# Quantitative Postnatal Maturation of the Feline Testis from 6 to 36 Months: A Stereological and DHH Immunomorphological Analysis

## TL;DR

This study provides detailed insights into how the testes of domestic cats mature from 6 to 36 months, offering valuable data for veterinary and conservation efforts.

## Contribution

The study quantifies postnatal testicular maturation in cats using stereology and DHH immunomorphology, revealing age-related structural changes.

## Key findings

- Testicular volume and volumes of seminiferous epithelium, Sertoli cells, and Leydig cells increase significantly with age.
- Desert Hedgehog immunoreactivity declines as testes mature, indicating interstitial cell development.
- Principal component analysis distinguishes immature and mature testes based on structural variables.

## Abstract

Understanding how the testis grows and matures in domestic cats is important for veterinarians, breeders, and conservation programs for wild feline species. Although the development of the male reproductive system in cats has been described in general terms, detailed information about how the internal structures of the testis change with age has been lacking. In this study, we examined testicular tissue from healthy cats between six and thirty-six months old that had been neutered for routine clinical or population-control reasons. By using high-resolution imaging and precise measurements at the microscopic level, we were able to quantify how the cells and tissues inside the testis expand and reorganize as cats grow from early puberty into adulthood. We also measured the presence of a signal produced by supporting cells in the testis, known to guide development, and found that it decreased as the testis reached maturity. Our findings provide a clear picture of the normal postnatal development of the feline testis and offer valuable reference information for clinical assessment, reproductive management, and conservation efforts involving domestic and wild cats.

Postnatal testicular maturation in domestic cats remains poorly quantified despite its relevance for reproductive biology, veterinary practice, and the management of threatened felid species. This study aimed to characterize age-related changes in testicular structure from six to thirty-six months of age. Testes were collected from clinically healthy cats undergoing routine orchiectomy, and design-based stereology was used to estimate the volumes and densities of the main testicular components, including the seminiferous epithelium, interstitial tissue, Sertoli cells, and Leydig cells. Immunohistochemical detection of Desert Hedgehog, a developmental signaling molecule, was performed to assess interstitial maturation. Testicular volume and the absolute volumes of the seminiferous epithelium, Sertoli cells, and Leydig cells increased significantly with age, while the numerical density of Leydig cells remained stable, indicating hypertrophy rather than proliferation. Desert Hedgehog immunoreactivity declined progressively across age groups, consistent with the transition from immature to mature interstitial cells. Principal component analysis revealed a clear separation between immature and mature testes based on volumetric and density variables. These results demonstrate that feline testicular maturation follows a coordinated pattern of tubular and interstitial growth and provide quantitative reference values useful for reproductive assessment, comparative studies, and conservation programs in domestic and wild felids.