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

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...
Testing a Claim about Population Proportion01:24

Testing a Claim about Population Proportion

A complete procedure for testing a claim about a population proportion is provided here.
There are two methods of testing a claim about a population proportion: (1) Using the sample proportion from the data where a binomial distribution is approximated to the normal distribution and (2) Using the binomial probabilities calculated from the data.
The first method uses normal distribution as an approximation to the binomial distribution. The requirements are as follows: sample size is large...
Hardy-Weinberg Principle01:49

Hardy-Weinberg Principle

Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the gene pool of the population. The gene pool of a population is the sum of every allele of all genes within that population and has some degree of variation. Genetic variation is typically expressed as a relative frequency, which is the percentage of the total population that has a given allele, genotype or phenotype.In the early 20th century,...
Dosage Compensation02:50

Dosage Compensation

In animals, gender is determined by the number and type of sex chromosome. For example, human females have two X chromosomes, and males have one X and one Y chromosome, whereas C.elegans with one X chromosome is a male, and the one with two X chromosomes is a hermaphrodite.
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with  distinct numbers of X chromosomes will have...
Natural Selection and Mating Preferences01:06

Natural Selection and Mating Preferences

The principle of natural selection posits that organisms better adapted to their environment are more likely to survive and reproduce. This principle is closely intertwined with mating preferences, a key aspect of sexual selection, which evolutionary psychologists believe is driven by instincts to propagate one's genes. Such instincts significantly influence mating behaviors and preferences between genders.
Females, due to their biological roles in conception, pregnancy, and nursing, inherently...
Chi-square Analysis02:46

Chi-square Analysis

The chi-square test is a statistical hypothesis test. It is used to check whether there is a significant difference between an expected value and an observed value. In the context of genetics, it enables us to either accept or reject a hypothesis, based on how much the observed values deviate from the expected values.
The chi-square test was developed by Pearson in 1990.
The first step of performing a Chi-square analysis is to establish a null hypothesis, which assumes that there is no real...

You might also read

Related Articles

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

Sort by
Same author

Biologically inspired digital histology for deep phenotyping of placental composition changes across major lesion types.

Placenta·2026
Same author

Biologically Inspired Digital Histology for Deep Phenotyping of Placental Composition Changes Across Major Lesion Types.

bioRxiv : the preprint server for biology·2026
Same author

Prenatal and early childhood exposure to phthalates and neurodevelopment in 42 months old children.

Neurotoxicology·2025
Same author

Intranasal oxytocin interacts with testosterone reactivity to modulate parochial altruism.

Communications psychology·2024
Same author

Mapping cell-to-tissue graphs across human placenta histology whole slide images using deep learning with HAPPY.

Nature communications·2024
Same author

Gradual dosing of ursodeoxycholic acid in mothers with intrahepatic cholestasis of pregnancy may improve composite neonatal outcome.

Annals of hepatology·2024

Related Experiment Video

Updated: Jun 26, 2026

Determining the Egg Fertilization Rate of Bemisia tabaci Using a Cytogenetic Technique
05:24

Determining the Egg Fertilization Rate of Bemisia tabaci Using a Cytogenetic Technique

Published on: April 1, 2019

Sex ratio is remarkably constant.

Eliana Ein-Mor1, David Mankuta, Drorith Hochner-Celnikier

  • 1Department of Obstetrics and Gynecology, Hadassah Hebrew University Medical Center, Jerusalem, Israel.

Fertility and Sterility
|January 23, 2009
PubMed
Summary
This summary is machine-generated.

This study found that the male-to-female sex ratio at birth remains constant and is not influenced by parental age or birth order. Gestation length was the only significant factor affecting the sex ratio.

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

Visually Sexing Loggerhead Shrike (Lanius Ludovicianus) Using Plumage Coloration and Pattern
04:10

Visually Sexing Loggerhead Shrike (Lanius Ludovicianus) Using Plumage Coloration and Pattern

Published on: March 8, 2020

Related Experiment Videos

Last Updated: Jun 26, 2026

Determining the Egg Fertilization Rate of Bemisia tabaci Using a Cytogenetic Technique
05:24

Determining the Egg Fertilization Rate of Bemisia tabaci Using a Cytogenetic Technique

Published on: April 1, 2019

Assessing Differences in Sperm Competitive Ability in Drosophila
09:34

Assessing Differences in Sperm Competitive Ability in Drosophila

Published on: August 22, 2013

Visually Sexing Loggerhead Shrike (Lanius Ludovicianus) Using Plumage Coloration and Pattern
04:10

Visually Sexing Loggerhead Shrike (Lanius Ludovicianus) Using Plumage Coloration and Pattern

Published on: March 8, 2020

Area of Science:

  • Reproductive biology
  • Human genetics
  • Demography

Background:

  • The sex ratio at birth is a fundamental demographic indicator.
  • Previous studies have explored potential associations between parental factors and offspring sex.
  • Hypotheses suggest parental age, gravidity, and parity may influence the male-to-female sex ratio.

Purpose of the Study:

  • To investigate the relationship between parental age, gravidity, and parity and the sex of offspring.
  • To determine if advancing parental age alters the male-to-female sex ratio at birth.

Main Methods:

  • A large retrospective cohort study analyzing 35,837 birth records.
  • Data collected from Hadassah Hebrew University Medical Center between June 2003 and December 2006.
  • Exclusion criteria included foreign inhabitants, missing data, and parturients over 50 years to control for egg donation.

Main Results:

  • The overall male-to-female sex ratio was 1.05.
  • No significant changes in the sex ratio were observed with increasing maternal or paternal age.
  • Gravidity and parity did not demonstrate an effect on the male-to-female sex ratio; gestation length was the sole significant factor.

Conclusions:

  • The sex ratio at birth exhibits remarkable consistency.
  • No correlation was identified between parental age or birth order and the neonatal sex ratio.
  • These findings suggest that factors other than parental age and birth order are primary determinants of offspring sex.