ASTRID & HANNS-FRIEDER MICHLER / SCIENCE PHOTO LIBRARY ASTRID & HANNS-FRIEDER MICHLER / SCIENCE PHOTO LIBRARY
Light micrograph of normal human testis. Sperm is produced in a system of coiled seminiferous tubules, seen here in cross section. The background comprises interstitial cells, and shows three blood vessels (one left, two right, red). Each sectioned tubule is bounded by a basement membrane. The immature spermatogonia cells, next to this, develop first into spermatocytes, then spermatids, as they migrate towards the centre of the tubule. Also at the basement membrane level are Sertoli cells, of which the most obvious is close to the blood vessel, left (large round purple nucleus). Magnification x50 at 35mm size.
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