of crossing over.