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

Spermatogenesis01:41

Spermatogenesis

124.7K
Spermatogenesis is the process by which haploid sperm cells are produced in the male testes. It starts with stem cells located close to the outer rim of seminiferous tubules. These spermatogonial stem cells divide asymmetrically to give rise to additional stem cells (meaning that these structures “self-renew”), as well as sperm progenitors, called spermatocytes. Importantly, this method of asymmetric mitotic division maintains a population of spermatogonial stem cells in the male...
124.7K
Spermatogenesis01:22

Spermatogenesis

10.9K
Spermatogenesis is a complex process that involves the development of sperm cells from undifferentiated stem cells in the seminiferous tubules of the testes. The process is essential for the production of mature and functional sperm cells that are capable of fertilizing an egg.
The process of spermatogenesis can be divided into mitosis, meiosis, and spermiogenesis. During mitosis, the spermatogonia or stem cells divide to produce two identical daughter cells, type A and B spermatogonia. Type-A...
10.9K
Sperm Structure and Semen Composition01:22

Sperm Structure and Semen Composition

14.1K
During ejaculation, males release around 2-5 milliliters of semen, which is a complex mixture of mature sperm and various fluids produced by accessory glands. The mature sperm cells measure approximately 60 micrometers in length and consist of a head, neck, midpiece, and tail. The head is flattened and tapered, measuring about 4 to 5 micrometers in length. It contains a nucleus with condensed chromosomes and an acrosome, a cap-like structure filled with enzymes essential for penetrating the...
14.1K
Sperm Transport01:15

Sperm Transport

4.8K
The journey of sperm from its origin to the point of ejaculation begins within the seminiferous tubules of the testis. Here, Sertoli cells produce fluid that propels non-motile sperm through a series of conduits, starting with the straight tubules leading to the rete testis. This interconnected network of tubules acts as the initial pathway for sperm, guiding them into the efferent ductules and then into the epididymis for maturation.
The maturation phase occurs in the epididymis, where sperm...
4.8K
The Y Chromosome Determines Maleness02:19

The Y Chromosome Determines Maleness

8.8K
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....
8.8K
Mate Choice01:20

Mate Choice

12.0K
Mate choice—the decision about whom to mate with—is a type of natural selection, since animals must reproduce to pass down their genes. Mate choice is also called intersexual selection because the behavior occurs between the sexes.
12.0K

You might also read

Related Articles

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

Sort by
Same author

Streaming for fish? Screen-based social exposure disrupts brain development.

Biology letters·2026
Same author

The evolution of eyespots in skates and rays.

Nature ecology & evolution·2026
Same author

Sperm performance of coastal northern pike (<i>Esox lucius L.</i>) from the Baltic Sea shows no impairment between freshwater and brackish conditions.

Conservation physiology·2026
Same author

Inbreeding strategies under social and sexual complexity: insights from female and male guppies.

Behavioral ecology : official journal of the International Society for Behavioral Ecology·2026
Same author

Male Strategic Association With Mating Partners Under Varying Social Contexts in a Livebearing Fish.

Ecology and evolution·2026
Same author

Cognitive advantages of large brains persist during an experimental heatwave.

Biology letters·2026

Related Experiment Video

Updated: Mar 30, 2026

Assessing Differences in Sperm Competitive Ability in Drosophila
09:34

Assessing Differences in Sperm Competitive Ability in Drosophila

Published on: August 22, 2013

15.2K

Sperm number trumps sperm size in mammalian ejaculate evolution.

Stefan Lüpold1, John L Fitzpatrick2

  • 1Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK stefan.luepold@ieu.uzh.ch.

Proceedings. Biological Sciences
|November 20, 2015
PubMed
Summary

Body size influences sperm evolution. Larger mammals evolve more, smaller sperm, supporting the sperm dilution hypothesis and explaining diverse sperm phenotypes.

Keywords:
body sizeejaculate investmentmeta-analysismetabolic constraint hypothesispostcopulatory sexual selectionsperm dilution hypothesis

More Related Videos

Sperm Collection of Differential Quality Using Density Gradient Centrifugation
03:28

Sperm Collection of Differential Quality Using Density Gradient Centrifugation

Published on: November 29, 2018

21.0K
Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract
10:07

Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract

Published on: June 6, 2019

13.1K

Related Experiment Videos

Last Updated: Mar 30, 2026

Assessing Differences in Sperm Competitive Ability in Drosophila
09:34

Assessing Differences in Sperm Competitive Ability in Drosophila

Published on: August 22, 2013

15.2K
Sperm Collection of Differential Quality Using Density Gradient Centrifugation
03:28

Sperm Collection of Differential Quality Using Density Gradient Centrifugation

Published on: November 29, 2018

21.0K
Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract
10:07

Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract

Published on: June 6, 2019

13.1K

Area of Science:

  • Evolutionary biology
  • Reproductive science
  • Sexual selection

Background:

  • Postcopulatory sexual selection drives sperm morphology diversity.
  • Contradictory hypotheses (sperm dilution vs. metabolic constraint) exist regarding sperm size evolution.
  • Mammalian body size and reproductive physiology offer a model to test these hypotheses.

Purpose of the Study:

  • To resolve the debate between the sperm dilution and metabolic constraint hypotheses.
  • To investigate the role of body size in mammalian sperm diversification.
  • To determine if body-size-mediated trade-offs explain sperm phenotype variation.

Main Methods:

  • Analysis of mammalian body size variation.
  • Examination of mammalian reproductive physiology.
  • Comparative evolutionary analysis of sperm traits (length and number).

Main Results:

  • Sperm evolved towards increased number and decreased length with increasing mammalian body size.
  • Findings support the sperm dilution hypothesis.
  • A trade-off between sperm size and number is mediated by body size.

Conclusions:

  • Body size is a key factor in mammalian sperm evolution.
  • The sperm dilution hypothesis explains the observed patterns of sperm diversification.
  • Body-size-mediated trade-offs between sperm size and number are crucial for understanding sperm phenotype diversity.