Fine structure of spermatogonia and intercellular bridges in Macaca nemestrina

Spermatogonia of the monkey, Macaca nemestrina , were studied with the electron microscope. The spermatogonial nucleus is characterized by dense homogeneous chromatin and an eccentric nucleolus with a prominent surrounding clear zone. Cytoplasm consists chiefly of free ribosomes and vesicular endoplasmic reticulum. Scattered mitochondria with closely spaced transverse cristae are arranged singly and in pairs separated by thin electron‐dense bands. Binucleated spermatogonia resemble other spermatogonia in their ultrastructural characteristics, but contain an increased number of lysosome‐like structures and degenerating mitochondria. Spermatogonial interconnections are of two types: broad cytoplasmic connections and narrow intercellular bridges. Connected cells are always identical in appearance and stage of maturation. Multiple connections occur. Interconnection of spermatogonia provides a syncytial type of arrangement which allows synchronization of differentiation and results in similar apperance of adjoining cells. Similarity of regressive changes in adjacent degenerating cells is explained by the presence of intercellular bridges.