Biology of Reproduction, Vol 17, 124-130, Copyright © 1977 by Society for the Study of Reproduction

Morphological and Biochemical Changes Which Occur During Postnatal Development and Maturation of the Rat Testis

¹ Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77025

Rat testicular development has been studied in an effort to characterize and correlate biochemical changes with the cell types present in the seminiferous epithelium. Between 4 and 60 days of age the body weight of the male albino rat increased from 10 to 265 gm, the testis weight increased from 8 to 1500 mg and the seminiferous tubule diameter increased from 50 µ to 230 µ. All three development curves of rat body weight, testis weight and seminiferous tubule diameter are sigmoidal in shape. Testicular dry weight decreases from 14.8% of the wet weight at 5 days of age to 12.8 percent at 60 days of age. The most rapid decline in the dry weight of the testis is closely associated with lumen formation in the seminiferous tubule. Total protein which represents 66% of the tissue dry weight declines from 102 to 82 mg/gm of tissue. Total RNA decreases from 11.5 to 8.0 mg/gm of tissue during testicular development. The DNA content of the testis shows the most impressive change with a value of 8.3 mg DNA/gm of tissue at 5 days of age declining to 1.8 mg of DNA/gm of tissue at 60 days of age. Many of the biochemical changes reported are correlated to the differentiating cell populations of the rat testis.

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ACKNOWLEDGMENTS We wish to acknowledge the assistance of Ms. Nancy Hammond in the preparation of this manuscript. This work was supported by research grant HD-07503 from the NIH and the Baylor Center for Population Research and Studies in Reproductive Biology (HD-07495). Anthony R. Means is the recipient of a Research Career Development Award from the NIH.