The sperm character working out. Extreme close-ups of him performing chin-ups, sit ups and skipping. This retains some ambiguity about the character's form. 
After titles, sperm is resting. Shift focus from his face to the wall lamp which flashes (with sound of siren) which awakens him. Sperm investigates commotion outside room, and witnesses mass sperm stampede.
Sperm exits to follow crowd. Race sequence ensues. Upon discovering egg he swims towards it, disappears over hill and reappears in the distance, swimming towards the egg. Close-up as he enters.
When nothing happens Sperm is bemused at anti-climax, and so moves egg towards small opening (as seen from main room). He forces egg-bubble through opening (as seen from inside next room) where he bursts from the false egg onto the floor.
He is mocked by peers shown in silhouette and shot from a low angle. Ashamed and humiliated he returns to his training with a more enthusiastic regime.
Lifting weights (a red blood cell - pumping iron...eh? No.) in XCU again. He begins to float inexplicably, seen from below. Dropping the bloodcell he swims to the opening.
Repeat shot of stampede, again he follows not knowing the reason. Determined to be the fastest he propels himself with a spinning motion, arcing up and down in shot as background rushes by. Leading the race he spies an opponent gaining on him.
He sets up a dastardly trap using an ingrowing hair as a garotting-type wire which promptly "clotheslines" his unsuspecting opponent, who becomes entangled in the pube (That is not at all good is it...). Sperm meanwhile reaches his goal and becomes transfixed, entering a dream sequence (not shown). 
Shown from behind Sperm, he moves forwards towards the growing light source. Camera stops and he swims into the light as a shrinking silhouette against an ultimately all-white background.As I'm sure you already know, it turns out his first and last adventure was all in the name of a cheeky wank. Bird's eye shot of a young man's bedroom pans out from the fullscreen white of a tissue in the bin. Right.
