Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Testes: Gross Anatomy01:19

Testes: Gross Anatomy

The testes, also known as testicles, are the male gonads. They are housed within the scrotum, a sac-like structure located beneath the penis. The scrotum's primary role is to regulate the temperature of the testes, which is crucial for sperm production.
Each testis is surrounded by the tunica albuginea, a dense connective tissue layer that provides structural support and protection. This layer is covered by an outer serous membrane called the tunica vaginalis, which helps reduce friction...
Testes: Histology01:27

Testes: Histology

A tough, fibrous membrane, the tunica albuginea, covers the testes, extending inward to form fibrous partitions or septa, dividing them into internal compartments called lobules. Each lobule has 1 to 3 tightly coiled seminiferous tubules where sperm production occurs. These tubules merge into a tubular network at the back of the testis, known as the rete testis. It connects to 15 to 20 efferent ductules, leading to the epididymis.
The spermatogenic cells, responsible for producing sperm, are...
The Y Chromosome Determines Maleness02:19

The Y Chromosome Determines Maleness

The Y chromosome is a sex chromosome found in several vertebrates and mammals, including humans. In addition to 22 pairs of autosomes, the human males have one X chromosome and one Y chromosome. In these organisms, the presence or absence of the Y chromosome determines the development of male traits.
Evolution
Around 300 million years ago, the two sex chromosomes diverged from two identical autosomal chromosomes. Over time, the Y chromosome has lost most of its genes, shrinking in size. Today,...
Heritability01:06

Heritability

Heritability is a statistical concept that measures the degree to which genetic differences among individuals contribute to trait variations within a population. It is a fundamental idea in genetics, often prone to misinterpretation. Heritability is expressed as a percentage, reflecting the proportion of variation in a specific trait across a population that can be linked to genetic differences. However, it's important to understand that heritability does not determine how "genetic" a trait is,...
The Ratio of X Chromosome to Autosomes02:45

The Ratio of X Chromosome to Autosomes

In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.  
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Accessory Ducts of the Male Reproductive System01:25

Accessory Ducts of the Male Reproductive System

The male reproductive system is a complex network of organs and tissues that work together to produce and transport sperm. The epididymis, vasa deferens, ejaculatory ducts, and urethra are the accessory ducts involved in sperm maturation and transportation. These ducts play a critical role in the production and transportation of sperm from the testes to the urethra, where it is then released during ejaculation.
The epididymis is a small, comma-shaped organ located at the back of each testicle.

You might also read

Related Articles

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

Sort by
Same author

Heritability of compulsive Internet use in adolescents.

Addiction biology·2015
Same author

CNV Concordance in 1,097 MZ Twin Pairs.

Twin research and human genetics : the official journal of the International Society for Twin Studies·2015
Same author

A twin-sibling study on early growth and hormone levels in adolescents.

Behavior genetics·2015
Same author

No evidence for genome-wide interactions on plasma fibrinogen by smoking, alcohol consumption and body mass index: results from meta-analyses of 80,607 subjects.

PloS one·2015
Same author

Genetic and environmental contributions to stability in adult obsessive compulsive behavior.

Twin research and human genetics : the official journal of the International Society for Twin Studies·2014
Same author

Stratification by smoking status reveals an association of CHRNA5-A3-B4 genotype with body mass index in never smokers.

PLoS genetics·2014

Related Experiment Video

Updated: Jun 21, 2026

Germ Cell Transplantation and Testis Tissue Xenografting in Mice
10:41

Germ Cell Transplantation and Testis Tissue Xenografting in Mice

Published on: February 6, 2012

Heritability of testis size.

G Frederiek Estourgie-van Burk1, Meike Bartels, Henriette A Delemarre-van de Waal

  • 1Department of Pediatrics, VU University Medical Center, Amsterdam, the Netherlands. f.estourgie@vumc.nl

Twin Research and Human Genetics : the Official Journal of the International Society for Twin Studies
|August 6, 2009
PubMed
Summary

Genetic and environmental factors influence male testis size. While heritability is estimated at 59%, shared environment also plays a significant role in testicular development.

More Related Videos

Assessing Differences in Sperm Competitive Ability in Drosophila
09:34

Assessing Differences in Sperm Competitive Ability in Drosophila

Published on: August 22, 2013

Teratoma Generation in the Testis Capsule
05:24

Teratoma Generation in the Testis Capsule

Published on: November 7, 2011

Related Experiment Videos

Last Updated: Jun 21, 2026

Germ Cell Transplantation and Testis Tissue Xenografting in Mice
10:41

Germ Cell Transplantation and Testis Tissue Xenografting in Mice

Published on: February 6, 2012

Assessing Differences in Sperm Competitive Ability in Drosophila
09:34

Assessing Differences in Sperm Competitive Ability in Drosophila

Published on: August 22, 2013

Teratoma Generation in the Testis Capsule
05:24

Teratoma Generation in the Testis Capsule

Published on: November 7, 2011

Area of Science:

  • Human genetics
  • Reproductive biology
  • Developmental biology

Background:

  • Testis size is a key indicator of male pubertal development.
  • Limited research exists on the genetic and environmental influences on human testis size variation.
  • Understanding these factors is crucial for assessing normal and abnormal pubertal progression.

Purpose of the Study:

  • To estimate the heritability of human testicular size.
  • To investigate the contributions of genetic and environmental factors to variations in testis size.
  • To explore potential differences in testis volume between monozygotic and dizygotic twins.

Main Methods:

  • A twin study design was employed, including monozygotic twins, dizygotic twins, and their non-twin brothers.
  • Participants (N=165 from 95 families) were approximately 18 years old and at Tanner stage 4 or higher.
  • Statistical models were used to estimate heritability and the influence of shared environment.

Main Results:

  • Significant familial resemblance in testis size was observed, with higher correlations in monozygotic twins (0.59) than dizygotic twins/siblings (0.34).
  • Heritability for testis size was estimated at 59%, though a model attributing resemblance solely to shared environment performed nearly as well.
  • Dizygotic twins and their siblings exhibited a larger mean testis volume compared to monozygotic twins and their siblings.

Conclusions:

  • Both genetic and environmental factors contribute to human testis size variation.
  • The substantial influence of shared environment suggests familial and lifestyle factors are important.
  • The observed larger testis volume in dizygotic twins warrants further investigation into twinning mechanisms.