Complex sentence: The remainder of the phallic portion is for a time tubular, and then, by the absorption of the urogenital membrane, it establishes a communication with the exterior; this opening is the primitive urogenital ostium, and it extends forward to the corona glandis.
Split into simpler sentences: The remainder of the phallic portion is for a time tubular, and then, by the absorption of the urogenital membrane, it establishes a communication with the exterior. This opening is for a while the primitive urogenital opening, and it extends forward to the corona glandis.