# CONTROL OF SERTOLI CELL NUMBER AND TESTICULAR SIZE

> **NIH NIH R01** · TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR · 1992 · $113,174

## Abstract

The objective is to understand how spermatogenesis and the rate of sperm
production are regulated or modulated.  Degeneration of germ cells is a
common phenomenon of spermatogenesis which reduces theoretical values of
daily sperm production in both animals and men.  As high as 75% loss of
theoretical values occurs during spermatocytogenesis.  However, little is
known about its mechanism, causes, relationship to somatic cell
populations, or its prevention.  To evaluate the roles of degeneration and
number of stem cells on daily sperm production, both quantitative and
autoradiographic studies will be conducted using light microscopy.  We have
shown that changes in numbers of A spermatagonia are largely responsible
for seasonal variation in daily sperm production in stallions.  This study
will determine if increased number of A spermatogonia can be explained by
increased number of stem cells or by less degeneration among subtypes of
spermatogonia.  Evaluation of stem cell number and degeneration of
spermatogonia in different seasons, in which differences in daily sperm
production are known to occur naturally, will reveal which aspects in
spermatocytogenesis are flexible and possible amenable to intervention.
The long-term labelling experiment should aid in evaluating the "reserve"
stem cell concept as these cells should not be labelled if they are dormant
in testes with active spermatogenesis.  Interrelationships between
spermatogonia and the Sertoli cell or Leydig cell population will be
evaluated.  Through autoradiographic and quantitative studies, the role of
mitosis on number of Sertoli cells and Leydig cells will be evaluated.  The
temporal relationships between daily sperm production, stem cell number,
germ cell degeneration, size of populations of Sertoli cells and Leydig
cells, and hormone concentrations will be evaluated.  Electron microscopy
will be used to support light microscopy.  The seasonally regressed
stallion testis appears to be useful in evaluating the interrelationships
of changes in the aging human testis.  Both exhibit reduced sperm
production rate, reduced numbers of spermatogonia, and reduced numbers of
Sertoli cells and Leydig cells.  The gametic function of the aging human
testis is becoming more important as more people live longer.  Knowledge of
how sperm production rate may be regulated also is useful to human family
planning programs involving oligospermic men and contraception strategies.

## Key facts

- **NIH application ID:** 3123083
- **Project number:** 9R01AG011093-08
- **Recipient organization:** TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
- **SAM.gov UEI:** HFT7XTHB6563
- **Principal Investigator:** LARRY JOHNSON
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $113,174
- **Award type:** 9
- **Project period:** 1992-06-01 → 1995-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3123083

## Citation

> US National Institutes of Health, RePORTER application 3123083, CONTROL OF SERTOLI CELL NUMBER AND TESTICULAR SIZE (9R01AG011093-08). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3123083. Licensed CC0.

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