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Mitotic activity in monkey and rat Leydig cells
1Laboratoire d'Histologie, Université René Descartes, Paris, France.
Abstract:
The testes of the monkey, Macaca fascicularis, from birth to adulthood and of rats from puberty to adulthood were examined by both light and electron microscopy to estimate the mitotic activity of the Leydig cells. In monkeys, mitotic activity was measurable only in neonates: 2.3% in Leydig cells and 0.4% in fibroblast-like cells. From measurements of 3H-thymidine incorporation, mature Leydig cells were labeled in neonates (2%) and adult animals (1%). The labeling indices were significantly increased with increasing time after isotope exposure, and some pairs of labeled cells were found. In prepubertal (28 days of age) and pubertal (45 days of age) rats, mitotic indices were 2 and 0.2%, respectively, in the Leydig cells and 0.4 and 0.1% in fibroblast-like and myoid cells, respectively. Mitoses were not detected in postpubertal rats at 63 days of age. Taken together, these results demonstrate the self-renewal ability of mature Leydig cells during normal development.
Insights
Leydig cells in monkeys and rats show self-renewal during development. This study quantifies Leydig cell mitotic activity and 3H-thymidine incorporation in developing testes.
Area of Science:
- Reproductive Biology
- Cell Biology
- Developmental Biology
Background:
- Leydig cells are crucial for testosterone production in the testes.
- Understanding Leydig cell proliferation is key to reproductive health and development.
Purpose of the Study:
- To investigate the mitotic activity and self-renewal capacity of Leydig cells during normal development in non-human primates (Macaca fascicularis) and rodents (rats).
Main Methods:
- Light and electron microscopy were used to assess Leydig cell mitotic activity.
- 3H-thymidine incorporation was measured to evaluate DNA synthesis and cell proliferation.
- Studies were conducted on testes from neonatal to adult stages in monkeys and from prepubertal to adult stages in rats.
Main Results:
- In neonatal monkeys, Leydig cells exhibited a mitotic index of 2.3%, with 2% showing 3H-thymidine incorporation.
- In rats, mitotic indices decreased from 2% in prepubertal to 0.2% in pubertal Leydig cells.
- Labeled Leydig cells and pairs of labeled cells were observed, indicating cell division and self-renewal in both species.
Conclusions:
- Mature Leydig cells possess the ability to self-renew throughout normal development.
- Leydig cell proliferation is most active during early developmental stages and declines with maturity.
- These findings contribute to understanding testicular function and potential therapeutic targets for reproductive disorders.