Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Case Studies

Case Studies

There are many research methods available to psychologists in their efforts to understand, describe, and explain behavior and the cognitive and biological processes that underlie it.

Crossing Over

Crossing Over

Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...

Crossing Over

Crossing Over

Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...

Sutures of the Skull

Sutures of the Skull

The human skull is composed of several bones that come together to protect the brain and support the structures of the face. The junctions where these bones meet are called sutures.
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...

Nondisjunction

Nondisjunction

During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.

Nondisjunction

Nondisjunction

During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Motorist's Disorientation Syndrome-A Narrative Review.

Journal of functional morphology and kinesiology·2026

Same author

Investigation of Heart Rate Variability Indices in Motion Sickness.

Sensors (Basel, Switzerland)·2026

Same author

Sex and age differences of postural control in community-dwelling older adults.

Frontiers in human neuroscience·2026

Same author

Obstructive sleep apnea in children: prevalence and association with overweight and obesity.

Frontiers in sleep·2026

Same author

Exploring Dynamic Alpha Band Connectivity in Parkinson's Disease: A Novel Approach to Postural Control Assessment Using the BioVRSea Paradigm.

Brain topography·2026

Same author

Impact of Balance and Dizziness Problems on Falls in Older Adults: The Longitudinal AGES-Reykjavik Study.

Laryngoscope investigative otolaryngology·2025

Search research articles

Related Experiment Video

Updated: Jun 17, 2026

Model Surgical Training: Skills Acquisition in Fetoscopic Laser Photocoagulation of Monochorionic Diamniotic Twin Placenta Using Realistic Simulators

Model Surgical Training: Skills Acquisition in Fetoscopic Laser Photocoagulation of Monochorionic Diamniotic Twin Placenta Using Realistic Simulators

Published on: March 21, 2018

[Conjoined twins. Historical review].

Valgardur Egilsson, Hannes Petersen

|December 10, 2009

Summary

This study reviews Icelandic historical logs, identifying five cases of conjoined twinning. It proposes a new view of the pathogenesis of this rare newborn malformation.

Area of Science:

Embryology and teratology
Medical history
Perinatal medicine

Context:

Conjoined twinning is a rare congenital anomaly with significant implications for newborn health.
Historical medical records offer unique insights into the prevalence and understanding of congenital malformations.
Icelandic historical logs provide a specific, underutilized resource for studying rare medical phenomena.

Purpose:

To investigate the historical documentation of conjoined twinning in Iceland.
To analyze the embryologic background and propose novel insights into the pathogenesis of conjoined twinning.
To contribute to the understanding of rare congenital malformations through historical data.

Summary:

The study examines Icelandic historical logs, identifying four definite and one uncertain case of conjoined twinning.

More Related Videos

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas

Published on: September 5, 2011

Accurate and Simple Evaluation of Vascular Anastomoses in Monochorionic Placenta using Colored Dye

Accurate and Simple Evaluation of Vascular Anastomoses in Monochorionic Placenta using Colored Dye

Published on: September 5, 2011

Related Experiment Videos

Last Updated: Jun 17, 2026

Model Surgical Training: Skills Acquisition in Fetoscopic Laser Photocoagulation of Monochorionic Diamniotic Twin Placenta Using Realistic Simulators

Model Surgical Training: Skills Acquisition in Fetoscopic Laser Photocoagulation of Monochorionic Diamniotic Twin Placenta Using Realistic Simulators

Published on: March 21, 2018

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas

Published on: September 5, 2011

Accurate and Simple Evaluation of Vascular Anastomoses in Monochorionic Placenta using Colored Dye

Accurate and Simple Evaluation of Vascular Anastomoses in Monochorionic Placenta using Colored Dye

Published on: September 5, 2011

It provides an overview of the embryologic origins of conjoined twinning.

New perspectives on the pathogenesis of conjoined twinning are presented based on historical and embryological data.

Impact:

Enhances understanding of the historical prevalence of conjoined twinning in a specific population.
Offers a novel theoretical framework for the pathogenesis of conjoined twinning.
Highlights the value of historical archives in medical research, particularly for rare conditions.