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Sperm Transport

Sperm Transport

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...

Sperm Structure and Semen Composition

Sperm Structure and Semen Composition

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...

Male Sexual Response: Erection & Ejaculation

Male Sexual Response: Erection & Ejaculation

Sexual stimulation can take various forms, such as physical touch and visual or auditory cues. When this happens, the parasympathetic reflex in the sacral portion of the spinal cord is activated. This reflex stimulates the release of nitric oxide (NO), which then dilates the arterioles in the penis, increasing blood flow to the erectile tissues - the corpora cavernosa and corpus spongiosum.
The blood filling the erectile tissues compresses the veins, which helps to prevent blood from leaving...

Accessory Glands of the Male Reproductive System

Accessory Glands of the Male Reproductive System

The accessory ducts involved in sperm maturation and transportation include the epididymides, vasa deferentia, ejaculatory ducts, and urethra. These ducts play a critical role in the maturation, storage, 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. The epididymis can be divided into three main parts: the head, body, and tail. The head of the epididymis...

Accessory Ducts of the Male Reproductive System

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.

Spermatogenesis

Spermatogenesis

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 reproductive...

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Related Experiment Video

Updated: Jul 8, 2026

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa

Published on: December 30, 2014

One-sided ejaculation of echidna sperm bundles.

S D Johnston¹, B Smith, M Pyne

¹School of Animal Studies, University of Queensland, Gatton, Queensland 4343, Australia. s.johnston1@uq.edu.au

The American Naturalist

|January 4, 2008

Summary

The short-beaked echidna uses a unique, alternating ejaculatory mechanism, unlike any other mammal. Researchers also observed motile sperm bundles in echidna semen, suggesting potential sperm competition.

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Last Updated: Jul 8, 2026

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa

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Published on: December 30, 2014

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Analysis of Epididymal Protein Synthesis and Secretion

Analysis of Epididymal Protein Synthesis and Secretion

Published on: August 25, 2018

Area of Science:

Reproductive biology
Comparative anatomy
Monotreme research

Background:

Monotremes, such as the short-beaked echidna, represent a unique lineage of mammals with distinct reproductive strategies.
Understanding monotreme reproductive mechanisms provides insights into mammalian evolution.

Purpose of the Study:

To document the novel ejaculatory mechanism in the short-beaked echidna.
To investigate the morphology and motility of sperm in echidna semen.
To explore the evolutionary implications of these findings.

Main Methods:

Observation of reproductive behavior in short-beaked echidnas.
Scanning electron microscopy of ejaculated semen.
Comparative analysis with reptilian reproductive systems.

Main Results:

An unusual alternate use of each side of the bilaterally symmetrical glans penis during ejaculation was observed.
Motile sperm bundles were identified in the ejaculated semen.
The observed mechanism is reminiscent of hemipenes in squamate reptiles.

Conclusions:

The echidna's ejaculatory mechanism is unparalleled in mammals and suggests a potential sauropsidian lineage connection.
Sperm bundling may enhance sperm motility, potentially enabling sperm competition in echidnas.