Several components of the female reproductive system of Pharyngostomoides procyonis, including the vitellaria and vitelline duct, ovary and oviduct, Laurer's canal, and Mehlis' gland and associated ducts, were observed with the electron microscope. Vitelline follicles contain cells in various stages of development. Mature vitelline cells contain membrane-delimited clusters of vitelline globules near the plasma membrane. Cilia are present in the vitelline duct. The ovary contains germ cells in various stages of maturation. Oogonia are found in the peripheral region. Mature oocytes contain numerous dense bodies near the plasmalemma. Also included in the cytoplasm of mature oocytes are "nucleolus-like bodies," myelin-like bodies, and mitochondria containing dense granules and few cristae. The epithelium of the oviduct is ciliated. Sperm are present in the oviduct and in Laurer's canal. Two types of secretory cells found in Mehlis' gland are described.

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Spermatogonia, nutritive cells, and developmental stages of spermatids were observed with the electron microscope. Spermatogonia are near the surface of the testis and contain large nuclei and comparatively little cytoplasm. Nutritive or supporting cells are associated with the spermatogonia. Early spermatids are characterized by a circle of mitochondria around the nucleus. Late spermatids have 2 parallel free flagella separated by a cytoplasmic process, and a nucleus containing electron-dense strands of chromatin arranged in coils or concentric layers. Mature sperm have 2 flagella enclosed by cytoplasm. Their nuclei contain dense, fibrillar chromatin. A microtubule-organizing center (MTOC) found between basal bodies of spermatids is described. Descriptions are presented of the seminal reservoir, seminal vesicle, and the sperm found in those organs.