Related Experiment Video

Updated: Jun 16, 2026

In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle
09:30

In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle

Published on: July 8, 2020

Consequences of nitric oxide synthase inhibition during bovine oocyte maturation on meiosis and embryo development

K R L Schwarz1, P R L Pires, T H C de Bem

  • 1Departamento de Ciências Básicas, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga-SP, Brazil.

Reproduction in Domestic Animals = Zuchthygiene
|February 9, 2010
PubMed

Insights

Nitric oxide synthase (NOS) inhibition in bovine oocytes reduced maturation rates but improved embryo quality. NOS deficiency during maturation may increase embryo apoptosis, highlighting NO's role in meiosis and embryo development.

Area of Science:

  • Reproductive Biology
  • Developmental Biology
  • Biochemistry

Background:

  • Nitric oxide (NO) plays a crucial role in various physiological processes, including reproduction.
  • Understanding the role of nitric oxide synthase (NOS) in bovine oocyte maturation is essential for improving in vitro fertilization (IVF) outcomes.

Purpose of the Study:

  • To investigate the impact of nitric oxide synthase (NOS) inhibition on bovine oocyte maturation and subsequent embryo development and quality.
  • To determine the specific effects of NOS inhibition during different stages of oocyte culture (pre-maturation and maturation).

Main Methods:

  • Bovine oocytes were matured in vitro with varying concentrations of N(w)-L-nitro-arginine methyl-ester (L-NAME), a NOS inhibitor.
  • Metaphase II (MII) rates, cleavage, blastocyst development, and embryo quality (total cell number, apoptosis via TUNEL assay) were assessed.
  • L-NAME was applied during pre-maturation and/or maturation stages to evaluate stage-specific effects.

Main Results:

  • L-NAME treatment significantly decreased MII rates compared to controls.
  • While cleavage and Day 7 blastocyst rates were unaffected, Day 8 blastocyst apoptosis (TUNEL-positive cells) increased with L-NAME treatment.
  • NOS inhibition during pre-maturation and/or maturation led to increased total cell numbers in Day 9 hatched blastocysts, but also elevated apoptosis when inhibition occurred solely during maturation.

Conclusions:

  • Nitric oxide synthase is involved in the meiotic progression of bovine oocytes to MII.
  • NO deficiency during oocyte maturation can increase apoptosis in in vitro-produced embryos.
  • Inhibiting NOS during pre-maturation and/or maturation impacts overall embryo quality, suggesting a complex role for NO in bovine reproduction.

More Related Videos

Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes12:11

Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes

Published on: May 11, 2017

Proteolytically Degraded Alginate Hydrogels and Hydrophobic Microbioreactors for Porcine Oocyte Encapsulation07:45

Proteolytically Degraded Alginate Hydrogels and Hydrophobic Microbioreactors for Porcine Oocyte Encapsulation

Published on: July 30, 2020

Related Concept Videos

Meiosis I03:09

Meiosis I

Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of meiosis, where the genetic recombination of homologous chromosomes and the reduction of the ploidy level by half occurs.
Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...
Oogenesis02:07

Oogenesis

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...
Oogenesis01:22

Oogenesis

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...
Nitric Oxide Signaling Pathway01:28

Nitric Oxide Signaling Pathway

Nitric oxide (NO), an inorganic gas, acts as a potent second messenger in most animal and plant tissues. NO diffuses out of the cells that produce it and enters the neighboring cells to generate a downstream response. NO synthase (NOS) catalyzes NO production by the deamination of the amino acid arginine. There are three isoforms of NOS. Endothelial cells have endothelial NOS (eNOS), nerve and muscle cells have neuronal NOS (nNOS), and macrophages produce inducible NOS (iNOS) upon exposure to...
Meiosis II01:57

Meiosis 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...
Meiosis II02:02

Meiosis 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.
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...