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Infertility in Males

Infertility in Males

Male infertility affects millions of couples worldwide, arising from various factors that impact different stages of the reproductive process. An endocrine imbalance resulting from conditions like hypogonadism, Klinefelter syndrome, or pituitary disorders can disrupt hormone levels and reduce sperm production. Testicular defects, such as tumors, cryptorchidism, atrophic testes, abnormal sperm morphology, and low sperm count or motility, may arise due to genetic factors, structural...

Infertility in Females

Infertility in Females

Female infertility is defined as the inability to conceive after a year of regular, unprotected intercourse and affects about 10–15% of couples worldwide. The primary cause of female infertility is ovulatory disorders, which hinder the release of eggs. These disorders can be classified as hypothalamic amenorrhea, polycystic ovarian syndrome (PCOS), premature ovarian failure, and hyperprolactinemic anovulation disorders.
Endometriosis, a condition characterized by abnormal growth of endometrial...

Menopause

Menopause

Menopause, a natural biological process marking the end of a woman's fertility, typically occurs between the fifth and sixth decade of life. This phase is characterized by the exhaustion of the ovarian follicle pool, leading to less responsive ovaries despite the high levels of Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). The consequential decrease in estrogen production results in symptoms like hot flashes, heavy sweating, headaches, hair loss, muscle pains, vaginal...

Conservation of Declining Populations

Conservation of Declining Populations

Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.

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...

Oogenesis

Oogenesis

In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from the equivalent procedure of spermatogenesis in males. First, meiotic divisions during oogenesis are asymmetric, meaning that a large oocyte (containing most of the cytoplasm) and minor polar body are produced as a result of meiosis I, and again following meiosis II. Since only oocytes will go on to form embryos if fertilized, this unequal...

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Related Experiment Video

Updated: Jun 5, 2026

Collection of Human Follicular Fluid, Follicle Somatic Cells, and Immature Oocytes from Individuals Undergoing In Vitro Fertilization

Collection of Human Follicular Fluid, Follicle Somatic Cells, and Immature Oocytes from Individuals Undergoing In Vitro Fertilization

Published on: October 24, 2025

Has fertility declined in recent decades?

Jørn Olsen¹, Jin Liang Zhu, Cecilia H Ramlau-Hansen

¹Department of Epidemiology, Institute of Public Health, University of Aarhus, Aarhus, Denmark.

Acta Obstetricia Et Gynecologica Scandinavica

|January 19, 2011

Summary

Human fertility and semen quality show no decline, based on recent Nordic data. Future monitoring is recommended to track biological fecundity trends and inform infertility research funding.

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Fertility Preservation Through Oocyte Vitrification: Clinical and Laboratory Perspectives

Fertility Preservation Through Oocyte Vitrification: Clinical and Laboratory Perspectives

Published on: September 16, 2021

Area of Science:

Reproductive biology
Human health
Epidemiology

Background:

Concerns exist regarding declining human fecundity, potentially linked to increased infertility treatments and demographic shifts.
Previous studies on semen quality decline over the past 50 years lack sufficient data for definitive conclusions.

Purpose of the Study:

To evaluate current trends in human semen quality and fecundity.
To address concerns about potential declines in fertility over time.

Main Methods:

Systematic review of 19 articles published within the last 5 years.
Analysis of data on semen quality and fecundity from Nordic countries since 2000.

Main Results:

Data from Nordic countries since 2000 do not indicate an ongoing decline in fertility.
Recent studies do not support a dramatic decline in semen quality or overall fecundity.

Conclusions:

While historical declines in semen quality and fecundity remain uncertain, future monitoring is feasible.
Research initiatives and official interest may increase funding for infertility research.